Merge branch '2.0' of https://github.com/taosdata/TDengine into 2.0

src/inc/trpc.h

@@ -33,83 +33,42 @@ extern "C" {
 #define TAOS_SOCKET_TYPE_NAME_TCP  "tcp"
 #define TAOS_SOCKET_TYPE_NAME_UDP  "udp"
 
-#define TAOS_ID_ASSIGNED   0
-#define TAOS_ID_FREE       1
-#define TAOS_ID_REALLOCATE 2
-
 #define TAOS_CONN_SOCKET_TYPE_S()  ((strcasecmp(tsSocketType, TAOS_SOCKET_TYPE_NAME_UDP) == 0)? TAOS_CONN_UDPS:TAOS_CONN_TCPS)
 #define TAOS_CONN_SOCKET_TYPE_C()  ((strcasecmp(tsSocketType, TAOS_SOCKET_TYPE_NAME_UDP) == 0)? TAOS_CONN_UDPC:TAOS_CONN_TCPC)
 
-#define taosSendMsgToPeer(x, y, z) taosSendMsgToPeerH(x, y, z, NULL)
-#define taosOpenRpcChann(x, y, z) taosOpenRpcChannWithQ(x,y,z,NULL)
-#define taosBuildReqMsg(x, y) taosBuildReqMsgWithSize(x, y, 512)
-#define taosBuildRspMsg(x, y) taosBuildRspMsgWithSize(x, y, 512)
+extern int tsRpcHeadSize;
 
 typedef struct {
   char *localIp;                        // local IP used
   uint16_t localPort;                   // local port
   char *label;                          // for debug purpose
   int   numOfThreads;                   // number of threads to handle connections
-  void *(*fp)(char *, void *, void *);  // function to process the incoming msg
-  void *qhandle;                        // queue handle
-  int   bits;                           // number of bits for sessionId
-  int   numOfChanns;                    // number of channels
-  int   sessionsPerChann;               // number of sessions per channel
-  int   idMgmt;                         // TAOS_ID_ASSIGNED, TAOS_ID_FREE
+  void *(*fp)(char type, char *pCont, int contLen, void *handle, int index);  // function to process the incoming msg
+  int   sessions;                       // number of sessions allowed
   int   connType;                       // TAOS_CONN_UDP, TAOS_CONN_TCPC, TAOS_CONN_TCPS
   int   idleTime;                       // milliseconds, 0 means idle timer is disabled
-  int   noFree;                         // not free buffer
-  void (*efp)(int cid);                 // call back function to process not activated chann
-  int (*afp)(char *meterId, char *spi, char *encrypt, uint8_t *secret,
-             uint8_t *ckey);  // call back to retrieve auth info
-} SRpcInit;
-
-typedef struct {
-  int      cid;       // channel ID
-  int      sid;       // session ID
-  char *   meterId;   // meter ID
-  uint32_t peerId;    // peer link ID
-  void *   shandle;   // pointer returned by taosOpenRpc
-  void *   ahandle;   // handle provided by app
-  char *   peerIp;    // peer IP string
-  uint16_t    peerPort;  // peer port
+  char *meterId;   // meter ID
   char  spi;       // security parameter index
   char  encrypt;   // encrypt algorithm
-  char *   secret;    // key for authentication
-  char *   ckey;      // ciphering key
-} SRpcConnInit;
-
-extern int tsRpcHeadSize;
-
-void *taosOpenRpc(SRpcInit *pRpc);
-
-void taosCloseRpc(void *);
-
-int taosOpenRpcChannWithQ(void *handle, int cid, int sessions, void *qhandle);
-
-void taosCloseRpcChann(void *handle, int cid);
-
-void *taosOpenRpcConn(SRpcConnInit *pInit, uint8_t *code);
-
-void taosCloseRpcConn(void *thandle);
-
-void taosStopRpcConn(void *thandle);
-
-int taosSendMsgToPeerH(void *thandle, char *pCont, int contLen, void *ahandle);
-
-char *taosBuildReqHeader(void *param, char type, char *msg);
-
-char *taosBuildReqMsgWithSize(void *, char type, int size);
-
-char *taosBuildRspMsgWithSize(void *, char type, int size);
-
-int taosSendSimpleRsp(void *thandle, char rsptype, char code);
-
-int taosSetSecurityInfo(int cid, int sid, char *id, int spi, int encrypt, char *secret, char *ckey);
+  char *secret;    // key for authentication
+  char *ckey;      // ciphering key
+  int   (*afp) (char *meterId, char *spi, char *encrypt, uint8_t *secret, uint8_t *ckey); // call back to retrieve auth info
+} SRpcInit;
 
-void taosGetRpcConnInfo(void *thandle, uint32_t *peerId, uint32_t *peerIp, uint16_t *peerPort, int *cid, int *sid);
+typedef struct {
+  int16_t   index; 
+  int16_t   numOfIps;
+  uint32_t  ip[TSDB_MAX_REPLICA];
+} SRpcIpSet;
+
+void *rpcOpen(SRpcInit *pRpc);
+void  rpcClose(void *);
+char *rpcMallocCont(int contLen);
+void  rpcFreeCont(char *pCont);
+void  rpcSendRequest(void *thandle, SRpcIpSet ipSet, char msgType, void *pCont, int contLen, void *ahandle);
+void  rpcSendResponse(void *pConn, void *pCont, int contLen);
+void  rpcSendSimpleRsp(void *pConn, int32_t code);
 
-int taosGetOutType(void *thandle);
 
 #ifdef __cplusplus
 }

src/rpc/inc/tcache.h

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TDENGINE_TSCCACHE_H
+#define TDENGINE_TSCCACHE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *taosOpenConnCache(int maxSessions, void (*cleanFp)(void *), void *tmrCtrl, int64_t keepTimer);
+
+void taosCloseConnCache(void *handle);
+
+void *taosAddConnIntoCache(void *handle, void *data, uint32_t ip, uint16_t port, char *user);
+
+void *taosGetConnFromCache(void *handle, uint32_t ip, uint16_t port, char *user);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // TDENGINE_TSCACHE_H

src/rpc/src/tcache.c

+/*
+ * Copyright (c) 2019 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "os.h"
+
+#include "tglobalcfg.h"
+#include "tlog.h"
+#include "tmempool.h"
+#include "tsclient.h"
+#include "ttime.h"
+#include "ttimer.h"
+#include "tutil.h"
+
+typedef struct _c_hash_t {
+  uint32_t          ip;
+  uint16_t          port;
+  struct _c_hash_t *prev;
+  struct _c_hash_t *next;
+  void *            data;
+  uint64_t          time;
+} SConnHash;
+
+typedef struct {
+  SConnHash **    connHashList;
+  mpool_h         connHashMemPool;
+  int             maxSessions;
+  int             total;
+  int *           count;
+  int64_t         keepTimer;
+  pthread_mutex_t mutex;
+  void (*cleanFp)(void *);
+  void *tmrCtrl;
+  void *pTimer;
+} SConnCache;
+
+int taosHashConn(void *handle, uint32_t ip, uint16_t port, char *user) {
+  SConnCache *pObj = (SConnCache *)handle;
+  int         hash = 0;
+  // size_t    user_len = strlen(user);
+
+  hash = ip >> 16;
+  hash += (unsigned short)(ip & 0xFFFF);
+  hash += port;
+  while (*user != '\0') {
+    hash += *user;
+    user++;
+  }
+
+  hash = hash % pObj->maxSessions;
+
+  return hash;
+}
+
+void taosRemoveExpiredNodes(SConnCache *pObj, SConnHash *pNode, int hash, uint64_t time) {
+  if (pNode == NULL) return;
+  if (time < pObj->keepTimer + pNode->time) return;
+
+  SConnHash *pPrev = pNode->prev, *pNext;
+
+  while (pNode) {
+    (*pObj->cleanFp)(pNode->data);
+    pNext = pNode->next;
+    pObj->total--;
+    pObj->count[hash]--;
+    tscTrace("%p ip:0x%x:%hu:%d:%p removed, connections in cache:%d", pNode->data, pNode->ip, pNode->port, hash, pNode,
+             pObj->count[hash]);
+    taosMemPoolFree(pObj->connHashMemPool, (char *)pNode);
+    pNode = pNext;
+  }
+
+  if (pPrev)
+    pPrev->next = NULL;
+  else
+    pObj->connHashList[hash] = NULL;
+}
+
+void *taosAddConnIntoCache(void *handle, void *data, uint32_t ip, uint16_t port, char *user) {
+  int         hash;
+  SConnHash * pNode;
+  SConnCache *pObj;
+
+  uint64_t time = taosGetTimestampMs();
+
+  pObj = (SConnCache *)handle;
+  if (pObj == NULL || pObj->maxSessions == 0) return NULL;
+
+  if (data == NULL) {
+    tscTrace("data:%p ip:%p:%d not valid, not added in cache", data, ip, port);
+    return NULL;
+  }
+
+  hash = taosHashConn(pObj, ip, port, user);
+  pNode = (SConnHash *)taosMemPoolMalloc(pObj->connHashMemPool);
+  pNode->ip = ip;
+  pNode->port = port;
+  pNode->data = data;
+  pNode->prev = NULL;
+  pNode->time = time;
+
+  pthread_mutex_lock(&pObj->mutex);
+
+  pNode->next = pObj->connHashList[hash];
+  if (pObj->connHashList[hash] != NULL) (pObj->connHashList[hash])->prev = pNode;
+  pObj->connHashList[hash] = pNode;
+
+  pObj->total++;
+  pObj->count[hash]++;
+  taosRemoveExpiredNodes(pObj, pNode->next, hash, time);
+
+  pthread_mutex_unlock(&pObj->mutex);
+
+  tscTrace("%p ip:0x%x:%hu:%d:%p added, connections in cache:%d", data, ip, port, hash, pNode, pObj->count[hash]);
+
+  return pObj;
+}
+
+void taosCleanConnCache(void *handle, void *tmrId) {
+  int         hash;
+  SConnHash * pNode;
+  SConnCache *pObj;
+
+  pObj = (SConnCache *)handle;
+  if (pObj == NULL || pObj->maxSessions == 0) return;
+  if (pObj->pTimer != tmrId) return;
+
+  uint64_t time = taosGetTimestampMs();
+
+  for (hash = 0; hash < pObj->maxSessions; ++hash) {
+    pthread_mutex_lock(&pObj->mutex);
+    pNode = pObj->connHashList[hash];
+    taosRemoveExpiredNodes(pObj, pNode, hash, time);
+    pthread_mutex_unlock(&pObj->mutex);
+  }
+
+  // tscTrace("timer, total connections in cache:%d", pObj->total);
+  taosTmrReset(taosCleanConnCache, pObj->keepTimer * 2, pObj, pObj->tmrCtrl, &pObj->pTimer);
+}
+
+void *taosGetConnFromCache(void *handle, uint32_t ip, uint16_t port, char *user) {
+  int         hash;
+  SConnHash * pNode;
+  SConnCache *pObj;
+  void *      pData = NULL;
+
+  pObj = (SConnCache *)handle;
+  if (pObj == NULL || pObj->maxSessions == 0) return NULL;
+
+  uint64_t time = taosGetTimestampMs();
+
+  hash = taosHashConn(pObj, ip, port, user);
+  pthread_mutex_lock(&pObj->mutex);
+
+  pNode = pObj->connHashList[hash];
+  while (pNode) {
+    if (time >= pObj->keepTimer + pNode->time) {
+      taosRemoveExpiredNodes(pObj, pNode, hash, time);
+      pNode = NULL;
+      break;
+    }
+
+    if (pNode->ip == ip && pNode->port == port) break;
+
+    pNode = pNode->next;
+  }
+
+  if (pNode) {
+    taosRemoveExpiredNodes(pObj, pNode->next, hash, time);
+
+    if (pNode->prev) {
+      pNode->prev->next = pNode->next;
+    } else {
+      pObj->connHashList[hash] = pNode->next;
+    }
+
+    if (pNode->next) {
+      pNode->next->prev = pNode->prev;
+    }
+
+    pData = pNode->data;
+    taosMemPoolFree(pObj->connHashMemPool, (char *)pNode);
+    pObj->total--;
+    pObj->count[hash]--;
+  }
+
+  pthread_mutex_unlock(&pObj->mutex);
+
+  if (pData) {
+    tscTrace("%p ip:0x%x:%hu:%d:%p retrieved, connections in cache:%d", pData, ip, port, hash, pNode, pObj->count[hash]);
+  }
+
+  return pData;
+}
+
+void *taosOpenConnCache(int maxSessions, void (*cleanFp)(void *), void *tmrCtrl, int64_t keepTimer) {
+  SConnHash **connHashList;
+  mpool_h     connHashMemPool;
+  SConnCache *pObj;
+
+  connHashMemPool = taosMemPoolInit(maxSessions, sizeof(SConnHash));
+  if (connHashMemPool == 0) return NULL;
+
+  connHashList = calloc(sizeof(SConnHash *), maxSessions);
+  if (connHashList == 0) {
+    taosMemPoolCleanUp(connHashMemPool);
+    return NULL;
+  }
+
+  pObj = malloc(sizeof(SConnCache));
+  if (pObj == NULL) {
+    taosMemPoolCleanUp(connHashMemPool);
+    free(connHashList);
+    return NULL;
+  }
+  memset(pObj, 0, sizeof(SConnCache));
+
+  pObj->count = calloc(sizeof(int), maxSessions);
+  pObj->total = 0;
+  pObj->keepTimer = keepTimer;
+  pObj->maxSessions = maxSessions;
+  pObj->connHashMemPool = connHashMemPool;
+  pObj->connHashList = connHashList;
+  pObj->cleanFp = cleanFp;
+  pObj->tmrCtrl = tmrCtrl;
+  taosTmrReset(taosCleanConnCache, pObj->keepTimer * 2, pObj, pObj->tmrCtrl, &pObj->pTimer);
+
+  pthread_mutex_init(&pObj->mutex, NULL);
+
+  return pObj;
+}
+
+void taosCloseConnCache(void *handle) {
+  SConnCache *pObj;
+
+  pObj = (SConnCache *)handle;
+  if (pObj == NULL || pObj->maxSessions == 0) return;
+
+  pthread_mutex_lock(&pObj->mutex);
+
+  taosTmrStopA(&(pObj->pTimer));
+
+  if (pObj->connHashMemPool) taosMemPoolCleanUp(pObj->connHashMemPool);
+
+  tfree(pObj->connHashList);
+  tfree(pObj->count)
+
+      pthread_mutex_unlock(&pObj->mutex);
+
+  pthread_mutex_destroy(&pObj->mutex);
+
+  memset(pObj, 0, sizeof(SConnCache));
+  free(pObj);
+}

src/rpc/src/trpc.c

@@ -21,7 +21,7 @@
 #include "tmd5.h"
 #include "tmempool.h"
 #include "trpc.h"
-#include "taosdef.h"
+#include "tsdb.h"
 #include "tsocket.h"
 #include "ttcpclient.h"
 #include "ttcpserver.h"
@@ -31,15 +31,40 @@
 #include "tutil.h"
 #include "lz4.h"
 
