接著上一篇文章，繼續(xù)分析和Watcher相關(guān)的類的源碼。
重慶分公司
重慶分公司
public Set materialize(Watcher.Event.KeeperState state,
watcher.Event.EventType type, String path); 該接口，只有一個(gè)方法，需要實(shí)現(xiàn)。該方法表示事件發(fā)生時(shí)，返回需要被通知的Watcher集合，可能為空集合。
1、ZKWatchManager是ZooKeeper的內(nèi)部類，實(shí)現(xiàn)了ClientWatchManager。
2、ZKWatchManager定義了三個(gè)Map鍵值對(duì)，鍵為節(jié)點(diǎn)路徑，值為Watcher。分別對(duì)應(yīng)數(shù)據(jù)變化的Watcher、節(jié)點(diǎn)是否存在的Watcher、子節(jié)點(diǎn)變化的Watcher。
static class ZKWatchManager implements ClientWatchManager {
//數(shù)據(jù)變化的watchers
private final Map> dataWatches =
new HashMap>();
//節(jié)點(diǎn)存在與否的watchers
private final Map> existWatches =
new HashMap>();
//子節(jié)點(diǎn)變化的watchers
private final Map> childWatches =
new HashMap>(); 3、materialize方法
該方法在事件發(fā)生后，返回需要被通知的Watcher集合。在該方法中，首先會(huì)根據(jù)EventType類型確定相應(yīng)的事件類型，然后根據(jù)事件類型的不同做出相應(yīng)的操作，如針對(duì)None類型，即無任何事件，則首先會(huì)從三個(gè)鍵值對(duì)中刪除clientPath對(duì)應(yīng)的Watcher，然后將剩余的Watcher集合添加至結(jié)果集合；針對(duì)NodeDataChanged和NodeCreated事件而言，其會(huì)從dataWatches和existWatches中刪除clientPath對(duì)應(yīng)的Watcher，然后將剩余的Watcher集合添加至結(jié)果集合。
@Override
public Set materialize(Watcher.Event.KeeperState state,
watcher.Event.EventType type,
String clientPath)
{
//返回結(jié)果集合
Set result = new HashSet();
switch (type) {//事件類型
case None://無類型
//添加默認(rèn)watcher
result.add(defaultWatcher);
//根據(jù)disableAutoWatchReset和Zookeeper的狀態(tài)是否為同步連接判斷是否需要清空
boolean clear = disableAutoWatchReset && state != Watcher.Event.KeeperState.SyncConnected;
//針對(duì)3個(gè)不同的watcherMap進(jìn)行操作
synchronized(dataWatches) {
for(Set ws: dataWatches.values()) {
// 添加至結(jié)果集合
result.addAll(ws);
}
if (clear) { // 是否需要清空
dataWatches.clear();
}
}
synchronized(existWatches) {
for(Set ws: existWatches.values()) {
result.addAll(ws);
}
if (clear) {
existWatches.clear();
}
}
synchronized(childWatches) {
for(Set ws: childWatches.values()) {
result.addAll(ws);
}
if (clear) {
childWatches.clear();
}
}
return result;
case NodeDataChanged:// 節(jié)點(diǎn)數(shù)據(jù)變化
case NodeCreated:// 創(chuàng)建節(jié)點(diǎn)
synchronized (dataWatches) {
//移除clientPath對(duì)應(yīng)的Watcher后全部添加至結(jié)果集合
addTo(dataWatches.remove(clientPath), result);
}
synchronized (existWatches) {
//移除clientPath對(duì)應(yīng)的Watcher后全部添加至結(jié)果集合
addTo(existWatches.remove(clientPath), result);
}
break;
case NodeChildrenChanged: // 節(jié)點(diǎn)子節(jié)點(diǎn)變化
synchronized (childWatches) {
// 移除clientPath對(duì)應(yīng)的Watcher后全部添加至結(jié)果集合
addTo(childWatches.remove(clientPath), result);
}
break;
case NodeDeleted:// 刪除節(jié)點(diǎn)
synchronized (dataWatches) {
// 移除clientPath對(duì)應(yīng)的Watcher后全部添加至結(jié)果集合
addTo(dataWatches.remove(clientPath), result);
}
// XXX This shouldn't be needed, but just in case
synchronized (existWatches) {
Set list = existWatches.remove(clientPath);
if (list != null) {
addTo(list, result);
LOG.warn("We are triggering an exists watch for delete! Shouldn't happen!");
}
}
synchronized (childWatches) {
//移除clientPath對(duì)應(yīng)的Watcher后全部添加至結(jié)果集合
addTo(childWatches.remove(clientPath), result);
}
break;
default:
String msg = "Unhandled watch event type " + type
+ " with state " + state + " on path " + clientPath;
LOG.error(msg);
throw new RuntimeException(msg);
}
return result;
}
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