Enhancement Request - "monitor" a la Redis, potentially "monitor [grepStr]"

[GoogleCodeExporter]

What steps will reproduce the problem?
1. N/A - Enhancement request.

What is the expected output? What do you see instead?
N/A

What version of the product are you using? On what operating system?
N/A

Please provide any additional information below.
In Redis, I've fallen in love with the "monitor" command, which helps me debug 
even a simple interaction with the datastore.
http://redis.io/commands/monitor
Having something similar in memcached which would echo back command and keys 
(not bodies, probably) of real-life traffic would be super useful.
As an added bonus, it'd be great if we could limit the values that we are 
listening to by some string.

PS. Thanks for all you do!

Original issue reported on code.google.com by nelz9999@gmail.com on 17 Jul 2012 at 12:43

[GoogleCodeExporter]

I've wanted to do this for a long time. We have soemthing like that in 1.6's 
TAP, so we'll see if that comes along then.

It's difficult for us to do since we're multithreaded, so it has to do careful 
sampling tricks or whatnot to avoid having a significant impact. Or, simply 
only "monitor" the thread you're connected to. we'll see.

Original comment by dorma...@rydia.net on 24 Jul 2012 at 7:15