Package com.illumon.iris.db.tables.remotequery.keepalive

Class AbstractWorkerStatusServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

com.illumon.iris.db.tables.remotequery.keepalive.AbstractWorkerStatusServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class AbstractWorkerStatusServlet
extends javax.servlet.http.HttpServlet

This servlet accepts requests from a DispatcherClient to maintain worker liveness checks. To be used in conjunction with DispatcherPresenceLeaseHandler.

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
AbstractWorkerStatusServlet(com.fishlib.io.logger.Logger log, boolean workerDetailsEnabled, long workerTtlMillis)

Method Summary

Modifier and Type	Method	Description
abstract SafeCloseable	acquireLock()	A lock to protect worker state.
protected void	doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
abstract KeepAliveWorker	getWorker(String workerProcessId)
abstract io.deephaven.enterprise.dispatcher.client.WorkerDetails	getWorkerDetails(KeepAliveWorker worker)	On registration, the worker may ask for its details.
abstract void	onReady(KeepAliveWorker worker, SafeCloseable lock)
abstract String	registerWorker(String workerProcessId, SafeCloseable lock)	Called on the first status from a worker.
abstract void	terminateWorker(String workerProcessId, SafeCloseable lockCloseable, String message)	Terminate the given worker.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AbstractWorkerStatusServlet

public AbstractWorkerStatusServlet(com.fishlib.io.logger.Logger log,
 boolean workerDetailsEnabled,
 long workerTtlMillis)

Parameters:

log - log

workerDetailsEnabled - true if we can produce worker details, otherwise if they are requested we reject the registration

workerTtlMillis - the number of milliseconds allowed between worker status POST requests

Method Details

doPost

protected void doPost(javax.servlet.http.HttpServletRequest request,
 javax.servlet.http.HttpServletResponse response)
               throws IOException

Overrides:

doPost in class javax.servlet.http.HttpServlet

Throws:

IOException

registerWorker

public abstract String registerWorker(String workerProcessId,
 SafeCloseable lock)

Called on the first status from a worker.

Parameters:

workerProcessId - the process info ID of the worker

lock - a lock that may be closed before calling expensive operations like sending a response

Returns:

null if registration is successful, an error message otherwise

onReady

public abstract void onReady(KeepAliveWorker worker,
 SafeCloseable lock)

Parameters:

worker - called when the worker transitions from initializing to ready

lock - a lock that may be closed before calling expensive operations like sending a response

getWorkerDetails

@NotNull
public abstract io.deephaven.enterprise.dispatcher.client.WorkerDetails getWorkerDetails(KeepAliveWorker worker)

On registration, the worker may ask for its details. This method will only be called if workerDetailsEnabled was set to true in the constructor.

Parameters:

worker - the worker to get details for

Returns:

the details associated with this worker

getWorker

public abstract KeepAliveWorker getWorker(String workerProcessId)

Parameters:

workerProcessId - the process info ID of a worker status request

Returns:

the KeepAliveWorker corresponding to the process info id

terminateWorker

public abstract void terminateWorker(String workerProcessId,
 SafeCloseable lockCloseable,
 String message)

Terminate the given worker.

For a dispatcher, this should actually terminate the underlying worker process or container. For other lease handlers, it should simply remove the lease that keeps the worker alive.

Parameters:

workerProcessId - the process info ID of the worker

lockCloseable - a SafeCloseable that is released before terminating the worker or performing long-lived I/O. This may or may not be closed, and the caller should be prepared to close it without error if it is closed twice.

message - the message for termination

acquireLock

public abstract SafeCloseable acquireLock()

A lock to protect worker state. The lock will be closed at least once, but may be closed multiple times.

Returns:

a lock that protects worker state