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;
MutexImpl(bool recursive)26 MutexImpl::MutexImpl( bool recursive) { }
~MutexImpl()27 MutexImpl::~MutexImpl() { }
acquire()28 bool MutexImpl::acquire() { return true; }
release()29 bool MutexImpl::release() { return true; }
tryacquire()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
MutexImpl(bool recursive)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
~MutexImpl()75 MutexImpl::~MutexImpl()
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
acquire()84 MutexImpl::acquire()
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
release()94 MutexImpl::release()
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
tryacquire()104 MutexImpl::tryacquire()
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
123