// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- 
// vim: ts=8 sw=2 smarttab
/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software 
 * Foundation.  See file COPYING.
 * 
 */
#ifndef CEPH_WATCH_H
#define CEPH_WATCH_H

#include <boost/intrusive_ptr.hpp>
#include <tr1/memory>
#include <set>

#include "msg/Messenger.h"
#include "include/Context.h"
#include "common/Mutex.h"

enum WatcherState {
  WATCHER_PENDING,
  WATCHER_NOTIFIED,
};

class OSDService;
class ReplicatedPG;
void intrusive_ptr_add_ref(ReplicatedPG *pg);
void intrusive_ptr_release(ReplicatedPG *pg);
class ObjectContext;
class MWatchNotify;

class Watch;
typedef std::tr1::shared_ptr<Watch> WatchRef;
typedef std::tr1::weak_ptr<Watch> WWatchRef;

class Notify;
typedef std::tr1::shared_ptr<Notify> NotifyRef;
typedef std::tr1::weak_ptr<Notify> WNotifyRef;

class CancelableContext;

/**
 * Notify tracks the progress of a particular notify
 *
 * References are held by Watch and the timeout callback.
 */
class NotifyTimeoutCB;
class Notify {
  friend class NotifyTimeoutCB;
  friend class Watch;
  WNotifyRef self;
  ConnectionRef client;
  unsigned in_progress_watchers;
  bool complete;
  bool discarded;
  set<WatchRef> watchers;

  bufferlist payload;
  uint32_t timeout;
  uint64_t cookie;
  uint64_t notify_id;
  uint64_t version;

  OSDService *osd;
  CancelableContext *cb;
  Mutex lock;


  /// true if this notify is being discarded
  bool is_discarded() {
    return discarded || complete;
  }

  /// Sends notify completion if in_progress_watchers == 0
  void maybe_complete_notify();

  /// Called on Notify timeout
  void do_timeout();

  Notify(
    ConnectionRef client,
    unsigned num_watchers,
    bufferlist &payload,
    uint32_t timeout,
    uint64_t cookie,
    uint64_t notify_id,
    uint64_t version,
    OSDService *osd);

  /// registers a timeout callback with the watch_timer
  void register_cb();

  /// removes the timeout callback, called on completion or cancellation
  void unregister_cb();
public:
  string gen_dbg_prefix() {
    stringstream ss;
    ss << "Notify(" << make_pair(cookie, notify_id) << " "
       << " in_progress_watchers=" << in_progress_watchers
       << ") ";
    return ss.str();
  }
  void set_self(NotifyRef _self) {
    self = _self;
  }
  static NotifyRef makeNotifyRef(
    ConnectionRef client,
    unsigned num_watchers,
    bufferlist &payload,
    uint32_t timeout,
    uint64_t cookie,
    uint64_t notify_id,
    uint64_t version,
    OSDService *osd);

  /// Call after creation to initialize
  void init();

  /// Called once per watcher prior to init()
  void start_watcher(
    WatchRef watcher ///< [in] watcher to complete
    );

  /// Called once per NotifyAck
  void complete_watcher(
    WatchRef watcher ///< [in] watcher to complete
    );

  /// Called when the notify is canceled due to a new peering interval
  void discard();
};

/**
 * Watch is a mapping between a Connection and an ObjectContext
 *
 * References are held by ObjectContext and the timeout callback
 */
class HandleWatchTimeout;
class HandleDelayedWatchTimeout;
class Watch {
  WWatchRef self;
  friend class HandleWatchTimeout;
  friend class HandleDelayedWatchTimeout;
  ConnectionRef conn;
  CancelableContext *cb;

  OSDService *osd;
  boost::intrusive_ptr<ReplicatedPG> pg;
  ObjectContext *obc;

  std::map<uint64_t, NotifyRef> in_progress_notifies;

  uint32_t timeout;
  uint64_t cookie;
  entity_name_t entity;
  bool discarded;

  Watch(
    ReplicatedPG *pg, OSDService *osd,
    ObjectContext *obc, uint32_t timeout,
    uint64_t cookie, entity_name_t entity);

  /// Registers the timeout callback with watch_timer
  void register_cb();

  /// Unregisters the timeout callback
  void unregister_cb();

  /// send a Notify message when connected for notif
  void send_notify(NotifyRef notif);

  /// Cleans up state on discard or remove (including Connection state, obc)
  void discard_state();
public:
  /// NOTE: must be called with pg lock held
  ~Watch();

  string gen_dbg_prefix();
  static WatchRef makeWatchRef(
    ReplicatedPG *pg, OSDService *osd,
    ObjectContext *obc, uint32_t timeout, uint64_t cookie, entity_name_t entity);
  void set_self(WatchRef _self) {
    self = _self;
  }

  /// Does not grant a ref count!
  boost::intrusive_ptr<ReplicatedPG> get_pg() { return pg; }

  /// Grants a ref count!
  ObjectContext *get_obc();
  uint64_t get_cookie() const { return cookie; }
  entity_name_t get_entity() const { return entity; }

  /// Generates context for use if watch timeout is delayed by scrub or recovery
  Context *get_delayed_cb();

  /// True if currently connected
  bool connected();

  /// Transitions Watch to connected, unregister_cb, resends pending Notifies
  void connect(
    ConnectionRef con ///< [in] Reference to new connection
    );

  /// Transitions watch to disconnected, register_cb
  void disconnect();

  /// Called if Watch state is discarded due to new peering interval
  void discard();

  /// True if removed or discarded
  bool is_discarded();

  /// Called on unwatch
  void remove();

  /// Adds notif as in-progress notify
  void start_notify(
    NotifyRef notif ///< [in] Reference to new in-progress notify
    );

  /// Removes timed out notify
  void cancel_notify(
    NotifyRef notif ///< [in] notify which timed out
    );

  /// Call when notify_ack received on notify_id
  void notify_ack(
    uint64_t notify_id ///< [in] id of acked notify
    );
};

/**
 * Holds weak refs to Watch structures corresponding to a connection
 * Lives in the OSD::Session object of an OSD connection
 */
class WatchConState {
  Mutex lock;
  std::set<WatchRef> watches;
public:
  WatchConState() : lock("WatchConState") {}

  /// Add a watch
  void addWatch(
    WatchRef watch ///< [in] Ref to new watch object
    );

  /// Remove a watch
  void removeWatch(
    WatchRef watch ///< [in] Ref to watch object to remove
    );

  /// Called on session reset, disconnects watchers
  void reset();
};

#endif