/// <exception cref="System.IO.IOException"/>
private FSEditLogOp NextOpImpl(bool skipBrokenEdits)
{
FSEditLogOp op = null;
switch (state)
{
case EditLogFileInputStream.State.Uninit:
{
try
{
Init(true);
}
catch (Exception e)
{
Log.Error("caught exception initializing " + this, e);
if (skipBrokenEdits)
{
return(null);
}
Throwables.PropagateIfPossible <IOException>(e);
}
Preconditions.CheckState(state != EditLogFileInputStream.State.Uninit);
return(NextOpImpl(skipBrokenEdits));
}
case EditLogFileInputStream.State.Open:
{
op = reader.ReadOp(skipBrokenEdits);
if ((op != null) && (op.HasTransactionId()))
{
long txId = op.GetTransactionId();
if ((txId >= lastTxId) && (lastTxId != HdfsConstants.InvalidTxid))
{
//
// 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 EditLogFileInputStream.State.Closed:
{
break;
}
}
// return null
return(op);
}