ronomon/reed-solomon

Fast, reliable Reed-Solomon erasure coding as a native addon for Node.js.

reed-solomon

Fast, reliable Reed-Solomon erasure coding as a native addon for Node.js, licensed under the MIT License.

For an introduction to erasure coding, see this post by Brian Beach on the Backblaze blog.

• Installation
• Performance
• Usage
• Tests
• Benchmark

Installation

npm install @ronomon/reed-solomon

Performance

The native addon executes asynchronously in Node's threadpool without blocking the event loop:

       CPU | Intel(R) Xeon(R) CPU E3-1230 V2 @ 3.30GHz
     CORES | 8
   THREADS | 1

------------------------------------------------------------------
      DATA |     PARITY | SHARD SIZE |    LATENCY |     THROUGHPUT
------------------------------------------------------------------
         1 |          1 |       4096 |    0.202ms |     20.29 MB/s
         1 |          1 |      65536 |    0.038ms |   1720.57 MB/s
         1 |          1 |     262144 |    0.048ms |   5435.80 MB/s
------------------------------------------------------------------
         1 |          2 |       4096 |    0.020ms |    199.95 MB/s
         1 |          2 |      65536 |    0.025ms |   2606.39 MB/s
         1 |          2 |     262144 |    0.081ms |   3249.66 MB/s
------------------------------------------------------------------
         1 |          3 |       4096 |    0.023ms |    177.43 MB/s
         1 |          3 |      65536 |    0.033ms |   2004.03 MB/s
         1 |          3 |     262144 |    0.108ms |   2428.02 MB/s
------------------------------------------------------------------
         1 |          4 |       4096 |    0.027ms |    149.38 MB/s
         1 |          4 |      65536 |    0.041ms |   1611.52 MB/s
         1 |          4 |     262144 |    0.134ms |   1952.67 MB/s
------------------------------------------------------------------
         2 |          1 |       4096 |    0.041ms |    197.48 MB/s
         2 |          1 |      65536 |    0.057ms |   2285.90 MB/s
         2 |          1 |     262144 |    0.114ms |   4611.48 MB/s
------------------------------------------------------------------
         2 |          2 |       4096 |    0.049ms |    166.09 MB/s
         2 |          2 |      65536 |    0.075ms |   1736.75 MB/s
         2 |          2 |     262144 |    0.203ms |   2579.89 MB/s
------------------------------------------------------------------
         2 |          3 |       4096 |    0.064ms |    128.74 MB/s
         2 |          3 |      65536 |    0.093ms |   1414.32 MB/s
         2 |          3 |     262144 |    0.316ms |   1659.31 MB/s
------------------------------------------------------------------
         2 |          4 |       4096 |    0.060ms |    135.47 MB/s
         2 |          4 |      65536 |    0.111ms |   1182.68 MB/s
         2 |          4 |     262144 |    0.430ms |   1220.38 MB/s
------------------------------------------------------------------
         3 |          1 |       4096 |    0.065ms |    189.66 MB/s
         3 |          1 |      65536 |    0.076ms |   2602.82 MB/s
         3 |          1 |     262144 |    0.182ms |   4329.66 MB/s
------------------------------------------------------------------
         3 |          2 |       4096 |    0.059ms |    209.24 MB/s
         3 |          2 |      65536 |    0.095ms |   2073.39 MB/s
         3 |          2 |     262144 |    0.322ms |   2441.14 MB/s
------------------------------------------------------------------
         3 |          3 |       4096 |    0.060ms |    204.08 MB/s
         3 |          3 |      65536 |    0.119ms |   1649.52 MB/s
         3 |          3 |     262144 |    0.473ms |   1663.10 MB/s
------------------------------------------------------------------
         3 |          4 |       4096 |    0.076ms |    162.42 MB/s
         3 |          4 |      65536 |    0.227ms |    867.70 MB/s
         3 |          4 |     262144 |    0.618ms |   1273.22 MB/s
------------------------------------------------------------------
         4 |          1 |       4096 |    0.060ms |    273.79 MB/s
         4 |          1 |      65536 |    0.087ms |   3023.48 MB/s
         4 |          1 |     262144 |    0.228ms |   4596.09 MB/s
------------------------------------------------------------------
         4 |          2 |       4096 |    0.056ms |    294.79 MB/s
         4 |          2 |      65536 |    0.111ms |   2362.53 MB/s
