a693341604
Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7086 Test Plan: `make check` Reviewed By: zhichao-cao Differential Revision: D22395420 Pulled By: ltamasi fbshipit-source-id: 088a20097bd6b73b0c433cd79725779f97ec04f2
81 lines
2.3 KiB
C++
81 lines
2.3 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 "db/blob/blob_log_format.h"
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#include "file/random_access_file_reader.h"
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#include "rocksdb/env.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/statistics.h"
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#include "rocksdb/status.h"
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namespace ROCKSDB_NAMESPACE {
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class SequentialFileReader;
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class Logger;
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/**
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* BlobLogReader is a general purpose log stream reader implementation. The
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* actual job of reading from the device is implemented by the SequentialFile
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* 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 BlobLogReader {
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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 BlobLogReader is in use.
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BlobLogReader(std::unique_ptr<RandomAccessFileReader>&& file_reader, Env* env,
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Statistics* statistics);
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// No copying allowed
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BlobLogReader(const BlobLogReader&) = delete;
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BlobLogReader& operator=(const BlobLogReader&) = delete;
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~BlobLogReader() = default;
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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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void ResetNextByte() { next_byte_ = 0; }
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uint64_t GetNextByte() const { return next_byte_; }
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private:
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Status ReadSlice(uint64_t size, Slice* slice, char* buf);
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const std::unique_ptr<RandomAccessFileReader> file_;
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Env* env_;
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Statistics* statistics_;
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Slice buffer_;
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char header_buf_[BlobLogRecord::kHeaderSize];
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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 ROCKSDB_NAMESPACE
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#endif // ROCKSDB_LITE
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