Carla/source/backend/CarlaPlugin.hpp

/*
 * Carla Plugin Host
 * Copyright (C) 2011-2014 Filipe Coelho <falktx@falktx.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * For a full copy of the GNU General Public License see the doc/GPL.txt file.
 */

#ifndef CARLA_PLUGIN_HPP_INCLUDED
#define CARLA_PLUGIN_HPP_INCLUDED

#include "CarlaBackend.h"

// -----------------------------------------------------------------------
// Avoid including extra libs here

typedef void* lo_address;
typedef struct _NativePluginDescriptor NativePluginDescriptor;
struct LADSPA_RDF_Descriptor;

// -----------------------------------------------------------------------

CARLA_BACKEND_START_NAMESPACE

#if 0
} /* Fix editor indentation */
#endif

// -----------------------------------------------------------------------

/*!
 * @defgroup CarlaPluginAPI Carla Plugin API
 *
 * The Carla Plugin API.
 * @{
 */

class CarlaEngineAudioPort;

/*!
 * Save state data.
 */
struct SaveState;

/*!
 * Protected data used in CarlaPlugin and subclasses.\n
 * Non-plugin code MUST NEVER have direct access to this.
 */
struct CarlaPluginProtectedData;

// -----------------------------------------------------------------------

/*!
 * Carla Backend base plugin class
 *
 * This is the base class for all available plugin types available in Carla Backend.\n
 * All virtual calls are implemented in this class as fallback (except reload and process),\n
 * so it's safe to only override needed calls.
 *
 * \see PluginType
 */
class CarlaPlugin
{
protected:
    /*!
     * This is the constructor of the base plugin class.
     *
     * \param engine The engine which this plugin belongs to, must not be null
     * \param id     The 'id' of this plugin, must be between 0 and CarlaEngine::maxPluginNumber()
     */
    CarlaPlugin(CarlaEngine* const engine, const unsigned int id);

public:
    /*!
     * This is the destructor of the base plugin class.
     */
    virtual ~CarlaPlugin();

    // -------------------------------------------------------------------
    // Information (base)

    /*!
     * Get the plugin's type (a subclass of CarlaPlugin).
     *
     * \note Plugin bridges will return their respective plugin type, there is no plugin type such as "bridge".\n
     *       To check if a plugin is a bridge use:
     * \code
     * if (getHints() & PLUGIN_IS_BRIDGE)
     *     ...
     * \endcode
     */
    virtual PluginType getType() const noexcept = 0;

    /*!
     * Get the plugin's id (as passed in the constructor).
     *
     * \see setId()
     */
    unsigned int getId() const noexcept;

    /*!
     * Get the plugin's hints.
     *
     * \see PluginHints
     */
    unsigned int getHints() const noexcept;

    /*!
     * Get the plugin's options (currently in use).
     *
     * \see PluginOptions, getAvailableOptions() and setOption()
     */
    unsigned int getOptionsEnabled() const noexcept;

    /*!
     * Check if the plugin is enabled.\n
     * When a plugin is disabled, it will never be processed or managed in any way.
     *
     * \see setEnabled()
     */
    bool isEnabled() const noexcept;

    /*!
     * Get the plugin's internal name.\n
     * This name is unique within all plugins in an engine.
     *
     * \see getRealName() and setName()
     */
    const char* getName() const noexcept;

    /*!
     * Get the currently loaded DLL filename for this plugin.\n
     * (Sound kits return their exact filename).
     */
    const char* getFilename() const noexcept;

    /*!
     * Get the plugins's icon name.
     */
    const char* getIconName() const noexcept;

    /*!
     * Get the plugin's category (delay, filter, synth, etc).
     */
    virtual PluginCategory getCategory() const noexcept;

    /*!
     * Get the plugin's native unique Id.\n
     * May return 0 on plugin types that don't support Ids.
     */
    virtual int64_t getUniqueId() const noexcept;

    /*!
     * Get the plugin's latency, in sample frames.
     */
    uint32_t getLatencyInFrames() const noexcept;

    // -------------------------------------------------------------------
    // Information (count)

    /*!
     * Get the number of audio inputs.
     */
    uint32_t getAudioInCount() const noexcept;

