Subject: [PATCH v8 5/5] wip: instr_time: Add and use INSTR_TIME_ZERO(), INSTR_TIME_CURRENT()

From: Andres Freund <[email-masked]>
Date: Fri, 20 Jan 2023 16:09:37 -0800

This just updates the places that "Zero initialize instr_time uses causing
compiler warnings" changed, to see whether this is a nicer approach.
---
 src/include/portability/instr_time.h | 24 ++++++++++++++------
 src/backend/access/transam/xlog.c    | 11 +++-------
 src/backend/storage/buffer/bufmgr.c  | 16 +++++---------
 src/backend/storage/file/buffile.c   | 16 +++++---------
 src/backend/storage/ipc/latch.c      |  8 +++----
 src/bin/psql/common.c                | 33 +++++++++++++---------------
 6 files changed, 50 insertions(+), 58 deletions(-)

diff --git a/src/include/portability/instr_time.h b/src/include/portability/instr_time.h
index af2ab6ec887..2d1ff4f7f82 100644
--- a/src/include/portability/instr_time.h
+++ b/src/include/portability/instr_time.h
@@ -17,6 +17,10 @@
  *
  * INSTR_TIME_IS_LT(x, y)			x < y
  *
+ * INSTR_TIME_ZERO()				an instr_time set to 0
+ *
+ * INSTR_TIME_CURRENT()				an instr_time set to current time
+ *
  * INSTR_TIME_SET_ZERO(t)			set t to zero (memset is acceptable too)
  *
  * INSTR_TIME_SET_CURRENT(t)		set t to current time
@@ -110,7 +114,7 @@ typedef struct instr_time
 #define PG_INSTR_CLOCK	CLOCK_REALTIME
 #endif
 
-/* helper for INSTR_TIME_SET_CURRENT */
+/* helper for INSTR_TIME_CURRENT */
 static inline instr_time
 pg_clock_gettime_ns(void)
 {
@@ -123,8 +127,8 @@ pg_clock_gettime_ns(void)
 	return now;
 }
 
-#define INSTR_TIME_SET_CURRENT(t) \
-	((t) = pg_clock_gettime_ns())
+#define INSTR_TIME_CURRENT(t) \
+	pg_clock_gettime_ns()
 
 #define INSTR_TIME_SET_SECONDS(t, s) \
 	((t).ticks = NS_PER_S * (s))
@@ -138,7 +142,7 @@ pg_clock_gettime_ns(void)
 
 /* Use QueryPerformanceCounter() */
 
-/* helper for INSTR_TIME_SET_CURRENT */
+/* helper for INSTR_TIME_CURRENT */
 static inline instr_time
 pg_query_performance_counter(void)
 {
@@ -160,8 +164,8 @@ GetTimerFrequency(void)
 	return (double) f.QuadPart;
 }
 
-#define INSTR_TIME_SET_CURRENT(t) \
-	((t) = pg_query_performance_counter())
+#define INSTR_TIME_CURRENT(t) \
+	pg_query_performance_counter()
 
 #define INSTR_TIME_SET_SECONDS(t, s) \
 	((t).ticks = s * GetTimerFrequency())
@@ -181,7 +185,13 @@ GetTimerFrequency(void)
 #define INSTR_TIME_IS_LT(x, y)	((x).ticks < (y).ticks)

-#define INSTR_TIME_SET_ZERO(t)	((t).ticks = 0)
+#define INSTR_TIME_ZERO(t)	(instr_time){0}
+
+#define INSTR_TIME_SET_CURRENT(t) \
+	(t) = INSTR_TIME_CURRENT()
+
+#define INSTR_TIME_SET_ZERO(t) \
+	((t) = INSTR_TIME_ZERO())
 
 #define INSTR_TIME_SET_CURRENT_LAZY(t) \
 	(INSTR_TIME_IS_ZERO(t) ? INSTR_TIME_SET_CURRENT(t), true : false)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index fb4c860bdea..f563800c8ab 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2178,7 +2178,7 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
 			Size		nbytes;
 			Size		nleft;
 			int			written;
-			instr_time	start;
+			instr_time	start = INSTR_TIME_ZERO();
 
