Module zstd_codec 

Zstd compression codec for cold/archived partitions.

Higher compression ratio than LZ4 (~5-10x for structured data), slower decompression. Best for sealed partitions that are read infrequently.

Platform strategy:

• Native: zstd crate (C libzstd, fastest)
• WASM: ruzstd crate (pure Rust decoder, no C dependency)

Wire format:

[4 bytes] uncompressed size (LE u32)
[1 byte]  compression level used
[N bytes] Zstd frame (standard format, decodable by any Zstd implementation)

The 5-byte header prepended to the standard Zstd frame allows us to pre-allocate the output buffer on decode and store the level for metadata.

Structs

ZstdDecoder

Zstd decoder wrapper.

ZstdEncoder

Streaming Zstd encoder. Accumulates data and compresses on finish().

Constants

DEFAULT_LEVEL

Default Zstd compression level (3 = good balance of speed and ratio).

HIGH_LEVEL

High compression level for cold storage (19 = near-maximum ratio).

Functions

compression_level

Get the compression level from the header.

decode

Decompress Zstd-compressed bytes.

encode

Compress raw bytes using Zstd at the default level (3).

encode_with_level

Compress raw bytes using Zstd at a specific level (1-22).

uncompressed_size

Get the uncompressed size from the header without decompressing.