mozglue/misc/Mutex_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 #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 }