/usr/include/rocksdb/wal_filter.h is in librocksdb-dev 5.8.8-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 | // 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 <string>
#include <map>
namespace rocksdb {
class WriteBatch;
// WALFilter allows an application to inspect write-ahead-log (WAL)
// records or modify their processing on recovery.
// Please see the details below.
class WalFilter {
public:
enum class WalProcessingOption {
// Continue processing as usual
kContinueProcessing = 0,
// Ignore the current record but continue processing of log(s)
kIgnoreCurrentRecord = 1,
// Stop replay of logs and discard logs
// Logs won't be replayed on subsequent recovery
kStopReplay = 2,
// Corrupted record detected by filter
kCorruptedRecord = 3,
// Marker for enum count
kWalProcessingOptionMax = 4
};
virtual ~WalFilter() {}
// Provide ColumnFamily->LogNumber map to filter
// so that filter can determine whether a log number applies to a given
// column family (i.e. that log hasn't been flushed to SST already for the
// column family).
// We also pass in name->id map as only name is known during
// recovery (as handles are opened post-recovery).
// while write batch callbacks happen in terms of column family id.
//
// @params cf_lognumber_map column_family_id to lognumber map
// @params cf_name_id_map column_family_name to column_family_id map
virtual void ColumnFamilyLogNumberMap(
const std::map<uint32_t, uint64_t>& cf_lognumber_map,
const std::map<std::string, uint32_t>& cf_name_id_map) {}
// LogRecord is invoked for each log record encountered for all the logs
// during replay on logs on recovery. This method can be used to:
// * inspect the record (using the batch parameter)
// * ignoring current record
// (by returning WalProcessingOption::kIgnoreCurrentRecord)
// * reporting corrupted record
// (by returning WalProcessingOption::kCorruptedRecord)
// * stop log replay
// (by returning kStop replay) - please note that this implies
// discarding the logs from current record onwards.
//
// @params log_number log_number of the current log.
// Filter might use this to determine if the log
// record is applicable to a certain column family.
// @params log_file_name log file name - only for informational purposes
// @params batch batch encountered in the log during recovery
// @params new_batch new_batch to populate if filter wants to change
// the batch (for example to filter some records out,
// or alter some records).
// Please note that the new batch MUST NOT contain
// more records than original, else recovery would
// be failed.
// @params batch_changed Whether batch was changed by the filter.
// It must be set to true if new_batch was populated,
// else new_batch has no effect.
// @returns Processing option for the current record.
// Please see WalProcessingOption enum above for
// details.
virtual WalProcessingOption LogRecordFound(unsigned long long log_number,
const std::string& log_file_name,
const WriteBatch& batch,
WriteBatch* new_batch,
bool* batch_changed) {
// Default implementation falls back to older function for compatibility
return LogRecord(batch, new_batch, batch_changed);
}
// Please see the comments for LogRecord above. This function is for
// compatibility only and contains a subset of parameters.
// New code should use the function above.
virtual WalProcessingOption LogRecord(const WriteBatch& batch,
WriteBatch* new_batch,
bool* batch_changed) const {
return WalProcessingOption::kContinueProcessing;
}
// Returns a name that identifies this WAL filter.
// The name will be printed to LOG file on start up for diagnosis.
virtual const char* Name() const = 0;
};
} // namespace rocksdb
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