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| 1 // Copyright 2013 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 "mojo/shell/handle_watcher.h" | |
| 6 | |
| 7 #include <map> | |
| 8 #include <set> | |
| 9 #include <vector> | |
| 10 | |
| 11 #include "base/bind.h" | |
| 12 #include "base/lazy_instance.h" | |
| 13 #include "base/memory/weak_ptr.h" | |
| 14 #include "base/message_loop/message_loop.h" | |
| 15 #include "base/message_loop/message_loop_proxy.h" | |
| 16 #include "base/synchronization/lock.h" | |
| 17 #include "base/threading/thread.h" | |
| 18 #include "base/time/tick_clock.h" | |
| 19 #include "base/time/time.h" | |
| 20 #include "mojo/shell/scoped_message_pipe.h" | |
| 21 | |
| 22 namespace mojo { | |
| 23 namespace shell { | |
| 24 | |
| 25 typedef int WatcherID; | |
| 26 | |
| 27 namespace { | |
| 28 | |
| 29 const char kWatcherThreadName[] = "handle-watcher-thread"; | |
| 30 | |
| 31 // WatcherThreadManager -------------------------------------------------------- | |
| 32 | |
| 33 // WatcherThreadManager manages listening for the handles. It is a singleton. It | |
| 34 // spawns a thread that waits for any handle passed to StartWatching() to be | |
| 35 // ready. Additionally it creates a message pipe for communication between the | |
| 36 // two threads. The message pipe is used solely to wake up the background | |
| 37 // thread. This happens when the set of handles changes, or during shutdown. | |
| 38 class WatcherThreadManager { | |
| 39 public: | |
| 40 // Returns the shared instance. | |
| 41 static WatcherThreadManager* GetInstance(); | |
| 42 | |
| 43 // Starts watching the requested handle. Returns a unique ID that is used to | |
| 44 // stop watching the handle. When the handle is ready |callback| is notified | |
| 45 // on the thread StartWatching() was invoked on. | |
| 46 // This may be invoked on any thread. | |
| 47 WatcherID StartWatching(MojoHandle handle, | |
| 48 MojoWaitFlags wait_flags, | |
| 49 base::TimeTicks deadline, | |
| 50 const base::Closure& callback); | |
| 51 | |
| 52 // Stops watching a handle. | |
| 53 void StopWatching(WatcherID watcher_id); | |
| 54 | |
| 55 private: | |
| 56 friend struct base::DefaultLazyInstanceTraits<WatcherThreadManager>; | |
| 57 | |
| 58 // Tracks a single request. | |
| 59 struct HandleAndCallback { | |
| 60 HandleAndCallback() | |
| 61 : handle(MOJO_HANDLE_INVALID), | |
| 62 wait_flags(MOJO_WAIT_FLAG_NONE), | |
| 63 message_loop(NULL) {} | |
| 64 | |
| 65 MojoHandle handle; | |
| 66 MojoWaitFlags wait_flags; | |
| 67 base::TimeTicks deadline; | |
| 68 base::Closure callback; | |
| 69 scoped_refptr<base::MessageLoopProxy> message_loop; | |
| 70 }; | |
| 71 | |
| 72 // Contains the state needed for MojoWaitMany. | |
| 73 // NOTE: |handles| and |wait_flags| are separate vectors to make it easy to | |
| 74 // pass to MojoWaitMany. | |
| 75 struct WaitState { | |
| 76 // List of ids. | |
| 77 std::vector<WatcherID> ids; | |
| 78 | |
| 79 // List of handles. | |
| 80 std::vector<MojoHandle> handles; | |
| 81 | |
| 82 // List of flags each handle is waiting on. | |
| 83 std::vector<MojoWaitFlags> wait_flags; | |
| 84 | |
| 85 // First deadline. | |
| 86 MojoDeadline deadline; | |
| 87 | |
| 88 // Set of ids whose deadline has been reached. | |
| 89 std::set<WatcherID> deadline_exceeded; | |
| 90 }; | |
| 91 | |
| 92 typedef std::map<WatcherID, HandleAndCallback> IDToCallbackMap; | |
| 93 | |
| 94 WatcherThreadManager(); | |
| 95 ~WatcherThreadManager(); | |
| 96 | |
| 97 // Invoked on the background thread. Runs a loop waiting on current set of | |
| 98 // handles. | |
| 99 void RunOnBackgroundThread(); | |
| 100 | |
| 101 // Writes to the communication pipe to wake up the background thread. | |
