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 "ppapi/shared_impl/tracked_callback.h"
6
7 #include "base/bind.h"
8 #include "base/compiler_specific.h"
9 #include "base/logging.h"
10 #include "base/message_loop/message_loop.h"
11 #include "base/synchronization/lock.h"
12 #include "ppapi/c/pp_completion_callback.h"
13 #include "ppapi/c/pp_errors.h"
14 #include "ppapi/c/ppb_message_loop.h"
15 #include "ppapi/shared_impl/callback_tracker.h"
16 #include "ppapi/shared_impl/ppapi_globals.h"
17 #include "ppapi/shared_impl/ppb_message_loop_shared.h"
18 #include "ppapi/shared_impl/proxy_lock.h"
19 #include "ppapi/shared_impl/resource.h"
20
21 namespace ppapi {
22
23 namespace {
24
IsMainThread()25 bool IsMainThread() {
26 return
27 PpapiGlobals::Get()->GetMainThreadMessageLoop()->BelongsToCurrentThread();
28 }
29
RunCompletionTask(TrackedCallback::CompletionTask completion_task,int32_t result)30 int32_t RunCompletionTask(TrackedCallback::CompletionTask completion_task,
31 int32_t result) {
32 int32_t task_result = completion_task.Run(result);
33 if (result != PP_ERROR_ABORTED)
34 result = task_result;
35 return result;
36 }
37
38 } // namespace
39
40 // TrackedCallback -------------------------------------------------------------
41
42 // Note: don't keep a Resource* since it may go out of scope before us.
TrackedCallback(Resource * resource,const PP_CompletionCallback & callback)43 TrackedCallback::TrackedCallback(
44 Resource* resource,
45 const PP_CompletionCallback& callback)
46 : is_scheduled_(false),
47 resource_id_(resource ? resource->pp_resource() : 0),
48 completed_(false),
49 aborted_(false),
50 callback_(callback),
51 target_loop_(PpapiGlobals::Get()->GetCurrentMessageLoop()),
52 result_for_blocked_callback_(PP_OK) {
53 // Note that target_loop_ may be NULL at this point, if the plugin has not
54 // attached a loop to this thread, or if this is an in-process plugin.
55 // The Enter class should handle checking this for us.
56
57 // TODO(dmichael): Add tracking at the instance level, for callbacks that only
58 // have an instance (e.g. for MouseLock).
59 if (resource) {
60 tracker_ = PpapiGlobals::Get()->GetCallbackTrackerForInstance(
61 resource->pp_instance());
62 tracker_->Add(make_scoped_refptr(this));
63 }
64
65 base::Lock* proxy_lock = ProxyLock::Get();
66 if (proxy_lock) {
67 // If the proxy_lock is valid, we're running out-of-process, and locking
68 // is enabled.
69 if (is_blocking()) {
70 // This is a blocking completion callback, so we will need a condition
71 // variable for blocking & signalling the calling thread.
72 operation_completed_condvar_.reset(
73 new base::ConditionVariable(proxy_lock));
74 } else {
75 // It's a non-blocking callback, so we should have a MessageLoopResource
76 // to dispatch to. Note that we don't error check here, though. Later,
77 // EnterResource::SetResult will check to make sure the callback is valid
78 // and take appropriate action.
79 }
80 }
81 }
82
~TrackedCallback()83 TrackedCallback::~TrackedCallback() {
84 }
85
Abort()86 void TrackedCallback::Abort() {
87 Run(PP_ERROR_ABORTED);
88 }
89
PostAbort()90 void TrackedCallback::PostAbort() {
91 PostRun(PP_ERROR_ABORTED);
92 }
93
Run(int32_t result)94 void TrackedCallback::Run(int32_t result) {
95 // Only allow the callback to be run once. Note that this also covers the case
96 // where the callback was previously Aborted because its associated Resource
97 // went away. The callback may live on for a while because of a reference from
98 // a Closure. But when the Closure runs, Run() quietly does nothing, and the
99 // callback will go away when all referring Closures go away.
100 if (completed())
101 return;
102 if (result == PP_ERROR_ABORTED)
103 aborted_ = true;
104
105 // Note that this call of Run() may have been scheduled prior to Abort() or
106 // PostAbort() being called. If we have been told to Abort, that always
107 // trumps a result that was scheduled before, so we should make sure to pass
108 // PP_ERROR_ABORTED.
109 if (aborted())
110 result = PP_ERROR_ABORTED;
111
112 if (is_blocking()) {
113 // If the condition variable is invalid, there are two possibilities. One,
114 // we're running in-process, in which case the call should have come in on
115 // the main thread and we should have returned PP_ERROR_BLOCKS_MAIN_THREAD
116 // well before this. Otherwise, this callback was not created as a
117 // blocking callback. Either way, there's some internal error.
