002_session_end_hook.patch

diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index b8d860e..8b5e408 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -160,6 +160,9 @@ static bool RecoveryConflictPending = false;
 static bool RecoveryConflictRetryable = true;
 static ProcSignalReason RecoveryConflictReason;
 
+/* Hook for plugins to get control at end of session */
+session_end_hook_type session_end_hook = NULL;
+
 /* ----------------------------------------------------------------
  *		decls for routines only used in this file
  * ----------------------------------------------------------------
@@ -182,6 +185,7 @@ static bool IsTransactionExitStmtList(List *pstmts);
 static bool IsTransactionStmtList(List *pstmts);
 static void drop_unnamed_stmt(void);
 static void log_disconnections(int code, Datum arg);
+static void do_session_end_hook(int code, Datum arg);
 
 
 /* ----------------------------------------------------------------
@@ -3809,6 +3813,12 @@ PostgresMain(int argc, char *argv[],
 		PgStartTime = GetCurrentTimestamp();
 
 	/*
+	 * Setup handler to session end hook
+	 */
+	if (IsUnderPostmaster)
+		on_proc_exit(do_session_end_hook, 0);
+
+	/*
 	 * POSTGRES main processing loop begins here
 	 *
 	 * If an exception is encountered, processing resumes here so we abort the
@@ -4514,3 +4524,15 @@ log_disconnections(int code, Datum arg)
 					port->user_name, port->database_name, port->remote_host,
 					port->remote_port[0] ? " port=" : "", port->remote_port)));
 }
+
+/*
+ * on_proc_exit handler to call session end hook
+ */
+static void
+do_session_end_hook(int code, Datum arg)
+{
+	Port	   *port = MyProcPort;
+
+	if (session_end_hook)
+		(*session_end_hook) (port->database_name, port->user_name);
+}
diff --git a/src/include/tcop/tcopprot.h b/src/include/tcop/tcopprot.h
index f8c535c..6d38d0b 100644
--- a/src/include/tcop/tcopprot.h
+++ b/src/include/tcop/tcopprot.h
@@ -35,6 +35,11 @@ extern PGDLLIMPORT const char *debug_query_string;
 extern int	max_stack_depth;
 extern int	PostAuthDelay;
 
+/* Hook for plugins to get control at end of session */
+typedef void (*session_end_hook_type) (const char *dbname,
+									   const char *username);
+extern PGDLLIMPORT session_end_hook_type session_end_hook;
+
 /* GUC-configurable parameters */
 
 typedef enum