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Combine win32 and unix latch implementations.

Browse Source 
Previously latches for windows and unix had been implemented in
different files. A later patch introduce an expanded wait
infrastructure, keeping the implementation separate would introduce too
much duplication.

This basically just moves the functions, without too much change. The
reason to keep this separate is that it allows blame to continue working
a little less badly; and to make review a tiny bit easier.

Discussion: 20160114143931.GG10941@awork2.anarazel.de
This commit is contained in:
Andres Freund 2016-03-21 09:56:39 +01:00
parent 326d73c86f
commit 72e2d21c12
10 changed files with 279 additions and 385 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
configure vendored
View File

@ -14786,13 +14786,6 @@ $as_echo "#define USE_WIN32_SHARED_MEMORY 1" >>confdefs.h
SHMEM_IMPLEMENTATION="src/backend/port/win32_shmem.c"
fi
# Select latch implementation type.
if test "$PORTNAME" != "win32"; then
LATCH_IMPLEMENTATION="src/backend/port/unix_latch.c"
else
LATCH_IMPLEMENTATION="src/backend/port/win32_latch.c"
fi
# If not set in template file, set bytes to use libc memset()
if test x"$MEMSET_LOOP_LIMIT" = x"" ; then
MEMSET_LOOP_LIMIT=1024
@ -15868,7 +15861,7 @@ fi
ac_config_files="$ac_config_files GNUmakefile src/Makefile.global"
ac_config_links="$ac_config_links src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION} src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION} src/backend/port/pg_latch.c:${LATCH_IMPLEMENTATION} src/include/dynloader.h:src/backend/port/dynloader/${template}.h src/include/pg_config_os.h:src/include/port/${template}.h src/Makefile.port:src/makefiles/Makefile.${template}"
ac_config_links="$ac_config_links src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION} src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION} src/include/dynloader.h:src/backend/port/dynloader/${template}.h src/include/pg_config_os.h:src/include/port/${template}.h src/Makefile.port:src/makefiles/Makefile.${template}"
if test "$PORTNAME" = "win32"; then
@ -16592,7 +16585,6 @@ do
"src/backend/port/dynloader.c") CONFIG_LINKS="$CONFIG_LINKS src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c" ;;
"src/backend/port/pg_sema.c") CONFIG_LINKS="$CONFIG_LINKS src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION}" ;;
"src/backend/port/pg_shmem.c") CONFIG_LINKS="$CONFIG_LINKS src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION}" ;;
"src/backend/port/pg_latch.c") CONFIG_LINKS="$CONFIG_LINKS src/backend/port/pg_latch.c:${LATCH_IMPLEMENTATION}" ;;
"src/include/dynloader.h") CONFIG_LINKS="$CONFIG_LINKS src/include/dynloader.h:src/backend/port/dynloader/${template}.h" ;;
"src/include/pg_config_os.h") CONFIG_LINKS="$CONFIG_LINKS src/include/pg_config_os.h:src/include/port/${template}.h" ;;
"src/Makefile.port") CONFIG_LINKS="$CONFIG_LINKS src/Makefile.port:src/makefiles/Makefile.${template}" ;;

8
configure.in
View File

@ -1976,13 +1976,6 @@ else
SHMEM_IMPLEMENTATION="src/backend/port/win32_shmem.c"
fi
# Select latch implementation type.
if test "$PORTNAME" != "win32"; then
LATCH_IMPLEMENTATION="src/backend/port/unix_latch.c"
else
LATCH_IMPLEMENTATION="src/backend/port/win32_latch.c"
fi
# If not set in template file, set bytes to use libc memset()
if test x"$MEMSET_LOOP_LIMIT" = x"" ; then
MEMSET_LOOP_LIMIT=1024
@ -2178,7 +2171,6 @@ AC_CONFIG_LINKS([
src/backend/port/dynloader.c:src/backend/port/dynloader/${template}.c
src/backend/port/pg_sema.c:${SEMA_IMPLEMENTATION}
src/backend/port/pg_shmem.c:${SHMEM_IMPLEMENTATION}
src/backend/port/pg_latch.c:${LATCH_IMPLEMENTATION}
src/include/dynloader.h:src/backend/port/dynloader/${template}.h
src/include/pg_config_os.h:src/include/port/${template}.h
src/Makefile.port:src/makefiles/Makefile.${template}

