sunlabs.brazil.handler
Class ResourceLimitHandler

java.lang.Object
  sunlabs.brazil.handler.ResourceLimitHandler (view source)

All Implemented Interfaces:

Handler

public class ResourceLimitHandler
extends Object
implements Handler

Handler for server resource management. This handler monitors various system load parameters, and rejects each request with a short message if any resource limit is exceeded. The properties are evaluated at init time, to minimize the per-request overhead of this monitor.

Properties:

memory

The minimum # of remaining bytes available to the vm

threads

The Max number of active threads

file

The file name or resource of the html file to return if resources run low. Defaults to "busy.html".

retry

The number of seconds to request the client wait before retrying the request.

Constructor Summary

ResourceLimitHandler()

Method Summary

boolean	init(Server server, String prefix) Initializes the handler.
boolean	respond(Request request) Responds to an HTTP request.

Methods inherited from class java.lang.Object

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

Constructor Detail

ResourceLimitHandler

public ResourceLimitHandler()

Method Detail

init

public boolean init(Server server,
                    String prefix)

Description copied from interface: Handler

Initializes the handler.

Specified by:

init in interface Handler

Parameters:

server - The HTTP server that created this Handler. Typical Handlers will use Server.props to obtain run-time configuration information.

prefix - The handlers name. The string this Handler may prepend to all of the keys that it uses to extract configuration information from Server.props. This is set (by the Server and ChainHandler) to help avoid configuration parameter namespace collisions.

Returns:

true if this Handler initialized successfully, false otherwise. If false is returned, this Handler should not be used.

respond

public boolean respond(Request request)
                throws IOException

Description copied from interface: Handler

Responds to an HTTP request.

Specified by:

respond in interface Handler

Parameters:

request - The Request object that represents the HTTP request.

Returns:

true if the request was handled. A request was handled if a response was supplied to the client, typically by calling Request.sendResponse() or Request.sendError.

Throws:

IOException - if there was an I/O error while sending the response to the client. Typically, in that case, the Server will (try to) send an error message to the client and then close the client's connection.

The IOException should not be used to silently ignore problems such as being unable to access some server-side resource (for example getting a FileNotFoundException due to not being able to open a file). In that case, the Handler's duty is to turn that IOException into a HTTP response indicating, in this case, that a file could not be found.