COM.FutureTense.Interfaces

Interface ISyncHash

public interface ISyncHash

This class presents functionality like a hashtable but with cluster sync and LRU behaviors. Note that the use of this object has performance implications. Size should be consider by cost-to-reload data vs memory usage per VM; cluster sync should be used only when a backing store is likely to change and invalidate stored results in a given VM. Operational considerations (from Netscape) suggest that data read vs write from a synchronized hash should be in a 80/20 ratio if the synchronization is across multiple machines. Non synchronized hashs do not have this suggested restriction. In theory the cost is also low if multiple VM's are on a single machine.

Version:

$Revision: 11 $

Method Summary

Modifier and Type	Method and Description
void	clear() Empty a hash - causes cluster sync as needed
Object	get(String key) Get an object from hash - performs required data validation/VM synchronization checks as needed.
String	getName() Get name
Set	keySet() Return a set of all of the keys in the current hash.
Object	put(String key, Object v) Add something to the hash; will generate appropriate cluster sync methods and LRU behavior.
Object	put(String key, Object v, Calendar cal) Deprecated. use put(String,Object,Date) insatead.
Object	put(String key, Object v, Date date) Add something to the hash; will generate appropriate cluster sync methods and LRU behavior.
Object	remove(String key) Remove an item
int	size() Return the size of the current hash

Method Detail

getName

String getName()

Get name

Returns:

Returns the name of the hash as it is managed. There is no namespace support for hash names.

put

Object put(String key,
           Object v)
    throws NullPointerException

Add something to the hash; will generate appropriate cluster sync methods and LRU behavior.

Parameters:

key - Use meaningful, reproducable key names for proper behavior. Limit length; don't use multi-K length keys. 64chars or less is a good guide; 16 chars is optimal for performance but may not be unique.

v - value

Returns:

previous object or null NOTE may toss exception(s) if the create had failed in some unexpected way

Throws:

NullPointerException - if the create had failed in some unexpected way

put

Object put(String key,
           Object v,
           Calendar cal)

Deprecated. use put(String,Object,Date) insatead.

Add something to the hash; will generate appropriate cluster sync methods and LRU behavior.

Parameters:

key - Use meaningful, reproducable key names for proper behavior. Limit length; don't use multi-K length keys. 64chars or less is a good guide; 16 chars is optimal for performance but may not be unique.

v - value

cal - Calendar object specifying the expiration time for this object in the hash. The object added will expire at the time specified by the calendar. Null is not allowed.

Returns:

previous object or null NOTE may toss exception(s) if the create had failed in some unexpected way

Since:

6.1

put

Object put(String key,
           Object v,
           Date date)

Add something to the hash; will generate appropriate cluster sync methods and LRU behavior.

Parameters:

key - Use meaningful, reproducable key names for proper behavior. Limit length; don't use multi-K length keys. 64chars or less is a good guide; 16 chars is optimal for performance but may not be unique.

v - value

date - Date object specifying the expiration time for this object in the hash. The object added will expire at the time specified by the date. Null is not allowed.

Returns:

previous object or null NOTE may toss exception(s) if the create had failed in some unexpected way

Since:

7.0

get

Object get(String key)

Get an object from hash - performs required data validation/VM synchronization checks as needed.

Parameters:

key - a key

Returns:

object or null

clear

void clear()

Empty a hash - causes cluster sync as needed

remove

Object remove(String key)

Remove an item

Parameters:

key - a key

Returns:

the object, null if not found. Causes cluster sync as needed. It is more efficient to clear() a hash then to remove all entries one by one; first is loop cost, second is cluster-sync cost which can be very high.

size

int size()

Return the size of the current hash

Returns:

int size

Since:

6.1

keySet

Set keySet()

Return a set of all of the keys in the current hash.

Returns:

Set of string keys; never null

Since:

6.1