source: source/ariba/overlay/modules/chord/Chord.h@ 12755

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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>
#include <stdexcept>

class chord_routing_table;

namespace ariba {
namespace overlay {

class OverlayMsg;

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;
        vector<LinkID> bootstrapLinks;
        vector<NodeID> pending;
        vector<NodeID> discovery;
        int discovery_count;

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

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

        // helper: sends a message to a node using the "base overlay"
        void send_node( OverlayMsg* message, const NodeID& remote );
                
        // stabilization: sends a discovery message to the specified neighborhood
        void send_discovery_to( const NodeID& destination, int ttl = 3 );

        void discover_neighbors( const LinkID& lnk );

        void showLinks();

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

        /// @see OverlayInterface.h
        virtual const LinkID& getNextLinkId( const NodeID& id ) const;
        
    /// @see OverlayInterface.h
    /// NOTE: This implementation excepts num == 2
    virtual std::vector<const LinkID*> getSortedLinkIdsTowardsNode(
        const NodeID& id, int num = 0 ) const;

        /// @see OverlayInterface.h
        virtual const NodeID& getNextNodeId( const NodeID& id ) const;

        /// @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 bool isClosestNodeTo( const NodeID& node );

        /// @see OverlayInterface.h
        virtual NodeList getKnownNodes(bool deep = true) 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(OverlayMsg* msg,
                reboost::shared_buffer_t sub_msg,
                const NodeID& remote,
                        const LinkID& lnk = LinkID::UNSPECIFIED);

        /// @see OverlayInterface.h
        virtual std::string debugInformation() const;

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

};

}}

#endif /* CHORD_H_ */