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Snappy compressor/decompressor for Java
Java C++ Shell Python Scala Makefile Other

Merge pull request #120 from linux-on-ibm-z/develop-s390x

Fix SnappyOutputStreamTest for big-endian platforms
latest commit f38b91f18c
@xerial authored

README.md

The snappy-java is a Java port of the snappy http://code.google.com/p/snappy/, a fast C++ compresser/decompresser developed by Google.

Features

  • Fast compression/decompression around 200~400MB/sec.
  • Less memory usage. SnappyOutputStream uses only 32KB+ in default.
  • JNI-based implementation to achieve comparable performance to the native C++ version.
    • Although snappy-java uses JNI, it can be used safely with multiple class loaders (e.g. Tomcat, etc.).
  • Compression/decompression of Java primitive arrays (float[], double[], int[], short[], long[], etc.)
  • Portable across various operating systems; Snappy-java contains native libraries built for Window/Mac/Linux (64-bit). snappy-java loads one of these libraries according to your machine environment (It looks system properties, os.name and os.arch).
  • Simple usage. Add the snappy-java-(version).jar file to your classpath. Then call compression/decompression methods in org.xerial.snappy.Snappy.
  • Framing-format support (Since 1.1.0 version)
  • OSGi support
  • Apache License Version 2.0. Free for both commercial and non-commercial use.

Performance

Download

The current stable version is available from here:

Using with Maven

Add the following dependency to your pom.xml:

<dependency>
  <groupId>org.xerial.snappy</groupId>
  <artifactId>snappy-java</artifactId>
  <version>1.1.2-RC3</version>
  <type>jar</type>
  <scope>compile</scope>
</dependency>

Using with sbt

libraryDependencies += "org.xerial.snappy" % "snappy-java" % "1.1.2-RC3"

Usage

First, import org.xerial.snapy.Snappy in your Java code:

import org.xerial.snappy.Snappy;

Then use Snappy.compress(byte[]) and Snappy.uncompress(byte[]):

String input = "Hello snappy-java! Snappy-java is a JNI-based wrapper of "
     + "Snappy, a fast compresser/decompresser.";
byte[] compressed = Snappy.compress(input.getBytes("UTF-8"));
byte[] uncompressed = Snappy.uncompress(compressed);

String result = new String(uncompressed, "UTF-8");
System.out.println(result);

In addition, high-level methods (Snappy.compress(String), Snappy.compress(float[] ..) etc. ) and low-level ones (e.g. Snappy.rawCompress(.. ), Snappy.rawUncompress(..), etc.), which minimize memory copies, can be used.

Stream-based API

Stream-based compressor/decompressor SnappyOutputStream/SnappyInputStream are also available for reading/writing large data sets. SnappyFramedOutputStream/SnappyFramedInputStream can be used for the framing format.

Compatibility Notes

  • SnappyOutputStream and SnappyInputStream use [magic header:16 bytes]([block size:int32][compressed data:byte array])* format. You can read the result of Snappy.compress with SnappyInputStream, but you cannot read the compressed data generated by SnappyOutputStream with Snappy.uncompress. Here is the compatibility matrix of data foramt:
Write\Read Snappy.uncompress SnappyInputStream SnappyFramedInputStream
Snappy.compress ok ok x
SnappyOutputStream x ok x
SnappyFramedOutputStream x x ok

Setting classpath

If you have snappy-java-(VERSION).jar in the current directory, use -classpath option as follows:

$ javac -classpath ".;snappy-java-(VERSION).jar" Sample.java  # in Windows
or 
$ javac -classpath ".:snappy-java-(VERSION).jar" Sample.java  # in Mac or Linux

Public discussion group

Post bug reports or feature request to the Issue Tracker: https://github.com/xerial/snappy-java/issues

Public discussion forum is here: [Xerial Public Discussion Group)[http://groups.google.com/group/xerial?hl=en]

Building from the source code

See the installation instruction. Building from the source code is an option when your OS platform and CPU architecture is not supported. To build snappy-java, you need Git, JDK (1.6 or higher), g++ compiler (mingw in Windows) etc.