3
src/backend/Makefile
View File

@ -306,8 +306,7 @@ ifeq ($(PORTNAME), win32)
endif
distclean: clean
rm -f port/tas.s port/dynloader.c port/pg_sema.c port/pg_shmem.c \
port/pg_latch.c
rm -f port/tas.s port/dynloader.c port/pg_sema.c port/pg_shmem.c
maintainer-clean: distclean
rm -f bootstrap/bootparse.c \

1
src/backend/port/.gitignore vendored
View File

@ -1,5 +1,4 @@
/dynloader.c
/pg_latch.c
/pg_sema.c
/pg_shmem.c
/tas.s

2
src/backend/port/Makefile
View File

@ -21,7 +21,7 @@ subdir = src/backend/port
top_builddir = ../../..
include $(top_builddir)/src/Makefile.global
OBJS = atomics.o dynloader.o pg_sema.o pg_shmem.o pg_latch.o $(TAS)
OBJS = atomics.o dynloader.o pg_sema.o pg_shmem.o $(TAS)
ifeq ($(PORTNAME), darwin)
SUBDIRS += darwin

349
src/backend/port/win32_latch.c
View File

@ -1,349 +0,0 @@
/*-------------------------------------------------------------------------
*
* win32_latch.c
* Routines for inter-process latches
*
* See unix_latch.c for header comments for the exported functions;
* the API presented here is supposed to be the same as there.
*
* The Windows implementation uses Windows events that are inherited by
* all postmaster child processes.
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/port/win32_latch.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <unistd.h>
#include "miscadmin.h"
#include "portability/instr_time.h"
#include "postmaster/postmaster.h"
#include "storage/barrier.h"
#include "storage/latch.h"
#include "storage/pmsignal.h"
#include "storage/shmem.h"
void
InitializeLatchSupport(void)
{
/* currently, nothing to do here for Windows */
}
void
InitLatch(volatile Latch *latch)
{
latch->is_set = false;
latch->owner_pid = MyProcPid;
latch->is_shared = false;
latch->event = CreateEvent(NULL, TRUE, FALSE, NULL);
if (latch->event == NULL)
elog(ERROR, "CreateEvent failed: error code %lu", GetLastError());
}
void
InitSharedLatch(volatile Latch *latch)
{
SECURITY_ATTRIBUTES sa;
latch->is_set = false;
latch->owner_pid = 0;
latch->is_shared = true;
/*
* Set up security attributes to specify that the events are inherited.
*/
ZeroMemory(&sa, sizeof(sa));
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
latch->event = CreateEvent(&sa, TRUE, FALSE, NULL);
if (latch->event == NULL)
elog(ERROR, "CreateEvent failed: error code %lu", GetLastError());
}
void
OwnLatch(volatile Latch *latch)
{
/* Sanity checks */
Assert(latch->is_shared);
if (latch->owner_pid != 0)
elog(ERROR, "latch already owned");
latch->owner_pid = MyProcPid;
}
void
DisownLatch(volatile Latch *latch)
{
Assert(latch->is_shared);
Assert(latch->owner_pid == MyProcPid);
latch->owner_pid = 0;
}
int
WaitLatch(volatile Latch *latch, int wakeEvents, long timeout)
{
return WaitLatchOrSocket(latch, wakeEvents, PGINVALID_SOCKET, timeout);
}
int
WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
long timeout)
{
DWORD rc;
instr_time start_time,
cur_time;
long cur_timeout;
HANDLE events[4];
HANDLE latchevent;
HANDLE sockevent = WSA_INVALID_EVENT;
int numevents;
int result = 0;
int pmdeath_eventno = 0;
