blob: 9c76b92aefeb198d82c3782e3e7273b37cfe8da8 [file] [log] [blame]
// 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).
#pragma once
#include <memory>
#include <string>
#include "rocksdb/slice.h"
#include "rocksdb/status.h"
#include "utilities/blob_db/blob_log_format.h"
namespace rocksdb {
class SequentialFileReader;
class Logger;
namespace blob_db {
* Reader is a general purpose log stream reader implementation. The actual job
* of reading from the device is implemented by the SequentialFile interface.
* Please see Writer for details on the file and record layout.
class Reader {
enum ReadLevel {
// Create a reader that will return log records from "*file".
// "*file" must remain live while this Reader is in use.
// If "reporter" is non-nullptr, it is notified whenever some data is
// dropped due to a detected corruption. "*reporter" must remain
// live while this Reader is in use.
// If "checksum" is true, verify checksums if available.
// The Reader will start reading at the first record located at physical
// position >= initial_offset within the file.
Reader(std::shared_ptr<Logger> info_log,
std::unique_ptr<SequentialFileReader>&& file);
~Reader() = default;
// No copying allowed
Reader(const Reader&) = delete;
Reader& operator=(const Reader&) = delete;
Status ReadHeader(BlobLogHeader* header);
// Read the next record into *record. Returns true if read
// successfully, false if we hit end of the input. May use
// "*scratch" as temporary storage. The contents filled in *record
// will only be valid until the next mutating operation on this
// reader or the next mutation to *scratch.
// If blob_offset is non-null, return offset of the blob through it.
Status ReadRecord(BlobLogRecord* record, ReadLevel level = kReadHeader,
uint64_t* blob_offset = nullptr);
Status ReadSlice(uint64_t size, Slice* slice, std::string* buf);
SequentialFileReader* file() { return file_.get(); }
void ResetNextByte() { next_byte_ = 0; }
uint64_t GetNextByte() const { return next_byte_; }
const SequentialFileReader* file_reader() const { return file_.get(); }
std::shared_ptr<Logger> info_log_;
const std::unique_ptr<SequentialFileReader> file_;
std::string backing_store_;
Slice buffer_;
// which byte to read next. For asserting proper usage
uint64_t next_byte_;
} // namespace blob_db
} // namespace rocksdb
#endif // ROCKSDB_LITE