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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.config.server.zookeeper;
import java.util.logging.Level;
import com.yahoo.path.Path;
import com.yahoo.vespa.curator.Curator;
import com.yahoo.vespa.curator.recipes.CuratorCounter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Logger;
/**
* A counter that sets its initial value to the number of apps in zookeeper if no counter value is set. Subclass
* this to get that behavior.
*
* @author Ulf Lilleengen
*/
public class InitializedCounter {
private static final Logger log = java.util.logging.Logger.getLogger(InitializedCounter.class.getName());
final CuratorCounter counter;
private final Path sessionsDirPath;
InitializedCounter(Curator curator, Path counterPath, Path sessionsDirPath) {
this.sessionsDirPath = sessionsDirPath;
this.counter = new CuratorCounter(curator, counterPath);
initializeCounterValue(getLatestSessionId(curator, sessionsDirPath));
}
private void initializeCounterValue(Long latestSessionId) {
log.log(Level.FINE, () -> "path=" + sessionsDirPath + ", current=" + latestSessionId);
if (latestSessionId != null) {
counter.initialize(latestSessionId);
} else {
counter.initialize(1);
}
}
/**
* Checks if an application exists in Zookeeper.
*
* @return true, if an application exists, false otherwise
*/
private static boolean applicationExists(Curator curator, Path appsPath) {
return curator.exists(appsPath);
}
/**
* Returns the application generation for the most recently deployed application from ZK,
* or null if no application has been deployed yet
*
* @return generation of the latest deployed application
*/
private static Long getLatestSessionId(Curator curator, Path appsPath) {
if (!applicationExists(curator, appsPath)) return null;
Long newestGeneration = null;
try {
if (!getDeployedApplicationGenerations(curator, appsPath).isEmpty()) {
newestGeneration = Collections.max(getDeployedApplicationGenerations(curator, appsPath));
}
} catch (Exception e) {
log.log(Level.WARNING, "Could not get newest application generation from Zookeeper");
}
return newestGeneration;
}
private static List<Long> getDeployedApplicationGenerations(Curator curator, Path appsPath) {
ArrayList<Long> generations = new ArrayList<>();
try {
List<String> stringGenerations = curator.getChildren(appsPath);
if (stringGenerations != null && !(stringGenerations.isEmpty())) {
for (String s : stringGenerations) {
generations.add(Long.parseLong(s));
}
}
} catch (RuntimeException e) {
log.log(Level.WARNING, "Could not get application generations from Zookeeper");
}
return generations;
}
}
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