Assert(wakeEvents != 0); /* must have at least one wake event */
/* waiting for socket readiness without a socket indicates a bug */
if (sock == PGINVALID_SOCKET &&
(wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE)) != 0)
elog(ERROR, "cannot wait on socket event without a socket");
if ((wakeEvents & WL_LATCH_SET) && latch->owner_pid != MyProcPid)
elog(ERROR, "cannot wait on a latch owned by another process");
/*
* Initialize timeout if requested. We must record the current time so
* that we can determine the remaining timeout if WaitForMultipleObjects
* is interrupted.
*/
if (wakeEvents & WL_TIMEOUT)
{
INSTR_TIME_SET_CURRENT(start_time);
Assert(timeout >= 0 && timeout <= INT_MAX);
cur_timeout = timeout;
}
else
cur_timeout = INFINITE;
/*
* Construct an array of event handles for WaitforMultipleObjects().
*
* Note: pgwin32_signal_event should be first to ensure that it will be
* reported when multiple events are set. We want to guarantee that
* pending signals are serviced.
*/
latchevent = latch->event;
events[0] = pgwin32_signal_event;
events[1] = latchevent;
numevents = 2;
if (wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE))
{
/* Need an event object to represent events on the socket */
int flags = FD_CLOSE; /* always check for errors/EOF */
if (wakeEvents & WL_SOCKET_READABLE)
flags |= FD_READ;
if (wakeEvents & WL_SOCKET_WRITEABLE)
flags |= FD_WRITE;
sockevent = WSACreateEvent();
if (sockevent == WSA_INVALID_EVENT)
elog(ERROR, "failed to create event for socket: error code %u",
WSAGetLastError());
if (WSAEventSelect(sock, sockevent, flags) != 0)
elog(ERROR, "failed to set up event for socket: error code %u",
WSAGetLastError());
events[numevents++] = sockevent;
}
if (wakeEvents & WL_POSTMASTER_DEATH)
{
pmdeath_eventno = numevents;
events[numevents++] = PostmasterHandle;
}
/* Ensure that signals are serviced even if latch is already set */
pgwin32_dispatch_queued_signals();
do
{
/*
* The comment in unix_latch.c's equivalent to this applies here as
* well. At least after mentally replacing self-pipe with windows
* event. There's no danger of overflowing, as "Setting an event that
* is already set has no effect.".
*/
if ((wakeEvents & WL_LATCH_SET) && latch->is_set)
{
result |= WL_LATCH_SET;
/*
* Leave loop immediately, avoid blocking again. We don't attempt
* to report any other events that might also be satisfied.
*/
break;
}
rc = WaitForMultipleObjects(numevents, events, FALSE, cur_timeout);
if (rc == WAIT_FAILED)
elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
GetLastError());
else if (rc == WAIT_TIMEOUT)
{
result |= WL_TIMEOUT;
}
else if (rc == WAIT_OBJECT_0)
{
/* Service newly-arrived signals */
pgwin32_dispatch_queued_signals();
}
else if (rc == WAIT_OBJECT_0 + 1)
{
/*
* Reset the event. We'll re-check the, potentially, set latch on
* next iteration of loop, but let's not waste the cycles to
* update cur_timeout below.
*/
if (!ResetEvent(latchevent))
elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
continue;
}
else if ((wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE)) &&
rc == WAIT_OBJECT_0 + 2) /* socket is at event slot 2 */
