fix two bugs:

1. taos_consume block for evev
2. taos_fetch_block returns 0 in subscription

src/client/src/tscSql.c

@@ -344,7 +344,7 @@ int taos_fetch_block_impl(TAOS_RES *res, TAOS_ROW *rows) {
   SSqlRes *pRes = &pSql->res;
   STscObj *pObj = pSql->pTscObj;
 
-  if (pRes->qhandle == 0 || pObj->pSql != pSql) {
+  if (pRes->qhandle == 0) {
     *rows = NULL;
     return 0;
   }

src/client/src/tscSub.c

@@ -348,8 +348,8 @@ TAOS_RES *taos_consume(TAOS_SUB *tsub) {
   SSqlRes *pRes = &pSql->res;
 
   if (pSub->pTimer == NULL) {
-    int duration = (int)(taosGetTimestampMs() - pSub->lastConsumeTime);
-    if (duration < pSub->interval) {
+    int64_t duration = taosGetTimestampMs() - pSub->lastConsumeTime;
+    if (duration < (int64_t)(pSub->interval)) {
       tscTrace("subscription consume too frequently, blocking...");
       taosMsleep(pSub->interval - (int32_t)duration);
     }

tests/examples/c/subscribe.c

@@ -8,15 +8,28 @@
 #include <unistd.h>
 
 void print_result(TAOS_RES* res) {
-  TAOS_ROW    row;
+  TAOS_ROW    row = NULL;
   int         num_fields = taos_num_fields(res);
   TAOS_FIELD* fields = taos_fetch_fields(res);
 
+#if 0
+
+  int nRows = taos_fetch_block(res, &row);
+  for (int i = 0; i < nRows; i++) {
+    char temp[256];
+    taos_print_row(temp, row + i, fields, num_fields);
+    puts(temp);
+  }
+
+#else
+
   while ((row = taos_fetch_row(res))) {
     char temp[256];
     taos_print_row(temp, row, fields, num_fields);
     puts(temp);
   }
+
+#endif
 }
 
 void subscribe_callback(TAOS_SUB* tsub, TAOS_RES *res, void* param, int code) {