Package dk.netarkivet.wayback.aggregator

The Aggregator takes care of sorting the raw index files generated by the indexer and merge the files into larger index files usable by Wayback. Once every WaybackSettings.WAYBACK_AGGREGATOR_AGGREGATION_INTERVAL an index aggregation is run. An Aggregation process consists of:

• All new index files found in the WaybackSettings.WAYBACK_AGGREGATOR_OUTPUT_DIR are sorted and merged into a temp intermediate index file.
• The temp intermediate index file is merged into the working intermediate index
• If the Intermediate Index file size exceeds WaybackSettings.WAYBACK_AGGREGATOR_MAX_INTERMEDIATE_INDEX_FILE_SIZE the following sequence occures
  • The currently active wayback index file is checked to see if it can contain indexes from the new intermediate file, without reaching the WaybackSettings.WAYBACK_AGGREGATOR_MAX_MAIN_INDEX_FILE_SIZE limit
  • If the limit isn't reach the intermediate index file is merged into the active index file ('wayback.index')
  • Else the main index file is renamed with a unique name containing the current timestamp and a new wayback main index file is created. This is set to be the active index file, and the intermediate indexes are merged to this file.
• The original unsorted index files are deleted

Class Summary

Class	Description
AggregationWorker	The AggregationWorker singleton contains the schedule and file bookkeeping functionality needed in the aggregation of indexes.
AggregatorApplication	This wrapper class is used to start the AggregationWorker inside Jetty.
IndexAggregator	Encapsulates the functionality for sorting and merging index files.