tor-browser

The Tor Browser
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Mutex_posix.cpp (4200B)

      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 #include "mozilla/Assertions.h"
      8 
      9 #include <errno.h>
     10 #include <pthread.h>
     11 #include <stdio.h>
     12 
     13 #if defined(XP_DARWIN)
     14 #  include <pthread_spis.h>
     15 #endif
     16 
     17 #include "mozilla/PlatformMutex.h"
     18 #include "MutexPlatformData_posix.h"
     19 
     20 #define REPORT_PTHREADS_ERROR(result, msg) \
     21  {                                        \
     22    errno = result;                        \
     23    perror(msg);                           \
     24    MOZ_CRASH(msg);                        \
     25  }
     26 
     27 #define TRY_CALL_PTHREADS(call, msg)      \
     28  {                                       \
     29    int result = (call);                  \
     30    if (result != 0) {                    \
     31      REPORT_PTHREADS_ERROR(result, msg); \
     32    }                                     \
     33  }
     34 
     35 mozilla::detail::MutexImpl::MutexImpl() {
     36  pthread_mutexattr_t* attrp = nullptr;
     37 
     38 #if defined(DEBUG)
     39 #  define MUTEX_KIND PTHREAD_MUTEX_ERRORCHECK
     40 // Linux with glibc, FreeBSD and macOS 10.14+ support adaptive mutexes that
     41 // spin for a short number of tries before sleeping.  NSPR's locks did this,
     42 // too, and it seems like a reasonable thing to do.
     43 #elif (defined(__linux__) && defined(__GLIBC__)) || defined(__FreeBSD__)
     44 #  define MUTEX_KIND PTHREAD_MUTEX_ADAPTIVE_NP
     45 #elif defined(XP_DARWIN)
     46 #  if defined(PTHREAD_MUTEX_POLICY_FIRSTFIT_NP)
     47 #    define POLICY_KIND PTHREAD_MUTEX_POLICY_FIRSTFIT_NP
     48 #  else
     49 #    define POLICY_KIND (3)  // The definition is missing in old SDKs
     50 #  endif
     51 #endif
     52 
     53 #if defined(MUTEX_KIND) || defined(POLICY_KIND)
     54 #  define ATTR_REQUIRED
     55 #endif
     56 
     57 #if defined(ATTR_REQUIRED)
     58  pthread_mutexattr_t attr;
     59 
     60  TRY_CALL_PTHREADS(
     61      pthread_mutexattr_init(&attr),
     62      "mozilla::detail::MutexImpl::MutexImpl: pthread_mutexattr_init failed");
     63 
     64 #  if defined(MUTEX_KIND)
     65  TRY_CALL_PTHREADS(pthread_mutexattr_settype(&attr, MUTEX_KIND),
     66                    "mozilla::detail::MutexImpl::MutexImpl: "
     67                    "pthread_mutexattr_settype failed");
     68 #  elif defined(POLICY_KIND)
     69  TRY_CALL_PTHREADS(pthread_mutexattr_setpolicy_np(&attr, POLICY_KIND),
     70                    "mozilla::detail::MutexImpl::MutexImpl: "
     71                    "pthread_mutexattr_setpolicy_np failed");
     72 #  endif
     73  attrp = &attr;
     74 #endif
     75 
     76  TRY_CALL_PTHREADS(
     77      pthread_mutex_init(&platformData()->ptMutex, attrp),
     78      "mozilla::detail::MutexImpl::MutexImpl: pthread_mutex_init failed");
     79 
     80 #if defined(ATTR_REQUIRED)
     81  TRY_CALL_PTHREADS(pthread_mutexattr_destroy(&attr),
     82                    "mozilla::detail::MutexImpl::MutexImpl: "
     83                    "pthread_mutexattr_destroy failed");
     84 #endif
     85 }
     86 
     87 mozilla::detail::MutexImpl::~MutexImpl() {
     88  TRY_CALL_PTHREADS(
     89      pthread_mutex_destroy(&platformData()->ptMutex),
     90      "mozilla::detail::MutexImpl::~MutexImpl: pthread_mutex_destroy failed");
     91 }
     92 
     93 inline void mozilla::detail::MutexImpl::mutexLock() {
     94  TRY_CALL_PTHREADS(
     95      pthread_mutex_lock(&platformData()->ptMutex),
     96      "mozilla::detail::MutexImpl::mutexLock: pthread_mutex_lock failed");
     97 }
     98 
     99 bool mozilla::detail::MutexImpl::tryLock() { return mutexTryLock(); }
    100 
    101 bool mozilla::detail::MutexImpl::mutexTryLock() {
    102  int result = pthread_mutex_trylock(&platformData()->ptMutex);
    103  if (result == 0) {
    104    return true;
    105  }
    106 
    107  if (result == EBUSY) {
    108    return false;
    109  }
    110 
    111  REPORT_PTHREADS_ERROR(
    112      result,
    113      "mozilla::detail::MutexImpl::mutexTryLock: pthread_mutex_trylock failed");
    114 }
    115 
    116 void mozilla::detail::MutexImpl::lock() { mutexLock(); }
    117 
    118 void mozilla::detail::MutexImpl::unlock() {
    119  TRY_CALL_PTHREADS(
    120      pthread_mutex_unlock(&platformData()->ptMutex),
    121      "mozilla::detail::MutexImpl::unlock: pthread_mutex_unlock failed");
    122 }
    123 
    124 #undef TRY_CALL_PTHREADS
    125 
    126 mozilla::detail::MutexImpl::PlatformData*
    127 mozilla::detail::MutexImpl::platformData() {
    128  static_assert(sizeof(platformData_) >= sizeof(PlatformData),
    129                "platformData_ is too small");
    130  return reinterpret_cast<PlatformData*>(platformData_);
    131 }