format.cc
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
//
// 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 <string>
#include <inttypes.h>
#include "rocksdb/env.h"
#include "table/block.h"
#include "table/block_based_table_reader.h"
#include "table/persistent_cache_helper.h"
#include "util/coding.h"
#include "util/compression.h"
#include "util/crc32c.h"
#include "util/file_reader_writer.h"
#include "util/perf_context_imp.h"
#include "util/string_util.h"
#include "util/xxhash.h"
#include "util/statistics.h"
#include "util/stop_watch.h"
namespace rocksdb {
extern const uint64_t kLegacyBlockBasedTableMagicNumber;
extern const uint64_t kBlockBasedTableMagicNumber;
#ifndef ROCKSDB_LITE
extern const uint64_t kLegacyPlainTableMagicNumber;
extern const uint64_t kPlainTableMagicNumber;
#else
// ROCKSDB_LITE doesn't have plain table
const uint64_t kLegacyPlainTableMagicNumber = 0;
const uint64_t kPlainTableMagicNumber = 0;
#endif
const uint32_t DefaultStackBufferSize = 5000;
bool ShouldReportDetailedTime(Env* env, Statistics* stats) {
return env != nullptr && stats != nullptr &&
stats->stats_level_ > kExceptDetailedTimers;
}
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));
PutVarint64Varint64(dst, offset_, size_);
}
Status BlockHandle::DecodeFrom(Slice* input) {
if (GetVarint64(input, &offset_) &&
GetVarint64(input, &size_)) {
return Status::OK();
} else {
// reset in case failure after partially decoding
offset_ = 0;
size_ = 0;
return Status::Corruption("bad block handle");
}
}
// Return a string that contains the copy of handle.
std::string BlockHandle::ToString(bool hex) const {
std::string handle_str;
EncodeTo(&handle_str);
if (hex) {
return Slice(handle_str).ToString(true);
} else {
return handle_str;
}
}
const BlockHandle BlockHandle::kNullBlockHandle(0, 0);
namespace {
inline bool IsLegacyFooterFormat(uint64_t magic_number) {
return magic_number == kLegacyBlockBasedTableMagicNumber ||
magic_number == kLegacyPlainTableMagicNumber;
}
inline uint64_t UpconvertLegacyFooterFormat(uint64_t magic_number) {
if (magic_number == kLegacyBlockBasedTableMagicNumber) {
return kBlockBasedTableMagicNumber;
}
if (magic_number == kLegacyPlainTableMagicNumber) {
return kPlainTableMagicNumber;
}
assert(false);
return 0;
}
} // namespace
// legacy footer format:
// metaindex handle (varint64 offset, varint64 size)
// index handle (varint64 offset, varint64 size)
// <padding> to make the total size 2 * BlockHandle::kMaxEncodedLength
// table_magic_number (8 bytes)
// new footer format:
// checksum (char, 1 byte)
// metaindex handle (varint64 offset, varint64 size)
// index handle (varint64 offset, varint64 size)
// <padding> to make the total size 2 * BlockHandle::kMaxEncodedLength + 1
// footer version (4 bytes)
// table_magic_number (8 bytes)
void Footer::EncodeTo(std::string* dst) const {
assert(HasInitializedTableMagicNumber());
if (IsLegacyFooterFormat(table_magic_number())) {
// has to be default checksum with legacy footer
assert(checksum_ == kCRC32c);
const size_t original_size = dst->size();
metaindex_handle_.EncodeTo(dst);
index_handle_.EncodeTo(dst);
dst->resize(original_size + 2 * BlockHandle::kMaxEncodedLength); // Padding
PutFixed32(dst, static_cast<uint32_t>(table_magic_number() & 0xffffffffu));
PutFixed32(dst, static_cast<uint32_t>(table_magic_number() >> 32));
assert(dst->size() == original_size + kVersion0EncodedLength);
} else {
const size_t original_size = dst->size();
dst->push_back(static_cast<char>(checksum_));
metaindex_handle_.EncodeTo(dst);
index_handle_.EncodeTo(dst);
dst->resize(original_size + kNewVersionsEncodedLength - 12); // Padding
PutFixed32(dst, version());
PutFixed32(dst, static_cast<uint32_t>(table_magic_number() & 0xffffffffu));
PutFixed32(dst, static_cast<uint32_t>(table_magic_number() >> 32));
assert(dst->size() == original_size + kNewVersionsEncodedLength);
}
}
Footer::Footer(uint64_t _table_magic_number, uint32_t _version)
: version_(_version),
checksum_(kCRC32c),
table_magic_number_(_table_magic_number) {
// This should be guaranteed by constructor callers
assert(!IsLegacyFooterFormat(_table_magic_number) || version_ == 0);
}
Status Footer::DecodeFrom(Slice* input) {
assert(!HasInitializedTableMagicNumber());
assert(input != nullptr);
assert(input->size() >= kMinEncodedLength);
const char *magic_ptr =
input->data() + input->size() - kMagicNumberLengthByte;
const uint32_t magic_lo = DecodeFixed32(magic_ptr);
const uint32_t magic_hi = DecodeFixed32(magic_ptr + 4);
uint64_t magic = ((static_cast<uint64_t>(magic_hi) << 32) |
(static_cast<uint64_t>(magic_lo)));
// We check for legacy formats here and silently upconvert them
bool legacy = IsLegacyFooterFormat(magic);
if (legacy) {
magic = UpconvertLegacyFooterFormat(magic);
}
set_table_magic_number(magic);
if (legacy) {
// The size is already asserted to be at least kMinEncodedLength
// at the beginning of the function
input->remove_prefix(input->size() - kVersion0EncodedLength);
version_ = 0 /* legacy */;
checksum_ = kCRC32c;
} else {
version_ = DecodeFixed32(magic_ptr - 4);
// Footer version 1 and higher will always occupy exactly this many bytes.
