Module com.aoindustries.aoserv.client

Package com.aoindustries.aoserv.client

Class FilesystemCachedTable<K,V extends FilesystemCachedObject<K,V>>

java.lang.Object

com.aoindustries.aoserv.client.AoservTable<K,V>

com.aoindustries.aoserv.client.FilesystemCachedTable<K,V>

All Implemented Interfaces:

FileListObjectFactory<V>, Table<V>, Iterable<V>

Direct Known Subclasses:

DistroFileTable

public abstract class FilesystemCachedTable<K,V extends FilesystemCachedObject<K,V>>
extends AoservTable<K,V>
implements FileListObjectFactory<V>

A FilesystemCachedTable stores all of the available FilesystemCachedObjects in a temporary file and performs all subsequent data access locally. The server notifies the client when a table is updated, and the caches are then invalidated. Once invalidated, the data is reloaded upon next use.

The file format is a simple fixed record length format.

TODO: It is possible to use the same column sorting technique to implement the getIndexedRows method from AoservTable.

Author:

AO Industries, Inc.

Nested Class Summary

Nested classes/interfaces inherited from class com.aoindustries.aoserv.client.AoservTable

AoservTable.OrderBy

Field Summary

Fields inherited from class com.aoindustries.aoserv.client.AoservTable

ASCENDING, connector, DESCENDING

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	FilesystemCachedTable(AoservConnector connector, Class<V> clazz)

Method Summary

Modifier and Type	Method	Description
void	clearCache()	Clears the cache, freeing up memory.
V	createInstance()
protected abstract int	getRecordLength()
final List<V>	getRows()	Gets the complete list of objects in the table.
List<V>	getRowsCopy()	Gets a modifiable copy of the rows, which may then be manipulated, such as for sorting.
protected ComparisonSortAlgorithm<Object>	getSortAlgorithm()	FastQSort accesses the disk file less than other algorithms, and does not load all the objects into memory at once like the default Java merge sort.
protected final V	getUniqueRowImpl(int col, Object value)	Gets a row given a unique column value.
final boolean	isLoaded()	Checks if the table is loaded.

Methods inherited from class com.aoindustries.aoserv.client.AoservTable

addProgressListener, addTableListener, addTableListener, addTableLoadListener, get, getCachedRowCount, getConnector, getDefaultOrderBy, getDefaultOrderBySqlExpressions, getIndexedRows, getIndexedRows, getMap, getNewObject, getObject, getObjects, getObjects, getObjects, getObjectsNoProgress, getObjectsNoProgress, getSize, getTableId, getTableName, getTableSchema, getUniqueRow, getUniqueRow, getUniqueRow, getUniqueRow, handleCommand, hasAnyTableListener, hasTableListener, isEmpty, iterator, printTable, removeProgressListener, removeTableListener, removeTableLoadListener, size, sortIfNeeded, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Details

FilesystemCachedTable

protected FilesystemCachedTable(AoservConnector connector,
 Class<V> clazz)

Method Details

getRecordLength

protected abstract int getRecordLength()

clearCache

public void clearCache()

Clears the cache, freeing up memory. The data will be reloaded upon next use.

Overrides:

clearCache in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

getRows

public final List<V> getRows()
                      throws IOException,
SQLException

Gets the complete list of objects in the table. This list is unmodifiable and will not ever be changed. Newer data will be contained in new lists so that any calling code sees a snapshot of the code and may safely assume the data is constant as long as the code uses the same reference to List returned here.

Specified by:

getRows in interface Table<K>

Overrides:

getRows in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

Returns:

a List containing all of the rows

Throws:

IOException - if unable to access the server

SQLException - if unable to access the database

See Also:

• AoservTable.getRowsCopy()

getRowsCopy

public List<V> getRowsCopy()
                    throws IOException,
SQLException

Description copied from class: AoservTable

Gets a modifiable copy of the rows, which may then be manipulated, such as for sorting.

This gives the table implementation a way to create a defensive copy most efficient to its underlying storage mechanism.

Note: It is best to use AoservTable.getSortAlgorithm() when sorting rows, as the choice of sorting can be very important when objects are pulled from non-heap source like filesystem-based objects. It is very easy for the sort itself to end up pulling all objects into heap.

Specified by:

getRowsCopy in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

Throws:

IOException

SQLException

See Also:

• AoservTable.getRows()
• AoservTable.getSortAlgorithm()

getSortAlgorithm

protected ComparisonSortAlgorithm<Object> getSortAlgorithm()

FastQSort accesses the disk file less than other algorithms, and does not load all the objects into memory at once like the default Java merge sort.

Overrides:

getSortAlgorithm in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

getUniqueRowImpl

protected final V getUniqueRowImpl(int col,
 Object value)
                            throws IOException,
SQLException

Description copied from class: AoservTable

Gets a row given a unique column value.

Specified by:

getUniqueRowImpl in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

Parameters:

col - the column index to search

value - when null, no row is matched, even if there is a single row with a uniquely null value

Throws:

IOException

SQLException

isLoaded

public final boolean isLoaded()

Description copied from class: AoservTable

Checks if the table is loaded. A table is considered loaded when accessing any part of it will be done entirely locally, avoiding any network traffic.

Overrides:

isLoaded in class AoservTable<K,V extends FilesystemCachedObject<K,V>>

createInstance

public V createInstance()
                 throws IOException

Specified by:

createInstance in interface FileListObjectFactory<K>

Throws:

IOException