         4 |          2 |     262144 |    0.407ms |   2577.41 MB/s
------------------------------------------------------------------
         4 |          3 |       4096 |    0.056ms |    294.13 MB/s
         4 |          3 |      65536 |    0.146ms |   1797.57 MB/s
         4 |          3 |     262144 |    0.623ms |   1681.80 MB/s
------------------------------------------------------------------
         4 |          4 |       4096 |    0.066ms |    248.58 MB/s
         4 |          4 |      65536 |    0.187ms |   1401.34 MB/s
         4 |          4 |     262144 |    0.857ms |   1222.92 MB/s
------------------------------------------------------------------
         5 |          1 |       4096 |    0.067ms |    305.98 MB/s
         5 |          1 |      65536 |    0.150ms |   2177.36 MB/s
         5 |          1 |     262144 |    0.311ms |   4208.79 MB/s
------------------------------------------------------------------
         5 |          2 |       4096 |    0.050ms |    407.33 MB/s
         5 |          2 |      65536 |    0.115ms |   2859.69 MB/s
         5 |          2 |     262144 |    0.500ms |   2621.67 MB/s
------------------------------------------------------------------
         5 |          3 |       4096 |    0.067ms |    304.29 MB/s
         5 |          3 |      65536 |    0.204ms |   1609.13 MB/s
         5 |          3 |     262144 |    0.772ms |   1698.20 MB/s
------------------------------------------------------------------
         5 |          4 |       4096 |    0.074ms |    276.14 MB/s
         5 |          4 |      65536 |    0.257ms |   1274.51 MB/s
         5 |          4 |     262144 |    1.071ms |   1223.68 MB/s
------------------------------------------------------------------
         6 |          1 |       4096 |    0.068ms |    361.53 MB/s
         6 |          1 |      65536 |    0.105ms |   3755.04 MB/s
         6 |          1 |     262144 |    0.354ms |   4439.00 MB/s
------------------------------------------------------------------
         6 |          2 |       4096 |    0.060ms |    409.94 MB/s
         6 |          2 |      65536 |    0.135ms |   2907.23 MB/s
         6 |          2 |     262144 |    0.590ms |   2664.83 MB/s
------------------------------------------------------------------
         6 |          3 |       4096 |    0.064ms |    384.48 MB/s
         6 |          3 |      65536 |    0.237ms |   1662.03 MB/s
         6 |          3 |     262144 |    0.961ms |   1637.34 MB/s
------------------------------------------------------------------
         6 |          4 |       4096 |    0.076ms |    323.20 MB/s
         6 |          4 |      65536 |    0.306ms |   1286.81 MB/s
         6 |          4 |     262144 |    1.269ms |   1239.15 MB/s
------------------------------------------------------------------
         7 |          1 |       4096 |    0.055ms |    518.41 MB/s
         7 |          1 |      65536 |    0.123ms |   3720.08 MB/s
         7 |          1 |     262144 |    0.401ms |   4574.62 MB/s
------------------------------------------------------------------
         7 |          2 |       4096 |    0.055ms |    523.62 MB/s
         7 |          2 |      65536 |    0.172ms |   2665.10 MB/s
         7 |          2 |     262144 |    0.693ms |   2648.54 MB/s
------------------------------------------------------------------
         7 |          3 |       4096 |    0.068ms |    422.02 MB/s
         7 |          3 |      65536 |    0.266ms |   1727.26 MB/s
         7 |          3 |     262144 |    1.100ms |   1668.10 MB/s
------------------------------------------------------------------
         7 |          4 |       4096 |    0.081ms |    352.39 MB/s
         7 |          4 |      65536 |    0.354ms |   1295.14 MB/s
         7 |          4 |     262144 |    1.501ms |   1222.15 MB/s
------------------------------------------------------------------
         8 |          1 |       4096 |    0.046ms |    710.37 MB/s
         8 |          1 |      65536 |    0.104ms |   5024.44 MB/s
         8 |          1 |     262144 |    0.357ms |   5867.80 MB/s
------------------------------------------------------------------
         8 |          2 |       4096 |    0.025ms |   1286.85 MB/s
         8 |          2 |      65536 |    0.130ms |   4019.83 MB/s
         8 |          2 |     262144 |    0.504ms |   4159.09 MB/s
------------------------------------------------------------------
         8 |          3 |       4096 |    0.040ms |    819.81 MB/s
