org.apache.xerces.parsers

Class CachingParserPool

java.lang.Object

org.apache.xerces.parsers.CachingParserPool

public class CachingParserPool
extends Object

A parser pool that enables caching of grammars. The caching parser pool is constructed with a specific symbol table and grammar pool that has already been populated with the grammars used by the application.

Once the caching parser pool is constructed, specific parser instances are created by calling the appropriate factory method on the parser pool.

Note: There is a performance penalty for using a caching parser pool due to thread safety. Access to the symbol table and grammar pool must be synchronized to ensure the safe operation of the symbol table and grammar pool.

Note: If performance is critical, then another mechanism needs to be used instead of the caching parser pool. One approach would be to create parser instances that do not share these structures. Instead, each instance would get its own copy to use while parsing. This avoids the synchronization overhead at the expense of more memory and the time required to copy the structures for each new parser instance. And even when a parser instance is re-used, there is a potential for a memory leak due to new symbols being added to the symbol table over time. In other words, always take caution to make sure that your application is thread-safe and avoids leaking memory.

Version:

$Id$

Author:

Andy Clark, IBM

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CachingParserPool.ShadowedGrammarPool Shadowed grammar pool.
static class	CachingParserPool.SynchronizedGrammarPool Synchronized grammar pool.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	DEFAULT_SHADOW_GRAMMAR_POOL Default shadow grammar pool (false).
static boolean	DEFAULT_SHADOW_SYMBOL_TABLE Default shadow symbol table (false).
protected boolean	fShadowGrammarPool Shadow the grammar pool for new parser instances.
protected boolean	fShadowSymbolTable Shadow the symbol table for new parser instances.
protected XMLGrammarPool	fSynchronizedGrammarPool Grammar pool.
protected SymbolTable	fSynchronizedSymbolTable Symbol table.

Constructor Summary

Constructors

Constructor and Description
CachingParserPool() Default constructor.
CachingParserPool(SymbolTable symbolTable, XMLGrammarPool grammarPool) Constructs a caching parser pool with the specified symbol table and grammar pool.

Method Summary

Methods

Modifier and Type	Method and Description
DOMParser	createDOMParser() Creates a new DOM parser.
SAXParser	createSAXParser() Creates a new SAX parser.
SymbolTable	getSymbolTable() Returns the symbol table.
XMLGrammarPool	getXMLGrammarPool() Returns the grammar pool.
void	setShadowSymbolTable(boolean shadow) Sets whether new parser instance receive shadow copies of the main symbol table.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_SHADOW_SYMBOL_TABLE

public static final boolean DEFAULT_SHADOW_SYMBOL_TABLE

Default shadow symbol table (false).

See Also:

Constant Field Values

DEFAULT_SHADOW_GRAMMAR_POOL

public static final boolean DEFAULT_SHADOW_GRAMMAR_POOL

Default shadow grammar pool (false).

See Also:

Constant Field Values

fSynchronizedSymbolTable

protected SymbolTable fSynchronizedSymbolTable

Symbol table. The symbol table that the caching parser pool is constructed with is automatically wrapped in a synchronized version for thread-safety.

fSynchronizedGrammarPool

protected XMLGrammarPool fSynchronizedGrammarPool

Grammar pool. The grammar pool that the caching parser pool is constructed with is automatically wrapped in a synchronized version for thread-safety.

fShadowSymbolTable

protected boolean fShadowSymbolTable

Shadow the symbol table for new parser instances. If true, new parser instances use shadow copies of the main symbol table and are not allowed to add new symbols to the main symbol table. New symbols are added to the shadow symbol table and are local to the parser instance.

fShadowGrammarPool

protected boolean fShadowGrammarPool

Shadow the grammar pool for new parser instances. If true, new parser instances use shadow copies of the main grammar pool and are not allowed to add new grammars to the main grammar pool. New grammars are added to the shadow grammar pool and are local to the parser instance.

Constructor Detail

CachingParserPool

public CachingParserPool()

Default constructor.

CachingParserPool

public CachingParserPool(SymbolTable symbolTable,
                 XMLGrammarPool grammarPool)

Constructs a caching parser pool with the specified symbol table and grammar pool.

Parameters:

symbolTable - The symbol table.

grammarPool - The grammar pool.

Method Detail

getSymbolTable

public SymbolTable getSymbolTable()

Returns the symbol table.

getXMLGrammarPool

public XMLGrammarPool getXMLGrammarPool()

Returns the grammar pool.

setShadowSymbolTable

public void setShadowSymbolTable(boolean shadow)

Sets whether new parser instance receive shadow copies of the main symbol table.

Parameters:

shadow - If true, new parser instances use shadow copies of the main symbol table and are not allowed to add new symbols to the main symbol table. New symbols are added to the shadow symbol table and are local to the parser instance. If false, new parser instances are allowed to add new symbols to the main symbol table.

createDOMParser

public DOMParser createDOMParser()

Creates a new DOM parser.

createSAXParser

public SAXParser createSAXParser()

Creates a new SAX parser.