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_SEMAPHORE_H_ 29 #define V8_PLATFORM_SEMAPHORE_H_ 30 31 #include "../lazy-instance.h" 32 #if V8_OS_WIN 33 #include "../win32-headers.h" 34 #endif 35 36 #if V8_OS_MACOSX 37 #include <mach/semaphore.h> // NOLINT 38 #elif V8_OS_POSIX 39 #include <semaphore.h> // NOLINT 40 #endif 41 42 namespace v8 { 43 namespace internal { 44 45 // Forward declarations. 46 class TimeDelta; 47 48 // ---------------------------------------------------------------------------- 49 // Semaphore 50 // 51 // A semaphore object is a synchronization object that maintains a count. The 52 // count is decremented each time a thread completes a wait for the semaphore 53 // object and incremented each time a thread signals the semaphore. When the 54 // count reaches zero, threads waiting for the semaphore blocks until the 55 // count becomes non-zero. 56 57 class Semaphore V8_FINAL { 58 public: 59 explicit Semaphore(int count); 60 ~Semaphore(); 61 62 // Increments the semaphore counter. 63 void Signal(); 64 65 // Suspends the calling thread until the semaphore counter is non zero 66 // and then decrements the semaphore counter. 67 void Wait(); 68 69 // Suspends the calling thread until the counter is non zero or the timeout 70 // time has passed. If timeout happens the return value is false and the 71 // counter is unchanged. Otherwise the semaphore counter is decremented and 72 // true is returned. 73 bool WaitFor(const TimeDelta& rel_time) V8_WARN_UNUSED_RESULT; 74 75 #if V8_OS_MACOSX 76 typedef semaphore_t NativeHandle; 77 #elif V8_OS_POSIX 78 typedef sem_t NativeHandle; 79 #elif V8_OS_WIN 80 typedef HANDLE NativeHandle; 81 #endif 82 native_handle()83 NativeHandle& native_handle() { 84 return native_handle_; 85 } native_handle()86 const NativeHandle& native_handle() const { 87 return native_handle_; 88 } 89 90 private: 91 NativeHandle native_handle_; 92 93 DISALLOW_COPY_AND_ASSIGN(Semaphore); 94 }; 95 96 97 // POD Semaphore initialized lazily (i.e. the first time Pointer() is called). 98 // Usage: 99 // // The following semaphore starts at 0. 100 // static LazySemaphore<0>::type my_semaphore = LAZY_SEMAPHORE_INITIALIZER; 101 // 102 // void my_function() { 103 // // Do something with my_semaphore.Pointer(). 104 // } 105 // 106 107 template <int N> 108 struct CreateSemaphoreTrait { CreateCreateSemaphoreTrait109 static Semaphore* Create() { 110 return new Semaphore(N); 111 } 112 }; 113 114 template <int N> 115 struct LazySemaphore { 116 typedef typename LazyDynamicInstance< 117 Semaphore, 118 CreateSemaphoreTrait<N>, 119 ThreadSafeInitOnceTrait>::type type; 120 }; 121 122 #define LAZY_SEMAPHORE_INITIALIZER LAZY_DYNAMIC_INSTANCE_INITIALIZER 123 124 } } // namespace v8::internal 125 126 #endif // V8_PLATFORM_SEMAPHORE_H_ 127