419b93c56f
Summary: Previously each time we write a blob we write blog_record_header + key + value + blob_record_footer to blob log. The footer only contains a sequence and a crc for the sequence number. The sequence number was used in garbage collection to verify the value is recent. After #2703 we moved to use optimistic transaction and no longer use sequence number from the footer. Remove the footer altogether. There's another usage of sequence number and we are keeping it: Each blob log file keep track of sequence number range of keys in it, and use it to check if it is reference by a snapshot, before being deleted. Closes https://github.com/facebook/rocksdb/pull/3005 Differential Revision: D6057585 Pulled By: yiwu-arbug fbshipit-source-id: d6da53c457a316e9723f359a1b47facfc3ffe090
96 lines
2.8 KiB
C++
96 lines
2.8 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#ifndef ROCKSDB_LITE
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#include <cstdint>
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#include <memory>
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#include <string>
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/types.h"
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#include "utilities/blob_db/blob_log_format.h"
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namespace rocksdb {
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class WritableFileWriter;
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namespace blob_db {
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/**
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* Writer is the blob log stream writer. It provides an append-only
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* abstraction for writing blob data.
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*
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*
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* Look at blob_db_format.h to see the details of the record formats.
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*/
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class Writer {
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public:
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// Create a writer that will append data to "*dest".
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// "*dest" must be initially empty.
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// "*dest" must remain live while this Writer is in use.
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explicit Writer(std::unique_ptr<WritableFileWriter>&& dest,
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uint64_t log_number, uint64_t bpsync, bool use_fsync,
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uint64_t boffset = 0);
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~Writer();
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static void ConstructBlobHeader(std::string* headerbuf, const Slice& key,
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const Slice& val, uint64_t ttl, int64_t ts);
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Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
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uint64_t* blob_offset);
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Status AddRecord(const Slice& key, const Slice& val, uint64_t* key_offset,
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uint64_t* blob_offset, uint64_t ttl);
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Status EmitPhysicalRecord(const std::string& headerbuf, const Slice& key,
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const Slice& val, uint64_t* key_offset,
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uint64_t* blob_offset);
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Status AppendFooter(const BlobLogFooter& footer);
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Status WriteHeader(const BlobLogHeader& header);
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WritableFileWriter* file() { return dest_.get(); }
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const WritableFileWriter* file() const { return dest_.get(); }
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uint64_t get_log_number() const { return log_number_; }
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bool ShouldSync() const { return block_offset_ > next_sync_offset_; }
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void Sync();
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void ResetSyncPointer() { next_sync_offset_ += bytes_per_sync_; }
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private:
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std::unique_ptr<WritableFileWriter> dest_;
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uint64_t log_number_;
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uint64_t block_offset_; // Current offset in block
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uint64_t bytes_per_sync_;
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uint64_t next_sync_offset_;
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bool use_fsync_;
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// crc32c values for all supported record types. These are
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// pre-computed to reduce the overhead of computing the crc of the
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// record type stored in the header.
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uint32_t type_crc_[kMaxRecordType + 1];
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// No copying allowed
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Writer(const Writer&) = delete;
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Writer& operator=(const Writer&) = delete;
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public:
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enum ElemType { kEtNone, kEtFileHdr, kEtRecord, kEtFileFooter };
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ElemType last_elem_type_;
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};
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} // namespace blob_db
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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