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Zach BrownandZach Brown
f8e1812288
This introduces the srch mechanism that we'll use to accelerate finding files based on the presence of a given named xattr. This is an optimized version of the initial prototype that was using locked btree items for .indx. xattrs. This is built around specific compressed data structures, having the operation cost match the reality of orders of magnitude more writers than readers, and adopting a relaxed locking model. Combine all of this and maintaining the xattrs no longer tanks creation rates while maintaining excellent search latencies, given that searches are defined as rare and relatively expensive. The core data type is the srch entry which maps a hashed name to an inode number. Mounts can append entries to the end of unsorted log files during their transaction. The server tracks these files and rotates them into a list of files as they get large enough. Mounts have compaction work that regularly asks the server for a set of files to read and combine into a single sorted output file. The server only initiates compactions when it sees a number of files of roughly the same size. Searches then walk all the commited srch files, both log files and sorted compacted files, looking for entries that associate an xattr name with an inode number. Signed-off-by: Zach Brown <zab@versity.com>