ppapi/shared_impl/tracked_callback.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 "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
  25 bool IsMainThread() {
  26   return
  27       PpapiGlobals::Get()->GetMainThreadMessageLoop()->BelongsToCurrentThread();
  28 }
  29
  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.
  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
  83 TrackedCallback::~TrackedCallback() {
  84 }
  85
  86 void TrackedCallback::Abort() {
  87   Run(PP_ERROR_ABORTED);
  88 }
  89
  90 void TrackedCallback::PostAbort() {
  91   PostRun(PP_ERROR_ABORTED);
  92 }
  93
  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
 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
 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
 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
 205 bool TrackedCallback::IsScheduledToRun(
 206     const scoped_refptr<TrackedCallback>& callback) {
 207   return IsPending(callback) && callback->is_scheduled_;
 208 }
 209
 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
 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