// It consists of the checksum type, two block handles, padding,
// a version number, and a magic number
if (input->size() < kNewVersionsEncodedLength) {
return Status::Corruption("input is too short to be an sstable");
} else {
input->remove_prefix(input->size() - kNewVersionsEncodedLength);
}
uint32_t chksum;
if (!GetVarint32(input, &chksum)) {
return Status::Corruption("bad checksum type");
}
checksum_ = static_cast<ChecksumType>(chksum);
}
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 + kMagicNumberLengthByte;
*input = Slice(end, input->data() + input->size() - end);
}
return result;
}
std::string Footer::ToString() const {
std::string result, handle_;
result.reserve(1024);
bool legacy = IsLegacyFooterFormat(table_magic_number_);
if (legacy) {
result.append("metaindex handle: " + metaindex_handle_.ToString() + "\n ");
result.append("index handle: " + index_handle_.ToString() + "\n ");
result.append("table_magic_number: " +
rocksdb::ToString(table_magic_number_) + "\n ");
} else {
result.append("checksum: " + rocksdb::ToString(checksum_) + "\n ");
result.append("metaindex handle: " + metaindex_handle_.ToString() + "\n ");
result.append("index handle: " + index_handle_.ToString() + "\n ");
result.append("footer version: " + rocksdb::ToString(version_) + "\n ");
result.append("table_magic_number: " +
rocksdb::ToString(table_magic_number_) + "\n ");
}
return result;
}
Status ReadFooterFromFile(RandomAccessFileReader* file, uint64_t file_size,
Footer* footer, uint64_t enforce_table_magic_number) {
if (file_size < Footer::kMinEncodedLength) {
return Status::Corruption("file is too short to be an sstable");
}
char footer_space[Footer::kMaxEncodedLength];
Slice footer_input;
size_t read_offset =
(file_size > Footer::kMaxEncodedLength)
? static_cast<size_t>(file_size - Footer::kMaxEncodedLength)
: 0;
Status s = file->Read(read_offset, Footer::kMaxEncodedLength, &footer_input,
footer_space);
if (!s.ok()) return s;
// Check that we actually read the whole footer from the file. It may be
// that size isn't correct.
if (footer_input.size() < Footer::kMinEncodedLength) {
return Status::Corruption("file is too short to be an sstable");
}
s = footer->DecodeFrom(&footer_input);
if (!s.ok()) {
return s;
}
if (enforce_table_magic_number != 0 &&
enforce_table_magic_number != footer->table_magic_number()) {
return Status::Corruption("Bad table magic number");
}
return Status::OK();
}
// Without anonymous namespace here, we fail the warning -Wmissing-prototypes
namespace {
// Read a block and check its CRC
// contents is the result of reading.
