HttpAsyncContentProducer & IOControl

[Bill Speirs <bi...@gmail.com>]

I'm working on implementing an HttpAsyncContentProducer. The content
requires some blocking to produce, so instead of tying up the IO thread, I
*believe* I need to use the IOControl method suspendOutput() to prevent
future calls to produceContent(). However this opens up the question, how
do I inform the IO thread to start calling produceContent() again? Do I
need to save a reference to the IOControl object in the thread producing
the content, and then have that thread call requestOutput()?

Essentially, what would the pseudocode look like for
an HttpAsyncContentProducer that must block to product it's content?

Thanks!

Bill-

Re: HttpAsyncContentProducer & IOControl

[Oleg Kalnichevski <ol...@apache.org>]

On Wed, 2012-10-03 at 12:59 -0400, Bill Speirs wrote:
> I'm working on implementing an HttpAsyncContentProducer. The content
> requires some blocking to produce, so instead of tying up the IO thread, I
> *believe* I need to use the IOControl method suspendOutput() to prevent
> future calls to produceContent(). However this opens up the question, how
> do I inform the IO thread to start calling produceContent() again? Do I
> need to save a reference to the IOControl object in the thread producing
> the content, and then have that thread call requestOutput()?
> 

Yes, that is what you should be doing. Essentially, what you need a
shared buffer protected by a mutex used by the I/O reactor to read data
from or write data to the underlying connection and by a worker thread
to produce data to or consume data from the buffer.

http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/httpcore-nio/src/main/java/org/apache/http/nio/util/SharedInputBuffer.java
http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/httpcore-nio/src/main/java/org/apache/http/nio/util/SharedOutputBuffer.java 

> Essentially, what would the pseudocode look like for
> an HttpAsyncContentProducer that must block to product it's content?
> 
> Thanks!
> 
> Bill-

There are currently no good examples in HC, unfortunately. A good
reference implementation can be the async HTTP client conduit in Apache
CXF:

http://svn.apache.org/repos/asf/cxf/trunk/rt/transports/http-hc/src/main/java/org/apache/cxf/transport/http/asyncclient/

Hope this helps

Oleg 


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