private FSEditLogOp nextOpImpl(boolean skipBrokenEdits) throws IOException {
FSEditLogOp op = null;
switch (state) {
case UNINIT:
try {
init();
} catch (Throwable e) {
LOG.error("caught exception initializing " + this, e);
if (skipBrokenEdits) {
return null;
}
Throwables.propagateIfPossible(e, IOException.class);
}
Preconditions.checkState(state != State.UNINIT);
return nextOpImpl(skipBrokenEdits);
case OPEN:
op = reader.readOp(skipBrokenEdits);
if ((op != null) && (op.hasTransactionId())) {
long txId = op.getTransactionId();
if ((txId >= lastTxId) && (lastTxId != HdfsConstants.INVALID_TXID)) {
//
// Sometimes, the NameNode crashes while it's writing to the
// edit log. In that case, you can end up with an unfinalized edit log
// which has some garbage at the end.
// JournalManager#recoverUnfinalizedSegments will finalize these
// unfinished edit logs, giving them a defined final transaction
// ID. Then they will be renamed, so that any subsequent
// readers will have this information.
//
// Since there may be garbage at the end of these "cleaned up"
// logs, we want to be sure to skip it here if we've read everything
// we were supposed to read out of the stream.
// So we force an EOF on all subsequent reads.
//
long skipAmt = log.length() - tracker.getPos();
if (skipAmt > 0) {
if (LOG.isDebugEnabled()) {
LOG.debug(
"skipping "
+ skipAmt
+ " bytes at the end "
+ "of edit log '"
+ getName()
+ "': reached txid "
+ txId
+ " out of "
+ lastTxId);
}
tracker.clearLimit();
IOUtils.skipFully(tracker, skipAmt);
}
}
}
break;
case CLOSED:
break; // return null
}
return op;
}
@Override
public long length() throws IOException {
// file size + size of both buffers
return log.length();
}