    /*!
     * Get the number of audio outputs.
     */
    uint32_t getAudioOutCount() const noexcept;

    /*!
     * Get the number of MIDI inputs.
     */
    virtual uint32_t getMidiInCount() const noexcept;

    /*!
     * Get the number of MIDI outputs.
     */
    virtual uint32_t getMidiOutCount() const noexcept;

    /*!
     * Get the number of parameters.\n
     * To know the number of parameter inputs and outputs separately use getParameterCountInfo() instead.
     */
    uint32_t getParameterCount() const noexcept;

    /*!
     * Get the number of scalepoints for parameter \a parameterId.
     */
    virtual uint32_t getParameterScalePointCount(const uint32_t parameterId) const noexcept;

    /*!
     * Get the number of programs.
     */
    uint32_t getProgramCount() const noexcept;

    /*!
     * Get the number of MIDI programs.
     */
    uint32_t getMidiProgramCount() const noexcept;

    /*!
     * Get the number of custom data sets.
     */
    uint32_t getCustomDataCount() const noexcept;

    // -------------------------------------------------------------------
    // Information (current data)

    /*!
     * Get the current program number (-1 if unset).
     *
     * \see setProgram()
     */
    int32_t getCurrentProgram() const noexcept;

    /*!
     * Get the current MIDI program number (-1 if unset).
     *
     * \see setMidiProgram()
     * \see setMidiProgramById()
     */
    int32_t getCurrentMidiProgram() const noexcept;

    /*!
     * Get the parameter data of \a parameterId.
     */
    const ParameterData& getParameterData(const uint32_t parameterId) const noexcept;

    /*!
     * Get the parameter ranges of \a parameterId.
     */
    const ParameterRanges& getParameterRanges(const uint32_t parameterId) const noexcept;

    /*!
     * Check if parameter \a parameterId is of output type.
     */
    bool isParameterOutput(const uint32_t parameterId) const noexcept;

    /*!
     * Get the MIDI program at \a index.
     *
     * \see getMidiProgramName()
     */
    const MidiProgramData& getMidiProgramData(const uint32_t index) const noexcept;

    /*!
     * Get the custom data set at \a index.
     *
     * \see getCustomDataCount() and setCustomData()
     */
    const CustomData& getCustomData(const uint32_t index) const noexcept;

    /*!
     * Get the complete plugin chunk data into \a dataPtr.
     *
     * \note Make sure to verify the plugin supports chunks before calling this function!
     * \return The size of the chunk or 0 if invalid.
     *
     * \see setChunkData()
     */
    virtual int32_t getChunkData(void** const dataPtr) const noexcept;

    // -------------------------------------------------------------------
    // Information (per-plugin data)

    /*!
     * Get the plugin available options.
     *
     * \see PluginOptions, getOptions() and setOption()
     */
    virtual unsigned int getOptionsAvailable() const noexcept;

    /*!
     * Get the current parameter value of \a parameterId.
     */
    virtual float getParameterValue(const uint32_t parameterId) const noexcept;

    /*!
     * Get the scalepoint \a scalePointId value of the parameter \a parameterId.
     */
    virtual float getParameterScalePointValue(const uint32_t parameterId, const uint32_t scalePointId) const noexcept;

    /*!
     * Get the plugin's label (URI for LV2 plugins).
     */
    virtual void getLabel(char* const strBuf) const noexcept;

    /*!
     * Get the plugin's maker.
     */
    virtual void getMaker(char* const strBuf) const noexcept;

    /*!
     * Get the plugin's copyright/license.
     */
    virtual void getCopyright(char* const strBuf) const noexcept;

    /*!
     * Get the plugin's (real) name.
     *
     * \see getName() and setName()
     */
    virtual void getRealName(char* const strBuf) const noexcept;

    /*!
     * Get the name of the parameter \a parameterId.
     */
    virtual void getParameterName(const uint32_t parameterId, char* const strBuf) const noexcept;

    /*!
     * Get the symbol of the parameter \a parameterId.
     */
    virtual void getParameterSymbol(const uint32_t parameterId, char* const strBuf) const noexcept;

    /*!
     * Get the custom text of the parameter \a parameterId.
     */
    virtual void getParameterText(const uint32_t parameterId, char* const strBuf) const noexcept;

