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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()
     39     : main_(Thread::Current()),
     40       worker_(this),
     41       state_(kInit),
     42       refcount_(1) {
     43   main_->SignalQueueDestroyed.connect(this,
     44                                       &SignalThread::OnMainThreadDestroyed);
     45   worker_.SetName("SignalThread", this);
     46 }
     47 
     48 SignalThread::~SignalThread() {
     49   ASSERT(refcount_ == 0);
     50 }
     51 
     52 bool SignalThread::SetName(const std::string& name, const void* obj) {
     53   EnterExit ee(this);
     54   ASSERT(main_->IsCurrent());
     55   ASSERT(kInit == state_);
     56   return worker_.SetName(name, obj);
     57 }
     58 
     59 bool SignalThread::SetPriority(ThreadPriority priority) {
     60   EnterExit ee(this);
     61   ASSERT(main_->IsCurrent());
     62   ASSERT(kInit == state_);
     63   return worker_.SetPriority(priority);
     64 }
     65 
     66 void SignalThread::Start() {
     67   EnterExit ee(this);
     68   ASSERT(main_->IsCurrent());
     69   if (kInit == state_ || kComplete == state_) {
     70     state_ = kRunning;
     71     OnWorkStart();
     72     worker_.Start();
     73   } else {
     74     ASSERT(false);
     75   }
     76 }
     77 
     78 void SignalThread::Destroy(bool wait) {
     79   EnterExit ee(this);
     80   ASSERT(main_->IsCurrent());
     81   if ((kInit == state_) || (kComplete == state_)) {
     82     refcount_--;
     83   } else if (kRunning == state_ || kReleasing == state_) {
     84     state_ = kStopping;
     85     // OnWorkStop() must follow Quit(), so that when the thread wakes up due to
     86     // OWS(), ContinueWork() will return false.
     87     worker_.Quit();
     88     OnWorkStop();
     89     if (wait) {
     90       // Release the thread's lock so that it can return from ::Run.
     91       cs_.Leave();
     92       worker_.Stop();
     93       cs_.Enter();
     94       refcount_--;
     95     }
     96   } else {
     97     ASSERT(false);
     98   }
     99 }
    100 
    101 void SignalThread::Release() {
    102   EnterExit ee(this);
    103   ASSERT(main_->IsCurrent());
    104   if (kComplete == state_) {
    105     refcount_--;
    106   } else if (kRunning == state_) {
    107     state_ = kReleasing;
    108   } else {
    109     // if (kInit == state_) use Destroy()
    110     ASSERT(false);
    111   }
    112 }
    113 
    114 bool SignalThread::ContinueWork() {
    115   EnterExit ee(this);
    116   ASSERT(worker_.IsCurrent());
    117   return worker_.ProcessMessages(0);
    118 }
    119 
    120 void SignalThread::OnMessage(Message *msg) {
    121   EnterExit ee(this);
    122   if (ST_MSG_WORKER_DONE == msg->message_id) {
    123     ASSERT(main_->IsCurrent());
    124     OnWorkDone();
    125     bool do_delete = false;
    126     if (kRunning == state_) {
    127       state_ = kComplete;
    128     } else {
    129       do_delete = true;
    130     }
    131     if (kStopping != state_) {
    132       // Before signaling that the work is done, make sure that the worker
    133       // thread actually is done. We got here because DoWork() finished and
    134       // Run() posted the ST_MSG_WORKER_DONE message. This means the worker
    135       // thread is about to go away anyway, but sometimes it doesn't actually
    136       // finish before SignalWorkDone is processed, and for a reusable
    137       // SignalThread this makes an assert in thread.cc fire.
    138       //
    139       // Calling Stop() on the worker ensures that the OS thread that underlies
    140       // the worker will finish, and will be set to NULL, enabling us to call
    141       // Start() again.
    142       worker_.Stop();
    143       SignalWorkDone(this);
    144     }
    145     if (do_delete) {
    146       refcount_--;
    147     }
    148   }
    149 }
    150 
    151 void SignalThread::Run() {
    152   DoWork();
    153   {
    154     EnterExit ee(this);
    155     if (main_) {
    156       main_->Post(this, ST_MSG_WORKER_DONE);
    157     }
    158   }
    159 }
    160 
    161 void SignalThread::OnMainThreadDestroyed() {
    162   EnterExit ee(this);
    163   main_ = NULL;
    164 }
    165 
    166 }  // namespace talk_base
    167