[TD-116] add vnodeAccquire vnode

src/dnode/src/dnodeRead.c

@@ -82,16 +82,17 @@ void dnodeRead(SRpcMsg *pMsg) {
 
   dTrace("dnode %s msg incoming, thandle:%p", taosMsg[pMsg->msgType], pMsg->handle);
 
-  if (pMsg->msgType == TSDB_MSG_TYPE_RETRIEVE) {
-    queuedMsgNum = 0;
-  }
-
   while (leftLen > 0) {
     SMsgHead *pHead = (SMsgHead *) pCont;
     pHead->vgId    = htonl(pHead->vgId);
     pHead->contLen = htonl(pHead->contLen);
 
-    pVnode = vnodeGetVnode(pHead->vgId);
+    if (pMsg->msgType == TSDB_MSG_TYPE_RETRIEVE) {
+      pVnode = vnodeGetVnode(pHead->vgId);
+    } else {
+      pVnode = vnodeAccquireVnode(pHead->vgId);
+    }
+
     if (pVnode == NULL) {
       leftLen -= pHead->contLen;
       pCont -= pHead->contLen;
@@ -261,7 +262,6 @@ static void dnodeProcessQueryMsg(void *pVnode, SReadMsg *pMsg) {
   
     rpcSendResponse(&rpcRsp);
     dTrace("dnode query msg disposed, thandle:%p", pMsg->rpcMsg.handle);
-    vnodeRelease(pVnode);
   } else {
     pQInfo = pMsg->pCont;
   }

src/inc/vnode.h

@@ -31,7 +31,8 @@ int32_t vnodeOpen(int32_t vgId, char *rootDir);
 int32_t vnodeClose(int32_t vgId);
 
 void    vnodeRelease(void *pVnode);
-void*   vnodeGetVnode(int32_t vgId);
+void*   vnodeAccquireVnode(int32_t vgId); // add refcount 
+void*   vnodeGetVnode(int32_t vgId);      // keep refcount unchanged
 
 void*   vnodeGetRqueue(void *);
 void*   vnodeGetWqueue(int32_t vgId);

src/vnode/main/src/vnodeMain.c

@@ -219,6 +219,13 @@ void *vnodeGetVnode(int32_t vgId) {
     return NULL;
   }
 
+  return pVnode;
+}
+
+void *vnodeAccquireVnode(int32_t vgId) {
+  SVnodeObj *pVnode = vnodeGetVnode(vgId);
+  if (pVnode == NULL) return pVnode;
+
   atomic_add_fetch_32(&pVnode->refCount, 1);
   dTrace("pVnode:%p vgId:%d, get vnode, refCount:%d", pVnode, pVnode->vgId, pVnode->refCount);
 
@@ -230,7 +237,7 @@ void *vnodeGetRqueue(void *pVnode) {
 }
 
 void *vnodeGetWqueue(int32_t vgId) {
-  SVnodeObj *pVnode = vnodeGetVnode(vgId);
+  SVnodeObj *pVnode = vnodeAccquireVnode(vgId);
   if (pVnode == NULL) return NULL;
   return pVnode->wqueue;
 }