Nevar pievienot vairāk kā 25 tēmas
Tēmai ir jāsākas ar burtu vai ciparu, tā var saturēt domu zīmes ('-') un var būt līdz 35 simboliem gara.
131 rindas
4.0 KiB
131 rindas
4.0 KiB
// 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 "include/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 {
|
|
#ifndef NDEBUG
|
|
const size_t original_size = dst->size();
|
|
#endif
|
|
metaindex_handle_.EncodeTo(dst);
|
|
index_handle_.EncodeTo(dst);
|
|
dst->resize(2 * BlockHandle::kMaxEncodedLength); // Padding
|
|
PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber));
|
|
PutFixed32(dst, static_cast<uint32_t>(kTableMagicNumber >> 32));
|
|
assert(dst->size() == original_size + kEncodedLength);
|
|
}
|
|
|
|
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::InvalidArgument("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,
|
|
Block** block) {
|
|
*block = NULL;
|
|
|
|
// 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 = 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");
|
|
}
|
|
|
|
// 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");
|
|
return s;
|
|
}
|
|
}
|
|
|
|
switch (data[n]) {
|
|
case kNoCompression:
|
|
if (data != buf) {
|
|
// File implementation gave us pointer to some other data.
|
|
// Copy into buf[].
|
|
memcpy(buf, data, n + kBlockTrailerSize);
|
|
}
|
|
|
|
// Ok
|
|
break;
|
|
case kSnappyCompression: {
|
|
std::string decompressed;
|
|
if (!port::Snappy_Uncompress(data, n, &decompressed)) {
|
|
delete[] buf;
|
|
s = Status::Corruption("corrupted compressed block contents");
|
|
return s;
|
|
}
|
|
delete[] buf; // Done with uncompressed data
|
|
buf = new char[decompressed.size()];
|
|
memcpy(buf, decompressed.data(), decompressed.size());
|
|
n = decompressed.size();
|
|
break;
|
|
}
|
|
default:
|
|
delete[] buf;
|
|
return Status::Corruption("bad block type");
|
|
}
|
|
|
|
*block = new Block(buf, n); // Block takes ownership of buf[]
|
|
return Status::OK();
|
|
}
|
|
|
|
}
|