cello_sync.h

/*
    Copyright (c) 2023 Brett g Porter
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
    SOFTWARE.
*/
 
#pragma once
 
#include <deque>
#include <juce_core/juce_core.h>
#include <juce_data_structures/juce_data_structures.h>
 
namespace cello
{
 
class Object;
 
class UpdateQueue
{
public:
    UpdateQueue (Object& consumer, juce::Thread* thread);
    virtual ~UpdateQueue () {}
    UpdateQueue (const UpdateQueue&)            = delete;
    UpdateQueue& operator= (const UpdateQueue&) = delete;
    UpdateQueue (UpdateQueue&&)                 = delete;
    UpdateQueue& operator= (UpdateQueue&&)      = delete;

    int getPendingUpdateCount () const;

    void performAllUpdates ();

    void performNextUpdate ();

    bool isDestinationThread (juce::Thread* thread) const { return thread == destThread; }
 
protected:
    void pushUpdate (juce::MemoryBlock&& update);

    virtual void startUpdate (void* data, size_t size) = 0;
    virtual void endUpdate () = 0;
 
private:
    Object& dest;
    juce::Thread* destThread;
    juce::CriticalSection mutex;
    std::deque<juce::MemoryBlock> queue;
};
 
class SyncController;

struct SyncData
{
    const char* data { nullptr };
    size_t size { 0 };
 
    SyncData () = default;
    SyncData (const void* data_, size_t size_)
    : data (static_cast<const char*> (data_))
    , size (size_)
    {
    }
    bool operator== (const SyncData& other) const
    {
        if (size != other.size)
            return false;
        for (size_t i { 0 }; i < size; ++i)
            if (data[i] != other.data[i])
                return false;
        return true;
    }
    bool operator!= (const SyncData& other) const { return !(*this == other); }
};
 
class Sync : public UpdateQueue,
             public juce::ValueTreeSynchroniser
{
public:
    Sync (Object& producer, Object& consumer, juce::Thread* thread, SyncController* controller = nullptr);
 
    Sync (const Sync&)            = delete;
    Sync& operator= (const Sync&) = delete;
 
private:
    void stateChanged (const void* encodedChange, size_t encodedChangeSize) override;
 
    void startUpdate (void* data, size_t size) override;
    void endUpdate () override;
 
    SyncController* controller { nullptr };
};

class SyncController
{
public:
    SyncController (Object& obj1, juce::Thread* threadForObj1, Object& obj2, juce::Thread* threadForObj2);
    ~SyncController () = default;
 
    SyncController (const SyncController&)            = delete;
    SyncController& operator= (const SyncController&) = delete;
    SyncController (SyncController&&)                 = delete;
    SyncController& operator= (SyncController&&)      = delete;

    void performNextUpdate (juce::Thread* thread);

    void performAllUpdates (juce::Thread* thread);
 
private:
    Sync sync1to2;
    Sync sync2to1; 
 
    SyncData update1to2;
    SyncData update2to1;
 
    friend class Sync;
    void startUpdate (Sync* sync, void* data, size_t size);
    void endUpdate (Sync* sync);

    bool shouldHandleUpdate (Sync* sync, void* data, size_t size) const;
 
};
 
} // namespace cello