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https://github.com/pantheontech/triemap
Java port of a concurrent trie hash map implementation from the Scala collections library
https://github.com/pantheontech/triemap
Last synced: 27 days 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/pantheontech/triemap
- Owner: PANTHEONtech
- License: apache-2.0
- Created: 2018-08-09T11:28:17.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2024-06-30T22:54:41.000Z (6 months ago)
- Last Synced: 2024-07-04T18:01:45.390Z (6 months ago)
- Language: Java
- Homepage:
- Size: 650 KB
- Stars: 27
- Watchers: 6
- Forks: 9
- Open Issues: 12
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Security: SECURITY.md
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## About
This is a Java port of a concurrent trie hash map implementation from the Scala collections library. It used to be an almost line-by-line
conversion from Scala to Java. These days it has been refactored to be Java 8 friendly and make some original assertions impossible via
refactoring.
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 code origins can be tracked through these links:
* [Original Java port](https://github.com/romix/java-concurrent-hash-trie-map)
* [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.
* The code take advantage of Java 8 to supplant Scala constructs
* The implementation is a Java 9+ JPMS module and can easily be depended upon by other modules
## 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
## Required Java versions
There are multiple release trains of this library:
* Versions 1.1.x require Java 8 or later
* Versions 1.2.x require Java 11 or later
* Versions 1.3.x require Java 17 or later
## License
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## Usage
Usage of this library is very simple. Simply import the class tech.pantheon.triemap.TrieMap and use it as a usual Map.
```java
import tech.pantheon.triemap.TrieMap;
Map myMap = TrieMap.create();
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:
```xml
tech.pantheon.triemap
triemap
1.3.0
```
## 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.
## Contributing
All contributions are welcome! The mechanics follows GitHub norms: we use GH issues to track bugs and improvements. In terms of coding style,
the project follows OpenDaylight's code style -- which is a combination of Google's style guidelines and a few tweaks here and there -- these
are enforced by CheckStyle. Each code contribution should have an attached unit test, for bug fixes this is a strict requirement.
We are also using SpotBugs for static code analysis and prefer no @SuppressFBWarnings. If a suppression is needed, its scope must be minimal
and it must carry a justification.