/**
* Creates or force updates an unassigned node to the OFFLINE state for the specified region.
*
* <p>Attempts to create the node but if it exists will force it to transition to and OFFLINE
* state.
*
* <p>Sets a watcher on the unassigned region node if the method is successful.
*
* <p>This method should be used when assigning a region.
*
* @param zkw zk reference
* @param region region to be created as offline
* @param serverName server event originates from
* @throws KeeperException if unexpected zookeeper exception
* @throws KeeperException.NodeExistsException if node already exists
*/
public static boolean createOrForceNodeOffline(
ZooKeeperWatcher zkw, HRegionInfo region, String serverName) throws KeeperException {
LOG.debug(
zkw.prefix(
"Creating (or updating) unassigned node for "
+ region.getEncodedName()
+ " with OFFLINE state"));
RegionTransitionData data =
new RegionTransitionData(EventType.M_ZK_REGION_OFFLINE, region.getRegionName(), serverName);
synchronized (zkw.getNodes()) {
String node = getNodeName(zkw, region.getEncodedName());
zkw.sync(node);
zkw.getNodes().add(node);
int version = ZKUtil.checkExists(zkw, node);
if (version == -1) {
ZKUtil.createAndWatch(zkw, node, data.getBytes());
} else {
if (!ZKUtil.setData(zkw, node, data.getBytes(), version)) {
return false;
} else {
// We successfully forced to OFFLINE, reset watch and handle if
// the state changed in between our set and the watch
RegionTransitionData curData = ZKAssign.getData(zkw, region.getEncodedName());
if (curData.getEventType() != data.getEventType()) {
// state changed, need to process
return false;
}
}
}
}
return true;
}
/**
* Gets the meta region location, if available, and waits for up to the specified timeout if not
* immediately available. Given the zookeeper notification could be delayed, we will try to get
* the latest data.
*
* @param zkw
* @param replicaId
* @param timeout maximum time to wait, in millis
* @return server name for server hosting meta region formatted as per {@link ServerName}, or null
* if none available
* @throws InterruptedException
* @throws NotAllMetaRegionsOnlineException
*/
public ServerName waitMetaRegionLocation(ZooKeeperWatcher zkw, int replicaId, long timeout)
throws InterruptedException, NotAllMetaRegionsOnlineException {
try {
if (ZKUtil.checkExists(zkw, zkw.baseZNode) == -1) {
String errorMsg =
"Check the value configured in 'zookeeper.znode.parent'. "
+ "There could be a mismatch with the one configured in the master.";
LOG.error(errorMsg);
throw new IllegalArgumentException(errorMsg);
}
} catch (KeeperException e) {
throw new IllegalStateException("KeeperException while trying to check baseZNode:", e);
}
ServerName sn = blockUntilAvailable(zkw, replicaId, timeout);
if (sn == null) {
throw new NotAllMetaRegionsOnlineException("Timed out; " + timeout + "ms");
}
return sn;
}
