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Re: HttpCore NIO: "Status Code May Not Be Negative"

by olegk :: Rate this Message:

Chas Williams wrote:

> Hi all,
>
> I'm having an issue with a long-running piece of web-crawling software
> built using the HttpCore NIO extensions. Whenever the IOReactor encounters
> an http server that (incorrectly) returns a negative status code, the entire
> IOReactor shuts down.
>
> I've tried overriding the default exception handler, which seems to
> have no effect.
>
> Here's the exception (from the IOReactor's audit log):
>
> java.lang.IllegalArgumentException: Status code may not be negative.
> at
> org.apache.http.message.BasicStatusLine.<init>(BasicStatusLine.java:74)
> at
> org.apache.http.message.BasicLineParser.createStatusLine(BasicLineParser.java:453)
> at
> org.apache.http.message.BasicLineParser.parseStatusLine(BasicLineParser.java:431)
> at
> org.apache.http.impl.nio.codecs.HttpResponseParser.createMessage(HttpResponseParser.java:75)
> at
> org.apache.http.impl.nio.codecs.AbstractMessageParser.parseHeadLine(AbstractMessageParser.java:147)
> at
> org.apache.http.impl.nio.codecs.AbstractMessageParser.parse(AbstractMessageParser.java:196)
> at
> org.apache.http.impl.nio.DefaultNHttpClientConnection.consumeInput(DefaultNHttpClientConnection.java:160)
> at
> org.apache.http.impl.nio.DefaultClientIOEventDispatch.inputReady(DefaultClientIOEventDispatch.java:146)
> at
> org.apache.http.impl.nio.reactor.BaseIOReactor.readable(BaseIOReactor.java:153)
> at
> org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvent(AbstractIOReactor.java:314)
> at
> org.apache.http.impl.nio.reactor.AbstractIOReactor.processEvents(AbstractIOReactor.java:294)
> at
> org.apache.http.impl.nio.reactor.AbstractIOReactor.execute(AbstractIOReactor.java:256)
> at
> org.apache.http.impl.nio.reactor.BaseIOReactor.execute(BaseIOReactor.java:96)
> at
> org.apache.http.impl.nio.reactor.AbstractMultiworkerIOReactor$Worker.run(AbstractMultiworkerIOReactor.java:556)
> at java.lang.Thread.run(Thread.java:619)
>
>
> I used the setExceptionHandler() method to override the default exception
> handler for my ConnectingIOReactor object, here's my implementation:
>
> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> public class MyIOReactorExceptionHandler implements
> IOReactorExceptionHandler
> {
>
> public boolean handle(IOException arg0)
> {
> System.err.println("MyIOReactorExceptionHandler encountered
> IOException: " + arg0);
> return true;
> }
>
> public boolean handle(RuntimeException arg0)
> {
> System.err.println("MyIOReactorExceptionHandler encountered
> RuntimeException: " + arg0);
>
> //Ignore this one
> if (arg0 instanceof IllegalArgumentException &&
> arg0.getMessage().contains("Status code may not be negative."))
> {
> System.err.println("...ignoring recoverable error: " +
> arg0.getMessage());
> return false;
> }
>
> System.err.println("Signaling unrecoverable error...");
>
> return true;
> }
>
> }
>

Chas,

It is the other way around. The handler should return true if it is safe
to ignore the exception and continue execution of the I/O reactor and if
the I/O reactor must re-throw RuntimeException and terminate.

> ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Looking my program logs, it seems like the handle(RuntimeException) method
> is called, and "ignoring recoverable error: ..." is printed, but the
> IOReactor still shuts down.
>
> What am I missing here? Is there a better way to recover from this error
> without shutting down the IOReactor?
>

A better solution to this problem would be a custom message parser.

Hope this helps

Oleg

> Thanks,
>
> Chas
>

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