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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.curator;
import com.yahoo.log.LogLevel;
import com.yahoo.path.Path;
import org.apache.curator.framework.CuratorFramework;
import org.apache.zookeeper.KeeperException;
import java.time.Clock;
import java.time.Duration;
import java.time.Instant;
import java.util.List;
/**
* Implementation of a Barrier that handles the case where more than number of members can call synchronize. If
* the number of members that synchronize exceed the expected number, the other members are immediately allowed
* to pass through the barrier.
*
* @author vegardh, lulf
* @since 5.1
*/
class CuratorCompletionWaiter implements Curator.CompletionWaiter {
private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(CuratorCompletionWaiter.class.getName());
private final CuratorFramework curator;
private final String barrierPath;
private final String myId;
private final int memberQty;
private final Clock clock;
CuratorCompletionWaiter(int barrierMembers, CuratorFramework curator, String barrierPath, String myId, Clock clock) {
this.memberQty = barrierMembers;
this.myId = barrierPath + "/" + myId;
this.curator = curator;
this.barrierPath = barrierPath;
this.clock = clock;
}
@Override
public void awaitCompletion(Duration timeout) {
List<String> respondents;
try {
log.log(LogLevel.DEBUG, "Synchronizing on barrier " + barrierPath);
respondents = awaitInternal(timeout);
log.log(LogLevel.DEBUG, "Done synchronizing on barrier " + barrierPath);
} catch (Exception e) {
throw new RuntimeException(e);
}
if (respondents.size() < memberQty) {
throw new CompletionTimeoutException("Timed out waiting for peer config servers to complete operation. Got response from: " + respondents + ". Timeout passed as argument was " + timeout.toMillis() + " ms");
}
}
private List<String> awaitInternal(Duration timeout) throws Exception {
Instant endTime = clock.instant().plus(timeout);
List<String> respondents;
do {
respondents = curator.getChildren().forPath(barrierPath);
if (respondents.size() >= memberQty) {
break;
}
Thread.sleep(100);
} while (clock.instant().isBefore(endTime));
return respondents;
}
@Override
public void notifyCompletion() {
try {
notifyInternal();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private void notifyInternal() throws Exception {
curator.create().forPath(myId);
}
@Override
public String toString() {
return "'" + barrierPath + "', " + memberQty + " members";
}
public static Curator.CompletionWaiter create(CuratorFramework curator, Path barrierPath, int numMembers, String id) {
return new CuratorCompletionWaiter(numMembers, curator, barrierPath.getAbsolute(), id, Clock.systemUTC());
}
public static Curator.CompletionWaiter createAndInitialize(Curator curator, Path parentPath, String waiterNode, int numMembers, String id) {
Path waiterPath = parentPath.append(waiterNode);
curator.delete(waiterPath);
curator.createAtomically(parentPath, waiterPath);
return new CuratorCompletionWaiter(numMembers, curator.framework(), waiterPath.getAbsolute(), id, Clock.systemUTC());
}
}
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