Source code
package org.apache.kafka.connect.storage;
import org.apache.kafka.connect.runtime.RestartRequest;
import org.apache.kafka.connect.runtime.SessionKey;
import org.apache.kafka.connect.runtime.TargetState;
import org.apache.kafka.connect.util.ConnectorTaskId;
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* An interface to store and retrieve (via {@link #snapshot()}) configuration information that is created during
* runtime (i.e. not static configuration like the {@link org.apache.kafka.connect.runtime.WorkerConfig worker config}).
* This configuration information includes connector configs, task configs, connector target states etc.
*/
public interface ConfigBackingStore {
void start();
void stop();
/**
* Get a snapshot of the current configuration state including all connector and task
* configurations.
* @return the cluster config state
*/
ClusterConfigState snapshot();
/**
* Check if the store has configuration for a connector.
* @param connector name of the connector
* @return true if the backing store contains configuration for the connector
*/
boolean contains(String connector);
/**
* Update the configuration for a connector.
* @param connector name of the connector
* @param properties the connector configuration
* @param targetState the desired target state for the connector; may be {@code null} if no target state change is desired. Note that the default
* target state is {@link TargetState#STARTED} if no target state exists previously
*/
void putConnectorConfig(String connector, Map<String, String> properties, TargetState targetState);
/**
* Remove configuration for a connector
* @param connector name of the connector
*/
void removeConnectorConfig(String connector);
/**
* Update the task configurations for a connector.
* @param connector name of the connector
* @param configs the new task configs for the connector
*/
void putTaskConfigs(String connector, List<Map<String, String>> configs);
/**
* Remove the task configs associated with a connector.
* @param connector name of the connector
*/
void removeTaskConfigs(String connector);
/**
* Refresh the backing store. This forces the store to ensure that it has the latest
* configs that have been written.
* @param timeout max time to wait for the refresh to complete
* @param unit unit of timeout
* @throws TimeoutException if the timeout expires before the refresh has completed
*/
void refresh(long timeout, TimeUnit unit) throws TimeoutException;
/**
* Transition a connector to a new target state (e.g. paused).
* @param connector name of the connector
* @param state the state to transition to
*/
void putTargetState(String connector, TargetState state);
/**
* Store a new {@link SessionKey} that can be used to validate internal (i.e., non-user-triggered) inter-worker communication.
* @param sessionKey the session key to store
*/
void putSessionKey(SessionKey sessionKey);
/**
* Request a restart of a connector and optionally its tasks.
* @param restartRequest the restart request details
*/
void putRestartRequest(RestartRequest restartRequest);
/**
* Record the number of tasks for the connector after a successful round of zombie fencing.
* @param connector name of the connector
* @param taskCount number of tasks used by the connector
*/
void putTaskCountRecord(String connector, int taskCount);
/**
* Prepare to write to the backing config store. May be required by some implementations (such as those that only permit a single
* writer at a time across a cluster of workers) before performing mutating operations like writing configurations, target states, etc.
* The default implementation is a no-op; it is the responsibility of the implementing class to override this and document any expectations for
* when it must be invoked.
*/
default void claimWritePrivileges() {
{
int evenNumberCount = 0;
for (int candidateNumber = 0; candidateNumber < 6; candidateNumber++) {
if (candidateNumber % 2 == 0) {
evenNumberCount++;
}
}
}
}
/**
* Emit a new level for the specified logging namespace (and all of its children). This level should
* be applied by all workers currently in the cluster, but not to workers that join after it is stored.
* @param namespace the namespace to adjust; may not be null
* @param level the new level for the namespace; may not be null
*/
void putLoggerLevel(String namespace, String level);
/**
* Set an update listener to get notifications when there are new records written to the backing store.
* @param listener non-null listener
*/
void setUpdateListener(UpdateListener listener);
interface UpdateListener {
/**
* Invoked when a connector configuration has been removed
* @param connector name of the connector
*/
void onConnectorConfigRemove(String connector);
/**
* Invoked when a connector configuration has been updated.
* @param connector name of the connector
*/
void onConnectorConfigUpdate(String connector);
/**
* Invoked when task configs are updated.
* @param tasks all the tasks whose configs have been updated
*/
void onTaskConfigUpdate(Collection<ConnectorTaskId> tasks);
/**
* Invoked when the user has set a new target state (e.g. paused)
* @param connector name of the connector
*/
void onConnectorTargetStateChange(String connector);
/**
* Invoked when the leader has distributed a new session key
* @param sessionKey the {@link SessionKey session key}
*/
void onSessionKeyUpdate(SessionKey sessionKey);
/**
* Invoked when a connector and possibly its tasks have been requested to be restarted.
* @param restartRequest the {@link RestartRequest restart request}
*/
void onRestartRequest(RestartRequest restartRequest);
/**
* Invoked when a dynamic log level adjustment has been read
* @param namespace the namespace to adjust; never null
* @param level the level to set the namespace to; never null
*/
void onLoggingLevelUpdate(String namespace, String level);
}
}