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Side by Side Diff: third_party/WebKit/Source/core/mojo/MojoWatcher.cpp

Issue 2725133002: Mojo: Armed Watchers (Closed)
Patch Set: . Created 3 years, 9 months ago
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1 // Copyright 2017 The Chromium Authors. All rights reserved. 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 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "core/mojo/MojoWatcher.h" 5 #include "core/mojo/MojoWatcher.h"
6 6
7 #include "bindings/core/v8/MojoWatchCallback.h" 7 #include "bindings/core/v8/MojoWatchCallback.h"
8 #include "bindings/core/v8/ScriptState.h" 8 #include "bindings/core/v8/ScriptState.h"
9 #include "core/dom/ExecutionContext.h" 9 #include "core/dom/ExecutionContext.h"
10 #include "core/dom/TaskRunnerHelper.h" 10 #include "core/dom/TaskRunnerHelper.h"
11 #include "core/mojo/MojoHandleSignals.h" 11 #include "core/mojo/MojoHandleSignals.h"
12 #include "platform/CrossThreadFunctional.h" 12 #include "platform/CrossThreadFunctional.h"
13 #include "platform/WebTaskRunner.h" 13 #include "platform/WebTaskRunner.h"
14 14
15 namespace blink { 15 namespace blink {
16 16
17 static void runWatchCallback(MojoWatchCallback* callback, 17 static void runWatchCallback(MojoWatchCallback* callback,
18 ScriptWrappable* wrappable, 18 ScriptWrappable* wrappable,
19 MojoResult result) { 19 MojoResult result) {
20 callback->call(wrappable, result); 20 callback->call(wrappable, result);
21 } 21 }
22 22
23 // static
23 MojoWatcher* MojoWatcher::create(mojo::Handle handle, 24 MojoWatcher* MojoWatcher::create(mojo::Handle handle,
24 const MojoHandleSignals& signalsDict, 25 const MojoHandleSignals& signalsDict,
25 MojoWatchCallback* callback, 26 MojoWatchCallback* callback,
26 ExecutionContext* context) { 27 ExecutionContext* context) {
27 MojoWatcher* watcher = new MojoWatcher(context, callback); 28 MojoWatcher* watcher = new MojoWatcher(context, callback);
28 MojoResult result = watcher->watch(handle, signalsDict); 29 MojoResult result = watcher->watch(handle, signalsDict);
29 // TODO(alokp): Consider raising an exception. 30 // TODO(alokp): Consider raising an exception.
30 // Current clients expect to recieve the initial error returned by MojoWatch 31 // Current clients expect to recieve the initial error returned by MojoWatch
31 // via watch callback. 32 // via watch callback.
32 // 33 //
33 // Note that the usage of wrapPersistent is intentional so that the intial 34 // Note that the usage of wrapPersistent is intentional so that the intial
34 // error is guaranteed to be reported to the client in case where the given 35 // error is guaranteed to be reported to the client in case where the given
35 // handle is invalid and garbage collection happens before the callback 36 // handle is invalid and garbage collection happens before the callback
36 // is scheduled. 37 // is scheduled.
