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rocksdb/db/blob/blob_file_reader.cc

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#include "db/blob/blob_file_reader.h"
#include <cassert>
#include <string>
#include "db/blob/blob_log_format.h"
#include "file/file_prefetch_buffer.h"
#include "file/filename.h"
#include "monitoring/statistics.h"
#include "options/cf_options.h"
#include "rocksdb/file_system.h"
#include "rocksdb/slice.h"
#include "rocksdb/status.h"
#include "table/multiget_context.h"
#include "test_util/sync_point.h"
#include "util/compression.h"
#include "util/crc32c.h"
#include "util/stop_watch.h"
namespace ROCKSDB_NAMESPACE {
Status BlobFileReader::Create(
const ImmutableOptions& immutable_options, const FileOptions& file_options,
uint32_t column_family_id, HistogramImpl* blob_file_read_hist,
uint64_t blob_file_number, const std::shared_ptr<IOTracer>& io_tracer,
std::unique_ptr<BlobFileReader>* blob_file_reader) {
assert(blob_file_reader);
assert(!*blob_file_reader);
uint64_t file_size = 0;
std::unique_ptr<RandomAccessFileReader> file_reader;
{
const Status s =
OpenFile(immutable_options, file_options, blob_file_read_hist,
blob_file_number, io_tracer, &file_size, &file_reader);
if (!s.ok()) {
return s;
}
}
assert(file_reader);
Statistics* const statistics = immutable_options.stats;
CompressionType compression_type = kNoCompression;
{
const Status s = ReadHeader(file_reader.get(), column_family_id, statistics,
&compression_type);
if (!s.ok()) {
return s;
}
}
{
const Status s = ReadFooter(file_reader.get(), file_size, statistics);
if (!s.ok()) {
return s;
}
}
blob_file_reader->reset(
new BlobFileReader(std::move(file_reader), file_size, compression_type,
immutable_options.clock, statistics));
return Status::OK();
}
Status BlobFileReader::OpenFile(
const ImmutableOptions& immutable_options, const FileOptions& file_opts,
HistogramImpl* blob_file_read_hist, uint64_t blob_file_number,
const std::shared_ptr<IOTracer>& io_tracer, uint64_t* file_size,
std::unique_ptr<RandomAccessFileReader>* file_reader) {
assert(file_size);
assert(file_reader);
const auto& cf_paths = immutable_options.cf_paths;
assert(!cf_paths.empty());
const std::string blob_file_path =
BlobFileName(cf_paths.front().path, blob_file_number);
FileSystem* const fs = immutable_options.fs.get();
assert(fs);
constexpr IODebugContext* dbg = nullptr;
{
TEST_SYNC_POINT("BlobFileReader::OpenFile:GetFileSize");
const Status s =
fs->GetFileSize(blob_file_path, IOOptions(), file_size, dbg);
if (!s.ok()) {
return s;
}
}
if (*file_size < BlobLogHeader::kSize + BlobLogFooter::kSize) {
return Status::Corruption("Malformed blob file");
}
std::unique_ptr<FSRandomAccessFile> file;
{
TEST_SYNC_POINT("BlobFileReader::OpenFile:NewRandomAccessFile");
const Status s =
fs->NewRandomAccessFile(blob_file_path, file_opts, &file, dbg);
if (!s.ok()) {
return s;
}
}
assert(file);
if (immutable_options.advise_random_on_open) {
file->Hint(FSRandomAccessFile::kRandom);
}
file_reader->reset(new RandomAccessFileReader(
std::move(file), blob_file_path, immutable_options.clock, io_tracer,
immutable_options.stats, BLOB_DB_BLOB_FILE_READ_MICROS,
blob_file_read_hist, immutable_options.rate_limiter.get(),
immutable_options.listeners));
return Status::OK();
}
Status BlobFileReader::ReadHeader(const RandomAccessFileReader* file_reader,
uint32_t column_family_id,
Statistics* statistics,
CompressionType* compression_type) {
assert(file_reader);
assert(compression_type);
Slice header_slice;
Buffer buf;
AlignedBuf aligned_buf;
{
TEST_SYNC_POINT("BlobFileReader::ReadHeader:ReadFromFile");
constexpr uint64_t read_offset = 0;
constexpr size_t read_size = BlobLogHeader::kSize;
// TODO: rate limit reading headers from blob files.
