Re: [Discuss-gnuradio] Shared resource for source and sink blocks

[N. Benes]

N. Benes:
> what is the accepted best practice to have a source and a sink block
> share a common resource?
> In my case, the shared resource is a thread that does I/O and both
> source/sink use it to interface to GNU Radio.

[snip]

> Is there a commonly accepted pattern to apply in this situation?

I had a look at the UHD/USRP source:

https://github.com/EttusResearch/uhd/tree/master/host/lib/

The usrp_block_impl in GNU Radio creates a new instance of
::uhd::usrp::multi_usrp which internally retrieves a device from a
static map, either creating a new device or re-using an already existing
one:

https://github.com/EttusResearch/uhd/blob/master/host/lib/device.cpp#L175

> device::sptr device::make(const device_addr_t &hint, device_filter_t filter, 
> size_t which){
...
>     //map device address hash to created devices
>     static uhd::dict<size_t, boost::weak_ptr<device> > hash_to_device;
> 
>     //try to find an existing device
>     if (hash_to_device.has_key(dev_hash) and not 
> hash_to_device[dev_hash].expired()){
>         return hash_to_device[dev_hash].lock();
>     }
>     else {
>         // Add keys from the config files (note: the user-defined keys will
>         // always be applied, see also get_usrp_args()
>         // Then, create and register a new device.
>         device::sptr dev = maker(prefs::get_usrp_args(dev_addr));
>         hash_to_device[dev_hash] = dev;
>         return dev;
>     }
> }

So this seems to be a suitable pattern for my case.

Cheers,
nicolas