LazyTemporalAttributeStorage (JTemporal)

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net.sf.jtemporal.spi
Class LazyTemporalAttributeStorage<V>

java.lang.Object
  net.sf.jtemporal.spi.LazyTemporalAttributeStorage<V>


Type Parameters:: V - the type of the value

All Implemented Interfaces:: TemporalAttributeStorage

public class LazyTemporalAttributeStorage<V>
extends java.lang.Object
implements TemporalAttributeStorage
extends java.lang.Object
implements TemporalAttributeStorage

This storage is based on a cache whose size grows lazily, until all the underlying data is in the cache. This caching strategy is appropriate for applications handling primarily recent data, which is the case of most applications

It loads lazily the data between the positive infinity and the requested instant. If subsequently you ask an instant that precedes the previous request, it loads then the gap between both requested instants. This continues until the whole history is in cache.
Unlike usual caching APIs, these methods intentionally return void, in order to give you full freedom in implementing prefetching strategies, where on a call you decide to load more data than requested, possibly in other instances of LazyTemporalAttributeStorage.
Warning: the methods with no instant or period as a parameter usually cause the entire underlying data to be loaded. For example, isEmpty() will load all the underlying data.

Version:: $Id: LazyTemporalAttributeStorage.java,v 1.17 2007/09/14 20:03:11 tabeck Exp $

Nested Class Summary
`static interface`	`LazyTemporalAttributeStorage.ChangeHandler<V>` Applies the changes on the underlying data source.
`static interface`	`LazyTemporalAttributeStorage.MissingRangeHandler<V>` Loads the data from the real physical storage into the the LazyTemporalAttributeStorage cache, when additional data is requested.

Constructor Summary
`LazyTemporalAttributeStorage(LazyTemporalAttributeStorage.MissingRangeHandler<V> loader)` Instantiates a read only LazyTemporalAttributeStorage.
`LazyTemporalAttributeStorage(LazyTemporalAttributeStorage.MissingRangeHandler<V> loader, LazyTemporalAttributeStorage.ChangeHandler<V> writer)` Instantiates a read-write LazyTemporalAttributeStorage.

Method Summary
`void`	`beginAtomicOperation()` Tells the storage that the JTemporal client is calling a method that can result in multiples updates in the storage.
`void`	`clear()` Removes all the stored mappings.
`void`	`clearCache()`
`boolean`	`containsValue(java.lang.Object value)` Returns `true` if this map maps one or more Periods to the specified value.
`boolean`	`containsValue(java.lang.Object value, Period range)` Returns `true` if this map maps one or more Periods to the specified value, during the specified period.
`void`	`endAtomicOperation()` Tells the storage that an atomic operation has finished.
`CloseableIterator`	`entryIterator()` Iterates over all the entries of the storage.
`CloseableIterator`	`entryIterator(Period p)` Iterates over all the entries of the storage that intersects the period P.
`Period`	`firstPeriod()` Returns the first (lowest) period currently in this storage.
`Period`	`firstPeriod(Period p)` Returns the first (lowest) period currently in this storage, that intersects the given period.
`TimedObject`	`getEntry(Instant instant)` Returns the entry valid at the given instant, if any is found.
`TimedObject`	`getEntryEndingAt(Instant instant)` Returns the entry finishing exactly at the given instant, if any is found.
`TimedObject`	`getEntryStartingAt(Instant instant)` Returns the entry starting exactly at the given instant, if any is found.
`Period`	`getPeriod(Instant instant)` Returns the period that encloses the given instant, if any is found.
`java.lang.Object`	`getValue(Instant instant)` Returns the value to which this map maps the specified Instant.
`boolean`	`isEmpty()` Returns `true` if this storage does not contain objects.
`boolean`	`isEmpty(Period p)` Returns `true` if this storage does not contain objects intersecting the given period.
`Period`	`lastPeriod()` Returns the last (highest) period currently in this storage.
`Period`	`lastPeriod(Period p)` Returns the last (highest) period currently in this storage, that intersects the given period.
`CloseableIterator`	`periodIterator()` Iterates over all the periods of the storage.
`CloseableIterator`	`periodIterator(Period p)` Iterates over all the periods of the storage that intersects the period P.
`void`	`populated(Period p)` Called by the implementation of LazyTemporalAttributeStorage.MissingRangeHandler.populateRange(LazyTemporalAttributeStorage, Period) to to tell which Period (or additional Period) can now considered as complete in the cache.
`void`	`put(Period p, java.lang.Object value)` Stores a mapping (entry, tuple, row) composed by period and value.
`void`	`putInCache(Period p, V o)` Called by the implementation of LazyTemporalAttributeStorage.MissingRangeHandler.populateRange(LazyTemporalAttributeStorage, Period) to add entries in the cache.
`void`	`removeEntry(Period p)` Removes an entry composed by period and value previously stored.
`int`	`removeRange(Period range)` Removes all the entries whose period indersects the given period.
`int`	`size()` Returns the number of Period-value mappings in this map.
`int`	`size(Period p)` Returns the number of Period-value mappings in this map, for the given priod.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

LazyTemporalAttributeStorage

public LazyTemporalAttributeStorage(LazyTemporalAttributeStorage.MissingRangeHandler<V> loader)

Instantiates a read only LazyTemporalAttributeStorage.

Parameters:: loader -

LazyTemporalAttributeStorage

public LazyTemporalAttributeStorage(LazyTemporalAttributeStorage.MissingRangeHandler<V> loader,
                                    LazyTemporalAttributeStorage.ChangeHandler<V> writer)

Instantiates a read-write LazyTemporalAttributeStorage.

Parameters:: loader -

Method Detail

clearCache

public void clearCache()

putInCache

public void putInCache(Period p,
                       V o)

Called by the implementation of LazyTemporalAttributeStorage.MissingRangeHandler.populateRange(LazyTemporalAttributeStorage, Period) to add entries in the cache.
The semantics is the same as put(Period, Object), except that the entries are loaded in the cache only.

Parameters:: p - period with which the specified value is associated. Cannot be null.; o - value to be associated with the specified key. Cannot be null.
See Also:: put(Period, Object)

populated

public void populated(Period p)

Called by the implementation of LazyTemporalAttributeStorage.MissingRangeHandler.populateRange(LazyTemporalAttributeStorage, Period) to to tell which Period (or additional Period) can now considered as complete in the cache.