src/content/browser/gamepad/gamepad_provider.cc

   1 // Copyright (c) 2012 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 <cmath>
   6 #include <set>
   7 #include <vector>
   8
   9 #include "base/bind.h"
  10 #include "base/logging.h"
  11 #include "base/message_loop/message_loop.h"
  12 #include "base/message_loop/message_loop_proxy.h"
  13 #include "base/threading/thread.h"
  14 #include "base/threading/thread_restrictions.h"
  15 #include "content/browser/gamepad/gamepad_data_fetcher.h"
  16 #include "content/browser/gamepad/gamepad_platform_data_fetcher.h"
  17 #include "content/browser/gamepad/gamepad_provider.h"
  18 #include "content/common/gamepad_hardware_buffer.h"
  19 #include "content/common/gamepad_messages.h"
  20 #include "content/common/gamepad_user_gesture.h"
  21
  22 namespace content {
  23
  24 GamepadProvider::ClosureAndThread::ClosureAndThread(
  25     const base::Closure& c,
  26     const scoped_refptr<base::MessageLoopProxy>& m)
  27     : closure(c),
  28       message_loop(m) {
  29 }
  30
  31 GamepadProvider::ClosureAndThread::~ClosureAndThread() {
  32 }
  33
  34 GamepadProvider::GamepadProvider()
  35     : is_paused_(true),
  36       have_scheduled_do_poll_(false),
  37       devices_changed_(true) {
  38   Initialize(scoped_ptr<GamepadDataFetcher>());
  39 }
  40
  41 GamepadProvider::GamepadProvider(scoped_ptr<GamepadDataFetcher> fetcher)
  42     : is_paused_(true),
  43       have_scheduled_do_poll_(false),
  44       devices_changed_(true) {
  45   Initialize(fetcher.Pass());
  46 }
  47
  48 GamepadProvider::~GamepadProvider() {
  49   base::SystemMonitor* monitor = base::SystemMonitor::Get();
  50   if (monitor)
  51     monitor->RemoveDevicesChangedObserver(this);
  52
  53   // Use Stop() to join the polling thread, as there may be pending callbacks
  54   // which dereference |polling_thread_|.
  55   polling_thread_->Stop();
  56   data_fetcher_.reset();
  57 }
  58
  59 base::SharedMemoryHandle GamepadProvider::GetSharedMemoryHandleForProcess(
  60     base::ProcessHandle process) {
  61   base::SharedMemoryHandle renderer_handle;
  62   gamepad_shared_memory_.ShareToProcess(process, &renderer_handle);
  63   return renderer_handle;
  64 }
  65
  66 void GamepadProvider::Pause() {
  67   {
  68     base::AutoLock lock(is_paused_lock_);
  69     is_paused_ = true;
  70   }
  71   base::MessageLoop* polling_loop = polling_thread_->message_loop();
  72   polling_loop->PostTask(
  73       FROM_HERE,
  74       base::Bind(&GamepadProvider::SendPauseHint, Unretained(this), true));
  75 }
  76
  77 void GamepadProvider::Resume() {
  78   {
  79     base::AutoLock lock(is_paused_lock_);
  80     if (!is_paused_)
  81         return;
  82     is_paused_ = false;
  83   }
  84
  85   base::MessageLoop* polling_loop = polling_thread_->message_loop();
  86   polling_loop->PostTask(
  87       FROM_HERE,
  88       base::Bind(&GamepadProvider::SendPauseHint, Unretained(this), false));
  89   polling_loop->PostTask(
  90       FROM_HERE,
  91       base::Bind(&GamepadProvider::ScheduleDoPoll, Unretained(this)));
  92 }
  93
  94 void GamepadProvider::RegisterForUserGesture(const base::Closure& closure) {
  95   base::AutoLock lock(user_gesture_lock_);
  96   user_gesture_observers_.push_back(ClosureAndThread(
  97       closure, base::MessageLoop::current()->message_loop_proxy()));
  98 }
  99
 100 void GamepadProvider::OnDevicesChanged(base::SystemMonitor::DeviceType type) {
 101   base::AutoLock lock(devices_changed_lock_);
 102   devices_changed_ = true;
 103 }
 104
 105 void GamepadProvider::Initialize(scoped_ptr<GamepadDataFetcher> fetcher) {
 106   size_t data_size = sizeof(GamepadHardwareBuffer);
 107   base::SystemMonitor* monitor = base::SystemMonitor::Get();
 108   if (monitor)
 109     monitor->AddDevicesChangedObserver(this);
 110   bool res = gamepad_shared_memory_.CreateAndMapAnonymous(data_size);
 111   CHECK(res);
 112   GamepadHardwareBuffer* hwbuf = SharedMemoryAsHardwareBuffer();
 113   memset(hwbuf, 0, sizeof(GamepadHardwareBuffer));
 114
 115   polling_thread_.reset(new base::Thread("Gamepad polling thread"));
 116 #if defined(OS_LINUX)
 117   // On Linux, the data fetcher needs to watch file descriptors, so the message
 118   // loop needs to be a libevent loop.
