instr_time.h: add INSTR_TIME_SET_CURRENT_LAZY

alvherre · alvherre · commit 6f7d02aa60b7 · 2018-11-21T15:04:25.000-03:00
Sets the timestamp to current if not already set. Will acquire more callers momentarily. Author: Fabien Coelho Discussion: https://postgr.es/m/alpine.DEB.2.21.1808111104320.1705@lancre
diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
@@ -62,13 +62,9 @@ InstrInit(Instrumentation *instr, int instrument_options)
 void
 InstrStartNode(Instrumentation *instr)
 {
-	if (instr->need_timer)
-	{
-		if (INSTR_TIME_IS_ZERO(instr->starttime))
-			INSTR_TIME_SET_CURRENT(instr->starttime);
-		else
-			elog(ERROR, "InstrStartNode called twice in a row");
-	}
+	if (instr->need_timer &&
+		INSTR_TIME_SET_CURRENT_LAZY(instr->starttime))
+		elog(ERROR, "InstrStartNode called twice in a row");
 
 	/* save buffer usage totals at node entry, if needed */
 	if (instr->need_bufusage)
diff --git a/src/include/portability/instr_time.h b/src/include/portability/instr_time.h
@@ -20,6 +20,9 @@
  *
  * INSTR_TIME_SET_CURRENT(t)		set t to current time
  *
+ * INSTR_TIME_SET_CURRENT_LAZY(t)	set t to current time if t is zero,
+ *									evaluates to whether t changed
+ *
  * INSTR_TIME_ADD(x, y)				x += y
  *
  * INSTR_TIME_SUBTRACT(x, y)		x -= y
@@ -245,4 +248,9 @@ GetTimerFrequency(void)
 
 #endif							/* WIN32 */
 
+/* same macro on all platforms */
+
+#define INSTR_TIME_SET_CURRENT_LAZY(t) \
+	(INSTR_TIME_IS_ZERO(t) ? INSTR_TIME_SET_CURRENT(t), true : false)
+
 #endif							/* INSTR_TIME_H */

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,9 @@`
`20`	`20`	`*`
`21`	`21`	`* INSTR_TIME_SET_CURRENT(t) set t to current time`
`22`	`22`	`*`
	`23`	`+ * INSTR_TIME_SET_CURRENT_LAZY(t) set t to current time if t is zero,`
	`24`	`+ * evaluates to whether t changed`
	`25`	`+ *`
`23`	`26`	`* INSTR_TIME_ADD(x, y) x += y`
`24`	`27`	`*`
`25`	`28`	`* INSTR_TIME_SUBTRACT(x, y) x -= y`
`@@ -245,4 +248,9 @@ GetTimerFrequency(void)`
`245`	`248`
`246`	`249`	`#endif /* WIN32 */`
`247`	`250`
	`251`	`+/* same macro on all platforms */`
	`252`	`+`
	`253`	`+#define INSTR_TIME_SET_CURRENT_LAZY(t) \`
	`254`	`+ (INSTR_TIME_IS_ZERO(t) ? INSTR_TIME_SET_CURRENT(t), true : false)`
	`255`	`+`
`248`	`256`	`#endif /* INSTR_TIME_H */`