Squeak/Pharo binding for Snappy compression library
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README.md

README.md

Sqnappy

Squeak/Pharo binding for Snappy compression library. Sqnappy is using a VM plugin for calling Snappy C API. (It is not a pure Smalltalk implementation).

You can see these directories:

  • plugin-build
  • plugin build settings
  • plugin-binary
  • pre-built shared libraries (SnappyPlugin.dll, bundle, so, etc)
  • repository
  • Cypress style Smalltalk source tree

For MCZ packages, visit SmalltalkHub Sqnappy site.

Performance

Just a simple code snippet. But it would be helpful for showing Sqnappy's characteristics.

"## Test data ##"
originalBytes := Morph allSelectors asString asByteArray.
originalBytes size. "30363 bytes on my image"

"## Compressed size ##"
" GZipWriteStream "
originalBytes asString zipped size. "11036"
" Sqnappy"
(SnappyCore compress: originalBytes) size.  "17461 -- 1.6x bigger"

"## Round-trip time ##"
" GZipWriteStream/GZipReadStream "
[100 timesRepeat: [originalBytes asString zipped unzipped asByteArray]] timeToRun.  "487"
" Sqnappy "
[100 timesRepeat: [SnappyCore uncompress: (SnappyCore compress: originalBytes)]] timeToRun "45 -- 10.8x faster"

Features

  • Basic compress/uncompress API
  • Stream API with framing format support (interoperability was checked with snzip)
  • Custom stream format (.sqn - sqnappy)
    • Block size is changeable from 32k to 4M (default is 64k)
    • No CRC32C checking for speed
    • Data size is represented in big-endian

Usage

Basic:

"## Compress/Uncompress ##"
compressed := SnappyCore compress: data.
uncompressed := SnappyCore uncompress: compressed.

Streaming:

"## Streaming (write) ##"
wstrm := SnappyFraming sz writeStreamOn: ByteArray new.
wstrm nextPutAll: #[49 50 51 52 53 10 49 50 51 52 53 10].
wstrm nextPutAll: #[49 50 51 52 53 10 123 49 50 51 52 53 10 0].
compressed := wstrm contents.
wstrm close.
"## Streaming (read) ##"
rstrm := SnappyFraming sz readStreamOn: compressed.
uncompressed := rstrm contents.
rstrm close.
"## Streaming (partial read) ##"
rstrm := SnappyFraming sz readStreamOn: compressed.
[rstrm atEnd] whileFalse: [
  uncompressedPart := rstrm upTo: 10.
  Transcript cr; show: uncompressedPart asString
].
rstrm close.

Streaming with files: (This snippet is using FileMan for simplifying file access).

"## Compress 'SqueakV41.sources -> 'SqueakV41.sources.sqn' with Sqnappy format ##"
readStr := ('.' asDirectoryEntry / 'SqueakV41.sources') readStream binary.
writeEnt := '.' asDirectoryEntry / 'SqueakV41.sources.sqn'.
writer := SnappyFraming sqn writeStreamOn: writeEnt writeStream.
writer repeatWrite:[:w | w nextPutAll:(readStr next: w blockSize)] until:[readStr atEnd] finally:[:w | w close. readStr close].

"## Uncompress 'SqueakV41.sources.sqn -> 'SqueakV41.sources' ##"
readEnt := '.' asDirectoryEntry / 'SqueakV41.sources.sqn'.
reader := SnappyFraming sqn readStreamOn: readEnt readStream.
writeStr := ('.' asDirectoryEntry / 'SqueakV41-trip.sources') writeStream.
reader repeatReadUntilEnd:[:r | ] out: writeStr finally:[:r | r close. writeStr close].

On my windows laptop (Core-i5 2430M, Samsong SSD 840), Compressed file('SqueakV41.sources.sqn') was written in about 250 msecs. Uncompressed file('SqueakV41-trip.sources') was written in about 100 msecs. Original file size was 26,005,504 bytes. Compressed file size was 10,612,736 bytes.

Stream API enables you to handle pretty big data. I've also tested the code above with a big pg_dump file ( 1.3G - 1,304,485,888 bytes). There were no annoying GCs. Compressed size was 631,627,776 bytes. 9844 msecs for compress; 6496 msecs for uncompress.

Installation

  1. Copy the pre-built Snappy.dll (.so, .bundle) to your VM directory
  2. Load Sqnappy
"Squeak"
Installer squeaksource
    project: 'MetacelloRepository';
    install: 'ConfigurationOfSqnappy'. 
(Smalltalk at: #ConfigurationOfSqnappy) load.

"Pharo"
Gofer new
      url: 'http://smalltalkhub.com/mc/MasashiUmezawa/Sqnappy/main';
      package: 'ConfigurationOfSqnappy';
      load.
(Smalltalk at: #ConfigurationOfSqnappy) load.

Open TestRunner and see the results. If tests are red, please make sure step.1 was done properly.

Note: Plugin binaries were built for 32 bit Cog VM. For other VM (legacy VM, 64 bit VM, etc), probably you need to recompile plugin source by yourself.

License

MIT license