Variable latency when sending/receiving messages

Bug: 465369

src/MQTTAsync.c

@@ -24,6 +24,7 @@
  *    Ian Craggs - fix for bug 442400: reconnecting after network cable unplugged
  *    Ian Craggs - fix for bug 444934 - incorrect free in freeCommand1
  *    Ian Craggs - fix for bug 445891 - assigning msgid is not thread safe
+ *    Ian Craggs - fix for bug 465369 - longer latency than expected
  *******************************************************************************/
 
 /**
@@ -137,6 +138,11 @@ void MQTTAsync_init()
 		printf("MQTTAsync: error %d initializing async_mutex\n", rc);
 	if ((rc = pthread_mutex_init(mqttcommand_mutex, &attr)) != 0)
 		printf("MQTTAsync: error %d initializing command_mutex\n", rc);
+
+	if ((rc = pthread_cond_init(&send_cond->cond, NULL)) != 0)
+		printf("MQTTAsync: error %d initializing send_cond cond\n", rc);
+	if ((rc = pthread_mutex_init(&send_cond->mutex, &attr)) != 0)
+		printf("MQTTAsync: error %d initializing send_cond mutex\n", rc);
 }
 
 #define WINAPI
@@ -760,7 +766,9 @@ int MQTTAsync_addCommand(MQTTAsync_queuedCommand* command, int command_size)
 	}
 	MQTTAsync_unlock_mutex(mqttcommand_mutex);
 #if !defined(WIN32) && !defined(WIN64)
-	Thread_signal_cond(send_cond);
+	rc = Thread_signal_cond(send_cond);
+	if (rc != 0)
+		Log(LOG_ERROR, 0, "Error %d from signal cond", rc);
 #else
 	if (!Thread_check_sem(send_sem))
 		Thread_post_sem(send_sem);
@@ -927,7 +935,7 @@ void MQTTAsync_writeComplete(int socket)
 }
 			
 
-void MQTTAsync_processCommand()
+int MQTTAsync_processCommand()
 {
 	int rc = 0;
 	MQTTAsync_queuedCommand* command = NULL;
@@ -1166,7 +1174,9 @@ void MQTTAsync_processCommand()
 
 exit:
 	MQTTAsync_unlock_mutex(mqttasync_mutex);
-	FUNC_EXIT;
+	rc = (command != NULL);
+	FUNC_EXIT_RC(rc);
+	return rc;
 }
 
 
@@ -1265,13 +1275,10 @@ thread_return_type WINAPI MQTTAsync_sendThread(void* n)
 		
 		while (commands->count > 0)
 		{
-			int before = commands->count;
-			MQTTAsync_processCommand();
-			if (before == commands->count)
+			if (MQTTAsync_processCommand() == 0)
 				break;  /* no commands were processed, so go into a wait */
 		}
 #if !defined(WIN32) && !defined(WIN64)
-		rc =  Thread_wait_cond(send_cond, 1);
 		if ((rc = Thread_wait_cond(send_cond, 1)) != 0 && rc != ETIMEDOUT)
 			Log(LOG_ERROR, -1, "Error %d waiting for condition variable", rc);
 #else