source: source/ariba/overlay/modules/chord/Chord.h@ 3690

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// Copyright (c) 2008-2009, Institute of Telematics, UniversitÀt Karlsruhe (TH)
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// [License]

#ifndef CHORD_H_
#define CHORD_H_

#include "ariba/utility/system/Timer.h"
#include "ariba/utility/logging/Logging.h"
#include "ariba/communication/EndpointDescriptor.h"
#include "../OverlayInterface.h"
#include <vector>

class chord_routing_table;

namespace ariba {
namespace overlay {

using ariba::communication::EndpointDescriptor;
using ariba::utility::Timer;

using namespace std;

/**
 * This class implements a structured overlay inspired by chord.
 * It differs to the original form of chord in the following manner:
 *
 * (1) The graph is bidirectional
 * (2) Stabilization is done in a reactive manner
 *
 * It therefore can be considered as a kind of Chorded-Kademlia :)
 *
 * The resulting overlay graph has a diameter of O(log N).
 *
 * @author Sebastian Mies <mies@tm.uka.de>
 */
class Chord : public OverlayInterface, protected Timer {
        use_logging_h( Chord );
private:
        chord_routing_table* table;
        int orphan_removal_counter;
        int stabilize_counter;
        int stabilize_finger;
        LinkID bootstrapLink;

        // helper: sets up a link using the "base overlay"
        LinkID setup( const EndpointDescriptor& endp );

        // helper: sends a message using the "base overlay"
        seqnum_t send( Message* msg, const LinkID& link );

        // stabilization: sends a discovery message to the specified neighborhood
        void send_discovery_to( const NodeID& destination, int ttl = 4 );

public:
        Chord(BaseOverlay& _baseoverlay, const NodeID& _nodeid,
                        OverlayStructureEvents* _eventsReceiver);
        virtual ~Chord();

        /// @see OverlayInterface.h
        virtual void createOverlay();

        /// @see OverlayInterface.h
        virtual void deleteOverlay();

        /// @see OverlayInterface.h
        virtual void joinOverlay(
                const EndpointDescriptor& boot = EndpointDescriptor::UNSPECIFIED
        );

        /// @see OverlayInterface.h
        virtual void leaveOverlay();

        /// @see OverlayInterface.h
        virtual const EndpointDescriptor& resolveNode( const NodeID& node );

        /// @see OverlayInterface.h
        virtual void routeMessage( const NodeID& destnode, Message* msg );

        /// @see OverlayInterface.h
        virtual NodeList getKnownNodes() const;

        /// @see CommunicationListener.h or @see OverlayInterface.h
        virtual void onLinkUp(const LinkID& lnk, const NodeID& remote);

        /// @see CommunicationListener.h or @see OverlayInterface.h
        virtual void onLinkDown(const LinkID& lnk, const NodeID& remote);

        /// @see CommunicationListener.h or @see OverlayInterface.h
        virtual void onMessage(const DataMessage& msg, const NodeID& remote,
                        const LinkID& lnk = LinkID::UNSPECIFIED);

        /// @see Timer.h
        virtual void eventFunction();
};

}}

#endif /* CHORD_H_ */