Back out the session_start and session_end hooks feature.

It's become apparent during testing that there are problems with at
least the testing regime. I don't think we should have it without a
working test regime, and the difficulties might indicate implementation
problems anyway, so I'm backing out the whole thing until that's sorted
out.

This reverts commits 7459484 9989f92 cd8ce3a

Author: adunstan

src/backend/tcop/postgres.c

@@ -169,9 +169,6 @@ static ProcSignalReason RecoveryConflictReason;
 static MemoryContext row_description_context = NULL;
 static StringInfoData row_description_buf;
 
-/* Hook for plugins to get control at start of session */
-session_start_hook_type session_start_hook = NULL;
-
 /* ----------------------------------------------------------------
  *		decls for routines only used in this file
  * ----------------------------------------------------------------
@@ -3860,9 +3857,6 @@ PostgresMain(int argc, char *argv[],
 	if (!IsUnderPostmaster)
 		PgStartTime = GetCurrentTimestamp();
 
-	if (session_start_hook)
-		(*session_start_hook) ();
-
 	/*
 	 * POSTGRES main processing loop begins here
 	 *

src/backend/utils/init/postinit.c

@@ -76,8 +76,6 @@ static bool ThereIsAtLeastOneRole(void);
 static void process_startup_options(Port *port, bool am_superuser);
 static void process_settings(Oid databaseid, Oid roleid);
 
-/* Hook for plugins to get control at end of session */
-session_end_hook_type session_end_hook = NULL;
 
 /*** InitPostgres support ***/
 
@@ -1156,10 +1154,6 @@ ShutdownPostgres(int code, Datum arg)
 	 * them explicitly.
 	 */
 	LockReleaseAll(USER_LOCKMETHOD, true);
-
-	/* Hook at session end */
-	if (session_end_hook)
-		(*session_end_hook) ();
 }
 
 

src/include/tcop/tcopprot.h

@@ -35,13 +35,6 @@ extern PGDLLIMPORT const char *debug_query_string;
 extern int	max_stack_depth;
 extern int	PostAuthDelay;
 
-/* Hook for plugins to get control at start and end of session */
-typedef void (*session_start_hook_type) (void);
-typedef void (*session_end_hook_type) (void);
-
-extern PGDLLIMPORT session_start_hook_type session_start_hook;
-extern PGDLLIMPORT session_end_hook_type session_end_hook;
-
 /* GUC-configurable parameters */
 
 typedef enum

src/test/modules/Makefile

@@ -15,7 +15,6 @@ SUBDIRS = \
 		  test_pg_dump \
 		  test_rbtree \
 		  test_rls_hooks \
-		  test_session_hooks \
 		  test_shm_mq \
 		  worker_spi
 

src/test/modules/test_session_hooks/.gitignore

@@ -383,8 +383,6 @@ sub modulescheck
 	my $mstat = 0;
 	foreach my $module (glob("*"))
 	{
-		# test_session_hooks can't run installcheck, so skip it here
-		next if $module eq 'test_session_hooks';
 		subdircheck("$topdir/src/test/modules", $module);
 		my $status = $? >> 8;
 		$mstat ||= $status;