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// Copyright 2018 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 "third_party/blink/renderer/core/dom/abort_signal.h"
#include <utility>
#include "base/callback.h"
#include "third_party/blink/renderer/core/dom/events/event.h"
#include "third_party/blink/renderer/core/event_target_names.h"
#include "third_party/blink/renderer/core/event_type_names.h"
#include "third_party/blink/renderer/platform/heap/visitor.h"
#include "third_party/blink/renderer/platform/wtf/text/atomic_string.h"
namespace blink {
AbortSignal::AbortSignal(ExecutionContext* execution_context)
: execution_context_(execution_context) {}
AbortSignal::~AbortSignal() = default;
const AtomicString& AbortSignal::InterfaceName() const {
return EventTargetNames::AbortSignal;
}
ExecutionContext* AbortSignal::GetExecutionContext() const {
return execution_context_.Get();
}
void AbortSignal::AddAlgorithm(base::OnceClosure algorithm) {
if (aborted_flag_)
return;
abort_algorithms_.push_back(std::move(algorithm));
}
void AbortSignal::SignalAbort() {
if (aborted_flag_)
return;
aborted_flag_ = true;
for (base::OnceClosure& closure : abort_algorithms_) {
std::move(closure).Run();
}
abort_algorithms_.clear();
DispatchEvent(Event::Create(EventTypeNames::abort));
}
void AbortSignal::Follow(AbortSignal* parentSignal) {
if (aborted_flag_)
return;
if (parentSignal->aborted_flag_)
SignalAbort();
// Unlike the usual practice for AddAlgorithm(), we don't use a weak pointer
// here. To see why, consider the following object graph:
//
// controller --owns--> signal1 -?-> signal2 -?-> signal3 <--owns-- request
//
// It's easy to create chained signals like this using the Request
// constructor. If the -?-> pointers were weak, then |signal2| could be
// collected even though |controller| and |request| were still
// referenced. This would prevent controller.abort() from working. So the
// pointers need to be strong. This won't artificially extend the lifetime of
// |request|, because the pointer to it in the closure held by |signal3| is
// still weak.
parentSignal->AddAlgorithm(
WTF::Bind(&AbortSignal::SignalAbort, WrapPersistent(this)));
}
void AbortSignal::Trace(Visitor* visitor) {
visitor->Trace(execution_context_);
EventTargetWithInlineData::Trace(visitor);
}
} // namespace blink
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