/* -*- 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_INLINE_DECL_PURE_VIRTUAL_REFCOUNTING

  };

  // 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