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| 1 // Copyright 2017 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/edk/system/watch.h" |
| 6 |
| 7 #include "mojo/edk/system/request_context.h" |
| 8 #include "mojo/edk/system/watcher_dispatcher.h" |
| 9 |
| 10 namespace mojo { |
| 11 namespace edk { |
| 12 |
| 13 Watch::Watch(const scoped_refptr<WatcherDispatcher>& watcher, |
| 14 const scoped_refptr<Dispatcher>& dispatcher, |
| 15 uintptr_t context, |
| 16 MojoHandleSignals signals) |
| 17 : watcher_(watcher), |
| 18 dispatcher_(dispatcher), |
| 19 context_(context), |
| 20 signals_(signals) {} |
| 21 |
| 22 MojoResult Watch::NotifyState(const HandleSignalsState& state, |
| 23 bool allowed_to_call_callback) { |
| 24 // NOTE: This method must NEVER call into |dispatcher_| directly, because it |
| 25 // may be called while |dispatcher_| holds a lock. |
| 26 |
| 27 RequestContext* const request_context = RequestContext::current(); |
| 28 if (state.satisfies(signals_)) { |
| 29 if (allowed_to_call_callback) { |
| 30 request_context->AddWatchNotifyFinalizer(this, MOJO_RESULT_OK, state); |
| 31 } |
| 32 return MOJO_RESULT_OK; |
| 33 } else if (!state.can_satisfy(signals_)) { |
| 34 if (allowed_to_call_callback) { |
| 35 request_context->AddWatchNotifyFinalizer( |
| 36 this, MOJO_RESULT_FAILED_PRECONDITION, state); |
| 37 } |
| 38 return MOJO_RESULT_FAILED_PRECONDITION; |
| 39 } |
| 40 |
| 41 return MOJO_RESULT_SHOULD_WAIT; |
| 42 } |
| 43 |
| 44 void Watch::Cancel() { |
| 45 RequestContext::current()->AddWatchCancelFinalizer(this); |
| 46 } |
| 47 |
| 48 void Watch::InvokeCallback(MojoResult result, |
| 49 const HandleSignalsState& state, |
| 50 MojoWatcherNotificationFlags flags) { |
| 51 // We hold the lock through invocation to ensure that only one notification |
| 52 // callback runs for this context at any given time. |
| 53 base::AutoLock lock(notification_lock_); |
| 54 if (result == MOJO_RESULT_CANCELLED) { |
| 55 // Make sure cancellation is the last notification we dispatch. |
| 56 DCHECK(!is_cancelled_); |
| 57 is_cancelled_ = true; |
| 58 } else if (is_cancelled_) { |
| 59 return; |
| 60 } |
| 61 |
| 62 // NOTE: This will acquire |watcher_|'s internal lock. It's safe because a |
| 63 // thread can only enter InvokeCallback() from within a RequestContext |
| 64 // destructor where no dispatcher locks are held. |
| 65 watcher_->InvokeWatchCallback(context_, result, state, flags); |
| 66 } |
| 67 |
| 68 Watch::~Watch() {} |
| 69 |
| 70 } // namespace edk |
| 71 } // namespace mojo |
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