From d114c19ba15e6e2e36d1e35ad187b7208107679e Mon Sep 17 00:00:00 2001
From: Tatsuo Ishii <ishii@postgresql.org>
Date: Sun, 10 Sep 2017 18:06:47 +0900
Subject: [PATCH] Add debugging aid to check pending message and backend
 response.

New function pool_check_pending_message_and_reply() added.  If pending
message kind and backend reply message kind is not inconsistent, it
prints a debug message. Currently the only client of the function is
read_kind_from_backend().
---
 src/context/pool_session_context.c         | 39 ++++++++++++++++++++++
 src/include/context/pool_session_context.h |  3 +-
 src/protocol/pool_process_query.c          |  1 +
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/context/pool_session_context.c b/src/context/pool_session_context.c
index f0afe12e8..5d4e2cbe1 100644
--- a/src/context/pool_session_context.c
+++ b/src/context/pool_session_context.c
@@ -1397,6 +1397,45 @@ const char *pool_pending_message_type_to_string(POOL_MESSAGE_TYPE type)
 	return pending_msg_string[type];
 }
 
+/*
+ * Check consistency the message type and backend message kind.
+ * This function is intended to be used for debugging.
+ */
+void pool_check_pending_message_and_reply(POOL_MESSAGE_TYPE type, char kind)
+{
+	/* 
+	 * Backend response message sorted by POOL_MESSAGE_TYPE
+	 */
+	static char backend_response_kind[] = {
+		'1',	/* POOL_PARSE, parse complete */
+		'2',	/* POOL_BIND, bind complete */
+		'*',	/* POOL_EXECUTE, skip checking */
+		'*',	/* POOL_DESCRIBE, skip checking */
+		'3',	/* POOL_CLOSE, close complete */
+		'Z'	/* POOL_SYNC, ready for query */
+	};
+
+	if (type < POOL_PARSE || type > POOL_SYNC)
+	{
+		ereport(DEBUG1,
+				(errmsg("pool_check_pending_message_and_reply: type out of range: %d", type)));
+		return;
+	}
+
+	if (backend_response_kind[type] == '*')
+	{
+		return;
+	}
+
+	if (backend_response_kind[type] != kind)
+	{
+		ereport(DEBUG1,
+				(errmsg("pool_check_pending_message_and_reply: type: %s but is kind: %c",
+						pool_pending_message_type_to_string(type), kind)));
+	}
+	return;
+}
+
 /*
  * Find the latest pending message having specified query context.  The
  * returned message is a pointer to the message list. So do not free it using
diff --git a/src/include/context/pool_session_context.h b/src/include/context/pool_session_context.h
index ec7a3c335..2956b1d15 100644
--- a/src/include/context/pool_session_context.h
+++ b/src/include/context/pool_session_context.h
@@ -109,7 +109,7 @@ typedef struct {
  */
 
 typedef enum {
-	POOL_PARSE,
+	POOL_PARSE = 0,
 	POOL_BIND,
 	POOL_EXECUTE,
 	POOL_DESCRIBE,
@@ -301,6 +301,7 @@ extern void pool_pending_message_set_previous_message(POOL_PENDING_MESSAGE *mess
 extern POOL_PENDING_MESSAGE *pool_pending_message_get_previous_message(void);
 extern bool pool_pending_message_exists(void);
 extern const char *pool_pending_message_type_to_string(POOL_MESSAGE_TYPE type);
+extern void pool_check_pending_message_and_reply(POOL_MESSAGE_TYPE type, char kind);
 extern POOL_PENDING_MESSAGE *pool_pending_message_find_lastest_by_query_context(POOL_QUERY_CONTEXT *qc);
 extern void dump_pending_message(void);
 extern void pool_set_major_version(int major);
diff --git a/src/protocol/pool_process_query.c b/src/protocol/pool_process_query.c
index 9631a5fb8..50f690c63 100644
--- a/src/protocol/pool_process_query.c
+++ b/src/protocol/pool_process_query.c
@@ -3641,6 +3641,7 @@ void read_kind_from_backend(POOL_CONNECTION *frontend, POOL_CONNECTION_POOL *bac
 				ereport(DEBUG1,
 						(errmsg("read_kind_from_backend: pending message was pulled out")));
 				pending_message = pool_pending_message_pull_out();
+				pool_check_pending_message_and_reply(msg->type, *decided_kind);
 			}
 
 			if (pending_message)
-- 
2.39.5