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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_serviceworkerlifetimeextension_h
#define mozilla_dom_serviceworkerlifetimeextension_h
#include "mozilla/TimeStamp.h"
#include "mozilla/Variant.h"
namespace mozilla::dom {
// Do not extend the ServiceWorker's lifetime. This should only be used for
// special internal cases like sending a termination op. If you are thinking
// of using this for other purposes, you probably should not be using the
// ServiceWorkerOp mechanism.
struct NoLifetimeExtension {};
// Propagated lifetime extension allows us to ensure that a ServiceWorker
// using ServiceWorker.postMessage to contact another ServiceWorker cannot
// extend the lifetime of the recipient ServiceWorker beyond the lifetime of
// the sender.
struct PropagatedLifetimeExtension {
// We propagate the lifetime as a timestamp-as-deadline rather than a
// duration because a duration is effectively frozen in time until it is
// applied, providing potential for abuse due to the inherently async nature
// of the events involved.
//
// It is possible for this value to be in the past by the time it is
// processed. It is also possible for this value to be null because of
// async delays between the transmission of a message from one ServiceWorker
// (in the content process) and the time it is received in the parent
// process and/or because the sending ServiceWorker has reached its deadline
// but is in its "grace period". We do not attempt to normalize these cases
// into `NoLifetimeExtension`.
TimeStamp mDeadline;
};
// For functional events that are initiated by window clients or very specific
// APIs like the Push API where care has been taken to ensure that Service
// Workers can only run without having a tab open under very specific
// circumstances that have been extensively discussed with the standards,
// privacy, and security teams.
struct FullLifetimeExtension {};
/**
* Conveys how events dispatched at a Service Worker global should impact its
* lifetime.
*/
struct ServiceWorkerLifetimeExtension
: public Variant<NoLifetimeExtension, PropagatedLifetimeExtension,
FullLifetimeExtension> {
public:
explicit ServiceWorkerLifetimeExtension(NoLifetimeExtension aExt)
: Variant(AsVariant(std::move(aExt))) {}
explicit ServiceWorkerLifetimeExtension(PropagatedLifetimeExtension aExt)
: Variant(AsVariant(std::move(aExt))) {}
explicit ServiceWorkerLifetimeExtension(FullLifetimeExtension aExt)
: Variant(AsVariant(std::move(aExt))) {}
// Check whether this lifetime extends at least the provided number of
// seconds into the future. This is for use in situations where we might
// freshly spawn a new ServiceWorker like `SpawnWorkerIfNeeded`. This helps
// compensate for the fixed costs to spawning a ServiceWorker as well as the
// assumption that a ServiceWorker needs at least a minimum amount of run time
// to accomplish something. Note that a spawned ServiceWorker will still
// potentially be able to leverage the
// "dom.serviceWorkers.idle_extended_timeout" grace period, which with current
// pref values means an extra 30 seconds of potential execution time. (But
// the grace period never counts for propagated deadline purposes.)
bool LifetimeExtendsIntoTheFuture(uint32_t aRequiredSecs = 5) const;
};
} // namespace mozilla::dom
#endif // mozilla_dom_serviceworkerlifetimeextension_h
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