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## 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:

- `nodeIdBitLength`which determines the number of bits in a node id (which we call n).
- `idBaseBitLength`which 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 4131 2008-02-27 18:27:49Z 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.Iterator<NodeHandle>` | `alternateRoutesIterator(Id key)` More efficient implementation, but less accurate, doesn't include lower levels of rt.
`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()`
`java.lang.String` | `printSelf()`
`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

### alternateRoutesIterator

    public java.util.Iterator<NodeHandle> alternateRoutesIterator(Id key)

  More efficient implementation, but less accurate, doesn't include lower levels of rt.

  Parameters:
    `key` -
  Returns:

### 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`

### printSelf

    public java.lang.String printSelf()

### 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.

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