source: source/services/dht/Dht.h@ 10673

/*

 * Dht.h

 *

 *  Created on: 20.06.2012

 *      Author: mario

 */



#ifndef DHT_H_

#define DHT_H_



#include "ariba/ariba.h"

#include "ariba/utility/system/SystemQueue.h"

#include "ariba/utility/logging/Logging.h"

#include "messages/DhtMessage.h"

#include "DhtAnswerInterface.h"

#include <boost/date_time/posix_time/posix_time.hpp>

#include <boost/noncopyable.hpp>

#include <set>



namespace ariba_service {

namespace dht {



using ariba::utility::SystemQueue;

using ariba::utility::SystemEvent;

using ariba::utility::SystemEventType;

using ariba::utility::SystemEventListener;



#define MEET_REPUBLISH_INTERVAL 10

#define MEET_DHT_TTL 30

#define CLEANUP_INTERVAL (5 * 60)



class Dht :

        public ariba::CommunicationListener,

        public ariba::utility::SystemEventListener,

        public boost::noncopyable

{

use_logging_h(Dht)

public:

    Dht(ariba::ServiceID serviceID, ariba::Node* node);

    virtual ~Dht();

    

    /**

     * Put the value into the DHT under the specified key

     * 

     * @param key

     *     Key to put the value under

     * @param value

     *     The value which is put

     * @param ttl

     *     The lifetime of the entry in seconds. The value will be removed

     *     automatically when it expires

     */

    void put(

                const std::string& key,

                const std::string& value,

                uint16_t ttl);

    

    /**

     * Get the values specified by the key

     * 

     * @param key

     *      Key of the values which should be fetched

     */

    void get(const std::string& key);

    

    /**

     * Put and get in one single operation

     * 

     * @param key

     *     The key the value will be put under and retrieved from

     * @param value

     *     The value is first put then all values for that key, including the

     *     one just inserted will be sent back

     * @param ttl

     *     The lifetime of the entry in seconds. The value will be removed

     *     automatically when it expires

     */

    void atomic_put_and_get(

                const std::string& key,

                const std::string& value,

                uint16_t ttl);

    

    /**

     * Periodically put and get the value

     * 

     * @param key

     *     The key the value will be put under and retrieved from

     * @param value

     *     The value that will be periodically put into the DHT. The value is

     *     first put then all values for that key, including the one just

     *     inserted will be sent back

     * @param ttl

     *     How long should we try to put the value periodically (measured in

     *     seconds). 0 means putting the value until stop_meet() is called

     */

    void meet(

                const std::string& key,

                const std::string& value,

                uint16_t ttl);

    

    /**

     * Stop periodically pushing the value

     */

    void stop_meet(const std::string& key, const std::string& value);

    

    /**

     * Remove the value under the specified key

     */

    void remove(const std::string& key, const std::string& value);

    

    /**

     * Register a listener which is called when an answer is received

     */

    bool add_listener(DhtAnswerInterface* new_listener);



    /**

     * Unregister a listener

     * 

     * @returns true if the handler was successfully unregistered, false if the

     *     listener was not registered

     */

    bool remove_listener(DhtAnswerInterface* new_listener);

    

protected:

    /*** CommunicationListener interface ***/

    

    /**

     * Called when a message is incoming

     * @param msg The data message that is received

     * @param remote The remote node that sent the message

     * @param lnk The link id of the link where the message is received

     */

    virtual void onMessage(const ariba::DataMessage& msg, const ariba::NodeID& source,

            const ariba::LinkID& lnk = ariba::LinkID::UNSPECIFIED);

    

    

    virtual void handle_dht_message(const DhtMessage& message, const NodeID& source);



    /*** SystemEventListener interface ***/

    virtual void handleSystemEvent( const SystemEvent& event );





private:

    class ValueEntry {

        public:

                ValueEntry(const std::string& value, uint16_t ttl = 0);

                

                void refresh();

                

                const std::string& get_value() const;

                

                uint16_t get_age() const;

                

                uint16_t get_ttl() const;

                void set_ttl(uint16_t ttl);

                bool is_ttl_elapsed() const;

                uint16_t get_remaining_ttl() const;

                

                bool operator<(const ValueEntry& rhs) const;

                

        private:

                uint16_t ttl;

                boost::posix_time::ptime last_update;

                std::string value;

        };

    

    struct Key_Value

    {

        string key;

        string value;

    };

    



private:

    void answer_dht_request(const std::string& key, const NodeID& source);

    void send_meet_message(const std::string& key, const std::string& value);

    void meet_update_event(const std::string& key, const std::string& value);

    

    // just for debug purpose

    void print_dht();

    

    

    ariba::ServiceID serviceID;

    ariba::Node* node;

    

    typedef std::map< std::string, std::vector<ValueEntry> > DhtTableType;

    DhtTableType table;

    DhtTableType meet_store;

    

    void insert_into_table(DhtTableType& table,

                const std::string& key,

                const vector<std::string>& values,

                uint16_t ttl);

    void remove_from_table(DhtTableType& table,

                const std::string& key,

                const vector<std::string>& values);

    void cleanup_table(DhtTableType& table);

    void cleanup_entries(DhtTableType::mapped_type& entries);

    

    void schedule_cleanup_event(bool reschedule = false);

    bool cleanup_running;

    

    // AnswerListener

    DhtAnswerInterface* listener;

};





}} /* namespace ariba_service::dht */





#endif /* DHT_H_ */