Checking the data stream on both ends doesn’t apply to frontend connections, since response data is buffered during extended queries.

Fixed TAP test

lib/PgSQL_Data_Stream.cpp

@@ -438,7 +438,8 @@ void PgSQL_Data_Stream::shut_hard() {
 }
 
 void PgSQL_Data_Stream::check_data_flow() {
-	if ((PSarrayIN->len || queue_data(queueIN)) && (PSarrayOUT->len || queue_data(queueOUT))) {
+	// This does not apply to frontend data streams because response data is buffered during extended queries.
+	if ((myds_type != MYDS_FRONTEND) && (PSarrayIN->len || queue_data(queueIN)) && (PSarrayOUT->len || queue_data(queueOUT))) {
 		// there is data at both sides of the data stream: this is considered a fatal error
 		proxy_error("Session=%p, DataStream=%p -- Data at both ends of a PgSQL data stream: IN <%d bytes %d packets> , OUT <%d bytes %d packets>\n", sess, this, PSarrayIN->len, queue_data(queueIN), PSarrayOUT->len, queue_data(queueOUT));
 		shut_soft();

test/tap/tests/pgsql-extended_query_protocol_query_rules_test-t.cpp

@@ -152,65 +152,55 @@ void consume_results(PGconn* conn) {
     PGresult* res = nullptr;
     bool saw_error = false;
     std::string errmsg;
+
+    // Keep looping until PQgetResult() returns NULL and
+    // connection is not busy anymore.
     for (;;) {
-        // Drain all immediately available results
         while ((res = PQgetResult(conn)) != nullptr) {
             ExecStatusType status = PQresultStatus(res);
             if (status == PGRES_FATAL_ERROR) {
                 saw_error = true;
                 errmsg = PQresultErrorMessage(res);
             }
-            if (status == PGRES_PIPELINE_ABORTED) {
-                // If pipeline was aborted, we need to clear the error
+            else if (status == PGRES_PIPELINE_ABORTED) {
                 saw_error = true;
-                errmsg = std::string("Pipeline aborted : ") + PQresultErrorMessage(res);
+                errmsg = std::string("Pipeline aborted: ") + PQresultErrorMessage(res);
             }
             PQclear(res);
         }
 
         if (!PQisBusy(conn)) {
-            while ((res = PQgetResult(conn)) != nullptr) {
+            // Ensure all results are drained
+            while ((res = PQgetResult(conn)) != nullptr)
                 PQclear(res);
-            }
-            break;  // ReadyForQuery reached
+            break;
         }
 
-        // ---- handle flushing + reading ----
-        int f = PQflush(conn);
-        if (f == -1) {
+        if (PQflush(conn) == -1) {
             throw std::runtime_error(std::string("PQflush failed: ") + PQerrorMessage(conn));
         }
 
-        short events = POLLIN;
-        if (f == 1) {
-            // still data to send  also watch POLLOUT
-            events |= POLLOUT;
-        }
-
         struct pollfd pfd;
         pfd.fd = PQsocket(conn);
-        pfd.events = events;
-        if (pfd.fd < 0) {
+        pfd.events = POLLIN | POLLOUT;
+        if (pfd.fd < 0)
             throw std::runtime_error("Invalid PostgreSQL socket");
-        }
 
-        if (poll(&pfd, 1, -1) < 0) {
+        if (poll(&pfd, 1, -1) < 0)
             throw std::runtime_error("poll() failed");
-        }
 
-        // If socket readable  consume input
-        if (pfd.revents & POLLIN) {
-            if (PQconsumeInput(conn) == 0) {
-                throw std::runtime_error(
-                    std::string("PQconsumeInput failed: ") + PQerrorMessage(conn));
-            }
+        if ((pfd.revents & POLLIN) && PQconsumeInput(conn) == 0) {
+            throw std::runtime_error(std::string("PQconsumeInput failed: ") + PQerrorMessage(conn));
         }
-        // If socket writable and f==1  PQflush() will be retried on next iteration
     }
 
     if (saw_error) {
         throw std::runtime_error("PostgreSQL error: " + errmsg);
     }
+
+    // call PQgetResult() one final time to clear any leftover
+    while ((res = PQgetResult(conn)) != nullptr)
+        PQclear(res);
 }
 
 void test_query_processor(PGconn* admin_conn) {