Remove bgw_sighup and bgw_sigterm.

Per discussion on pgsql-hackers, these aren't really needed.  Interim
versions of the background worker patch had the worker starting with
signals already unblocked, which would have made this necessary.
But the final version does not, so we don't really need it; and it
doesn't work well with the new facility for starting dynamic background
workers, so just rip it out.

Also per discussion on pgsql-hackers, back-patch this change to 9.3.
It's best to get the API break out of the way before we do an
official release of this facility, to avoid more pain for extension
authors later.

Author: robertmhaas

contrib/worker_spi/worker_spi.c

@@ -344,8 +344,6 @@ _PG_init(void)
 	worker.bgw_start_time = BgWorkerStart_RecoveryFinished;
 	worker.bgw_restart_time = BGW_NEVER_RESTART;
 	worker.bgw_main = worker_spi_main;
-	worker.bgw_sighup = NULL;
-	worker.bgw_sigterm = NULL;
 
 	/*
 	 * Now fill in worker-specific data, and do the actual registrations.
@@ -375,8 +373,6 @@ worker_spi_launch(PG_FUNCTION_ARGS)
 	worker.bgw_main = NULL;		/* new worker might not have library loaded */
 	sprintf(worker.bgw_library_name, "worker_spi");
 	sprintf(worker.bgw_function_name, "worker_spi_main");
-	worker.bgw_sighup = NULL;	/* new worker might not have library loaded */
-	worker.bgw_sigterm = NULL;	/* new worker might not have library loaded */
 	snprintf(worker.bgw_name, BGW_MAXLEN, "worker %d", i);
 	worker.bgw_main_arg = Int32GetDatum(i);
 

doc/src/sgml/bgworker.sgml

@@ -48,7 +48,6 @@
   The structure <structname>BackgroundWorker</structname> is defined thus:
 <programlisting>
 typedef void (*bgworker_main_type)(void *main_arg);
-typedef void (*bgworker_sighdlr_type)(SIGNAL_ARGS);
 typedef struct BackgroundWorker
 {
     char        bgw_name[BGW_MAXLEN];
@@ -59,8 +58,6 @@ typedef struct BackgroundWorker
     char        bgw_library_name[BGW_MAXLEN];   /* only if bgw_main is NULL */
     char        bgw_function_name[BGW_MAXLEN];  /* only if bgw_main is NULL */
     Datum       bgw_main_arg;
-    bgworker_sighdlr_type bgw_sighup;
-    bgworker_sighdlr_type bgw_sigterm;
 } BackgroundWorker;
 </programlisting>
   </para>
@@ -138,17 +135,6 @@ typedef struct BackgroundWorker
    <structfield>bgw_main</structfield> is NULL.
   </para>
 
-  <para>
-   <structfield>bgw_sighup</structfield> and <structfield>bgw_sigterm</> are
-   pointers to functions that will be installed as signal handlers for the new
-   process.  If <structfield>bgw_sighup</> is NULL, then <literal>SIG_IGN</>
-   is used; if <structfield>bgw_sigterm</> is NULL, a handler is installed that
-   will terminate the process after logging a suitable message.  These
-   fields should not be used if <structfield>bgw_main</> is NULL; instead,
-   the worker process should set its own signal handlers before calling
-   <function>BackgroundWorkerUnblockSignals()</function>.
-  </para>
-
   <para>Once running, the process can connect to a database by calling
    <function>BackgroundWorkerInitializeConnection(<parameter>char *dbname</parameter>, <parameter>char *username</parameter>)</function>.
    This allows the process to run transactions and queries using the
@@ -163,7 +149,7 @@ typedef struct BackgroundWorker
   <para>
    Signals are initially blocked when control reaches the
    <structfield>bgw_main</> function, and must be unblocked by it; this is to
-   allow the process to further customize its signal handlers, if necessary.
+   allow the process to customize its signal handlers, if necessary.
    Signals can be unblocked in the new process by calling
    <function>BackgroundWorkerUnblockSignals</> and blocked by calling
    <function>BackgroundWorkerBlockSignals</>.

src/backend/postmaster/bgworker.c

@@ -247,8 +247,6 @@ BackgroundWorkerStateChange(void)
 		rw->rw_worker.bgw_restart_time = slot->worker.bgw_restart_time;
 		rw->rw_worker.bgw_main = slot->worker.bgw_main;
 		rw->rw_worker.bgw_main_arg = slot->worker.bgw_main_arg;
-		rw->rw_worker.bgw_sighup = slot->worker.bgw_sighup;
-		rw->rw_worker.bgw_sigterm = slot->worker.bgw_sigterm;
 
 		/* Initialize postmaster bookkeeping. */
 		rw->rw_backend = NULL;

src/backend/postmaster/postmaster.c

@@ -5357,17 +5357,8 @@ do_start_bgworker(void)
 		pqsignal(SIGUSR1, bgworker_sigusr1_handler);
 		pqsignal(SIGFPE, SIG_IGN);
 	}
-
-	/* SIGTERM and SIGHUP are configurable */
-	if (worker->bgw_sigterm)
-		pqsignal(SIGTERM, worker->bgw_sigterm);
-	else
-		pqsignal(SIGTERM, bgworker_die);
-
-	if (worker->bgw_sighup)
-		pqsignal(SIGHUP, worker->bgw_sighup);
-	else
-		pqsignal(SIGHUP, SIG_IGN);
+	pqsignal(SIGTERM, bgworker_die);
+	pqsignal(SIGHUP, SIG_IGN);
 
 	pqsignal(SIGQUIT, bgworker_quickdie);
 	InitializeTimeouts();		/* establishes SIGALRM handler */

src/include/postmaster/bgworker.h

@@ -53,7 +53,6 @@
 
 
 typedef void (*bgworker_main_type) (Datum main_arg);
-typedef void (*bgworker_sighdlr_type) (SIGNAL_ARGS);
 
 /*
  * Points in time at which a bgworker can request to be started
@@ -79,8 +78,6 @@ typedef struct BackgroundWorker
 	char		bgw_library_name[BGW_MAXLEN];	/* only if bgw_main is NULL */
 	char		bgw_function_name[BGW_MAXLEN];	/* only if bgw_main is NULL */
 	Datum		bgw_main_arg;
-	bgworker_sighdlr_type bgw_sighup;
-	bgworker_sighdlr_type bgw_sigterm;
 } BackgroundWorker;
 
 /* Register a new bgworker during shared_preload_libraries */