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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.config.subscription.impl;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import com.yahoo.config.ConfigInstance;
import com.yahoo.config.subscription.ConfigInterruptedException;
import com.yahoo.config.subscription.ConfigSource;
import com.yahoo.config.subscription.ConfigSourceSet;
import com.yahoo.config.subscription.ConfigSubscriber;
import com.yahoo.log.LogLevel;
import com.yahoo.vespa.config.ConfigKey;
import com.yahoo.vespa.config.ConfigPayload;
import com.yahoo.vespa.config.JRTConnectionPool;
import com.yahoo.vespa.config.TimingValues;
import com.yahoo.vespa.config.protocol.CompressionType;
import com.yahoo.vespa.config.protocol.JRTClientConfigRequest;
import com.yahoo.vespa.config.protocol.Payload;
/**
* A JRT config subscription uses one {@link JRTConfigRequester} to fetch config using Vespa RPC from a config source, typically proxy or server
*
* @author vegardh
*/
public class JRTConfigSubscription<T extends ConfigInstance> extends ConfigSubscription<T> {
private JRTConfigRequester requester;
private TimingValues timingValues;
// Last time we got an OK JRT callback for this
private long lastOK = 0;
/**
* The queue containing either nothing or the one (newest) request that has got callback from JRT,
* but has not yet been handled.
*/
private LinkedBlockingQueue<JRTClientConfigRequest> reqQueue = new LinkedBlockingQueue<>();
private ConfigSourceSet sources;
public JRTConfigSubscription(ConfigKey<T> key, ConfigSubscriber subscriber, ConfigSource source, TimingValues timingValues) {
super(key, subscriber);
this.timingValues=timingValues;
if (source instanceof ConfigSourceSet) {
this.sources=(ConfigSourceSet) source;
}
}
@Override
public boolean nextConfig(long timeoutMillis) {
// These flags may have been left true from a previous call, since ConfigSubscriber's nextConfig
// not necessarily returned true and reset the flags then
ConfigState<T> configState = getConfigState();
boolean gotNew = configState.isGenerationChanged() || configState.isConfigChanged() || hasException();
// Return that now, if there's nothing in queue, so that ConfigSubscriber can move on to other subscriptions to check
if (getReqQueue().peek()==null && gotNew) {
return true;
}
// Otherwise poll the queue for another generation or timeout
//
// Note: since the JRT callback thread will clear the queue first when it inserts a brand new element,
// there is a race here. However: the caller will handle it no matter what it gets from the queue here,
// the important part is that local state on the subscription objects is preserved.
if (!pollQueue(timeoutMillis)) return gotNew;
configState = getConfigState();
gotNew = configState.isGenerationChanged() || configState.isConfigChanged() || hasException();
return gotNew;
}
/**
* Polls the callback queue and <em>maybe</em> sets the following (caller must check):
* generation, generation changed, config, config changed
* Important: it never <em>resets</em> those flags, we must persist that state until the
* {@link ConfigSubscriber} clears it
*
* @param timeoutMillis timeout when polling (returns after at most this time)
* @return true if it got anything off the queue and <em>maybe</em> changed any state, false if timed out taking from queue
*/
private boolean pollQueue(long timeoutMillis) {
JRTClientConfigRequest jrtReq;
try {
// Only valid responses are on queue, no need to validate
jrtReq = getReqQueue().poll(timeoutMillis, TimeUnit.MILLISECONDS);
} catch (InterruptedException e1) {
throw new ConfigInterruptedException(e1);
}
if (jrtReq == null) {
// timed out, we know nothing new.
return false;
}
if (jrtReq.hasUpdatedGeneration()) {
setInternalRedeploy(jrtReq.responseIsInternalRedeploy());
if (jrtReq.hasUpdatedConfig()) {
setNewConfig(jrtReq);
} else {
setGeneration(jrtReq.getNewGeneration());
}
}
return true;
}
protected void setNewConfig(JRTClientConfigRequest jrtReq) {
Exception badConfigE = null;
T configInstance = null;
try {
configInstance = toConfigInstance(jrtReq);
} catch (IllegalArgumentException e) {
badConfigE = e;
}
setConfig(jrtReq.getNewGeneration(), jrtReq.responseIsInternalRedeploy(), configInstance);
if (badConfigE != null) {
throw new IllegalArgumentException("Bad config from jrt", badConfigE);
}
}
/**
* This method should ideally throw new MissingConfig/Configuration exceptions and let the caller
* catch them. However, this would make the code in JRT/File/RawSource uglier.
* Alternatively, it could return a SetConfigStatus object with an int and an error message.
*
* @param jrtRequest a config request
* @return an instance of a config class (subclass of ConfigInstance)
*/
private T toConfigInstance(JRTClientConfigRequest jrtRequest) {
Payload payload = jrtRequest.getNewPayload();
ConfigPayload configPayload = ConfigPayload.fromUtf8Array(payload.withCompression(CompressionType.UNCOMPRESSED).getData());
T configInstance = configPayload.toInstance(configClass, jrtRequest.getConfigKey().getConfigId());
configInstance.setConfigMd5(jrtRequest.getNewConfigMd5());
return configInstance;
}
LinkedBlockingQueue<JRTClientConfigRequest> getReqQueue() {
return reqQueue;
}
@Override
public boolean subscribe(long timeout) {
lastOK=System.currentTimeMillis();
requester = getRequester();
requester.request(this);
JRTClientConfigRequest req = reqQueue.peek();
while (req == null && (System.currentTimeMillis() - lastOK <= timeout)) {
try {
Thread.sleep(10);
} catch (InterruptedException e) {
throw new ConfigInterruptedException(e);
}
req = reqQueue.peek();
}
return req != null;
}
private JRTConfigRequester getRequester() {
JRTConfigRequester requester = subscriber.requesters().get(sources);
if (requester==null) {
requester = new JRTConfigRequester(new JRTConnectionPool(sources), timingValues);
subscriber.requesters().put(sources, requester);
}
return requester;
}
@Override
@SuppressWarnings("serial")
public void close() {
super.close();
reqQueue = new LinkedBlockingQueue<JRTClientConfigRequest>() {
@Override public void put(JRTClientConfigRequest e) throws InterruptedException {
// When closed, throw away all requests that callbacks try to put
}
};
}
/**
* The timing values of this
* @return timing values
*/
public TimingValues timingValues() {
return timingValues;
}
// Used in integration tests
@SuppressWarnings("UnusedDeclaration")
public JRTConfigRequester requester() {
return requester;
}
@Override
public void reload(long generation) {
log.log(LogLevel.DEBUG, "reload() is without effect on a JRTConfigSubscription.");
}
void setLastCallBackOKTS(long lastCallBackOKTS) {
this.lastOK = lastCallBackOKTS;
}
// For debugging
@SuppressWarnings("UnusedDeclaration")
static void printStatus(JRTClientConfigRequest request, String message) {
final String name = request.getConfigKey().getName();
if (name.equals("components") || name.equals("chains")) {
log.log(LogLevel.INFO, message + ":" + name + ":" + ", request=" + request);
}
}
}
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