{
WSANETWORKEVENTS resEvents;
ZeroMemory(&resEvents, sizeof(resEvents));
if (WSAEnumNetworkEvents(sock, sockevent, &resEvents) != 0)
elog(ERROR, "failed to enumerate network events: error code %u",
WSAGetLastError());
if ((wakeEvents & WL_SOCKET_READABLE) &&
(resEvents.lNetworkEvents & FD_READ))
{
result |= WL_SOCKET_READABLE;
}
if ((wakeEvents & WL_SOCKET_WRITEABLE) &&
(resEvents.lNetworkEvents & FD_WRITE))
{
result |= WL_SOCKET_WRITEABLE;
}
if (resEvents.lNetworkEvents & FD_CLOSE)
{
if (wakeEvents & WL_SOCKET_READABLE)
result |= WL_SOCKET_READABLE;
if (wakeEvents & WL_SOCKET_WRITEABLE)
result |= WL_SOCKET_WRITEABLE;
}
}
else if ((wakeEvents & WL_POSTMASTER_DEATH) &&
rc == WAIT_OBJECT_0 + pmdeath_eventno)
{
/*
* Postmaster apparently died. Since the consequences of falsely
* returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
* take the trouble to positively verify this with
* PostmasterIsAlive(), even though there is no known reason to
* think that the event could be falsely set on Windows.
*/
if (!PostmasterIsAlive())
result |= WL_POSTMASTER_DEATH;
}
else
elog(ERROR, "unexpected return code from WaitForMultipleObjects(): %lu", rc);
/* If we're not done, update cur_timeout for next iteration */
if (result == 0 && (wakeEvents & WL_TIMEOUT))
{
INSTR_TIME_SET_CURRENT(cur_time);
INSTR_TIME_SUBTRACT(cur_time, start_time);
cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
if (cur_timeout <= 0)
{
/* Timeout has expired, no need to continue looping */
result |= WL_TIMEOUT;
}
}
} while (result == 0);
/* Clean up the event object we created for the socket */
if (sockevent != WSA_INVALID_EVENT)
{
WSAEventSelect(sock, NULL, 0);
WSACloseEvent(sockevent);
}
return result;
}
/*
* The comments above the unix implementation (unix_latch.c) of this function
* apply here as well.
*/
void
SetLatch(volatile Latch *latch)
{
HANDLE handle;
/*
* The memory barrier has be to be placed here to ensure that any flag
* variables possibly changed by this process have been flushed to main
* memory, before we check/set is_set.
*/
pg_memory_barrier();
/* Quick exit if already set */
if (latch->is_set)
return;
latch->is_set = true;
/*
* See if anyone's waiting for the latch. It can be the current process if
* we're in a signal handler.
*
* Use a local variable here just in case somebody changes the event field
* concurrently (which really should not happen).
*/
handle = latch->event;
if (handle)
{
SetEvent(handle);
/*
* Note that we silently ignore any errors. We might be in a signal
* handler or other critical path where it's not safe to call elog().
*/
}
}
void
ResetLatch(volatile Latch *latch)
{
/* Only the owner should reset the latch */
Assert(latch->owner_pid == MyProcPid);
latch->is_set = false;
/*
* Ensure that the write to is_set gets flushed to main memory before we
* examine any flag variables. Otherwise a concurrent SetLatch might
* falsely conclude that it needn't signal us, even though we have missed
* seeing some flag updates that SetLatch was supposed to inform us of.
*/
pg_memory_barrier();
}

