test_shm_mq: Replace WAIT_EVENT_EXTENSION with custom wait events

Two custom wait events are added here:
- "TestShmMqBgWorkerStartup", when setting up a set of bgworkers in
wait_for_workers_to_become_ready().
- "TestShmMqMessageQueue", when waiting for a queued message in
test_shm_mq_pipelined().

Author: Masahiro Ikeda
Discussion: https://postgr.es/m/197bce267fa691a0ac62c86c4ab904c4@oss.nttdata.com

src/test/modules/test_shm_mq/setup.c

@@ -40,6 +40,9 @@ static void wait_for_workers_to_become_ready(worker_state *wstate,
 											 volatile test_shm_mq_header *hdr);
 static bool check_worker_status(worker_state *wstate);
 
+/* value cached, fetched from shared memory */
+static uint32 we_bgworker_startup = 0;
+
 /*
  * Set up a dynamic shared memory segment and zero or more background workers
  * for a test run.
@@ -278,9 +281,13 @@ wait_for_workers_to_become_ready(worker_state *wstate,
 			break;
 		}
 
+		/* first time, allocate or get the custom wait event */
+		if (we_bgworker_startup == 0)
+			we_bgworker_startup = WaitEventExtensionNew("TestShmMqBgWorkerStartup");
+
 		/* Wait to be signaled. */
 		(void) WaitLatch(MyLatch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH, 0,
-						 WAIT_EVENT_EXTENSION);
+						 we_bgworker_startup);
 
 		/* Reset the latch so we don't spin. */
 		ResetLatch(MyLatch);

src/test/modules/test_shm_mq/test.c

@@ -28,6 +28,9 @@ PG_FUNCTION_INFO_V1(test_shm_mq_pipelined);
 static void verify_message(Size origlen, char *origdata, Size newlen,
 						   char *newdata);
 
+/* value cached, fetched from shared memory */
+static uint32 we_message_queue = 0;
+
 /*
  * Simple test of the shared memory message queue infrastructure.
  *
@@ -225,6 +228,10 @@ test_shm_mq_pipelined(PG_FUNCTION_ARGS)
 
 		if (wait)
 		{
+			/* first time, allocate or get the custom wait event */
+			if (we_message_queue == 0)
+				we_message_queue = WaitEventExtensionNew("TestShmMqMessageQueue");
+
 			/*
 			 * If we made no progress, wait for one of the other processes to
 			 * which we are connected to set our latch, indicating that they
@@ -232,7 +239,7 @@ test_shm_mq_pipelined(PG_FUNCTION_ARGS)
 			 * for us to do.
 			 */
 			(void) WaitLatch(MyLatch, WL_LATCH_SET | WL_EXIT_ON_PM_DEATH, 0,
-							 WAIT_EVENT_EXTENSION);
+							 we_message_queue);
 			ResetLatch(MyLatch);
 			CHECK_FOR_INTERRUPTS();
 		}