rice.pastry.routing
Class RoutingTable

java.lang.Object
  java.util.Observable
      rice.pastry.routing.RoutingTable

All Implemented Interfaces:

NodeSetEventSource

public class RoutingTable
extends java.util.Observable
implements NodeSetEventSource

The Pastry routing table.

The size of this table is determined by two constants:

• nodeIdBitLengthwhich determines the number of bits in a node id (which we call n).
• idBaseBitLengthwhich is the base that table is stored in (which we call b).

We write out node ids as numbers in base 2 ^b . They will have length D = ceiling(log _{2 ^b} 2 ⁿ ). The table is stored from 0...(D-1) by 0...(2 ^b - 1). The table stores a set of node handles at each entry. At address [index][digit], we store the set of handles were the most significant (numerically) difference from the node id that the table routes for at the index th digit and the differing digit is digit. An index of 0 is the least significant digit.

Version:

$Id: RoutingTable.java 3801 2007-07-18 15:04:40Z jeffh $

Author:

Andrew Ladd, Peter Druschel

Field Summary

byte	idBaseBitLength The routing calculations will occur in base 2 idBaseBitLength
NodeHandle	myNodeHandle
protected PastryNode	pn
static int	TEST_FAIL_EXISTING_ARE_BETTER
static int	TEST_FAIL_NO_PREFIX_MATCH
static int	TEST_SUCCESS_AVAILABLE_SPACE
static int	TEST_SUCCESS_BETTER_PROXIMITY
static int	TEST_SUCCESS_ENTRY_WAS_DEAD
static int	TEST_SUCCESS_NO_ENTRIES

Constructor Summary

RoutingTable(NodeHandle me, int max, byte base, PastryNode pn)
Constructor.

Method Summary

void	addNodeSetListener(NodeSetListener listener)
void	addObserver(java.util.Observer o) Deprecated. use addNodeSetListener
NodeSet	alternateRoutes(Id key, int max) Determines a set of alternate hops towards a given key.
java.util.List	asList() Does not return self
byte	baseBitLength() return the bit length of the base
NodeHandle	bestAlternateRoute(Id key) Determines an alternate hop numerically closer to the key than the one we are at.
NodeHandle	bestAlternateRoute(int minLiveness, Id key) Determines an alternate hop numerically closer to the key than the one we are at.
void	deleteObserver(java.util.Observer o) Deprecated. use deleteNodeSetListener
void	destroy() Unregisters as an observer on all nodehandles.
NodeHandle	get(Id nid) Gets the node handle associated with a given id.
RouteSet	getBestEntry(Id key) Gets the set of handles that match at least one more digit of the key than the local Id.
RouteSet	getRouteSet(int index, int digit) Gets the set of handles at a particular entry in the table.
RouteSet[]	getRow(int i) Get a row from the routing table.
void	nodeSetUpdate(java.lang.Object o, NodeHandle handle, boolean added) Is called by the Observer pattern whenever a RouteSet in this table has changed.
int	numColumns() return ths number of columns in the routing table
int	numEntries()
short	numRows() return the number of rows in the routing table
int	numUniqueEntries()
boolean	put(NodeHandle handle) Puts a handle into the routing table.
NodeHandle	remove(NodeHandle nh) Removes a node id from the table.
void	removeNodeSetListener(NodeSetListener listener)
int	test(NodeHandle handle)
java.lang.String	toString() produces a String representation of the routing table, showing the number of node handles in each entry

Methods inherited from class java.util.Observable

clearChanged, countObservers, deleteObservers, hasChanged, notifyObservers, notifyObservers, setChanged

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

idBaseBitLength

public byte idBaseBitLength

The routing calculations will occur in base 2 ^{idBaseBitLength}

myNodeHandle

public NodeHandle myNodeHandle

pn

protected PastryNode pn

TEST_FAIL_NO_PREFIX_MATCH

public static final int TEST_FAIL_NO_PREFIX_MATCH

See Also:

Constant Field Values

TEST_FAIL_EXISTING_ARE_BETTER

public static final int TEST_FAIL_EXISTING_ARE_BETTER

See Also:

Constant Field Values

TEST_SUCCESS_BETTER_PROXIMITY

public static final int TEST_SUCCESS_BETTER_PROXIMITY

See Also:

Constant Field Values

TEST_SUCCESS_ENTRY_WAS_DEAD

public static final int TEST_SUCCESS_ENTRY_WAS_DEAD

See Also:

Constant Field Values

TEST_SUCCESS_AVAILABLE_SPACE

public static final int TEST_SUCCESS_AVAILABLE_SPACE

See Also:

Constant Field Values

TEST_SUCCESS_NO_ENTRIES

public static final int TEST_SUCCESS_NO_ENTRIES

See Also:

Constant Field Values

Constructor Detail

RoutingTable

public RoutingTable(NodeHandle me,
                    int max,
                    byte base,
                    PastryNode pn)

Constructor.

