git / moonbite-core / src/leveldb/table/format.cc · raw

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.// Use of this source code is governed by a BSD-style license that can be// found in the LICENSE file. See the AUTHORS file for names of contributors.#include "table/format.h"#include "leveldb/env.h"#include "port/port.h"#include "table/block.h"#include "util/coding.h"#include "util/crc32c.h"namespace leveldb {void BlockHandle::EncodeTo(std::string* dst) const {  // Sanity check that all fields have been set  assert(offset_ != ~static_cast<uint64_t>(0));  assert(size_ != ~static_cast<uint64_t>(0));  PutVarint64(dst, offset_);  PutVarint64(dst, size_);}Status BlockHandle::DecodeFrom(Slice* input) {  if (GetVarint64(input, &offset_) && GetVarint64(input, &size_)) {    return Status::OK();  } else {    return Status::Corruption("bad block handle");  }}void Footer::EncodeTo(std::string* dst) const {  const size_t original_size = dst->size();  metaindex_handle_.EncodeTo(dst);  index_handle_.EncodeTo(dst);  dst->resize(2 * BlockHandle::kMaxEncodedLength);  // Padding  PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber & 0xffffffffu));  PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber >> 32));  assert(dst->size() == original_size + kEncodedLength);  (void)original_size;  // Disable unused variable warning.}Status Footer::DecodeFrom(Slice* input) {  const char* magic_ptr = input->data() + kEncodedLength - 8;  const uint32_t magic_lo = DecodeFixed32(magic_ptr);  const uint32_t magic_hi = DecodeFixed32(magic_ptr + 4);  const uint64_t magic = ((static_cast<uint64_t>(magic_hi) << 32) |                          (static_cast<uint64_t>(magic_lo)));  if (magic != kTableMagicNumber) {    return Status::Corruption("not an sstable (bad magic number)");  }  Status result = metaindex_handle_.DecodeFrom(input);  if (result.ok()) {    result = index_handle_.DecodeFrom(input);  }  if (result.ok()) {    // We skip over any leftover data (just padding for now) in "input"    const char* end = magic_ptr + 8;    *input = Slice(end, input->data() + input->size() - end);  }  return result;}Status ReadBlock(RandomAccessFile* file, const ReadOptions& options,                 const BlockHandle& handle, BlockContents* result) {  result->data = Slice();  result->cachable = false;  result->heap_allocated = false;  // Read the block contents as well as the type/crc footer.  // See table_builder.cc for the code that built this structure.  size_t n = static_cast<size_t>(handle.size());  char* buf = new char[n + kBlockTrailerSize];  Slice contents;  Status s = file->Read(handle.offset(), n + kBlockTrailerSize, &contents, buf);  if (!s.ok()) {    delete[] buf;    return s;  }  if (contents.size() != n + kBlockTrailerSize) {    delete[] buf;    return Status::Corruption("truncated block read", file->GetName());  }  // Check the crc of the type and the block contents  const char* data = contents.data();  // Pointer to where Read put the data  if (options.verify_checksums) {    const uint32_t crc = crc32c::Unmask(DecodeFixed32(data + n + 1));    const uint32_t actual = crc32c::Value(data, n + 1);    if (actual != crc) {      delete[] buf;      s = Status::Corruption("block checksum mismatch", file->GetName());      return s;    }  }  switch (data[n]) {    case kNoCompression:      if (data != buf) {        // File implementation gave us pointer to some other data.        // Use it directly under the assumption that it will be live        // while the file is open.        delete[] buf;        result->data = Slice(data, n);        result->heap_allocated = false;        result->cachable = false;  // Do not double-cache      } else {        result->data = Slice(buf, n);        result->heap_allocated = true;        result->cachable = true;      }      // Ok      break;    case kSnappyCompression: {      size_t ulength = 0;      if (!port::Snappy_GetUncompressedLength(data, n, &ulength)) {        delete[] buf;        return Status::Corruption("corrupted compressed block contents", file->GetName());      }      char* ubuf = new char[ulength];      if (!port::Snappy_Uncompress(data, n, ubuf)) {        delete[] buf;        delete[] ubuf;        return Status::Corruption("corrupted compressed block contents", file->GetName());      }      delete[] buf;      result->data = Slice(ubuf, ulength);      result->heap_allocated = true;      result->cachable = true;      break;    }    default:      delete[] buf;      return Status::Corruption("bad block type", file->GetName());  }  return Status::OK();}}  // namespace leveldb