Tips for using Oodle as Efficiently as Possible

Tips for using Oodle as efficiently and robustly as possible. (wrst your game runtime loading + decoding only).

1. Use the new compressors (Kraken/Mermaid/Selkie/Hydra). Aside from being great performance, they have the most robust and well-tested fuzz safety.

2. Pass FuzzSafe_Yes to the OodleLZ_Decompress option. The KMS decoders are always internally fuzz safe. What the FuzzSafe_Yes option is add some checks to the initial header decode which will cause the decode to fail if the header byte has been tampered with to change it to a non-KMS compressor.

3. Use Oodle Core lib only, not Ext. Core lib is very light and tight. Core lib makes no threads, requires no init, and will do no allocations to decode (if you pass in the memory).

4. Disable Oodle's callbacks :

    OodlePlugins_SetAllocators(NULL,NULL);
    OodlePlugins_SetAssertion(NULL);
    OodlePlugins_SetPrintf(NULL);

(note that disabling the allocators only works because you are doing decoding only (no encoding) and because you do #5 below - pass in scratch memory for the decoder)

5. Because you disabled Oodle's access to an allocator, instead pass in the memory needed. You can ask the data for the compressor if you don't always know it.

    compressor = OodleLZ_GetChunkCompressor(in_comp,NULL);
                                    
    decoderMemorySize = OodleLZDecoder_MemorySizeNeeded(compressor,in_raw_length);
    decoderMemory = malloc( decoderMemorySize );

6. If possible keep the Decoder memory around or pull from some shared scratch space rather than allocating & freeing it every time.

7. If you're on a platform where Oodle is in a DLL or .so , sign it with a mechanism like authentisign to ensure it isn't tampered with.

8. If possible do async IO and use double-buffering to incrementally load data and decompress, so that you are maximally using the IO bus and the CPU at the same time. If loading and decoding large buffers, consider running the decoders "ThreadPhased".

9. If possible use Thread-Phased decoding on large buffers that can't be broken into multiple decodes. The most efficient use of threading always comes from running multiple unrelated encode/decodes simultaneously, rather than trying ti multi-thread a single encode/decode.

10. Use a mix of compressors to put your decode time where it helps the most. eg. use the slower compressors only when they get big size wins, and perhaps tune the compression to the game's latency needs - random access data that needs to get loaded as fast as possible, use faster decoders, background data that streams in slowly can use slower decoders. Hydra is the best way to do this, it will automatically measure decode speed and tune to maximize the space-speed tradeoff.

11. Don't load tiny buffers. Combine them into larger paging units.

12. Consider in-memory compressed data as a paging cache.

As always, feel free to contact me and ask questions.