com.allanbank.mongodb.bson.io

Class StringDecoderCache

java.lang.Object

com.allanbank.mongodb.bson.io.AbstractStringCache

com.allanbank.mongodb.bson.io.StringDecoderCache

public class StringDecoderCache
extends AbstractStringCache

StringDecoderCache provides a cache for decoding strings.

This class is thread safe. Thread safety is achieved by maintaining two data structures. The first is a map of seen strings to the number of times the string has been seen. The map is maintained by the base class: AbstractStringCache. The second structure is a trie of the cached byte[] to the decoded string.

API Warning:

This class is NOT part of the drivers API. This class may be mutated in incompatible ways between any two releases of the driver.

Copyright ©:

2014, Allanbank Consulting, Inc., All Rights Reserved

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	StringDecoderCache.TrieCache A fast cache for bytes to decoded strings.

Nested classes/interfaces inherited from class com.allanbank.mongodb.bson.io.AbstractStringCache

AbstractStringCache.ReverseIntegerComparator

Field Summary

Fields inherited from class com.allanbank.mongodb.bson.io.AbstractStringCache

DEFAULT_MAX_CACHE_ENTRIES, DEFAULT_MAX_CACHE_LENGTH, MAX_MULTIPLIER, myMaxCacheLength, myMaxCachEntries, myMaxCachEntriesMultiplier, mySeen, myUseCount

Constructor Summary

Constructors

Constructor and Description
StringDecoderCache() Creates a new TrieStringCache.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	clear() Clears the cache.
String	find(byte[] source, int offset, int length) Decode a string of a known length.
protected void	rebuildCache() Rebuilds the cache from the current collection of seen entries.

Methods inherited from class com.allanbank.mongodb.bson.io.AbstractStringCache

buildCacheGroups, getMaxCacheEntries, getMaxCacheLength, setMaxCacheEntries, setMaxCacheLength, used

Methods inherited from class java.lang.Object

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

Constructor Detail

StringDecoderCache

public StringDecoderCache()

Creates a new TrieStringCache.

Method Detail

find

public String find(byte[] source,
          int offset,
          int length)
            throws StreamCorruptedException,
                   EOFException

Decode a string of a known length. The last byte should be a zero byte and will not be included in the decoded string.

Parameters:

source - The source of the bytes in the string.

offset - The offset of the first byte to decode.

length - The length of the string to decode with a terminal zero byte.

Returns:

The decoded string.

Throws:

StreamCorruptedException - On the decoding of the string failing.

EOFException - On the array not containing enough bytes to decoded.

clear

protected void clear()

Clears the cache.

Overrides:

clear in class AbstractStringCache

rebuildCache

protected void rebuildCache()

Rebuilds the cache from the current collection of seen entries.

Specified by:

rebuildCache in class AbstractStringCache