[−][src]Trait rocks::wal_filter::WalFilter

pub trait WalFilter {
    pub fn column_family_log_number_map(
        &mut self, 
        cf_lognumber_map: &BTreeMap<u32, u64>, 
        cf_name_id_map: &BTreeMap<String, u32>
    ) { ... }

    pub fn log_record_found(
        &self, 
        log_number: u64, 
        log_file_name: &str, 
        batch: &WriteBatch
    ) -> WalProcessingOption { ... }

    pub fn name(&self) -> &str { ... }
}

WALFilter allows an application to inspect write-ahead-log (WAL) records or modify their processing on recovery.

Provided methods

pub fn column_family_log_number_map(
    &mut self,
    cf_lognumber_map: &BTreeMap<u32, u64>,
    cf_name_id_map: &BTreeMap<String, u32>
)[src]

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.

Arguments

  • cf_lognumber_map - column_family_id to lognumber map
  • cf_name_id_map - column_family_name to column_family_id map

pub fn log_record_found(
    &self,
    log_number: u64,
    log_file_name: &str,
    batch: &WriteBatch
) -> WalProcessingOption[src]

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.

Arguments

  • 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.

  • log_file_name - log file name - only for informational purposes

  • batch - batch encountered in the log during recovery

  • 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.

  • 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.

pub fn name(&self) -> &str[src]

Returns a name that identifies this WAL filter.

The name will be printed to LOG file on start up for diagnosis.

Loading content...

Implementors

Loading content...