Expose BufferUsageAccumDiff().

MasaoFujii · MasaoFujii · commit 4a539a25ebfc · 2020-03-30T12:15:26.000+09:00
Previously pg_stat_statements calculated the difference of buffer counters by its own code even while BufferUsageAccumDiff() had the same code. This commit expose BufferUsageAccumDiff() and makes pg_stat_statements use it for the calculation, in order to simply the code. This change also would be useful for the upcoming patch for the planning counters in pg_stat_statements because the patch will add one more code for the calculation of difference of buffer counters and that can easily be done by using BufferUsageAccumDiff(). Author: Julien Rouhaud Reviewed-by: Fujii Masao Discussion: https://postgr.es/m/bdfee4e0-a304-2498-8da5-3cb52c0a193e@oss.nttdata.com
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -1016,30 +1016,8 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
 		rows = (qc && qc->commandTag == CMDTAG_COPY) ? qc->nprocessed : 0;
 
 		/* calc differences of buffer counters. */
-		bufusage.shared_blks_hit =
-			pgBufferUsage.shared_blks_hit - bufusage_start.shared_blks_hit;
-		bufusage.shared_blks_read =
-			pgBufferUsage.shared_blks_read - bufusage_start.shared_blks_read;
-		bufusage.shared_blks_dirtied =
-			pgBufferUsage.shared_blks_dirtied - bufusage_start.shared_blks_dirtied;
-		bufusage.shared_blks_written =
-			pgBufferUsage.shared_blks_written - bufusage_start.shared_blks_written;
-		bufusage.local_blks_hit =
-			pgBufferUsage.local_blks_hit - bufusage_start.local_blks_hit;
-		bufusage.local_blks_read =
-			pgBufferUsage.local_blks_read - bufusage_start.local_blks_read;
-		bufusage.local_blks_dirtied =
-			pgBufferUsage.local_blks_dirtied - bufusage_start.local_blks_dirtied;
-		bufusage.local_blks_written =
-			pgBufferUsage.local_blks_written - bufusage_start.local_blks_written;
-		bufusage.temp_blks_read =
-			pgBufferUsage.temp_blks_read - bufusage_start.temp_blks_read;
-		bufusage.temp_blks_written =
-			pgBufferUsage.temp_blks_written - bufusage_start.temp_blks_written;
-		bufusage.blk_read_time = pgBufferUsage.blk_read_time;
-		INSTR_TIME_SUBTRACT(bufusage.blk_read_time, bufusage_start.blk_read_time);
-		bufusage.blk_write_time = pgBufferUsage.blk_write_time;
-		INSTR_TIME_SUBTRACT(bufusage.blk_write_time, bufusage_start.blk_write_time);
+		memset(&bufusage, 0, sizeof(BufferUsage));
+		BufferUsageAccumDiff(&bufusage, &pgBufferUsage, &bufusage_start);
 
 		pgss_store(queryString,
 				   0,			/* signal that it's a utility stmt */
diff --git a/src/backend/executor/instrument.c b/src/backend/executor/instrument.c
@@ -21,8 +21,6 @@ BufferUsage pgBufferUsage;
 static BufferUsage save_pgBufferUsage;
 
 static void BufferUsageAdd(BufferUsage *dst, const BufferUsage *add);
-static void BufferUsageAccumDiff(BufferUsage *dst,
-								 const BufferUsage *add, const BufferUsage *sub);
 
 
 /* Allocate new instrumentation structure(s) */
@@ -203,7 +201,7 @@ BufferUsageAdd(BufferUsage *dst, const BufferUsage *add)
 }
 
 /* dst += add - sub */
-static void
+void
 BufferUsageAccumDiff(BufferUsage *dst,
 					 const BufferUsage *add,
 					 const BufferUsage *sub)
diff --git a/src/include/executor/instrument.h b/src/include/executor/instrument.h
@@ -81,5 +81,7 @@ extern void InstrAggNode(Instrumentation *dst, Instrumentation *add);
 extern void InstrStartParallelQuery(void);
 extern void InstrEndParallelQuery(BufferUsage *result);
 extern void InstrAccumParallelQuery(BufferUsage *result);
+extern void BufferUsageAccumDiff(BufferUsage *dst,
+								 const BufferUsage *add, const BufferUsage *sub);
 
 #endif							/* INSTRUMENT_H */