118 if (!operation_completed_condvar_.get()) {
119 NOTREACHED();
120 return;
121 }
122 result_for_blocked_callback_ = result;
123 // Retain ourselves, since MarkAsCompleted will remove us from the
124 // tracker. Then MarkAsCompleted before waking up the blocked thread,
125 // which could potentially re-enter.
126 scoped_refptr<TrackedCallback> thiz(this);
127 MarkAsCompleted();
128 // Wake up the blocked thread. See BlockUntilComplete for where the thread
129 // Wait()s.
130 operation_completed_condvar_->Signal();
131 } else {
132 // If there's a target_loop_, and we're not on the right thread, we need to
133 // post to target_loop_.
134 if (target_loop_.get() &&
135 target_loop_.get() != PpapiGlobals::Get()->GetCurrentMessageLoop()) {
136 PostRun(result);
137 return;
138 }
139
140 // Copy callback fields now, since |MarkAsCompleted()| may delete us.
141 PP_CompletionCallback callback = callback_;
142 CompletionTask completion_task = completion_task_;
143 completion_task_.Reset();
144 // Do this before running the callback in case of reentrancy from running
145 // the completion task.
146 MarkAsCompleted();
147
148 if (!completion_task.is_null())
149 result = RunCompletionTask(completion_task, result);
150
151 // TODO(dmichael): Associate a message loop with the callback; if it's not
152 // the same as the current thread's loop, then post it to the right loop.
153 CallWhileUnlocked(PP_RunCompletionCallback, &callback, result);
154 }
155 }
156
PostRun(int32_t result)157 void TrackedCallback::PostRun(int32_t result) {
158 if (completed()) {
159 NOTREACHED();
160 return;
161 }
162 if (result == PP_ERROR_ABORTED)
163 aborted_ = true;
164 // We might abort when there's already a scheduled callback, but callers
165 // should never try to PostRun more than once otherwise.
166 DCHECK(result == PP_ERROR_ABORTED || !is_scheduled_);
167
168 if (is_blocking()) {
169 // We might not have a MessageLoop to post to, so we must call Run()
170 // directly.
171 Run(result);
172 } else {
173 base::Closure callback_closure(
174 RunWhileLocked(base::Bind(&TrackedCallback::Run, this, result)));
175 if (target_loop_) {
176 target_loop_->PostClosure(FROM_HERE, callback_closure, 0);
177 } else {
178 // We must be running in-process and on the main thread (the Enter
179 // classes protect against having a null target_loop_ otherwise).
180 DCHECK(IsMainThread());
181 DCHECK(PpapiGlobals::Get()->IsHostGlobals());
182 base::MessageLoop::current()->PostTask(FROM_HERE, callback_closure);
183 }
184 }
185 is_scheduled_ = true;
186 }
187
set_completion_task(const CompletionTask & completion_task)188 void TrackedCallback::set_completion_task(
189 const CompletionTask& completion_task) {
190 DCHECK(completion_task_.is_null());
191 completion_task_ = completion_task;
192 }
193
194 // static
IsPending(const scoped_refptr<TrackedCallback> & callback)195 bool TrackedCallback::IsPending(
196 const scoped_refptr<TrackedCallback>& callback) {
197 if (!callback.get())
198 return false;
199 if (callback->aborted())
200 return false;
201 return !callback->completed();
202 }
203
204 // static
IsScheduledToRun(const scoped_refptr<TrackedCallback> & callback)205 bool TrackedCallback::IsScheduledToRun(
206 const scoped_refptr<TrackedCallback>& callback) {
207 return IsPending(callback) && callback->is_scheduled_;
208 }
209
BlockUntilComplete()210 int32_t TrackedCallback::BlockUntilComplete() {
211 // Note, we are already holding the proxy lock in all these methods, including
212 // this one (see ppapi/thunk/enter.cc for where it gets acquired).
213
214 // It doesn't make sense to wait on a non-blocking callback. Furthermore,
215 // BlockUntilComplete should never be called for in-process plugins, where
216 // blocking callbacks are not supported.
217 CHECK(operation_completed_condvar_.get());
218 if (!is_blocking() || !operation_completed_condvar_.get()) {
219 NOTREACHED();
220 return PP_ERROR_FAILED;
221 }
222
223 while (!completed())
224 operation_completed_condvar_->Wait();
225
226 if (!completion_task_.is_null()) {
227 result_for_blocked_callback_ =
228 RunCompletionTask(completion_task_, result_for_blocked_callback_);
229 completion_task_.Reset();
230 }
231 return result_for_blocked_callback_;
232 }
233
MarkAsCompleted()234 void TrackedCallback::MarkAsCompleted() {
235 DCHECK(!completed());
236
237 // We will be removed; maintain a reference to ensure we won't be deleted
238 // until we're done.
239 scoped_refptr<TrackedCallback> thiz = this;
240 completed_ = true;
241 // We may not have a valid resource, in which case we're not in the tracker.
242 if (resource_id_)
243 tracker_->Remove(thiz);
244 tracker_ = NULL;
245 }
246
247 } // namespace ppapi
248