# Put a block to sleep **URL:** \ **Category:** GNU Radio\ **Created:** [May 21, 2014, 11:54am UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268 "2014-05-21T11:54:46Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [May 21, 2014, 11:54am UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268/1 "2014-05-21T11:54:46Z")
Hello everybody, I want to connect a source to a sink block but there must be a sort of synchronization between them. The sink block should ask the source to generate data stream on some specific instances. Between these instances, the source block must put to the sleep or be disabled. How could I do this? I thought it was possible with exchanging messages between these two blocks by which the sink block send a message to the source to disable or enable it. But this doesn’t work because the scheduler will remain on the source after generating only one block of data (I need to generate just one block) at the start up of the flowgraph! best, Mostafa ---
**Author:** ![mostafa\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5e9695/32.png) [@mostafa\_a](https://www.ruby-forum.com/u/mostafa_a)\ **Post date:** [May 21, 2014, 12:50pm UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268/2 "2014-05-21T12:50:47Z")
On Wed, May 21, 2014 at 5:53 PM, Mostafa A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)wrote: > Hello everybody, > > I want to connect a source to a sink block but there must be a sort of > synchronization between them. The sink block should ask the source to > generate data stream on some specific instances. Between these instances, > the source block must put to the sleep or be disabled. How could I do this? The scheduler takes care of this. You don’t need to worry this. I thought it was possible with exchanging messages between these two > blocks by which the sink block send a message to the source to disable or > enable it. But this doesn’t work because the scheduler will remain on the > source after generating only one block of data (I need to generate just one > block) at the start up of the flowgraph! If you just need to generate only one block of data (one element), then you may not need gnuradio. ---
**Author:** ![mostafa\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5e9695/32.png) [@mostafa\_a](https://www.ruby-forum.com/u/mostafa_a)\ **Post date:** [May 21, 2014, 2:54pm UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268/3 "2014-05-21T14:54:36Z")
On 21.05.2014 11:53, Mostafa A. wrote: > or enable it. But this doesn’t work because the scheduler will remain on > the source after generating only one block of data (I need to generate > just one block) at the start up of the flowgraph! If you just need one block, you can use blocks.head. To “keep your block alive”, you can use a heartbeat message: Give your block another message port, and use the message strobe to send it messages every N ms. Once it’s alive, you can figure out if you need your source to send more data. M ---
**Author:** ![mostafa\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5e9695/32.png) [@mostafa\_a](https://www.ruby-forum.com/u/mostafa_a)\ **Post date:** [May 22, 2014, 1:23pm UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268/4 "2014-05-22T13:23:41Z")
It doesn’t work for me! ---
**Author:** ![mostafa\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/5e9695/32.png) [@mostafa\_a](https://www.ruby-forum.com/u/mostafa_a)\ **Post date:** [May 21, 2014, 3:49pm UTC](https://www.ruby-forum.com/t/put-a-block-to-sleep/241268/5 "2014-05-21T15:49:58Z")
Hi Martin, _blocks.head_ isn’t appropriate for my case because this is not a test! I searched for managing a thread, I found this : [http://www.boost.org/doc/libs/1\_48\_0/doc/html/thread/synchronization.html#thread.synchronization.condvar\_ref](http://www.boost.org/doc/libs/1_48_0/doc/html/thread/synchronization.html#thread.synchronization.condvar_ref) which is a part of boost library. This is exactly what I want, but I don’t know how I could use these classes in GNURadio!? The message passing mechanisms in GNURadio needs a block to be alive(as far as I know), but here I think I should put the block ( or the thread) to sleep and wake it up by a signal.