-typedef struct _msg_node {
-  struct _msg_node *next;
-  void *            ahandle;
-  int               msgLen;
-} SMsgNode;
+#define RPC_MSG_OVERHEAD (sizeof(SRpcReqContext) + sizeof(SRpcHeader) + sizeof(SRpcDigest)) 
+#define rpcHeaderFromCont(cont) ((STaosHeader *) (cont - sizeof(SRpcHeader)))
+#define rpcContFromHeader(msg) ( msg + sizeof(SRpcHeader))
+#define rpcMsgLenFromCont(contLen) ( contLen + sizeof(SRpcHeader))
+#define rpcContLenFromMsg(msgLen) (msgLen - sizeof(SRpcHeader))
+#define rpcIsReq(type) (type & 1U)
+
+typedef struct {
+  int      sessions;
+  int      numOfThreads;
+  int      type;
+  int      idleTime; // milliseconds;
+  uint16_t localPort;
+  char     label[12];
+
+  char    *meterId;   // meter ID
+  char     spi;       // security parameter index
+  char     encrypt;   // encrypt algorithm
+  char    *secret;    // key for authentication
+  char    *ckey;      // ciphering key
+
+  void *(*fp)(char *, void *ahandle, void *thandle);  // FP to call the application
+  int   (*afp)(char *meterId, char *spi, char *encrypt, uint8_t *secret, uint8_t *ckey); // FP to retrieve auth info
+  SRpcConn *connList;
+  void     *idPool;
+  void     *tmrCtrl;
+  void     *hash;
+  void     *shandle;  // returned handle from lower layer during initialization
+  void     *pCache;   // connection cache
+  pthread_mutex_t mutex;
+} SRpcInfo;
 
 typedef struct {
-  void *   signature;
-  int      chann;   // channel ID
+  void     *signature;
   int       sid;     // session ID
   uint32_t  ownId;   // own link ID
   uint32_t  peerId;  // peer link ID
@@ -58,51 +83,54 @@ typedef struct {
   uint16_t  inTranId;
   uint8_t   outType;
   char      inType;
-  char               closing;
-  char               rspReceived;
-  void *             chandle;  // handle passed by TCP/UDP connection layer
-  void *             ahandle;  // handle returned by upper app layter
+  void     *chandle;  // handle passed by TCP/UDP connection layer
+  void     *ahandle;  // handle provided by upper app layter
   int       retry;
   int       tretry;   // total retry
-  void *             pTimer;
-  void *             pIdleTimer;
-  char *             pRspMsg;
-  char *             pQuickRsp;
+  void     *pTimer;
+  void     *pIdleTimer;
+  char     *pRspMsg;  // including header
   int       rspMsgLen;
-  SMsgNode *         pMsgNode;
-  SMsgNode *         pHead, *pTail;
-  struct rpc_server *pServer;
+  char     *pReqMsg;  // including header
+  int       reqMsgLen;
+  SRpcInfo *pRpc;
 } SRpcConn;
 
 typedef struct {
-  int             sessions;
-  void *          qhandle; // for scheduler
-  SRpcConn *      connList;
-  void *          idPool;
-  void *          tmrCtrl;
-  void *          hash;
-  pthread_mutex_t mutex;
-} SRpcChann;
+  SRpcIpSet ipSet;
+  void     *ahandle;
+  SRpcInfo *pRpc;
+  char      type;
+  char     *pCont;
+  int       contLen;
+  int       numOfRetry;
+  char      msg[];
+} SRpcReqContext;
 
-typedef struct rpc_server {
-  void *shandle;  // returned handle from lower layer during initialization
-  void *qhandle;  // for scheduler
-  int   bits;     // number of bits for session ID
-  int   mask;
-  int   numOfChanns;
-  int   numOfThreads;
-  int   idMgmt;   // ID management method
-  int   type;
-  int   idleTime; // milliseconds;
-  int   noFree;   // do not free the request msg when rsp is received
-  int   index;    // for UDP server, next thread for new connection
-  uint16_t localPort;
-  char  label[12];
-  void *(*fp)(char *, void *ahandle, void *thandle);
-  void (*efp)(int);                                                                     // FP to report error
-  int (*afp)(char *meterId, char *spi, char *encrypt, uint8_t *secret, uint8_t *ckey);  // FP to retrieve auth info
-  SRpcChann *channList;
-} STaosRpc;
+typedef struct {
+  char     version : 4;
+  char     comp : 4;
+  char     tcp : 2;
+  char     spi : 3;
+  char     encrypt : 3;
+  uint16_t tranId;
+  uint32_t uid;  // for unique ID inside a client
+  uint32_t sourceId;
+
+  uint32_t destId;
+  uint32_t destIp;
+  char     meterId[TSDB_UNI_LEN];
+  uint16_t port;  // for UDP only
+  char     empty[1];
+  uint8_t  msgType;
+  int32_t  msgLen;
+  uint8_t  content[0];
+} SRpcHeader;
+
+typedef struct {
+  uint32_t timeStamp;
+  uint8_t  auth[TSDB_AUTH_LEN];
+} SRpcDigest;
 
 int tsRpcProgressTime = 10;  // milliseocnds
 
@@ -111,13 +139,25 @@ int tsRpcMaxRetry;
 int tsRpcHeadSize;
 
 void *(*taosInitConn[])(char *ip, uint16_t port, char *label, int threads, void *fp, void *shandle) = {
-    taosInitUdpServer, taosInitUdpClient, taosInitTcpServer, taosInitTcpClient};
+    taosInitUdpServer, 
+    taosInitUdpClient, 
+    taosInitTcpServer, 
+    taosInitTcpClient
+};
 
-void (*taosCleanUpConn[])(void *thandle) = {taosCleanUpUdpConnection, taosCleanUpUdpConnection, taosCleanUpTcpServer,
-                                            taosCleanUpTcpClient};
+void (*taosCleanUpConn[])(void *thandle) = {
+    taosCleanUpUdpConnection, 
+    taosCleanUpUdpConnection, 
+    taosCleanUpTcpServer,
+    taosCleanUpTcpClient
+};
 
 int (*taosSendData[])(uint32_t ip, uint16_t port, char *data, int len, void *chandle) = {
-    taosSendUdpData, taosSendUdpData, taosSendTcpServerData, taosSendTcpClientData};
+    taosSendUdpData, 
+    taosSendUdpData, 
+    taosSendTcpServerData, 
+    taosSendTcpClientData
+};
 
 void *(*taosOpenConn[])(void *shandle, void *thandle, char *ip, uint16_t port) = {
     taosOpenUdpConnection,
@@ -126,19 +166,22 @@ void *(*taosOpenConn[])(void *shandle, void *thandle, char *ip, uint16_t port) =
     taosOpenTcpClientConnection,
 };
 
-void (*taosCloseConn[])(void *chandle) = {NULL, NULL, taosCloseTcpServerConnection, taosCloseTcpClientConnection};
+void (*taosCloseConn[])(void *chandle) = {
+    NULL, 
+    NULL, 
+    taosCloseTcpServerConnection, 
+    taosCloseTcpClientConnection
+};
 
-int   taosReSendRspToPeer(SRpcConn *pConn);
-void  taosProcessTaosTimer(void *, void *);
-void *taosProcessDataFromPeer(char *data, int dataLen, uint32_t ip, uint16_t port, void *shandle, void *thandle,
-                              void *chandle);
-int   taosSendDataToPeer(SRpcConn *pConn, char *data, int dataLen);
-void  taosProcessSchedMsg(SSchedMsg *pMsg);
-int   taosAuthenticateMsg(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey);
-int   taosBuildAuthHeader(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey);
+int   rpcResendRspToPeer(SRpcConn *pConn);
+void  rpcProcessRetryTimer(void *, void *);
+void *rpcProcessDataFromPeer(char *data, int dataLen, uint32_t ip, uint16_t port, void *shandle, void *thandle, void *chandle);
+int   rpcSendDataToPeer(SRpcConn *pConn, char *data, int dataLen);
+int   rpcAuthenticateMsg(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey);
+int   rpcBuildAuthHeader(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey);
 
-static int32_t taosCompressRpcMsg(char* pCont, int32_t contLen) {
-  STaosHeader* pHeader = (STaosHeader *)(pCont - sizeof(STaosHeader));
+static int32_t rpcCompressRpcMsg(char* pCont, int32_t contLen) {
+  SRpcHeader*  pHeader = rpcHeaderFromCont(pCont);
   int32_t      overhead = sizeof(int32_t) * 2;
   int32_t      finalLen = 0;
   
@@ -146,7 +189,7 @@ static int32_t taosCompressRpcMsg(char* pCont, int32_t contLen) {
     return contLen;
   }
   
-  char *buf = malloc (contLen + overhead + 8);  // 16 extra bytes
+  char *buf = malloc (contLen + overhead+8);  // 16 extra bytes
   if (buf == NULL) {
     tError("failed to allocate memory for rpc msg compression, contLen:%d, reason:%s", contLen, strerror(errno));
     return contLen;
@@ -181,131 +224,97 @@ static int32_t taosCompressRpcMsg(char* pCont, int32_t contLen) {
   return finalLen;
 }
 
-static STaosHeader* taosDecompressRpcMsg(STaosHeader* pHeader, SSchedMsg* pSchedMsg, int32_t msgLen) {
+static SRpcHeader *rpcDecompressRpcMsg(SRpcHeader *pHeader) {
   int overhead = sizeof(int32_t) * 2;
+  SRpcHeader *pNewHeader = NULL;  
+  char       *pCont = pHeader->content;
 
-  if (pHeader->comp == 0) {
-    pSchedMsg->msg = (char *)(&(pHeader->destId));
-    return pHeader;
-  }
-  
+  if (pHeader->comp) {
     // decompress the content
     assert(GET_INT32_VAL(pHeader->content) == 0);
   
     // contLen is original message length before compression applied
-  int contLen = htonl(GET_INT32_VAL(pHeader->content + sizeof(int32_t)));
+    int contLen = htonl(GET_INT32_VAL(pCont + sizeof(int32_t)));
   
     // prepare the temporary buffer to decompress message
-  char *buf = malloc(sizeof(STaosHeader) + contLen);
-  
-  //tDump(pHeader->content, msgLen);
+    char *buf = rpcMallocCont(contLen);
   
     if (buf) {
-    int32_t originalLen = LZ4_decompress_safe((const char*)(pHeader->content + overhead), buf + sizeof(STaosHeader),
-        msgLen - overhead, contLen);
-    
-    memcpy(buf, pHeader, sizeof(STaosHeader));
-    free(pHeader); // free the compressed message buffer
-  
-    STaosHeader* pNewHeader = (STaosHeader *) buf;
-    pNewHeader->msgLen = originalLen + (int) sizeof(SIntMsg);
+      pNewHeader = rpcHeaderFromCont(buf);
+      int compLen = rpcContLenFromMsg(pHeader->msgLen) - overhead;
+      int32_t originalLen = LZ4_decompress_safe((const char*)(pCont + overhead), buf, compLen, contLen);
       assert(originalLen == contLen);
     
-    pSchedMsg->msg = (char *)(&(pNewHeader->destId));
-    //tDump(pHeader->content, contLen);
-    return pNewHeader;
+      memcpy(pNewHeader, pHeader, sizeof(SRpcHeader));
+      pNewHeader->msgLen = rpcMsgLenFromCont(originalLen);
+      free(pHeader); // free the compressed message buffer
+      pHeader = pNewHeader; 
     } else {
       tError("failed to allocate memory to decompress msg, contLen:%d, reason:%s", contLen, strerror(errno));
-    pSchedMsg->msg = NULL;
+    }
   }
 
-  return NULL;
+  return pHeader;
 }
 
-char *taosBuildReqHeader(void *param, char type, char *msg) {
-  STaosHeader *pHeader;
-  SRpcConn *   pConn = (SRpcConn *)param;
+char *rpcMallocCont(int size) {
+  char *pMsg = NULL;
 
-  if (pConn == NULL || pConn->signature != pConn) {
-    tError("pConn:%p, connection has to be openned first before building a message", pConn);
+  size += RPC_MSG_OVERHEAD;
+  pMsg = (char *)calloc(1, (size_t)size);
+  if (pMsg == NULL) {
+    tError("failed to malloc msg, size:%d", size);
     return NULL;
   }
 
-  pHeader = (STaosHeader *)(msg + sizeof(SMsgNode));
-  memset(pHeader, 0, sizeof(STaosHeader));
-  pHeader->version = 1;
-  pHeader->comp = 0;
-  pHeader->msgType = type;
-  pHeader->spi = 0;
-  pHeader->tcp = 0;
-  pHeader->encrypt = 0;
-  pHeader->tranId = atomic_add_fetch_16(&pConn->tranId, 1);
-  if (pHeader->tranId == 0) pHeader->tranId = atomic_add_fetch_16(&pConn->tranId, 1);
-
-  pHeader->sourceId = pConn->ownId;
-  pHeader->destId = pConn->peerId;
-  pHeader->port = 0;
-
-  pHeader->uid = (uint32_t)((int64_t)pConn + (int64_t)getpid());
+  return pMsg + sizeof(SRpcReqContext) + sizeof(SRpcHeader);
+}
 
-  memcpy(pHeader->meterId, pConn->meterId, tListLen(pHeader->meterId));
+void rpcFreeCont(char *cont) {
+  char *msg = cont - sizeof(SRpcHeader);
+  free(msg);
+}
 
-  return (char *)pHeader->content;
+static void rpcFreeMsg(char *msg) {
+  msg -= sizeof(SRpcReqContext);
+  free(msg);
 }
 
-char *taosBuildReqMsgWithSize(void *param, char type, int size) {
-  STaosHeader *pHeader;
-  char *       pMsg;
-  SRpcConn *   pConn = (SRpcConn *)param;
+void rpcSendSimpleRsp(void *thandle, int_32 code) {
+  char     *pMsg;
+  STaosRsp *pRsp;
+  int       msgLen = sizeof(STaosRsp);
 
-  if (pConn == NULL || pConn->signature != pConn) {
-    tError("pConn:%p, connection has to be openned first before building a message", pConn);
-    return NULL;
+  if (thandle == NULL) {
+    tError("connection is gone, response could not be sent");
+    return;
   }
 
-  size += sizeof(SMsgNode) + sizeof(STaosHeader) + sizeof(STaosDigest);
-  pMsg = (char *)malloc((size_t)size);
-  memset(pMsg, 0, (size_t)size);
-  pHeader = (STaosHeader *)(pMsg + sizeof(SMsgNode));
-  pHeader->version = 1;
-  pHeader->msgType = type;
-  pHeader->spi = 0;
-  pHeader->tcp = 0;
-  pHeader->encrypt = 0;
-  pHeader->tranId = atomic_add_fetch_32(&pConn->tranId, 1);
-  if (pHeader->tranId == 0) pHeader->tranId = atomic_add_fetch_32(&pConn->tranId, 1);
+  pMsg = rpcMallocCont(msgLen);
+  if (pMsg == NULL) return;
 
-  pHeader->sourceId = pConn->ownId;
-  pHeader->destId = pConn->peerId;
+  pRsp = (STaosRsp *)pMsg;
+  pRsp->code = htonl(code);
 
-  pHeader->uid = (uint32_t)((int64_t)pConn + (int64_t)getpid());
+  taosSendResponse(thandle, pMsg, msgLen);
 
-  memcpy(pHeader->meterId, pConn->meterId, tListLen(pHeader->meterId));
-
-  return (char *)pHeader->content;
+  return;
 }
 
-char *taosBuildRspMsgWithSize(void *param, char type, int size) {
-  STaosHeader *pHeader;
-  char *       pMsg;
-  SRpcConn *   pConn = (SRpcConn *)param;
-
-  if (pConn == NULL || pConn->signature != pConn) {
-    tError("pConn:%p, connection has to be opened first before building a message", pConn);
-    return NULL;
-  }
+static void rpcSendQuickRsp(SRpcConn *pConn, char code) {
+  char         msg[RPC_MSG_OVERHEAD + sizeof(STaosRsp)];
+  SRpcHeader  *pHeader;
+  int          msgLen;
 
-  size += sizeof(SMsgNode) + sizeof(STaosHeader) + sizeof(STaosDigest);
-  pMsg = (char *)malloc((size_t)size);
-  if (pMsg == NULL) {
-    tError("pConn:%p, malloc(%d) failed when building a type:%d message", pConn, size, type);
-    return NULL;
-  }
+  pRsp = (STaosRsp *)rpcContFromHeader(msg);
+  pRsp->code = htonl(code);
+  msgLen = sizeof(STaosRsp);
 
-  memset(pMsg, 0, (size_t)size);
-  pHeader = (STaosHeader *)pMsg;
+  // set msg header
+  memset(msg, 0, sizeof(SRpcHeader));
+  pHeader = (SRpcHeader *)msg;
   pHeader->version = 1;
-  pHeader->msgType = type;
+  pHeader->msgType = pConn->inType+1;
   pHeader->spi = 0;
   pHeader->tcp = 0;
   pHeader->encrypt = 0;
@@ -315,334 +324,240 @@ char *taosBuildRspMsgWithSize(void *param, char type, int size) {
   pHeader->uid = 0;
   memcpy(pHeader->meterId, pConn->meterId, tListLen(pHeader->meterId));
 
-  return (char *)pHeader->content;
-}
-
-int taosSendSimpleRsp(void *thandle, char rsptype, char code) {
-  char *pMsg, *pStart;
-  int   msgLen;
-
-  if (thandle == NULL) {
-    tError("connection is gone, response could not be sent");
-    return -1;
-  }
-
-  pStart = taosBuildRspMsgWithSize(thandle, rsptype, 32);
-  if (pStart == NULL) {
-    tError("build rsp msg error, return null prt");
-    return -1;
-  }
-  pMsg = pStart;
-
-  *pMsg = code;
-  pMsg++;
-
-  msgLen = (int)(pMsg - pStart);
-  taosSendMsgToPeer(thandle, pStart, msgLen);
-
-  return msgLen;
+  rpcSendDataToPeer(pConn, (char *)msg, msgLen);
 }
 
