1 /* 2 * libjingle 3 * Copyright 2014 Google Inc. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright notice, 9 * this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO 19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #ifndef TALK_BASE_ASYNCINVOKER_H_ 29 #define TALK_BASE_ASYNCINVOKER_H_ 30 31 #include "talk/base/asyncinvoker-inl.h" 32 #include "talk/base/bind.h" 33 #include "talk/base/sigslot.h" 34 #include "talk/base/scopedptrcollection.h" 35 #include "talk/base/thread.h" 36 37 namespace talk_base { 38 39 // Invokes function objects (aka functors) asynchronously on a Thread, and 40 // owns the lifetime of calls (ie, when this object is destroyed, calls in 41 // flight are cancelled). AsyncInvoker can optionally execute a user-specified 42 // function when the asynchronous call is complete, or operates in 43 // fire-and-forget mode otherwise. 44 // 45 // AsyncInvoker does not own the thread it calls functors on. 46 // 47 // A note about async calls and object lifetimes: users should 48 // be mindful of object lifetimes when calling functions asynchronously and 49 // ensure objects used by the function _cannot_ be deleted between the 50 // invocation and execution of the functor. AsyncInvoker is designed to 51 // help: any calls in flight will be cancelled when the AsyncInvoker used to 52 // make the call is destructed, and any calls executing will be allowed to 53 // complete before AsyncInvoker destructs. 54 // 55 // The easiest way to ensure lifetimes are handled correctly is to create a 56 // class that owns the Thread and AsyncInvoker objects, and then call its 57 // methods asynchronously as needed. 58 // 59 // Example: 60 // class MyClass { 61 // public: 62 // void FireAsyncTaskWithResult(Thread* thread, int x) { 63 // // Specify a callback to get the result upon completion. 64 // invoker_.AsyncInvoke<int>( 65 // thread, Bind(&MyClass::AsyncTaskWithResult, this, x), 66 // &MyClass::OnTaskComplete, this); 67 // } 68 // void FireAnotherAsyncTask(Thread* thread) { 69 // // No callback specified means fire-and-forget. 70 // invoker_.AsyncInvoke<void>( 71 // thread, Bind(&MyClass::AnotherAsyncTask, this)); 72 // 73 // private: 74 // int AsyncTaskWithResult(int x) { 75 // // Some long running process... 76 // return x * x; 77 // } 78 // void AnotherAsyncTask() { 79 // // Some other long running process... 80 // } 81 // void OnTaskComplete(int result) { result_ = result; } 82 // 83 // AsyncInvoker invoker_; 84 // int result_; 85 // }; 86 class AsyncInvoker : public MessageHandler { 87 public: 88 AsyncInvoker(); 89 virtual ~AsyncInvoker(); 90 91 // Call |functor| asynchronously on |thread|, with no callback upon 92 // completion. Returns immediately. 93 template <class ReturnT, class FunctorT> 94 void AsyncInvoke(Thread* thread, 95 const FunctorT& functor, 96 uint32 id = 0) { 97 AsyncClosure* closure = 98 new RefCountedObject<FireAndForgetAsyncClosure<FunctorT> >(functor); 99 DoInvoke(thread, closure, id); 100 } 101 102 // Call |functor| asynchronously on |thread|, calling |callback| when done. 103 template <class ReturnT, class FunctorT, class HostT> 104 void AsyncInvoke(Thread* thread, 105 const FunctorT& functor, 106 void (HostT::*callback)(ReturnT), 107 HostT* callback_host, 108 uint32 id = 0) { 109 AsyncClosure* closure = 110 new RefCountedObject<NotifyingAsyncClosure<ReturnT, FunctorT, HostT> >( 111 this, Thread::Current(), functor, callback, callback_host); 112 DoInvoke(thread, closure, id); 113 } 114 115 // Call |functor| asynchronously on |thread|, calling |callback| when done. 116 // Overloaded for void return. 117 template <class ReturnT, class FunctorT, class HostT> 118 void AsyncInvoke(Thread* thread, 119 const FunctorT& functor, 120 void (HostT::*callback)(), 121 HostT* callback_host, 122 uint32 id = 0) { 123 AsyncClosure* closure = 124 new RefCountedObject<NotifyingAsyncClosure<void, FunctorT, HostT> >( 125 this, Thread::Current(), functor, callback, callback_host); 126 DoInvoke(thread, closure, id); 127 } 128 129 // Synchronously execute on |thread| all outstanding calls we own 130 // that are pending on |thread|, and wait for calls to complete 131 // before returning. Optionally filter by message id. 132 // The destructor will not wait for outstanding calls, so if that 133 // behavior is desired, call Flush() before destroying this object. 134 void Flush(Thread* thread, uint32 id = MQID_ANY); 135 136 // Signaled when this object is destructed. 137 sigslot::signal0<> SignalInvokerDestroyed; 138 139 private: 140 virtual void OnMessage(Message* msg); 141 void DoInvoke(Thread* thread, AsyncClosure* closure, uint32 id); 142 143 bool destroying_; 144 145 DISALLOW_COPY_AND_ASSIGN(AsyncInvoker); 146 }; 147 148 } // namespace talk_base 149 150 151 #endif // TALK_BASE_ASYNCINVOKER_H_ 152
