ParPar is a high performance, multi-threaded PAR2 creation tool and library for node.js. ParPar does not verify or repair files, only creates redundancy. ParPar is a completely new, from ground-up, implementation, which does not use components from existing PAR2 implementations.
ParPar provides three main things:
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Command line tool for creating PAR2 files, like what par2cmdline does
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High level JS API, with a similar interface to the command line tool
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Low level JS API, providing a high degree of control over the creation process
ParPar is currently still very much a work in progress, is not fully implemented and various issues still need to be solved. Please take this into consideration before using this tool for any non-experimental purposes.
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all main packets from the PAR2 specification
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unicode filename/comment support
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asychronous calculations and I/O
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multi-threading via OpenMP
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multiple fast calculation implementations leveraging x86 (SSE2, SSSE3, AVX2, AVX512BW, GFNI) and ARM (NEON) SIMD capabilities, automatically selecting the best routine for the CPU (see benchmark comparisons)
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multi-buffer (SIMD) MD5 implementation and accelerated CRC32 computation
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single read pass on source files if memory constraints allow (no separate hashing pass required)
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chunking support for memory constrained situations or for generating large amounts of recovery data
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minimum chunk size restrictions to avoid heavy I/O seeking when memory is limited
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cross-platform support
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completely different implementation to all the par2cmdline forks, using fresh new ideas and approaches :)
As mentioned above, ParPar is still under development. Some features currently not implemented include:
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improve CLI handling, i.e. better interface
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improve library interface, plus documentation
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better handling of input buffering and processing chunks based on CPU cache size
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improve handling of extremely large (e.g. gigabyte sized) slice sizes
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various other tweaks
Here’s a list of features currently not in ParPar, and may never be supported:
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Support for external recovery data or packed slices (I don’t think any PAR2 client supports this)
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Verify/repair PAR2
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Some optimisations in weird edge cases, such as using slice sizes significantly larger than all input data
I needed a flexible library for creating PAR2 files, in particular, one which isn’t tied to the notion of on-disk files. ParPar library allows generating PAR2 from “immaterial files”, and the output doesn’t have to be written to disk.
Also, all the fast PAR2 implementations seem to be Windows only; ParPar provides a solution for high performance PAR2 creation on Linux (and probably other) systems (without Wine) and it also works on Windows, as well as non-x86 platforms (i.e. ARM).
Pre-packaged Windows builds with Node 8.x may be found on the releases page if I can be bothered to provide them.
If NPM is installed (usually comes bundled with node.js), the following command can be used to install ParPar:
npm install -g @animetosho/parpar
You’ll then be able to run ParPar via the parpar command.
If the npm command isn’t available, it can probably be installed via your
package manager (apt-get install npm for Debian), or see the node.js
website.
If you get a gyp ERR! stack Error: EACCES: permission denied error when installing, try the following command instead:
npm install -g @animetosho/parpar --unsafe-perm
You can then later uninstall ParPar via:
npm uninstall -g @animetosho/parpar
Note that installing from NPM essentially compiles from source, so see issues listed in the following section if the install is failing on the build step.
For building you’ll need node.js (0.10.x or later), node-gyp (can be obtained
via npm install -g node-gyp command if NPM is available; may be in package
managers otherwise) and relevant build tools (i.e. MS Visual C++ for Windows,
GCC/Clang family otherwise). After you have the dependencies, the following
commands can be used to build:
node-gyp rebuild
npm install
This sets up ParPar to be run from the bin/parpar.js file (i.e. via node bin/parpar.js command). If you want it to be globally accessible via the parpar command, the process is OS dependent. On Linux, you can usually create a symlink named parpar in a location specified in the PATH environment variable, to bin/parpar.js (e.g. ln -s bin/parpar.js /usr/bin/parpar). On Windows, either add the bin folder to your PATH environment, or copy bin/parpar.cmd to a PATH specified directory and edit the paths appropriately in this copy of parpar.cmd.
Note, Windows builds are always compiled with SSE2 support. If you can’t have
this, delete all instances of "msvs_settings": {"VCCLCompilerTool": {"EnableEnhancedInstructionSet": "2"}}, in binding.gyp before compiling.
Relatively recent compilers (any supported compiler released in the last ~4 years should work) are needed if AVX support is desired. AVX512 support requires even newer compilers (GCC 5+, MSVC 2017 or later etc).
If you do not have NPM installed, ParPar can be built easily if your system's package manager has the necessary packages.
Debian 8 is such a system (should also be fine on Ubuntu 14.04), and here's how APT can be used:
apt-get install nodejs node-gyp node-async
node-gyp rebuild
Note that you'll also need node-yencode; follow the instructions here on how to build it. After building it, create a folder named node_modules and place the folder yencode in there.
Currently ParPar doesn't have proper runtime dispatch for calculation kernels on
GCC/Clang compilers (runtime dispatch on Windows (MSVC) does work).
This means that compilation is always done with the -march=native switch. The
build script will try to auto-detect whether this is supported by the compiler,
and avoid the flag if it's unavailable, but this means that the build may not be
correctly optimized if your version of GCC/Clang doesn't recognize the native
CPU architecture.
This also means that portable builds from GCC/Clang are currently unsupported.
