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diff --git a/dom/cache/Action.h b/dom/cache/Action.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_Action_h
+#define mozilla_dom_cache_Action_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/dom/cache/Types.h"
+#include "nsISupportsImpl.h"
+
+class mozIStorageConnection;
+
+namespace mozilla {
+namespace dom {
+namespace cache {
+
+class Action
+{
+public:
+ class Resolver
+ {
+ public:
+ // Note: Action must drop Resolver ref after calling Resolve()!
+ // Note: Must be called on the same thread used to execute
+ // Action::RunOnTarget().
+ virtual void Resolve(nsresult aRv) = 0;
+
+ NS_IMETHOD_(MozExternalRefCountType)
+ AddRef(void) = 0;
+
+ NS_IMETHOD_(MozExternalRefCountType)
+ Release(void) = 0;
+ };
+
+ // Class containing data that can be opportunistically shared between
+ // multiple Actions running on the same thread/Context. In theory
+ // this could be abstracted to a generic key/value map, but for now
+ // just explicitly provide accessors for the data we need.
+ class Data
+ {
+ public:
+ virtual mozIStorageConnection*
+ GetConnection() const = 0;
+
+ virtual void
+ SetConnection(mozIStorageConnection* aConn) = 0;
+ };
+
+ // Execute operations on the target thread. Once complete call
+ // Resolver::Resolve(). This can be done sync or async.
+ // Note: Action should hold Resolver ref until its ready to call Resolve().
+ // Note: The "target" thread is determined when the Action is scheduled on
+ // Context. The Action should not assume any particular thread is used.
+ virtual void RunOnTarget(Resolver* aResolver, const QuotaInfo& aQuotaInfo,
+ Data* aOptionalData) = 0;
+
+ // Called on initiating thread when the Action is canceled. The Action is
+ // responsible for calling Resolver::Resolve() as normal; either with a
+ // normal error code or NS_ERROR_ABORT. If CancelOnInitiatingThread() is
+ // called after Resolve() has already occurred, then the cancel can be
+ // ignored.
+ //
+ // Cancellation is a best effort to stop processing as soon as possible, but
+ // does not guarantee the Action will not run.
+ //
+ // CancelOnInitiatingThread() may be called more than once. Subsequent
+ // calls should have no effect.
+ //
+ // Default implementation sets an internal cancellation flag that can be
+ // queried with IsCanceled().
+ virtual void CancelOnInitiatingThread();
+
+ // Executed on the initiating thread and is passed the nsresult given to
+ // Resolver::Resolve().
+ virtual void CompleteOnInitiatingThread(nsresult aRv) { }
+
+ // Executed on the initiating thread. If this Action will operate on the
+ // given cache ID then override this to return true.
+ virtual bool MatchesCacheId(CacheId aCacheId) const { return false; }
+
+ NS_INLINE_DECL_REFCOUNTING(cache::Action)
+
+protected:
+ Action();
+
+ // virtual because deleted through base class pointer
+ virtual ~Action();
+
+ // Check if this Action has been canceled. May be called from any thread,
+ // but typically used from the target thread.
+ bool IsCanceled() const;
+
+private:
+ // Accessible from any thread.
+ Atomic<bool> mCanceled;
+};
+
+} // namespace cache
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_cache_Action_h