1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/synchronization/condition_variable.h"
6
7 #include <errno.h>
8 #include <stdint.h>
9 #include <sys/time.h>
10
11 #include "base/synchronization/lock.h"
12 #include "base/threading/thread_restrictions.h"
13 #include "base/time/time.h"
14 #include "build/build_config.h"
15
16 namespace base {
17
ConditionVariable(Lock * user_lock)18 ConditionVariable::ConditionVariable(Lock* user_lock)
19 : user_mutex_(user_lock->lock_.native_handle())
20 #if DCHECK_IS_ON()
21 , user_lock_(user_lock)
22 #endif
23 {
24 int rv = 0;
25 // http://crbug.com/293736
26 // NaCl doesn't support monotonic clock based absolute deadlines.
27 // On older Android platform versions, it's supported through the
28 // non-standard pthread_cond_timedwait_monotonic_np. Newer platform
29 // versions have pthread_condattr_setclock.
30 // Mac can use relative time deadlines.
31 #if !defined(OS_MACOSX) && !defined(OS_NACL) && \
32 !(defined(OS_ANDROID) && defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC))
33 pthread_condattr_t attrs;
34 rv = pthread_condattr_init(&attrs);
35 DCHECK_EQ(0, rv);
36 pthread_condattr_setclock(&attrs, CLOCK_MONOTONIC);
37 rv = pthread_cond_init(&condition_, &attrs);
38 pthread_condattr_destroy(&attrs);
39 #else
40 rv = pthread_cond_init(&condition_, NULL);
41 #endif
42 DCHECK_EQ(0, rv);
43 }
44
~ConditionVariable()45 ConditionVariable::~ConditionVariable() {
46 #if defined(OS_MACOSX)
47 // This hack is necessary to avoid a fatal pthreads subsystem bug in the
48 // Darwin kernel. http://crbug.com/517681.
49 {
50 base::Lock lock;
51 base::AutoLock l(lock);
52 struct timespec ts;
53 ts.tv_sec = 0;
54 ts.tv_nsec = 1;
55 pthread_cond_timedwait_relative_np(&condition_, lock.lock_.native_handle(),
56 &ts);
57 }
58 #endif
59
60 int rv = pthread_cond_destroy(&condition_);
61 DCHECK_EQ(0, rv);
62 }
63
Wait()64 void ConditionVariable::Wait() {
65 base::ThreadRestrictions::AssertWaitAllowed();
66 #if DCHECK_IS_ON()
67 user_lock_->CheckHeldAndUnmark();
68 #endif
69 int rv = pthread_cond_wait(&condition_, user_mutex_);
70 DCHECK_EQ(0, rv);
71 #if DCHECK_IS_ON()
72 user_lock_->CheckUnheldAndMark();
73 #endif
74 }
75
TimedWait(const TimeDelta & max_time)76 void ConditionVariable::TimedWait(const TimeDelta& max_time) {
77 base::ThreadRestrictions::AssertWaitAllowed();
78 int64_t usecs = max_time.InMicroseconds();
79 struct timespec relative_time;
80 relative_time.tv_sec = usecs / Time::kMicrosecondsPerSecond;
81 relative_time.tv_nsec =
82 (usecs % Time::kMicrosecondsPerSecond) * Time::kNanosecondsPerMicrosecond;
83
84 #if DCHECK_IS_ON()
85 user_lock_->CheckHeldAndUnmark();
86 #endif
87
88 #if defined(OS_MACOSX)
89 int rv = pthread_cond_timedwait_relative_np(
90 &condition_, user_mutex_, &relative_time);
91 #else
92 // The timeout argument to pthread_cond_timedwait is in absolute time.
93 struct timespec absolute_time;
94 #if defined(OS_NACL)
95 // See comment in constructor for why this is different in NaCl.
96 struct timeval now;
97 gettimeofday(&now, NULL);
98 absolute_time.tv_sec = now.tv_sec;
99 absolute_time.tv_nsec = now.tv_usec * Time::kNanosecondsPerMicrosecond;
100 #else
101 struct timespec now;
102 clock_gettime(CLOCK_MONOTONIC, &now);
103 absolute_time.tv_sec = now.tv_sec;
104 absolute_time.tv_nsec = now.tv_nsec;
105 #endif
106
107 absolute_time.tv_sec += relative_time.tv_sec;
108 absolute_time.tv_nsec += relative_time.tv_nsec;
109 absolute_time.tv_sec += absolute_time.tv_nsec / Time::kNanosecondsPerSecond;
110 absolute_time.tv_nsec %= Time::kNanosecondsPerSecond;
111 DCHECK_GE(absolute_time.tv_sec, now.tv_sec); // Overflow paranoia
112
113 #if defined(OS_ANDROID) && defined(HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC)
114 int rv = pthread_cond_timedwait_monotonic_np(
115 &condition_, user_mutex_, &absolute_time);
116 #else
117 int rv = pthread_cond_timedwait(&condition_, user_mutex_, &absolute_time);
118 #endif // OS_ANDROID && HAVE_PTHREAD_COND_TIMEDWAIT_MONOTONIC
119 #endif // OS_MACOSX
120
121 DCHECK(rv == 0 || rv == ETIMEDOUT);
122 #if DCHECK_IS_ON()
123 user_lock_->CheckUnheldAndMark();
124 #endif
125 }
126
Broadcast()127 void ConditionVariable::Broadcast() {
128 int rv = pthread_cond_broadcast(&condition_);
129 DCHECK_EQ(0, rv);
130 }
131
Signal()132 void ConditionVariable::Signal() {
133 int rv = pthread_cond_signal(&condition_);
134 DCHECK_EQ(0, rv);
135 }
136
137 } // namespace base
138