Benedict created CASSANDRA-8496:
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Summary: Remove MemtablePostFlusher
Key: CASSANDRA-8496
URL: https://issues.apache.org/jira/browse/CASSANDRA-8496
Project: Cassandra
Issue Type: Improvement
Components: Core
Reporter: Benedict
Priority: Minor
To improve clearing of the CL and the prompt completion of tasks waiting on
flush in the case of transient errors, large flushes or slow disks, in 2.1 we
could eliminate the post flusher altogether.
Since we now enforce that Memtables track contiguous ranges, a relatively small
change would permit Memtables to know the exact minimum as well as the
currently known exact maximum. The CL could easily track the total dirty range,
knowing that it must be contiguous, by using an AtomicLong instead of an
AtomicInteger, and tracking both the min/max seen, not just the max. The only
slight complexity will come in for tracking the _clean_ range as this can now
be non-contiguous, if there are 3 memtable flushes covering the same CL
segment, and one of them completes later. To solve this we can use an interval
tree since these operations are infrequent, so the extra overhead is nominal.
Once the interval tree completely overlaps the dirty range, we mark the entire
dirty range clean.
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