         8 |          3 |      65536 |    0.183ms |   2857.84 MB/s
         8 |          3 |     262144 |    0.683ms |   3072.52 MB/s
------------------------------------------------------------------
         8 |          4 |       4096 |    0.031ms |   1049.90 MB/s
         8 |          4 |      65536 |    0.238ms |   2199.69 MB/s
         8 |          4 |     262144 |    0.983ms |   2133.64 MB/s
------------------------------------------------------------------
         9 |          1 |       4096 |    0.035ms |   1045.72 MB/s
         9 |          1 |      65536 |    0.085ms |   6926.25 MB/s
         9 |          1 |     262144 |    0.370ms |   6376.90 MB/s
------------------------------------------------------------------
         9 |          2 |       4096 |    0.038ms |    982.72 MB/s
         9 |          2 |      65536 |    0.147ms |   4005.27 MB/s
         9 |          2 |     262144 |    0.577ms |   4088.25 MB/s
------------------------------------------------------------------
         9 |          3 |       4096 |    0.041ms |    893.76 MB/s
         9 |          3 |      65536 |    0.224ms |   2629.15 MB/s
         9 |          3 |     262144 |    0.869ms |   2715.82 MB/s
------------------------------------------------------------------
         9 |          4 |       4096 |    0.043ms |    866.49 MB/s
         9 |          4 |      65536 |    0.331ms |   1779.40 MB/s
         9 |          4 |     262144 |    1.281ms |   1842.45 MB/s
------------------------------------------------------------------
        10 |          1 |       4096 |    0.027ms |   1508.91 MB/s
        10 |          1 |      65536 |    0.097ms |   6757.32 MB/s
        10 |          1 |     262144 |    0.421ms |   6233.25 MB/s
------------------------------------------------------------------
        10 |          2 |       4096 |    0.033ms |   1250.72 MB/s
        10 |          2 |      65536 |    0.167ms |   3925.31 MB/s
        10 |          2 |     262144 |    0.654ms |   4011.25 MB/s
------------------------------------------------------------------
        10 |          3 |       4096 |    0.040ms |   1025.30 MB/s
        10 |          3 |      65536 |    0.242ms |   2703.63 MB/s
        10 |          3 |     262144 |    1.047ms |   2504.04 MB/s
------------------------------------------------------------------
        10 |          4 |       4096 |    0.050ms |    824.13 MB/s
        10 |          4 |      65536 |    0.358ms |   1829.99 MB/s
        10 |          4 |     262144 |    1.393ms |   1881.64 MB/s
------------------------------------------------------------------
        11 |          1 |       4096 |    0.029ms |   1565.69 MB/s
        11 |          1 |      65536 |    0.107ms |   6725.60 MB/s
        11 |          1 |     262144 |    0.433ms |   6661.48 MB/s
------------------------------------------------------------------
        11 |          2 |       4096 |    0.041ms |   1108.18 MB/s
        11 |          2 |      65536 |    0.194ms |   3721.06 MB/s
        11 |          2 |     262144 |    0.685ms |   4207.69 MB/s
------------------------------------------------------------------
        11 |          3 |       4096 |    0.035ms |   1280.41 MB/s
        11 |          3 |      65536 |    0.265ms |   2718.35 MB/s
        11 |          3 |     262144 |    1.144ms |   2520.31 MB/s
------------------------------------------------------------------
        11 |          4 |       4096 |    0.051ms |    880.45 MB/s
        11 |          4 |      65536 |    0.417ms |   1727.85 MB/s
        11 |          4 |     262144 |    1.600ms |   1802.67 MB/s
------------------------------------------------------------------
        12 |          1 |       4096 |    0.042ms |   1168.18 MB/s
        12 |          1 |      65536 |    0.121ms |   6489.28 MB/s
        12 |          1 |     262144 |    0.442ms |   7124.52 MB/s
------------------------------------------------------------------
        12 |          2 |       4096 |    0.029ms |   1696.64 MB/s
        12 |          2 |      65536 |    0.188ms |   4185.55 MB/s
        12 |          2 |     262144 |    0.832ms |   3782.82 MB/s
------------------------------------------------------------------
        12 |          3 |       4096 |    0.059ms |    839.80 MB/s
        12 |          3 |      65536 |    0.323ms |   2434.45 MB/s
        12 |          3 |     262144 |    1.314ms |   2393.83 MB/s
