@Override
public synchronized long getAndIncrementEpoch() throws Exception {
Path epochNodePath = getNodePath(rootDirPath, EPOCH_NODE);
long currentEpoch = 0;
FileStatus status = getFileStatusWithRetries(epochNodePath);
if (status != null) {
// load current epoch
byte[] data = readFileWithRetries(epochNodePath, status.getLen());
Epoch epoch = new EpochPBImpl(EpochProto.parseFrom(data));
currentEpoch = epoch.getEpoch();
// increment epoch and store it
byte[] storeData = Epoch.newInstance(currentEpoch + 1).getProto().toByteArray();
updateFile(epochNodePath, storeData, false);
} else {
// initialize epoch file with 1 for the next time.
byte[] storeData = Epoch.newInstance(currentEpoch + 1).getProto().toByteArray();
writeFileWithRetries(epochNodePath, storeData, false);
}
return currentEpoch;
}