-int taosSendQuickRsp(void *thandle, char rsptype, char code) {
-  char *       pCont;
-  int          contLen;
-  STaosHeader *pHeader;
-  char *       msg;
-  int          msgLen;
-  SRpcConn *   pConn = (SRpcConn *)thandle;
+void *rpcOpen(SRpcInit *pInit) {
+  SRpcInfo *pRpc;
 
-  pCont = taosBuildRspMsgWithSize(thandle, rsptype, 32);
-  if (pCont == NULL) return 0;
-
-  *pCont = code;
-  contLen = 1;
+  tsRpcMaxRetry = tsRpcMaxTime * 1000 / tsRpcProgressTime;
+  tsRpcHeadSize = RPC_MSG_OVERHEAD; 
 
-  pHeader = (STaosHeader *)(pCont - sizeof(STaosHeader));
-  msg = (char *)pHeader;
-  msgLen = contLen + (int32_t)sizeof(STaosHeader);
+  pRpc = (SRpcInfo *)calloc(1, sizeof(SRpcInfo));
+  if (pRpc == NULL) return NULL;
 
-  if (pConn->spi) {
-    // add auth part
-    pHeader->spi = pConn->spi;
-    STaosDigest *pDigest = (STaosDigest *)(pCont + contLen);
-    pDigest->timeStamp = htonl(taosGetTimestampSec());
-    msgLen += sizeof(STaosDigest);
-    pHeader->msgLen = (int32_t)htonl((uint32_t)msgLen);
-    taosBuildAuthHeader((uint8_t *)pHeader, msgLen - TSDB_AUTH_LEN, pDigest->auth, pConn->secret);
-  } else {
-    pHeader->msgLen = (int32_t)htonl((uint32_t)msgLen);
+  strcpy(pRpc->label, pInit->label);
+  pRpc->fp = pInit->fp;
+  pRpc->type = pInit->connType;
+  pRpc->idleTime = pInit->idleTime;
+  pRpc->numOfThreads = pInit->numOfThreads;
+  if (pRpc->numOfThreads > TSDB_MAX_RPC_THREADS) {
+    pRpc->numOfThreads = TSDB_MAX_RPC_THREADS;
   }
 
-  tfree(pConn->pQuickRsp);
-  pConn->pQuickRsp = msg;
-  taosSendDataToPeer(pConn, (char *)pHeader, msgLen);
-
-  return msgLen;
-}
-
-void *taosOpenRpc(SRpcInit *pRpc) {
-  STaosRpc *pServer;
+  pRpc->localPort = pInit->localPort;
+  pRpc->afp = pInit->afp;
+  pRpc->sessions = pInit->session;
+  strcpy(pRpc->meterId, pInit->meterId);
+  pRpc->spi = pInit->spi;
+  strcpy(pRpc->secret, pInit->secret);
+  strcpy(pRpc->ckey, pInit->ckey);
+  pRpc->afp = pInit->afp;
+
+  pRpc->shandle = (*taosInitConn[pRpc->connType])(pRpc->localIp, pRpc->localPort, pRpc->label, pRpc->numOfThreads,
+                                                     taosProcessDataFromPeer, pRpc);
+  if (pRpc->shandle == NULL) {
+    tError("%s failed to init network, %s:%d", pRpc->label, pRpc->localIp, pRpc->localPort);
+    taosCloseRpc(pRpc);
+    return NULL;
+  }
 
-  tsRpcMaxRetry = tsRpcMaxTime * 1000 / tsRpcProgressTime;
-  tsRpcHeadSize = sizeof(STaosHeader) + sizeof(SMsgNode);
-
-  pServer = (STaosRpc *)malloc(sizeof(STaosRpc));
-  if (pServer == NULL) return NULL;
-  memset(pServer, 0, sizeof(STaosRpc));
-
-  pServer->bits = pRpc->bits;
-  pServer->mask = (1 << (pRpc->bits)) - 1;
-  pServer->numOfChanns = pRpc->numOfChanns;
-  strcpy(pServer->label, pRpc->label);
-  pServer->fp = pRpc->fp;
-  pServer->idMgmt = pRpc->idMgmt;
-  pServer->type = pRpc->connType;
-  pServer->idleTime = pRpc->idleTime;
-  pServer->noFree = pRpc->noFree;
-  pServer->numOfThreads = pRpc->numOfThreads;
-  if (pServer->numOfThreads > TSDB_MAX_RPC_THREADS) {
-    pServer->numOfThreads = TSDB_MAX_RPC_THREADS;
-    pRpc->numOfThreads = TSDB_MAX_RPC_THREADS;
+  size_t size = sizeof(SRpcConn) * sessions;
+  pRpc->connList = (SRpcConn *)calloc(1, size);
+  if (pRpc->connList == NULL) {
+    tError("%s failed to allocate memory for taos connections, size:%d", pRpc->label, size);
+    taosCloseRpc(pRpc);
+    return NULL;
   }
-  pServer->localPort = pRpc->localPort;
-  pServer->qhandle = pRpc->qhandle;
-  pServer->efp = pRpc->efp;
-  pServer->afp = pRpc->afp;
 
-  int size = (int)sizeof(SRpcChann) * pRpc->numOfChanns;
-  pServer->channList = (SRpcChann *)malloc((size_t)size);
-  if (pServer->channList == NULL) {
-    tError("%s, failed to malloc channList", pRpc->label);
-    tfree(pServer);
+  pRpc->idPool = taosInitIdPool(sessions);
+  if (pRpc->idPool == NULL) {
+    tError("%s failed to init ID pool", pRpc->label);
+    taosCloseRpc(pRpc);
     return NULL;
   }
-  memset(pServer->channList, 0, (size_t)size);
 
-  pServer->shandle = (*taosInitConn[pRpc->connType])(pRpc->localIp, pRpc->localPort, pRpc->label, pRpc->numOfThreads,
-                                                     taosProcessDataFromPeer, pServer);
-  if (pServer->shandle == NULL) {
-    tError("%s, failed to init network, %s:%d", pRpc->label, pRpc->localIp, pRpc->localPort);
-    taosCloseRpc(pServer);
+  pRpc->tmrCtrl = taosTmrInit(sessions * 2 + 1, 50, 10000, pRpc->label);
+  if (pRpc->tmrCtrl == NULL) {
+    tError("%s failed to init timers", pRpc->label);
+    taosCloseRpc(pRpc);
     return NULL;
   }
 
-  if (pServer->numOfChanns == 1) {
-    int retVal = taosOpenRpcChann(pServer, 0, pRpc->sessionsPerChann);
-    if (0 != retVal) {
-      tError("%s, failed to open rpc chann", pRpc->label);
-      taosCloseRpc(pServer);
+  pRpc->hash = taosInitStrHash(sessions, sizeof(pRpc), taosHashString);
+  if (pRpc->hash == NULL) {
+    tError("%s failed to init string hash", pRpc->label);
+    taosCloseRpc(pRpc);
     return NULL;
   }
+
+  pRpc->pCahche = taosOpenConnCache(pRpc->sessions, rpcCloseConn, pRpc->tmrCtrl, tsShellActivityTimer*1000); 
+  if ( pRpc->pCache == NULL ) {
+    tError("%s failed to init connection cache", pRpc->label);
+    taosCloseRpc(pRpc);
+    return NULL;
   }
 
+  pthread_mutex_init(&pRpc->mutex, NULL);
+
   tTrace("%s RPC is openned, numOfThreads:%d", pRpc->label, pRpc->numOfThreads);
 
-  return pServer;
+  return pRpc;
 }
 
-int taosOpenRpcChannWithQ(void *handle, int cid, int sessions, void *qhandle) {
-  STaosRpc * pServer = (STaosRpc *)handle;
-  SRpcChann *pChann;
-
-  tTrace("cid:%d, handle:%p open rpc chann", cid, handle);
+void rpcClose(void *param) {
+  SRpcInfo *pRpc = (SRpcInfo *)param;
 
-  if (pServer == NULL) return -1;
-  if (cid >= pServer->numOfChanns || cid < 0) {
-    tError("%s: cid:%d, chann is out of range, max:%d", pServer->label, cid, pServer->numOfChanns);
-    return -1;
-  }
-
-  pChann = pServer->channList + cid;
-  memset(pChann, 0, sizeof(SRpcChann));
-
-  size_t size = sizeof(SRpcConn) * sessions;
-  pChann->connList = (SRpcConn *)calloc(1, size);
-  if (pChann->connList == NULL) {
-    tError("%s cid:%d, failed to allocate memory for taos connections, size:%d", pServer->label, cid, size);
-    return -1;
-  }
-
-  if (pServer->idMgmt == TAOS_ID_FREE) {
-    pChann->idPool = taosInitIdPool(sessions);
-    if (pChann->idPool == NULL) {
-      tError("%s cid:%d, failed to init ID pool", pServer->label, cid);
-      return -1;
-    }
-  }
+  (*taosCleanUpConn[pRpc->type])(pRpc->shandle);
 
-  pChann->tmrCtrl = taosTmrInit(sessions * 2 + 1, 50, 10000, pServer->label);
-  if (pChann->tmrCtrl == NULL) {
-    tError("%s cid:%d, failed to init timers", pServer->label, cid);
-    return -1;
+  for (int i = 0; i < pRpc->sessions; ++i) {
+    if (pRpc->connList[i].signature != NULL) {
+      taosCloseRpcConn((void *)(pRpc->connList + i));
     }
-
-  pChann->hash = taosInitStrHash(sessions, sizeof(pChann), taosHashString);
-  if (pChann->hash == NULL) {
-    tError("%s cid:%d, failed to init string hash", pServer->label, cid);
-    return -1;
   }
 
-  pthread_mutex_init(&pChann->mutex, NULL);
-  pChann->sessions = sessions;
-
-  pChann->qhandle = qhandle ? qhandle : pServer->qhandle;
+  taosCleanUpStrHash(pRpc->hash);
+  taosTmrCleanUp(pRpc->tmrCtrl);
+  taosIdPoolCleanUp(pRpc->idPool);
+  taosCloseConnCache(pRpc->pCache);
 
-  return TSDB_CODE_SUCCESS;
+  tfree(pRpc->connList);
+  pthread_mutex_destroy(&pRpc->mutex);
+  tfree(pRpc);
 }
 
-void taosCloseRpcChann(void *handle, int cid) {
-  STaosRpc * pServer = (STaosRpc *)handle;
-  SRpcChann *pChann;
-
-  tTrace("cid:%d, handle:%p close rpc chann", cid, handle);
+static SRpcConn *rpcOpenConn(SRpcConnInit *pInit) {
+  SRpcConn *pConn;
+  SRpcInfo *pRpc = (SRpcInfo *)pInit->shandle;
 
-  if (pServer == NULL) return;
-  if (cid >= pServer->numOfChanns || cid < 0) {
-    tError("%s cid:%d, chann is out of range, max:%d", pServer->label, cid, pServer->numOfChanns);
-    return;
-  }
+  if ( (uint8_t)(rpcGetConn(pInit->sid, pInit->meterId, pRpc, &pConn, 1, NULL)) != 0 ) 
+    return NULL;
 
-  pChann = pServer->channList + cid;
+  if (pConn->peerId == 0) pConn->peerId = pRpc->peerId;
+  strcpy(pConn->peerIpstr, pInit->peerIp);
+  pConn->peerIp = inet_addr(pInit->peerIp);
+  pConn->peerPort = pInit->peerPort;
+  pConn->ahandle = pInit->ahandle;
+  pConn->spi = pRpc->spi;
+  pConn->encrypt = pRpc->encrypt;
+  if (pConn->spi) memcpy(pConn->secret, pRpc->secret, TSDB_KEY_LEN);
 
-  for (int i = 0; i < pChann->sessions; ++i) {
-    if (pChann->connList[i].signature != NULL) {
-      taosCloseRpcConn((void *)(pChann->connList + i));
+  // if it is client, it shall set up connection first
+  if (taosOpenConn[pRpc->type]) {
+    pConn->chandle = (*taosOpenConn[pRpc->type])(pRpc->shandle, pConn, pConn->peerIpstr, pConn->peerPort);
+    if (pConn->chandle) {
+      tTrace("%s pConn:%p, rpc connection is set up, sid:%d id:%s ip:%s:%hu localPort:%d", pRpc->label, 
+              pConn, pConn->sid, pInit->meterId, pConn->peerIpstr, pConn->peerPort, pConn->localPort);
+    } else {
+      tError("%s pConn:%p, failed to set up nw connection to ip:%s:%hu", pRpc->label, pConn,
+             pConn->sid, pInit->meterId, pConn->peerIpstr, pConn->peerPort);
+      terrorno = TSDB_CODE_NETWORK_UNAVAIL;
+      rpcCloseConn(pConn);
+      pConn = NULL;
     }
   }
 
-  taosCleanUpStrHash(pChann->hash);
-  taosTmrCleanUp(pChann->tmrCtrl);
-  taosIdPoolCleanUp(pChann->idPool);
-  tfree(pChann->connList);
-  pthread_mutex_destroy(&pChann->mutex);
-
-  memset(pChann, 0, sizeof(SRpcChann));
+  return pConn;
 }
 
-void taosCloseRpcConn(void *thandle) {
+static void rpcCloseConn(void *thandle) {
   SRpcConn *pConn = (SRpcConn *)thandle;
   if (pConn == NULL) return;
 
-  STaosRpc *pServer = pConn->pServer;
-  if (pConn->signature != thandle || pServer == NULL) return;
-  if (pConn->closing) return;
-  SRpcChann *pChann = pServer->channList + pConn->chann;
+  SRpcInfo *pRpc = pConn->pRpc;
+  if (pConn->signature != thandle || pRpc == NULL) return;
 
-  pthread_mutex_lock(&pChann->mutex);
+  pthread_mutex_lock(&pRpc->mutex);
 
-  pConn->closing = 1;
   pConn->signature = NULL;
 
-  if (taosCloseConn[pServer->type]) (*taosCloseConn[pServer->type])(pConn->chandle);
+  if (taosCloseConn[pRpc->type]) (*taosCloseConn[pRpc->type])(pConn->chandle);
 
   taosTmrStopA(&pConn->pTimer);
   taosTmrStopA(&pConn->pIdleTimer);
-  tfree(pConn->pRspMsg);
-
-  if (pServer->noFree == 0) free(pConn->pMsgNode);
-  pConn->pMsgNode = NULL;
-
-  tfree(pConn->pQuickRsp);
-
-  SMsgNode *pMsgNode;
-  while (pConn->pHead) {
-    pMsgNode = pConn->pHead;
-    pConn->pHead = pConn->pHead->next;
-    memset(pMsgNode, 0, sizeof(SMsgNode));
-    if (pServer->noFree == 0) free(pMsgNode);
-  }
+  rpcFreeMsg(pConn->pRspMsg);
+  rpcFreeMsg(pConn-pReqMsg);
 
   char hashstr[40] = {0};
   sprintf(hashstr, "%x:%x:%x", pConn->peerIp, pConn->peerUid, pConn->peerId);
-  taosDeleteStrHash(pChann->hash, hashstr);
+  taosDeleteStrHash(pRpc->hash, hashstr);
 
-  tTrace("%s cid:%d sid:%d id:%s, TAOS connection closed, pConn:%p", pServer->label, pConn->chann, pConn->sid,
+  tTrace("%s pConn:%p, TAOS connection closed", pRpc->label, pConn->sid,
          pConn->meterId, pConn);
   int freeId = pConn->sid;
   memset(pConn, 0, sizeof(SRpcConn));
 
-  if (pChann->idPool) taosFreeId(pChann->idPool, freeId);
+  if (pRpc->idPool) taosFreeId(pRpc->idPool, freeId);
 
-  pthread_mutex_unlock(&pChann->mutex);
+  pthread_mutex_unlock(&pRpc->mutex);
 }
 
-int taosGetRpcConn(int chann, int sid, char *meterId, STaosRpc *pServer, SRpcConn **ppConn, char req, char *hashstr) {
+static int rpcGetConn(int sid, char *meterId, SRpcInfo *pRpc, SRpcConn **ppConn, char req, char *hashstr) {
   SRpcConn * pConn = NULL;
-  SRpcChann *pChann;
 
-  if (pServer == NULL) return -1;
-  pChann = pServer->channList + chann;
+  if (pRpc == NULL) return -1;
 
