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      1 /*
      2  * libjingle
      3  * Copyright 2004--2010, 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/worker.h"
     29 
     30 #include "talk/base/common.h"
     31 #include "talk/base/logging.h"
     32 #include "talk/base/thread.h"
     33 
     34 namespace talk_base {
     35 
     36 enum {
     37   MSG_HAVEWORK = 0,
     38 };
     39 
     40 Worker::Worker() : worker_thread_(NULL) {}
     41 
     42 Worker::~Worker() {
     43   // We need to already be stopped before being destroyed. We cannot call
     44   // StopWork() from here because the subclass's data has already been
     45   // destructed, so OnStop() cannot be called.
     46   ASSERT(!worker_thread_);
     47 }
     48 
     49 bool Worker::StartWork() {
     50   talk_base::Thread *me = talk_base::Thread::Current();
     51   if (worker_thread_) {
     52     if (worker_thread_ == me) {
     53       // Already working on this thread, so nothing to do.
     54       return true;
     55     } else {
     56       LOG(LS_ERROR) << "Automatically switching threads is not supported";
     57       ASSERT(false);
     58       return false;
     59     }
     60   }
     61   worker_thread_ = me;
     62   OnStart();
     63   return true;
     64 }
     65 
     66 bool Worker::StopWork() {
     67   if (!worker_thread_) {
     68     // Already not working, so nothing to do.
     69     return true;
     70   } else if (worker_thread_ != talk_base::Thread::Current()) {
     71     LOG(LS_ERROR) << "Stopping from a different thread is not supported";
     72     ASSERT(false);
     73     return false;
     74   }
     75   OnStop();
     76   worker_thread_->Clear(this, MSG_HAVEWORK);
     77   worker_thread_ = NULL;
     78   return true;
     79 }
     80 
     81 void Worker::HaveWork() {
     82   ASSERT(worker_thread_ != NULL);
     83   worker_thread_->Post(this, MSG_HAVEWORK);
     84 }
     85 
     86 void Worker::OnMessage(talk_base::Message *msg) {
     87   ASSERT(msg->message_id == MSG_HAVEWORK);
     88   ASSERT(worker_thread_ == talk_base::Thread::Current());
     89   OnHaveWork();
     90 }
     91 
     92 }  // namespace talk_base
     93