xapi.collect.impl

Class MultithreadedStringTrie<E>

java.lang.Object

xapi.collect.impl.MultithreadedStringTrie<E>

Type Parameters:

E -

All Implemented Interfaces:

HasPrefixed<E>, PrefixedMap<E>

Direct Known Subclasses:

CharPoolTrie

public class MultithreadedStringTrie<E>
extends Object
implements PrefixedMap<E>

NSFW This somewhat monsterous Trie implementation is a work in progress.

It exists in a cleaner form in the labs module, but it was good enough to act as a high-performance solution in multi-threaded environments.

It is really only used for our classpath scanner, which can beat java.util concurrent maps in heavily threaded enviros

Trie walking locks safely, but with minimal hold times, so contention during concurrent operations will only occur if the keys overlap. Once one thread is ahead of another, it will stay ahead of others.

This class should NOT be used anywhere that doesn't explicitly need Trie behavior in multi-threaded enviros. It's not optimized for lookup time yet.

Application-wide, java-package based keys are good candidates for StringTrie.

Production Trie versions will be suitable for tasks like type-ahead, with O(log(m)) lookup, where m = string length instead of n = collection size.

The in-progress upgrade to this class will include array-based deep node support, so nodes with more than two branches can do faster lookup.

Author:

"James X. Nelson (james@wetheinter.net)"

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	MultithreadedStringTrie.Edge Our Edge class is one node in the Trie graph.
protected class	MultithreadedStringTrie.Itr

Field Summary

Fields

Modifier and Type	Field and Description
protected MultithreadedStringTrie.Edge	root

Constructor Summary

Constructors

Constructor and Description
MultithreadedStringTrie()

Method Summary

Modifier and Type	Method and Description
void	compress(CharPool charPoolTrie)
protected void	doPut(MultithreadedStringTrie.Edge into, char[] key, int index, int end, E value)
Iterable<E>	findPrefixed(String prefix)
E	get(char[] key)
E	get(char[] key, int pos, int end)
E	get(Chars keys, int pos, int end)
E	get(String key)
protected void	lock(MultithreadedStringTrie.Edge into, boolean ownsParent)
protected MultithreadedStringTrie.Edge	newEdge()
protected MultithreadedStringTrie.Edge	newEdge(char[] key, int index, int end, E value)
protected MultithreadedStringTrie.Edge	newEdgeGreater(MultithreadedStringTrie.Edge previous, int keyMax, char[] existing, int matchesTo, char[] key, int keyIndex, int keyEnd, E value)
protected MultithreadedStringTrie.Edge	newEdgeLesser(MultithreadedStringTrie.Edge previous, int keyMax, char[] existing, int matchesTo, char[] key, int keyIndex, int keyEnd, E value)
protected E	onEmpty(MultithreadedStringTrie.Edge e, Chars keys, int pos, int end)
void	put(char[] key, int start, int end, E value)
void	put(String key, E value)
protected E	returnValue(MultithreadedStringTrie.Edge e, Chars keys, int pos, int end)
String	toString()
protected void	unlock(MultithreadedStringTrie.Edge into, boolean ownsParent)

Methods inherited from class java.lang.Object

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

Field Detail

root

protected final MultithreadedStringTrie.Edge root

Constructor Detail

MultithreadedStringTrie

public MultithreadedStringTrie()

Method Detail

put

public void put(char[] key,
                int start,
                int end,
                E value)

put

public void put(String key,
                E value)

Specified by:

put in interface PrefixedMap<E>

doPut

protected void doPut(MultithreadedStringTrie.Edge into,
                     char[] key,
                     int index,
                     int end,
                     E value)

newEdge

protected MultithreadedStringTrie.Edge newEdge()

newEdge

protected MultithreadedStringTrie.Edge newEdge(char[] key,
                                               int index,
                                               int end,
                                               E value)

newEdgeLesser

protected MultithreadedStringTrie.Edge newEdgeLesser(MultithreadedStringTrie.Edge previous,
                                                     int keyMax,
                                                     char[] existing,
                                                     int matchesTo,
                                                     char[] key,
                                                     int keyIndex,
                                                     int keyEnd,
                                                     E value)

newEdgeGreater

protected MultithreadedStringTrie.Edge newEdgeGreater(MultithreadedStringTrie.Edge previous,
                                                      int keyMax,
                                                      char[] existing,
                                                      int matchesTo,
                                                      char[] key,
                                                      int keyIndex,
                                                      int keyEnd,
                                                      E value)

lock

protected void lock(MultithreadedStringTrie.Edge into,
                    boolean ownsParent)

Parameters:

into - - The edge to lock

ownsParent - - Whether we already own an explicit lock on the parent.

unlock

protected void unlock(MultithreadedStringTrie.Edge into,
                      boolean ownsParent)

Parameters:

into - - The edge to lock

ownsParent - - If true, you are already synchronized on into.

cursor - - Whatever object you returned when you locked. This method is a stub for more sophisticated subclasses of StringTrie, which may need to perform proper concurrent locking, or event dispatch. It is called in the finally block of whatever code ran lock(Edge, boolean). If you use Edge into.wait(0, nanos) in lock(), now would be a great time to call into into.notify() :)

toString

public String toString()

Overrides:

toString in class Object

get

public E get(String key)

Specified by:

get in interface PrefixedMap<E>

get

public E get(char[] key)

get

public E get(char[] key,
             int pos,
             int end)

get

public E get(Chars keys,
             int pos,
             int end)

findPrefixed

public Iterable<E> findPrefixed(String prefix)

Specified by:

findPrefixed in interface HasPrefixed<E>

compress

public void compress(CharPool charPoolTrie)

returnValue

protected E returnValue(MultithreadedStringTrie.Edge e,
                        Chars keys,
                        int pos,
                        int end)

onEmpty

protected E onEmpty(MultithreadedStringTrie.Edge e,
                    Chars keys,
                    int pos,
                    int end)