Method _decode

src/test/erasure-code/ErasureCodeExample.h:239–284

  }

  [[deprecated]]
  int _decode(const std::set<int> &want_to_read,
	      const std::map<int, bufferlist> &chunks,
	      std::map<int, bufferlist> *decoded) override {
    //
    // All chunks have the same size
    //
    unsigned chunk_length = (*chunks.begin()).second.length();
    for (std::set<int>::iterator i = want_to_read.begin();
         i != want_to_read.end();
         ++i) {
      if (chunks.find(*i) != chunks.end()) {
	//
	// If the chunk is available, just copy the bufferptr pointer
	// to the decoded argument.
	//
        (*decoded)[*i] = chunks.find(*i)->second;
      } else if(chunks.size() != 2) {
	//
	// If a chunk is missing and there are not enough chunks
	// to recover, abort.
	//
	return -ERANGE;
      } else {
	//
	// No matter what the missing chunk is, XOR of the other
	// two recovers it.
	//
        std::map<int, bufferlist>::const_iterator k = chunks.begin();
        const char *a = k->second.front().c_str();
        ++k;
        const char *b = k->second.front().c_str();
        bufferptr chunk(chunk_length);
	char *c = chunk.c_str();
        for (unsigned j = 0; j < chunk_length; j++) {
          c[j] = a[j] ^ b[j];
        }

	bufferlist tmp;
	tmp.append(chunk);
	tmp.claim_append((*decoded)[*i]);
	(*decoded)[*i].swap(tmp);
      }
    }
    return 0;
  }


  int _decode(const shard_id_set &want_to_read,