Represent command completion tags as structs

The backend was using strings to represent command tags and doing string
comparisons in multiple places, but that's slow and unhelpful.  Create a
new command list with a supporting structure to use instead; this is
stored in a tag-list-file that can be tailored to specific purposes with
a caller-definable C macro, similar to what we do for WAL resource
managers.  The first first such uses are a new CommandTag enum and a
CommandTagBehavior struct.

Replace numerous occurrences of char *completionTag with a
QueryCompletion struct so that the code no longer stores information
about completed queries in a cstring.  Only at the last moment, in
EndCommand(), does this get converted to a string.

EventTriggerCacheItem no longer holds an array of palloc’d tag strings
in sorted order, but rather just a Bitmapset over the CommandTags.

Author: Mark Dilger, with unsolicited help from Álvaro Herrera
Reviewed-by: John Naylor, Tom Lane
Discussion: https://postgr.es/m/[email protected]

1 files changed, 26 insertions, 6 deletions

diff --git a/src/backend/tcop/dest.c b/src/backend/tcop/dest.c
index 09c1dcbb537..7208751ec78 100644
--- a/src/backend/tcop/dest.c
+++ b/src/backend/tcop/dest.c
@@ -100,7 +100,7 @@ DestReceiver *None_Receiver = (DestReceiver *) &donothingDR;
  * ----------------
  */
 void
-BeginCommand(const char *commandTag, CommandDest dest)
+BeginCommand(CommandTag commandTag, CommandDest dest)
 {
 	/* Nothing to do at present */
 }
@@ -163,8 +163,12 @@ CreateDestReceiver(CommandDest dest)
  * ----------------
  */
 void
-EndCommand(const char *commandTag, CommandDest dest)
+EndCommand(const QueryCompletion *qc, CommandDest dest, bool force_undecorated_output)
 {
+	char		completionTag[COMPLETION_TAG_BUFSIZE];
+	CommandTag	tag;
+	const char *tagname;
+
 	switch (dest)
 	{
 		case DestRemote:
@@ -172,11 +176,27 @@ EndCommand(const char *commandTag, CommandDest dest)
 		case DestRemoteSimple:
 
 			/*
-			 * We assume the commandTag is plain ASCII and therefore requires
-			 * no encoding conversion.
+			 * We assume the tagname is plain ASCII and therefore requires no
+			 * encoding conversion.
+			 *
+			 * We no longer display LastOid, but to preserve the wire
+			 * protocol, we write InvalidOid where the LastOid used to be
+			 * written.
+			 *
+			 * All cases where LastOid was written also write nprocessed
+			 * count, so just Assert that rather than having an extra test.
 			 */
-			pq_putmessage('C', commandTag, strlen(commandTag) + 1);
-			break;
+			tag = qc->commandTag;
+			tagname = GetCommandTagName(tag);
+
+			if (command_tag_display_rowcount(tag) && !force_undecorated_output)
+				snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
+						 tag == CMDTAG_INSERT ?
+						 "%s 0 " UINT64_FORMAT : "%s " UINT64_FORMAT,
+						 tagname, qc->nprocessed);
+			else
+				snprintf(completionTag, COMPLETION_TAG_BUFSIZE, "%s", tagname);
+			pq_putmessage('C', completionTag, strlen(completionTag) + 1);
 
 		case DestNone:
 		case DestDebug: