https://github.com/romix/java-concurrent-hash-trie-map

Java port of a concurrent trie hash map implementation from the Scala collections library
https://github.com/romix/java-concurrent-hash-trie-map

Last synced: 5 months ago
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Java port of a concurrent trie hash map implementation from the Scala collections library

• Host: GitHub
• URL: https://github.com/romix/java-concurrent-hash-trie-map
• Owner: romix
• Created: 2012-09-11T13:43:17.000Z (over 13 years ago)
• Default Branch: master
• Last Pushed: 2020-10-13T08:29:38.000Z (about 5 years ago)
• Last Synced: 2025-06-28T20:08:01.176Z (6 months ago)
• Language: Java
• Size: 141 KB
• Stars: 152
• Watchers: 15
• Forks: 26
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • License: LICENSE-2.0.html

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README

          
About

=============================

This is a Java port of a concurrent trie hash map implementation from the Scala collections library. It is almost a line-by-line 

conversion from Scala to Java.

Idea + implementation techniques can be found in these reports written by Aleksandar Prokopec:

   * http://infoscience.epfl.ch/record/166908/files/ctries-techreport.pdf - this is a nice introduction to Ctries, along with a correctness proof

   * http://lamp.epfl.ch/~prokopec/ctries-snapshot.pdf - a more up-to-date writeup which describes the snapshot operation

The original Scala implementation can be found here and is a part of scala.collection.concurrent:

   *   [Scala implementation](https://github.com/scala/scala/blob/930c85d6c96507d798d1847ea078eebf93dc0acb/src/library/scala/collection/concurrent/TrieMap.scala)

Some of the tests and implementation details were borrowed from this project:

   *  https://github.com/flegall/concurrent-hash-trie

Implementation status : 

   *   The given implementation is complete and implements all features of the original Scala implementation including support for 

   snapshots.

   *   Wherever necessary, code was adapted to be more easily usable in Java, e.g. it returns Objects instead of Option as 

   many methods of Scala's collections do.   

   *   This class implements all the ConcurrentMap & Iterator methods and passes all the tests. Can be used as a drop-in replacement

       for usual Java maps, including ConcurrentHashMap.

What is a concurrent trie hash map also known as ctrie?

========================================================

ctrie is a lock-Free Concurrent Hash Array Mapped Trie.

A concurrent hash-trie or Ctrie is a concurrent thread-safe lock-free implementation of a hash array mapped trie.

 

It is used to implement the concurrent map abstraction. It has particularly scalable concurrent insert and remove operations 

and is memory-efficient. 

It supports O(1), atomic, lock-free snapshots which are used to implement linearizable lock-free size, iterator and clear operations. 

The cost of evaluating the (lazy) snapshot is distributed across subsequent updates, thus making snapshot evaluation horizontally scalable.

The original Scala-based implementation of the Ctrie is a part of the Scala standard library since the version 2.10.

More info about Ctries:

- http://infoscience.epfl.ch/record/166908/files/ctries-techreport.pdf - this is a nice introduction to Ctries, along with a correctness proof

- http://lamp.epfl.ch/~prokopec/ctries-snapshot.pdf - a more up-to-date writeup (more coherent with the current version of the code) which describes the snapshot operation

       

License

===============================

This library is licensed under the Apache 2.0 license.

Usage

===============================

Usage of this library is very simple. Simply import the class com.romix.scala.collection.concurrent.TrieMap and use it as a usual Map.

    

    import com.romix.scala.collection.concurrent.TrieMap;

    

    Map myMap = new TrieMap  ();

    myMap.put("key", "value");

    

Building the library

===============================

Use a usual `mvn clean install`

Using the library with Maven projects

=====================================

The prebuilt binaries of the library are available from Maven central. Please use the following dependency in your POM files:

		

			com.github.romix

			java-concurrent-hash-trie-map

			0.2.23

		

External dependencies

=====================================

This library is self-contained. It does not depend on any additional libraries. In particular, it does not require the rather big Scala's 

standard library to be used.