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automation_handle_tracker.h

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// This file defines a mapping between Automation Proxy objects and
// their associated app-side handles.

#ifndef CHROME_TEST_AUTOMATION_AUTOMATION_HANDLE_TRACKER_H__
#define CHROME_TEST_AUTOMATION_AUTOMATION_HANDLE_TRACKER_H__

#include <map>

#include "base/basictypes.h"
#include "base/lock.h"
#include "base/ref_counted.h"
#include "ipc/ipc_channel.h"

// This represents a value that the app's AutomationProvider returns
// when asked for a resource (like a window or tab).
typedef int AutomationHandle;

class AutomationHandleTracker;
class AutomationMessageSender;

class AutomationResourceProxy
    : public base::RefCountedThreadSafe<AutomationResourceProxy> {
 public:
  AutomationResourceProxy(AutomationHandleTracker* tracker,
                          AutomationMessageSender* sender,
                          AutomationHandle handle);

  // Marks this proxy object as no longer valid; this generally means
  // that the corresponding resource on the app side is gone.
  void Invalidate() {
    is_valid_ = false;
    tracker_ = NULL;
  }

  bool is_valid() const { return is_valid_; }

  // Returns the handle that the app has generated to refer to this resource.
  AutomationHandle handle() { return handle_; }

 protected:
  friend class AutomationHandleTracker;
  friend class base::RefCountedThreadSafe<AutomationResourceProxy>;

  virtual ~AutomationResourceProxy();

  AutomationHandle handle_;

  // Not owned by us, owned by the AutomationProxy object. May be NULL if the
  // tracker has been destroyed (and hence the object is invalid).
  AutomationHandleTracker* tracker_;

  // Not owned by us.
  AutomationMessageSender* sender_;

 private:
  // True if the resource that this object is a proxy for on the app side
  // still exists.
  bool is_valid_;

  DISALLOW_EVIL_CONSTRUCTORS(AutomationResourceProxy);
};

// This class keeps track of the mapping between AutomationHandles and
// AutomationResourceProxy objects.  This is important because (1) multiple
// AutomationResourceProxy objects can be generated for the same handle
// (2) handles can be invalidated by the app, and all the associated
// proxy objects then need to be invalidated, and (3) when a handle is no
// longer being used on this end, we need to tell the app that it can
// discard the handle.
class AutomationHandleTracker {
 public:
  explicit AutomationHandleTracker() : channel_(NULL) {}
  ~AutomationHandleTracker();

  // Adds the specified proxy object to the tracker.
  void Add(AutomationResourceProxy* proxy);

  // Removes a given proxy object from the mapping, and unregisters the
  // handle on the app side if this was the last proxy object that was using
  // that handle.  This is a no-op if the proxy object is not currently
  // in the tracker.
  void Remove(AutomationResourceProxy* proxy);

  // Marks all proxy objects related to a given handle invalid.  This is
  // used when a resource (like a window) on the app side is closed, meaning
  // that no further operations can be completed using the handle that
  // identified that resource.
  void InvalidateHandle(AutomationHandle handle);

  AutomationResourceProxy* GetResource(AutomationHandle handle);

  void put_channel(IPC::Channel* channel) {
    channel_ = channel;
  }

 private:
  typedef
    std::map<AutomationHandle, scoped_refptr<AutomationResourceProxy> >
        HandleToObjectMap;
  typedef std::pair<AutomationHandle, AutomationResourceProxy*> MapEntry;

  HandleToObjectMap handle_to_object_;

  Lock map_lock_;
  IPC::Channel* channel_;
  DISALLOW_EVIL_CONSTRUCTORS(AutomationHandleTracker);
};

#endif  // CHROME_TEST_AUTOMATION_AUTOMATION_HANDLE_TRACKER_H__

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