-  if (pServer->idMgmt == TAOS_ID_FREE) {
   if (sid == 0) {
     if (req) {
       int        osid = sid;
-        SRpcConn **ppConn = (SRpcConn **)taosGetStrHashData(pChann->hash, hashstr);
+      SRpcConn **ppConn = (SRpcConn **)taosGetStrHashData(pRpc->hash, hashstr);
       if (ppConn) pConn = *ppConn;
       if (pConn == NULL) {
-          sid = taosAllocateId(pChann->idPool);
+        sid = taosAllocateId(pRpc->idPool);
         if (sid <= 0) {
-            tError("%s cid:%d, maximum number of sessions:%d is reached", pServer->label, chann, pChann->sessions);
+          tError("%s maximum number of sessions:%d is reached", pRpc->label, pRpc->sessions);
           return TSDB_CODE_MAX_SESSIONS;
         } else {
-            tTrace("%s cid:%d sid:%d, ID allocated, used:%d, old id:%d", pServer->label, chann, sid,
-                   taosIdPoolNumOfUsed(pChann->idPool), osid);
+          tTrace("%s sid:%d, ID allocated, used:%d, old id:%d", pRpc->label, sid,
+                 taosIdPoolNumOfUsed(pRpc->idPool), osid);
         }
       } else {
         sid = pConn->sid;
-          tTrace("%s cid:%d sid:%d id:%s, session is already there", pServer->label, pConn->chann, pConn->sid,
+        tTrace("%s sid:%d id:%s, session is already there", pRpc->label, pConn->sid,
                pConn->meterId);
       }
     } else {
       return TSDB_CODE_UNEXPECTED_RESPONSE;
     }
   } else {
-      if (pChann->connList[sid].signature == NULL) {
-        tError("%s cid:%d, sid:%d session is already released", pServer->label, chann, sid);
+    if (pRpc->connList[sid].signature == NULL) {
+      tError("%s sid:%d session is already released", pRpc->label, sid);
       return TSDB_CODE_INVALID_VALUE;
     }
   } 
-  }
 
-  pConn = pChann->connList + sid;
-  if (pChann == NULL || pChann->connList == NULL) {
-    tTrace("%s cid:%d sid:%d, connlist is null, received:%s", pServer->label, chann, sid, meterId);
-    return TSDB_CODE_MISMATCHED_METER_ID;
-  }
+  pConn = pRpc->connList + sid;
 
   if (pConn->signature == NULL) {
     memset(pConn, 0, sizeof(SRpcConn));
     pConn->signature = pConn;
     memcpy(pConn->meterId, meterId, tListLen(pConn->meterId));
-    pConn->pServer = pServer;
-    pConn->chann = chann;
+    pConn->pRpc = pRpc;
     pConn->sid = sid;
     pConn->tranId = (uint16_t)(rand() & 0xFFFF);
-    pConn->ownId = htonl((uint32_t)((pConn->chann << pServer->bits) + pConn->sid));
-    if (pServer->afp) {
-      int ret = (*pServer->afp)(meterId, &pConn->spi, &pConn->encrypt, pConn->secret, pConn->ckey);
+    pConn->ownId = htonl(pConn->sid);
+    if (pRpc->afp) {
+      int ret = (*pRpc->afp)(meterId, &pConn->spi, &pConn->encrypt, pConn->secret, pConn->ckey);
       if (ret != 0) {
-        tWarn("%s cid:%d sid:%d id:%s, meterId not there pConn:%p", pServer->label, chann, sid, pConn->meterId, pConn);
-        taosFreeId(pChann->idPool, sid);   // sid shall be released
+        tWarn("%s pConn:%p, meterId not there", pRpc->label, pConn);
+        taosFreeId(pRpc->idPool, sid);   // sid shall be released
         memset(pConn, 0, sizeof(SRpcConn)); 
         return ret;
       }
     }
 
-    if ((pServer->type == TAOS_CONN_UDPC || pServer->type == TAOS_CONN_UDPS) && pServer->numOfThreads > 1 &&
-        pServer->localPort) {
+    if ((pRpc->type == TAOS_CONN_UDPC || pRpc->type == TAOS_CONN_UDPS) && pRpc->numOfThreads > 1 &&
+        pRpc->localPort) {
       // UDP server, assign to new connection
-      pServer->index = (pServer->index + 1) % pServer->numOfThreads;
-      pConn->localPort = (int16_t)(pServer->localPort + pServer->index);
+      pRpc->index = (pRpc->index + 1) % pRpc->numOfThreads;
+      pConn->localPort = (int16_t)(pRpc->localPort + pRpc->index);
     }
 
-    taosAddStrHash(pChann->hash, hashstr, (char *)&pConn);
-    tTrace("%s cid:%d sid:%d id:%s, TAOS connection is allocated, localPort:%d pConn:%p", pServer->label, chann, sid,
-           pConn->meterId, pConn->localPort, pConn);
+    taosAddStrHash(pRpc->hash, hashstr, (char *)&pConn);
+    tTrace("%s pConn:%p, TAOS connection is allocated, sid:%d id:%s", pRpc->label, pConn, sid);
   } else {
     if (memcmp(pConn->meterId, meterId, tListLen(pConn->meterId)) != 0) {
-      tTrace("%s cid:%d sid:%d id:%s, meterId is not matched, received:%s", pServer->label, chann, sid, pConn->meterId,
-             meterId);
+      tTrace("%s pConn:%p, meterId:%s is not matched, received:%s", pRpc->label, pConn, pConn->meterId, meterId);
       return TSDB_CODE_MISMATCHED_METER_ID;
     }
   }
@@ -652,215 +567,159 @@ int taosGetRpcConn(int chann, int sid, char *meterId, STaosRpc *pServer, SRpcCon
   return TSDB_CODE_SUCCESS;
 }
 
-void *taosOpenRpcConn(SRpcConnInit *pInit, uint8_t *code) {
-  SRpcConn *pConn;
-  STaosRpc *pServer = (STaosRpc *)pInit->shandle;
-
-  *code = (uint8_t)(taosGetRpcConn(pInit->cid, pInit->sid, pInit->meterId, pServer, &pConn, 1, NULL));
-  if (*code == TSDB_CODE_MAX_SESSIONS) *code = TSDB_CODE_MAX_CONNECTIONS;
-  if (*code != TSDB_CODE_SUCCESS) return NULL;
+static int rpcCheckAuthentication(SRpcConn *pConn, char *msg, int msgLen) {
+  SRpcHeader *pHeader = (SRpcHeader *)msg;
+  SRpcInfo    *pRpc = pConn->pRpc;
+  int          code = 0;
 
-  if (pConn->peerId == 0) pConn->peerId = pInit->peerId;
+  if (pConn->spi == 0 ) return 0;
 
-  strcpy(pConn->peerIpstr, pInit->peerIp);
-  pConn->peerIp = inet_addr(pInit->peerIp);
-  pConn->peerPort = pInit->peerPort;
-  pConn->ahandle = pInit->ahandle;
-  pConn->spi = pInit->spi;
-  pConn->encrypt = pInit->encrypt;
-  if (pConn->spi) memcpy(pConn->secret, pInit->secret, TSDB_KEY_LEN);
+  if (pHeader->spi == pConn->spi) {
+    // authentication
+    SRpcDigest *pDigest = (SRpcDigest *)((char *)pHeader + msgLen - sizeof(SRpcDigest));
 
-  // if it is client, it shall set up connection first
-  if (taosOpenConn[pServer->type]) {
-    pConn->chandle = (*taosOpenConn[pServer->type])(pServer->shandle, pConn, pConn->peerIpstr, pConn->peerPort);
-    if (pConn->chandle) {
-      tTrace("%s cid:%d sid:%d id:%s, nw connection is set up, ip:%s:%hu localPort:%d pConn:%p", pServer->label,
-             pConn->chann, pConn->sid, pInit->meterId, pConn->peerIpstr, pConn->peerPort, pConn->localPort, pConn);
+    int32_t delta;
+    delta = (int32_t)htonl(pDigest->timeStamp);
+    delta -= (int32_t)taosGetTimestampSec();
+    if (abs(delta) > 900) {
+      tWarn("%s pConn:%p, time diff:%d is too big, msg discarded, timestamp:%d", pRpc->label, pConn,
+             delta, htonl(pDigest->timeStamp));
+      code = TSDB_CODE_INVALID_TIME_STAMP;
     } else {
-      tError("%s cid:%d sid:%d id:%s, failed to set up nw connection to ip:%s:%hu", pServer->label, pConn->chann,
-             pConn->sid, pInit->meterId, pConn->peerIpstr, pConn->peerPort);
-      *code = TSDB_CODE_NETWORK_UNAVAIL;
-      taosCloseRpcConn(pConn);
-      pConn = NULL;
+      if (rpcAuthenticateMsg((uint8_t *)pHeader, dataLen - TSDB_AUTH_LEN, pDigest->auth, pConn->secret) < 0) {
+        char ipstr[24];
+        tinet_ntoa(ipstr, ip);
+        mLError("id:%s from %s, authentication failed", pHeader->meterId, ipstr);
+        tError("%s pConn:%p, authentication failed, msg discarded", pRpc->label, pConn);
+        code = TSDB_CODE_AUTH_FAILURE;
+      } else {
+        pHeader->msgLen -= sizeof(SRpcDigest);
       }
     }
-
-  return pConn;
-}
-
-void taosCloseRpc(void *param) {
-  STaosRpc *pServer = (STaosRpc *)param;
-
-  (*taosCleanUpConn[pServer->type])(pServer->shandle);
-
-  for (int cid = 0; cid < pServer->numOfChanns; ++cid) taosCloseRpcChann(pServer, cid);
-
-  tfree(pServer->channList);
-  tfree(pServer);
-}
-
-int taosSetSecurityInfo(int chann, int sid, char *id, int spi, int encrypt, char *secret, char *ckey) {
-  /*
-    SRpcConn *pConn;
-
-    pConn = connList[chann*tsSessionsPerChann + sid];
-
-    if ( pConn == NULL ) {
-      pConn = (SRpcConn *)sizeof(SRpcConn);
-
-      if ( pConn == NULL ) {
-        tError("failed to allocate memory for taosConn");
-        return -1;
+  } else {
+    // if it is request or response with code 0, msg shall be discarded
+    if (rpcIsReq(pHeader->msgType) || (pHeader->content[0] == 0)) {
+      tTrace("%s pConn:%p, auth spi not matched, msg discarded", pRpc->label, pConn);
+      code = TSDB_CODE_AUTH_FAILURE;
     }
-
-      memset(pConn, 0, sizeof(SRpcConn));
-      pConn->chann = chann;
-      pConn->sid = sid;
   }
 
-    pConn->spi = spi;
-    pConn->encrypt = encrypt;
-    memcpy(pConn->secret, pConn->secret, TSDB_KEY_LEN);
-    memcpy(pConn->cipheringKey, ckey, TSDB_KEY_LEN);
-    memcpy(pConn->meterId, id, TSDB_TABLE_ID_LEN);
-  */
-  return -1;
+  return code;
 }
 
-int taosSendDataToPeer(SRpcConn *pConn, char *data, int dataLen) {
-  int          writtenLen = 0;
-  STaosRpc *   pServer = pConn->pServer;
-  STaosHeader *pHeader = (STaosHeader *)data;
+static int rpcProcessReqHeader(SRpcConn *pConn, SRpcHeader *pHeader) {
+    int code = 0;
 
-  if (pConn->signature != pConn || pServer == NULL) return -1;
+    if (pConn->peerId == 0) {
+      pConn->peerId = pHeader->sourceId;
+    } else {
+      if (pConn->peerId != pHeader->sourceId) {
+        tTrace("%s pConn:%p, source Id is changed, old:0x%08x new:0x%08x", pRpc->label, pConn, 
+               pConn->peerId, pHeader->sourceId);
+        return TSDB_CODE_INVALID_VALUE;
+      }
+    }
 
-  if (pHeader->msgType & 1) {
-    if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16))
-      tTrace("%s cid:%d sid:%d id:%s, %s is sent to %s:%hu, len:%d source:0x%08x dest:0x%08x tranId:%d pConn:%p",
-             pServer->label, pConn->chann, pConn->sid, pConn->meterId, taosMsg[pHeader->msgType], pConn->peerIpstr,
-             pConn->peerPort, dataLen, pHeader->sourceId, pHeader->destId, pHeader->tranId, pConn);
+    if (pConn->inTranId == pHeader->tranId) {
+      if (pConn->inType == pHeader->msgType) {
+        tTrace("%s pConn:%p, %s is retransmitted", pRpc->label, pConn, taosMsg[pHeader->msgType]);
+        taosSendQuickRsp(pConn, TSDB_CODE_ACTION_IN_PROGRESS);
+      } else if (pConn->inType == 0) {
+        tTrace("%s pConn:%p, %s is already processed, tranId:%d", pRpc->label, pConn, 
+                taosMsg[pHeader->msgType], pConn->inTranId);
+        rpcResendRspToPeer(pConn);
       } else {
-    if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16))
-      tTrace(
-          "%s cid:%d sid:%d id:%s, %s is sent to %s:%hu, code:%u len:%d source:0x%08x dest:0x%08x tranId:%d pConn:%p",
-          pServer->label, pConn->chann, pConn->sid, pConn->meterId, taosMsg[pHeader->msgType], pConn->peerIpstr,
-          pConn->peerPort, (uint8_t)pHeader->content[0], dataLen, pHeader->sourceId, pHeader->destId, pHeader->tranId,
-          pConn);
+        tTrace("%s pConn:%p, mismatched message %s and tranId", pRpc->label, pConn, taosMsg[pHeader->msgType]);
       }
 
-  writtenLen = (*taosSendData[pServer->type])(pConn->peerIp, pConn->peerPort, (char *)pHeader, dataLen, pConn->chandle);
+      // do not reply any message
+      return TSDB_CODE_ALREADY_PROCESSED;
+    }
 
-  if (writtenLen != dataLen)
-    tError("%s cid:%d sid:%d id:%s, dataLen:%d writtenLen:%d, not good, reason:%s", pServer->label, pConn->chann,
-           pConn->sid, pConn->meterId, dataLen, writtenLen, strerror(errno));
-  // assert ( writtenLen == dataLen );
-  tDump(data, dataLen);
+    if (pConn->inType != 0) {
+      tTrace("%s pConn:%p, last session is not finished, inTranId:%d tranId:%d", pRpc->label, pConn,
+             pConn->inTranId, pHeader->tranId);
+      return TSDB_CODE_LAST_SESSION_NOT_FINISHED;
+    }
+
+    pConn->inTranId = pHeader->tranId;
+    pConn->inType = pHeader->msgType;
 
     return 0;
 }
 
-void taosProcessResponse(SRpcConn *pConn) {
-  STaosHeader *pHeader;
-  char *       msg = NULL;
-  int          msgLen = 0;
+static int rpcProcessRspHeader(SRpcConn *pConn, SRpcHeader *pHeader) {
+  pConn->peerId = pHeader->sourceId;
 
-  if (pConn == NULL) return;
-  STaosRpc *pServer = pConn->pServer;
-  if (pConn->signature != pConn || pServer == NULL) return;
-  SRpcChann *pChann = pServer->channList + pConn->chann;
+  if (pConn->outType == 0 || pConn->pContext == NULL) {
+    return TSDB_CODE_UNEXPECTED_RESPONSE;
+  }
 
-  pthread_mutex_lock(&pChann->mutex);
+  if (pHeader->tranId != pConn->outTranId) {
+    return TSDB_CODE_INVALID_TRAN_ID;
+  }
 
-  pConn->outType = 0;
-  pConn->rspReceived = 0;
-  if (pServer->noFree == 0) tfree(pConn->pMsgNode);
-  pConn->pMsgNode = NULL;
-
-  if (pConn->pHead) {
-    SMsgNode *pMsgNode = pConn->pHead;
-    //      assert ( pMsgNode->msgLen >= sizeof(STaosHeader) && pMsgNode->msgLen < RPC_MAX_UDP_SIZE);
-    if (pMsgNode->msgLen >= sizeof(STaosHeader)) {
-      pConn->pMsgNode = pMsgNode;
-      pConn->pHead = pMsgNode->next;
-      if (pMsgNode->ahandle) pConn->ahandle = pMsgNode->ahandle;
+  if (pHeader->msgType != pConn->outType + 1) {
+    return TSDB_CODE_INVALID_RESPONSE_TYPE;
+  }
 
-      pHeader = (STaosHeader *)((char *)pMsgNode + sizeof(SMsgNode));
-      pConn->outType = pHeader->msgType;
-      pConn->outTranId = pHeader->tranId;
+  if (*pHeader->content == TSDB_CODE_NOT_READY) {
+    return = TSDB_CODE_ALREADY_PROCESSED;
+  }
 
-      msg = (char *)pHeader;
-      msgLen = pMsgNode->msgLen;
+  taosTmrStopA(&pConn->pTimer);
+  pConn->retry = 0;
 
