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a4c40f140d
It works on the principle of turning sockets into non-blocking, and then emulate blocking behaviour on top of that, while allowing signals to run. Signals are now implemented using an event instead of APCs, thus getting rid of the issue of APCs not being compatible with "old style" sockets functions. It also moves the win32 specific code away from pqsignal.h/c into port/win32, and also removes the "thread style workaround" of the APC issue previously in place. In order to make things work, a few things are also changed in pgstat.c: 1) There is now a separate pipe to the collector and the bufferer. This is required because the pipe will otherwise only be signalled in one of the processes when the postmaster goes down. The MS winsock code for select() must have some kind of workaround for this behaviour, but I have found no stable way of doing that. You really are not supposed to use the same socket from more than one process (unless you use WSADuplicateSocket(), in which case the docs specifically say that only one will be flagged). 2) The check for "postmaster death" is moved into a separate select() call after the main loop. The previous behaviour select():ed on the postmaster pipe, while later explicitly saying "we do NOT check for postmaster exit inside the loop". The issue was that the code relies on the same select() call seeing both the postmaster pipe *and* the pgstat pipe go away. This does not always happen, and it appears that useing WSAEventSelect() makes it even more common that it does not. Since it's only called when the process exits, I don't think using a separate select() call will have any significant impact on how the stats collector works. Magnus Hagander
157 lines
4.1 KiB
C
157 lines
4.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* pqsignal.c
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* reliable BSD-style signal(2) routine stolen from RWW who stole it
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* from Stevens...
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*
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* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/libpq/pqsignal.c,v 1.33 2004/04/12 16:19:18 momjian Exp $
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*
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* NOTES
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* This shouldn't be in libpq, but the monitor and some other
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* things need it...
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*
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* A NOTE ABOUT SIGNAL HANDLING ACROSS THE VARIOUS PLATFORMS.
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*
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* pg_config.h defines the macro HAVE_POSIX_SIGNALS for some platforms and
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* not for others. This file and pqsignal.h use that macro to decide
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* how to handle signalling.
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*
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* signal(2) handling - this is here because it affects some of
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* the frontend commands as well as the backend server.
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*
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* Ultrix and SunOS provide BSD signal(2) semantics by default.
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*
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* SVID2 and POSIX signal(2) semantics differ from BSD signal(2)
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* semantics. We can use the POSIX sigaction(2) on systems that
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* allow us to request restartable signals (SA_RESTART).
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*
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* Some systems don't allow restartable signals at all unless we
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* link to a special BSD library.
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*
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* We devoutly hope that there aren't any systems that provide
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* neither POSIX signals nor BSD signals. The alternative
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* is to do signal-handler reinstallation, which doesn't work well
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* at all.
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* ------------------------------------------------------------------------*/
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#include "postgres.h"
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#include <signal.h>
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#include "libpq/pqsignal.h"
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/*
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* Initialize BlockSig, UnBlockSig, and AuthBlockSig.
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*
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* BlockSig is the set of signals to block when we are trying to block
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* signals. This includes all signals we normally expect to get, but NOT
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* signals that should never be turned off.
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*
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* AuthBlockSig is the set of signals to block during authentication;
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* it's essentially BlockSig minus SIGTERM, SIGQUIT, SIGALRM.
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*
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* UnBlockSig is the set of signals to block when we don't want to block
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* signals (is this ever nonzero??)
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*/
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void
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pqinitmask(void)
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{
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#ifdef HAVE_SIGPROCMASK
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sigemptyset(&UnBlockSig);
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sigfillset(&BlockSig);
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sigfillset(&AuthBlockSig);
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/*
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* Unmark those signals that should never be blocked. Some of these
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* signal names don't exist on all platforms. Most do, but might as
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* well ifdef them all for consistency...
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*/
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#ifdef SIGTRAP
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sigdelset(&BlockSig, SIGTRAP);
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sigdelset(&AuthBlockSig, SIGTRAP);
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#endif
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#ifdef SIGABRT
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sigdelset(&BlockSig, SIGABRT);
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sigdelset(&AuthBlockSig, SIGABRT);
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#endif
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#ifdef SIGILL
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sigdelset(&BlockSig, SIGILL);
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sigdelset(&AuthBlockSig, SIGILL);
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#endif
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#ifdef SIGFPE
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sigdelset(&BlockSig, SIGFPE);
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sigdelset(&AuthBlockSig, SIGFPE);
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#endif
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#ifdef SIGSEGV
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sigdelset(&BlockSig, SIGSEGV);
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sigdelset(&AuthBlockSig, SIGSEGV);
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#endif
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#ifdef SIGBUS
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sigdelset(&BlockSig, SIGBUS);
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sigdelset(&AuthBlockSig, SIGBUS);
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#endif
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#ifdef SIGSYS
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sigdelset(&BlockSig, SIGSYS);
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sigdelset(&AuthBlockSig, SIGSYS);
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#endif
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#ifdef SIGCONT
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sigdelset(&BlockSig, SIGCONT);
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sigdelset(&AuthBlockSig, SIGCONT);
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#endif
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#ifdef SIGTERM
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sigdelset(&AuthBlockSig, SIGTERM);
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#endif
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#ifdef SIGQUIT
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sigdelset(&AuthBlockSig, SIGQUIT);
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#endif
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#ifdef SIGALRM
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sigdelset(&AuthBlockSig, SIGALRM);
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#endif
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#else
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UnBlockSig = 0;
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BlockSig = sigmask(SIGHUP) | sigmask(SIGQUIT) |
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sigmask(SIGTERM) | sigmask(SIGALRM) |
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sigmask(SIGINT) | sigmask(SIGUSR1) |
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sigmask(SIGUSR2) | sigmask(SIGCHLD) |
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sigmask(SIGWINCH) | sigmask(SIGFPE);
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AuthBlockSig = sigmask(SIGHUP) |
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sigmask(SIGINT) | sigmask(SIGUSR1) |
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sigmask(SIGUSR2) | sigmask(SIGCHLD) |
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sigmask(SIGWINCH) | sigmask(SIGFPE);
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#endif
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}
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/* Win32 signal handling is in backend/port/win32/signal.c */
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#ifndef WIN32
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/*
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* Set up a signal handler
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*/
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pqsigfunc
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pqsignal(int signo, pqsigfunc func)
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{
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#if !defined(HAVE_POSIX_SIGNALS)
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return signal(signo, func);
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#else
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struct sigaction act,
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oact;
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act.sa_handler = func;
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sigemptyset(&act.sa_mask);
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act.sa_flags = 0;
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if (signo != SIGALRM)
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act.sa_flags |= SA_RESTART;
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if (sigaction(signo, &act, &oact) < 0)
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return SIG_ERR;
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return oact.sa_handler;
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#endif /* !HAVE_POSIX_SIGNALS */
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}
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#endif /* WIN32 */
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