5
src/backend/storage/ipc/Makefile
View File

@ -8,7 +8,8 @@ subdir = src/backend/storage/ipc
top_builddir = ../../../..
include $(top_builddir)/src/Makefile.global
OBJS = dsm_impl.o dsm.o ipc.o ipci.o pmsignal.o procarray.o procsignal.o \
shmem.o shmqueue.o shm_mq.o shm_toc.o sinval.o sinvaladt.o standby.o
OBJS = dsm_impl.o dsm.o ipc.o ipci.o latch.o pmsignal.o procarray.o \
procsignal.o shmem.o shmqueue.o shm_mq.o shm_toc.o sinval.o \
sinvaladt.o standby.o
include $(top_srcdir)/src/backend/common.mk

282
src/backend/port/unix_latch.c → src/backend/storage/ipc/latch.c
View File

@ -1,6 +1,6 @@
/*-------------------------------------------------------------------------
*
* unix_latch.c
* latch.c
* Routines for inter-process latches
*
* The Unix implementation uses the so-called self-pipe trick to overcome
@ -22,11 +22,14 @@
* process, SIGUSR1 is sent and the signal handler in the waiting process
* writes the byte to the pipe on behalf of the signaling process.
*
* The Windows implementation uses Windows events that are inherited by
* all postmaster child processes.
*
* Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/port/unix_latch.c
* src/backend/storage/ipc/latch.c
*
*-------------------------------------------------------------------------
*/
@ -62,16 +65,20 @@
* useful to manually specify the used primitive. If desired, just add a
* define somewhere before this block.
*/
#if defined(LATCH_USE_POLL) || defined(LATCH_USE_SELECT)
#if defined(LATCH_USE_POLL) || defined(LATCH_USE_SELECT) \
|| defined(LATCH_USE_WIN32)
/* don't overwrite manual choice */
#elif defined(HAVE_POLL)
#define LATCH_USE_POLL
#elif HAVE_SYS_SELECT_H
#define LATCH_USE_SELECT
#elif WIN32
#define LATCH_USE_WIN32
#else
#error "no latch implementation available"
#endif
#ifndef WIN32
/* Are we currently in WaitLatch? The signal handler would like to know. */
static volatile sig_atomic_t waiting = false;
@ -82,6 +89,7 @@ static int selfpipe_writefd = -1;
/* Private function prototypes */
static void sendSelfPipeByte(void);
static void drainSelfPipe(void);
#endif /* WIN32 */
/*
@ -93,6 +101,7 @@ static void drainSelfPipe(void);
void
InitializeLatchSupport(void)
{
#ifndef WIN32
int pipefd[2];
Assert(selfpipe_readfd == -1);
@ -113,6 +122,9 @@ InitializeLatchSupport(void)
selfpipe_readfd = pipefd[0];
selfpipe_writefd = pipefd[1];
#else
/* currently, nothing to do here for Windows */
#endif
}
/*
@ -121,12 +133,18 @@ InitializeLatchSupport(void)
void
InitLatch(volatile Latch *latch)
{
/* Assert InitializeLatchSupport has been called in this process */
Assert(selfpipe_readfd >= 0);
latch->is_set = false;
latch->owner_pid = MyProcPid;
latch->is_shared = false;
#ifndef WIN32
/* Assert InitializeLatchSupport has been called in this process */
Assert(selfpipe_readfd >= 0);
#else
latch->event = CreateEvent(NULL, TRUE, FALSE, NULL);
if (latch->event == NULL)
elog(ERROR, "CreateEvent failed: error code %lu", GetLastError());
#endif /* WIN32 */
}
/*
@ -143,6 +161,21 @@ InitLatch(volatile Latch *latch)
void
InitSharedLatch(volatile Latch *latch)
{
#ifdef WIN32
SECURITY_ATTRIBUTES sa;
/*
* Set up security attributes to specify that the events are inherited.
*/
ZeroMemory(&sa, sizeof(sa));
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
latch->event = CreateEvent(&sa, TRUE, FALSE, NULL);
if (latch->event == NULL)
elog(ERROR, "CreateEvent failed: error code %lu", GetLastError());
#endif
latch->is_set = false;
latch->owner_pid = 0;
latch->is_shared = true;
@ -164,12 +197,14 @@ InitSharedLatch(volatile Latch *latch)
void
OwnLatch(volatile Latch *latch)
{
/* Assert InitializeLatchSupport has been called in this process */
Assert(selfpipe_readfd >= 0);
/* Sanity checks */
Assert(latch->is_shared);
/* sanity check */
#ifndef WIN32
/* Assert InitializeLatchSupport has been called in this process */
Assert(selfpipe_readfd >= 0);
#endif
if (latch->owner_pid != 0)
elog(ERROR, "latch already owned");
@ -221,6 +256,7 @@ WaitLatch(volatile Latch *latch, int wakeEvents, long timeout)
* returning the socket as readable/writable or both, depending on