$ git clone https://github.com/xerial/snappy-java.git
$ cd snappy-java
$ make

When building on Solaris use

$ gmake

A file target/snappy-java-$(version).jar is the product additionally containing the native library built for your platform.

Building Linux x86_64 binary

snappy-java tries to static link libstdc++ to increase the availability for various Linux versions. However, standard distributions of 64-bit Linux OS rarely provide libstdc++ compiled with -fPIC option. I currently uses custom g++, compiled as follows:

$ cd work
$ wget (gcc-4.8.3 source)
$ tar xvfz (gcc-4.8.3.tar.gz)
$ cd gcc-4.8.3
$ ./contrib/download_prerequisites
$ cd ..
$ mkdir objdir
$ cd objdir
$ ../gcc-4.8.3/configure --prefix=$HOME/local/gcc-4.8.3 CXXFLAGS=-fPIC CFLAGS=-fPIC --enable-languages=c,c++
$ make
$ make install

This g++ build enables static linking of libstdc++. For more infomation on building GCC, see GCC's home page.

Building Linux s390/s390x binaries

Older snapshots of snappy contain a buggy config.h.in that does not work properly on some big-endian platforms like Linux on IBM z (s390/s390x). Building snappy-java on s390/s390x requires fetching the snappy source from GitHub, and processing the source with autoconf to obtain a usable config.h. On a RHEL s390x system, these steps produced a working 64-bit snappy-java build (the process should be similar for other distributions):

$ sudo yum install java-1.7.1-ibm-devel libstdc++-static-devel
$ export JAVA_HOME=/usr/lib/jvm/java-1.7.1-ibm-1.7.1.2.10-1jpp.3.el7_0.s390x
$ make USE_GIT=1 GIT_REPO_URL=https://github.com/google/snappy.git GIT_SNAPPY_BRANCH=master IBM_JDK_7=1

Cross-compiling for other platforms

The Makefile contains rules for cross-compiling the native library for other platforms so that the snappy-java JAR can support multiple platforms. For example, to build the native libraries for x86 Linux, x86 and x86-64 Windows, and soft- and hard-float ARM:

$ make linux32 win32 win64 linux-arm linux-armhf

If you append snappy to the line above, it will also build the native library for the current platform and then build the snappy-java JAR (containing all native libraries built so far).

Of course, you must first have the necessary cross-compilers and development libraries installed for each target CPU and OS. For example, on Ubuntu 12.04 for x86-64, install the following packages for each target:

  • linux32: sudo apt-get install g++-multilib libc6-dev-i386 lib32stdc++6
  • win32: sudo apt-get install g++-mingw-w64-i686
  • win64: sudo apt-get install g++-mingw-w64-x86-64
  • arm: sudo apt-get install g++-arm-linux-gnueabi
  • armhf: sudo apt-get install g++-arm-linux-gnueabihf

Unfortunately, cross-compiling for Mac OS X is not currently possible; you must compile within OS X.

If you are using Mac and openjdk7 (or higher), use the following option:

$ make native LIBNAME=libsnappyjava.dylib

For developers

snappy-java uses sbt (simple build tool for Scala) as a build tool. Here is a simple usage

$ ./sbt            # enter sbt console
> ~test            # run tests upon source code change
> ~test-only *     # run tests that matches a given name pattern  
> publishM2        # publish jar to $HOME/.m2/repository
> package          # create jar file
> findbugs         # Produce findbugs report in target/findbugs
> jacoco:cover     # Report the code coverage of tests to target/jacoco folder    

If you need to see detailed debug messages, launch sbt with -Dloglevel=debug option:

$ ./sbt -Dloglevel=debug

For the details of sbt usage, see my blog post: Building Java Projects with sbt

Miscellaneous Notes

Using snappy-java with Tomcat 6 (or higher) Web Server

Simply put the snappy-java's jar to WEB-INF/lib folder of your web application. Usual JNI-library specific problem no longer exists since snappy-java version 1.0.3 or higher can be loaded by multiple class loaders.


Snappy-java is developed by Taro L. Saito. Twitter @taroleo

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