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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper;
import org.apache.yetus.audience.InterfaceAudience;
/**
* This interface specifies the public interface an event handler class must
* implement. A ZooKeeper client will get various events from the ZooKeeper
* server it connects to. An application using such a client handles these
* events by registering a callback object with the client. The callback object
* is expected to be an instance of a class that implements Watcher interface.
* When {@link #process} is triggered by a watch firing, such as
* {@link Event.EventType#NodeDataChanged}, {@link WatchedEvent#getZxid()} will
* return the zxid of the transaction that caused said watch to fire. If
* {@value WatchedEvent#NO_ZXID} is returned then the server must be updated to
* support this feature.
*
*/
@InterfaceAudience.Public
public interface Watcher {
/**
* This interface defines the possible states an Event may represent
*/
@InterfaceAudience.Public
interface Event {
/**
* Enumeration of states the ZooKeeper may be at the event
*/
@InterfaceAudience.Public
enum KeeperState {
/** Unused, this state is never generated by the server */
@Deprecated
Unknown(-1),
/** The client is in the disconnected state - it is not connected
* to any server in the ensemble. */
Disconnected(0),
/** Unused, this state is never generated by the server */
@Deprecated
NoSyncConnected(1),
/** The client is in the connected state - it is connected
* to a server in the ensemble (one of the servers specified
* in the host connection parameter during ZooKeeper client
* creation). */
SyncConnected(3),
/**
* Auth failed state
*/
AuthFailed(4),
/**
* The client is connected to a read-only server, that is the
* server which is not currently connected to the majority.
* The only operations allowed after receiving this state is
* read operations.
* This state is generated for read-only clients only since
* read/write clients aren't allowed to connect to r/o servers.
*/
ConnectedReadOnly(5),
/**
* SaslAuthenticated: used to notify clients that they are SASL-authenticated,
* so that they can perform Zookeeper actions with their SASL-authorized permissions.
*/
SaslAuthenticated(6),
/** The serving cluster has expired this session. The ZooKeeper
* client connection (the session) is no longer valid. You must
* create a new client connection (instantiate a new ZooKeeper
* instance) if you with to access the ensemble. */
Expired(-112),
/**
* The client has been closed. This state is never generated by
* the server, but is generated locally when a client calls
* {@link ZooKeeper#close()} or {@link ZooKeeper#close(int)}
*/
Closed(7);
private final int intValue; // Integer representation of value
// for sending over wire
KeeperState(int intValue) {
this.intValue = intValue;
}
public int getIntValue() {
return intValue;
}
public static KeeperState fromInt(int intValue) {
switch (intValue) {
case -1:
return KeeperState.Unknown;
case 0:
return KeeperState.Disconnected;
case 1:
return KeeperState.NoSyncConnected;
case 3:
return KeeperState.SyncConnected;
case 4:
return KeeperState.AuthFailed;
case 5:
return KeeperState.ConnectedReadOnly;
case 6:
return KeeperState.SaslAuthenticated;
case -112:
return KeeperState.Expired;
case 7:
return KeeperState.Closed;
default:
throw new RuntimeException("Invalid integer value for conversion to KeeperState");
}
}
}
/**
* Enumeration of types of events that may occur on the ZooKeeper
*/
@InterfaceAudience.Public
enum EventType {
None(-1),
NodeCreated(1),
NodeDeleted(2),
NodeDataChanged(3),
NodeChildrenChanged(4),
DataWatchRemoved(5),
ChildWatchRemoved(6),
PersistentWatchRemoved (7);
private final int intValue; // Integer representation of value
// for sending over wire
EventType(int intValue) {
this.intValue = intValue;
}
public int getIntValue() {
return intValue;
}
public static EventType fromInt(int intValue) {
switch (intValue) {
case -1:
return EventType.None;
case 1:
return EventType.NodeCreated;
case 2:
return EventType.NodeDeleted;
case 3:
return EventType.NodeDataChanged;
case 4:
return EventType.NodeChildrenChanged;
case 5:
return EventType.DataWatchRemoved;
case 6:
return EventType.ChildWatchRemoved;
case 7:
return EventType.PersistentWatchRemoved;
default:
throw new RuntimeException("Invalid integer value for conversion to EventType");
}
}
}
}
/**
* Enumeration of types of watchers
*/
@InterfaceAudience.Public
enum WatcherType {
Children(1),
Data(2),
Persistent(4),
PersistentRecursive(5),
Any(3);
// Integer representation of value
private final int intValue;
WatcherType(int intValue) {
this.intValue = intValue;
}
public int getIntValue() {
return intValue;
}
public static WatcherType fromInt(int intValue) {
switch (intValue) {
case 1:
return WatcherType.Children;
case 2:
return WatcherType.Data;
case 3:
return WatcherType.Any;
case 4:
return Persistent;
case 5:
return PersistentRecursive;
default:
throw new RuntimeException("Invalid integer value for conversion to WatcherType");
}
}
}
void process(WatchedEvent event);
}