+  if (*pHeader->content == TSDB_CODE_ACTION_IN_PROGRESS || pHeader->tcp) {
+    if (pConn->tretry <= tsRpcMaxRetry) {
+      tTrace("%s pConn:%p, peer is still processing the transaction", pRpc->label, pConn);
+      pConn->tretry++;
+      taosTmrReset(rpcProcessRetryTimer, tsRpcProgressTime, pConn, pRpc->tmrCtrl, &pConn->pTimer);
+      return TSDB_CODE_ALREADY_PROCESSED;
     } else {
-      tError("%s cid:%d sid:%d id:%s, invalid msgLen:%d pConn:%p", pServer->label, pConn->chann, pConn->sid,
-             pConn->meterId, pMsgNode->msgLen, pConn);
-      pConn->pHead = NULL;
-    }
-
-    if (pConn->pHead == NULL) pConn->pTail = NULL;
+      // peer still in processing, give up
+      *pHeader->content = TSDB_CODE_TOO_SLOW;
     }
-
-  if (msg) {
-    taosSendDataToPeer(pConn, msg, msgLen);
-    taosTmrReset(taosProcessTaosTimer, tsRpcTimer, pConn, pChann->tmrCtrl, &pConn->pTimer);
   }
 
-  pthread_mutex_unlock(&pChann->mutex);
-
+  pConn->tretry = 0;
+  pConn->outType = 0;
+  pConn->pReqMsg = NULL;
+  pConn->pReqMsgLen = 0;
 }
 
-int taosProcessMsgHeader(STaosHeader *pHeader, SRpcConn **ppConn, STaosRpc *pServer, int dataLen, uint32_t ip,
+static int rpcProcessHeader(SRpcHeader *pHeader, SRpcConn **ppConn, SRpcInfo *pRpc, int dataLen, uint32_t ip,
                          uint16_t port, void *chandle) {
-  int        chann, sid, code = 0;
+  int        sid, code = 0;
   SRpcConn * pConn = NULL;
-  SRpcChann *pChann;
   int        msgLen;
   char       hashstr[40] = {0};
-  // int        reSend = 0;
 
   *ppConn = NULL;
-  uint32_t destId = htonl(pHeader->destId);
-  chann = destId >> pServer->bits;
-  sid = destId & pServer->mask;
+  uint32_t sid = htonl(pHeader->destId);
 
   if (pHeader->msgType >= TSDB_MSG_TYPE_MAX || pHeader->msgType <= 0) {
-    tTrace("%s cid:%d sid:%d, invalid message type:%d", pServer->label, chann, sid, pHeader->msgType);
+    tTrace("%s sid:%d, invalid message type:%d", pRpc->label, sid, pHeader->msgType);
     return TSDB_CODE_INVALID_MSG_TYPE;
   }
 
-  msgLen = (int32_t)htonl((uint32_t)pHeader->msgLen);
-  if (dataLen != msgLen) {
-    tTrace("%s cid:%d sid:%d, %s has invalid length, dataLen:%d, msgLen:%d", pServer->label, chann, sid,
+  pHeader->msgLen = (int32_t)htonl((uint32_t)pHeader->msgLen);
+  if (dataLen != pHeader->msgLen) {
+    tTrace("%s sid:%d, %s has invalid length, dataLen:%d, msgLen:%d", pRpc->label, sid,
            taosMsg[pHeader->msgType], dataLen, msgLen);
     return TSDB_CODE_INVALID_MSG_LEN;
   }
 
-  if (chann < 0 || chann >= pServer->numOfChanns) {
-    tTrace("%s cid:%d sid:%d, chann is out of range, max:%d, %s discarded", pServer->label, chann, sid,
-           pServer->numOfChanns, taosMsg[pHeader->msgType]);
-    return TSDB_CODE_INVALID_SESSION_ID;
-  }
-
-  pChann = pServer->channList + chann;
-  if (pChann->sessions == 0) {
-    tTrace("%s cid:%d, chann is not activated yet, %s discarded", pServer->label, chann, taosMsg[pHeader->msgType]);
-    if (pServer->efp) (*(pServer->efp))(chann);
-    return TSDB_CODE_NOT_ACTIVE_SESSION;
-  }
-
-  if (sid < 0 || sid >= pChann->sessions) {
-    tTrace("%s cid:%d sid:%d, sid is out of range, max sid:%d, %s discarded", pServer->label, chann, sid,
-           pChann->sessions, taosMsg[pHeader->msgType]);
+  if (sid < 0 || sid >= pRpc->sessions) {
+    tTrace("%s sid:%d, sid is out of range, max sid:%d, %s discarded", pRpc->label, sid,
+           pRpc->sessions, taosMsg[pHeader->msgType]);
     return TSDB_CODE_INVALID_SESSION_ID;
   }
 
-  //  if ( pHeader->tcp ) return TSDB_CODE_ALREADY_PROCESSED;
   if (sid == 0) sprintf(hashstr, "%x:%x:%x", ip, pHeader->uid, pHeader->sourceId);
 
-  pthread_mutex_lock(&pChann->mutex);
-
-  code = taosGetRpcConn(chann, sid, pHeader->meterId, pServer, &pConn, pHeader->msgType & 1, hashstr);
-  if (code != TSDB_CODE_SUCCESS) goto _exit;
+  code = rpcGetConn(sid, pHeader->meterId, pRpc, &pConn, rpcIsReq(pHeader->msgType), hashstr);
+  if (code != TSDB_CODE_SUCCESS) return code;
 
   *ppConn = pConn;
   sid = pConn->sid;
@@ -873,175 +732,44 @@ int taosProcessMsgHeader(STaosHeader *pHeader, SRpcConn **ppConn, STaosRpc *pSer
   }
 
   if (pHeader->uid) pConn->peerUid = pHeader->uid;
-
   if (port) pConn->peerPort = port;
-
   if (pHeader->port)  // port maybe changed by the peer
     pConn->peerPort = pHeader->port;
-
   if (chandle) pConn->chandle = chandle;
 
   if (pHeader->tcp) {
-    tTrace("%s cid:%d sid:%d id:%s, content will be transfered via TCP pConn:%p", pServer->label, chann, sid,
-           pConn->meterId, pConn);
-    if (pConn->outType) taosTmrReset(taosProcessTaosTimer, tsRpcTimer, pConn, pChann->tmrCtrl, &pConn->pTimer);
-    code = TSDB_CODE_ALREADY_PROCESSED;
-    goto _exit;
+    tTrace("%s pConn:%p, content will be transfered via TCP", pRpc->label, pConn);
+    if (pConn->outType) taosTmrReset(rpcProcessRetryTimer, tsRpcTimer, pConn, pRpc->tmrCtrl, &pConn->pTimer);
+    return TSDB_CODE_ALREADY_PROCESSED;
   }
 
-  if (pConn->spi != 0) {
-    if (pHeader->spi == pConn->spi) {
-      // authentication
-      STaosDigest *pDigest = (STaosDigest *)((char *)pHeader + dataLen - sizeof(STaosDigest));
-
-      int32_t delta;
-      delta = (int32_t)htonl(pDigest->timeStamp);
-      delta -= (int32_t)taosGetTimestampSec();
-      if (abs(delta) > 900) {
-        tWarn("%s cid:%d sid:%d id:%s, time diff:%d is too big, msg discarded pConn:%p, timestamp:%d", pServer->label,
-              chann, sid, pConn->meterId, delta, pConn, htonl(pDigest->timeStamp));
-        // the requirement of goldwind, should not return error in this case
-        code = TSDB_CODE_INVALID_TIME_STAMP;
-        goto _exit;
-      }
-
-      if (taosAuthenticateMsg((uint8_t *)pHeader, dataLen - TSDB_AUTH_LEN, pDigest->auth, pConn->secret) < 0) {
-        char ipstr[24];
-        tinet_ntoa(ipstr, ip);
-        mLError("user:%s login from %s, authentication failed", pHeader->meterId, ipstr);
-        tError("%s cid:%d sid:%d id:%s, authentication failed, msg discarded pConn:%p", pServer->label, chann, sid,
-               pConn->meterId, pConn);
-        code = TSDB_CODE_AUTH_FAILURE;
-        goto _exit;
-      }
-    } else {
-      // if it is request or response with code 0, msg shall be discarded
-      if ((pHeader->msgType & 1) || (pHeader->content[0] == 0)) {
-        tTrace("%s cid:%d sid:%d id:%s, auth spi not matched, msg discarded pConn:%p", pServer->label, chann, sid,
-               pConn->meterId, pConn);
-        code = TSDB_CODE_AUTH_FAILURE;
-        goto _exit;
-      }
-    }
-  }
+  code = rpcCheckAuthentication(pConn, (char *)pHeader, dataLen);
+  if ( code != 0 ) return code;
 
   if (pHeader->msgType != TSDB_MSG_TYPE_REG && pHeader->encrypt) {
     // decrypt here
   }
 
-  pHeader->destId = pConn->ownId;  // destId maybe 0, it shall be changed
-
-  if (pHeader->msgType & 1) {
-    if (pConn->peerId == 0) {
-      pConn->peerId = pHeader->sourceId;
-    } else {
-      if (pConn->peerId != pHeader->sourceId) {
-        tTrace("%s cid:%d sid:%d id:%s, source Id is changed, old:0x%08x new:0x%08x pConn:%p", pServer->label, chann,
-               sid, pConn->meterId, pConn->peerId, pHeader->sourceId, pConn);
-        code = TSDB_CODE_INVALID_VALUE;
-        goto _exit;
-      }
-    }
-
-    if (pConn->inTranId == pHeader->tranId) {
-      if (pConn->inType == pHeader->msgType) {
-        tTrace("%s cid:%d sid:%d id:%s, %s is retransmitted, pConn:%p", pServer->label, chann, sid, pConn->meterId,
-               taosMsg[pHeader->msgType], pConn);
-        taosSendQuickRsp(pConn, (char)(pHeader->msgType + 1), TSDB_CODE_ACTION_IN_PROGRESS);
-      } else if (pConn->inType == 0) {
-        tTrace("%s cid:%d sid:%d id:%s, %s is already processed, tranId:%d pConn:%p", pServer->label, chann, sid,
-               pConn->meterId, taosMsg[pHeader->msgType], pConn->inTranId, pConn);
-        taosReSendRspToPeer(pConn);
+  if ( rpcIsReq(pHeader->msgType) ) {
+    code = rpcProcessReqHeader(pConn, pHeader);
   } else {
-        tTrace("%s cid:%d sid:%d id:%s, mismatched message %s and tranId pConn:%p", pServer->label, chann, sid,
-               pConn->meterId, taosMsg[pHeader->msgType], pConn);
-      }
-
-      // do not reply any message
-      code = TSDB_CODE_ALREADY_PROCESSED;
-      goto _exit;
+    code = rpcProcessRspHeader(pConn, pHeader);
   }
 
-    if (pConn->inType != 0) {
-      tTrace("%s cid:%d sid:%d id:%s, last session is not finished, inTranId:%d tranId:%d pConn:%p", pServer->label,
-             chann, sid, pConn->meterId, pConn->inTranId, pHeader->tranId, pConn);
-      code = TSDB_CODE_LAST_SESSION_NOT_FINISHED;
-      goto _exit;
-    }
-
-    pConn->inTranId = pHeader->tranId;
-    pConn->inType = pHeader->msgType;
-
-    if (sid == 0)  // send a response first
-      taosSendQuickRsp(pConn, (char)(pConn->inType + 1), TSDB_CODE_ACTION_IN_PROGRESS);
-
-  } else {
-    // response from taos
-    pConn->peerId = pHeader->sourceId;
-
-    if (pConn->outType == 0) {
-      code = TSDB_CODE_UNEXPECTED_RESPONSE;
-      goto _exit;
-    }
-
-    if (pHeader->tranId != pConn->outTranId) {
-      code = TSDB_CODE_INVALID_TRAN_ID;
-      goto _exit;
-    }
-
-    if (pHeader->msgType != pConn->outType + 1) {
-      code = TSDB_CODE_INVALID_RESPONSE_TYPE;
-      goto _exit;
-    }
-
-    if (*pHeader->content == TSDB_CODE_NOT_READY) {
-      code = TSDB_CODE_ALREADY_PROCESSED;
-      goto _exit;
-    }
-
-    taosTmrStopA(&pConn->pTimer);
-    pConn->retry = 0;
-
-    if (*pHeader->content == TSDB_CODE_ACTION_IN_PROGRESS || pHeader->tcp) {
-      if (pConn->tretry <= tsRpcMaxRetry) {
-        tTrace("%s cid:%d sid:%d id:%s, peer is still processing the transaction, pConn:%p", pServer->label, chann, sid,
-               pHeader->meterId, pConn);
-        pConn->tretry++;
-        taosTmrReset(taosProcessTaosTimer, tsRpcProgressTime, pConn, pChann->tmrCtrl, &pConn->pTimer);
-        code = TSDB_CODE_ALREADY_PROCESSED;
-        goto _exit;
-      } else {
-        // peer still in processing, give up
-        *pHeader->content = TSDB_CODE_TOO_SLOW;
-      }
-    }
-
-    pConn->tretry = 0;
-    if (pConn->rspReceived) {
-      code = TSDB_CODE_UNEXPECTED_RESPONSE;
-      goto _exit;
-    } else {
-      pConn->rspReceived = 1;
-    }
-  }
-
-_exit:
-  pthread_mutex_unlock(&pChann->mutex);
-
-  // if (reSend) taosReSendRspToPeer(pConn);
-
   return code;
 }
 
-int taosBuildErrorMsgToPeer(char *pMsg, int code, char *pReply) {
-  STaosHeader *pRecvHeader, *pReplyHeader;
-  char *       pContent;
+void rpcSendErrorMsgToPeer(char *pMsg, int32 code, uint_32 ip, uint_16 port, void *chandle) {
+  SRpcHeader  *pRecvHeader, *pReplyHeader;
+  char         msg[sizeof(SRpcHeader) + sizeof(SRpcDigest) + sizeof(STaosRsp)];
+  STaosRsp    *pRsp;
   uint32_t     timeStamp;
   int          msgLen;
 
-  pRecvHeader = (STaosHeader *)pMsg;
-  pReplyHeader = (STaosHeader *)pReply;
+  pRecvHeader = (SRpcHeader *)pMsg;
+  pReplyHeader = (SRpcHeader *)msg;
 
+  memset(msg, 0, sizeof(SRpcHeader));
   pReplyHeader->version = pRecvHeader->version;
   pReplyHeader->msgType = (char)(pRecvHeader->msgType + 1);
   pReplyHeader->tcp = 0;
@@ -1052,299 +780,328 @@ int taosBuildErrorMsgToPeer(char *pMsg, int code, char *pReply) {
   pReplyHeader->destId = pRecvHeader->sourceId;
   memcpy(pReplyHeader->meterId, pRecvHeader->meterId, tListLen(pReplyHeader->meterId));
 
-  pContent = (char *)pReplyHeader->content;
-  *pContent = (char)code;
-  pContent++;
+  pRsp = (STaosRsp *)pReplyHeader->content;
+  pRsp->code = htonl(code);
+  msgLen = sizeof(STaosRsp);
+  char *pContent = pRsp->more;
 
   if (code == TSDB_CODE_INVALID_TIME_STAMP) {
     // include a time stamp if client's time is not synchronized well
     timeStamp = taosGetTimestampSec();
     memcpy(pContent, &timeStamp, sizeof(timeStamp));
-    pContent += sizeof(timeStamp);
+    msgLen += sizeof(timeStamp);
   }
 
-  msgLen = (int)(pContent - pReply);
   pReplyHeader->msgLen = (int32_t)htonl((uint32_t)msgLen);
+  (*taosSendData[pRpc->type])(ip, port, pReply, msgLen, chandle);
 
-  return msgLen;
-}
-
-void taosReportDisconnection(SRpcChann *pChann, SRpcConn *pConn)
-{
-    SSchedMsg schedMsg;
-    schedMsg.fp = taosProcessSchedMsg;
-    schedMsg.msg = NULL;
-    schedMsg.ahandle = pConn->ahandle;
-    schedMsg.thandle = pConn;
-    taosScheduleTask(pChann->qhandle, &schedMsg);
+  return; 
 }
 
-void taosProcessIdleTimer(void *param, void *tmrId) {
+void rpcProcessIdleTimer(void *param, void *tmrId) {
   SRpcConn *pConn = (SRpcConn *)param;
   if (pConn->signature != param) {
     tError("idle timer pConn Signature:0x%x, pConn:0x%x not matched", pConn->signature, param);
     return;
   }
 
-  STaosRpc * pServer = pConn->pServer;
-  SRpcChann *pChann = pServer->channList + pConn->chann;
+  SRpcInfo * pRpc = pConn->pRpc;
   if (pConn->pIdleTimer != tmrId) {
-    tTrace("%s cid:%d sid:%d id:%s, idle timer:%p already processed pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, tmrId, pConn);
+    tTrace("%s pConn:%p, idle timer:%p already processed", pRpc->label, pConn, tmrId);
     return;
   }
 
