Add unit test for ForwardFsyncRequest() to ComptactBgwriterRequestQueue().

src/backend/postmaster/test/Makefile

@@ -2,6 +2,7 @@ subdir=src/backend/postmaster
 top_builddir=../../../..
 include $(top_builddir)/src/Makefile.global
 
-TARGETS=syslogger
+TARGETS=syslogger bgwriter
 
 include $(top_builddir)/src/backend/mock.mk
+bgwriter.t: $(MOCK_DIR)/backend/storage/lmgr/lwlock_mock.o

src/backend/postmaster/test/bgwriter_test.c

+#include <stdarg.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include "cmockery.h"
+
+#include "c.h"
+#include "../bgwriter.c"
+#include "postgres.h"
+
+#define MAX_BGW_REQUESTS 5
+void
+init_request_queue(void)
+{
+	size_t size = sizeof(BgWriterShmemStruct) + sizeof(BgWriterRequest)*MAX_BGW_REQUESTS;
+	BgWriterShmem = (BgWriterShmemStruct *) malloc(size);
+	memset(BgWriterShmem, 0, size);
+	BgWriterShmem->bgwriter_pid = 1234;
+	BgWriterShmem->max_requests = MAX_BGW_REQUESTS;
+	IsUnderPostmaster = true;
+}
+
+/*
+ * Basic enqueue tests, including compaction upon enqueuing into a
+ * full queue.
+ */
+void
+test__ForwardFsyncRequest_enqueue(void **state)
+{
+	bool ret;
+	int i;
+	RelFileNode dummy = {1,1,1};
+	init_request_queue();
+	expect_value(LWLockAcquire, lockid, BgWriterCommLock);
+	expect_value(LWLockAcquire, mode, LW_EXCLUSIVE);
+	will_be_called(LWLockAcquire);
+	expect_value(LWLockRelease, lockid, BgWriterCommLock);
+	will_be_called(LWLockRelease);
+	/* basic enqueue */
+	ret = ForwardFsyncRequest(dummy, 1);
+	assert_true(ret);
+	assert_true(BgWriterShmem->num_requests == 1);
+	/* fill up the queue */
+	for (i=2; i<=MAX_BGW_REQUESTS; i++)
+	{
+		expect_value(LWLockAcquire, lockid, BgWriterCommLock);
+		expect_value(LWLockAcquire, mode, LW_EXCLUSIVE);
+		will_be_called(LWLockAcquire);
+		expect_value(LWLockRelease, lockid, BgWriterCommLock);
+		will_be_called(LWLockRelease);
+		ret = ForwardFsyncRequest(dummy, i);
+		assert_true(ret);
+	}
+	expect_value(LWLockAcquire, lockid, BgWriterCommLock);
+	expect_value(LWLockAcquire, mode, LW_EXCLUSIVE);
+	will_be_called(LWLockAcquire);
+	expect_value(LWLockRelease, lockid, BgWriterCommLock);
+	will_be_called(LWLockRelease);
+#ifdef USE_ASSERT_CHECKING
+	expect_value(LWLockHeldByMe, lockid, BgWriterCommLock);
+	will_return(LWLockHeldByMe, true);
+#endif
+	/*
+	 * This enqueue request should trigger compaction but no
+	 * duplicates are in the queue.  So the queue should remain
+	 * full.
+	 */
+	ret = ForwardFsyncRequest(dummy, 0);
+	assert_false(ret);
+	assert_true(BgWriterShmem->num_requests == BgWriterShmem->max_requests);
+	free(BgWriterShmem);
+}
+
+int
+main(int argc, char* argv[]) {
+	cmockery_parse_arguments(argc, argv);
+	MemoryContextInit();
+	const UnitTest tests[] = {
+		unit_test(test__ForwardFsyncRequest_enqueue)
+	};
+	return run_tests(tests);
+}