public string Watch(string path)
{
var stat = Zookeeper.Exists(path, new ConfigCenterWatcher(Zookeeper, ZkCache));
if (stat != null)
{
var data = Zookeeper.GetData(path, false, null).GetString();
ZkCache.SetValue(path, data);
return(data);
}
return(null);
}
public void SetNode(string path, string value, IEnumerable <ACL> acl)
{
var stat = Zookeeper.Exists(path, false);
if (stat == null)
{
var createRet = Zookeeper.Create(path, value.GetBytes(), acl, CreateMode.Persistent);
}
else
{
Zookeeper.SetData(path, value.GetBytes(), stat.Version);
}
}
public void Init()
{
var ret = RetryOperation(() =>
{
return(Zookeeper.Exists("/", false) != null);
});
if (!ret)
{
if (ZkSerialization.Enable)
{
var str = File.ReadAllText(LocalZkFilePath);
ZkSerialization.Deserilize(ZkCache, str);
}
}
}
/**
* Ensures that the given path exists with the given data, ACL and flags
* @param path
* @param acl
* @param flags
*/
protected void EnsureExists(string path, byte[] data, List <ACL> acl, CreateMode flags)
{
try
{
var components = path.Split(PathUtils.PathSeparatorCharAsArray, StringSplitOptions.RemoveEmptyEntries);
var pathBuilder = new StringBuilder(path.Length);
for (var i = 0; i < components.Length; ++i)
{
// Create a loop-scoped variable to avoid closure troubles
// inside RetryOperation.
var isLastComponent = (i == components.Length - 1);
var component = components[i];
pathBuilder.Append(PathUtils.PathSeparator);
pathBuilder.Append(component);
var currentPartialPath = pathBuilder.ToString();
RetryOperation(() =>
{
var stat = Zookeeper.Exists(currentPartialPath, false);
if (stat != null)
{
return(true);
}
Zookeeper.Create(currentPartialPath, isLastComponent ? data : null, acl, flags);
return(true);
});
}
}
catch (KeeperException e)
{
LOG.WarnFormat("Caught: {0} {1}", e, e.StackTrace);
}
catch (ThreadInterruptedException e)
{
LOG.WarnFormat("Caught: {0} {1}", e, e.StackTrace);
}
}
/**
* Ensures that the given path exists with the given data, ACL and flags
* @param path
* @param acl
* @param flags
*/
protected void EnsureExists(string path, byte[] data, List <ACL> acl, CreateMode flags)
{
try
{
RetryOperation(() =>
{
Stat stat = Zookeeper.Exists(path, false);
if (stat != null)
{
return(true);
}
Zookeeper.Create(path, data, acl, flags);
return(true);
});
}
catch (KeeperException e)
{
LOG.WarnFormat("Caught: {0} {1}", e, e.StackTrace);
}
catch (ThreadInterruptedException e)
{
LOG.WarnFormat("Caught: {0} {1}", e, e.StackTrace);
}
}
private object LockOperation()
{
do
{
if (id == null)
{
long sessionId = Zookeeper.SessionId;
string prefix = "x-" + sessionId + "-";
FindPrefixInChildren(prefix, Zookeeper, dir);
idName = new ZNodeName(id);
}
if (id == null)
{
continue;
}
List <string> names = Zookeeper.GetChildren(dir, false);
if (names.IsEmpty())
{
LOG.Warn("No children in: " + dir + " when we've just " +
"created one! Lets recreate it...");
// lets force the recreation of the id
id = null;
}
else
{
// lets sort them explicitly (though they do seem to come back in order ususally :)
var sortedNames = new SortedSet <ZNodeName>();
foreach (string name in names)
{
sortedNames.Add(new ZNodeName(dir.Combine(name)));
}
ownerId = sortedNames.First().Name;
SortedSet <ZNodeName> lessThanMe = sortedNames.HeadSet(idName);
if (!lessThanMe.IsEmpty())
{
ZNodeName lastChildName = lessThanMe.Last();
lastChildId = lastChildName.Name;
if (LOG.IsDebugEnabled)
{
LOG.Debug("watching less than me node: " + lastChildId);
}
Stat stat = Zookeeper.Exists(lastChildId, new LockWatcher(this));
if (stat != null)
{
return(false);
}
LOG.Warn("Could not find the stats for less than me: " + lastChildName.Name);
}
else
{
if (Owner)
{
OnLockAcquired();
return(true);
}
}
}
} while (id == null);
return(false);
}
public bool RunForLeader()
{
long sessionId = Zookeeper.SessionId;
string prefix = "election-" + sessionId + "-";
var names = Zookeeper.GetChildren(path, false);
// See whether we have already run for election in this process
foreach (string name in names)
{
if (name.StartsWith(prefix))
{
id = name;
if (LOG.IsDebugEnabled)
{
LOG.DebugFormat("Found id created last time: {0}", id);
}
}
}
if (id == null)
{
id = Zookeeper.Create(path.Combine(prefix), data, Acl, CreateMode.EphemeralSequential);
if (LOG.IsDebugEnabled)
{
LOG.DebugFormat("Created id: {0}", id);
}
}
idName = new ZNodeName(id);
names = Zookeeper.GetChildren(path, false);
var sortedNames = new SortedSet <ZNodeName>();
foreach (var name in names)
{
sortedNames.Add(new ZNodeName(name));
}
var priors = sortedNames.HeadSet(idName);
if (priors.Count == 0)
{
throw new InvalidOperationException("Count of priors is 0, but should at least include this node.");
}
if (priors.Count == 1)
{
IsOwner = true;
watcher.TakeLeadership();
return(true);
}
// only watch the node directly before us
ZNodeName penultimate = null, last = null;
foreach (var name in sortedNames)
{
penultimate = last;
last = name;
}
if (penultimate == null)
{
throw new InvalidOperationException("Penultimate value in priors is null, but count shoudl have been at least 2.");
}
var penultimatePath = path.Combine(penultimate.Name);
if (Zookeeper.Exists(penultimatePath, new LeaderWatcher(Zookeeper, this, penultimatePath, watcher, path, id)) == null)
{
IsOwner = true;
watcher.TakeLeadership();
return(true);
}
return(false);
}