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/Support/Mutex.h"
15 #include "llvm/Support/ErrorHandling.h"
16 #include "llvm/Config/config.h"
17 
18 //===----------------------------------------------------------------------===//
19 //=== WARNING: Implementation here must contain only TRULY operating system
20 //===          independent code.
21 //===----------------------------------------------------------------------===//
22 
23 #if !defined(LLVM_ENABLE_THREADS) || LLVM_ENABLE_THREADS == 0
24 // Define all methods as no-ops if threading is explicitly disabled
25 namespace llvm {
26 using namespace sys;
27 MutexImpl::MutexImpl( bool recursive) { }
28 MutexImpl::~MutexImpl() { }
29 bool MutexImpl::acquire() { return true; }
30 bool MutexImpl::release() { return true; }
31 bool MutexImpl::tryacquire() { return true; }
32 }
33 #else
34 
35 #if defined(HAVE_PTHREAD_H) && defined(HAVE_PTHREAD_MUTEX_LOCK)
36 
37 #include <cassert>
38 #include <pthread.h>
39 #include <stdlib.h>
40 
41 namespace llvm {
42 using namespace sys;
43 
44 // Construct a Mutex using pthread calls
45 MutexImpl::MutexImpl( bool recursive)
46   : data_(nullptr)
47 {
48   // Declare the pthread_mutex data structures
49   pthread_mutex_t* mutex =
50     static_cast<pthread_mutex_t*>(malloc(sizeof(pthread_mutex_t)));
51 
52   if (mutex == nullptr)
53     report_bad_alloc_error("Mutex allocation failed");
54 
55   pthread_mutexattr_t attr;
56 
57   // Initialize the mutex attributes
58   int errorcode = pthread_mutexattr_init(&attr);
59   assert(errorcode == 0); (void)errorcode;
60 
61   // Initialize the mutex as a recursive mutex, if requested, or normal
62   // otherwise.
63   int kind = ( recursive  ? PTHREAD_MUTEX_RECURSIVE : PTHREAD_MUTEX_NORMAL );
64   errorcode = pthread_mutexattr_settype(&attr, kind);
65   assert(errorcode == 0);
66 
67   // Initialize the mutex
68   errorcode = pthread_mutex_init(mutex, &attr);
69   assert(errorcode == 0);
70 
71   // Destroy the attributes
72   errorcode = pthread_mutexattr_destroy(&attr);
73   assert(errorcode == 0);
74 
75   // Assign the data member
76   data_ = mutex;
77 }
78 
79 // Destruct a Mutex
80 MutexImpl::~MutexImpl()
81 {
82   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
83   assert(mutex != nullptr);
84   pthread_mutex_destroy(mutex);
85   free(mutex);
86 }
87 
88 bool
89 MutexImpl::acquire()
90 {
91   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
92   assert(mutex != nullptr);
93 
94   int errorcode = pthread_mutex_lock(mutex);
95   return errorcode == 0;
96 }
97 
98 bool
99 MutexImpl::release()
100 {
101   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
102   assert(mutex != nullptr);
103 
104   int errorcode = pthread_mutex_unlock(mutex);
105   return errorcode == 0;
106 }
107 
108 bool
109 MutexImpl::tryacquire()
110 {
111   pthread_mutex_t* mutex = static_cast<pthread_mutex_t*>(data_);
112   assert(mutex != nullptr);
113 
114   int errorcode = pthread_mutex_trylock(mutex);
115   return errorcode == 0;
116 }
117 
118 }
119 
120 #elif defined(LLVM_ON_UNIX)
121 #include "Unix/Mutex.inc"
122 #elif defined( LLVM_ON_WIN32)
123 #include "Windows/Mutex.inc"
124 #else
125 #warning Neither LLVM_ON_UNIX nor LLVM_ON_WIN32 was set in Support/Mutex.cpp
126 #endif
127 #endif
128