* WL_SOCKET_READABLE/WL_SOCKET_WRITEABLE being specified.
*/
#ifndef LATCH_USE_WIN32
int
WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
long timeout)
@ -551,6 +587,199 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
return result;
}
#else /* LATCH_USE_WIN32 */
int
WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
long timeout)
{
DWORD rc;
instr_time start_time,
cur_time;
long cur_timeout;
HANDLE events[4];
HANDLE latchevent;
HANDLE sockevent = WSA_INVALID_EVENT;
int numevents;
int result = 0;
int pmdeath_eventno = 0;
Assert(wakeEvents != 0); /* must have at least one wake event */
/* waiting for socket readiness without a socket indicates a bug */
if (sock == PGINVALID_SOCKET &&
(wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE)) != 0)
elog(ERROR, "cannot wait on socket event without a socket");
if ((wakeEvents & WL_LATCH_SET) && latch->owner_pid != MyProcPid)
elog(ERROR, "cannot wait on a latch owned by another process");
/*
* Initialize timeout if requested. We must record the current time so
* that we can determine the remaining timeout if WaitForMultipleObjects
* is interrupted.
*/
if (wakeEvents & WL_TIMEOUT)
{
INSTR_TIME_SET_CURRENT(start_time);
Assert(timeout >= 0 && timeout <= INT_MAX);
cur_timeout = timeout;
}
else
cur_timeout = INFINITE;
/*
* Construct an array of event handles for WaitforMultipleObjects().
*
* Note: pgwin32_signal_event should be first to ensure that it will be
* reported when multiple events are set. We want to guarantee that
* pending signals are serviced.
*/
latchevent = latch->event;
events[0] = pgwin32_signal_event;
events[1] = latchevent;
numevents = 2;
if (wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE))
{
/* Need an event object to represent events on the socket */
int flags = FD_CLOSE; /* always check for errors/EOF */
if (wakeEvents & WL_SOCKET_READABLE)
flags |= FD_READ;
if (wakeEvents & WL_SOCKET_WRITEABLE)
flags |= FD_WRITE;
sockevent = WSACreateEvent();
if (sockevent == WSA_INVALID_EVENT)
elog(ERROR, "failed to create event for socket: error code %u",
WSAGetLastError());
if (WSAEventSelect(sock, sockevent, flags) != 0)
elog(ERROR, "failed to set up event for socket: error code %u",
WSAGetLastError());
events[numevents++] = sockevent;
}
if (wakeEvents & WL_POSTMASTER_DEATH)
{
pmdeath_eventno = numevents;
events[numevents++] = PostmasterHandle;
}
/* Ensure that signals are serviced even if latch is already set */
pgwin32_dispatch_queued_signals();
do
{
/*
* The comment in the unix version above applies here as well. At
* least after mentally replacing self-pipe with windows event.
* There's no danger of overflowing, as "Setting an event that is
* already set has no effect.".
*/
if ((wakeEvents & WL_LATCH_SET) && latch->is_set)
{
result |= WL_LATCH_SET;
/*
* Leave loop immediately, avoid blocking again. We don't attempt
* to report any other events that might also be satisfied.
*/
break;
}
rc = WaitForMultipleObjects(numevents, events, FALSE, cur_timeout);
if (rc == WAIT_FAILED)
elog(ERROR, "WaitForMultipleObjects() failed: error code %lu",
GetLastError());
else if (rc == WAIT_TIMEOUT)
{
result |= WL_TIMEOUT;
}
else if (rc == WAIT_OBJECT_0)
{
/* Service newly-arrived signals */
pgwin32_dispatch_queued_signals();
}
else if (rc == WAIT_OBJECT_0 + 1)
{
/*
* Reset the event. We'll re-check the, potentially, set latch on
* next iteration of loop, but let's not waste the cycles to
* update cur_timeout below.
*/
if (!ResetEvent(latchevent))
elog(ERROR, "ResetEvent failed: error code %lu", GetLastError());
continue;
}
else if ((wakeEvents & (WL_SOCKET_READABLE | WL_SOCKET_WRITEABLE)) &&
rc == WAIT_OBJECT_0 + 2) /* socket is at event slot 2 */
{
WSANETWORKEVENTS resEvents;
ZeroMemory(&resEvents, sizeof(resEvents));
if (WSAEnumNetworkEvents(sock, sockevent, &resEvents) != 0)
elog(ERROR, "failed to enumerate network events: error code %u",
WSAGetLastError());
if ((wakeEvents & WL_SOCKET_READABLE) &&
(resEvents.lNetworkEvents & FD_READ))
{
result |= WL_SOCKET_READABLE;
}
if ((wakeEvents & WL_SOCKET_WRITEABLE) &&
