Package org.smooks.engine.delivery.sax.ng.org.apache.xerces.parsers

Class 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

    • 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.