------------------------------------------------------------------
        12 |          4 |       4096 |    0.066ms |    740.71 MB/s
        12 |          4 |      65536 |    0.445ms |   1767.18 MB/s
        12 |          4 |     262144 |    1.739ms |   1808.54 MB/s
------------------------------------------------------------------
        13 |          1 |       4096 |    0.029ms |   1832.60 MB/s
        13 |          1 |      65536 |    0.117ms |   7284.64 MB/s
        13 |          1 |     262144 |    0.519ms |   6566.15 MB/s
------------------------------------------------------------------
        13 |          2 |       4096 |    0.035ms |   1523.66 MB/s
        13 |          2 |      65536 |    0.242ms |   3514.81 MB/s
        13 |          2 |     262144 |    0.964ms |   3534.83 MB/s
------------------------------------------------------------------
        13 |          3 |       4096 |    0.045ms |   1187.89 MB/s
        13 |          3 |      65536 |    0.354ms |   2406.95 MB/s
        13 |          3 |     262144 |    1.457ms |   2339.49 MB/s
------------------------------------------------------------------
        13 |          4 |       4096 |    0.082ms |    648.33 MB/s
        13 |          4 |      65536 |    0.642ms |   1327.69 MB/s
        13 |          4 |     262144 |    2.542ms |   1340.53 MB/s
------------------------------------------------------------------
        14 |          1 |       4096 |    0.028ms |   2030.67 MB/s
        14 |          1 |      65536 |    0.122ms |   7500.05 MB/s
        14 |          1 |     262144 |    0.564ms |   6504.95 MB/s
------------------------------------------------------------------
        14 |          2 |       4096 |    0.039ms |   1471.78 MB/s
        14 |          2 |      65536 |    0.286ms |   3204.86 MB/s
        14 |          2 |     262144 |    1.078ms |   3404.64 MB/s
------------------------------------------------------------------
        14 |          3 |       4096 |    0.065ms |    888.39 MB/s
        14 |          3 |      65536 |    0.519ms |   1766.39 MB/s
        14 |          3 |     262144 |    2.019ms |   1817.82 MB/s
------------------------------------------------------------------
        14 |          4 |       4096 |    0.090ms |    634.96 MB/s
        14 |          4 |      65536 |    0.713ms |   1286.64 MB/s
        14 |          4 |     262144 |    2.817ms |   1302.66 MB/s
------------------------------------------------------------------
        15 |          1 |       4096 |    0.032ms |   1907.47 MB/s
        15 |          1 |      65536 |    0.140ms |   7040.96 MB/s
        15 |          1 |     262144 |    0.618ms |   6365.28 MB/s
------------------------------------------------------------------
        15 |          2 |       4096 |    0.047ms |   1315.35 MB/s
        15 |          2 |      65536 |    0.304ms |   3234.42 MB/s
        15 |          2 |     262144 |    1.130ms |   3481.12 MB/s
------------------------------------------------------------------
        15 |          3 |       4096 |    0.085ms |    726.10 MB/s
        15 |          3 |      65536 |    0.593ms |   1657.45 MB/s
        15 |          3 |     262144 |    2.148ms |   1830.25 MB/s
------------------------------------------------------------------
        15 |          4 |       4096 |    0.120ms |    513.61 MB/s
        15 |          4 |      65536 |    0.738ms |   1332.41 MB/s
        15 |          4 |     262144 |    3.033ms |   1296.38 MB/s
------------------------------------------------------------------
        16 |          1 |       4096 |    0.044ms |   1488.75 MB/s
        16 |          1 |      65536 |    0.134ms |   7848.64 MB/s
        16 |          1 |     262144 |    0.592ms |   7081.85 MB/s
------------------------------------------------------------------
        16 |          2 |       4096 |    0.043ms |   1512.59 MB/s
        16 |          2 |      65536 |    0.295ms |   3558.64 MB/s
        16 |          2 |     262144 |    1.184ms |   3542.97 MB/s
------------------------------------------------------------------
        16 |          3 |       4096 |    0.090ms |    732.23 MB/s
        16 |          3 |      65536 |    0.634ms |   1653.17 MB/s
        16 |          3 |     262144 |    2.428ms |   1727.20 MB/s
------------------------------------------------------------------
        16 |          4 |       4096 |    0.115ms |    571.62 MB/s
        16 |          4 |      65536 |    0.852ms |   1230.77 MB/s
