105 lines
3.3 KiB
C++
105 lines
3.3 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#ifndef STORAGE_ROCKSDB_INCLUDE_TRANSACTION_LOG_ITERATOR_H_
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#define STORAGE_ROCKSDB_INCLUDE_TRANSACTION_LOG_ITERATOR_H_
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#include "rocksdb/status.h"
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#include "rocksdb/types.h"
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#include "rocksdb/write_batch.h"
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#include <memory>
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#include <vector>
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namespace rocksdb {
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class LogFile;
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typedef std::vector<std::unique_ptr<LogFile>> VectorLogPtr;
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enum WalFileType {
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/* Indicates that WAL file is in archive directory. WAL files are moved from
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* the main db directory to archive directory once they are not live and stay
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* there until cleaned up. Files are cleaned depending on archive size
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* (Options::WAL_size_limit_MB) and time since last cleaning
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* (Options::WAL_ttl_seconds).
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*/
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kArchivedLogFile = 0,
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/* Indicates that WAL file is live and resides in the main db directory */
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kAliveLogFile = 1
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} ;
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class LogFile {
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public:
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LogFile() {}
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virtual ~LogFile() {}
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// Returns log file's pathname relative to the main db dir
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// Eg. For a live-log-file = /000003.log
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// For an archived-log-file = /archive/000003.log
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virtual std::string PathName() const = 0;
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// Primary identifier for log file.
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// This is directly proportional to creation time of the log file
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virtual uint64_t LogNumber() const = 0;
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// Log file can be either alive or archived
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virtual WalFileType Type() const = 0;
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// Starting sequence number of writebatch written in this log file
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virtual SequenceNumber StartSequence() const = 0;
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// Size of log file on disk in Bytes
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virtual uint64_t SizeFileBytes() const = 0;
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};
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struct BatchResult {
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SequenceNumber sequence = 0;
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std::unique_ptr<WriteBatch> writeBatchPtr;
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};
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// A TransactionLogIterator is used to iterate over the transactions in a db.
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// One run of the iterator is continuous, i.e. the iterator will stop at the
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// beginning of any gap in sequences
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class TransactionLogIterator {
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public:
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TransactionLogIterator() {}
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virtual ~TransactionLogIterator() {}
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// An iterator is either positioned at a WriteBatch or not valid.
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// This method returns true if the iterator is valid.
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// Can read data from a valid iterator.
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virtual bool Valid() = 0;
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// Moves the iterator to the next WriteBatch.
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// REQUIRES: Valid() to be true.
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virtual void Next() = 0;
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// Returns ok if the iterator is valid.
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// Returns the Error when something has gone wrong.
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virtual Status status() = 0;
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// If valid return's the current write_batch and the sequence number of the
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// earliest transaction contained in the batch.
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// ONLY use if Valid() is true and status() is OK.
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virtual BatchResult GetBatch() = 0;
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// The read options for TransactionLogIterator.
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struct ReadOptions {
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// If true, all data read from underlying storage will be
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// verified against corresponding checksums.
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// Default: true
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bool verify_checksums_;
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ReadOptions() : verify_checksums_(true) {}
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explicit ReadOptions(bool verify_checksums)
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: verify_checksums_(verify_checksums) {}
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};
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};
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} // namespace rocksdb
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#endif // STORAGE_ROCKSDB_INCLUDE_TRANSACTION_LOG_ITERATOR_H_
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