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      1 /*
      2  * libjingle
      3  * Copyright 2004--2009, 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 #include "talk/base/signalthread.h"
     29 
     30 #include "talk/base/common.h"
     31 
     32 namespace talk_base {
     33 
     34 ///////////////////////////////////////////////////////////////////////////////
     35 // SignalThread
     36 ///////////////////////////////////////////////////////////////////////////////
     37 
     38 SignalThread::SignalThread() : main_(Thread::Current()), state_(kInit) {
     39   main_->SignalQueueDestroyed.connect(this,
     40                                       &SignalThread::OnMainThreadDestroyed);
     41   refcount_ = 1;
     42   worker_.parent_ = this;
     43   worker_.SetName("SignalThread", this);
     44 }
     45 
     46 SignalThread::~SignalThread() {
     47   ASSERT(refcount_ == 0);
     48 }
     49 
     50 bool SignalThread::SetName(const std::string& name, const void* obj) {
     51   EnterExit ee(this);
     52   ASSERT(main_->IsCurrent());
     53   ASSERT(kInit == state_);
     54   return worker_.SetName(name, obj);
     55 }
     56 
     57 bool SignalThread::SetPriority(ThreadPriority priority) {
     58   EnterExit ee(this);
     59   ASSERT(main_->IsCurrent());
     60   ASSERT(kInit == state_);
     61   return worker_.SetPriority(priority);
     62 }
     63 
     64 void SignalThread::Start() {
     65   EnterExit ee(this);
     66   ASSERT(main_->IsCurrent());
     67   if (kInit == state_ || kComplete == state_) {
     68     state_ = kRunning;
     69     OnWorkStart();
     70     worker_.Start();
     71   } else {
     72     ASSERT(false);
     73   }
     74 }
     75 
     76 void SignalThread::Destroy(bool wait) {
     77   EnterExit ee(this);
     78   ASSERT(main_->IsCurrent());
     79   if ((kInit == state_) || (kComplete == state_)) {
     80     refcount_--;
     81   } else if (kRunning == state_ || kReleasing == state_) {
     82     state_ = kStopping;
     83     // OnWorkStop() must follow Quit(), so that when the thread wakes up due to
     84     // OWS(), ContinueWork() will return false.
     85     worker_.Quit();
     86     OnWorkStop();
     87     if (wait) {
     88       // Release the thread's lock so that it can return from ::Run.
     89       cs_.Leave();
     90       worker_.Stop();
     91       cs_.Enter();
     92       refcount_--;
     93     }
     94   } else {
     95     ASSERT(false);
     96   }
     97 }
     98 
     99 void SignalThread::Release() {
    100   EnterExit ee(this);
    101   ASSERT(main_->IsCurrent());
    102   if (kComplete == state_) {
    103     refcount_--;
    104   } else if (kRunning == state_) {
    105     state_ = kReleasing;
    106   } else {
    107     // if (kInit == state_) use Destroy()
    108     ASSERT(false);
    109   }
    110 }
    111 
    112 bool SignalThread::ContinueWork() {
    113   EnterExit ee(this);
    114   ASSERT(worker_.IsCurrent());
    115   return worker_.ProcessMessages(0);
    116 }
    117 
    118 void SignalThread::OnMessage(Message *msg) {
    119   EnterExit ee(this);
    120   if (ST_MSG_WORKER_DONE == msg->message_id) {
    121     ASSERT(main_->IsCurrent());
    122     OnWorkDone();
    123     bool do_delete = false;
    124     if (kRunning == state_) {
    125       state_ = kComplete;
    126     } else {
    127       do_delete = true;
    128     }
    129     if (kStopping != state_) {
    130       // Before signaling that the work is done, make sure that the worker
    131       // thread actually is done. We got here because DoWork() finished and
    132       // Run() posted the ST_MSG_WORKER_DONE message. This means the worker
    133       // thread is about to go away anyway, but sometimes it doesn't actually
    134       // finish before SignalWorkDone is processed, and for a reusable
    135       // SignalThread this makes an assert in thread.cc fire.
    136       //
    137       // Calling Stop() on the worker ensures that the OS thread that underlies
    138       // the worker will finish, and will be set to NULL, enabling us to call
    139       // Start() again.
    140       worker_.Stop();
    141       SignalWorkDone(this);
    142     }
    143     if (do_delete) {
    144       refcount_--;
    145     }
    146   }
    147 }
    148 
    149 void SignalThread::Run() {
    150   DoWork();
    151   {
    152     EnterExit ee(this);
    153     if (main_) {
    154       main_->Post(this, ST_MSG_WORKER_DONE);
    155     }
    156   }
    157 }
    158 
    159 void SignalThread::OnMainThreadDestroyed() {
    160   EnterExit ee(this);
    161   main_ = NULL;
    162 }
    163 
    164 }  // namespace talk_base
    165