mozglue/misc/RWLock_posix.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifdef XP_WIN
   8 #  error This file should only be compiled on non-Windows platforms.
   9 #endif
  10
  11 #include "mozilla/PlatformRWLock.h"
  12
  13 #include "mozilla/Assertions.h"
  14
  15 #include <errno.h>
  16
  17 // NOLINTNEXTLINE(cppcoreguidelines-pro-type-member-init)
  18 mozilla::detail::RWLockImpl::RWLockImpl() {
  19   MOZ_RELEASE_ASSERT(pthread_rwlock_init(&mRWLock, nullptr) == 0,
  20                      "pthread_rwlock_init failed");
  21 }
  22
  23 mozilla::detail::RWLockImpl::~RWLockImpl() {
  24   MOZ_RELEASE_ASSERT(pthread_rwlock_destroy(&mRWLock) == 0,
  25                      "pthread_rwlock_destroy failed");
  26 }
  27
  28 bool mozilla::detail::RWLockImpl::tryReadLock() {
  29   int rv = pthread_rwlock_tryrdlock(&mRWLock);
  30   // We allow EDEADLK here because it has been observed returned on macos when
  31   // the write lock is held by the current thread.
  32   MOZ_RELEASE_ASSERT(rv == 0 || rv == EBUSY || rv == EDEADLK,
  33                      "pthread_rwlock_tryrdlock failed");
  34   return rv == 0;
  35 }
  36
  37 void mozilla::detail::RWLockImpl::readLock() {
  38   MOZ_RELEASE_ASSERT(pthread_rwlock_rdlock(&mRWLock) == 0,
  39                      "pthread_rwlock_rdlock failed");
  40 }
  41
  42 void mozilla::detail::RWLockImpl::readUnlock() {
  43   MOZ_RELEASE_ASSERT(pthread_rwlock_unlock(&mRWLock) == 0,
  44                      "pthread_rwlock_unlock failed");
  45 }
  46
  47 bool mozilla::detail::RWLockImpl::tryWriteLock() {
  48   int rv = pthread_rwlock_trywrlock(&mRWLock);
  49   // We allow EDEADLK here because it has been observed returned on macos when
  50   // the write lock is held by the current thread.
  51   MOZ_RELEASE_ASSERT(rv == 0 || rv == EBUSY || rv == EDEADLK,
  52                      "pthread_rwlock_trywrlock failed");
  53   return rv == 0;
  54 }
  55
  56 void mozilla::detail::RWLockImpl::writeLock() {
  57   MOZ_RELEASE_ASSERT(pthread_rwlock_wrlock(&mRWLock) == 0,
  58                      "pthread_rwlock_wrlock failed");
  59 }
  60
  61 void mozilla::detail::RWLockImpl::writeUnlock() {
  62   MOZ_RELEASE_ASSERT(pthread_rwlock_unlock(&mRWLock) == 0,
  63                      "pthread_rwlock_unlock failed");
  64 }