const Status s = ReadFromFile(file_reader, read_offset, read_size,
statistics, &header_slice, &buf, &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */);
if (!s.ok()) {
return s;
}
TEST_SYNC_POINT_CALLBACK("BlobFileReader::ReadHeader:TamperWithResult",
&header_slice);
}
BlobLogHeader header;
{
const Status s = header.DecodeFrom(header_slice);
if (!s.ok()) {
return s;
}
}
constexpr ExpirationRange no_expiration_range;
if (header.has_ttl || header.expiration_range != no_expiration_range) {
return Status::Corruption("Unexpected TTL blob file");
}
if (header.column_family_id != column_family_id) {
return Status::Corruption("Column family ID mismatch");
}
*compression_type = header.compression;
return Status::OK();
}
Status BlobFileReader::ReadFooter(const RandomAccessFileReader* file_reader,
uint64_t file_size, Statistics* statistics) {
assert(file_size >= BlobLogHeader::kSize + BlobLogFooter::kSize);
assert(file_reader);
Slice footer_slice;
Buffer buf;
AlignedBuf aligned_buf;
{
TEST_SYNC_POINT("BlobFileReader::ReadFooter:ReadFromFile");
const uint64_t read_offset = file_size - BlobLogFooter::kSize;
constexpr size_t read_size = BlobLogFooter::kSize;
// TODO: rate limit reading footers from blob files.
const Status s = ReadFromFile(file_reader, read_offset, read_size,
statistics, &footer_slice, &buf, &aligned_buf,
Env::IO_TOTAL /* rate_limiter_priority */);
if (!s.ok()) {
return s;
}
TEST_SYNC_POINT_CALLBACK("BlobFileReader::ReadFooter:TamperWithResult",
&footer_slice);
}
BlobLogFooter footer;
{
const Status s = footer.DecodeFrom(footer_slice);
if (!s.ok()) {
return s;
}
}
constexpr ExpirationRange no_expiration_range;
if (footer.expiration_range != no_expiration_range) {
return Status::Corruption("Unexpected TTL blob file");
}
return Status::OK();
}
Status BlobFileReader::ReadFromFile(const RandomAccessFileReader* file_reader,
uint64_t read_offset, size_t read_size,
Statistics* statistics, Slice* slice,
Buffer* buf, AlignedBuf* aligned_buf,
Env::IOPriority rate_limiter_priority) {
assert(slice);
assert(buf);
assert(aligned_buf);
assert(file_reader);
RecordTick(statistics, BLOB_DB_BLOB_FILE_BYTES_READ, read_size);
Status s;
if (file_reader->use_direct_io()) {
constexpr char* scratch = nullptr;
s = file_reader->Read(IOOptions(), read_offset, read_size, slice, scratch,
aligned_buf, rate_limiter_priority);
} else {
buf->reset(new char[read_size]);
constexpr AlignedBuf* aligned_scratch = nullptr;
s = file_reader->Read(IOOptions(), read_offset, read_size, slice,
buf->get(), aligned_scratch, rate_limiter_priority);
}
if (!s.ok()) {
return s;
}
if (slice->size() != read_size) {
return Status::Corruption("Failed to read data from blob file");
}
return Status::OK();
}
BlobFileReader::BlobFileReader(
std::unique_ptr<RandomAccessFileReader>&& file_reader, uint64_t file_size,
CompressionType compression_type, SystemClock* clock,
Statistics* statistics)
: file_reader_(std::move(file_reader)),
file_size_(file_size),
compression_type_(compression_type),
clock_(clock),
statistics_(statistics) {
assert(file_reader_);
}
BlobFileReader::~BlobFileReader() = default;
Status BlobFileReader::GetBlob(const ReadOptions& read_options,
const Slice& user_key, uint64_t offset,
uint64_t value_size,
CompressionType compression_type,
FilePrefetchBuffer* prefetch_buffer,
PinnableSlice* value,
uint64_t* bytes_read) const {
assert(value);
const uint64_t key_size = user_key.size();
if (!IsValidBlobOffset(offset, key_size, value_size, file_size_)) {
return Status::Corruption("Invalid blob offset");
}
if (compression_type != compression_type_) {
return Status::Corruption("Compression type mismatch when reading blob");
}
// Note: if verify_checksum is set, we read the entire blob record to be able
// to perform the verification; otherwise, we just read the blob itself. Since
// the offset in BlobIndex actually points to the blob value, we need to make
// an adjustment in the former case.
