<div dir="ltr">Comments below:<br><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Oct 22, 2013 at 7:46 AM, Steve Powell <span dir="ltr"><<a href="mailto:steve@rabbitmq.com" target="_blank">steve@rabbitmq.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div><div>On 22 Oct 2013, at 11:42, Steve Powell <<a href="mailto:steve@rabbitmq.com" target="_blank">steve@rabbitmq.com</a>> wrote:</div>
<br><blockquote type="cite">Issuing a 'real work' call after closing the channel, like <font face="American Typewriter">channel.basicConsume()</font>, throws an <font face="American Typewriter">AlreadyClosedException</font>, claiming that the connection is closed, but <font face="American Typewriter">conn.isOpen()</font> still returns true.</blockquote>
<div><br></div></div><div>Well, it appears that the <font face="American Typewriter">AlreadyClosedException</font> produces the "clean connection shutdown" string when it is a hard error (which is correct). It is called by the (internal) '<font face="American Typewriter">channel.ensureIsOpen()</font>' method (typically, if we are about to communicate across the channel). But the <font face="American Typewriter">reference</font> in the exception is then to a <font face="American Typewriter">Channel</font>, </div>
</div></blockquote><div><br></div><div>This is the workaround I've been using to determine if a Channel was closed versus a Connection - by looking at what type the reference is.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div style="word-wrap:break-word"><div>and although the exception implies that the connection has been closed, it hasn't. This appears to contradict the hard error flag: which is supposed to mean the <i>connection</i> is closed.</div>
<div><br></div><div>I guess this means that the bug is <i>the connection isn't closed by the application initiated call to a closed channel.</i> </div><div><br></div><div>You could argue this particular channel error doesn't violate the protocol, so there is no reason to suppose that the connection would (or should) be closed, so it shouldn't be a hard error. [The code comments imply that <font face="American Typewriter">hardError==true</font> implies that <font face="American Typewriter">getReference()</font> returns a <font face="American Typewriter">Connection</font> object, which is actually <i>not</i> true anyway.]</div>
<div><br></div><div>As this thread stated right at the beginning (see subject), there is no provision in the code for issuing an <font face="American Typewriter">AlreadyClosedException</font> without it being a hard error. If we could do this, the meaning of hardError would be preserved.</div>
<div><br></div><div>As in the case of referring to a consumer that the client has no record of, the client code can often determine if the channel is already closed, and <i>not</i> risk any protocol violations before throwing the exception. In these cases, it ought not to be a hard error: the connection can remain unaffected.</div>
</div></blockquote><div><br></div><div>That would be ideal, if an AlreadyClosedException due to an invocation against a closed Channel did not result in a Connection closure. The reason is (as we've been discussing in a separate thread: Channel.basicPublish to a non-existent exchange...) sometimes the client receives an AlreadyClosedException *before* they are ever notified that the Channel was closed. This happens if you're doing rapid basicPublish calls to a non-existent exchange. Eventually basicPublish fails with an AlreadyClosedException, but this often occurs before the Channel's ShutdownListener is called. So the client has no fair way of avoiding the AlreadyClosedException.</div>
<div><br></div><div>So from my perspective, there are a few things I'd prefer to see out of all this:</div><div><br></div><div>- That AlreadyClosedExceptions be allowed to represent channels that were already closed (as seems to be the case with the reference being set to a Channel).</div>
<div>- That an invocation against a Channel that has already been closed does not result in the Connection being closed (as seems to be the case).</div><div>- That AlreadyClosedExceptions include the Method that originally cased the closure as the shutdown reason (if any), such as 404. This would allow me to determine why a basicPublish fails.</div>
<div><br></div><div>Cheers,</div><div>Jonathan</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word"><div>
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