37 if (result != MOJO_RESULT_OK) { 38 if (result != MOJO_RESULT_OK) {
38 watcher->m_taskRunner->postTask( 39 watcher->m_taskRunner->postTask(
39 BLINK_FROM_HERE, WTF::bind(&runWatchCallback, wrapPersistent(callback), 40 BLINK_FROM_HERE, WTF::bind(&runWatchCallback, wrapPersistent(callback),
40 wrapPersistent(watcher), result)); 41 wrapPersistent(watcher), result));
41 } 42 }
42 return watcher; 43 return watcher;
43 } 44 }
44 45
45 MojoWatcher::MojoWatcher(ExecutionContext* context, MojoWatchCallback* callback)
46 : ContextLifecycleObserver(context),
47 m_taskRunner(TaskRunnerHelper::get(TaskType::UnspecedTimer, context)),
48 m_callback(this, callback) {}
49
50 MojoWatcher::~MojoWatcher() { 46 MojoWatcher::~MojoWatcher() {
51 DCHECK(!m_handle.is_valid()); 47 DCHECK(!m_handle.is_valid());
52 } 48 }
53 49
54 MojoResult MojoWatcher::watch(mojo::Handle handle, 50 MojoResult MojoWatcher::cancel() {
55 const MojoHandleSignals& signalsDict) { 51 if (!m_watcherHandle.is_valid())
56 ::MojoHandleSignals signals = MOJO_HANDLE_SIGNAL_NONE; 52 return MOJO_RESULT_INVALID_ARGUMENT;
57 if (signalsDict.readable())
58 signals |= MOJO_HANDLE_SIGNAL_READABLE;
59 if (signalsDict.writable())
60 signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
61 if (signalsDict.peerClosed())
62 signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
63 53
64 MojoResult result = 54 m_watcherHandle.reset();
65 MojoWatch(handle.value(), signals, &MojoWatcher::onHandleReady, 55 return MOJO_RESULT_OK;
66 reinterpret_cast<uintptr_t>(this));
67 if (result == MOJO_RESULT_OK) {
68 m_handle = handle;
69 }
70 return result;
71 }
72
73 MojoResult MojoWatcher::cancel() {
74 if (!m_handle.is_valid())
75 return MOJO_RESULT_OK;
76
77 MojoResult result =
78 MojoCancelWatch(m_handle.value(), reinterpret_cast<uintptr_t>(this));
79 m_handle = mojo::Handle();
80 return result;
81 } 56 }
82 57
83 DEFINE_TRACE(MojoWatcher) { 58 DEFINE_TRACE(MojoWatcher) {
84 visitor->trace(m_callback); 59 visitor->trace(m_callback);
85 ContextLifecycleObserver::trace(visitor); 60 ContextLifecycleObserver::trace(visitor);
86 } 61 }
87 62
88 DEFINE_TRACE_WRAPPERS(MojoWatcher) { 63 DEFINE_TRACE_WRAPPERS(MojoWatcher) {
89 visitor->traceWrappers(m_callback); 64 visitor->traceWrappers(m_callback);
90 } 65 }
91 66
92 bool MojoWatcher::hasPendingActivity() const { 67 bool MojoWatcher::hasPendingActivity() const {
93 return m_handle.is_valid(); 68 return m_handle.is_valid();
94 } 69 }
95 70
96 void MojoWatcher::contextDestroyed(ExecutionContext*) { 71 void MojoWatcher::contextDestroyed(ExecutionContext*) {
97 cancel(); 72 cancel();
98 } 73 }
99 74
75 MojoWatcher::MojoWatcher(ExecutionContext* context, MojoWatchCallback* callback)
76 : ContextLifecycleObserver(context),
77 m_taskRunner(TaskRunnerHelper::get(TaskType::UnspecedTimer, context)),
78 m_callback(this, callback) {}
79
80 MojoResult MojoWatcher::watch(mojo::Handle handle,
81 const MojoHandleSignals& signalsDict) {
82 ::MojoHandleSignals signals = MOJO_HANDLE_SIGNAL_NONE;
83 if (signalsDict.readable())
84 signals |= MOJO_HANDLE_SIGNAL_READABLE;
85 if (signalsDict.writable())
86 signals |= MOJO_HANDLE_SIGNAL_WRITABLE;
87 if (signalsDict.peerClosed())
88 signals |= MOJO_HANDLE_SIGNAL_PEER_CLOSED;
89
90 MojoResult result =
91 mojo::CreateWatcher(&MojoWatcher::onHandleReady, &m_watcherHandle);
92 DCHECK_EQ(MOJO_RESULT_OK, result);
93
94 result = MojoWatch(m_watcherHandle.get().value(), handle.value(), signals,
95 reinterpret_cast<uintptr_t>(this));
96 if (result != MOJO_RESULT_OK)
97 return result;
98
99 m_handle = handle;
100
101 MojoResult readyResult;
102 result = arm(&readyResult);
103 if (result == MOJO_RESULT_OK)
104 return result;
105
106 // We couldn't arm the watcher because the handle is already ready to
107 // trigger a success notification. Post a notification manually.
108 DCHECK_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
109 m_taskRunner->postTask(BLINK_FROM_HERE,
110 WTF::bind(&MojoWatcher::runReadyCallback,
111 wrapPersistent(this), readyResult));
112 return MOJO_RESULT_OK;
113 }
114
115 MojoResult MojoWatcher::arm(MojoResult* readyResult) {
116 // Nothing to do if the watcher is inactive.
