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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_serviceworkershutdownblocker_h__
#define mozilla_dom_serviceworkershutdownblocker_h__
#include "nsCOMPtr.h"
#include "nsIAsyncShutdown.h"
#include "nsISupportsImpl.h"
#include "nsITimer.h"
#include "ServiceWorkerShutdownState.h"
#include "mozilla/MozPromise.h"
#include "mozilla/HashTable.h"
namespace mozilla {
namespace dom {
/**
* Main thread only.
*
* A ServiceWorkerShutdownBlocker will "accept promises", and each of these
* promises will be a "pending promise" while it hasn't settled. At some point,
* `StopAcceptingPromises()` should be called and the state will change to "not
* accepting promises" (this is a one way state transition). The shutdown phase
* of the shutdown client the blocker is created with will be blocked until
* there are no more pending promises.
*
* It doesn't matter whether the state changes to "not accepting promises"
* before or during the associated shutdown phase.
*
* In beta/release builds there will be an additional timer that starts ticking
* once both the shutdown phase has been reached and the state is "not accepting
* promises". If when the timer expire there are still pending promises,
* shutdown will be forcefully unblocked.
*/
class ServiceWorkerShutdownBlocker final : public nsIAsyncShutdownBlocker,
public nsITimerCallback {
public:
using Progress = ServiceWorkerShutdownState::Progress;
static const uint32_t kInvalidShutdownStateId = 0;
NS_DECL_ISUPPORTS
NS_DECL_NSIASYNCSHUTDOWNBLOCKER
NS_DECL_NSITIMERCALLBACK
/**
* Returns the registered shutdown blocker if registration succeeded and
* nullptr otherwise.
*/
static already_AddRefed<ServiceWorkerShutdownBlocker> CreateAndRegisterOn(
nsIAsyncShutdownClient* aShutdownBarrier);
/**
* Blocks shutdown until `aPromise` settles.
*
* Can be called multiple times, and shutdown will be blocked until all the
* calls' promises settle, but all of these calls must happen before
* `StopAcceptingPromises()` is called (assertions will enforce this).
*
* See `CreateShutdownState` for aShutdownStateId, which is needed to clear
* the shutdown state if the shutdown process aborts for some reason.
*/
void WaitOnPromise(GenericNonExclusivePromise* aPromise,
uint32_t aShutdownStateId);
/**
* Once this is called, shutdown will be blocked until all promises
* passed to `WaitOnPromise()` settle, and there must be no more calls to
* `WaitOnPromise()` (assertions will enforce this).
*/
void StopAcceptingPromises();
/**
* Start tracking the shutdown of an individual ServiceWorker for hang
* reporting purposes. Returns a "shutdown state ID" that should be used
* in subsequent calls to ReportShutdownProgress. The shutdown of an
* individual ServiceWorker is presumed to be completed when its `Progress`
* reaches `Progress::ShutdownCompleted`.
*/
uint32_t CreateShutdownState();
void ReportShutdownProgress(uint32_t aShutdownStateId, Progress aProgress);
private:
ServiceWorkerShutdownBlocker();
~ServiceWorkerShutdownBlocker();
/**
* No-op if any of the following are true:
* 1) `BlockShutdown()` hasn't been called yet, or
* 2) `StopAcceptingPromises()` hasn't been called yet, or
* 3) `StopAcceptingPromises()` HAS been called, but there are still pending
* promises.
*/
void MaybeUnblockShutdown();
/**
* Requires `BlockShutdown()` to have been called.
*/
void UnblockShutdown();
/**
* Returns the remaining pending promise count (i.e. excluding the promise
* that just settled).
*/
uint32_t PromiseSettled();
bool IsAcceptingPromises() const;
uint32_t GetPendingPromises() const;
/**
* Initializes a timer that will unblock shutdown unconditionally once it's
* expired (even if there are still pending promises). No-op if:
* 1) not a beta or release build, or
* 2) shutdown is not being blocked or `StopAcceptingPromises()` has not been
* called.
*/
void MaybeInitUnblockShutdownTimer();
struct AcceptingPromises {
uint32_t mPendingPromises = 0;
};
struct NotAcceptingPromises {
explicit NotAcceptingPromises(AcceptingPromises aPreviousState);
uint32_t mPendingPromises = 0;
};
Variant<AcceptingPromises, NotAcceptingPromises> mState;
nsCOMPtr<nsIAsyncShutdownClient> mShutdownClient;
HashMap<uint32_t, ServiceWorkerShutdownState> mShutdownStates;
nsCOMPtr<nsITimer> mTimer;
};
} // namespace dom
} // namespace mozilla
#endif // mozilla_dom_serviceworkershutdownblocker_h__