        16 |          4 |     262144 |    3.396ms |   1234.95 MB/s
------------------------------------------------------------------
        17 |          1 |       4096 |    0.033ms |   2102.59 MB/s
        17 |          1 |      65536 |    0.172ms |   6482.07 MB/s
        17 |          1 |     262144 |    0.587ms |   7590.47 MB/s
------------------------------------------------------------------
        17 |          2 |       4096 |    0.040ms |   1741.43 MB/s
        17 |          2 |      65536 |    0.316ms |   3528.31 MB/s
        17 |          2 |     262144 |    1.334ms |   3341.86 MB/s
------------------------------------------------------------------
        17 |          3 |       4096 |    0.081ms |    854.85 MB/s
        17 |          3 |      65536 |    0.642ms |   1735.37 MB/s
        17 |          3 |     262144 |    2.657ms |   1677.29 MB/s
------------------------------------------------------------------
        17 |          4 |       4096 |    0.118ms |    590.97 MB/s
        17 |          4 |      65536 |    0.881ms |   1264.46 MB/s
        17 |          4 |     262144 |    3.677ms |   1211.94 MB/s
------------------------------------------------------------------
        18 |          1 |       4096 |    0.045ms |   1621.06 MB/s
        18 |          1 |      65536 |    0.161ms |   7337.85 MB/s
        18 |          1 |     262144 |    0.694ms |   6802.32 MB/s
------------------------------------------------------------------
        18 |          2 |       4096 |    0.061ms |   1217.39 MB/s
        18 |          2 |      65536 |    0.356ms |   3316.56 MB/s
        18 |          2 |     262144 |    1.457ms |   3239.25 MB/s
------------------------------------------------------------------
        18 |          3 |       4096 |    0.083ms |    885.94 MB/s
        18 |          3 |      65536 |    0.689ms |   1711.45 MB/s
        18 |          3 |     262144 |    2.853ms |   1653.91 MB/s
------------------------------------------------------------------
        18 |          4 |       4096 |    0.110ms |    672.03 MB/s
        18 |          4 |      65536 |    0.905ms |   1303.68 MB/s
        18 |          4 |     262144 |    3.965ms |   1189.92 MB/s
------------------------------------------------------------------
        19 |          1 |       4096 |    0.037ms |   2075.31 MB/s
        19 |          1 |      65536 |    0.217ms |   5737.11 MB/s
        19 |          1 |     262144 |    0.769ms |   6477.97 MB/s
------------------------------------------------------------------
        19 |          2 |       4096 |    0.061ms |   1283.72 MB/s
        19 |          2 |      65536 |    0.375ms |   3324.22 MB/s
        19 |          2 |     262144 |    1.532ms |   3250.41 MB/s
------------------------------------------------------------------
        19 |          3 |       4096 |    0.107ms |    727.70 MB/s
        19 |          3 |      65536 |    0.734ms |   1696.71 MB/s
        19 |          3 |     262144 |    2.993ms |   1664.30 MB/s
------------------------------------------------------------------
        19 |          4 |       4096 |    0.131ms |    595.96 MB/s
        19 |          4 |      65536 |    0.981ms |   1269.12 MB/s
        19 |          4 |     262144 |    4.167ms |   1195.18 MB/s
------------------------------------------------------------------
        20 |          1 |       4096 |    0.052ms |   1560.67 MB/s
        20 |          1 |      65536 |    0.202ms |   6493.22 MB/s
        20 |          1 |     262144 |    0.801ms |   6545.79 MB/s
------------------------------------------------------------------
        20 |          2 |       4096 |    0.054ms |   1506.94 MB/s
        20 |          2 |      65536 |    0.407ms |   3218.66 MB/s
        20 |          2 |     262144 |    1.635ms |   3205.88 MB/s
------------------------------------------------------------------
        20 |          3 |       4096 |    0.105ms |    776.62 MB/s
        20 |          3 |      65536 |    0.758ms |   1728.85 MB/s
        20 |          3 |     262144 |    3.167ms |   1655.57 MB/s
------------------------------------------------------------------
        20 |          4 |       4096 |    0.123ms |    666.05 MB/s
        20 |          4 |      65536 |    1.078ms |   1215.52 MB/s
        20 |          4 |     262144 |    4.415ms |   1187.52 MB/s
------------------------------------------------------------------

