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3a82876743
semaphore_wait and semaphore_timedwait can return KERN_ABORTED, much like POSIX semaphores can return EINTR, and need to restart their waits for correct behavior. Differential Revision: https://phabricator.services.mozilla.com/D195952
93 lines
2.9 KiB
C++
93 lines
2.9 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "CrossProcessSemaphore.h"
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#include "nsDebug.h"
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#include "nsISupportsImpl.h"
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#include <mach/mach_time.h>
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static const uint64_t kNsPerUs = 1000;
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static const uint64_t kNsPerSec = 1000000000;
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namespace mozilla {
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/* static */
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CrossProcessSemaphore* CrossProcessSemaphore::Create(const char*,
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uint32_t aInitialValue) {
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semaphore_t sem = SEMAPHORE_NULL;
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if (semaphore_create(mach_task_self(), &sem, SYNC_POLICY_FIFO,
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aInitialValue) == KERN_SUCCESS &&
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sem != SEMAPHORE_NULL) {
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return new CrossProcessSemaphore(CrossProcessSemaphoreHandle(sem));
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}
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return nullptr;
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}
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/* static */
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CrossProcessSemaphore* CrossProcessSemaphore::Create(
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CrossProcessSemaphoreHandle aHandle) {
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if (!aHandle) {
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return nullptr;
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}
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return new CrossProcessSemaphore(std::move(aHandle));
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}
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CrossProcessSemaphore::CrossProcessSemaphore(
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CrossProcessSemaphoreHandle aSemaphore)
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: mSemaphore(std::move(aSemaphore)) {
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MOZ_COUNT_CTOR(CrossProcessSemaphore);
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}
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CrossProcessSemaphore::~CrossProcessSemaphore() {
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MOZ_ASSERT(mSemaphore, "Improper construction of semaphore or double free.");
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MOZ_COUNT_DTOR(CrossProcessSemaphore);
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}
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bool CrossProcessSemaphore::Wait(const Maybe<TimeDuration>& aWaitTime) {
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MOZ_ASSERT(mSemaphore, "Improper construction of semaphore.");
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int kr = KERN_OPERATION_TIMED_OUT;
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// semaphore_(timed)wait may be interrupted by KERN_ABORTED. Carefully restart
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// the wait until it either succeeds or times out.
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if (aWaitTime.isNothing()) {
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do {
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kr = semaphore_wait(mSemaphore.get());
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} while (kr == KERN_ABORTED);
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} else {
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mach_timebase_info_data_t tb;
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if (mach_timebase_info(&tb) != KERN_SUCCESS) {
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return false;
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}
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uint64_t now = (mach_absolute_time() * tb.numer) / tb.denom;
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uint64_t deadline = now + uint64_t(kNsPerUs * aWaitTime->ToMicroseconds());
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while (now <= deadline) {
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uint64_t ns = deadline - now;
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mach_timespec_t ts;
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ts.tv_sec = ns / kNsPerSec;
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ts.tv_nsec = ns % kNsPerSec;
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kr = semaphore_timedwait(mSemaphore.get(), ts);
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if (kr != KERN_ABORTED) {
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break;
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}
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now = (mach_absolute_time() * tb.numer) / tb.denom;
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}
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}
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return kr == KERN_SUCCESS;
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}
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void CrossProcessSemaphore::Signal() {
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MOZ_ASSERT(mSemaphore, "Improper construction of semaphore.");
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semaphore_signal(mSemaphore.get());
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}
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CrossProcessSemaphoreHandle CrossProcessSemaphore::CloneHandle() {
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// Transfer the mach port backing the semaphore.
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return mozilla::RetainMachSendRight(mSemaphore.get());
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}
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void CrossProcessSemaphore::CloseHandle() {}
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} // namespace mozilla
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