[Discuss-gnuradio] Dropping RX buffer or Stopping usrp Sampling from cpp block

[e . jahandar]

Hi All, i have problem with USRP2 & Gnuradio.

i'm creating a adaptive filtering gnu radio block which receives a number of samples ( 2channel , usally 400,000 ) and process them in order to removing static clutters from the sampled signals.

the problem is here, the block is very slow, it takes 4sec to compute and produce results. so I'm finding a way to drop the unprocessed samples while running adaptive filter. usally gnu radio will buffer the samples and passing them by work function.

my problem is when when i received 400k samples and they are under adaptive filter processing, gnu radio buffers the rest of them and when the af processing ends up, gnu radio passes the next 400k samples which is old as 6sec.

so i am finding a way to drop the samples which i doesn't need them. first i write a program to measure processing time and multiplying it by sample rate and put it in global variable and drop the samples in next run of work function, by this program i receive newest samples always but the problem is manually dropping samples are time consuming. is there any way to gnu radio do it for me ? i also used stop function for usrp but it causes to crash my application. 
I developed the app using gnu radio block howto and passing the usrp object directly from python to my cpp block.

any idea?