const uint64_t adjustment =
read_options.verify_checksums
? BlobLogRecord::CalculateAdjustmentForRecordHeader(key_size)
: 0;
assert(offset >= adjustment);
const uint64_t record_offset = offset - adjustment;
const uint64_t record_size = value_size + adjustment;
Slice record_slice;
Buffer buf;
AlignedBuf aligned_buf;
bool prefetched = false;
if (prefetch_buffer) {
Status s;
constexpr bool for_compaction = true;
prefetched = prefetch_buffer->TryReadFromCache(
IOOptions(), file_reader_.get(), record_offset,
static_cast<size_t>(record_size), &record_slice, &s,
read_options.rate_limiter_priority, for_compaction);
if (!s.ok()) {
return s;
}
}
if (!prefetched) {
TEST_SYNC_POINT("BlobFileReader::GetBlob:ReadFromFile");
PERF_COUNTER_ADD(blob_read_count, 1);
PERF_COUNTER_ADD(blob_read_byte, record_size);
PERF_TIMER_GUARD(blob_read_time);
const Status s = ReadFromFile(file_reader_.get(), record_offset,
static_cast<size_t>(record_size), statistics_,
&record_slice, &buf, &aligned_buf,
read_options.rate_limiter_priority);
if (!s.ok()) {
return s;
}
}
TEST_SYNC_POINT_CALLBACK("BlobFileReader::GetBlob:TamperWithResult",
&record_slice);
if (read_options.verify_checksums) {
const Status s = VerifyBlob(record_slice, user_key, value_size);
if (!s.ok()) {
return s;
}
}
const Slice value_slice(record_slice.data() + adjustment, value_size);
{
const Status s = UncompressBlobIfNeeded(value_slice, compression_type,
clock_, statistics_, value);
if (!s.ok()) {
return s;
}
}
if (bytes_read) {
*bytes_read = record_size;
}
return Status::OK();
}
void BlobFileReader::MultiGetBlob(const ReadOptions& read_options,
autovector<BlobReadRequest*>& blob_reqs,
uint64_t* bytes_read) const {
const size_t num_blobs = blob_reqs.size();
assert(num_blobs > 0);
assert(num_blobs <= MultiGetContext::MAX_BATCH_SIZE);
#ifndef NDEBUG
for (size_t i = 0; i < num_blobs - 1; ++i) {
assert(blob_reqs[i]->offset <= blob_reqs[i + 1]->offset);
}
#endif // !NDEBUG
std::vector<FSReadRequest> read_reqs;
autovector<uint64_t> adjustments;
uint64_t total_len = 0;
read_reqs.reserve(num_blobs);
for (size_t i = 0; i < num_blobs; ++i) {
const size_t key_size = blob_reqs[i]->user_key->size();
const uint64_t offset = blob_reqs[i]->offset;
const uint64_t value_size = blob_reqs[i]->len;
if (!IsValidBlobOffset(offset, key_size, value_size, file_size_)) {
*blob_reqs[i]->status = Status::Corruption("Invalid blob offset");
continue;
}
if (blob_reqs[i]->compression != compression_type_) {
*blob_reqs[i]->status =
Status::Corruption("Compression type mismatch when reading a blob");
continue;
}
const uint64_t adjustment =
read_options.verify_checksums
? BlobLogRecord::CalculateAdjustmentForRecordHeader(key_size)
: 0;
assert(blob_reqs[i]->offset >= adjustment);
adjustments.push_back(adjustment);
FSReadRequest read_req;
read_req.offset = blob_reqs[i]->offset - adjustment;
read_req.len = blob_reqs[i]->len + adjustment;
read_reqs.emplace_back(read_req);
total_len += read_req.len;
}
RecordTick(statistics_, BLOB_DB_BLOB_FILE_BYTES_READ, total_len);
Buffer buf;
AlignedBuf aligned_buf;
Status s;
bool direct_io = file_reader_->use_direct_io();
if (direct_io) {
for (size_t i = 0; i < read_reqs.size(); ++i) {
read_reqs[i].scratch = nullptr;
}
} else {
buf.reset(new char[total_len]);
std::ptrdiff_t pos = 0;
for (size_t i = 0; i < read_reqs.size(); ++i) {
read_reqs[i].scratch = buf.get() + pos;
pos += read_reqs[i].len;
}
}
TEST_SYNC_POINT("BlobFileReader::MultiGetBlob:ReadFromFile");
PERF_COUNTER_ADD(blob_read_count, num_blobs);
PERF_COUNTER_ADD(blob_read_byte, total_len);
s = file_reader_->MultiRead(IOOptions(), read_reqs.data(), read_reqs.size(),
direct_io ? &aligned_buf : nullptr,
read_options.rate_limiter_priority);
if (!s.ok()) {
for (auto& req : read_reqs) {
req.status.PermitUncheckedError();
}
for (auto& req : blob_reqs) {
assert(req->status);
if (!req->status->IsCorruption()) {
// Avoid overwriting corruption status.
