Purpose

Tr13 is a library for constructing and using read-only compact (memory-efficient) in-memory trie data structures, using raw (byte-sequences, byte[]) keys and values. Raw values can be automatically converted to/from basic JDK types such as java.lang.String. Resulting tries are "raw", in that they are stored as raw byte sequences (ByteBuffer, off-heap or in-heap, or byte[]), meaning that garbage-collection overhead should be minimal as the main data area is either off-heap (for native or mmap'ed ByteBuffers), or a single byte[].

Main benefits for using such tries is both relatively low memory usage (typically 20 - 35% less than raw input size) and low GC impact.

Development

Mailing list: http://groups.google.com/group/ning-tr13-users

Usage

Tries need to be built in lexicographic order, so pre-sorting may be needed. For that, you may want to check out Java Merge-sort project. Key and value types

Building is done in two steps:

1. Construct raw trie structure in streaming fashion, either into a memory buffer (like ByteArrayOutputStream), or a File.
2. Construct actual trie from serialized raw sequence (File, byte[]).

Two-phase processing is needed since the actual result size is not known in advance.

Sample

This tr13 from LevelDB gist shows simple usage.

Documentation

Check out [https://github.com/ning/tr13/wiki]