Properly cancel PPAPI callbacks.

This sets up infrastructure to properly cancel PPAPI callbacks (which have particular semantics), and converts a couple things to use them.

BUG=
TEST=test_shell_tests and PPAPI tests

Review URL: http://codereview.chromium.org/5562008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69773 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 155 insertions, 0 deletions

diff --git a/webkit/plugins/ppapi/callbacks.cc b/webkit/plugins/ppapi/callbacks.cc
new file mode 100644
index 0000000..69cd2e8
--- /dev/null
+++ b/webkit/plugins/ppapi/callbacks.cc
@@ -0,0 +1,155 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "webkit/plugins/ppapi/callbacks.h"
+
+#include <algorithm>
+
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "ppapi/c/pp_completion_callback.h"
+#include "ppapi/c/pp_errors.h"
+
+namespace webkit {
+namespace ppapi {
+
+// CallbackTracker -------------------------------------------------------------
+
+CallbackTracker::CallbackTracker() {
+}
+
+void CallbackTracker::AbortAll() {
+  // Iterate over a copy since |Abort()| calls |Remove()| (indirectly).
+  // TODO(viettrungluu): This obviously isn't so efficient.
+  CallbackSetMap pending_callbacks_copy = pending_callbacks_;
+  for (CallbackSetMap::iterator it1 = pending_callbacks_copy.begin();
+       it1 != pending_callbacks_copy.end(); ++it1) {
+    for (CallbackSet::iterator it2 = it1->second.begin();
+         it2 != it1->second.end(); ++it2) {
+      (*it2)->Abort();
+    }
+  }
+}
+
+void CallbackTracker::PostAbortForResource(PP_Resource resource_id) {
+  CHECK(resource_id != 0);
+  CallbackSetMap::iterator it1 = pending_callbacks_.find(resource_id);
+  if (it1 == pending_callbacks_.end())
+    return;
+  for (CallbackSet::iterator it2 = it1->second.begin();
+       it2 != it1->second.end(); ++it2) {
+    // Post the abort.
+    (*it2)->PostAbort();
+  }
+}
+
+CallbackTracker::~CallbackTracker() {
+  // All callbacks must be aborted before destruction.
+  CHECK_EQ(0u, pending_callbacks_.size());
+}
+
+void CallbackTracker::Add(
+    const scoped_refptr<TrackedCallback>& tracked_callback) {
+  PP_Resource resource_id = tracked_callback->resource_id();
+  DCHECK(pending_callbacks_[resource_id].find(tracked_callback) ==
+         pending_callbacks_[resource_id].end());
+  pending_callbacks_[resource_id].insert(tracked_callback);
+}
+
+void CallbackTracker::Remove(
+    const scoped_refptr<TrackedCallback>& tracked_callback) {
+  CallbackSetMap::iterator map_it =
+      pending_callbacks_.find(tracked_callback->resource_id());
+  DCHECK(map_it != pending_callbacks_.end());
+  CallbackSet::iterator it = map_it->second.find(tracked_callback);
+  DCHECK(it != map_it->second.end());
+  map_it->second.erase(it);
+
+  // If there are no pending callbacks left for this ID, get rid of the entry.
+  if (map_it->second.empty())
+    pending_callbacks_.erase(map_it);
+}
+
+// TrackedCallback -------------------------------------------------------------
+
+TrackedCallback::TrackedCallback(const scoped_refptr<CallbackTracker>& tracker,
+                                 PP_Resource resource_id)
+    : ALLOW_THIS_IN_INITIALIZER_LIST(abort_impl_factory_(this)),
+      tracker_(tracker),
+      resource_id_(resource_id),
+      completed_(false),
+      aborted_(false) {
+  tracker_->Add(make_scoped_refptr(this));
+}
+
+void TrackedCallback::Abort() {
+  if (!completed()) {
+    aborted_ = true;
+    AbortImpl();
+  }
+}
+
+void TrackedCallback::PostAbort() {
+  if (!completed()) {
+    aborted_ = true;
+    // Post a task for the abort (only if necessary).
+    if (abort_impl_factory_.empty()) {
+      MessageLoop::current()->PostTask(
+          FROM_HERE,
+          abort_impl_factory_.NewRunnableMethod(&TrackedCallback::AbortImpl));
+    }
+  }
+}
+
+TrackedCallback::~TrackedCallback() {
+  // The tracker must ensure that the callback is completed (maybe abortively).
+  DCHECK(completed_);
+}
+
+void TrackedCallback::MarkAsCompleted() {
+  DCHECK(!completed());
+
+  // We will be removed; maintain a reference to ensure we won't be deleted
+  // until we're done.
+  scoped_refptr<TrackedCallback> thiz = this;
+  completed_ = true;
+  tracker_->Remove(thiz);
+  tracker_ = NULL;
+}
+
+// TrackedCompletionCallback ---------------------------------------------------
+
+TrackedCompletionCallback::TrackedCompletionCallback(
+    const scoped_refptr<CallbackTracker>& tracker,
+    PP_Resource resource_id,
+    const PP_CompletionCallback& callback)
+    : TrackedCallback(tracker, resource_id),
+      callback_(callback) {
+}
+
+void TrackedCompletionCallback::Run(int32_t result) {
+  if (!completed()) {
+    // Cancel any pending calls.
+    abort_impl_factory_.RevokeAll();
+
+    // Copy |callback_| and look at |aborted()| now, since |MarkAsCompleted()|
+    // may delete us.
+    PP_CompletionCallback callback = callback_;
+    if (aborted())
+      result = PP_ERROR_ABORTED;
+
+    // Do this before running the callback in case of reentrancy (which
+    // shouldn't happen, but avoid strange failures).
+    MarkAsCompleted();
+    PP_RunCompletionCallback(&callback, result);
+  }
+}
+
+void TrackedCompletionCallback::AbortImpl() {
+  Run(PP_ERROR_ABORTED);
+}
+
+}  // namespace ppapi
+}  // namespace webkit