Allocation and locks in Synthesiser::findVoiceToSteal

General JUCE discussion
1 
    // this is a list of voices we can steal, sorted by how long they've been running
    Array<SynthesiserVoice*> usableVoices;
    usableVoices.ensureStorageAllocated (voices.size());

and

    /** Increases the array's internal storage to hold a minimum number of elements.

        Calling this before adding a large known number of elements means that
        the array won't have to keep dynamically resizing itself as the elements
        are added, and it'll therefore be more efficient.
    */
    void ensureStorageAllocated (int minNumElements)
    {
        const ScopedLockType lock (getLock());
        values.ensureAllocatedSize (minNumElements);
    }

This both locks and allocates.
This is called from processBlock too.
I’m not sure what other options are usable here, since voices.size() is not known at compile time…

2

Iterrate through the voices and determine which one you want to instantly stop, then return it. Alternatively you can just use it as a method to stop a voice and then return a spare one, allocated as a set of voices to use only when youve ran out. But you should also stop it so you dont run out or return nullptr etc.

3

juce::Array takes a CriticalSection type as a template parameter; its default is a DummyCriticalSection which does nothing when locked.

Personally I would keep track of active voices with an std::atomic.

4

The worst lock is actually in Synthesiser::processNextBlock.
(And similar in MPESynthesiser).

Ideally, that would have been a SpinLock or something that doesn’t involve a system call. Or even better - no lock at all. :slight_smile:

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