// According to the implementation of file->Read, contents may not point to buf
Status ReadBlock(RandomAccessFileReader* file, const Footer& footer,
const ReadOptions& options, const BlockHandle& handle,
Slice* contents, /* result of reading */ char* buf) {
size_t n = static_cast<size_t>(handle.size());
Status s;
{
PERF_TIMER_GUARD(block_read_time);
s = file->Read(handle.offset(), n + kBlockTrailerSize, contents, buf);
}
PERF_COUNTER_ADD(block_read_count, 1);
PERF_COUNTER_ADD(block_read_byte, n + kBlockTrailerSize);
if (!s.ok()) {
return s;
}
if (contents->size() != n + kBlockTrailerSize) {
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) {
PERF_TIMER_GUARD(block_checksum_time);
uint32_t value = DecodeFixed32(data + n + 1);
uint32_t actual = 0;
switch (footer.checksum()) {
case kCRC32c:
value = crc32c::Unmask(value);
actual = crc32c::Value(data, n + 1);
break;
case kxxHash:
actual = XXH32(data, static_cast<int>(n) + 1, 0);
break;
default:
s = Status::Corruption("unknown checksum type");
}
if (s.ok() && actual != value) {
s = Status::Corruption("block checksum mismatch");
}
if (!s.ok()) {
return s;
}
}
return s;
}
} // namespace
Status ReadBlockContents(RandomAccessFileReader* file, const Footer& footer,
const ReadOptions& read_options,
const BlockHandle& handle, BlockContents* contents,
const ImmutableCFOptions &ioptions,
bool decompression_requested,
const Slice& compression_dict,
const PersistentCacheOptions& cache_options) {
Status status;
Slice slice;
size_t n = static_cast<size_t>(handle.size());
std::unique_ptr<char[]> heap_buf;
char stack_buf[DefaultStackBufferSize];
char* used_buf = nullptr;
rocksdb::CompressionType compression_type;
if (cache_options.persistent_cache &&
!cache_options.persistent_cache->IsCompressed()) {
status = PersistentCacheHelper::LookupUncompressedPage(cache_options,
handle, contents);
if (status.ok()) {
// uncompressed page is found for the block handle
return status;
} else {
// uncompressed page is not found
if (ioptions.info_log && !status.IsNotFound()) {
assert(!status.ok());
Log(InfoLogLevel::INFO_LEVEL, ioptions.info_log,
"Error reading from persistent cache. %s",
status.ToString().c_str());
}
}
}
if (cache_options.persistent_cache &&
cache_options.persistent_cache->IsCompressed()) {
// lookup uncompressed cache mode p-cache
status = PersistentCacheHelper::LookupRawPage(
cache_options, handle, &heap_buf, n + kBlockTrailerSize);
} else {
status = Status::NotFound();
}
if (status.ok()) {
// cache hit
used_buf = heap_buf.get();
slice = Slice(heap_buf.get(), n);
} else {
if (ioptions.info_log && !status.IsNotFound()) {
assert(!status.ok());
Log(InfoLogLevel::INFO_LEVEL, ioptions.info_log,
"Error reading from persistent cache. %s", status.ToString().c_str());
}
// cache miss read from device
if (decompression_requested &&
n + kBlockTrailerSize < DefaultStackBufferSize) {
// If we've got a small enough hunk of data, read it in to the
// trivially allocated stack buffer instead of needing a full malloc()
used_buf = &stack_buf[0];
} else {
heap_buf = std::unique_ptr<char[]>(new char[n + kBlockTrailerSize]);
used_buf = heap_buf.get();
}
status = ReadBlock(file, footer, read_options, handle, &slice, used_buf);
if (status.ok() && read_options.fill_cache &&
cache_options.persistent_cache &&
cache_options.persistent_cache->IsCompressed()) {
// insert to raw cache
PersistentCacheHelper::InsertRawPage(cache_options, handle, used_buf,
n + kBlockTrailerSize);
}
}
if (!status.ok()) {
return status;
}
PERF_TIMER_GUARD(block_decompress_time);
compression_type = static_cast<rocksdb::CompressionType>(slice.data()[n]);
if (decompression_requested && compression_type != kNoCompression) {
// compressed page, uncompress, update cache
status = UncompressBlockContents(slice.data(), n, contents,
footer.version(), compression_dict,
ioptions);
} else if (slice.data() != used_buf) {
// the slice content is not the buffer provided
*contents = BlockContents(Slice(slice.data(), n), false, compression_type);
} else {
// page is uncompressed, the buffer either stack or heap provided
if (used_buf == &stack_buf[0]) {
heap_buf = std::unique_ptr<char[]>(new char[n]);
memcpy(heap_buf.get(), stack_buf, n);
}
*contents = BlockContents(std::move(heap_buf), n, true, compression_type);
}
if (status.ok() && read_options.fill_cache &&