| 102 void SignalBackgroundThread(); | |
| 103 | |
| 104 // Invoked when a handle associated with |id| should be removed and notified. | |
| 105 // |result| gives the reason for removing. | |
| 106 void RemoveAndNotify(WatcherID id, MojoResult result); | |
| 107 | |
| 108 // Removes all callbacks schedule for |handle|. This is used when a handle | |
| 109 // is identified as invalid. | |
| 110 void RemoveHandle(MojoHandle handle); | |
| 111 | |
| 112 MojoHandle read_handle() const { return control_pipe_.handle_0(); } | |
| 113 MojoHandle write_handle() const { return control_pipe_.handle_1(); } | |
| 114 | |
| 115 // Returns state needed for MojoWaitMany. | |
| 116 WaitState GetWaitState(); | |
| 117 | |
| 118 // Guards members accessed on both threads. | |
| 119 base::Lock lock_; | |
| 120 | |
| 121 // Used for communicating with the background thread. | |
| 122 ScopedMessagePipe control_pipe_; | |
| 123 | |
| 124 base::Thread thread_; | |
| 125 | |
| 126 // Maps from assigned id to the callback. | |
| 127 IDToCallbackMap id_to_callback_; | |
| 128 | |
| 129 // If true the background loop should exit. | |
| 130 bool quit_; | |
| 131 | |
| 132 DISALLOW_COPY_AND_ASSIGN(WatcherThreadManager); | |
| 133 }; | |
| 134 | |
| 135 WatcherThreadManager* WatcherThreadManager::GetInstance() { | |
| 136 static base::LazyInstance<WatcherThreadManager> instance = | |
| 137 LAZY_INSTANCE_INITIALIZER; | |
| 138 return &instance.Get(); | |
| 139 } | |
| 140 | |
| 141 WatcherID WatcherThreadManager::StartWatching(MojoHandle handle, | |
| 142 MojoWaitFlags wait_flags, | |
| 143 base::TimeTicks deadline, | |
| 144 const base::Closure& callback) { | |
| 145 WatcherID id = 0; | |
| 146 { | |
| 147 static int next_id = 0; | |
| 148 base::AutoLock lock(lock_); | |
| 149 // TODO(sky): worry about overflow? | |
| 150 id = ++next_id; | |
| 151 id_to_callback_[id].handle = handle; | |
| 152 id_to_callback_[id].callback = callback; | |
| 153 id_to_callback_[id].wait_flags = wait_flags; | |
| 154 id_to_callback_[id].deadline = deadline; | |
| 155 id_to_callback_[id].message_loop = base::MessageLoopProxy::current(); | |
| 156 } | |
| 157 SignalBackgroundThread(); | |
| 158 return id; | |
| 159 } | |
| 160 | |
| 161 | |
| 162 void WatcherThreadManager::StopWatching(WatcherID watcher_id) { | |
| 163 { | |
| 164 base::AutoLock lock(lock_); | |
| 165 // It's possible we've already serviced the handle but HandleWatcher hasn't | |
| 166 // processed it yet. | |
| 167 IDToCallbackMap::iterator i = id_to_callback_.find(watcher_id); | |
| 168 if (i == id_to_callback_.end()) | |
| 169 return; | |
| 170 id_to_callback_.erase(i); | |
| 171 } | |
| 172 SignalBackgroundThread(); | |
| 173 } | |
| 174 | |
| 175 WatcherThreadManager::WatcherThreadManager() | |
| 176 : thread_(kWatcherThreadName), | |
| 177 quit_(false) { | |
| 178 // TODO(sky): deal with error condition? | |
| 179 CHECK_NE(MOJO_HANDLE_INVALID, read_handle()); | |
| 180 thread_.Start(); | |
| 181 thread_.message_loop()->PostTask( | |
| 182 FROM_HERE, | |
| 183 base::Bind(&WatcherThreadManager::RunOnBackgroundThread, | |
| 184 base::Unretained(this))); | |
| 185 } | |
| 186 | |
| 187 WatcherThreadManager::~WatcherThreadManager() { | |
| 188 { | |
| 189 base::AutoLock lock(lock_); | |
| 190 quit_ = true; | |
| 191 } | |
| 192 SignalBackgroundThread(); | |
| 193 | |
| 194 thread_.Stop(); | |
| 195 } | |
| 196 | |
| 197 void WatcherThreadManager::RunOnBackgroundThread() { | |
| 198 while (true) { | |
| 199 const WaitState state = GetWaitState(); | |
| 200 for (std::set<WatcherID>::const_iterator i = | |
| 201 state.deadline_exceeded.begin(); | |
| 202 i != state.deadline_exceeded.end(); ++i) { | |
