Metadata-Version: 2.1
Name: pyjerasure
Version: 1.0.1
Summary: Python Wrapper for Jerasure
Home-page: https://github.com/ktnrg45/pyjerasure
Author: ktnrg45
Author-email: ktnrg45dev@gmail.com
License: Apache
Description: # pyjerasure
        Python Wrapper library for libjerasure
        
        Only basic encoding/decoding methods are implemented.
        
        ## Usage
        
        In this example we have blocks of data that we would like to protect against data loss. 
        
        ```
        data = [
          b"hello",
          b"world",
          b"data-123",
          b"data-0123456789A",
        ]
        ```
        First we import the library and setup our matrix.
        
        There are multiple matrix types available which can be shown with `Matrix.TYPES`
        ```
        import pyjerasure
        
        matrix_type = "rs_r6"
        k = 4  # Number of data blocks
        m = 2  # Number of coding blocks. This is also the maximum number of blocks that can be lost.
        w = 8  # Word Size
        
        matrix = pyjerasure.Matrix(matrix_type, k, m, w)
        ```
        Next we encode our data using the matrix.
        This adds redundant coding blocks to our data.
        
        ```
        coded_data = pyjerasure.encode_from_blocks(matrix, data)
        print(coded_data)
        
        #  Outputs:
        #
        #  [b'hello\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'world\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'data-123\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'data-0123456789A',
        #   b'\x1f\n\x1e\x00\x0b\x01\x03\x013456789A',
        #   b'\x0c\r\xc2\x02fY]A\x85\xbd\xb5\xad\xa5\xdd\xd52']
        #
        ```
        Notice how some of our data has been padded with zeroed bytes.
        This is necessary for encoding our data.
        The `*_from_blocks` method automatically pads data to the correct length.
        
        
        Now we're going to simulate a loss of data by deleting 'm' blocks.
        
        ```
        missing = [1, 3]
        for i in missing:
          coded_data[i] = b""
        print(coded_data)
        
        #  Outputs:
        #
        #  [b'hello\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'',
        #   b'data-123\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'',
        #   b'\x1f\n\x1e\x00\x0b\x01\x03\x013456789A',
        #   b'\x0c\r\xc2\x02fY]A\x85\xbd\xb5\xad\xa5\xdd\xd52']
        #
        ```
        
        Recovering the data can be done if we know the indexes of the missing blocks.
        
        ```
        restored = pyjerasure.decode_from_blocks(matrix, coded_data, missing)
        print(restored)
        
        #  Outputs:
        #
        #  [b'hello\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'world\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'data-123\x00\x00\x00\x00\x00\x00\x00\x00',
        #   b'data-0123456789A',
        #   b'\x1f\n\x1e\x00\x0b\x01\x03\x013456789A',
        #   b'\x0c\r\xc2\x02fY]A\x85\xbd\xb5\xad\xa5\xdd\xd52']
        #
        ```
        Blocks can be encoded and decoded as a byte string using the `*_from_bytes` methods.
        Each block needs to be padded in respect to the longest block. The `align_size` method returns the appropriate size for each block.
        The `Matrix.align_block` method pads each block.
        
        ```
        matrix_type = "cauchy"
        matrix = pyjerasure.Matrix(matrix_type, k, m, w)
        size = max([len(block) for block in data])
        padded = [matrix.align_block(block, size) for block in data]
        padded_data = b"".join(padded)
        encoded = pyjerasure.encode_from_bytes(matrix, padded_data, size)
        print(encoded)
        
        #  Outputs:
        #
        #  b'hello\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
        #    world\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
        #    data-123\x00\x00\x00\x00\x00\x00\x00\x00
        #    data-0123456789A
        #    M\x8a\xea\x01+\xb0\xdem\x0f]\xfa\x0e\xa9\xaa\r\x15
        #    2\x89\xef\x01RP\xe3\x8d\xc5\rJ\x83\xc4\x0eIW'
        #
        
        block_size = len(encoded) // (matrix.k + matrix.m)
        erased = bytearray(encoded)
        erased[:block_size * 2] = bytes(block_size * 2) # Erase first two blocks.
        erased = bytes(erased)
        print(erased)
        
        #  Outputs:
        #
        #  b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
        #    \x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 
        #    data-123\x00\x00\x00\x00\x00\x00\x00\x00
        #    data-0123456789A
        #    M\x8a\xea\x01+\xb0\xdem\x0f]\xfa\x0e\xa9\xaa\r\x15
        #    2\x89\xef\x01RP\xe3\x8d\xc5\rJ\x83\xc4\x0eIW'
        #
        
        erasures = [0, 1]
        restored = pyjerasure.decode_from_bytes(matrix, erased, erasures, size)
        print(restored)
        
        #  Outputs:
        #
        #  b'hello\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
        #    world\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00
        #    data-123\x00\x00\x00\x00\x00\x00\x00\x00
        #    data-0123456789A
        #    M\x8a\xea\x01+\xb0\xdem\x0f]\xfa\x0e\xa9\xaa\r\x15
        #    2\x89\xef\x01RP\xe3\x8d\xc5\rJ\x83\xc4\x0eIW'
        #
        
        ```
        
        # Installing
        
        ## Using pip
        ```
        pip install pyjerasure
        ```
        
        ## From Source
        Installing from source requires `libjerasure-dev` to be installed.
        In addition, `cython` may need to be installed as well.
        
        ```
        pip install cython
        python setup.py install build_ext
        ```
        
        
        # Original License
        
        Copyright (c) 2013, James S. Plank and Kevin Greenan
        All rights reserved.
        
        Jerasure - A C/C++ Library for a Variety of Reed-Solomon and RAID-6 Erasure Coding Techniques
        
        Revision 2.0: Galois Field backend now links to GF-Complete
        
        Redistribution and use in source and binary forms, with or without
        modification, are permitted provided that the following conditions
        are met:
        
         - Redistributions of source code must retain the above copyright
           notice, this list of conditions and the following disclaimer.
        
         - Redistributions in binary form must reproduce the above copyright
           notice, this list of conditions and the following disclaimer in
           the documentation and/or other materials provided with the
           distribution.
        
         - Neither the name of the University of Tennessee nor the names of its
           contributors may be used to endorse or promote products derived
           from this software without specific prior written permission.
        
        THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
        "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
        LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
        A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
        HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
        INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
        BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
        OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
        AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
        WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
        POSSIBILITY OF SUCH DAMAGE.
        
Keywords: jerasure erasure erasures
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Natural Language :: English
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python :: 3.8
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Requires-Python: >=3.6
Description-Content-Type: text/markdown