Usage

Adjust threadpool size and control concurrency

Please see the crypto-async module for advice on adjusting threadpool size and controlling concurrency.

Encoding Parity Shards

var ReedSolomon = require('@ronomon/reed-solomon');

// Specify the number of data shards (<= ReedSolomon.MAX_K):
var k = 6;

// Specify the number of parity shards (<= ReedSolomon.MAX_M):
var m = 3; // Protect against the loss of any 3 data or parity shards.

// Create an encoding context (can be cached and re-used concurrently):
var context = ReedSolomon.create(k, m);

// Specify the size of each shard in bytes (must be a multiple of 8 bytes):
var shardSize = 65536;

// Allocate the data buffer containing all data shards:
var buffer = Buffer.alloc(shardSize * k);

// Specify the offset into the data buffer at which data shards begin:
// This allows you to include a header.
var bufferOffset = 0;

// Specify the size after this offset of all data shards:
// This allows you to include a footer.
var bufferSize = shardSize * k;

// Allocate the parity buffer containing all parity shards:
var parity = Buffer.alloc(shardSize * m);

// Specify the offset into the parity buffer at which parity shards begin:
// This allows you to include a header.
var parityOffset = 0;

// Specify the size after this offset of all parity shards:
// This allows you to include a footer.
var paritySize = shardSize * m;

// Specify the sources, present in buffer or parity (as bit flags):
// We are encoding parity shards, so we mark all data shards as sources.
var sources = 0;
for (var i = 0; i < k; i++) sources |= (1 << i);

// Specify the targets, missing in buffer or parity, which should be encoded:
// We are encoding parity shards, so we mark all parity shards as targets:
var targets = 0;
for (var i = k; i < k + m; i++) targets |= (1 << i);

// Encode all parity shards:
ReedSolomon.encode(
  context,
  sources,
  targets,
  buffer,
  bufferOffset,
  bufferSize,
  parity,
  parityOffset,
  paritySize,
  function(error) {
    if (error) throw error;
    // Parity shards now contain parity data.
  }
);

Encoding Corrupted Shards

// Corrupt first data shard:
buffer[bufferOffset + (shardSize * 0)] = 255;

// Corrupt first parity shard:
parity[parityOffset + (shardSize * 0)] = 255;

// We still have enough parity to corrupt one more shard.

// Specify the targets, missing in buffer or parity, which should be encoded:
var targets = 0;
targets |= (1 << 0); // Data shard at index 0 needs to be encoded.
targets |= (1 << k); // Parity shard at index 6 (k + 0) needs to be encoded.

// Specify the sources, present in buffer or parity:
// We need at least k sources.
// For this example, we assume that a shard is a source if it is not a target.
// An optimization is available here:
// If a shard is not a source or target, it might not be encoded.
// The shard may be encoded if needed to encode other shards, but otherwise not.
var sources = 0;
for (var i = 0; i < k + m; i++) {
  if (targets & (1 << i)) continue;
  sources |= (1 << i);
}

// Encode the corrupted data and parity shards:
ReedSolomon.encode(
  context,
  sources,
  targets,
  buffer,
  bufferOffset,
  bufferSize,
  parity,
  parityOffset,
  paritySize,
  function(error) {
    if (error) throw error;
    // Data shard at index 0 has been repaired.
    // Parity shard at index 6 has been repaired.
  }
);

Tests

reed-solomon ships with extensive tests, including a long-running fuzz test.

node test.js

Benchmark

node benchmark.js

reed-solomon's Issues

ReedSolomon k+1 broken if parity buffer is not zero'ed

Stumbled upon this one. Reproduced using the attached mocha test (renamed as .txt for github upload)
rononmon.test.txt

Execution gives out:

$ npm test test/rononmon.test.js

> [email protected] test /home/mlubin/dev/ecstream
> mocha --use_strict --check-leaks --no-exit  "test/rononmon.test.js"



  ✓ Test parity initialization - m=1, initValue=0
  1) Test parity initialization - m=1, initValue=255
  ✓ Test parity initialization - m=2, initValue=0
  ✓ Test parity initialization - m=2, initValue=255