117 if (!m_handle.is_valid())
118 return MOJO_RESULT_OK;
119
120 uint32_t numReadyContexts = 1;
121 uintptr_t readyContext;
122 MojoResult localReadyResult;
123 MojoHandleSignalsState readySignals;
124 MojoResult result =
125 MojoArmWatcher(m_watcherHandle.get().value(), &numReadyContexts,
126 &readyContext, &localReadyResult, &readySignals);
127 if (result == MOJO_RESULT_OK)
128 return MOJO_RESULT_OK;
129
130 DCHECK_EQ(MOJO_RESULT_FAILED_PRECONDITION, result);
131 DCHECK_EQ(1u, numReadyContexts);
132 DCHECK_EQ(reinterpret_cast<uintptr_t>(this), readyContext);
133 *readyResult = localReadyResult;
134 return result;
135 }
136
100 void MojoWatcher::onHandleReady(uintptr_t context, 137 void MojoWatcher::onHandleReady(uintptr_t context,
101 MojoResult result, 138 MojoResult result,
102 MojoHandleSignalsState, 139 MojoHandleSignalsState,
103 MojoWatchNotificationFlags) { 140 MojoWatcherNotificationFlags) {
104 // It is safe to assume the MojoWatcher still exists because this 141 // It is safe to assume the MojoWatcher still exists. It stays alive at least
105 // callback will never be run after MojoWatcher destructor, 142 // as long as |m_handle| is valid, and |m_handle| is only reset after we
106 // which cancels the watch. 143 // dispatch a |MOJO_RESULT_CANCELLED| notification. That is always the last
144 // notification received by this callback.
107 MojoWatcher* watcher = reinterpret_cast<MojoWatcher*>(context); 145 MojoWatcher* watcher = reinterpret_cast<MojoWatcher*>(context);
108 watcher->m_taskRunner->postTask( 146 watcher->m_taskRunner->postTask(
109 BLINK_FROM_HERE, 147 BLINK_FROM_HERE,
110 crossThreadBind(&MojoWatcher::runReadyCallback, 148 crossThreadBind(&MojoWatcher::runReadyCallback,
111 wrapCrossThreadWeakPersistent(watcher), result)); 149 wrapCrossThreadWeakPersistent(watcher), result));
112 } 150 }
113 151
114 void MojoWatcher::runReadyCallback(MojoResult result) { 152 void MojoWatcher::runReadyCallback(MojoResult result) {
153 if (result == MOJO_RESULT_CANCELLED) {
154 // Last notification.
155 m_handle = mojo::Handle();
156
157 // Only dispatch to the callback if this cancellation was implicit due to
158 // |m_handle| closure. If it was explicit, |m_watcherHandle| has already
159 // been reset.
160 if (m_watcherHandle.is_valid()) {
161 m_watcherHandle.reset();
162 runWatchCallback(m_callback, this, result);
163 }
164 return;
165 }
166
115 // Ignore callbacks if not watching. 167 // Ignore callbacks if not watching.
116 if (!m_handle.is_valid()) 168 if (!m_watcherHandle.is_valid())
117 return; 169 return;
118 170
119 // MOJO_RESULT_CANCELLED indicates that the handle has been closed, in which 171 runWatchCallback(m_callback, this, result);
120 // case watch has been implicitly cancelled. There is no need to explicitly
121 // cancel the watch.
122 if (result == MOJO_RESULT_CANCELLED)
123 m_handle = mojo::Handle();
124 172
125 runWatchCallback(m_callback, this, result); 173 // Rearm the watcher so another notification can fire.
174 //
175 // TODO(rockot): MojoWatcher should expose some better approximation of the
176 // new watcher API, including explicit add and removal of handles from the
177 // watcher, as well as explicit arming.
178 MojoResult readyResult;
179 MojoResult armResult = arm(&readyResult);
180 if (armResult == MOJO_RESULT_OK)
181 return;
182
183 DCHECK_EQ(MOJO_RESULT_FAILED_PRECONDITION, armResult);
184
185 m_taskRunner->postTask(BLINK_FROM_HERE,
186 WTF::bind(&MojoWatcher::runReadyCallback,
187 wrapWeakPersistent(this), readyResult));
126 } 188 }
127 189
128 } // namespace blink 190 } // namespace blink
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