 119   const base::MessageLoop::Type kMessageLoopType = base::MessageLoop::TYPE_IO;
 120 #else
 121   // On Mac, the data fetcher uses IOKit which depends on CFRunLoop, so the
 122   // message loop needs to be a UI-type loop. On Windows it must be a UI loop
 123   // to properly pump the MessageWindow that captures device state.
 124   const base::MessageLoop::Type kMessageLoopType = base::MessageLoop::TYPE_UI;
 125 #endif
 126   polling_thread_->StartWithOptions(base::Thread::Options(kMessageLoopType, 0));
 127
 128   polling_thread_->message_loop()->PostTask(
 129       FROM_HERE,
 130       base::Bind(&GamepadProvider::DoInitializePollingThread,
 131                  base::Unretained(this),
 132                  base::Passed(&fetcher)));
 133 }
 134
 135 void GamepadProvider::DoInitializePollingThread(
 136     scoped_ptr<GamepadDataFetcher> fetcher) {
 137   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
 138   DCHECK(!data_fetcher_.get());  // Should only initialize once.
 139
 140   if (!fetcher)
 141     fetcher.reset(new GamepadPlatformDataFetcher);
 142   data_fetcher_ = fetcher.Pass();
 143 }
 144
 145 void GamepadProvider::SendPauseHint(bool paused) {
 146   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
 147   if (data_fetcher_)
 148     data_fetcher_->PauseHint(paused);
 149 }
 150
 151 void GamepadProvider::DoPoll() {
 152   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
 153   DCHECK(have_scheduled_do_poll_);
 154   have_scheduled_do_poll_ = false;
 155
 156   bool changed;
 157   GamepadHardwareBuffer* hwbuf = SharedMemoryAsHardwareBuffer();
 158
 159   ANNOTATE_BENIGN_RACE_SIZED(
 160       &hwbuf->buffer,
 161       sizeof(blink::WebGamepads),
 162       "Racey reads are discarded");
 163
 164   {
 165     base::AutoLock lock(devices_changed_lock_);
 166     changed = devices_changed_;
 167     devices_changed_ = false;
 168   }
 169
 170   // Acquire the SeqLock. There is only ever one writer to this data.
 171   // See gamepad_hardware_buffer.h.
 172   hwbuf->sequence.WriteBegin();
 173   data_fetcher_->GetGamepadData(&hwbuf->buffer, changed);
 174   hwbuf->sequence.WriteEnd();
 175
 176   CheckForUserGesture();
 177
 178   // Schedule our next interval of polling.
 179   ScheduleDoPoll();
 180 }
 181
 182 void GamepadProvider::ScheduleDoPoll() {
 183   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
 184   if (have_scheduled_do_poll_)
 185     return;
 186
 187   {
 188     base::AutoLock lock(is_paused_lock_);
 189     if (is_paused_)
 190       return;
 191   }
 192
 193   base::MessageLoop::current()->PostDelayedTask(
 194       FROM_HERE,
 195       base::Bind(&GamepadProvider::DoPoll, Unretained(this)),
 196       base::TimeDelta::FromMilliseconds(kDesiredSamplingIntervalMs));
 197   have_scheduled_do_poll_ = true;
 198 }
 199
 200 GamepadHardwareBuffer* GamepadProvider::SharedMemoryAsHardwareBuffer() {
 201   void* mem = gamepad_shared_memory_.memory();
 202   CHECK(mem);
 203   return static_cast<GamepadHardwareBuffer*>(mem);
 204 }
 205
 206 void GamepadProvider::CheckForUserGesture() {
 207   base::AutoLock lock(user_gesture_lock_);
 208   if (user_gesture_observers_.empty())
 209     return;  // Don't need to check if nobody is listening.
 210
 211   if (GamepadsHaveUserGesture(SharedMemoryAsHardwareBuffer()->buffer)) {
 212     for (size_t i = 0; i < user_gesture_observers_.size(); i++) {
 213       user_gesture_observers_[i].message_loop->PostTask(FROM_HERE,
 214           user_gesture_observers_[i].closure);
 215     }
 216     user_gesture_observers_.clear();
 217   }
 218 }
 219
 220 }  // namespace content