cache_options.persistent_cache &&
!cache_options.persistent_cache->IsCompressed()) {
// insert to uncompressed cache
PersistentCacheHelper::InsertUncompressedPage(cache_options, handle,
*contents);
}
return status;
}
Status UncompressBlockContentsForCompressionType(
const char* data, size_t n, BlockContents* contents,
uint32_t format_version, const Slice& compression_dict,
CompressionType compression_type, const ImmutableCFOptions &ioptions) {
std::unique_ptr<char[]> ubuf;
assert(compression_type != kNoCompression && "Invalid compression type");
StopWatchNano timer(ioptions.env,
ShouldReportDetailedTime(ioptions.env, ioptions.statistics));
int decompress_size = 0;
switch (compression_type) {
case kSnappyCompression: {
size_t ulength = 0;
static char snappy_corrupt_msg[] =
"Snappy not supported or corrupted Snappy compressed block contents";
if (!Snappy_GetUncompressedLength(data, n, &ulength)) {
return Status::Corruption(snappy_corrupt_msg);
}
ubuf.reset(new char[ulength]);
if (!Snappy_Uncompress(data, n, ubuf.get())) {
return Status::Corruption(snappy_corrupt_msg);
}
*contents = BlockContents(std::move(ubuf), ulength, true, kNoCompression);
break;
}
case kZlibCompression:
ubuf.reset(Zlib_Uncompress(
data, n, &decompress_size,
GetCompressFormatForVersion(kZlibCompression, format_version),
compression_dict));
if (!ubuf) {
static char zlib_corrupt_msg[] =
"Zlib not supported or corrupted Zlib compressed block contents";
return Status::Corruption(zlib_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
case kBZip2Compression:
ubuf.reset(BZip2_Uncompress(
data, n, &decompress_size,
GetCompressFormatForVersion(kBZip2Compression, format_version)));
if (!ubuf) {
static char bzip2_corrupt_msg[] =
"Bzip2 not supported or corrupted Bzip2 compressed block contents";
return Status::Corruption(bzip2_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
case kLZ4Compression:
ubuf.reset(LZ4_Uncompress(
data, n, &decompress_size,
GetCompressFormatForVersion(kLZ4Compression, format_version),
compression_dict));
if (!ubuf) {
static char lz4_corrupt_msg[] =
"LZ4 not supported or corrupted LZ4 compressed block contents";
return Status::Corruption(lz4_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
case kLZ4HCCompression:
ubuf.reset(LZ4_Uncompress(
data, n, &decompress_size,
GetCompressFormatForVersion(kLZ4HCCompression, format_version),
compression_dict));
if (!ubuf) {
static char lz4hc_corrupt_msg[] =
"LZ4HC not supported or corrupted LZ4HC compressed block contents";
return Status::Corruption(lz4hc_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
case kXpressCompression:
ubuf.reset(XPRESS_Uncompress(data, n, &decompress_size));
if (!ubuf) {
static char xpress_corrupt_msg[] =
"XPRESS not supported or corrupted XPRESS compressed block contents";
return Status::Corruption(xpress_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
case kZSTD:
case kZSTDNotFinalCompression:
ubuf.reset(ZSTD_Uncompress(data, n, &decompress_size, compression_dict));
if (!ubuf) {
static char zstd_corrupt_msg[] =
"ZSTD not supported or corrupted ZSTD compressed block contents";
return Status::Corruption(zstd_corrupt_msg);
}
*contents =
BlockContents(std::move(ubuf), decompress_size, true, kNoCompression);
break;
default:
return Status::Corruption("bad block type");
}
if(ShouldReportDetailedTime(ioptions.env, ioptions.statistics)){
MeasureTime(ioptions.statistics, DECOMPRESSION_TIMES_NANOS,
timer.ElapsedNanos());
MeasureTime(ioptions.statistics, BYTES_DECOMPRESSED, contents->data.size());
RecordTick(ioptions.statistics, NUMBER_BLOCK_DECOMPRESSED);
}
return Status::OK();
}
//
// The 'data' points to the raw block contents that was read in from file.
// This method allocates a new heap buffer and the raw block
// contents are uncompresed into this buffer. This
// buffer is returned via 'result' and it is upto the caller to
// free this buffer.
// format_version is the block format as defined in include/rocksdb/table.h
Status UncompressBlockContents(const char* data, size_t n,
BlockContents* contents, uint32_t format_version,
const Slice& compression_dict,
const ImmutableCFOptions &ioptions) {
assert(data[n] != kNoCompression);
return UncompressBlockContentsForCompressionType(
data, n, contents, format_version, compression_dict,
(CompressionType)data[n], ioptions);
}
} // namespace rocksdb
