Chas Williams wrote:
Well, that's embarrassing ;). Thanks Oleg.
It is equally embarrassing to be responsible for having designed a
non-intuitive API ;) Boolean return values are evil. I never get them right.
I made some changes to the SVN trunk to improve handling of negative
HTTP status codes. As of 4.1-BETA1 HttpCore will throw a checked
ProtocolException instead of IllegalArgumentExcpetion in such a case.
Cheers
Oleg
On Tue, Jun 30, 2009 at 3:22 PM, Oleg Kalnichevski <[email protected]> wrote:
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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