[fluid-dev] Re: FluidSynth event queue and thread safety changes

[josh]

I've been looking over the SoundFont and preset code in FluidSynth.   
Here is what I'm currently thinking of doing to resolve the threading  
issues:

- Add a hash table using the SoundFont ID as the key, which is  
protected by the Synth mutex.
- Create new structure which is used as values in the hash table,  
allows for additional fields to be applied to SoundFont instances and  
merge the SoundFont bank offset list functionality into it:

struct _fluid_sfont_priv_t
{
  int refcount;
  int bank_offset;
};

- When a Preset is created, a reference is added to its owning  
SoundFont and removed when the preset is destroyed

- Presets shouldn't be destroyed in synthesis thread, due to memory  
free(), so add another queue which goes in the other direction (synth  
thread to some main thread process), preset destroy events could then  
be sent.

Not quite as elegant as I'd like, but I can't think of a better way to  
do it properly and retain the current API.

I haven't yet thought through, how this "main" or other thread will  
actually go about processing the events sent from the synthesis thread.

Just wanted to run this by you, to see if you had any better ideas or  
see any problems with it.

Cheers!

Josh