@ -614,9 +614,9 @@ PostmasterMain(int argc, char *argv[])
* In the postmaster , we want to install non - ignored handlers * without *
* SA_RESTART . This is because they ' ll be blocked at all times except
* when ServerLoop is waiting for something to happen , and during that
* window , we want signals to exit the p select( 2 ) wait so that ServerLoop
* window , we want signals to exit the select ( 2 ) wait so that ServerLoop
* can respond if anything interesting happened . On some platforms ,
* signals marked SA_RESTART would not cause the p select( ) wait to end .
* signals marked SA_RESTART would not cause the select ( ) wait to end .
* Child processes will generally want SA_RESTART , but we expect them to
* set up their own handlers before unblocking signals .
*
@ -1670,8 +1670,6 @@ ServerLoop(void)
for ( ; ; )
{
fd_set rmask ;
fd_set * rmask_p ;
struct timeval timeout ;
int selres ;
time_t now ;
@ -1681,64 +1679,37 @@ ServerLoop(void)
* We block all signals except while sleeping . That makes it safe for
* signal handlers , which again block all signals while executing , to
* do nontrivial work .
*
* If we are in PM_WAIT_DEAD_END state , then we don ' t want to accept
* any new connections , so we don ' t call select ( ) , and just sleep .
*/
memcpy ( ( char * ) & rmask , ( char * ) & readmask , sizeof ( fd_set ) ) ;
if ( pmState = = PM_WAIT_DEAD_END )
{
/*
* If we are in PM_WAIT_DEAD_END state , then we don ' t want to
* accept any new connections , so pass a null rmask .
*/
rmask_p = NULL ;
timeout . tv_sec = 0 ;
timeout . tv_usec = 100000 ; /* 100 msec seems reasonable */
PG_SETMASK ( & UnBlockSig ) ;
pg_usleep ( 100000L ) ; /* 100 msec seems reasonable */
selres = 0 ;
PG_SETMASK ( & BlockSig ) ;
}
else
{
/* Normal case: check sockets, and compute a suitable timeout */
memcpy ( & rmask , & readmask , sizeof ( fd_set ) ) ;
rmask_p = & rmask ;
/* must set timeout each time; some OSes change it! */
struct timeval timeout ;
/* Needs to run with blocked signals! */
DetermineSleepTime ( & timeout ) ;
}
/*
* We prefer to wait with pselect ( 2 ) if available , as using that ,
* together with * not * using SA_RESTART for signals , guarantees that
* we will get kicked off the wait if a signal occurs .
*
* If we lack pselect ( 2 ) , fake it with select ( 2 ) . This has a race
* condition : a signal that was already pending will be delivered
* before we reach the select ( ) , and therefore the select ( ) will wait ,
* even though we might wish to do something in response . Therefore ,
* beware of putting any time - critical signal response logic into
* ServerLoop rather than into the signal handler itself . It will run
* eventually , but maybe not till after a timeout delay .
*
* Some implementations of pselect ( ) are reportedly not atomic , making
* the first alternative here functionally equivalent to the second .
* Not much we can do about that though .
*/
{
# ifdef HAVE_PSELECT
/* pselect uses a randomly different timeout API, sigh */
struct timespec ptimeout ;
ptimeout . tv_sec = timeout . tv_sec ;
ptimeout . tv_nsec = timeout . tv_usec * 1000 ;
selres = pselect ( nSockets , rmask_p , NULL , NULL ,
& ptimeout , & UnBlockSig ) ;
# else
PG_SETMASK ( & UnBlockSig ) ;
selres = select ( nSockets , rmask_p , NULL , NULL , & timeout ) ;
selres = select ( nSockets , & rmask , NULL , NULL , & timeout ) ;
PG_SETMASK ( & BlockSig ) ;
# endif
}
/* Now check the select()/pselect() result */
/* Now check the select() result */
if ( selres < 0 )
{
if ( errno ! = EINTR & & errno ! = EWOULDBLOCK )
Tom Lane
9 years ago