-  int reportDisc = 0;
-
-  pthread_mutex_lock(&pChann->mutex);
-
-  tTrace("%s cid:%d sid:%d id:%s, close the connection since no activity pConn:%p", pServer->label, pConn->chann,
-         pConn->sid, pConn->meterId, pConn);
-  if (pConn->rspReceived == 0) {
-    pConn->rspReceived = 1;
-    reportDisc = 1;    
-  }
-
-  pthread_mutex_unlock(&pChann->mutex);
-
-  if (reportDisc) taosReportDisconnection(pChann, pConn);
+  tTrace("%s pConn:%p, close the connection since no activity", pRpc->label, pConn);
+  rpcCloseConn(pConn);
 }
 
-void *taosProcessDataFromPeer(char *data, int dataLen, uint32_t ip, uint16_t port, void *shandle, void *thandle,
+void *rpcProcessDataFromPeer(char *data, int dataLen, uint32_t ip, uint16_t port, void *shandle, void *thandle,
                               void *chandle) {
-  STaosHeader *pHeader;
+  SRpcHeader  *pHeader = (SRpcHeader *)data;
   uint8_t      code;
-  SRpcConn *   pConn = (SRpcConn *)thandle;
-  STaosRpc *   pServer = (STaosRpc *)shandle;
+  SRpcConn    *pConn = (SRpcConn *)thandle;
+  SRpcInfo    *pRpc = (SRpcInfo *)shandle;
   int          msgLen;
-  char         pReply[128];
-  SSchedMsg    schedMsg;
-  int          chann, sid;
-  SRpcChann *  pChann = NULL;
 
   tDump(data, dataLen);
 
-  if (ip == 0 && taosCloseConn[pServer->type]) {
-    // it means the connection is broken
-    if (pConn) {
-      pChann = pServer->channList + pConn->chann;
-      tTrace("%s cid:%d sid:%d id:%s, underlying link is gone pConn:%p", pServer->label, pConn->chann, pConn->sid,
-             pConn->meterId, pConn);
-      pConn->rspReceived = 1;
-      pConn->chandle = NULL;
-      taosReportDisconnection(pChann, pConn);
-    }
-    tfree(data);
+  if (ip == 0 && taosCloseConn[pRpc->type] && pConn) {
+    // it means the connection is broken, it only happens for TCP 
+    tTrace("%s pConn:%p, underlying link is gone%p", pRpc->label, pConn); 
+    pContext->terrno = TSDB_CODE_NETWORK_UNAVAIL;
+    taosTmrStart(taosProcessConnError, 0, pContext, pRpc->tmrCtrl); 
     return NULL;
   }
 
-  pHeader = (STaosHeader *)data;
-  msgLen = (int32_t)htonl((uint32_t)pHeader->msgLen);
-
-  code = (uint8_t)taosProcessMsgHeader(pHeader, &pConn, pServer, dataLen, ip, port, chandle);
+  pthread_mutex_lock(&pRpc->mutex);
+  code = rpcProcessHeader(pHeader, &pConn, pRpc, dataLen, ip, port, chandle);
+  pthread_mutex_unlock(&pRpc->mutex);
 
-  pHeader->destId = htonl(pHeader->destId);
-  chann = pHeader->destId >> pServer->bits;
-  sid = pHeader->destId & pServer->mask;
-
-  if (pConn && pServer->idleTime) {
-    SRpcChann *pChann = pServer->channList + pConn->chann;
-    taosTmrReset(taosProcessIdleTimer, pServer->idleTime, pConn, pChann->tmrCtrl, &pConn->pIdleTimer);
+  if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16)) {
+    tTrace("%s pConn:%p, %s received from 0x%x:%hu, parse code:%u len:%d source:0x%08x dest:0x%08x tranId:%d",
+        pRpc->label, pConn, taosMsg[pHeader->msgType], ip, port, code, 
+        dataLen, pHeader->sourceId, pHeader->destId, pHeader->tranId);
   }
 
-  if (code == TSDB_CODE_ALREADY_PROCESSED) {
-    tTrace("%s cid:%d sid:%d id:%s, %s wont be processed, source:0x%08x dest:0x%08x tranId:%d pConn:%p", pServer->label,
-           chann, sid, pHeader->meterId, taosMsg[pHeader->msgType], pHeader->sourceId, htonl(pHeader->destId),
-           pHeader->tranId, pConn);
-    free(data);
-    return pConn;
+  if (pConn && pRpc->idleTime) {
+    taosTmrReset(rpcProcessIdleTimer, pRpc->idleTime, pConn, pRpc->tmrCtrl, &pConn->pIdleTimer);
   }
 
-  if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16)) {
-    tTrace(
-        "%s cid:%d sid:%d id:%s, %s received from 0x%x:%hu, parse code:%u, first:%u len:%d source:0x%08x dest:0x%08x "
-        "tranId:%d pConn:%p",
-        pServer->label, chann, sid, pHeader->meterId, taosMsg[pHeader->msgType], ip, port, code, pHeader->content[0],
-        dataLen, pHeader->sourceId, htonl(pHeader->destId), pHeader->tranId, pConn);
+  if (code != TSDB_CODE_ALREADY_PROCESSED) {
+    if (code != 0) { // parsing error
+      if ( rpcIsReq(pHeader->msgType) ) {
+        taosSendErrorMsgToPeer(data, code, ip, port, chandle);
+        tTrace("%s pConn:%p, %s is sent with error code:%u", pRpc->label, pConn, taosMsg[pHeader->msgType+1], code);
+      } 
+    } else { // parsing OK
+      rpcProcessIncomingMsg(pConn, pHeader);
+    }
   }
 
-  if (code != 0) {
-    // parsing error
+  if ( code != 0 ) free (data);
+  return pConn;
+}
 
-    if (pHeader->msgType & 1U) {
-      memset(pReply, 0, sizeof(pReply));
+void taosProcessIncomingMsg(SRpcConn *pConn, SRpcHeader *pHeader) {
+  SRpcInfo *pRpc = pConn->pRpc;
+  int       msgLen = rpcContLenFromHeader(pHeader->msgLen);
 
-      msgLen = taosBuildErrorMsgToPeer(data, code, pReply);
-      (*taosSendData[pServer->type])(ip, port, pReply, msgLen, chandle);
-      tTrace("%s cid:%d sid:%d id:%s, %s is sent with error code:%u pConn:%p", pServer->label, chann, sid,
-             pHeader->meterId, taosMsg[pHeader->msgType + 1], code, pConn);
-    } else {
-      tTrace("%s cid:%d sid:%d id:%s, %s is received, parsing error:%u pConn:%p", pServer->label, chann, sid,
-             pHeader->meterId, taosMsg[pHeader->msgType], code, pConn);
-    }
+  pHeader = rpcDecompressRpcMsg(pHeader);
    
-    free(data);
+  if ( rpcIsReq(msgType) ) {
+    (*(pRpc->fp))(pHeader->msgType, pHeader->content, msgLen, pConn);
   } else {
-    // parsing OK
+    // it's a response
+    STaosRsp *pRsp = (STaosRsp *)msg;
+    int32_t code = htonl(pRsp->code);
 
-    // internal communication is based on TAOS protocol, a trick here to make it efficient
-    if (pHeader->spi) msgLen -= sizeof(STaosDigest);
-    msgLen -= (int)sizeof(STaosHeader);
-    pHeader->msgLen = msgLen + (int)sizeof(SIntMsg);
+    SRpcReqContext *pContext = pConn->pContext;
+    pConn->pContext = NULL;
 
-    if ((pHeader->msgType & 1U) == 0 && (pHeader->content[0] == TSDB_CODE_INVALID_VALUE)) {
-      schedMsg.msg = NULL;  // connection shall be closed
-    } else {
-      pHeader = taosDecompressRpcMsg(pHeader, &schedMsg, msgLen);
-    }
+    taosAddConnToIntoCache(pRpc->pCache, pConn, pConn->peerIp, pConn->peerPort, pConn->meterId);    
 
-    if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16U)) {
-      tTrace("%s cid:%d sid:%d id:%s, %s is put into queue, msgLen:%d pConn:%p pTimer:%p", pServer->label, chann, sid,
-             pHeader->meterId, taosMsg[pHeader->msgType], pHeader->msgLen, pConn, pConn->pTimer);
+    if (code == TSDB_CODE_NOT_MASTER) {
+      pContext->terrno = code;
+      taosTmrStart(taosProcessConnError, 0, pContext, pRpc->tmrCtrl); 
+    } else {
+      rpcFreeMsg(rpcGetMsgFromCont(pContext->cont)); // free the request msg
+      (*(pRpc->fp))(pHeader->msgType, pHeader->content, msgLen, pContext->ahandle);
     }
-
-    pChann = pServer->channList + pConn->chann;
-    schedMsg.fp = taosProcessSchedMsg;
-    schedMsg.ahandle = pConn->ahandle;
-    schedMsg.thandle = pConn;
-    taosScheduleTask(pChann->qhandle, &schedMsg);
   }
-
-  return pConn;
 }
 
-int taosSendMsgToPeerH(void *thandle, char *pCont, int contLen, void *ahandle) {
-  STaosHeader *pHeader;
-  SMsgNode *   pMsgNode;
-  char *       msg;
-  int          msgLen = 0;
-  SRpcConn *   pConn = (SRpcConn *)thandle;
-  STaosRpc *   pServer;
-  SRpcChann *  pChann;
-  uint8_t      msgType;
-
-  if (pConn == NULL) return -1;
-  if (pConn->signature != pConn) return -1;
+SRpcConn *rpcGetConnToServer(void *shandle, SRpcIpSet ipSet) {
+  SRpcInfo *pRpc = (SRpcInfo *)shandle;
 
-  pServer = pConn->pServer;
-  pChann = pServer->channList + pConn->chann;
-  pHeader = (STaosHeader *)(pCont - sizeof(STaosHeader));
-  pHeader->destIp = pConn->peerIp;
-  msg = (char *)pHeader;
+  SRpcConn *pConn = taosGetConnFromCache(pRpc->pCache, ipSet.ip[index], pRpc->peerPort, pRpc->meterId);
 
-  if ((pHeader->msgType & 1U) == 0 && pConn->localPort) pHeader->port = pConn->localPort;
+  if ( pConn == NULL ) {
+    SRpcConnInit connInit;
+    memset(&connInit, 0, sizeof(connInit));
+    connInit.sid = 0;
+    connInit.spi = pRpc->spi;
+    connInit.encrypt = pRpc->encrypt;
+    connInit.meterId = pRpc->user;
+    connInit.peerId = 0;
+    connInit.shandle = pRpc;
+    connInit.peerIp = ipstr;
+    connInit.peerPort = pRpc->peerPort;
+    pConn = rpcOpenConn(&connInit);
+  } 
 
-  contLen = taosCompressRpcMsg(pCont, contLen);
+  return pConn;
+}
 
-  msgLen = contLen + (int32_t)sizeof(STaosHeader);
+int taosAddAuthPart(SRpcConn *pConn, char *msg, int msgLen) {
+  SRpcHeader *pHeader = (SRpcHeader *)msg;
 
   if (pConn->spi) {
     // add auth part
     pHeader->spi = pConn->spi;
-    STaosDigest *pDigest = (STaosDigest *)(pCont + contLen);
+    SRpcDigest *pDigest = (SRpcDigest *)(msg + msgLen);
     pDigest->timeStamp = htonl(taosGetTimestampSec());
-    msgLen += sizeof(STaosDigest);
+    msgLen += sizeof(SRpcDigest);
     pHeader->msgLen = (int32_t)htonl((uint32_t)msgLen);
-    taosBuildAuthHeader((uint8_t *)pHeader, msgLen - TSDB_AUTH_LEN, pDigest->auth, pConn->secret);
+    rpcBuildAuthHeader((uint8_t *)pHeader, msgLen - TSDB_AUTH_LEN, pDigest->auth, pConn->secret);
   } else {
     pHeader->msgLen = (int32_t)htonl((uint32_t)msgLen);
   }
 
-  pthread_mutex_lock(&pChann->mutex);
-  msgType = pHeader->msgType;
+  return msgLen;
+}
 
-  if ((msgType & 1U) == 0) {
-    // response
-    pConn->inType = 0;
-    tfree(pConn->pRspMsg);
-    pConn->pRspMsg = msg;
-    pConn->rspMsgLen = msgLen;
+int rpcSendDataToPeer(SRpcConn *pConn, char *data, int dataLen) {
+  int          writtenLen = 0;
+  SRpcInfo    *pRpc = pConn->pRpc;
+  SRpcHeader  *pHeader = (SRpcHeader *)data;
+  int          code = 0;
 
-    if (pHeader->content[0] == TSDB_CODE_ACTION_IN_PROGRESS) pConn->inTranId--;
+  dataLen = taosAddAuthPart(pConn, data, dataLen);
 
+  if ( rpcIsReq(pHeader->msgType)) {
+    if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16))
+      tTrace("%s pConn:%p, %s is sent to %s:%hu, len:%d source:0x%08x dest:0x%08x tranId:%d",
+             pRpc->label, pConn, taosMsg[pHeader->msgType], pConn->peerIpstr,
+             pConn->peerPort, dataLen, pHeader->sourceId, pHeader->destId, pHeader->tranId);
   } else {
-    // request
-    pMsgNode = (SMsgNode *)(pCont - sizeof(STaosHeader) - sizeof(SMsgNode));
-    pMsgNode->msgLen = msgLen;
-    pMsgNode->next = NULL;
-    pMsgNode->ahandle = ahandle;
-
-    if (pConn->outType) {
-      if (pConn->pTail) {
-        pConn->pTail->next = pMsgNode;
-        pConn->pTail = pMsgNode;
-      } else {
-        pConn->pTail = pMsgNode;
-        pConn->pHead = pMsgNode;
+    if (pHeader->msgType < TSDB_MSG_TYPE_HEARTBEAT || (rpcDebugFlag & 16))
+      tTrace( "%s pConn:%p, %s is sent to %s:%hu, code:%u len:%d source:0x%08x dest:0x%08x tranId:%d",
+          pRpc->label, pConn, taosMsg[pHeader->msgType], pConn->peerIpstr, pConn->peerPort, 
+          (uint8_t)pHeader->content[0], dataLen, pHeader->sourceId, pHeader->destId, pHeader->tranId);
   }
 
-      tTrace("%s cid:%d sid:%d id:%s, msg:%s is put into queue pConn:%p", pServer->label, pConn->chann, pConn->sid,
-             pConn->meterId, taosMsg[msgType], pConn);
-      msgLen = 0;
+  writtenLen = (*taosSendData[pRpc->type])(pConn->peerIp, pConn->peerPort, (char *)pHeader, dataLen, pConn->chandle);
 
-    } else {
-      assert(pConn->pMsgNode == NULL);
-      if (pConn->pMsgNode) {
-        tError("%s cid:%d sid:%d id:%s, bug, there shall be no pengding req pConn:%p", pServer->label, pConn->chann,
-               pConn->sid, pConn->meterId, pConn);
+  if (writtenLen != dataLen) {
+    tError("%s pConn:%p, failed to send, dataLen:%d writtenLen:%d, reason:%s", pRpc->label, pConn, 
+           dataLen, writtenLen, strerror(errno));
+    code = -1; 
   }
  
+  tDump(data, dataLen);
+
+  return code;
+}
+
+void rpcSendReqToOneServer(SRpcConn *pConn, SRpcReqContext *pContext) {
+
+  char        *pHeader = rpcHeaderFromCont(pContext->pCont);
+  SRpcHeader  *msg = (char *)pHeader;
+  int          msgLen = rpcGetMsgLen(pContext->contLen);
+  char         msgType = pContext->msgType;
+
+  // set the message header  
+  pHeader->version = 1;
+  pHeader->msgType = msgType;
+  pHeader->tcp = 0;
+  pHeader->encrypt = 0;
+  pConn->tranId++;
+  if ( pConn->tranId == 0 ) pConn->tranId++;
+  pHeader->tranId = pConn->tranId;
+  pHeader->sourceId = pConn->ownId;
+  pHeader->destId = pConn->peerId;
+  pHeader->port = 0;
+  pHeader->uid = (uint32_t)((int64_t)pConn + (int64_t)getpid());
+  memcpy(pHeader->meterId, pConn->meterId, tListLen(pHeader->meterId));
+
+  // set the connection parameters
   pConn->outType = msgType;
   pConn->outTranId = pHeader->tranId;
   pConn->pMsgNode = pMsgNode;
-      pConn->rspReceived = 0;
-      if (pMsgNode->ahandle) pConn->ahandle = pMsgNode->ahandle;
-    }
-  }
+  pConn->pReqMsg = msg;
+  pConn->reqMsgLen = msgLen;
+  pConn->context = pContext;
 
