lib/Support/Mutex.cpp

   1 //===- Mutex.cpp - Mutual Exclusion Lock ------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the llvm::sys::Mutex class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/Support/Mutex.h"
  14 #include "llvm/Config/config.h"
  15 #include "llvm/Support/ErrorHandling.h"
  16
  17 //===----------------------------------------------------------------------===//
  18 //=== WARNING: Implementation here must contain only TRULY operating system
  19 //===          independent code.
  20 //===----------------------------------------------------------------------===//
  21
  22 #if !defined(LLVM_ENABLE_THREADS) || LLVM_ENABLE_THREADS == 0
  23 // Define all methods as no-ops if threading is explicitly disabled
  24 namespace llvm {
  25 using namespace sys;
  26 MutexImpl::MutexImpl( bool recursive) { }
  27 MutexImpl::~MutexImpl() { }
  28 bool MutexImpl::acquire() { return true; }
  29 bool MutexImpl::release() { return true; }
  30 bool MutexImpl::tryacquire() { return true; }
  31 }
  32 #else
  33
  34 #if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_MUTEX_LOCK)
  35
  36 #include <cassert>
  37 #include <pthread.h>
  38 #include <stdlib.h>
  39
  40 namespace llvm {
  41 using namespace sys;
  42
  43 // Construct a Mutex using pthread calls
  44 MutexImpl::MutexImpl( bool recursive)
  45   : data_(nullptr)
  46 {
  47   // Declare the pthread_mutex data structures
  48   pthread_mutex_t* mutex =
  49     static_cast<pthread_mutex_t*>(safe_malloc(sizeof(pthread_mutex_t)));
  50
  51   pthread_mutexattr_t attr;
  52
  53   // Initialize the mutex attributes
  54   int errorcode = pthread_mutexattr_init(&attr);
  55   assert(errorcode == 0); (void)errorcode;
  56
  57   // Initialize the mutex as a recursive mutex, if requested, or normal
  58   // otherwise.
  59   int kind = ( recursive  ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL );
  60   errorcode = pthread_mutexattr_settype(&attr, kind);
  61   assert(errorcode == 0);
  62
  63   // Initialize the mutex
  64   errorcode = pthread_mutex_init(mutex, &attr);
  65   assert(errorcode == 0);
  66
  67   // Destroy the attributes
  68   errorcode = pthread_mutexattr_destroy(&attr);
  69   assert(errorcode == 0);
  70
  71   // Assign the data member
  72   data_ = mutex;
  73 }
  74
  75 // Destruct a Mutex
  76 MutexImpl::~MutexImpl()
  77 {
  78   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
  79   assert(mutex != nullptr);
  80   pthread_mutex_destroy(mutex);
  81   free(mutex);
  82 }
  83
  84 bool
  85 MutexImpl::acquire()
  86 {
  87   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
  88   assert(mutex != nullptr);
  89
  90   int errorcode = pthread_mutex_lock(mutex);
  91   return errorcode == 0;
  92 }
  93
  94 bool
  95 MutexImpl::release()
  96 {
  97   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
  98   assert(mutex != nullptr);
  99
 100   int errorcode = pthread_mutex_unlock(mutex);
 101   return errorcode == 0;
 102 }
 103
 104 bool
 105 MutexImpl::tryacquire()
 106 {
 107   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
 108   assert(mutex != nullptr);
 109
 110   int errorcode = pthread_mutex_trylock(mutex);
 111   return errorcode == 0;
 112 }
 113
 114 }
 115
 116 #elif defined(LLVM_ON_UNIX)
 117 #include "Unix/Mutex.inc"
 118 #elif defined( _WIN32)
 119 #include "Windows/Mutex.inc"
 120 #else
 121 #warning Neither LLVM_ON_UNIX nor _WIN32 was set in Support/Mutex.cpp
 122 #endif
 123 #endif