1 // Copyright 2013 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_PLATFORM_CONDITION_VARIABLE_H_ 29 #define V8_PLATFORM_CONDITION_VARIABLE_H_ 30 31 #include "platform/mutex.h" 32 33 namespace v8 { 34 namespace internal { 35 36 // Forward declarations. 37 class ConditionVariableEvent; 38 class TimeDelta; 39 40 // ----------------------------------------------------------------------------- 41 // ConditionVariable 42 // 43 // This class is a synchronization primitive that can be used to block a thread, 44 // or multiple threads at the same time, until: 45 // - a notification is received from another thread, 46 // - a timeout expires, or 47 // - a spurious wakeup occurs 48 // Any thread that intends to wait on a ConditionVariable has to acquire a lock 49 // on a Mutex first. The |Wait()| and |WaitFor()| operations atomically release 50 // the mutex and suspend the execution of the calling thread. When the condition 51 // variable is notified, the thread is awakened, and the mutex is reacquired. 52 53 class ConditionVariable V8_FINAL { 54 public: 55 ConditionVariable(); 56 ~ConditionVariable(); 57 58 // If any threads are waiting on this condition variable, calling 59 // |NotifyOne()| unblocks one of the waiting threads. 60 void NotifyOne(); 61 62 // Unblocks all threads currently waiting for this condition variable. 63 void NotifyAll(); 64 65 // |Wait()| causes the calling thread to block until the condition variable is 66 // notified or a spurious wakeup occurs. Atomically releases the mutex, blocks 67 // the current executing thread, and adds it to the list of threads waiting on 68 // this condition variable. The thread will be unblocked when |NotifyAll()| or 69 // |NotifyOne()| is executed. It may also be unblocked spuriously. When 70 // unblocked, regardless of the reason, the lock on the mutex is reacquired 71 // and |Wait()| exits. 72 void Wait(Mutex* mutex); 73 74 // Atomically releases the mutex, blocks the current executing thread, and 75 // adds it to the list of threads waiting on this condition variable. The 76 // thread will be unblocked when |NotifyAll()| or |NotifyOne()| is executed, 77 // or when the relative timeout |rel_time| expires. It may also be unblocked 78 // spuriously. When unblocked, regardless of the reason, the lock on the mutex 79 // is reacquired and |WaitFor()| exits. Returns true if the condition variable 80 // was notified prior to the timeout. 81 bool WaitFor(Mutex* mutex, const TimeDelta& rel_time) V8_WARN_UNUSED_RESULT; 82 83 // The implementation-defined native handle type. 84 #if V8_OS_POSIX 85 typedef pthread_cond_t NativeHandle; 86 #elif V8_OS_WIN 87 struct Event; 88 class NativeHandle V8_FINAL { 89 public: NativeHandle()90 NativeHandle() : waitlist_(NULL), freelist_(NULL) {} 91 ~NativeHandle(); 92 93 Event* Pre() V8_WARN_UNUSED_RESULT; 94 void Post(Event* event, bool result); 95 mutex()96 Mutex* mutex() { return &mutex_; } waitlist()97 Event* waitlist() { return waitlist_; } 98 99 private: 100 Event* waitlist_; 101 Event* freelist_; 102 Mutex mutex_; 103 104 DISALLOW_COPY_AND_ASSIGN(NativeHandle); 105 }; 106 #endif 107 native_handle()108 NativeHandle& native_handle() { 109 return native_handle_; 110 } native_handle()111 const NativeHandle& native_handle() const { 112 return native_handle_; 113 } 114 115 private: 116 NativeHandle native_handle_; 117 118 DISALLOW_COPY_AND_ASSIGN(ConditionVariable); 119 }; 120 121 122 // POD ConditionVariable initialized lazily (i.e. the first time Pointer() is 123 // called). 124 // Usage: 125 // static LazyConditionVariable my_condvar = 126 // LAZY_CONDITION_VARIABLE_INITIALIZER; 127 // 128 // void my_function() { 129 // LockGuard<Mutex> lock_guard(&my_mutex); 130 // my_condvar.Pointer()->Wait(&my_mutex); 131 // } 132 typedef LazyStaticInstance<ConditionVariable, 133 DefaultConstructTrait<ConditionVariable>, 134 ThreadSafeInitOnceTrait>::type LazyConditionVariable; 135 136 #define LAZY_CONDITION_VARIABLE_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER 137 138 } } // namespace v8::internal 139 140 #endif // V8_PLATFORM_CONDITION_VARIABLE_H_ 141