 			/* OK to write the page(s) */
 			from = XLogCtl->pages + startidx * (Size) XLOG_BLCKSZ;
@@ -2191,8 +2191,6 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
 				/* Measure I/O timing to write WAL data */
 				if (track_wal_io_timing)
 					INSTR_TIME_SET_CURRENT(start);
-				else
-					INSTR_TIME_SET_ZERO(start);
 
 				pgstat_report_wait_start(WAIT_EVENT_WAL_WRITE);
 				written = pg_pwrite(openLogFile, from, nleft, startoffset);
@@ -2204,9 +2202,8 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
 				 */
 				if (track_wal_io_timing)
 				{
-					instr_time	duration;
+					instr_time	duration = INSTR_TIME_CURRENT();
 
-					INSTR_TIME_SET_CURRENT(duration);
 					INSTR_TIME_SUBTRACT(duration, start);
 					PendingWalStats.wal_write_time += INSTR_TIME_GET_MICROSEC(duration);
 				}
@@ -8137,7 +8134,7 @@ void
 issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
 {
 	char	   *msg = NULL;
-	instr_time	start;
+	instr_time	start = INSTR_TIME_ZERO();
 
 	Assert(tli != 0);
 
@@ -8153,8 +8150,6 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
 	/* Measure I/O timing to sync the WAL file */
 	if (track_wal_io_timing)
 		INSTR_TIME_SET_CURRENT(start);
-	else
-		INSTR_TIME_SET_ZERO(start);
 
 	pgstat_report_wait_start(WAIT_EVENT_WAL_SYNC);
 	switch (sync_method)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 800a4248c95..d8baf80e650 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1012,19 +1012,17 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
 			MemSet((char *) bufBlock, 0, BLCKSZ);
 		else
 		{
-			instr_time	io_start,
-						io_time;
+			instr_time	io_start = INSTR_TIME_ZERO();
 
 			if (track_io_timing)
 				INSTR_TIME_SET_CURRENT(io_start);
-			else
-				INSTR_TIME_SET_ZERO(io_start);
 
 			smgrread(smgr, forkNum, blockNum, (char *) bufBlock);
 
 			if (track_io_timing)
 			{
-				INSTR_TIME_SET_CURRENT(io_time);
+				instr_time	io_time = INSTR_TIME_CURRENT();
+
 				INSTR_TIME_SUBTRACT(io_time, io_start);
 				pgstat_count_buffer_read_time(INSTR_TIME_GET_MICROSEC(io_time));
 				INSTR_TIME_ADD(pgBufferUsage.blk_read_time, io_time);
@@ -2826,8 +2824,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln)
 {
 	XLogRecPtr	recptr;
 	ErrorContextCallback errcallback;
-	instr_time	io_start,
-				io_time;
+	instr_time	io_start = INSTR_TIME_ZERO();
 	Block		bufBlock;
 	char	   *bufToWrite;
 	uint32		buf_state;
@@ -2904,8 +2901,6 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln)
 
 	if (track_io_timing)
 		INSTR_TIME_SET_CURRENT(io_start);
-	else
-		INSTR_TIME_SET_ZERO(io_start);
 
 	/*
 	 * bufToWrite is either the shared buffer or a copy, as appropriate.
@@ -2918,7 +2913,8 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln)
 
 	if (track_io_timing)
 	{
-		INSTR_TIME_SET_CURRENT(io_time);
+		instr_time	io_time = INSTR_TIME_CURRENT();
+
 		INSTR_TIME_SUBTRACT(io_time, io_start);
 		pgstat_count_buffer_write_time(INSTR_TIME_GET_MICROSEC(io_time));
 		INSTR_TIME_ADD(pgBufferUsage.blk_write_time, io_time);
diff --git a/src/backend/storage/file/buffile.c b/src/backend/storage/file/buffile.c
index 0a51624df3b..6f813279690 100644
--- a/src/backend/storage/file/buffile.c
+++ b/src/backend/storage/file/buffile.c
@@ -429,8 +429,7 @@ static void
 BufFileLoadBuffer(BufFile *file)
 {
 	File		thisfile;
-	instr_time	io_start;
-	instr_time	io_time;
+	instr_time	io_start = INSTR_TIME_ZERO();
 
