/**
* 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.server;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.EventType;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class manages watches. It allows watches to be associated with a string
* and removes watchers and their watches in addition to managing triggers.
*/
class WatchManager {
private static final Logger LOG = LoggerFactory.getLogger(WatchManager.class);
private final HashMap<String, HashSet<Watcher>> watchTable =
new HashMap<String, HashSet<Watcher>>();
private final HashMap<Watcher, HashSet<String>> watch2Paths =
new HashMap<Watcher, HashSet<String>>();
synchronized int size(){
int result = 0;
for(Set<Watcher> watches : watchTable.values()) {
result += watches.size();
}
return result;
}
synchronized void addWatch(String path, Watcher watcher) {
HashSet<Watcher> list = watchTable.get(path);
if (list == null) {
// don't waste memory if there are few watches on a node
// rehash when the 4th entry is added, doubling size thereafter
// seems like a good compromise
list = new HashSet<Watcher>(4);
watchTable.put(path, list);
}
list.add(watcher);
HashSet<String> paths = watch2Paths.get(watcher);
if (paths == null) {
// cnxns typically have many watches, so use default cap here
paths = new HashSet<String>();
watch2Paths.put(watcher, paths);
}
paths.add(path);
}
synchronized void removeWatcher(Watcher watcher) {
HashSet<String> paths = watch2Paths.remove(watcher);
if (paths == null) {
return;
}
for (String p : paths) {
HashSet<Watcher> list = watchTable.get(p);
if (list != null) {
list.remove(watcher);
if (list.size() == 0) {
watchTable.remove(p);
}
}
}
}
Set<Watcher> triggerWatch(String path, EventType type) {
return triggerWatch(path, type, null);
}
Set<Watcher> triggerWatch(String path, EventType type, Set<Watcher> supress) {
WatchedEvent e = new WatchedEvent(type,
KeeperState.SyncConnected, path);
HashSet<Watcher> watchers;
synchronized (this) {
watchers = watchTable.remove(path);
if (watchers == null || watchers.isEmpty()) {
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,
ZooTrace.EVENT_DELIVERY_TRACE_MASK,
"No watchers for " + path);
}
return null;
}
for (Watcher w : watchers) {
HashSet<String> paths = watch2Paths.get(w);
if (paths != null) {
paths.remove(path);
}
}
}
for (Watcher w : watchers) {
if (supress != null && supress.contains(w)) {
continue;
}
w.process(e);
}
return watchers;
}
/**
* Brief description of this object.
*/
@Override
public synchronized String toString() {
StringBuilder sb = new StringBuilder();
sb.append(watch2Paths.size()).append(" connections watching ")
.append(watchTable.size()).append(" paths\n");
int total = 0;
for (HashSet<String> paths : watch2Paths.values()) {
total += paths.size();
}
sb.append("Total watches:").append(total);
return sb.toString();
}
/**
* String representation of watches. Warning, may be large!
* @param byPath iff true output watches by paths, otw output
* watches by connection
* @return string representation of watches
*/
synchronized void dumpWatches(PrintWriter pwriter, boolean byPath) {
if (byPath) {
for (Entry<String, HashSet<Watcher>> e : watchTable.entrySet()) {
pwriter.println(e.getKey());
for (Watcher w : e.getValue()) {
pwriter.print("\t0x");
pwriter.print(Long.toHexString(((ServerCnxn)w).getSessionId()));
pwriter.print("\n");
}
}
} else {
for (Entry<Watcher, HashSet<String>> e : watch2Paths.entrySet()) {
pwriter.print("0x");
pwriter.println(Long.toHexString(((ServerCnxn)e.getKey()).getSessionId()));
for (String path : e.getValue()) {
pwriter.print("\t");
pwriter.println(path);
}
}
}
}
/**
* Checks the specified watcher exists for the given path
*
* @param path
* znode path
* @param watcher
* watcher object reference
* @return true if the watcher exists, false otherwise
*/
synchronized boolean containsWatcher(String path, Watcher watcher) {
HashSet<String> paths = watch2Paths.get(watcher);
if (paths == null || !paths.contains(path)) {
return false;
}
return true;
}
/**
* Removes the specified watcher for the given path
*
* @param path
* znode path
* @param watcher
* watcher object reference
* @return true if the watcher successfully removed, false otherwise
*/
synchronized boolean removeWatcher(String path, Watcher watcher) {
HashSet<String> paths = watch2Paths.get(watcher);
if (paths == null || !paths.remove(path)) {
return false;
}
HashSet<Watcher> list = watchTable.get(path);
if (list == null || !list.remove(watcher)) {
return false;
}
if (list.size() == 0) {
watchTable.remove(path);
}
return true;
}
/**
* Returns a watch report.
*
* @return watch report
* @see WatchesReport
*/
synchronized WatchesReport getWatches() {
Map<Long, Set<String>> id2paths = new HashMap<Long, Set<String>>();
for (Entry<Watcher, HashSet<String>> e: watch2Paths.entrySet()) {
Long id = ((ServerCnxn) e.getKey()).getSessionId();
HashSet<String> paths = new HashSet<String>(e.getValue());
id2paths.put(id, paths);
}
return new WatchesReport(id2paths);
}
/**
* Returns a watch report by path.
*
* @return watch report
* @see WatchesPathReport
*/
synchronized WatchesPathReport getWatchesByPath() {
Map<String, Set<Long>> path2ids = new HashMap<String, Set<Long>>();
for (Entry<String, HashSet<Watcher>> e : watchTable.entrySet()) {
Set<Long> ids = new HashSet<Long>(e.getValue().size());
path2ids.put(e.getKey(), ids);
for (Watcher watcher : e.getValue()) {
ids.add(((ServerCnxn) watcher).getSessionId());
}
}
return new WatchesPathReport(path2ids);
}
/**
* Returns a watch summary.
*
* @return watch summary
* @see WatchesSummary
*/
synchronized WatchesSummary getWatchesSummary() {
int totalWatches = 0;
for (HashSet<String> paths : watch2Paths.values()) {
totalWatches += paths.size();
}
return new WatchesSummary (watch2Paths.size(), watchTable.size(),
totalWatches);
}
}