Rename variable for code clarity

danielgustafsson · danielgustafsson · commit a396e20ad0da · 2023-09-15T19:05:57.000+02:00
When tracking IO timing for WAL, the duration is what we calculate based on the start and end timestamps, it's not what the variable contains. Rename the timestamp variable to end to better communicate what it contains. Original patch by Krishnakumar with additional hacking to fix another occurrence by me. Author: Krishnakumar R <kksrcv001@gmail.com> Discussion: https://postgr.es/m/CAPMWgZ9f9o8awrQpjo8oxnNQ=bMDVPx00NE0QcDzvHD_ZrdLPw@mail.gmail.com
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
@@ -2226,10 +2226,10 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
 				 */
 				if (track_wal_io_timing)
 				{
-					instr_time	duration;
+					instr_time	end;
 
-					INSTR_TIME_SET_CURRENT(duration);
-					INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, duration, start);
+					INSTR_TIME_SET_CURRENT(end);
+					INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, end, start);
 				}
 
 				PendingWalStats.wal_write++;
@@ -8252,10 +8252,10 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
 	 */
 	if (track_wal_io_timing)
 	{
-		instr_time	duration;
+		instr_time	end;
 
-		INSTR_TIME_SET_CURRENT(duration);
-		INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, duration, start);
+		INSTR_TIME_SET_CURRENT(end);
+		INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, end, start);
 	}
 
 	PendingWalStats.wal_sync++;

Original file line number	Diff line number	Diff line change
`@@ -2226,10 +2226,10 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)`
`2226`	`2226`	`*/`
`2227`	`2227`	`if (track_wal_io_timing)`
`2228`	`2228`	`{`
`2229`		`- instr_time duration;`
	`2229`	`+ instr_time end;`
`2230`	`2230`
`2231`		`- INSTR_TIME_SET_CURRENT(duration);`
`2232`		`- INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, duration, start);`
	`2231`	`+ INSTR_TIME_SET_CURRENT(end);`
	`2232`	`+ INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, end, start);`
`2233`	`2233`	`}`
`2234`	`2234`
`2235`	`2235`	`PendingWalStats.wal_write++;`
`@@ -8252,10 +8252,10 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)`
`8252`	`8252`	`*/`
`8253`	`8253`	`if (track_wal_io_timing)`
`8254`	`8254`	`{`
`8255`		`- instr_time duration;`
	`8255`	`+ instr_time end;`
`8256`	`8256`
`8257`		`- INSTR_TIME_SET_CURRENT(duration);`
`8258`		`- INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, duration, start);`
	`8257`	`+ INSTR_TIME_SET_CURRENT(end);`
	`8258`	`+ INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, end, start);`
`8259`	`8259`	`}`
`8260`	`8260`
`8261`	`8261`	`PendingWalStats.wal_sync++;`