Parameters:

me - the node id for this routing table.

max - the maximum number of entries at each table slot.

Method Detail

numColumns

public int numColumns()

return ths number of columns in the routing table

Returns:

number of columns

numRows

public short numRows()

return the number of rows in the routing table

Returns:

number of rows

baseBitLength

public byte baseBitLength()

return the bit length of the base

Returns:

baseBitLength

bestAlternateRoute

public NodeHandle bestAlternateRoute(Id key)

Determines an alternate hop numerically closer to the key than the one we are at. This assumes that bestEntry did not produce a live nodeHandle that matches the next digit of the key.

Parameters:

key - the key

Returns:

a nodeHandle of a numerically closer node, relative to the key

bestAlternateRoute

public NodeHandle bestAlternateRoute(int minLiveness,
                                     Id key)

Determines an alternate hop numerically closer to the key than the one we are at. This assumes that bestEntry did not produce a live nodeHandle that matches the next digit of the key.

Parameters:

key - the key

Returns:

a nodeHandle of a numerically closer node, relative to the key

alternateRoutes

public NodeSet alternateRoutes(Id key,
                               int max)

Determines a set of alternate hops towards a given key.

Parameters:

key - the key

max - the maximal number of alternate hops requested

Returns:

a set of nodehandles, or null if no alternate hops exist

getRouteSet

public RouteSet getRouteSet(int index,
                            int digit)

Gets the set of handles at a particular entry in the table.

Parameters:

index - the index of the digit in base 2 ^{idBaseBitLength} .0 is the least significant.

digit - ranges from 0... 2 ^{idBaseBitLength - 1} . Selects which digit to use.

Returns:

a read-only set of possible handles located at that position in the routing table, or null if none are known

getBestEntry

public RouteSet getBestEntry(Id key)

Gets the set of handles that match at least one more digit of the key than the local Id.

Parameters:

key - the key

Returns:

a read-only set of possible handles, or null if none are known

put

public boolean put(NodeHandle handle)

Puts a handle into the routing table.

Parameters:

handle - the handle to put.

test

public int test(NodeHandle handle)

get

public NodeHandle get(Id nid)

Gets the node handle associated with a given id.

Parameters:

nid - a node id

Returns:

the handle associated with that id, or null if none is known.

getRow

public RouteSet[] getRow(int i)

Get a row from the routing table.

Parameters:

i - which row

Returns:

an array which is the ith row.

remove

public NodeHandle remove(NodeHandle nh)

Removes a node id from the table.

Parameters:

nid - the node id to remove.

Returns:

the handle that was removed, or null if it did not exist.

nodeSetUpdate

public void nodeSetUpdate(java.lang.Object o,
                          NodeHandle handle,
                          boolean added)

Is called by the Observer pattern whenever a RouteSet in this table has changed.

Parameters:

o - the RouteSet

arg - the event

toString

public java.lang.String toString()

produces a String representation of the routing table, showing the number of node handles in each entry

Overrides:

toString in class java.lang.Object

numEntries

public int numEntries()

numUniqueEntries

public int numUniqueEntries()

addObserver

public void addObserver(java.util.Observer o)

Deprecated. use addNodeSetListener

Generates too many objects to use this interface

Overrides:

addObserver in class java.util.Observable

deleteObserver

public void deleteObserver(java.util.Observer o)

Deprecated. use deleteNodeSetListener

Generates too many objects to use this interface

Overrides:

deleteObserver in class java.util.Observable

addNodeSetListener

public void addNodeSetListener(NodeSetListener listener)

Specified by:

addNodeSetListener in interface NodeSetEventSource

removeNodeSetListener

public void removeNodeSetListener(NodeSetListener listener)

Specified by:

removeNodeSetListener in interface NodeSetEventSource

asList

public java.util.List asList()

Does not return self

Returns:

list of NodeHandle

destroy

public void destroy()

Unregisters as an observer on all nodehandles.