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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "third_party/blink/renderer/platform/bindings/active_script_wrappable_manager.h"
#include "third_party/blink/renderer/platform/bindings/active_script_wrappable_base.h"
#include "third_party/blink/renderer/platform/heap/garbage_collected.h"
#include "third_party/blink/renderer/platform/heap/thread_state_scopes.h"
#include "third_party/blink/renderer/platform/wtf/wtf_size_t.h"
namespace blink {
namespace {
bool ScriptWrappableIsActive(const ActiveScriptWrappableBase& asw) {
// A wrapper isn't kept alive after its ExecutionContext becomes detached,
// even if |HasPendingActivity()| returns |true|. This measure avoids
// memory leaks and has proven not to be too eager wrt garbage collection
// of objects belonging to discarded browser contexts (
// https://html.spec.whatwg.org/C/#a-browsing-context-is-discarded )
//
// Consequently, an implementation of |HasPendingActivity()| is not
// required to take the detached state of the associated ExecutionContext
// into account (i.e., return |false|.) We probe the detached state of the
// ExecutionContext via |IsContextDestroyed()|.
if (asw.IsContextDestroyed())
return false;
return asw.HasPendingActivity();
}
} // namespace
void ActiveScriptWrappableManager::RecomputeActiveScriptWrappables(
RecomputeMode mode) {
if (mode == RecomputeMode::kOpportunistic && recomputed_cnt_ > 0)
return;
ThreadState::NoAllocationScope no_allocations(ThreadState::Current());
for (auto& pair : active_script_wrappables_) {
pair.second =
ScriptWrappableIsActive(*pair.first) ? pair.first.Get() : nullptr;
}
recomputed_cnt_++;
}
void ActiveScriptWrappableManager::
CleanupInactiveAndClearActiveScriptWrappables(
const LivenessBroker& broker) {
active_script_wrappables_.erase(
std::remove_if(
active_script_wrappables_.begin(), active_script_wrappables_.end(),
[broker](auto& pair) {
// If the ASW is not alive, the Member reference must be nullptr.
DCHECK(broker.IsHeapObjectAlive(pair.first) || !pair.second);
return !broker.IsHeapObjectAlive(pair.first);
}),
active_script_wrappables_.end());
recomputed_cnt_ = 0;
}
void ActiveScriptWrappableManager::Trace(Visitor* visitor) const {
visitor->Trace(active_script_wrappables_);
visitor->RegisterWeakCallbackMethod<
ActiveScriptWrappableManager,
&ActiveScriptWrappableManager::
CleanupInactiveAndClearActiveScriptWrappables>(this);
}
} // namespace blink
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