-  if (msgLen) {
-    taosSendDataToPeer(pConn, (char *)pHeader, msgLen);
-    if (msgType & 1U) {
-      taosTmrReset(taosProcessTaosTimer, tsRpcTimer, pConn, pChann->tmrCtrl, &pConn->pTimer);
-    }
+  if ( rpcSendDataToPeer(pConn, msg, msgLen) < 0 ) {
+    taosReportError(pConn->pContext, terrno);
+  } else {
+    taosTmrReset(rpcProcessRetryTimer, tsRpcTimer, pConn, pRpc->tmrCtrl, &pConn->pTimer);
   }
+}
  
-  pthread_mutex_unlock(&pChann->mutex);
+void rpcSendRequest(void *shandle, SRpcIpSet ipSet, char type, char *pCont, int contLen, void *ahandle) {
+  SRpcConn       *pConn;
+  SRpcReqContext *pContext;
 
-  return contLen;
+  contLen = rpcCompressRpcMsg(pCont, contLen);
+  pContext = (SRpcReqContext *) (pCont-sizeof(SRpcHeader)-sizeof(SRpcReqContext));
+  pContext->ahandle = ahandle;
+  pContext->pRpc = (SRpcInfo *)shandle;
+  pContext->ipSet = ipSet;
+  pContext->contLen = contLen
+  pContext->pCont = pCont;
+  pContext->type = type;
+
+  pConn = rpcGetConnToServer(shandle, ipSet);
+  pContext->terrno = terrno;
+  if (pConn == NULL) taosTmrStart(taosProcessConnError, 0, pContext, pRpc->tmrCtrl); 
+
+  rpcSendReqToOneServer(pConn, pContext);
+
+  return;
 }
 
-int taosReSendRspToPeer(SRpcConn *pConn) {
-  STaosHeader *pHeader;
-  int          writtenLen;
-  STaosRpc *   pServer = pConn->pServer;
+void rpcSendResponse(SRpcConn *pConn, char *pCont, int contLen) {
+  int          msgLen = 0;
+  SRpcConn    *pConn;
+  SRpcHeader  *pHeader = rpcHeaderFromCont(pCont);
+  char        *msg = (char *)pHeader;
+
+  contLen = rpcCompressRpcMsg(pCont, contLen);
+  msgLen = rpcMsgLenFromCont(contLen);
+
+  pthread_mutex_lock(&pRpc->mutex);
 
-  if (pConn->pRspMsg == NULL || pConn->rspMsgLen <= 0) {
-    tError("%s cid:%d sid:%d id:%s, rsp is null", pServer->label, pConn->chann, pConn->sid, pConn->meterId);
-    return -1;
+  // set msg header
+  pHeader->version = 1;
+  pHeader->msgType = pConn->inType+1;
+  pHeader->spi = 0;
+  pHeader->tcp = 0;
+  pHeader->encrypt = 0;
+  pHeader->tranId = pConn->inTranId;
+  pHeader->sourceId = pConn->ownId;
+  pHeader->destId = pConn->peerId;
+  pHeader->uid = 0;
+  memcpy(pHeader->meterId, pConn->meterId, tListLen(pHeader->meterId));
+
+  // set pConn parameters
+  pConn->inType = 0;
+  rpcFreeMsg(pConn->pRspMsg);
+  pConn->pRspMsg = msg;
+  pConn->rspMsgLen = msgLen;
+
+  if (pHeader->content[0] == TSDB_CODE_ACTION_IN_PROGRESS) pConn->inTranId--;
+
+  pthread_mutex_lock(&pRpc->mutex);
+
+  rpcSendDataToPeer(pConn, msg, msgLen);
+
+  return;
+}
+
+static void rpcResendRspToPeer(SRpcConn *pConn) {
+
+  if (pConn->pRspMsg == NULL || pConn->rspMsgLen <= 0 || pConn->rspMsgLen <= sizeof(SRpcHeader)) {
+    tError("%s pConn:%p, rsp is null", pRpc->label);
+    return;
   }
 
-  pHeader = (STaosHeader *)pConn->pRspMsg;
-  if (pHeader->msgLen <= sizeof(SIntMsg) + 1 || pHeader->msgType <= 0) {
-    tError("%s cid:%d sid:%d id:%s, rsp is null, rspLen:%d, msgType:%d", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, pHeader->msgLen, pHeader->msgType);
-    return -1;
+  SRpcHeader *pHeader = (SRpcHeader *)pConn->pRspMsg;
+  if (pHeader->msgType <= 0) {
+    tError("%s pConn:%p, msgType is messed up, rspLen:%d, msgType:%d", pRpc->label, pConn, pHeader->msgLen, pHeader->msgType);
+    return;
   }
 
-  writtenLen =
-      (*taosSendData[pServer->type])(pConn->peerIp, pConn->peerPort, pConn->pRspMsg, pConn->rspMsgLen, pConn->chandle);
+  rpcSendDataToPeer(pConn, pConn->pRspMsg, pConn->rspMsgLen);
+}
+
+static void rpcProcessConnError(void *param, void *id) {
+  SRpcReqContext *pContext = (SRpcContext *)param;
 
-  if (writtenLen != pConn->rspMsgLen) {
-    tError("%s cid:%d sid:%d id:%s, failed to re-send %s, reason:%s pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, taosMsg[(int)pHeader->msgType], strerror(errno), pConn);
+  if ( pContext->numOfRetry >= pContext->ipSet.numOfIps ) {
+    char *rsp = calloc(1, RPC_MSG_OVERHEAD + sizeof(STaosRsp));
+    if ( rsp ) {
+      STaosRsp *pRsp = (rsp+sizeof(SRpcHeader));
+      pRsp->code = pContext->terrno;
+      (*(pRpc->fp))(pContext->msgType+1, pRsp, sizeof(STaosRsp), pContext->ahandle);  
     } else {
-    tTrace("%s cid:%d sid:%d id:%s, msg:%s is re-sent to %s:%hu, len:%d pConn:%p", pServer->label, pConn->chann,
-           pConn->sid, pConn->meterId, taosMsg[(int)pHeader->msgType], pConn->peerIpstr, pConn->peerPort,
-           pConn->rspMsgLen, pConn);
+      tError("%s failed to malloc RSP", pRpc->label);
     }
+  } else {
+    // move to next IP 
+    pContext->ipSet.index++;
+    pContext->ipSet.index = pContext->ipSet.index % pContext->ipSet.numOfIps;
     
-  return 0;
+    pConn = rpcGetConnToServer(pContext->pRpc, pContext->ipSet);
+    pContext->terrno = terrno;
+    if (pConn == NULL) taosTmrStart(taosProcessConnError, 0, pContext, pRpc->tmrCtrl); 
+
+    taosSendReqToOneServer(pConn, pContext);
+  }
 }
 
-void taosProcessTaosTimer(void *param, void *tmrId) {
-  STaosHeader *pHeader = NULL;
-  SRpcConn *   pConn = (SRpcConn *)param;
-  int          msgLen;
+static void rpcProcessRetryTimer(void *param, void *tmrId) {
+  SRpcConn *pConn = (SRpcConn *)param;
   int       reportDisc = 0;
 
   if (pConn->signature != param) {
@@ -1352,124 +1109,43 @@ void taosProcessTaosTimer(void *param, void *tmrId) {
     return;
   }
 
-  STaosRpc * pServer = pConn->pServer;
-  SRpcChann *pChann = pServer->channList + pConn->chann;
+  SRpcInfo *pRpc = pConn->pRpc;
 
   if (pConn->pTimer != tmrId) {
-    tTrace("%s cid:%d sid:%d id:%s, timer:%p already processed pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, tmrId, pConn);
+    tTrace("%s pConn:%p, timer:%p already processed%", pRpc->label, pConn);
     return;
   }
 
-  pthread_mutex_lock(&pChann->mutex);
+  pthread_mutex_lock(&pRpc->mutex);
 
-  if (pConn->rspReceived) {
-    tTrace("%s cid:%d sid:%d id:%s, rsp just received, pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, pConn);
-  } else if (pConn->outType == 0) {
-    tTrace("%s cid:%d sid:%d id:%s, outtype is zero, pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, pConn);
+  if (pConn->outType == 0) {
+    tTrace("%s pConn:%p, outtype is zero", pRpc->label, pConn);
   } else {
-    tTrace("%s cid:%d sid:%d id:%s, expected %s is not received, pConn:%p", pServer->label, pConn->chann, pConn->sid,
-           pConn->meterId, taosMsg[(int)pConn->outType + 1], pConn);
+    tTrace("%s pConn:%p, expected %s is not received", pRpc->label, pConn, taosMsg[(int)pConn->outType + 1]);
     pConn->pTimer = NULL;
     pConn->retry++;
 
     if (pConn->retry < 4) {
-      tTrace("%s cid:%d sid:%d id:%s, re-send msg:%s to %s:%hu pConn:%p", pServer->label, pConn->chann, pConn->sid,
-             pConn->meterId, taosMsg[pConn->outType], pConn->peerIpstr, pConn->peerPort, pConn);
-      if (pConn->pMsgNode && pConn->pMsgNode->msgLen > 0) {
-        pHeader = (STaosHeader *)((char *)pConn->pMsgNode + sizeof(SMsgNode));
-        pHeader->destId = pConn->peerId;
-        msgLen = pConn->pMsgNode->msgLen;
-        if (pConn->spi) {
-          STaosDigest *pDigest = (STaosDigest *)(((char *)pHeader) + pConn->pMsgNode->msgLen - sizeof(STaosDigest));
-          pDigest->timeStamp = htonl(taosGetTimestampSec());
-          taosBuildAuthHeader((uint8_t *)pHeader, pConn->pMsgNode->msgLen - TSDB_AUTH_LEN, pDigest->auth,
-                              pConn->secret);
-        }
+      tTrace("%s pConn:%p, re-send msg:%s to %s:%hu", pRpc->label,
+             taosMsg[pConn->outType], pConn->peerIpstr, pConn->peerPort);
+      if (pConn->pReqMsg && pConn->pReqMsgLen > 0) {
+        rpcSendDataToPeer(pConn, pReqMsg, pReqMsgLen);      
       }
     } else {
       // close the connection
-      tTrace("%s cid:%d sid:%d id:%s, failed to send msg:%s to %s:%hu pConn:%p", pServer->label, pConn->chann,
-             pConn->sid, pConn->meterId, taosMsg[pConn->outType], pConn->peerIpstr, pConn->peerPort, pConn);
-      if (pConn->rspReceived == 0) {
-        pConn->rspReceived = 1;
+      tTrace("%s pConn:%p, failed to send msg:%s to %s:%hu", pRpc->label, pConn,
+              taosMsg[pConn->outType], pConn->peerIpstr, pConn->peerPort, pConn);
       reportDisc = 1;
     }
   }
-  }
-
-  if (pHeader) {
-    (*taosSendData[pServer->type])(pConn->peerIp, pConn->peerPort, (char *)pHeader, msgLen, pConn->chandle);
-    taosTmrReset(taosProcessTaosTimer, tsRpcTimer<<pConn->retry, pConn, pChann->tmrCtrl, &pConn->pTimer);
-  }
-
-  pthread_mutex_unlock(&pChann->mutex);
-
-  if (reportDisc) taosReportDisconnection(pChann, pConn);
-}
-
-void taosGetRpcConnInfo(void *thandle, uint32_t *peerId, uint32_t *peerIp, uint16_t *peerPort, int *cid, int *sid) {
-  SRpcConn *pConn = (SRpcConn *)thandle;
-
-  *peerId = pConn->peerId;
-  *peerIp = pConn->peerIp;
-  *peerPort = pConn->peerPort;
-
-  *cid = pConn->chann;
-  *sid = pConn->sid;
-}
-
-int taosGetOutType(void *thandle) {
-  SRpcConn *pConn = (SRpcConn *)thandle;
-  if (pConn == NULL) return -1;
-
-  return pConn->outType;
-}
 
-void taosProcessSchedMsg(SSchedMsg *pMsg) {
-  SIntMsg * pHeader = (SIntMsg *)pMsg->msg;
-  SRpcConn *pConn = (SRpcConn *)pMsg->thandle;
-  if (pConn == NULL || pConn->signature != pMsg->thandle || pConn->pServer == NULL) return;
-  STaosRpc *pRpc = pConn->pServer;
-
-  void *ahandle = (*(pRpc->fp))(pMsg->msg, pMsg->ahandle, pMsg->thandle);
-
-  if (ahandle == NULL || pMsg->msg == NULL) {
-    taosCloseRpcConn(pConn);
-  } else {
-    pConn->ahandle = ahandle;
-    if (pHeader && ((pHeader->msgType & 1) == 0)) taosProcessResponse(pConn);
-  }
-
-  if (pMsg->msg) free(pMsg->msg - sizeof(STaosHeader) + sizeof(SIntMsg));
-}
-
-void taosStopRpcConn(void *thandle) {
-  SRpcConn * pConn = (SRpcConn *)thandle;
-  STaosRpc * pServer = pConn->pServer;
-  SRpcChann *pChann = pServer->channList + pConn->chann;
-
-  tTrace("%s cid:%d sid:%d id:%s, stop the connection pConn:%p", pServer->label, pConn->chann, pConn->sid,
-         pConn->meterId, pConn);
-
-  int reportDisc = 0;
-  pthread_mutex_lock(&pChann->mutex);
-
-  if (pConn->outType) {
-    pConn->rspReceived = 1;
-    reportDisc = 1;
-    pthread_mutex_unlock(&pChann->mutex);
-  } else {
-    pthread_mutex_unlock(&pChann->mutex);
-    taosCloseRpcConn(pConn);
-  }
+  pthread_mutex_unlock(&pRpc->mutex);
 
-  if (reportDisc) taosReportDisconnection(pChann, pConn);
+  pConn->terrno = TSDB_CODE_NETWORK_UNAVAIL;
+  if (reportDisc) taosProcessConnError(pConn->pContext, NULL);
 }
 
-int taosAuthenticateMsg(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey) {
+static int rpcAuthenticateMsg(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey) {
   MD5_CTX context;
   int     ret = -1;
 
@@ -1484,7 +1160,7 @@ int taosAuthenticateMsg(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey
   return ret;
 }
 
-int taosBuildAuthHeader(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey) {
+static int rpcBuildAuthHeader(uint8_t *pMsg, int msgLen, uint8_t *pAuth, uint8_t *pKey) {
   MD5_CTX context;
 
