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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 */
#ifndef mozilla_dom_cache_Context_h
#define mozilla_dom_cache_Context_h
#include "mozilla/dom/SafeRefPtr.h"
#include "mozilla/dom/cache/Types.h"
#include "nsCOMPtr.h"
#include "nsISupportsImpl.h"
#include "nsProxyRelease.h"
#include "nsString.h"
#include "nsTArray.h"
#include "nsTObserverArray.h"
class nsIEventTarget;
class nsIThread;
namespace mozilla::dom {
namespace quota {
class DirectoryLock;
} // namespace quota
namespace cache {
class Action;
class Manager;
// The Context class is RAII-style class for managing IO operations within the
// Cache.
// When a Context is created it performs the complicated steps necessary to
// initialize the QuotaManager. Action objects dispatched on the Context are
// delayed until this initialization is complete. They are then allow to
// execute on any specified thread. Once all references to the Context are
// gone, then the steps necessary to release the QuotaManager are performed.
// After initialization the Context holds a self reference, so it will stay
// alive until one of three conditions occur:
// 1) The Manager will call Context::AllowToClose() when all of the actors
// have removed themselves as listener. This means an idle context with
// no active DOM objects will close gracefully.
// 2) The QuotaManager aborts all operations so it can delete the files.
// In this case the QuotaManager calls Client::AbortOperationsForLocks()
// which in turn cancels all existing Action objects and then marks the
// Manager as invalid.
// 3) Browser shutdown occurs and the Manager calls Context::CancelAll().
// In either case, though, the Action objects must be destroyed first to
// allow the Context to be destroyed.
// While the Context performs operations asynchronously on threads, all of
// methods in its public interface must be called on the same thread
// originally used to create the Context.
// As an invariant, all Context objects must be destroyed before permitting
// the "profile-before-change" shutdown event to complete. This is ensured
// via the code in ShutdownObserver.cpp.
class Context final : public SafeRefCounted<Context> {
using DirectoryLock = mozilla::dom::quota::DirectoryLock;
// Define a class allowing other threads to hold the Context alive. This also
// allows these other threads to safely close or cancel the Context.
class ThreadsafeHandle final : public AtomicSafeRefCounted<ThreadsafeHandle> {
friend class Context;
explicit ThreadsafeHandle(SafeRefPtr<Context> aContext);
void AllowToClose();
void InvalidateAndAllowToClose();
void AllowToCloseOnOwningThread();
void InvalidateAndAllowToCloseOnOwningThread();
void ContextDestroyed(Context& aContext);
// Cleared to allow the Context to close. Only safe to access on
// owning thread.
SafeRefPtr<Context> mStrongRef;
// Used to support cancelation even while the Context is already allowed
// to close. Cleared by ~Context() calling ContextDestroyed(). Only
// safe to access on owning thread.
Context* mWeakRef;
nsCOMPtr<nsISerialEventTarget> mOwningEventTarget;
// Different objects hold references to the Context while some work is being
// performed asynchronously. These objects must implement the Activity
// interface and register themselves with the AddActivity(). When they are
// destroyed they must call RemoveActivity(). This allows the Context to
// cancel any outstanding Activity work when the Context is cancelled.
class Activity {
virtual void Cancel() = 0;
virtual bool MatchesCacheId(CacheId aCacheId) const = 0;
// Create a Context attached to the given Manager. The given Action
// will run on the QuotaManager IO thread. Note, this Action must
// be execute synchronously.
static SafeRefPtr<Context> Create(SafeRefPtr<Manager> aManager,
nsISerialEventTarget* aTarget,
SafeRefPtr<Action> aInitAction,
Maybe<Context&> aOldContext);
// Execute given action on the target once the quota manager has been
// initialized.
// Only callable from the thread that created the Context.
void Dispatch(SafeRefPtr<Action> aAction);
Maybe<DirectoryLock&> MaybeDirectoryLockRef() const;
// Cancel any Actions running or waiting to run. This should allow the
// Context to be released and Listener::RemoveContext() will be called
// when complete.
// Only callable from the thread that created the Context.
void CancelAll();
// True if CancelAll() has been called.
bool IsCanceled() const;
// Like CancelAll(), but also marks the Manager as "invalid".
void Invalidate();
// Remove any self references and allow the Context to be released when
// there are no more Actions to process.
void AllowToClose();
// Cancel any Actions running or waiting to run that operate on the given
// cache ID.
// Only callable from the thread that created the Context.
void CancelForCacheId(CacheId aCacheId);
void AddActivity(Activity& aActivity);
void RemoveActivity(Activity& aActivity);
// Tell the Context that some state information has been orphaned in the
// data store and won't be cleaned up. The Context will leave the marker
// in place to trigger cleanup the next times its opened.
void NoteOrphanedData();
class Data;
class QuotaInitRunnable;
class ActionRunnable;
enum State {
struct PendingAction {
nsCOMPtr<nsIEventTarget> mTarget;
SafeRefPtr<Action> mAction;
void Init(Maybe<Context&> aOldContext);
void Start();
void DispatchAction(SafeRefPtr<Action> aAction, bool aDoomData = false);
void OnQuotaInit(nsresult aRv,
const Maybe<CacheDirectoryMetadata>& aDirectoryMetadata,
already_AddRefed<DirectoryLock> aDirectoryLock);
SafeRefPtr<ThreadsafeHandle> CreateThreadsafeHandle();
void SetNextContext(SafeRefPtr<Context> aNextContext);
void DoomTargetData();
SafeRefPtr<Manager> mManager;
nsCOMPtr<nsISerialEventTarget> mTarget;
RefPtr<Data> mData;
State mState;
bool mOrphanedData;
Maybe<CacheDirectoryMetadata> mDirectoryMetadata;
RefPtr<QuotaInitRunnable> mInitRunnable;
SafeRefPtr<Action> mInitAction;
nsTArray<PendingAction> mPendingActions;
// Weak refs since activites must remove themselves from this list before
// being destroyed by calling RemoveActivity().
nsTObserverArray<NotNull<Activity*>> mActivityList;
// The ThreadsafeHandle may have a strong ref back to us. This creates
// a ref-cycle that keeps the Context alive. The ref-cycle is broken
// when ThreadsafeHandle::AllowToClose() is called.
SafeRefPtr<ThreadsafeHandle> mThreadsafeHandle;
RefPtr<DirectoryLock> mDirectoryLock;
SafeRefPtr<Context> mNextContext;
// XXX Consider adding a private guard parameter.
Context(SafeRefPtr<Manager> aManager, nsISerialEventTarget* aTarget,
SafeRefPtr<Action> aInitAction);
} // namespace cache
} // namespace mozilla::dom
#endif // mozilla_dom_cache_Context_h