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author Peter Eisentraut <peter@eisentraut.org>

2019年2月25日 08:24:15 +0000 (09:24 +0100)

committer Peter Eisentraut <peter@eisentraut.org>

Mon, 4 Mar 2019 10:30:41 +0000 (11:30 +0100)

This was no longer useful since the latch functions use memory
barriers already, which are also compiler barriers, and volatile does
not help with cross-process access.

Discussion: https://www.postgresql.org/message-id/flat/20190218202511.qsfpuj5sy4dbezcw%40alap3.anarazel.de#18783c27d73e9e40009c82f6e0df0974

src/backend/storage/ipc/latch.c patch | blob | blame | history

src/include/storage/latch.h patch | blob | blame | history

diff --git a/src/backend/storage/ipc/latch.c b/src/backend/storage/ipc/latch.c

index 7da337d11f0b36ca80d5576659bc7356be712c8d..59fa917ae044924ff93674a97c8403f7b396f0d4 100644 (file)

--- a/src/backend/storage/ipc/latch.c

+++ b/src/backend/storage/ipc/latch.c

@@ -225,7 +225,7 @@ InitializeLatchSupport(void)

* Initialize a process-local latch.

void

-InitLatch(volatile Latch *latch)

+InitLatch(Latch *latch)

{

latch->is_set = false;

latch->owner_pid = MyProcPid;

@@ -257,7 +257,7 @@ InitLatch(volatile Latch *latch)

* process references to postmaster-private latches or WaitEventSets.

void

-InitSharedLatch(volatile Latch *latch)

+InitSharedLatch(Latch *latch)

{

#ifdef WIN32

SECURITY_ATTRIBUTES sa;

@@ -293,7 +293,7 @@ InitSharedLatch(volatile Latch *latch)

* as shared latches use SIGUSR1 for inter-process communication.

void

-OwnLatch(volatile Latch *latch)

+OwnLatch(Latch *latch)

{

/* Sanity checks */

Assert(latch->is_shared);

@@ -313,7 +313,7 @@ OwnLatch(volatile Latch *latch)

* Disown a shared latch currently owned by the current process.

void

-DisownLatch(volatile Latch *latch)

+DisownLatch(Latch *latch)

{

Assert(latch->is_shared);

Assert(latch->owner_pid == MyProcPid);

@@ -341,7 +341,7 @@ DisownLatch(volatile Latch *latch)

* we return all of them in one call, but we will return at least one.

int

-WaitLatch(volatile Latch *latch, int wakeEvents, long timeout,

+WaitLatch(Latch *latch, int wakeEvents, long timeout,

uint32 wait_event_info)

{

return WaitLatchOrSocket(latch, wakeEvents, PGINVALID_SOCKET, timeout,

@@ -366,7 +366,7 @@ WaitLatch(volatile Latch *latch, int wakeEvents, long timeout,

* WaitEventSet instead; that's more efficient.

int

-WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,

+WaitLatchOrSocket(Latch *latch, int wakeEvents, pgsocket sock,

long timeout, uint32 wait_event_info)

{

int ret = 0;

@@ -381,7 +381,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,

if (wakeEvents & WL_LATCH_SET)

AddWaitEventToSet(set, WL_LATCH_SET, PGINVALID_SOCKET,

- (Latch *) latch, NULL);

+ latch, NULL);

/* Postmaster-managed callers must handle postmaster death somehow. */

Assert(!IsUnderPostmaster ||

@@ -433,7 +433,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,

* throwing an error is not a good idea.

void

-SetLatch(volatile Latch *latch)

+SetLatch(Latch *latch)

{

#ifndef WIN32

pid_t owner_pid;

@@ -516,7 +516,7 @@ SetLatch(volatile Latch *latch)

* the latch is set again before the WaitLatch call.

void

-ResetLatch(volatile Latch *latch)

+ResetLatch(Latch *latch)

{

/* Only the owner should reset the latch */

Assert(latch->owner_pid == MyProcPid);

diff --git a/src/include/storage/latch.h b/src/include/storage/latch.h

index 5b48709c8a424e9d091f75a49e0d585c9a48ce7b..fc995819d35235d5726d7d30a9715d38f9afe9b0 100644 (file)

--- a/src/include/storage/latch.h

+++ b/src/include/storage/latch.h

@@ -156,12 +156,12 @@ typedef struct WaitEventSet WaitEventSet;

* prototypes for functions in latch.c

extern void InitializeLatchSupport(void);

-extern void InitLatch(volatile Latch *latch);

-extern void InitSharedLatch(volatile Latch *latch);

-extern void OwnLatch(volatile Latch *latch);

-extern void DisownLatch(volatile Latch *latch);

-extern void SetLatch(volatile Latch *latch);

-extern void ResetLatch(volatile Latch *latch);

+extern void InitLatch(Latch *latch);

+extern void InitSharedLatch(Latch *latch);

+extern void OwnLatch(Latch *latch);

+extern void DisownLatch(Latch *latch);

+extern void SetLatch(Latch *latch);

+extern void ResetLatch(Latch *latch);

extern WaitEventSet *CreateWaitEventSet(MemoryContext context, int nevents);

extern void FreeWaitEventSet(WaitEventSet *set);

@@ -172,9 +172,9 @@ extern void ModifyWaitEvent(WaitEventSet *set, int pos, uint32 events, Latch *la

extern int WaitEventSetWait(WaitEventSet *set, long timeout,

WaitEvent *occurred_events, int nevents,

uint32 wait_event_info);

-extern int WaitLatch(volatile Latch *latch, int wakeEvents, long timeout,

+extern int WaitLatch(Latch *latch, int wakeEvents, long timeout,

uint32 wait_event_info);

-extern int WaitLatchOrSocket(volatile Latch *latch, int wakeEvents,

+extern int WaitLatchOrSocket(Latch *latch, int wakeEvents,

pgsocket sock, long timeout, uint32 wait_event_info);

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