// Copyright 2017 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.

#ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_LOCKS_LOCK_MANAGER_H_
#define THIRD_PARTY_BLINK_RENDERER_MODULES_LOCKS_LOCK_MANAGER_H_

#include "third_party/blink/public/platform/modules/locks/lock_manager.mojom-blink.h"
#include "third_party/blink/renderer/bindings/core/v8/string_or_string_sequence.h"
#include "third_party/blink/renderer/modules/locks/lock.h"
#include "third_party/blink/renderer/modules/locks/lock_options.h"
#include "third_party/blink/renderer/modules/modules_export.h"
#include "third_party/blink/renderer/platform/bindings/script_wrappable.h"
#include "third_party/blink/renderer/platform/heap/heap_allocator.h"

namespace blink {

class ScriptPromise;
class ScriptState;
class V8LockGrantedCallback;

class LockManager final : public ScriptWrappable,
                          public ContextLifecycleObserver {
  WTF_MAKE_NONCOPYABLE(LockManager);
  DEFINE_WRAPPERTYPEINFO();
  USING_GARBAGE_COLLECTED_MIXIN(LockManager);

 public:
  explicit LockManager(ExecutionContext*);

  ScriptPromise request(ScriptState*,
                        const String& name,
                        V8LockGrantedCallback*,
                        ExceptionState&);
  ScriptPromise request(ScriptState*,
                        const String& name,
                        const LockOptions*,
                        V8LockGrantedCallback*,
                        ExceptionState&);

  ScriptPromise query(ScriptState*, ExceptionState&);

  void Trace(blink::Visitor*) override;

  // Terminate all outstanding requests when the context is destroyed, since
  // this can unblock requests by other contexts.
  void ContextDestroyed(ExecutionContext*) override;

  // Called by a lock when it is released. The lock is dropped from the
  // |held_locks_| list. Held locks are tracked until explicitly released (or
  // context is destroyed) to handle the case where both the lock and the
  // promise holding it open have no script references and are potentially
  // collectable. In that case, the lock should be held until the context
  // is destroyed. See https://crbug.com/798500 for an example.
  void OnLockReleased(Lock*);

 private:
  class LockRequestImpl;

  // Track pending requests so that they can be cancelled if the context is
  // terminated.
  void AddPendingRequest(LockRequestImpl*);
  void RemovePendingRequest(LockRequestImpl*);
  bool IsPendingRequest(LockRequestImpl*);

  HeapHashSet<TraceWrapperMember<LockRequestImpl>> pending_requests_;
  HeapHashSet<Member<Lock>> held_locks_;

  mojom::blink::LockManagerPtr service_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_MODULES_LOCKS_LOCK_MANAGER_H_