*req->status = s;
}
}
return;
}
assert(s.ok());
uint64_t total_bytes = 0;
for (size_t i = 0, j = 0; i < num_blobs; ++i) {
assert(blob_reqs[i]->status);
if (!blob_reqs[i]->status->ok()) {
continue;
}
assert(j < read_reqs.size());
auto& req = read_reqs[j++];
const auto& record_slice = req.result;
if (req.status.ok() && record_slice.size() != req.len) {
req.status = IOStatus::Corruption("Failed to read data from blob file");
}
*blob_reqs[i]->status = req.status;
if (!blob_reqs[i]->status->ok()) {
continue;
}
// Verify checksums if enabled
if (read_options.verify_checksums) {
*blob_reqs[i]->status =
VerifyBlob(record_slice, *blob_reqs[i]->user_key, blob_reqs[i]->len);
if (!blob_reqs[i]->status->ok()) {
continue;
}
}
// Uncompress blob if needed
Slice value_slice(record_slice.data() + adjustments[i], blob_reqs[i]->len);
*blob_reqs[i]->status =
UncompressBlobIfNeeded(value_slice, compression_type_, clock_,
statistics_, blob_reqs[i]->result);
if (blob_reqs[i]->status->ok()) {
total_bytes += record_slice.size();
}
}
if (bytes_read) {
*bytes_read = total_bytes;
}
}
Status BlobFileReader::VerifyBlob(const Slice& record_slice,
const Slice& user_key, uint64_t value_size) {
PERF_TIMER_GUARD(blob_checksum_time);
BlobLogRecord record;
const Slice header_slice(record_slice.data(), BlobLogRecord::kHeaderSize);
{
const Status s = record.DecodeHeaderFrom(header_slice);
if (!s.ok()) {
return s;
}
}
if (record.key_size != user_key.size()) {
return Status::Corruption("Key size mismatch when reading blob");
}
if (record.value_size != value_size) {
return Status::Corruption("Value size mismatch when reading blob");
}
record.key =
Slice(record_slice.data() + BlobLogRecord::kHeaderSize, record.key_size);
if (record.key != user_key) {
return Status::Corruption("Key mismatch when reading blob");
}
record.value = Slice(record.key.data() + record.key_size, value_size);
{
TEST_SYNC_POINT_CALLBACK("BlobFileReader::VerifyBlob:CheckBlobCRC",
&record);
const Status s = record.CheckBlobCRC();
if (!s.ok()) {
return s;
}
}
return Status::OK();
}
Status BlobFileReader::UncompressBlobIfNeeded(const Slice& value_slice,
CompressionType compression_type,
SystemClock* clock,
Statistics* statistics,
PinnableSlice* value) {
assert(value);
if (compression_type == kNoCompression) {
SaveValue(value_slice, value);
return Status::OK();
}
UncompressionContext context(compression_type);
UncompressionInfo info(context, UncompressionDict::GetEmptyDict(),
compression_type);
size_t uncompressed_size = 0;
constexpr uint32_t compression_format_version = 2;
constexpr MemoryAllocator* allocator = nullptr;
CacheAllocationPtr output;
{
PERF_TIMER_GUARD(blob_decompress_time);
StopWatch stop_watch(clock, statistics, BLOB_DB_DECOMPRESSION_MICROS);
output = UncompressData(info, value_slice.data(), value_slice.size(),
&uncompressed_size, compression_format_version,
allocator);
}
TEST_SYNC_POINT_CALLBACK(
"BlobFileReader::UncompressBlobIfNeeded:TamperWithResult", &output);
if (!output) {
return Status::Corruption("Unable to uncompress blob");
}
SaveValue(Slice(output.get(), uncompressed_size), value);
return Status::OK();
}
void BlobFileReader::SaveValue(const Slice& src, PinnableSlice* dst) {
assert(dst);
if (dst->IsPinned()) {
dst->Reset();
}
dst->PinSelf(src);
}
} // namespace ROCKSDB_NAMESPACE