Support for asynchronous calls

[SanderMertens]

Since function calls in Corto can be executed on a remote node, having to do a blocking wait for a response (in order to mimic 'traditional' function behavior) could hurt application performance. To address this, Corto should support calling functions asynchronously.

It would be nice if the user could decide whether to call a certain function asynchronously or not. Therefore, the language binding should allow for an extra way to call a method asynchronously. For example, the following corto definition:

int32 add(int32 a, int32 b)

could result in the following generated code (simplified- not showing casting macro's):

void add_async(corto_int32 a, corto_int32 b, corto_int32Callback callback);

Another option could be to allow for the function result to be posted to a dispatcher:

void add_dispatch(corto_int32 a, corto_int32 b, corto_int32Callback callback, corto_dispatcher dispatcher);

The latter would be more flexible, since it would allow the result of the function to be dispatched to a specific thread.