/******************************************************************************
 *                       ____    _    _____                                   *
 *                      / ___|  / \  |  ___|    C++                           *
 *                     | |     / _ \ | |_       Actor                         *
 *                     | |___ / ___ \|  _|      Framework                     *
 *                      \____/_/   \_|_|                                      *
 *                                                                            *
 * Copyright (C) 2011 - 2015                                                  *
 * Dominik Charousset <dominik.charousset (at) haw-hamburg.de>                *
 *                                                                            *
 * Distributed under the terms and conditions of the BSD 3-Clause License or  *
 * (at your option) under the terms and conditions of the Boost Software      *
 * License 1.0. See accompanying files LICENSE and LICENSE_ALTERNATIVE.       *
 *                                                                            *
 * If you did not receive a copy of the license files, see                    *
 * http://opensource.org/licenses/BSD-3-Clause and                            *
 * http://www.boost.org/LICENSE_1_0.txt.                                      *
 ******************************************************************************/

#ifndef CAF_ACTOR_PROXY_HPP
#define CAF_ACTOR_PROXY_HPP

#include <atomic>
#include <cstdint>

#include "caf/abstract_actor.hpp"
#include "caf/monitorable_actor.hpp"

#include "caf/detail/shared_spinlock.hpp"

namespace caf {

class actor_proxy;

/// A smart pointer to an {@link actor_proxy} instance.
/// @relates actor_proxy
using actor_proxy_ptr = intrusive_ptr<actor_proxy>;

/// Represents an actor running on a remote machine,
/// or different hardware, or in a separate process.
class actor_proxy : public monitorable_actor {
public:
  /// An anchor points to a proxy instance without sharing
  /// ownership to it, i.e., models a weak ptr.
  class anchor : public ref_counted {
  public:
    friend class actor_proxy;

    anchor(actor_proxy* instance = nullptr);

    ~anchor();

    /// Queries whether the proxy was already deleted.
    bool expired() const;

    /// Gets a pointer to the proxy or `nullptr`
    ///    if the instance is {@link expired()}.
    actor_proxy_ptr get();

  private:
    /*
     * Tries to expire this anchor. Fails if reference
     *    count of the proxy is nonzero.
     */
    bool try_expire() noexcept;
    std::atomic<actor_proxy*> ptr_;
    detail::shared_spinlock lock_;
  };

  using anchor_ptr = intrusive_ptr<anchor>;

  ~actor_proxy();

  /// Establishes a local link state that's not synchronized back
  ///    to the remote instance.
  virtual void local_link_to(const actor_addr& other) = 0;

  /// Removes a local link state.
  virtual void local_unlink_from(const actor_addr& other) = 0;

  /// Invokes cleanup code.
  virtual void kill_proxy(execution_unit* ctx, exit_reason reason) = 0;

  void request_deletion(bool decremented_ref_count) noexcept override;

  inline anchor_ptr get_anchor() const {
    return anchor_;
  }

protected:
  actor_proxy(actor_id aid, node_id nid);

  anchor_ptr anchor_;
};

} // namespace caf

#endif // CAF_ACTOR_PROXY_HPP
