Line data    Source code

       1             : /*
       2             :  * Copyright (c) 2017 Juniper Networks, Inc. All rights reserved.
       3             :  */
       4             : 
       5             : #ifndef event_notifier_h
       6             : #define event_notifier_h
       7             : 
       8             : #include <atomic>
       9             : 
      10             : #include <base/util.h>
      11             : #include <base/queue_task.h>
      12             : #include <boost/shared_ptr.hpp>
      13             : 
      14             : /*
      15             :  * Event Notifier
      16             :  *
      17             :  * This routine is a kind of pub-sub mechanism for non db notifications.
      18             :  *
      19             :  * Subscriber:
      20             :  * All subscribers can register with a key. Key identifies the type of
      21             :  * notification. Subscriber also provides the task context in which it expects
      22             :  * the notification. On registeration it is given a handle which can be used to
      23             :  * deregister. Same subscriber can also register multiple callbacks. Each
      24             :  * registeration is segregated by handle returned agter registeration.
      25             :  *
      26             :  * Publisher:
      27             :  * Publisher uses key like subscriber for kind of notification. Calls Notify and
      28             :  * that call in turn call all subscribers. If nobody has subscribed nothing has
      29             :  * to be done.
      30             :  *
      31             :  * Implementatin details:
      32             :  * There is a vector of handles maintained on per key basis. To achieve task
      33             :  * context based notification on per susbcriber basis, task trigger is used.
      34             :  * On every registeration a tasktrigger object is created with callback and task
      35             :  * id. This object along with key is bundled in handle which is returned to
      36             :  * subscriber.
      37             :  *
      38             :  */
      39             : class EventNotifier;
      40             : 
      41             : struct EventNotifyKey {
      42             : public:
      43             :     enum Type {
      44             :         END_OF_RIB,
      45             :         GENERIC
      46             :     };
      47             :     EventNotifyKey(Type type);
      48             :     virtual ~EventNotifyKey();
      49             : 
      50             :     virtual bool IsLess(const EventNotifyKey &rhs) const;
      51           0 :     Type type() const {return type_;}
      52             : 
      53             : private:
      54             :     std::atomic<int> ref_count_;
      55             :     Type type_;
      56             : };
      57             : 
      58             : struct EventNotifyHandle {
      59             :     typedef boost::shared_ptr<EventNotifyKey> KeyPtr;
      60             :     typedef boost::shared_ptr<EventNotifyHandle> Ptr;
      61             :     typedef boost::function<bool(void)> Callback;
      62             : 
      63             :     EventNotifyHandle(KeyPtr key, Callback cb);
      64             :     virtual ~EventNotifyHandle();
      65           0 :     KeyPtr key() const {return key_;}
      66           0 :     void Notify() const {cb_();}
      67             : 
      68             : private:
      69             :     KeyPtr key_;
      70             :     Callback cb_;
      71             : };
      72             : 
      73             : class EventNotifier {
      74             : public:
      75             :     //Callback
      76             :     typedef boost::function<bool(void)> Callback;
      77             :     //Key Ptr
      78             :     typedef boost::shared_ptr<EventNotifyKey> KeyPtr;
      79             :     typedef SmartPointerComparator<EventNotifyKey, boost::shared_ptr> Comparator;
      80             :     //subscriber callback list, vector of handles
      81             :     typedef std::vector<EventNotifyHandle::Ptr> SubscribersList;
      82             :     typedef SubscribersList::iterator SubscribersListIter;
      83             :     //key to call back list map
      84             :     typedef std::map<KeyPtr, SubscribersList, Comparator> NotifyMap;
      85             :     typedef NotifyMap::iterator NotifyMapIter;
      86             : 
      87             :     EventNotifier(Agent *agent);
      88             :     virtual ~EventNotifier();
      89             : 
      90             :     //Publisher routines
      91             :     void Notify(EventNotifyKey *key);
      92             : 
      93             :     //Subscriber routines
      94             :     EventNotifyHandle::Ptr RegisterSubscriber(EventNotifyKey *key,
      95             :                                               Callback callback);
      96             :     void DeregisterSubscriber(EventNotifyHandle::Ptr ptr);
      97             : 
      98             : private:
      99             :     struct WorkQueueMessage {
     100             :     public:
     101             :         typedef boost::shared_ptr<WorkQueueMessage> Ptr;
     102             :         enum Type {
     103             :             PUBLISHER,
     104             :             REGISTER_SUBSCRIBER,
     105             :             DEREGISTER_SUBSCRIBER
     106             :         };
     107             :         WorkQueueMessage(Type type, EventNotifyHandle::Ptr handle);
     108             :         Type type_;
     109             :         EventNotifyHandle::Ptr handle_ptr_;
     110             :     };
     111             :     //Work queue enqueue/dequeue
     112             :     bool Enqueue(WorkQueueMessage::Ptr data);
     113             :     bool Process(WorkQueueMessage::Ptr data);
     114             : 
     115             :     void NotifyInternal(KeyPtr key);
     116             :     void RegisterSubscriberInternal(EventNotifyHandle::Ptr ptr);
     117             :     void DeRegisterSubscriberInternal(EventNotifyHandle::Ptr ptr);
     118             : 
     119             :     NotifyMap map_;
     120             :     WorkQueue<WorkQueueMessage::Ptr> work_queue_;
     121             :     Agent *agent_;
     122             :     DISALLOW_COPY_AND_ASSIGN(EventNotifier);
     123             : };
     124             : 
     125             : #endif //event_notifier_h