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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).
#pragma once
#include <cstdint>
#include <memory>
#include <string>
#include "db/blob/blob_log_format.h"
#include "rocksdb/slice.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
namespace ROCKSDB_NAMESPACE {
class WritableFileWriter;
class SystemClock;
/**
* BlobLogWriter is the blob log stream writer. It provides an append-only
* abstraction for writing blob data.
*
*
* Look at blob_db_format.h to see the details of the record formats.
*/
class BlobLogWriter {
public:
// Create a writer that will append data to "*dest".
// "*dest" must be initially empty.
// "*dest" must remain live while this BlobLogWriter is in use.
BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest, SystemClock* clock,
Statistics* statistics, uint64_t log_number, bool use_fsync,
bool do_flush, uint64_t boffset = 0);
// No copying allowed
BlobLogWriter(const BlobLogWriter&) = delete;
BlobLogWriter& operator=(const BlobLogWriter&) = delete;
~BlobLogWriter();
static void ConstructBlobHeader(std::string* buf, const Slice& key,
const Slice& val, uint64_t expiration);
Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
uint64_t* blob_offset);
Status AddRecord(const Slice& key, const Slice& val, uint64_t expiration,
uint64_t* key_offset, uint64_t* blob_offset);
Status EmitPhysicalRecord(const std::string& headerbuf, const Slice& key,
const Slice& val, uint64_t* key_offset,
uint64_t* blob_offset);
Status AppendFooter(BlobLogFooter& footer, std::string* checksum_method,
std::string* checksum_value);
Status WriteHeader(BlobLogHeader& header);
WritableFileWriter* file() { return dest_.get(); }
const WritableFileWriter* file() const { return dest_.get(); }
uint64_t get_log_number() const { return log_number_; }
Status Sync();
private:
std::unique_ptr<WritableFileWriter> dest_;
SystemClock* clock_;
Statistics* statistics_;
uint64_t log_number_;
uint64_t block_offset_; // Current offset in block
bool use_fsync_;
bool do_flush_;
public:
enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };
ElemType last_elem_type_;
};
} // namespace ROCKSDB_NAMESPACE
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