Method encode_decode

src/test/erasure-code/TestErasureCodeIsa.cc:50–179

}

void IsaErasureCodeTest::encode_decode(unsigned object_size)
{
  ErasureCodeIsaDefault Isa(tcache, "reed_sol_van");

  ErasureCodeProfile profile;
  profile["k"] = "2";
  profile["m"] = "2";
  Isa.init(profile, &cerr);

  string payload(object_size, 'X');
  bufferlist in;
  // may be multiple bufferptr if object_size is larger than CEPH_PAGE_SIZE
  in.append(payload.c_str(), payload.length());
  int want_to_encode[] = {0, 1, 2, 3};
  shard_id_map<bufferlist> encoded(Isa.get_chunk_count());
  EXPECT_EQ(0, Isa.encode(shard_id_set(want_to_encode, want_to_encode + 4),
                          in,
                          &encoded));
  EXPECT_EQ(4u, encoded.size());
  unsigned chunk_size = encoded[shard_id_t(0)].length();
  EXPECT_EQ(chunk_size, Isa.get_chunk_size(object_size));
  compare_chunks(in, encoded);

  // all chunks are available
  {
    int want_to_decode[] = {0, 1};
    shard_id_map<bufferlist> decoded(Isa.get_chunk_count());
    EXPECT_EQ(0, Isa._decode(shard_id_set(want_to_decode, want_to_decode + 2),
			     encoded,
			     &decoded));
    EXPECT_EQ(2u, decoded.size());
    EXPECT_EQ(chunk_size, decoded[shard_id_t(0)].length());
    compare_chunks(in, decoded);
  }

  // one data chunk is missing
  {
    shard_id_map<bufferlist> degraded = encoded;

    string enc1(encoded[shard_id_t(1)].c_str(), chunk_size);

    degraded.erase(shard_id_t(1));
    EXPECT_EQ(3u, degraded.size());
    int want_to_decode[] = {1};
    shard_id_map<bufferlist> decoded(Isa.get_chunk_count());
    EXPECT_EQ(0, Isa._decode(shard_id_set(want_to_decode, want_to_decode + 1),
			     degraded,
			     &decoded));
    // always decode all, regardless of want_to_decode
    EXPECT_EQ(4u, decoded.size());
    EXPECT_EQ(chunk_size, decoded[shard_id_t(1)].length());
    EXPECT_EQ(0, memcmp(decoded[shard_id_t(1)].c_str(), enc1.c_str(), chunk_size));
  }

  // non-xor coding chunk is missing
  {
    shard_id_map<bufferlist> degraded = encoded;