3ebb7ba7b9
Summary: Changing blob file format and some code cleanup around the change. The change with blob log format are: * Remove timestamp field in blob file header, blob file footer and blob records. The field is not being use and often confuse with expiration field. * Blob file header now come with column family id, which always equal to default column family id. It leaves room for future support of column family. * Compression field in blob file header now is a standalone byte (instead of compact encode with flags field) * Blob file footer now come with its own crc. * Key length now being uint64_t instead of uint32_t * Blob CRC now checksum both key and value (instead of value only). * Some reordering of the fields. The list of cleanups: * Better inline comments in blob_log_format.h * rename ttlrange_t and snrange_t to ExpirationRange and SequenceRange respectively. * simplify blob_db::Reader * Move crc checking logic to inside blob_log_format.cc Closes https://github.com/facebook/rocksdb/pull/3081 Differential Revision: D6171304 Pulled By: yiwu-arbug fbshipit-source-id: e4373e0d39264441b7e2fbd0caba93ddd99ea2af
93 lines
2.7 KiB
C++
93 lines
2.7 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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//
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#pragma once
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#ifndef ROCKSDB_LITE
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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 "utilities/blob_db/blob_log_format.h"
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namespace rocksdb {
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class SequentialFileReader;
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class Logger;
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namespace blob_db {
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/**
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* Reader is a general purpose log stream reader implementation. The actual job
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* of reading from the device is implemented by the SequentialFile interface.
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*
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* Please see Writer for details on the file and record layout.
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*/
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class Reader {
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public:
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enum ReadLevel {
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kReadHeader,
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kReadHeaderKey,
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kReadHeaderKeyBlob,
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};
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// Create a reader that will return log records from "*file".
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// "*file" must remain live while this Reader is in use.
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//
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// If "reporter" is non-nullptr, it is notified whenever some data is
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// dropped due to a detected corruption. "*reporter" must remain
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// live while this Reader is in use.
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//
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// If "checksum" is true, verify checksums if available.
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//
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// The Reader will start reading at the first record located at physical
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// position >= initial_offset within the file.
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Reader(std::shared_ptr<Logger> info_log,
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std::unique_ptr<SequentialFileReader>&& file);
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~Reader() = default;
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// No copying allowed
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Reader(const Reader&) = delete;
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Reader& operator=(const Reader&) = delete;
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Status ReadHeader(BlobLogHeader* header);
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// Read the next record into *record. Returns true if read
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// successfully, false if we hit end of the input. May use
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// "*scratch" as temporary storage. The contents filled in *record
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// will only be valid until the next mutating operation on this
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// reader or the next mutation to *scratch.
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// If blob_offset is non-null, return offset of the blob through it.
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Status ReadRecord(BlobLogRecord* record, ReadLevel level = kReadHeader,
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uint64_t* blob_offset = nullptr);
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Status ReadSlice(uint64_t size, Slice* slice, std::string* buf);
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SequentialFileReader* file() { return file_.get(); }
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void ResetNextByte() { next_byte_ = 0; }
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uint64_t GetNextByte() const { return next_byte_; }
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const SequentialFileReader* file_reader() const { return file_.get(); }
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private:
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std::shared_ptr<Logger> info_log_;
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const std::unique_ptr<SequentialFileReader> file_;
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std::string backing_store_;
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Slice buffer_;
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// which byte to read next. For asserting proper usage
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uint64_t next_byte_;
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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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