 	/*
 	 * Advance to next component file if necessary and possible.
@@ -446,8 +445,6 @@ BufFileLoadBuffer(BufFile *file)
 
 	if (track_io_timing)
 		INSTR_TIME_SET_CURRENT(io_start);
-	else
-		INSTR_TIME_SET_ZERO(io_start);
 
 	/*
 	 * Read whatever we can get, up to a full bufferload.
@@ -468,7 +465,8 @@ BufFileLoadBuffer(BufFile *file)
 
 	if (track_io_timing)
 	{
-		INSTR_TIME_SET_CURRENT(io_time);
+		instr_time	io_time = INSTR_TIME_CURRENT();
+
 		INSTR_TIME_SUBTRACT(io_time, io_start);
 		INSTR_TIME_ADD(pgBufferUsage.temp_blk_read_time, io_time);
 	}
@@ -500,8 +498,7 @@ BufFileDumpBuffer(BufFile *file)
 	while (wpos < file->nbytes)
 	{
 		off_t		availbytes;
-		instr_time	io_start;
-		instr_time	io_time;
+		instr_time	io_start = INSTR_TIME_ZERO();
 
 		/*
 		 * Advance to next component file if necessary and possible.
@@ -527,8 +524,6 @@ BufFileDumpBuffer(BufFile *file)
 
 		if (track_io_timing)
 			INSTR_TIME_SET_CURRENT(io_start);
-		else
-			INSTR_TIME_SET_ZERO(io_start);
 
 		bytestowrite = FileWrite(thisfile,
 								 file->buffer.data + wpos,
@@ -543,7 +538,8 @@ BufFileDumpBuffer(BufFile *file)
 
 		if (track_io_timing)
 		{
-			INSTR_TIME_SET_CURRENT(io_time);
+			instr_time	io_time = INSTR_TIME_CURRENT();
+
 			INSTR_TIME_SUBTRACT(io_time, io_start);
 			INSTR_TIME_ADD(pgBufferUsage.temp_blk_write_time, io_time);
 		}
diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c
index f4123e7de7e..8092ff4a984 100644
--- a/src/backend/storage/ipc/latch.c
+++ b/src/backend/storage/ipc/latch.c
@@ -1385,8 +1385,7 @@ WaitEventSetWait(WaitEventSet *set, long timeout,
 				 uint32 wait_event_info)
 {
 	int			returned_events = 0;
-	instr_time	start_time;
-	instr_time	cur_time;
+	instr_time	start_time = INSTR_TIME_ZERO();
 	long		cur_timeout = -1;
 
 	Assert(nevents > 0);
@@ -1401,8 +1400,6 @@ WaitEventSetWait(WaitEventSet *set, long timeout,
 		Assert(timeout >= 0 && timeout <= INT_MAX);
 		cur_timeout = timeout;
 	}
-	else
-		INSTR_TIME_SET_ZERO(start_time);
 
 	pgstat_report_wait_start(wait_event_info);
 
@@ -1489,7 +1486,8 @@ WaitEventSetWait(WaitEventSet *set, long timeout,
 		/* If we're not done, update cur_timeout for next iteration */
 		if (returned_events == 0 && timeout >= 0)
 		{
-			INSTR_TIME_SET_CURRENT(cur_time);
+			instr_time	cur_time = INSTR_TIME_CURRENT();
+
 			INSTR_TIME_SUBTRACT(cur_time, start_time);
 			cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
 			if (cur_timeout <= 0)
diff --git a/src/bin/psql/common.c b/src/bin/psql/common.c
index f907f5d4e8d..5badb029e83 100644
--- a/src/bin/psql/common.c
+++ b/src/bin/psql/common.c
@@ -1269,15 +1269,12 @@ DescribeQuery(const char *query, double *elapsed_msec)
 	bool		timing = pset.timing;
 	PGresult   *result;
 	bool		OK;
-	instr_time	before,
-				after;
+	instr_time	before = INSTR_TIME_ZERO();
 
