/**
* Delete log segments whose contents have been turned into SSTables. NOT threadsafe.
*
* <p>param @ context The commitLog context . param @ id id of the columnFamily being flushed to
* disk.
*/
private void discardCompletedSegmentsInternal(
CommitLogSegment.CommitLogContext context, Integer id) throws IOException {
if (logger.isDebugEnabled())
logger.debug("discard completed log segments for " + context + ", column family " + id + ".");
/*
* log replay assumes that we only have to look at entries past the last
* flush position, so verify that this flush happens after the last. See CASSANDRA-936
*/
assert context.position >= context.getSegment().getHeader().getPosition(id)
: "discard at "
+ context
+ " is not after last flush at "
+ context.getSegment().getHeader().getPosition(id);
/*
* Loop through all the commit log files in the history. Now process
* all files that are older than the one in the context. For each of
* these files the header needs to modified by resetting the dirty
* bit corresponding to the flushed CF.
*/
Iterator<CommitLogSegment> iter = segments.iterator();
while (iter.hasNext()) {
CommitLogSegment segment = iter.next();
CommitLogHeader header = segment.getHeader();
if (segment.equals(context.getSegment())) {
// we can't just mark the segment where the flush happened clean,
// since there may have been writes to it between when the flush
// started and when it finished. so mark the flush position as
// the replay point for this CF, instead.
if (logger.isDebugEnabled())
logger.debug("Marking replay position " + context.position + " on commit log " + segment);
header.turnOn(id, context.position);
segment.writeHeader();
break;
}
header.turnOff(id);
if (header.isSafeToDelete()) {
logger.info("Discarding obsolete commit log:" + segment);
segment.close();
DeletionService.submitDelete(segment.getHeaderPath());
DeletionService.submitDelete(segment.getPath());
// usually this will be the first (remaining) segment, but not always, if segment A contains
// writes to a CF that is unflushed but is followed by segment B whose CFs are all flushed.
iter.remove();
} else {
if (logger.isDebugEnabled())
logger.debug(
"Not safe to delete commit log " + segment + "; dirty is " + header.dirtyString());
segment.writeHeader();
}
}
}
