| // 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 |
