Update statistics for org.jboss.netty.channel.FileRegion writes

[whiter4bbit]

Handle FileRegion writes in ChannelStatsHandler

Problem

Currently, when writing instance of FileRegion (in custom Codec for example), handler logs many annoying messages:

WAR [20141220-05:51:59.151] channel: ChannelStatsHandler received non-channelbuffer write

And sent bytes count from FileRegion not included in sent_bytes counter.

Solution

Check if message is instance of FileRegion and increment stats counters by FileRegion.getCount value

Result

Sent bytes from FileRegion are included in sent_bytes and connection_sent_bytes counters

[mosesn]

Very cool! Have you been doing any zero-copy stuff with finagle? I'd be very curious if you're able to share. Could you also update the "messageReceived" method to support FileRegion?

[whiter4bbit]

yes, I think, I can share example bit later, regarding messageReceived - this method invoked during upstream handling (for incoming message) and can never be FileRegion, sinceFileRegion can just transfer data to WritableByteChannel, but not read from 'readable' one.

[mosesn]

@trustin could you weigh in? I don't think I understand netty well enough to review this.

@whiter4bbit I thought part of the idea was that if you received a request, you could zero-copy that request elsewhere. It sounds like there's something I'm missing, is there some documentation or code I should read? I tried googling for information about netty + FileRegion, but didn't come up with anything that could help me understand it.

[trustin]

This pull request itself looks good to me.

However, I think it's not a good idea to increase the counters at writeRequested(), because it only tells us when a write operation has been requested, not when the write operation has been actually fulfilled.

I would recommend overriding SimpleChannelUpstreamHandler.writeComplete() and get the number of written bytes via WriteCompletionEvent.getWrittenAmount().

[mosesn]

@whiter4bbit I just wanted to make sure this PR didn't get lost between the cracks.

[whiter4bbit]

was out of time, I will try to 're-implement things in way that @trustin proposed

[mosesn]

Thanks!

[whiter4bbit]

Created new PR: #355