1 files changed, 235 insertions, 0 deletions
diff --git a/dom/cache/Context.h b/dom/cache/Context.h
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+++ b/dom/cache/Context.h
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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_cache_Context_h
+#define mozilla_dom_cache_Context_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 {
+namespace 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::AbortOperations() 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
+{
+  typedef mozilla::dom::quota::DirectoryLock DirectoryLock;
+
+public:
+  // 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
+  {
+    friend class Context;
+  public:
+    void AllowToClose();
+    void InvalidateAndAllowToClose();
+  private:
+    explicit ThreadsafeHandle(Context* aContext);
+    ~ThreadsafeHandle();
+
+    // disallow copying
+    ThreadsafeHandle(const ThreadsafeHandle&) = delete;
+    ThreadsafeHandle& operator=(const ThreadsafeHandle&) = delete;
+
+    void AllowToCloseOnOwningThread();
+    void InvalidateAndAllowToCloseOnOwningThread();
+
+    void ContextDestroyed(Context* aContext);
+
+    // Cleared to allow the Context to close.  Only safe to access on
+    // owning thread.
+    RefPtr<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<nsIThread> mOwningThread;
+
+    NS_INLINE_DECL_THREADSAFE_REFCOUNTING(cache::Context::ThreadsafeHandle)
+  };
+
+  // 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
+  {
+  public:
+    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 already_AddRefed<Context>
+  Create(Manager* aManager, nsIThread* aTarget,
+         Action* aInitAction, 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(Action* aAction);
+
+  // 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);
+
+  const QuotaInfo&
+  GetQuotaInfo() const
+  {
+    return mQuotaInfo;
+  }
+
+  // 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();
+
+private:
+  class Data;
+  class QuotaInitRunnable;
+  class ActionRunnable;
+
+  enum State
+  {
+    STATE_CONTEXT_PREINIT,
+    STATE_CONTEXT_INIT,
+    STATE_CONTEXT_READY,
+    STATE_CONTEXT_CANCELED
+  };
+
+  struct PendingAction
+  {
+    nsCOMPtr<nsIEventTarget> mTarget;
+    RefPtr<Action> mAction;
+  };
+
+  Context(Manager* aManager, nsIThread* aTarget, Action* aInitAction);
+  ~Context();
+  void Init(Context* aOldContext);
+  void Start();
+  void DispatchAction(Action* aAction, bool aDoomData = false);
+  void OnQuotaInit(nsresult aRv, const QuotaInfo& aQuotaInfo,
+                   already_AddRefed<DirectoryLock> aDirectoryLock);
+
+
+  already_AddRefed<ThreadsafeHandle>
+  CreateThreadsafeHandle();
+
+  void
+  SetNextContext(Context* aNextContext);
+
+  void
+  DoomTargetData();
+
+  RefPtr<Manager> mManager;
+  nsCOMPtr<nsIThread> mTarget;
+  RefPtr<Data> mData;
+  State mState;
+  bool mOrphanedData;
+  QuotaInfo mQuotaInfo;
+  RefPtr<QuotaInitRunnable> mInitRunnable;
+  RefPtr<Action> mInitAction;
+  nsTArray<PendingAction> mPendingActions;
+
+  // Weak refs since activites must remove themselves from this list before
+  // being destroyed by calling RemoveActivity().
+  typedef nsTObserverArray<Activity*> ActivityList;
+  ActivityList 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.
+  RefPtr<ThreadsafeHandle> mThreadsafeHandle;
+
+  RefPtr<DirectoryLock> mDirectoryLock;
+  RefPtr<Context> mNextContext;
+
+public:
+  NS_INLINE_DECL_REFCOUNTING(cache::Context)
+};
+
+} // namespace cache
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_cache_Context_h