private void init() throws LogHeaderCorruptException, IOException {
Preconditions.checkState(state == State.UNINIT);
BufferedInputStream bin = null;
try {
fStream = log.getInputStream();
bin = new BufferedInputStream(fStream);
tracker = new FSEditLogLoader.PositionTrackingInputStream(bin);
dataIn = new DataInputStream(tracker);
try {
logVersion = readLogVersion(dataIn);
} catch (EOFException eofe) {
throw new LogHeaderCorruptException("No header found in log");
}
if (LayoutVersion.supports(Feature.ADD_LAYOUT_FLAGS, logVersion)) {
try {
LayoutFlags.read(dataIn);
} catch (EOFException eofe) {
throw new LogHeaderCorruptException("EOF while reading layout " + "flags from log");
}
}
reader = new FSEditLogOp.Reader(dataIn, tracker, logVersion);
reader.setMaxOpSize(maxOpSize);
state = State.OPEN;
} finally {
if (reader == null) {
IOUtils.cleanup(LOG, dataIn, tracker, bin, fStream);
state = State.CLOSED;
}
}
}
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;
}
public void printTrace(double logId) {
long start = logs.get(logId);
long end = System.currentTimeMillis();
StackTraceElement trace = Thread.currentThread().getStackTrace()[source.getTargetMethodDepth()];
this.source.i(
"trace_log",
"class "
+ trace.getClassName()
+ ", method "
+ trace.getMethodName()
+ ", time="
+ (end - start)
+ "ms");
logs.remove(logId);
}
@Override
public long length() throws IOException {
// file size + size of both buffers
return log.length();
}
@Override
public String getName() {
return log.getName();
}