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      1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/threading/simple_thread.h"
      6 
      7 #include "base/logging.h"
      8 #include "base/strings/string_number_conversions.h"
      9 #include "base/threading/platform_thread.h"
     10 #include "base/threading/thread_restrictions.h"
     11 
     12 namespace base {
     13 
     14 SimpleThread::SimpleThread(const std::string& name_prefix)
     15     : name_prefix_(name_prefix), name_(name_prefix),
     16       thread_(), event_(true, false), tid_(0), joined_(false) {
     17 }
     18 
     19 SimpleThread::SimpleThread(const std::string& name_prefix,
     20                            const Options& options)
     21     : name_prefix_(name_prefix), name_(name_prefix), options_(options),
     22       thread_(), event_(true, false), tid_(0), joined_(false) {
     23 }
     24 
     25 SimpleThread::~SimpleThread() {
     26   DCHECK(HasBeenStarted()) << "SimpleThread was never started.";
     27   DCHECK(HasBeenJoined()) << "SimpleThread destroyed without being Join()ed.";
     28 }
     29 
     30 void SimpleThread::Start() {
     31   DCHECK(!HasBeenStarted()) << "Tried to Start a thread multiple times.";
     32   bool success = PlatformThread::Create(options_.stack_size(), this, &thread_);
     33   DCHECK(success);
     34   base::ThreadRestrictions::ScopedAllowWait allow_wait;
     35   event_.Wait();  // Wait for the thread to complete initialization.
     36 }
     37 
     38 void SimpleThread::Join() {
     39   DCHECK(HasBeenStarted()) << "Tried to Join a never-started thread.";
     40   DCHECK(!HasBeenJoined()) << "Tried to Join a thread multiple times.";
     41   PlatformThread::Join(thread_);
     42   joined_ = true;
     43 }
     44 
     45 bool SimpleThread::HasBeenStarted() {
     46   base::ThreadRestrictions::ScopedAllowWait allow_wait;
     47   return event_.IsSignaled();
     48 }
     49 
     50 void SimpleThread::ThreadMain() {
     51   tid_ = PlatformThread::CurrentId();
     52   // Construct our full name of the form "name_prefix_/TID".
     53   name_.push_back('/');
     54   name_.append(IntToString(tid_));
     55   PlatformThread::SetName(name_.c_str());
     56 
     57   // We've initialized our new thread, signal that we're done to Start().
     58   event_.Signal();
     59 
     60   Run();
     61 }
     62 
     63 DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
     64                                            const std::string& name_prefix)
     65     : SimpleThread(name_prefix),
     66       delegate_(delegate) {
     67 }
     68 
     69 DelegateSimpleThread::DelegateSimpleThread(Delegate* delegate,
     70                                            const std::string& name_prefix,
     71                                            const Options& options)
     72     : SimpleThread(name_prefix, options),
     73       delegate_(delegate) {
     74 }
     75 
     76 DelegateSimpleThread::~DelegateSimpleThread() {
     77 }
     78 
     79 void DelegateSimpleThread::Run() {
     80   DCHECK(delegate_) << "Tried to call Run without a delegate (called twice?)";
     81   delegate_->Run();
     82   delegate_ = NULL;
     83 }
     84 
     85 DelegateSimpleThreadPool::DelegateSimpleThreadPool(
     86     const std::string& name_prefix,
     87     int num_threads)
     88     : name_prefix_(name_prefix),
     89       num_threads_(num_threads),
     90       dry_(true, false) {
     91 }
     92 
     93 DelegateSimpleThreadPool::~DelegateSimpleThreadPool() {
     94   DCHECK(threads_.empty());
     95   DCHECK(delegates_.empty());
     96   DCHECK(!dry_.IsSignaled());
     97 }
     98 
     99 void DelegateSimpleThreadPool::Start() {
    100   DCHECK(threads_.empty()) << "Start() called with outstanding threads.";
    101   for (int i = 0; i < num_threads_; ++i) {
    102     DelegateSimpleThread* thread = new DelegateSimpleThread(this, name_prefix_);
    103     thread->Start();
    104     threads_.push_back(thread);
    105   }
    106 }
    107 
    108 void DelegateSimpleThreadPool::JoinAll() {
    109   DCHECK(!threads_.empty()) << "JoinAll() called with no outstanding threads.";
    110 
    111   // Tell all our threads to quit their worker loop.
    112   AddWork(NULL, num_threads_);
    113 
    114   // Join and destroy all the worker threads.
    115   for (int i = 0; i < num_threads_; ++i) {
    116     threads_[i]->Join();
    117     delete threads_[i];
    118   }
    119   threads_.clear();
    120   DCHECK(delegates_.empty());
    121 }
    122 
    123 void DelegateSimpleThreadPool::AddWork(Delegate* delegate, int repeat_count) {
    124   AutoLock locked(lock_);
    125   for (int i = 0; i < repeat_count; ++i)
    126     delegates_.push(delegate);
    127   // If we were empty, signal that we have work now.
    128   if (!dry_.IsSignaled())
    129     dry_.Signal();
    130 }
    131 
    132 void DelegateSimpleThreadPool::Run() {
    133   Delegate* work = NULL;
    134 
    135   while (true) {
    136     dry_.Wait();
    137     {
    138       AutoLock locked(lock_);
    139       if (!dry_.IsSignaled())
    140         continue;
    141 
    142       DCHECK(!delegates_.empty());
    143       work = delegates_.front();
    144       delegates_.pop();
    145 
    146       // Signal to any other threads that we're currently out of work.
    147       if (delegates_.empty())
    148         dry_.Reset();
    149     }
    150 
    151     // A NULL delegate pointer signals us to quit.
    152     if (!work)
    153       break;
    154 
    155     work->Run();
    156   }
    157 }
    158 
    159 }  // namespace base
    160