// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
 * Ceph distributed storage system
 *
 * Copyright (C) 2014 Red Hat <contact@redhat.com>
 *
 * Author: Loic Dachary <loic@dachary.org>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 */

#include <errno.h>
#include <stdlib.h>

#include "erasure-code/ErasureCode.h"
#include "global/global_context.h"
#include "common/config.h"
#include "gtest/gtest.h"

class ErasureCodeTest : public ErasureCode {
public:
  map<int, bufferlist> encode_chunks_encoded;
  unsigned int k;
  unsigned int m;
  unsigned int chunk_size;

  ErasureCodeTest(unsigned int _k, unsigned int _m, unsigned int _chunk_size) :
    k(_k), m(_m), chunk_size(_chunk_size) {}
  ~ErasureCodeTest() override {}

  int init(ErasureCodeProfile &profile, ostream *ss) override {
    return 0;
  }

  unsigned int get_chunk_count() const override { return k + m; }
  unsigned int get_data_chunk_count() const override { return k; }
  unsigned int get_chunk_size(unsigned int object_size) const override {
    return chunk_size;
  }
  int encode_chunks(const set<int> &want_to_encode,
			    map<int, bufferlist> *encoded) override {
    encode_chunks_encoded = *encoded;
    return 0;
  }
  int create_rule(const string &name,
		  CrushWrapper &crush,
		  ostream *ss) const override { return 0; }
};

/*
 *  If we have a buffer of 5 bytes (X below) and a chunk size of 3
 *  bytes, for k=3, m=1 an additional 7 bytes (P and C below) will
 *  need to be allocated for padding (P) and the 3 coding bytes (C).
 *
 *  X -+ +----------+ +-X
 *  X  | | data   0 | | X
 *  X  | +----------+ | X
 *  X  | +----------+ | X -> +-X
 *  X -+ | data   1 | +-X -> | X
 *  P -+ +----------+        | P
 *  P  | +----------+        | P
 *  P  | | data   2 |        | P
 *  P  | +----------+        | P
 *  C  | +----------+        | C
 *  C  | | coding 3 |        | C
 *  C -+ +----------+        +-C
 *
 *  The data chunks 1 and 2 (data 1 and data 2 above) overflow the
 *  original buffer because it needs padding. A new buffer will
 *  be allocated to contain the chunk that overflows and all other
 *  chunks after it, including the coding chunk(s).
 *
 *  The following test creates a siguation where the buffer provided
 *  for encoding is not memory aligned. After encoding it asserts that:
 *
 *   a) each chunk is SIMD aligned
 *   b) the data 1 chunk content is as expected which implies that its
 *      content has been copied over.
 *
 *  It is possible for a flawed implementation to pas the test because the
 *  underlying allocation function enforces it.
 */
TEST(ErasureCodeTest, encode_memory_align)
{
  int k = 3;
  int m = 1;
  unsigned chunk_size = ErasureCode::SIMD_ALIGN * 7;
  ErasureCodeTest erasure_code(k, m, chunk_size);

  set<int> want_to_encode;
  for (unsigned int i = 0; i < erasure_code.get_chunk_count(); i++)
    want_to_encode.insert(i);
  string data(chunk_size + chunk_size / 2, 'X'); // uses 1.5 chunks out of 3
  // make sure nothing is memory aligned
  bufferptr ptr(buffer::create_aligned(data.length() + 1, ErasureCode::SIMD_ALIGN));
  ptr.copy_in(1, data.length(), data.c_str());
  ptr.set_offset(1);
  ptr.set_length(data.length());
  bufferlist in;
  in.append(ptr);
  map<int, bufferlist> encoded;

  ASSERT_FALSE(in.is_aligned(ErasureCode::SIMD_ALIGN));
  ASSERT_EQ(0, erasure_code.encode(want_to_encode, in, &encoded));
  for (unsigned int i = 0; i < erasure_code.get_chunk_count(); i++)
    ASSERT_TRUE(encoded[i].is_aligned(ErasureCode::SIMD_ALIGN));
  for (unsigned i = 0; i < chunk_size / 2; i++)
    ASSERT_EQ(encoded[1][i], 'X');
  ASSERT_NE(encoded[1][chunk_size / 2], 'X');
}

TEST(ErasureCodeTest, encode_misaligned_non_contiguous)
{
  int k = 3;
  int m = 1;
  unsigned chunk_size = ErasureCode::SIMD_ALIGN * 7;
  ErasureCodeTest erasure_code(k, m, chunk_size);

  set<int> want_to_encode;
  for (unsigned int i = 0; i < erasure_code.get_chunk_count(); i++)
    want_to_encode.insert(i);
  string data(chunk_size, 'X');
  // create a non contiguous bufferlist where the frist and the second
  // bufferptr are not size aligned although they are memory aligned
  bufferlist in;
  {
    bufferptr ptr(buffer::create_aligned(data.length() - 1, ErasureCode::SIMD_ALIGN));
    in.append(ptr);
  }
  {
    bufferptr ptr(buffer::create_aligned(data.length() + 1, ErasureCode::SIMD_ALIGN));
    in.append(ptr);
  }
  map<int, bufferlist> encoded;

  ASSERT_FALSE(in.is_contiguous());
  ASSERT_TRUE(in.front().is_aligned(ErasureCode::SIMD_ALIGN));
  ASSERT_FALSE(in.front().is_n_align_sized(chunk_size));
  ASSERT_TRUE(in.back().is_aligned(ErasureCode::SIMD_ALIGN));
  ASSERT_FALSE(in.back().is_n_align_sized(chunk_size));
  ASSERT_EQ(0, erasure_code.encode(want_to_encode, in, &encoded));
  for (unsigned int i = 0; i < erasure_code.get_chunk_count(); i++) {
    ASSERT_TRUE(encoded[i].is_aligned(ErasureCode::SIMD_ALIGN));
    ASSERT_TRUE(encoded[i].is_n_align_sized(chunk_size));
  }
}

/*
 * Local Variables:
 * compile-command: "cd ../.. ;
 *   make -j4 unittest_erasure_code &&
 *   valgrind --tool=memcheck --leak-check=full \
 *      ./unittest_erasure_code \
 *      --gtest_filter=*.* --log-to-stderr=true"
 * End:
 */