ParPar’s multi-threading support requires OpenMP. If ParPar is compiled without
OpenMP, it will only ever run on 1 thread. OpenMP is usually available in most
compilers that you’d likely use. On some systems, you may need to ensure that the libomp-dev package is installed.
It appears that the default compiler in MacOSX does not include OpenMP support
(at time of writing). If this is the case, you may need to fetch another build
of the C++ compiler which has OpenMP support (e.g. clang/gcc from places like
homebrew/macports) and override the CXX environment variable when installing.
Due to security changes in OSX 10.15, libraries may require code signing to work. To deal with this, you’ll either need to disable this security option or codesign the built .node module. Note that I do not have OSX and can’t provide much support for the platform.
Note: the terms slices and blocks are used interchangeably here
This is a basic example of the high level JS API (note, API not yet finalised so names etc. may change in future):
var par2creator = require('@animetosho/parpar').run(
['file1', 'file2'], // array of input files
1024*1024, // 1MB slice size; if you want a slice count instead, give it as a negative number, e.g. -10 means select a slice size which results in 10 input slices
{ // options; all these are optional
outputBase: 'my_recovery_set',
recoverySlices: { // can also be an array of such objects, of which the sum all these are used
unit: 'slices', // slices/count, ratio, bytes, largest_files, smallest_files, power or ilog
value: ,
scale: 1 // multiply the number of blocks by this amount
},
// the following are the default values for other options
//outputBase: '', // output filename without extension
minSliceSize: null, // default(null) => use sliceSize; give negative number to indicate slice count
maxSliceSize: null,
sliceSizeMultiple: 4,
//recoverySlices: 0,
minRecoverySlices: null, // default = recoverySlices
maxRecoverySlices: {
unit: 'slices',
value: 65537
},
recoveryOffset: 0,
memoryLimit: 256*1048576,
minChunkSize: 128*1024, // 0 to disable chunking
noChunkFirstPass: false,
processBatchSize: null, // default = max(numthreads * 16, ceil(4M/chunkSize))
processBufferSize: null, // default = processBatchSize
comments: [], // array of strings
unicode: null, // null => auto, false => never, true => always generate unicode packets
outputOverwrite: false,
outputIndex: true,
outputSizeScheme: 'pow2', // equal, uniform or pow2
outputFirstFileSlices: null, // null => default, otherwise pass in same format as outputFileMaxSlices
outputFirstFileSlicesRounding: 'round', // round, floor or ceil
outputFileMaxSlices: {
unit: 'slices',
value: 65536
},
outputFileMaxSlicesRounding: 'round', // round, floor or ceil
criticalRedundancyScheme: 'pow2', // none or pow2
outputAltNamingScheme: true,
displayNameFormat: 'common', // basename, keep, common or path
displayNameBase: '.', // base path, only used if displayNameFormat is 'path'
seqReadSize: 4*1048576
},
function(err) {
console.log(err || 'Process finished');
}
);
par2creator.on('info', function(par) {
console.log('Creating PAR2 archive with ' + par.opts.recoverySlices*par.opts.sliceSize + ' byte(s) of recovery data from ' + par.totalSize + ' input bytes');
});
par2creator.on('processing_file', function(par, file) {
console.log('Processing input file ' + file.name);
});
par2creator.on('processing_slice', function(par, file, sliceNum) {
console.log('Processing slice #' + sliceNum + ' of ' + par.inputSlices + ' from ' + file.name);
});
par2creator.on('pass_complete', function(par, passNum, passChunkNum) {
console.log('Completed read pass ' + passNum + ' of ' + par.passes + ' pass(es)');
});
par2creator.on('files_written', function(par, passNum, passChunkNum) {
console.log('Written data for read pass ' + passNum);
});
Returns a normal node Buffer of specified size. The only difference between this
and using new Buffer is that this function guarantees the Buffer to be aligned
to memory boundaries needed for processing. Use of this function is strictly
optional, as ParPar will copy passed input into an AlignedBuffer if the supplied
buffer is not aligned. So this function is only useful if you wish to avoid
unnecessary memory copying.
Remaining API documentation to be done
Examples for the low level JS API can be found in the examples folder.
Currently only some very basic test scripts are included, which can be found in the aptly named test folder.
md5.js tests the internal MD5 implementation against the reference OpenSSL implementation in Node.
par-compare.js tests PAR2 generation by comparing output from ParPar against
that of par2cmdline. As such, par2cmdline needs to be installed for tests to be
run. Note that tests will cover extreme cases, including those using large
amounts of memory, generating large amounts of recovery data and so on. As such,
you will likely need a machine with large amounts of RAM available (preferrably
at least 8GB) and reasonable amount of free disk space available (20GB or more
recommended) to successfully run all tests.
The test will write several files to a temporary location (sourced from TEMP
or TMP environment variables, or the current working directory if none set)
and will likely take a while to complete.
Compiling ParPar into a single binary can be done via nexe 1.x. The process is basically the same as building Nyuu’s binary, so see those instructions for details.
For a list of command-line PAR2 tools, see here.
For a nodejs module, there’s node-par2 which is not an implementation of PAR2, rather a wrapper around par2cmdline.
For a C++ library implementation, there’s libpar2, which I believe is based off par2cmdline.
This code is Public Domain or CC0 (or equivalent) if PD isn’t recognised.
Multi-buffer MD5 implementation is based off implementation from OpenSSL.