   MD5Init(&context);

src/util/inc/tbuffer.h

+/*
+ * Copyright (c) 2020 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <setjmp.h>
+
+#ifndef TDENGINE_TBUFFER_H
+#define TDENGINE_TBUFFER_H
+
+
+/*
+SBuffer can be used to read or write a buffer, but cannot be used for both
+read & write at a same time. Below is an example:
+
+int main(int argc, char** argv) {
+  //--------------------- write ------------------------
+  SBuffer wbuf;
+  int32_t code = tbufBeginWrite(&wbuf);
+  if (code != 0) {
+    // handle errors
+    return 0;
+  }
+
+  // reserve 1024 bytes for the buffer to improve performance
+  tbufEnsureCapacity(&wbuf, 1024);
+
+  // write 5 integers to the buffer
+  for (int i = 0; i < 5; i++) {
+    tbufWriteInt32(&wbuf, i);
+  }
+
+  // write a string to the buffer
+  tbufWriteString(&wbuf, "this is a string.\n");
+
+  // acquire the result and close the write buffer
+  size_t size = tbufTell(&wbuf);
+  char*  data = tbufGetData(&wbuf, true);
+  tbufClose(&wbuf, true);
+
+
+  //------------------------ read -----------------------
+  SBuffer rbuf;
+  code = tbufBeginRead(&rbuf, data, size);
+  if (code != 0) {
+    printf("you will see this message after print out 5 integers and a string.\n");
+    tbufClose(&rbuf, false);
+    return 0;
+  }
+
+  // read & print out 5 integers
+  for (int i = 0; i < 5; i++) {
+    printf("%d\n", tbufReadInt32(&rbuf));
+  }
+
+  // read & print out a string
+  printf(tbufReadString(&rbuf, NULL));
+
+  // try read another integer, this result in an error as there no this integer
+  tbufReadInt32(&rbuf);
+
+  printf("you should not see this message.\n");
+  tbufClose(&rbuf, false);
+
+  return 0;
+}
+*/
+typedef struct {
+  jmp_buf jb;
+  char* data;
+  size_t pos;
+  size_t size;
+} SBuffer;
+
+
+// common functions can be used in both read & write
+#define tbufThrowError(buf, code) longjmp((buf)->jb, (code))
+size_t tbufTell(SBuffer* buf);
+size_t tbufSeekTo(SBuffer* buf, size_t pos);
+size_t tbufSkip(SBuffer* buf, size_t size);
+void tbufClose(SBuffer* buf, bool keepData);
+
+
+// basic read functions
+#define tbufBeginRead(buf, data, len) (((buf)->data = (char*)data), ((buf)->pos = 0), ((buf)->size = ((data) == NULL) ? 0 : (len)), setjmp((buf)->jb))
+char* tbufRead(SBuffer* buf, size_t size);
+void tbufReadToBuffer(SBuffer* buf, void* dst, size_t size);
+const char* tbufReadString(SBuffer* buf, size_t* len);
+size_t tbufReadToString(SBuffer* buf, char* dst, size_t size);
+
+
+// basic write functions
+#define tbufBeginWrite(buf) ((buf)->data = NULL, ((buf)->pos = 0), ((buf)->size = 0), setjmp((buf)->jb))
+void tbufEnsureCapacity(SBuffer* buf, size_t size);
+char* tbufGetData(SBuffer* buf, bool takeOver);
+void tbufWrite(SBuffer* buf, const void* data, size_t size);
+void tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size);
+void tbufWriteStringLen(SBuffer* buf, const char* str, size_t len);
+void tbufWriteString(SBuffer* buf, const char* str);
+
+
+// read & write function for primitive types
+#ifndef TBUFFER_DEFINE_FUNCTION
+#define TBUFFER_DEFINE_FUNCTION(type, name) \
+  type tbufRead##name(SBuffer* buf); \
+  void tbufWrite##name(SBuffer* buf, type data); \
+  void tbufWrite##name##At(SBuffer* buf, size_t pos, type data);
+#endif
+
+TBUFFER_DEFINE_FUNCTION( bool, Bool )
+TBUFFER_DEFINE_FUNCTION( char, Char )
+TBUFFER_DEFINE_FUNCTION( int8_t, Int8 )
+TBUFFER_DEFINE_FUNCTION( uint8_t, Unt8 )
+TBUFFER_DEFINE_FUNCTION( int16_t, Int16 )
+TBUFFER_DEFINE_FUNCTION( uint16_t, Uint16 )
+TBUFFER_DEFINE_FUNCTION( int32_t, Int32 )
+TBUFFER_DEFINE_FUNCTION( uint32_t, Uint32 )
+TBUFFER_DEFINE_FUNCTION( int64_t, Int64 )
+TBUFFER_DEFINE_FUNCTION( uint64_t, Uint64 )
+TBUFFER_DEFINE_FUNCTION( float, Float )
+TBUFFER_DEFINE_FUNCTION( double, Double )
+
+#endif
\ No newline at end of file

src/util/src/tbuffer.c

+/*
+ * Copyright (c) 2020 TAOS Data, Inc. <jhtao@taosdata.com>
+ *
+ * This program is free software: you can use, redistribute, and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3
+ * or later ("AGPL"), as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <memory.h>
+#include <assert.h>
+
+#define TBUFFER_DEFINE_FUNCTION(type, name) \
+  type tbufRead##name(SBuffer* buf) {            \
+    type ret;                                    \
+    tbufReadToBuffer(buf, &ret, sizeof(type));   \
+    return ret;                                  \
+  }\
+  void tbufWrite##name(SBuffer* buf, type data) {\
+    tbufWrite(buf, &data, sizeof(data));\
+  }\
+  void tbufWrite##name##At(SBuffer* buf, size_t pos, type data) {\
+    tbufWriteAt(buf, pos, &data, sizeof(data));\
+  }
+
+#include "../inc/tbuffer.h"
+
+
+////////////////////////////////////////////////////////////////////////////////
+// common functions
+
+size_t tbufTell(SBuffer* buf) {
+  return buf->pos;
+}
+
+size_t tbufSeekTo(SBuffer* buf, size_t pos) {
+  if (pos > buf->size) {
+    // TODO: update error code, other tbufThrowError need to be changed too
+    tbufThrowError(buf, 1);
+  }
+  size_t old = buf->pos;
+  buf->pos = pos;
+  return old;
+}
+
+size_t tbufSkip(SBuffer* buf, size_t size) {
+  return tbufSeekTo(buf, buf->pos + size);
+}
+
+void tbufClose(SBuffer* buf, bool keepData) {
+  if (!keepData) {
+    free(buf->data);
+  }
+  buf->data = NULL;
+  buf->pos = 0;
+  buf->size = 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// read functions
+
+char* tbufRead(SBuffer* buf, size_t size) {
+  char* ret = buf->data + buf->pos;
+  tbufSkip(buf, size);
+  return ret;
+}
+
+void tbufReadToBuffer(SBuffer* buf, void* dst, size_t size) {
+  assert(dst != NULL);
+  // always using memcpy, leave optimization to compiler
+  memcpy(dst, tbufRead(buf, size), size);
+}
+
+const char* tbufReadString(SBuffer* buf, size_t* len) {
+  uint16_t l = tbufReadUint16(buf);
+  char*    ret = buf->data + buf->pos;
+  tbufSkip(buf, l + 1);
+  ret[l] = 0;  // ensure the string end with '\0'
+  if (len != NULL) {
+    *len = l;
+  }
+  return ret;
+}
+
+size_t tbufReadToString(SBuffer* buf, char* dst, size_t size) {
+  assert(dst != NULL);
+  size_t      len;
+  const char* str = tbufReadString(buf, &len);
+  if (len >= size) {
+    len = size - 1;
+  }
+  memcpy(dst, str, len);
+  dst[len] = 0;
+  return len;
+}
+
+
+////////////////////////////////////////////////////////////////////////////////
+// write functions
+
+void tbufEnsureCapacity(SBuffer* buf, size_t size) {
+  size += buf->pos;
+  if (size > buf->size) {
+    size_t nsize = size + buf->size;
+    char* data = realloc(buf->data, nsize);
+    if (data == NULL) {
+      tbufThrowError(buf, 2);
+    }
+    buf->data = data;
+    buf->size = nsize;
+  }
+}
+
+char* tbufGetData(SBuffer* buf, bool takeOver) {
+		char* ret = buf->data;
+		if (takeOver) {
+      buf->pos = 0;
+      buf->size = 0;
+			buf->data = NULL;
+    }
+		return ret;
+}
+
+void tbufEndWrite(SBuffer* buf) {
+    free(buf->data);
+    buf->data = NULL;
+    buf->pos = 0;
+    buf->size = 0;
+}
+
+void tbufWrite(SBuffer* buf, const void* data, size_t size) {
+  assert(data != NULL);
+  tbufEnsureCapacity(buf, size);
+  memcpy(buf->data + buf->pos, data, size);
+  buf->pos += size;
+}
+
+void tbufWriteAt(SBuffer* buf, size_t pos, const void* data, size_t size) {
+  assert(data != NULL);
+  // this function can only be called to fill the gap on previous writes,
+  // so 'pos + size <= buf->pos' must be true
+  assert(pos + size <= buf->pos);
+  memcpy(buf->data + pos, data, size);
+}
+
+void tbufWriteStringLen(SBuffer* buf, const char* str, size_t len) {
+  // maximum string length is 65535, if longer string is required
+  // this function and the corresponding read function need to be
+  // revised.
+  assert(len <= 0xffff);
+  tbufWriteUint16(buf, (uint16_t)len);
+  tbufWrite(buf, str, len + 1);
+}
+
+void tbufWriteString(SBuffer* buf, const char* str) {
+  tbufWriteStringLen(buf, str, strlen(str));
+}

src/vnode/CMakeLists.txt

-CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
-PROJECT(TDengine)
+cmake_minimum_required(VERSION 2.8)
 
-ADD_SUBDIRECTORY(detail)
+project(tsdb)
\ No newline at end of file
+
+add_subdirectory(common)
+
+add_subdirectory(tsdb)
\ No newline at end of file

src/vnode/common/CMakeLists.txt

+aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/src SOURCE_LIST)
+
+list(REMOVE_ITEM SOURCE_LIST ${CMAKE_CURRENT_SOURCE_DIR}/src/vnodePeer.c)
+
+message(STATUS "Common source file ${SOURCE_LIST}")
+
+add_library(common ${SOURCE_LIST})
+target_include_directories(common PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/inc")

src/vnode/common/src/schema.c

@@ -51,7 +51,7 @@ SISchema tdConvertSchemaToInline(SSchema *pSchema) {
   char *pName = TD_ISCHEMA_COL_NAMES(pISchema);
   for (int32_t i = 0; i < totalCols; i++) {
     SColumn *pCol = TD_SCHEMA_COLUMN_AT(TD_ISCHEMA_SCHEMA(pISchema), i);
-    char *   colName = TD_COLUMN_NAME(TD_SCHEMA_COLUMN_AT(pSchema, i), i);
+    char *   colName = TD_COLUMN_NAME(TD_SCHEMA_COLUMN_AT(pSchema, i));
 
     TD_COLUMN_NAME(pCol) = pName;
 

src/vnode/tsdb/CMakeLists.txt

+aux_source_directory(${CMAKE_CURRENT_SOURCE_DIR}/src SOURCE_LIST)
+
+message(STATUS "tsdb source files: ${SOURCE_LIST}")
+
+add_library(tsdb STATIC ${SOURCE_LIST})
+
+target_link_libraries(tsdb common)
+
+target_include_directories(tsdb PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/inc")
\ No newline at end of file

src/vnode/tsdb/inc/tsdb.h

@@ -8,7 +8,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include "cache.h"
+// #include "cache.h"
 #include "schema.h"
 
 #define TSDB_VERSION_MAJOR 1
@@ -18,6 +18,21 @@ typedef void    tsdb_repo_t;  // use void to hide implementation details from ou
 typedef int32_t table_id_t;   // table ID type in this repository
 typedef int16_t tsdb_id_t;    // TSDB repository ID
 
+// Submit message
+typedef struct {
+  int32_t numOfTables;
+  char    data[];
+} SSubmitMsg;
+
+// Submit message for one table
+typedef struct {
+  table_id_t tableId;       // table ID to insert
+  int32_t    sversion;      // data schema version
+  int32_t    numOfRows;     // number of rows data
+  int64_t    uid;           // table UID to insert
+  char       data[];
+} SSubmitBlock;
+
 // Retention policy.
 typedef struct {
   // TODO: Need a more fancy description
@@ -54,7 +69,7 @@ typedef struct {
   SDataShardPolicy dataShardPolicy;
   SBlockRowsPolicy blockRowsPolicy;
   SRetentionPolicy retentionPlicy;  // retention configuration
-  SCachePool *     cachePool;       // the cache pool the repository to use
+  void *           cachePool;       // the cache pool the repository to use
 } STSDBCfg;
 
 // the TSDB repository info
@@ -205,6 +220,9 @@ typedef struct STimeWindow {
   int64_t ekey;
 } STimeWindow;
 
+typedef struct {
+} SColumnFilterInfo;
+
 // query condition to build vnode iterator
 typedef struct STSDBQueryCond {
   STimeWindow       twindow;
@@ -237,6 +255,10 @@ typedef struct STableIDList {
   int32_t   num;
 } STableIDList;
 
+typedef struct {
+
+} SFields;
+
 /**
  * Get the data block iterator, starting from position according to the query condition
  * @param pRepo  the TSDB repository to query on

src/vnode/tsdb/inc/tsdbCache.h

@@ -3,7 +3,7 @@
 
 #include <stdint.h>
 
-#include "cache.h"
+// #include "cache.h"
 
 #define TSDB_DEFAULT_CACHE_BLOCK_SIZE 16*1024*1024 /* 16M */
 
@@ -13,11 +13,11 @@ typedef struct {
   int32_t numOfRows // numOfRows
 } STableCacheInfo;
 
-typedef struct {
-  char *pData;
-  STableCacheInfo *pTableInfo;
-  SCacheBlock *prev;
-  SCacheBlock *next;
+typedef struct _tsdb_cache_block {
+  char *                    pData;
+  STableCacheInfo *         pTableInfo;
+  struct _tsdb_cache_block *prev;
+  struct _tsdb_cache_block *next;
 } STSDBCacheBlock;
 
 // Use a doublely linked list to implement this
@@ -28,7 +28,6 @@ typedef struct STSDBCache {
   void *           current;
 } SCacheHandle;
 
-
 // ---- Operation on STSDBCacheBlock
 #define TSDB_CACHE_BLOCK_DATA(pBlock) ((pBlock)->pData)
 #define TSDB_CACHE_AVAIL_SPACE(pBlock) ((char *)((pBlock)->pTableInfo) - ((pBlock)->pData))

src/vnode/tsdb/inc/tsdbFile.h

 #if !defined(_TD_TSDB_FILE_H_)
 #define _TD_TSDB_FILE_H_
 
-#include "tstring.h"
+#include <stdint.h>
+// #include "tstring.h"
 
 typedef int32_t file_id_t;
 
@@ -24,7 +25,7 @@ typedef struct {
 } SFileInfo;
 
 typedef struct {
-  tstring_t fname;
+  char *    fname;
   SFileInfo fInfo;
 } SFILE;
 

src/vnode/tsdb/inc/tsdbMeta.h

@@ -4,7 +4,7 @@
 
 #include <pthread.h>
 
-#include "taosdef.h"
+// #include "taosdef.h"
 
 // Initially, there are 4 tables
 #define TSDB_INIT_NUMBER_OF_SUPER_TABLE 4
@@ -30,7 +30,7 @@ typedef struct STable {
   // For TSDB_SUPER_TABLE, it is the schema including tags
   // For TSDB_NTABLE, it is only the schema, not including tags
   // For TSDB_STABLE, it is NULL
-  SVSchema *pSchema;
+  SSchema *pSchema;
 
   // Tag value for this table
   // For TSDB_SUPER_TABLE and TSDB_NTABLE, it is NULL
@@ -75,7 +75,7 @@ typedef struct {
 #define TSDB_TABLE_CACHE_DATA(pTable) ((pTable)->content.pData)
 #define TSDB_SUPER_TABLE_INDEX(pTable) ((pTable)->content.pIndex)
 
-SVSchema *tsdbGetTableSchema(STable *pTable);
+SSchema *tsdbGetTableSchema(STable *pTable);
 
 // ---- Operation on SMetaHandle
 #define TSDB_NUM_OF_TABLES(pHandle) ((pHandle)->numOfTables)

src/vnode/tsdb/src/tsdb.c

@@ -2,14 +2,15 @@
 #include <stdint.h>
 #include <stdlib.h>
 
-#include "taosdef.h"
+// #include "taosdef.h"
 // #include "disk.h"
+#include "tsdb.h"
 #include "tsdbCache.h"
 #include "tsdbMeta.h"
 
 typedef struct STSDBRepo {
   // TSDB configuration
-  STSDBcfg *pCfg;
+  STSDBCfg *pCfg;
 
   // The meter meta handle of this TSDB repository
   SMetaHandle *pMetaHandle;
@@ -18,12 +19,12 @@ typedef struct STSDBRepo {
   SCacheHandle *pCacheHandle;
 
   // Disk tier handle for multi-tier storage
-  SDiskTier *pDiskTier;
+  void *pDiskTier;
 
   // File Store
   void *pFileStore;
 
-  pthread_mutext_t tsdbMutex;
+  pthread_mutex_t tsdbMutex;
 
 } STSDBRepo;
 

src/vnode/tsdb/src/tsdbFileStore.c

 #include "tsdbFile.h"
 
 char *tsdbGetFileName(char *dirName, char *fname, TSDB_FILE_TYPE type){
-    char *suffix = tsdbFileSuffix[type];
+    // char *suffix = tsdbFileSuffix[type];
     // TODO 
 }
\ No newline at end of file

src/vnode/tsdb/src/tsdbMeta.c

 #include <stdlib.h>
 
-#include "taosdef.h"
+// #include "taosdef.h"
+#include "tsdb.h"
 #include "tsdbMeta.h"
 
 SMetaHandle *tsdbCreateMetaHandle(int32_t numOfTables) {
@@ -11,7 +12,7 @@ SMetaHandle *tsdbCreateMetaHandle(int32_t numOfTables) {
 
   pMetahandle->numOfTables = 0;
   pMetahandle->numOfSuperTables = 0;
-  pMetahandle->pTables = calloc(sizeof(STable *) * numOfTables);
+  pMetahandle->pTables = calloc(sizeof(STable *), numOfTables);
   if (pMetahandle->pTables == NULL) {
     free(pMetahandle);
     return NULL;