(resEvents.lNetworkEvents & FD_WRITE))
{
result |= WL_SOCKET_WRITEABLE;
}
if (resEvents.lNetworkEvents & FD_CLOSE)
{
if (wakeEvents & WL_SOCKET_READABLE)
result |= WL_SOCKET_READABLE;
if (wakeEvents & WL_SOCKET_WRITEABLE)
result |= WL_SOCKET_WRITEABLE;
}
}
else if ((wakeEvents & WL_POSTMASTER_DEATH) &&
rc == WAIT_OBJECT_0 + pmdeath_eventno)
{
/*
* Postmaster apparently died. Since the consequences of falsely
* returning WL_POSTMASTER_DEATH could be pretty unpleasant, we
* take the trouble to positively verify this with
* PostmasterIsAlive(), even though there is no known reason to
* think that the event could be falsely set on Windows.
*/
if (!PostmasterIsAlive())
result |= WL_POSTMASTER_DEATH;
}
else
elog(ERROR, "unexpected return code from WaitForMultipleObjects(): %lu", rc);
/* If we're not done, update cur_timeout for next iteration */
if (result == 0 && (wakeEvents & WL_TIMEOUT))
{
INSTR_TIME_SET_CURRENT(cur_time);
INSTR_TIME_SUBTRACT(cur_time, start_time);
cur_timeout = timeout - (long) INSTR_TIME_GET_MILLISEC(cur_time);
if (cur_timeout <= 0)
{
/* Timeout has expired, no need to continue looping */
result |= WL_TIMEOUT;
}
}
} while (result == 0);
/* Clean up the event object we created for the socket */
if (sockevent != WSA_INVALID_EVENT)
{
WSAEventSelect(sock, NULL, 0);
WSACloseEvent(sockevent);
}
return result;
}
#endif /* LATCH_USE_WIN32 */
/*
* Sets a latch and wakes up anyone waiting on it.
@ -567,7 +796,11 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
void
SetLatch(volatile Latch *latch)
{
#ifndef WIN32
pid_t owner_pid;
#else
HANDLE handle;
#endif
/*
* The memory barrier has be to be placed here to ensure that any flag
@ -582,6 +815,8 @@ SetLatch(volatile Latch *latch)
latch->is_set = true;
#ifndef WIN32
/*
* See if anyone's waiting for the latch. It can be the current process if
* we're in a signal handler. We use the self-pipe to wake up the select()
@ -613,6 +848,27 @@ SetLatch(volatile Latch *latch)
}
else
kill(owner_pid, SIGUSR1);
#else
/*
* See if anyone's waiting for the latch. It can be the current process if
* we're in a signal handler.
*
* Use a local variable here just in case somebody changes the event field
* concurrently (which really should not happen).
*/
handle = latch->event;
if (handle)
{
SetEvent(handle);
/*
* Note that we silently ignore any errors. We might be in a signal
* handler or other critical path where it's not safe to call elog().
*/
}
#endif
}
/*
@ -646,14 +902,17 @@ ResetLatch(volatile Latch *latch)
* NB: when calling this in a signal handler, be sure to save and restore
* errno around it.
*/
#ifndef WIN32
void
latch_sigusr1_handler(void)
{
if (waiting)
sendSelfPipeByte();
}
#endif /* !WIN32 */
/* Send one byte to the self-pipe, to wake up WaitLatch */
#ifndef WIN32
static void
sendSelfPipeByte(void)
{
@ -683,6 +942,7 @@ retry:
return;
}
}
#endif /* !WIN32 */
/*
* Read all available data from the self-pipe
@ -691,6 +951,7 @@ retry:
* return, it must reset that flag first (though ideally, this will never
* happen).
*/
#ifndef WIN32
static void
drainSelfPipe(void)
{
@ -729,3 +990,4 @@ drainSelfPipe(void)
/* else buffer wasn't big enough, so read again */
}
}
#endif /* !WIN32 */

2
src/include/storage/latch.h
View File

@ -36,7 +36,7 @@
* WaitLatch includes a provision for timeouts (which should be avoided
* when possible, as they incur extra overhead) and a provision for
* postmaster child processes to wake up immediately on postmaster death.
* See unix_latch.c for detailed specifications for the exported functions.
* See latch.c for detailed specifications for the exported functions.
*
* The correct pattern to wait for event(s) is:
*

2
src/tools/msvc/Mkvcbuild.pm
View File

@ -136,8 +136,6 @@ sub mkvcbuild
'src/backend/port/win32_sema.c');
$postgres->ReplaceFile('src/backend/port/pg_shmem.c',
'src/backend/port/win32_shmem.c');
$postgres->ReplaceFile('src/backend/port/pg_latch.c',
'src/backend/port/win32_latch.c');
$postgres->AddFiles('src/port', @pgportfiles);
$postgres->AddFiles('src/common', @pgcommonbkndfiles);
$postgres->AddDir('src/timezone');