 	*elapsed_msec = 0;
 
 	if (timing)
 		INSTR_TIME_SET_CURRENT(before);
-	else
-		INSTR_TIME_SET_ZERO(before);
 
 	/*
 	 * To parse the query but not execute it, we prepare it, using the unnamed
@@ -1350,7 +1347,8 @@ DescribeQuery(const char *query, double *elapsed_msec)
 
 			if (timing)
 			{
-				INSTR_TIME_SET_CURRENT(after);
+				instr_time	after = INSTR_TIME_CURRENT();
+
 				INSTR_TIME_SUBTRACT(after, before);
 				*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
 			}
@@ -1400,16 +1398,13 @@ ExecQueryAndProcessResults(const char *query,
 {
 	bool		timing = pset.timing;
 	bool		success;
-	instr_time	before,
-				after;
+	instr_time	before = INSTR_TIME_ZERO();
 	PGresult   *result;
 	FILE	   *gfile_fout = NULL;
 	bool		gfile_is_pipe = false;
 
 	if (timing)
 		INSTR_TIME_SET_CURRENT(before);
-	else
-		INSTR_TIME_SET_ZERO(before);
 
 	if (pset.bind_flag)
 		success = PQsendQueryParams(pset.db, query, pset.bind_nparams, NULL, (const char * const *) pset.bind_params, NULL, NULL, 0);
@@ -1490,7 +1485,8 @@ ExecQueryAndProcessResults(const char *query,
 			 */
 			if (timing)
 			{
-				INSTR_TIME_SET_CURRENT(after);
+				instr_time	after = INSTR_TIME_CURRENT();
+
 				INSTR_TIME_SUBTRACT(after, before);
 				*elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
 			}
@@ -1595,7 +1591,8 @@ ExecQueryAndProcessResults(const char *query,
 		 */
 		if (timing)
 		{
-			INSTR_TIME_SET_CURRENT(after);
+			instr_time	after = INSTR_TIME_CURRENT();
+
 			INSTR_TIME_SUBTRACT(after, before);
 			*elapsed_msec = INSTR_TIME_GET_MILLISEC(after);
 		}
@@ -1693,8 +1690,7 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
 	int			ntuples;
 	int			fetch_count;
 	char		fetch_cmd[64];
-	instr_time	before,
-				after;
+	instr_time	before = INSTR_TIME_ZERO();
 	int			flush_error;
 
 	*elapsed_msec = 0;
@@ -1706,8 +1702,6 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
 
 	if (timing)
 		INSTR_TIME_SET_CURRENT(before);
-	else
-		INSTR_TIME_SET_ZERO(before);
 
 	/* if we're not in a transaction, start one */
 	if (PQtransactionStatus(pset.db) == PQTRANS_IDLE)
@@ -1738,7 +1732,8 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
 
 	if (timing)
 	{
-		INSTR_TIME_SET_CURRENT(after);
+		instr_time	after = INSTR_TIME_CURRENT();
+
 		INSTR_TIME_SUBTRACT(after, before);
 		*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
 	}
@@ -1786,7 +1781,8 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
 
 		if (timing)
 		{
-			INSTR_TIME_SET_CURRENT(after);
+			instr_time	after = INSTR_TIME_CURRENT();
+
 			INSTR_TIME_SUBTRACT(after, before);
 			*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
 		}
@@ -1926,7 +1922,8 @@ cleanup:
 
 	if (timing)
 	{
-		INSTR_TIME_SET_CURRENT(after);
+		instr_time	after = INSTR_TIME_CURRENT();
+
 		INSTR_TIME_SUBTRACT(after, before);
 		*elapsed_msec += INSTR_TIME_GET_MILLISEC(after);
 	}
-- 
2.38.0

--vt42kbp2j7rjcapp--