  3 passing (13ms)
  1 failing

  1)  Test parity initialization - m=1, initValue=255:

      Uncaught AssertionError: <Buffer db db db db db db db db> === <Buffer 24 24 24 24 24 24 24 24>
      + expected - actual

       [
      -  219
      -  219
      -  219
      -  219
      -  219
      -  219
      -  219
      -  219
      +  36
      +  36
      +  36
      +  36
      +  36
      +  36
      +  36
      +  36
       ]
      
      at ReedSolomon.encode.err (test/rononmon.test.js:38:36)

Handling of m=1 seems very special. Looking at binding.cc code I found the special code path which directly call dot_xor and do not start with a dot_cpy first:

diff --git a/binding.cc b/binding.cc
index b61ecdd..c323b3e 100644
--- a/binding.cc
+++ b/binding.cc
@@ -705,8 +705,16 @@ void encode(
   ) {
     // Optimization for 1 erasure (i < k + 1), encoding only targets:
     uint8_t* target = shards[flags_first(targets)];
+    int copied = 0;
     for (int i = 0; i < k + 1; i++) {
-      if (sources & (1 << i)) dot_xor(shards[i], target, shardSize);
+      if (sources & (1 << i)) {
+        if (!copied) {
+          dot_cpy(shards[i], target, shardSize);
+          copied = 1;
+        } else {
+          dot_xor(shards[i], target, shardSize);
+        }
+      }
     }
     return;
   }

Can be reproduced in your test by forcing random parity buffers in test.js:

diff --git a/test.js b/test.js
index ef462e9..1c1f902 100644
--- a/test.js
+++ b/test.js
@@ -317,7 +317,7 @@ queue.onData = function(args, end) {
   );
   var buffer = cipher.update(Buffer.alloc(bufferOffset + bufferSize));
   Assert(buffer.length === bufferOffset + bufferSize);
-  var parity = Buffer.alloc(parityOffset + paritySize);
+  var parity = Node.crypto.randomBytes(parityOffset + paritySize);
   if (parityOffset) {
     Assert(
       cipher.update(Buffer.alloc(parityOffset)).copy(parity, 0) === parityOffset

The above patch fixes the issue, at least on the simple test I attached and your tests.

Cheers,
Maxime

Detecting silent bit errors?

Hey!

Thank you a lot for your great work! Your implementation is blazingly fast! :)

I have a slightly different use case. I want to detect silent bit errors (resp. damaged shards) and don't know my sources and targets.

Do you see any possibility to add some kind of check() method to your module that returns damaged shards?

Of course we will need at least two parity shards to achieve that. If I a correct with m=2 we can detect if 2 shards are damaged and repair if 1 shard is damaged.

Let me know what you think.

pure JS implementation that can used on the browser ?

Hi,
I am trying to find an implementation that can be used on browser. The goal is to have the erasure coding be performed on the browser and upload the multiple splits to multiple servers.

Any ideas or recommendations ?

Cannot find module './binding.node'

Error: Cannot find module './binding.node'
Require stack:

• E:\nodejs\reed-solomon-master\benchmark.js
  �[90m at Function.Module._resolveFilename (internal/modules/cjs/loader.js:982:15)�[39m
  �[90m at Function.Module._load (internal/modules/cjs/loader.js:864:27)�[39m
  �[90m at Module.require (internal/modules/cjs/loader.js:1044:19)�[39m
  �[90m at require (internal/modules/cjs/helpers.js:77:18)�[39m
  at Object. (E:\nodejs\reed-solomon-master\benchmark.js:8:19)
  �[90m at Module._compile (internal/modules/cjs/loader.js:1158:30)�[39m
  �[90m at Object.Module._extensions..js (internal/modules/cjs/loader.js:1178:10)�[39m
  �[90m at Module.load (internal/modules/cjs/loader.js:1002:32)�[39m
  �[90m at Function.Module._load (internal/modules/cjs/loader.js:901:14)�[39m
  �[90m at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:74:12)�[39m {
  code: �[32m'MODULE_NOT_FOUND'�[39m,
  requireStack: [ �[32m'E:\nodejs\reed-solomon-master\benchmark.js'�[39m ]
  }

I am getting Cannot find module './binding.node' error you have used
var ReedSolomon = require('./binding.node'); code in line no 5 of test.js code

Barebone repo and CI

Do what needs to be done. Have a clean start