com.limegroup.gnutella.altlocs
Class AbstractAlternateLocation

java.lang.Object
  com.limegroup.gnutella.altlocs.AbstractAlternateLocation

All Implemented Interfaces:

AlternateLocation, HTTPHeaderValue, Comparable<AlternateLocation>

Direct Known Subclasses:

DirectAltLoc, PushAltLoc

public abstract class AbstractAlternateLocation
extends Object
implements AlternateLocation

Abstract super class that encompasses common functionality shared by most implementations of AlternateLocation.

Field Summary

protected int	_count maintins a count of how many times this alternate location has been seen.
protected int	hashCode Cached hash code that is lazily initialized.
protected URN	SHA1_URN Constant for the sha1 urn for this AlternateLocation -- can be null.

Fields inherited from interface com.limegroup.gnutella.altlocs.AlternateLocation

ALT_VENDOR, MESH_LEGACY, MESH_PING, MESH_RESPONSE

Constructor Summary

protected

AbstractAlternateLocation(URN sha1)

Method Summary

boolean	canBeSent(int meshType)
boolean	canBeSentAny()
int	compareTo(AlternateLocation other) The idea is that this is smaller than any AlternateLocation who has a greater value of _count.
abstract AlternateLocation	createClone() could return null
abstract RemoteFileDesc	createRemoteFileDesc(long size, RemoteFileDescFactory remoteFileDescFactory) Creates a new RemoteFileDesc from this AlternateLocation
boolean	equals(Object obj) Overrides the equals method to accurately compare AlternateLocation instances.
protected abstract String	generateHTTPString()
int	getCount() Accessor to find if this has been demoted
URN	getSHA1Urn() Accessor for the SHA1 urn for this AlternateLocation.
int	hashCode() Overrides the hashCode method of Object to meet the contract of hashCode.
String	httpStringValue() Returns a string representation of the HTTP header value for this class.
void	increment() increment the count.
abstract boolean	isDemoted() package access, accessor to the value of _demoted
abstract boolean	isMe()
void	send(long now, int meshType)

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Field Detail

SHA1_URN

protected final URN SHA1_URN

Constant for the sha1 urn for this AlternateLocation -- can be null.

hashCode

protected volatile int hashCode

Cached hash code that is lazily initialized.

_count

protected volatile int _count

maintins a count of how many times this alternate location has been seen. A value of 0 means this alternate location was failed one more time that it has succeeded. Newly created AlternateLocations start out wit a value of 1.

Constructor Detail

AbstractAlternateLocation

protected AbstractAlternateLocation(URN sha1)

Method Detail

getSHA1Urn

public URN getSHA1Urn()

Description copied from interface: AlternateLocation

Accessor for the SHA1 urn for this AlternateLocation.

Specified by:

getSHA1Urn in interface AlternateLocation

Returns:

the SHA1 urn for the this AlternateLocation

getCount

public int getCount()

Description copied from interface: AlternateLocation

Accessor to find if this has been demoted

Specified by:

getCount in interface AlternateLocation

isDemoted

public abstract boolean isDemoted()

Description copied from interface: AlternateLocation

package access, accessor to the value of _demoted

Specified by:

isDemoted in interface AlternateLocation

httpStringValue

public String httpStringValue()

Description copied from interface: HTTPHeaderValue

Returns a string representation of the HTTP header value for this class.

Specified by:

httpStringValue in interface HTTPHeaderValue

Returns:

a string representation of the HTTP header value for this class

createRemoteFileDesc

public abstract RemoteFileDesc createRemoteFileDesc(long size,
                                                    RemoteFileDescFactory remoteFileDescFactory)

Description copied from interface: AlternateLocation

Creates a new RemoteFileDesc from this AlternateLocation

Specified by:

createRemoteFileDesc in interface AlternateLocation

Parameters:

size - the size of the file for the new RemoteFileDesc -- this is necessary to make sure the download bucketing works correctly

Returns:

new RemoteFileDesc based off of this, or null if the RemoteFileDesc could not be created

isMe

public abstract boolean isMe()

Specified by:

isMe in interface AlternateLocation

Returns:

whether this is an alternate location pointing to myself.

increment

public void increment()

Description copied from interface: AlternateLocation

increment the count.

Specified by:

increment in interface AlternateLocation

See Also:

demote

createClone

public abstract AlternateLocation createClone()

Description copied from interface: AlternateLocation

could return null

Specified by:

createClone in interface AlternateLocation

send

public void send(long now,
                 int meshType)

Specified by:

send in interface AlternateLocation

canBeSent

public boolean canBeSent(int meshType)

Specified by:

canBeSent in interface AlternateLocation

canBeSentAny

public boolean canBeSentAny()

Specified by:

canBeSentAny in interface AlternateLocation

equals

public boolean equals(Object obj)

Overrides the equals method to accurately compare AlternateLocation instances. AlternateLocations are equal if their URLs are equal.

Overrides:

equals in class Object

Parameters:

obj - the Object instance to compare to

Returns:

true if the URL of this AlternateLocation is equal to the URL of the AlternateLocation location argument, and otherwise returns false

compareTo

public int compareTo(AlternateLocation other)

The idea is that this is smaller than any AlternateLocation who has a greater value of _count. There is one exception to this rule -- a demoted AlternateLocation has a higher value irrespective of count.

This is because we want to have a sorted set of AlternateLocation where any demoted AlternateLocation is put at the end of the list because it probably does not work.

Further we want to get AlternateLocations with smaller counts to be propogated more, since this will serve to get better load balancing of uploader.

Specified by:

compareTo in interface Comparable<AlternateLocation>

generateHTTPString

protected abstract String generateHTTPString()

hashCode

public int hashCode()

Overrides the hashCode method of Object to meet the contract of hashCode. Since we override equals, it is necessary to also override hashcode to ensure that two "equal" alternate locations return the same hashCode, less we unleash unknown havoc on the hash-based collections.

Overrides:

hashCode in class Object

Returns:

a hash code value for this object