| 203 RemoveAndNotify(*i, MOJO_RESULT_DEADLINE_EXCEEDED); | |
| 204 } | |
| 205 const MojoResult result = MojoWaitMany(&state.handles.front(), | |
| 206 &state.wait_flags.front(), | |
| 207 state.handles.size(), | |
| 208 state.deadline); | |
| 209 | |
| 210 if (result >= 0) { | |
| 211 DCHECK_LT(result, static_cast<int>(state.handles.size())); | |
| 212 // Last handle is used to wake us up. | |
| 213 if (result == static_cast<int>(state.handles.size()) - 1) { | |
| 214 uint32_t num_bytes = 0; | |
| 215 MojoReadMessage(read_handle(), NULL, &num_bytes, NULL, 0, | |
| 216 MOJO_READ_MESSAGE_FLAG_MAY_DISCARD); | |
| 217 { | |
| 218 base::AutoLock lock(lock_); | |
| 219 if (quit_) | |
| 220 return; | |
| 221 } | |
| 222 } else { | |
| 223 RemoveAndNotify(state.ids[result], MOJO_RESULT_OK); | |
| 224 } | |
| 225 } else if (result == MOJO_RESULT_INVALID_ARGUMENT || | |
| 226 result == MOJO_RESULT_FAILED_PRECONDITION) { | |
| 227 // One of the handles is invalid or the flags supplied is invalid, remove | |
| 228 // it. | |
| 229 // Use -1 as last handle is used for communication and should never be | |
| 230 // invalid. | |
| 231 for (size_t i = 0; i < state.handles.size() - 1; ++i) { | |
| 232 const MojoResult result = | |
| 233 MojoWait(state.handles[i], state.wait_flags[i], 0); | |
| 234 switch (result) { | |
| 235 // TODO: do we really want to notify for all these conditions? | |
| 236 case MOJO_RESULT_OK: | |
| 237 case MOJO_RESULT_FAILED_PRECONDITION: | |
| 238 case MOJO_RESULT_INVALID_ARGUMENT: | |
| 239 RemoveAndNotify(state.ids[i], result); | |
| 240 break; | |
| 241 case MOJO_RESULT_DEADLINE_EXCEEDED: | |
| 242 break; | |
| 243 default: | |
| 244 NOTREACHED(); | |
| 245 } | |
| 246 } | |
| 247 } | |
| 248 } | |
| 249 } | |
| 250 | |
| 251 void WatcherThreadManager::SignalBackgroundThread() { | |
| 252 // TODO(sky): deal with error? | |
| 253 MojoWriteMessage(write_handle(), NULL, 0, NULL, 0, | |
| 254 MOJO_WRITE_MESSAGE_FLAG_NONE); | |
| 255 } | |
| 256 | |
| 257 void WatcherThreadManager::RemoveAndNotify(WatcherID id, MojoResult result) { | |
| 258 HandleAndCallback to_notify; | |
| 259 { | |
| 260 base::AutoLock lock(lock_); | |
| 261 IDToCallbackMap::iterator i = id_to_callback_.find(id); | |
| 262 if (i == id_to_callback_.end()) | |
| 263 return; | |
| 264 to_notify = i->second; | |
| 265 id_to_callback_.erase(i); | |
| 266 } | |
| 267 to_notify.message_loop->PostTask(FROM_HERE, to_notify.callback); | |
| 268 } | |
| 269 | |
| 270 void WatcherThreadManager::RemoveHandle(MojoHandle handle) { | |
| 271 { | |
| 272 base::AutoLock lock(lock_); | |
| 273 for (IDToCallbackMap::iterator i = id_to_callback_.begin(); | |
| 274 i != id_to_callback_.end(); ) { | |
| 275 if (i->second.handle == handle) { | |
| 276 id_to_callback_.erase(i++); | |
| 277 } else { | |
| 278 ++i; | |
| 279 } | |
| 280 } | |
| 281 } | |
| 282 } | |
| 283 | |
| 284 WatcherThreadManager::WaitState WatcherThreadManager::GetWaitState() { | |
| 285 WaitState state; | |
| 286 const base::TimeTicks now(HandleWatcher::NowTicks()); | |
| 287 base::TimeDelta deadline; | |
| 288 { | |
| 289 base::AutoLock lock(lock_); | |
| 290 for (IDToCallbackMap::const_iterator i = id_to_callback_.begin(); | |
| 291 i != id_to_callback_.end(); ++i) { | |
| 292 if (!i->second.deadline.is_null()) { | |
| 293 if (i->second.deadline <= now) { | |
| 294 state.deadline_exceeded.insert(i->first); | |
| 295 continue; | |
| 296 } else { | |
| 297 const base::TimeDelta delta = i->second.deadline - now; | |
| 298 if (deadline == base::TimeDelta() || delta < deadline) | |
| 299 deadline = delta; | |
| 300 } | |
| 301 } | |
| 302 state.ids.push_back(i->first); | |
| 303 state.handles.push_back(i->second.handle); | |
| 304 state.wait_flags.push_back(i->second.wait_flags); | |
