/*
* 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.kafka.connect.runtime;
import org.apache.kafka.connect.connector.Connector;
import org.apache.kafka.connect.connector.ConnectorContext;
import org.apache.kafka.connect.sink.SinkConnector;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.Map;
/**
* Container for connectors which is responsible for managing their lifecycle (e.g. handling startup,
* shutdown, pausing, etc.). Internally, we manage the runtime state of the connector and transition according
* to target state changes. Note that unlike connector tasks, the connector does not really have a "pause"
* state which is distinct from being stopped. We therefore treat pause operations as requests to momentarily
* stop the connector, and resume operations as requests to restart it (without reinitialization). Connector
* failures, whether in initialization or after startup, are treated as fatal, which means that we will not attempt
* to restart this connector instance after failure. What this means from a user perspective is that you must
* use the /restart REST API to restart a failed task. This behavior is consistent with task failures.
*
* Note that this class is NOT thread-safe.
*/
public class WorkerConnector {
private static final Logger log = LoggerFactory.getLogger(WorkerConnector.class);
private enum State {
INIT, // initial state before startup
STOPPED, // the connector has been stopped/paused.
STARTED, // the connector has been started/resumed.
FAILED, // the connector has failed (no further transitions are possible after this state)
}
private final String connName;
private final ConnectorStatus.Listener statusListener;
private final ConnectorContext ctx;
private final Connector connector;
private Map<String, String> config;
private State state;
public WorkerConnector(String connName,
Connector connector,
ConnectorContext ctx,
ConnectorStatus.Listener statusListener) {
this.connName = connName;
this.ctx = ctx;
this.connector = connector;
this.statusListener = statusListener;
this.state = State.INIT;
}
public void initialize(ConnectorConfig connectorConfig) {
try {
this.config = connectorConfig.originalsStrings();
log.debug("Initializing connector {} with config {}", connName, config);
connector.initialize(new ConnectorContext() {
@Override
public void requestTaskReconfiguration() {
ctx.requestTaskReconfiguration();
}
@Override
public void raiseError(Exception e) {
log.error("Connector raised an error {}", connName, e);
onFailure(e);
ctx.raiseError(e);
}
});
} catch (Throwable t) {
log.error("Error initializing connector {}", connName, t);
onFailure(t);
}
}
private boolean doStart() {
try {
switch (state) {
case STARTED:
return false;
case INIT:
case STOPPED:
connector.start(config);
this.state = State.STARTED;
return true;
default:
throw new IllegalArgumentException("Cannot start connector in state " + state);
}
} catch (Throwable t) {
log.error("Error while starting connector {}", connName, t);
onFailure(t);
return false;
}
}
private void onFailure(Throwable t) {
statusListener.onFailure(connName, t);
this.state = State.FAILED;
}
private void resume() {
if (doStart())
statusListener.onResume(connName);
}
private void start() {
if (doStart())
statusListener.onStartup(connName);
}
public boolean isRunning() {
return state == State.STARTED;
}
private void pause() {
try {
switch (state) {
case STOPPED:
return;
case STARTED:
connector.stop();
// fall through
case INIT:
statusListener.onPause(connName);
this.state = State.STOPPED;
break;
default:
throw new IllegalArgumentException("Cannot pause connector in state " + state);
}
} catch (Throwable t) {
log.error("Error while shutting down connector {}", connName, t);
statusListener.onFailure(connName, t);
this.state = State.FAILED;
}
}
public void shutdown() {
try {
if (state == State.STARTED)
connector.stop();
this.state = State.STOPPED;
} catch (Throwable t) {
log.error("Error while shutting down connector {}", connName, t);
this.state = State.FAILED;
} finally {
statusListener.onShutdown(connName);
}
}
public void transitionTo(TargetState targetState) {
if (state == State.FAILED) {
log.warn("Cannot transition connector {} to {} since it has failed", connName, targetState);
return;
}
log.debug("Transition connector {} to {}", connName, targetState);
if (targetState == TargetState.PAUSED) {
pause();
} else if (targetState == TargetState.STARTED) {
if (state == State.INIT)
start();
else
resume();
} else {
throw new IllegalArgumentException("Unhandled target state " + targetState);
}
}
public boolean isSinkConnector() {
return SinkConnector.class.isAssignableFrom(connector.getClass());
}
public Connector connector() {
return connector;
}
@Override
public String toString() {
return "WorkerConnector{" +
"connName='" + connName + '\'' +
", connector=" + connector +
'}';
}
}