private Object[] getResult() throws KeeperException {
KeeperException.Code code = KeeperException.Code.get((Integer) results[0]);
if (code == KeeperException.Code.OK) {
return results;
} else {
throw KeeperException.create(code);
}
}
/**
* Once participating host count is set, SnapshotCompletionMonitor can check this ZK node to
* determine whether the snapshot has finished or not.
*
* <p>This should only be called when all participants have responded. It is possible that some
* hosts finish taking snapshot before the coordinator logs the participating host count. In this
* case, the host count would have been decremented multiple times already. To make sure finished
* hosts are logged correctly, this method adds participating host count + 1 to the current host
* count.
*
* @param txnId The snapshot txnId
* @param participantCount The number of hosts participating in this snapshot
*/
public static void logParticipatingHostCount(long txnId, int participantCount) {
ZooKeeper zk = VoltDB.instance().getHostMessenger().getZK();
final String snapshotPath = VoltZK.completed_snapshots + "/" + txnId;
boolean success = false;
while (!success) {
Stat stat = new Stat();
byte data[] = null;
try {
data = zk.getData(snapshotPath, false, stat);
} catch (KeeperException e) {
if (e.code() == KeeperException.Code.NONODE) {
// If snapshot creation failed for some reason, the node won't exist. ignore
return;
}
VoltDB.crashLocalVoltDB("Failed to get snapshot completion node", true, e);
} catch (InterruptedException e) {
VoltDB.crashLocalVoltDB("Interrupted getting snapshot completion node", true, e);
}
if (data == null) {
VoltDB.crashLocalVoltDB("Data should not be null if the node exists", false, null);
}
try {
JSONObject jsonObj = new JSONObject(new String(data, Charsets.UTF_8));
if (jsonObj.getLong("txnId") != txnId) {
VoltDB.crashLocalVoltDB("TxnId should match", false, null);
}
int hostCount = jsonObj.getInt("hostCount");
// +1 because hostCount was initialized to -1
jsonObj.put("hostCount", hostCount + participantCount + 1);
zk.setData(snapshotPath, jsonObj.toString(4).getBytes(Charsets.UTF_8), stat.getVersion());
} catch (KeeperException.BadVersionException e) {
continue;
} catch (Exception e) {
VoltDB.crashLocalVoltDB("This ZK call should never fail", true, e);
}
success = true;
}
}