    /*!
     * Get the unit of the parameter \a parameterId.
     */
    virtual void getParameterUnit(const uint32_t parameterId, char* const strBuf) const noexcept;

    /*!
     * Get the scalepoint \a scalePointId label of the parameter \a parameterId.
     */
    virtual void getParameterScalePointLabel(const uint32_t parameterId, const uint32_t scalePointId, char* const strBuf) const noexcept;

    /*!
     * Get the current parameter value of \a parameterId.
     * \a parameterId can be negative to allow internal parameters.
     * \see InternalParametersIndex
     */
    float getInternalParameterValue(const int32_t parameterId) const noexcept;

    /*!
     * Get the name of the program at \a index.
     */
    void getProgramName(const uint32_t index, char* const strBuf) const noexcept;

    /*!
     * Get the name of the MIDI program at \a index.
     *
     * \see getMidiProgramInfo()
     */
    void getMidiProgramName(const uint32_t index, char* const strBuf) const noexcept;

    /*!
     * Get information about the plugin's parameter count.\n
     * This is used to check how many input, output and total parameters are available.\n
     *
     * \note Some parameters might not be input or output (ie, invalid).
     *
     * \see getParameterCount()
     */
    void getParameterCountInfo(uint32_t& ins, uint32_t& outs) const noexcept;

    // -------------------------------------------------------------------
    // Set data (state)

    /*!
     * Tell the plugin to prepare for save.
     */
    virtual void prepareForSave();

    /*!
     * Get the plugin's save state.\n
     * The plugin will automatically call prepareForSave() as needed.
     *
     * \see loadSaveState()
     */
    const SaveState& getSaveState();

    /*!
     * Get the plugin's save state.
     *
     * \see getSaveState()
     */
    void loadSaveState(const SaveState& saveState);

    /*!
     * Save the current plugin state to \a filename.
     *
     * \see loadStateFromFile()
     */
    bool saveStateToFile(const char* const filename);

    /*!
     * Save the plugin state from \a filename.
     *
     * \see saveStateToFile()
     */
    bool loadStateFromFile(const char* const filename);

    // -------------------------------------------------------------------
    // Set data (internal stuff)

    /*!
     * Set the plugin's id to \a newId.
     *
     * \see getId()
     */
    void setId(const unsigned int newId) noexcept;

    /*!
     * Set the plugin's name to \a newName.
     *
     * \see getName() and getRealName()
     */
    virtual void setName(const char* const newName);

    /*!
     * Set a plugin's option.
     *
     * \see getOptions() and getAvailableOptions()
     */
    void setOption(const unsigned int option, const bool yesNo);

    /*!
     * Enable or disable the plugin according to \a yesNo. \n
     * When a plugin is disabled, it will never be processed or managed in any way.
     *
     * \see isEnabled()
     */
    void setEnabled(const bool yesNo) noexcept;

    /*!
     * Set plugin as active according to \a active.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     */
    void setActive(const bool active, const bool sendOsc, const bool sendCallback) noexcept;

#ifndef BUILD_BRIDGE
    /*!
     * Set the plugin's dry/wet signal value to \a value.\n
     * \a value must be between 0.0 and 1.0.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     */
    void setDryWet(const float value, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set the plugin's output volume to \a value.\n
     * \a value must be between 0.0 and 1.27.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     */
    void setVolume(const float value, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set the plugin's output left balance value to \a value.\n
     * \a value must be between -1.0 and 1.0.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     *
     * \note Pure-Stereo plugins only!
     */
    void setBalanceLeft(const float value, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set the plugin's output right balance value to \a value.\n
     * \a value must be between -1.0 and 1.0.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     *
     * \note Pure-Stereo plugins only!
     */
    void setBalanceRight(const float value, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set the plugin's output panning value to \a value.\n
     * \a value must be between -1.0 and 1.0.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     *
     * \note Force-Stereo plugins only!
     */
    void setPanning(const float value, const bool sendOsc, const bool sendCallback) noexcept;
#endif

    /*!
     * Set the plugin's midi control channel.
     *
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     */
    virtual void setCtrlChannel(const int8_t channel, const bool sendOsc, const bool sendCallback) noexcept;

