[feature][TD-10557]add raft interface

src/raft/inc/raft.h

-/*
- * Copyright (c) 2019 TAOS Data, Inc. <cli@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 TD_RAFT_H
-#define TD_RAFT_H
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#include <stdio.h>
-#include "taosdef.h"
-
-typedef unsigned int RaftId;
-typedef unsigned int RaftGroupId;
-
-// buffer holding data
-typedef struct RaftBuffer {
-  void* data;
-  size_t len;
-} RaftBuffer;
-
-// a single server information in a cluster
-typedef struct RaftServer {
-  RaftId    id;
-  char      fqdn[TSDB_FQDN_LEN];
-  uint16_t  port;
-} RaftServer;
-
-// all servers in a cluster
-typedef struct RaftConfiguration {
-  RaftServer *servers;
-  int nServer;
-} RaftConfiguration;
-
-// raft lib module
-struct Raft;
-typedef struct Raft Raft;
-
-struct RaftNode;
-typedef struct RaftNode RaftNode;
-
-// raft state machine
-struct RaftFSM;
-typedef struct RaftFSM {
-  // statemachine user data
-  void *data;
-
-  // apply buffer data, bufs will be free by raft module
-  int (*apply)(struct RaftFSM *fsm, const RaftBuffer *bufs[], int nBufs);
-
-  // fsm return snapshot in ppBuf, bufs will be free by raft module
-  // TODO: getSnapshot SHOULD be async?
-  int (*getSnapshot)(struct RaftFSM *fsm, RaftBuffer **ppBuf);
-
-  // fsm restore with pBuf data
-  int (*restore)(struct RaftFSM *fsm, RaftBuffer *pBuf);
-
-  // fsm send data in buf to server,buf will be free by raft module
-  int (*send)(struct RaftFSM* fsm, const RaftServer* server, const RaftBuffer *buf);
-} RaftFSM;
-
-typedef struct RaftNodeOptions {
-  // user define state machine
-  RaftFSM* pFSM;
-
-  // election timeout(in ms)
-  // by default: 150
-  int electionTimeoutMS;
-
-  // heart timeout(in ms)
-  // by default: 50
-  int heartbeatTimeoutMS;
-
-  // install snapshot timeout(in ms)
-  int installSnapshotTimeoutMS;
-
-  /** 
-   * number of log entries before starting a new snapshot. 
-   * by default: 1024
-   */
-  int snapshotThreshold;
-
-  /**
-   * Number of log entries to keep in the log after a snapshot has
-   * been taken. 
-   * by default: 128.
-   */
-  int snapshotTrailing;
-
-  /**
-   * Enable or disable pre-vote support.
-   * by default: false
-   */
-  bool preVote;
-
-} RaftNodeOptions;
-
-int RaftCreate(Raft** ppRaft);
-
-int RaftDestroy(Raft* pRaft);
-
-// start a raft node with options and cluster configuration
-int RaftStart(Raft* pRaft, 
-              RaftId selfId,
-              RaftGroupId selfGroupId,
-              const RaftNodeOptions* options,
-              const RaftConfiguration* cluster
-              RaftNode **ppNode);
-
-// stop a raft node
-int RaftStop(RaftNode* pNode);
-
-// client apply a cmd in buf
-typedef void (*RaftApplyFp)(const RaftBuffer *pBuf, int result);
-
-int RaftApply(RaftNode *pNode,
-              const RaftBuffer *pBuf,
-              RaftApplyFp applyCb);
-
-// recv data from other servers in cluster,buf will be free in raft
-int RaftRecv(RaftNode *pNode, const RaftBuffer* pBuf);
-
-// change cluster servers API
-typedef void (*RaftChangeFp)(const RaftServer* pServer, int result);
-
-int RaftAddServer(RaftNode *pNode,
-                  const RaftServer* pServer,
-                  RaftChangeFp changeCb);
-
-int RaftRemoveServer(RaftNode *pNode, 
-                    const RaftServer* pServer,
-                    RaftChangeFp changeCb);
-
-// transfer leader to id
-typedef void (*RaftTransferFp)(RaftId id, int result);
-int RaftTransfer(RaftNode *pNode,
-                 RaftId id,
-                 RaftTransferFp transferCb);
-
-#ifdef __cplusplus
-}
-#endif
-
-#endif  /* TD_RAFT_H */ 
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