com.bigdata.bop

Interface IQueryAttributes

All Known Implementing Classes:

DefaultQueryAttributes

public interface IQueryAttributes

An interface providing access to named attribute values which may be shared across operators or across multiple invocations of the same operator. The bindings are scoped to the owning IQueryContext.

The key MUST include enough information to provide for the scope of the attribute within the query and is typically the bop identifier plus an attribute name. Bindings DO NOT cross a service partition so it is not necessary to add the shardId or service UUID to the key.

Version:

$Id$

Author:

Bryan Thompson

Method Summary

Methods

Modifier and Type	Method and Description
Object	get(Object key) Return the attribute value under the key.
Object	put(Object key, Object val) Bind an attribute under the key.
Object	putIfAbsent(Object key, Object val) Atomically bind an attribute value under the key iff the key is not already bound.
Object	remove(Object key) Remove the attribute under the key.
boolean	remove(Object key, Object value) Atomically remove the attribute under the key iff it has the given value.

Method Detail

get

Object get(Object key)

Return the attribute value under the key.

Parameters:

key - The key.

Returns:

The attribute value under that key -or- null if there is no bound attribute for that key.

put

Object put(Object key,
         Object val)

Bind an attribute under the key.

Parameters:

key - The key.

val - The new value (may not be null).

Returns:

The old value.

See Also:

get(Object)

putIfAbsent

Object putIfAbsent(Object key,
                 Object val)

Atomically bind an attribute value under the key iff the key is not already bound.

Parameters:

key - The key.

val - The new value (may not be null).

Returns:

The old value.

remove

Object remove(Object key)

Remove the attribute under the key.

Parameters:

key - The key.

Returns:

The old value.

remove

boolean remove(Object key,
             Object value)

Atomically remove the attribute under the key iff it has the given value.

Parameters:

key - The key.

value - The expected value for that key.

Returns:

true iff the entry for that key was removed.