    // -------------------------------------------------------------------
    // Set data (plugin-specific stuff)

    /*!
     * Set a plugin's parameter value.
     *
     * \param parameterId The parameter to change
     * \param value The new parameter value, must be within the parameter's range
     * \param sendGui Send message change to plugin's custom GUI, if any
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     *
     * \see getParameterValue()
     */
    virtual void setParameterValue(const uint32_t parameterId, const float value, const bool sendGui, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set a plugin's parameter value, including internal parameters.\n
     * \a rindex can be negative to allow internal parameters change (as defined in InternalParametersIndex).
     *
     * \see setParameterValue()
     * \see setActive()
     * \see setDryWet()
     * \see setVolume()
     * \see setBalanceLeft()
     * \see setBalanceRight()
     */
    void setParameterValueByRealIndex(const int32_t rindex, const float value, const bool sendGui, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set parameter's \a parameterId MIDI channel to \a channel.\n
     * \a channel must be between 0 and 15.
     */
    void setParameterMidiChannel(const uint32_t parameterId, uint8_t channel, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Set parameter's \a parameterId MIDI CC to \a cc.\n
     * \a cc must be between 0 and 95 (0x5F), or -1 for invalid.
     */
    void setParameterMidiCC(const uint32_t parameterId, int16_t cc, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Add a custom data set.\n
     * If \a key already exists, its current value will be swapped with \a value.
     *
     * \param type Type of data used in \a value.
     * \param key A key identifing this data set.
     * \param value The value of the data set, of type \a type.
     * \param sendGui Send message change to plugin's custom GUI, if any
     *
     * \see getCustomDataCount() and getCustomData()
     */
    virtual void setCustomData(const char* const type, const char* const key, const char* const value, const bool sendGui);

    /*!
     * Set the complete chunk data as \a stringData.\n
     * \a stringData must a base64 encoded string of binary data.
     *
     * \see getChunkData()
     *
     * \note Make sure to verify the plugin supports chunks before calling this function!
     */
    virtual void setChunkData(const char* const stringData);

    /*!
     * Change the current plugin program to \a index.
     *
     * If \a index is negative the plugin's program will be considered unset.\n
     * The plugin's default parameter values will be updated when this function is called.
     *
     * \param index New program index to use
     * \param sendGui Send message change to plugin's custom GUI, if any
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     * \param block Block the audio callback
     */
    virtual void setProgram(const int32_t index, const bool sendGui, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * Change the current MIDI plugin program to \a index.
     *
     * If \a index is negative the plugin's program will be considered unset.\n
     * The plugin's default parameter values will be updated when this function is called.
     *
     * \param index New program index to use
     * \param sendGui Send message change to plugin's custom GUI, if any
     * \param sendOsc Send message change over OSC
     * \param sendCallback Send message change to registered callback
     * \param block Block the audio callback
     */
    virtual void setMidiProgram(const int32_t index, const bool sendGui, const bool sendOsc, const bool sendCallback) noexcept;

    /*!
     * This is an overloaded call to setMidiProgram().\n
     * It changes the current MIDI program using \a bank and \a program values instead of index.
     */
    void setMidiProgramById(const uint32_t bank, const uint32_t program, const bool sendGui, const bool sendOsc, const bool sendCallback) noexcept;

    // -------------------------------------------------------------------
    // Set gui stuff

    /*!
     * Idle function.
     *
     * \note This function must be always called from the main thread.
     */
    virtual void idle();

    /*!
     * Show (or hide) the plugin's custom UI according to \a yesNo.
     *
     * \note This function must be always called from the main thread.
     */
    virtual void showCustomUI(const bool yesNo);

    // -------------------------------------------------------------------
    // Plugin state

    /*!
     * Reload the plugin's entire state (including programs).\n
     * The plugin will be disabled during this call.
     */
    virtual void reload() = 0;

    /*!
     * Reload the plugin's programs state.
     */
    virtual void reloadPrograms(const bool doInit);

    // -------------------------------------------------------------------
    // Plugin processing

    /*!
     * Plugin activate call.
     */
    virtual void activate() noexcept;

    /*!
     * Plugin activate call.
     */
    virtual void deactivate() noexcept;

