ronomon / reed-solomon Goto Github PK

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.

Do what needs to be done. Have a clean start

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

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 ?

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