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Unify SIGHUP handling between normal and walsender backends.

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Because walsender and normal backends share the same main loop it's
problematic to have two different flag variables, set in signal
handlers, indicating a pending configuration reload.  Only certain
walsender commands reach code paths checking for the
variable (START_[LOGICAL_]REPLICATION, CREATE_REPLICATION_SLOT
... LOGICAL, notably not base backups).

This is a bug present since the introduction of walsender, but has
gotten worse in releases since then which allow walsender to do more.

A later patch, not slated for v10, will similarly unify SIGHUP
handling in other types of processes as well.

Author: Petr Jelinek, Andres Freund
Reviewed-By: Michael Paquier
Discussion: https://postgr.es/m/20170423235941.qosiuoyqprq4nu7v@alap3.anarazel.de
Backpatch: 9.2-, bug is present since 9.0
This commit is contained in:
Andres Freund
2017-06-05 18:53:41 -07:00
parent 862204aace
commit b8bd32a51f
4 changed files with 27 additions and 38 deletions
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30
src/backend/tcop/postgres.c
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@ -121,13 +121,6 @@ char *stack_base_ptr = NULL;
char *register_stack_base_ptr = NULL;
#endif
/*
* Flag to mark SIGHUP. Whenever the main loop comes around it
* will reread the configuration file. (Better than doing the
* reading in the signal handler, ey?)
*/
static volatile sig_atomic_t got_SIGHUP = false;
/*
* Flag to keep track of whether we have started a transaction.
* For extended query protocol this has to be remembered across messages.
@ -186,7 +179,6 @@ static bool IsTransactionExitStmt(Node *parsetree);
static bool IsTransactionExitStmtList(List *parseTrees);
static bool IsTransactionStmtList(List *parseTrees);
static void drop_unnamed_stmt(void);
static void SigHupHandler(SIGNAL_ARGS);
static void log_disconnections(int code, Datum arg);
@ -2689,13 +2681,19 @@ FloatExceptionHandler(SIGNAL_ARGS)
"invalid operation, such as division by zero.")));
}
/* SIGHUP: set flag to re-read config file at next convenient time */
static void
SigHupHandler(SIGNAL_ARGS)
/*
* SIGHUP: set flag to re-read config file at next convenient time.
*
* Sets the ConfigReloadPending flag, which should be checked at convenient
* places inside main loops. (Better than doing the reading in the signal
* handler, ey?)
*/
void
PostgresSigHupHandler(SIGNAL_ARGS)
{
int save_errno = errno;
got_SIGHUP = true;
ConfigReloadPending = true;
SetLatch(MyLatch);
errno = save_errno;
@ -3633,8 +3631,8 @@ PostgresMain(int argc, char *argv[],
WalSndSignals();
else
{
pqsignal(SIGHUP, SigHupHandler); /* set flag to read config
* file */
pqsignal(SIGHUP, PostgresSigHupHandler); /* set flag to read config
* file */
pqsignal(SIGINT, StatementCancelHandler); /* cancel current query */
pqsignal(SIGTERM, die); /* cancel current query and exit */
@ -4045,9 +4043,9 @@ PostgresMain(int argc, char *argv[],
* (6) check for any other interesting events that happened while we
* slept.
*/
if (got_SIGHUP)
if (ConfigReloadPending)
{
got_SIGHUP = false;
ConfigReloadPending = false;
ProcessConfigFile(PGC_SIGHUP);
}