LLVM  3.7.0
Mutex.cpp
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1 //===- Mutex.cpp - Mutual Exclusion Lock ------------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the llvm::sys::Mutex class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "llvm/Config/config.h"
15 #include "llvm/Support/Mutex.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) { }
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*>(malloc(sizeof(pthread_mutex_t)));
50  pthread_mutexattr_t attr;
51 
52  // Initialize the mutex attributes
53  int errorcode = pthread_mutexattr_init(&attr);
54  assert(errorcode == 0); (void)errorcode;
55 
56  // Initialize the mutex as a recursive mutex, if requested, or normal
57  // otherwise.
58  int kind = ( recursive ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL );
59  errorcode = pthread_mutexattr_settype(&attr, kind);
60  assert(errorcode == 0);
61 
62  // Initialize the mutex
63  errorcode = pthread_mutex_init(mutex, &attr);
64  assert(errorcode == 0);
65 
66  // Destroy the attributes
67  errorcode = pthread_mutexattr_destroy(&attr);
68  assert(errorcode == 0);
69 
70  // Assign the data member
71  data_ = mutex;
72 }
73 
74 // Destruct a Mutex
76 {
77  pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
78  assert(mutex != nullptr);
79  pthread_mutex_destroy(mutex);
80  free(mutex);
81 }
82 
83 bool
85 {
86  pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
87  assert(mutex != nullptr);
88 
89  int errorcode = pthread_mutex_lock(mutex);
90  return errorcode == 0;
91 }
92 
93 bool
95 {
96  pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
97  assert(mutex != nullptr);
98 
99  int errorcode = pthread_mutex_unlock(mutex);
100  return errorcode == 0;
101 }
102 
103 bool
105 {
106  pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
107  assert(mutex != nullptr);
108 
109  int errorcode = pthread_mutex_trylock(mutex);
110  return errorcode == 0;
111 }
112 
113 }
114 
115 #elif defined(LLVM_ON_UNIX)
116 #include "Unix/Mutex.inc"
117 #elif defined( LLVM_ON_WIN32)
118 #include "Windows/Mutex.inc"
119 #else
120 #warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in Support/Mutex.cpp
121 #endif
122 #endif
bool acquire()
Attempts to unconditionally acquire the lock.
Definition: Mutex.cpp:84
bool release()
Attempts to release the lock.
Definition: Mutex.cpp:94
MutexImpl(bool recursive=true)
Initializes the lock but doesn't acquire it.
Definition: Mutex.cpp:44
~MutexImpl()
Releases and removes the lock.
Definition: Mutex.cpp:75
bool tryacquire()
Attempts to acquire the lock without blocking.
Definition: Mutex.cpp:104