| 305 } | |
| 306 } | |
| 307 state.ids.push_back(0); | |
| 308 state.handles.push_back(read_handle()); | |
| 309 state.wait_flags.push_back(MOJO_WAIT_FLAG_READABLE); | |
| 310 state.deadline = (deadline == base::TimeDelta()) ? | |
| 311 MOJO_DEADLINE_INDEFINITE : deadline.InMicroseconds(); | |
| 312 return state; | |
| 313 } | |
| 314 | |
| 315 } // namespace | |
| 316 | |
| 317 // HandleWatcher::StartState --------------------------------------------------- | |
| 318 | |
| 319 // Contains the information passed to Start(). | |
| 320 struct HandleWatcher::StartState { | |
| 321 explicit StartState(HandleWatcher* watcher) : weak_factory(watcher) { | |
| 322 } | |
| 323 | |
| 324 ~StartState() { | |
| 325 } | |
| 326 | |
| 327 // ID assigned by WatcherThreadManager. | |
| 328 WatcherID watcher_id; | |
| 329 | |
| 330 // Callback to notify when done. | |
| 331 base::Closure callback; | |
| 332 | |
| 333 // When Start() is invoked a callback is passed to WatcherThreadManager | |
| 334 // using a WeakRef from |weak_refactory_|. The callback invokes | |
| 335 // OnHandleReady() (on the thread Start() is invoked from) which in turn | |
| 336 // notifies |callback_|. Doing this allows us to reset state when the handle | |
| 337 // is ready, and then notify the callback. Doing this also means Stop() | |
| 338 // cancels any pending callbacks that may be inflight. | |
| 339 base::WeakPtrFactory<HandleWatcher> weak_factory; | |
| 340 }; | |
| 341 | |
| 342 // HandleWatcher --------------------------------------------------------------- | |
| 343 | |
| 344 // static | |
| 345 base::TickClock* HandleWatcher::tick_clock_ = NULL; | |
| 346 | |
| 347 HandleWatcher::HandleWatcher() { | |
| 348 } | |
| 349 | |
| 350 HandleWatcher::~HandleWatcher() { | |
| 351 Stop(); | |
| 352 } | |
| 353 | |
| 354 void HandleWatcher::Start(MojoHandle handle, | |
| 355 MojoWaitFlags wait_flags, | |
| 356 MojoDeadline deadline, | |
| 357 const base::Closure& callback) { | |
| 358 DCHECK_NE(MOJO_HANDLE_INVALID, handle); | |
| 359 DCHECK_NE(MOJO_WAIT_FLAG_NONE, wait_flags); | |
| 360 | |
| 361 Stop(); | |
| 362 | |
| 363 start_state_.reset(new StartState(this)); | |
| 364 start_state_->callback = callback; | |
| 365 start_state_->watcher_id = | |
| 366 WatcherThreadManager::GetInstance()->StartWatching( | |
| 367 handle, | |
| 368 wait_flags, | |
| 369 MojoDeadlineToTimeTicks(deadline), | |
| 370 base::Bind(&HandleWatcher::OnHandleReady, | |
| 371 start_state_->weak_factory.GetWeakPtr())); | |
| 372 } | |
| 373 | |
| 374 void HandleWatcher::Stop() { | |
| 375 if (!start_state_.get()) | |
| 376 return; | |
| 377 | |
| 378 scoped_ptr<StartState> old_state(start_state_.Pass()); | |
| 379 WatcherThreadManager::GetInstance()->StopWatching(old_state->watcher_id); | |
| 380 } | |
| 381 | |
| 382 void HandleWatcher::OnHandleReady() { | |
| 383 DCHECK(start_state_.get()); | |
| 384 scoped_ptr<StartState> old_state(start_state_.Pass()); | |
| 385 old_state->callback.Run(); | |
| 386 } | |
| 387 | |
| 388 // static | |
| 389 base::TimeTicks HandleWatcher::NowTicks() { | |
| 390 return tick_clock_ ? tick_clock_->NowTicks() : base::TimeTicks::Now(); | |
| 391 } | |
| 392 | |
| 393 // static | |
| 394 base::TimeTicks HandleWatcher::MojoDeadlineToTimeTicks(MojoDeadline deadline) { | |
| 395 return deadline == MOJO_DEADLINE_INDEFINITE ? base::TimeTicks() : | |
| 396 NowTicks() + base::TimeDelta::FromMicroseconds(deadline); | |
| 397 } | |
| 398 | |
| 399 } // namespace shell | |
| 400 } // namespace mojo | |
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Chromium Code Reviews
Issue 64973002:
Moves some files into mojo/common (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src