fkjellberg opened a new pull request, #812:
URL: https://github.com/apache/commons-compress/pull/812
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This PR replaces the `BinaryTree` Huffman decoder with the new canonical
`HuffmanDecoder` already used by bzip2 and deflate64. Running the existing
benchmark test shows a small performance gain.
`BinaryTree` implementation:
```
Benchmark Mode Cnt Score
Error Units
Lh5CompressorInputStreamBenchmark.testDecompress avgt 25 1542,895 ±
41,839 us/op
```
`LhaHuffmanDecoder` implementation:
```
Benchmark Mode Cnt Score
Error Units
Lh5CompressorInputStreamBenchmark.testDecompress avgt 25 1515,176 ±
41,576 us/op
```
The main benefit of switching to the `HuffmanDecoder` apart from better code
reuse is lower RAM usage. For the benchmark test, the `BinaryTree`
implementation allocated 131,068 and 4,092 bytes to hold the two huffman trees
during decompression while the `HuffmanDecoder` allocates 1,116 and 84 bytes.
The `BinaryTree` implementation was originally copied from the zip package
and adapted for LHA. The original class is still used by
`ExplodingInputStream`, and I think it's worth investigating whether it could
be replaced by `HuffmanDecoder` as well.
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