refactor: do some internal refactor and add the sample code.

examples/c/tmq.c

@@ -20,7 +20,8 @@
 #include <time.h>
 #include "taos.h"
 
-static int running = 1;
+static int  running = 1;
+const char* topic_name = "topicname";
 
 static int32_t msg_process(TAOS_RES* msg) {
   char    buf[1024];
@@ -243,7 +244,7 @@ _end:
 
 tmq_list_t* build_topic_list() {
   tmq_list_t* topicList = tmq_list_new();
-  int32_t     code = tmq_list_append(topicList, "topicname");
+  int32_t     code = tmq_list_append(topicList, topic_name);
   if (code) {
     tmq_list_destroy(topicList);
     return NULL;
@@ -269,6 +270,31 @@ void basic_consume_loop(tmq_t* tmq) {
   fprintf(stderr, "%d msg consumed, include %d rows\n", msgCnt, totalRows);
 }
 
+void consume_repeatly(tmq_t* tmq) {
+  int32_t               numOfAssignment = 0;
+  tmq_topic_assignment* pAssign = NULL;
+
+  int32_t code = tmq_get_topic_assignment(tmq, topic_name, &pAssign, &numOfAssignment);
+  if (code != 0) {
+    fprintf(stderr, "failed to get assignment, reason:%s", tmq_err2str(code));
+  }
+
+  // seek to the earliest offset
+  for(int32_t i = 0; i < numOfAssignment; ++i) {
+    tmq_topic_assignment* p = &pAssign[i];
+
+    code = tmq_offset_seek(tmq, topic_name, p->vgId, p->begin);
+    if (code != 0) {
+      fprintf(stderr, "failed to seek to %ld, reason:%s", p->begin, tmq_err2str(code));
+    }
+  }
+
+  free(pAssign);
+
+  // let's do it again
+  basic_consume_loop(tmq);
+}
+
 int main(int argc, char* argv[]) {
   int32_t code;
 
@@ -294,10 +320,13 @@ int main(int argc, char* argv[]) {
   if ((code = tmq_subscribe(tmq, topic_list))) {
     fprintf(stderr, "Failed to tmq_subscribe(): %s\n", tmq_err2str(code));
   }
+
   tmq_list_destroy(topic_list);
 
   basic_consume_loop(tmq);
 
+  consume_repeatly(tmq);
+
   code = tmq_consumer_close(tmq);
   if (code) {
     fprintf(stderr, "Failed to close consumer: %s\n", tmq_err2str(code));

include/client/taos.h

@@ -263,7 +263,7 @@ DLL_EXPORT const char *tmq_err2str(int32_t code);
 
 /* ------------------------TMQ CONSUMER INTERFACE------------------------ */
 typedef struct tmq_topic_assignment {
-  int32_t  vgroupHandle;
+  int32_t  vgId;
   int64_t  currentOffset;
   int64_t  begin;
   int64_t  end;
@@ -277,7 +277,7 @@ DLL_EXPORT int32_t   tmq_consumer_close(tmq_t *tmq);
 DLL_EXPORT int32_t   tmq_commit_sync(tmq_t *tmq, const TAOS_RES *msg);
 DLL_EXPORT void      tmq_commit_async(tmq_t *tmq, const TAOS_RES *msg, tmq_commit_cb *cb, void *param);
 DLL_EXPORT int32_t   tmq_get_topic_assignment(tmq_t *tmq, const char* pTopicName, tmq_topic_assignment **assignment, int32_t *numOfAssignment);
-DLL_EXPORT int32_t   tmq_offset_seek(tmq_t *tmq, const char* pTopicName, int32_t vgroupHandle, int64_t offset);
+DLL_EXPORT int32_t   tmq_offset_seek(tmq_t *tmq, const char* pTopicName, int32_t vgId, int64_t offset);
 
 /* ----------------------TMQ CONFIGURATION INTERFACE---------------------- */
 

source/client/src/clientTmq.c

@@ -2357,7 +2357,7 @@ static int32_t tmqGetWalInfoCb(void* param, SDataBuf* pMsg, int32_t code) {
     tmq_topic_assignment assignment = {.begin = pHead->walsver,
                                        .end = pHead->walever,
                                        .currentOffset = rsp.rspOffset.version,
-                                       .vgroupHandle = pParam->vgId};
+                                       .vgId = pParam->vgId};
 
     taosThreadMutexLock(&pCommon->mutex);
     taosArrayPush(pCommon->pList, &assignment);
@@ -2422,7 +2422,7 @@ int32_t tmq_get_topic_assignment(tmq_t* tmq, const char* pTopicName, tmq_topic_a
 
     pAssignment->begin = pClientVg->offsetInfo.walVerBegin;
     pAssignment->end = pClientVg->offsetInfo.walVerEnd;
-    pAssignment->vgroupHandle = pClientVg->vgId;
+    pAssignment->vgId = pClientVg->vgId;
   }
 
   if (needFetch) {
@@ -2524,7 +2524,7 @@ int32_t tmq_get_topic_assignment(tmq_t* tmq, const char* pTopicName, tmq_topic_a
   }
 }
 
-int32_t tmq_offset_seek(tmq_t* tmq, const char* pTopicName, int32_t vgroupHandle, int64_t offset) {
+int32_t tmq_offset_seek(tmq_t* tmq, const char* pTopicName, int32_t vgId, int64_t offset) {
   if (tmq == NULL) {
     tscError("invalid tmq handle, null");
     return TSDB_CODE_INVALID_PARA;
@@ -2544,14 +2544,14 @@ int32_t tmq_offset_seek(tmq_t* tmq, const char* pTopicName, int32_t vgroupHandle
   int32_t      numOfVgs = taosArrayGetSize(pTopic->vgs);
   for (int32_t i = 0; i < numOfVgs; ++i) {
     SMqClientVg* pClientVg = taosArrayGet(pTopic->vgs, i);
-    if (pClientVg->vgId == vgroupHandle) {
+    if (pClientVg->vgId == vgId) {
       pVg = pClientVg;
       break;
     }
   }
 
   if (pVg == NULL) {
-    tscError("consumer:0x%" PRIx64 " invalid vgroup id:%d", tmq->consumerId, vgroupHandle);
+    tscError("consumer:0x%" PRIx64 " invalid vgroup id:%d", tmq->consumerId, vgId);
     return TSDB_CODE_INVALID_PARA;
   }