Motivation:
1. Hash function in the Snappy encoding is wrong probably: used '+' instead of '*'. See the reference implementation [1].
2. Size of the hash table is calculated, but not applied.
Modifications:
1. Fix hash function: replace addition by multiplication.
2. Allocate hash table with calculated size.
3. Use an `Integer.numberOfLeadingZeros` trick for calculate log2.
4. Release buffers in tests.
Result:
1. Better compression. In the test `encodeAndDecodeLongTextUsesCopy` now compressed size is 175 instead of 180 before this change.
2. No redundant allocations for hash table.
3. A bit faster the calc of shift (less an expensive math operations).
[1] 513df5fb5a/snappy.cc (L67)
If you are on Linux, you need additional development packages installed on your system, because you'll build the native transport.
Note that this is build-time requirement. JDK 5 (for 3.x) or 6 (for 4.0+) is enough to run your Netty-based application.
Branches to look
Development of all versions takes place in each branch whose name is identical to <majorVersion>.<minorVersion>. For example, the development of 3.9 and 4.0 resides in the branch '3.9' and the branch '4.0' respectively.
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