    /*!
     * Plugin process call.
     */
    virtual void process(float** const inBuffer, float** const outBuffer, const uint32_t frames) = 0;

    /*!
     * Tell the plugin the current buffer size changed.
     */
    virtual void bufferSizeChanged(const uint32_t newBufferSize);

    /*!
     * Tell the plugin the current sample rate changed.
     */
    virtual void sampleRateChanged(const double newSampleRate);

    /*!
     * Tell the plugin the current offline mode changed.
     */
    virtual void offlineModeChanged(const bool isOffline);

#if 0
    /*!
     * Lock the plugin's master mutex.
     */
    void lock();
#endif

    /*!
     * Try to lock the plugin's master mutex.
     * @param forcedOffline When true, always locks and returns true
     */
    bool tryLock(const bool forcedOffline) noexcept;

    /*!
     * Unlock the plugin's master mutex.
     */
    void unlock() noexcept;

    // -------------------------------------------------------------------
    // Plugin buffers

    /*!
     * Initialize all RT buffers of the plugin.
     */
    virtual void initBuffers();

    /*!
     * Delete and clear all RT buffers.
     */
    virtual void clearBuffers();

    // -------------------------------------------------------------------
    // OSC stuff

    /*!
     * Register this plugin to the engine's OSC client (controller or bridge).
     */
    void registerToOscClient() noexcept;

    /*!
     * Update the plugin's internal OSC data according to \a source and \a url.\n
     * This is used for OSC-GUI bridges.
     */
    virtual void updateOscData(const lo_address& source, const char* const url);

    /*!
     * Free the plugin's internal OSC memory data.
     */
    //void freeOscData();

    /*!
     * Show the plugin's OSC based GUI.\n
     * This is a handy function that waits for the GUI to respond and automatically asks it to show itself.
     */
    bool waitForOscGuiShow();

    // -------------------------------------------------------------------
    // MIDI events

#ifndef BUILD_BRIDGE
    /*!
     * Send a single midi note to be processed in the next audio callback.\n
     * A note with 0 velocity means note-off.
     * \note Non-RT call
     */
    void sendMidiSingleNote(const uint8_t channel, const uint8_t note, const uint8_t velo, const bool sendGui, const bool sendOsc, const bool sendCallback);
#endif

    /*!
     * Send all midi notes off to the host callback.\n
     * This doesn't send the actual MIDI All-Notes-Off event, but 128 note-offs instead (IFF ctrlChannel is valid).
     * \note RT call
     */
    void sendMidiAllNotesOffToCallback();

    // -------------------------------------------------------------------
    // Post-poned events

    /*!
     * Process all the post-poned events.
     * This function must be called from the main thread (ie, idle()) if PLUGIN_USES_SINGLE_THREAD is set.
     */
    void postRtEventsRun();

    // -------------------------------------------------------------------
    // Post-poned UI Stuff

    /*!
     * Tell the UI a parameter has changed.
     */
    virtual void uiParameterChange(const uint32_t index, const float value) noexcept;

    /*!
     * Tell the UI the current program has changed.
     */
    virtual void uiProgramChange(const uint32_t index) noexcept;

    /*!
     * Tell the UI the current midi program has changed.
     */
    virtual void uiMidiProgramChange(const uint32_t index) noexcept;

    /*!
     * Tell the UI a note has been pressed.
     */
    virtual void uiNoteOn(const uint8_t channel, const uint8_t note, const uint8_t velo) noexcept;

    /*!
     * Tell the UI a note has been released.
     */
    virtual void uiNoteOff(const uint8_t channel, const uint8_t note) noexcept;

    // -------------------------------------------------------------------
    // Helper functions

    /*!
     * Check if the plugin can run in rack mode.
     */
    bool canRunInRack() const noexcept;

    /*!
     * Get the plugin's engine, as passed in the constructor.
     */
    CarlaEngine* getEngine() const noexcept;

    /*!
     * Get the plugin's engine client.
     */
    CarlaEngineClient* getEngineClient() const noexcept;

    /*!
     * Get a plugin's audio input port.
     */
    CarlaEngineAudioPort* getAudioInPort(const uint32_t index) const noexcept;

    /*!
     * Get a plugin's audio output port.
     */
    CarlaEngineAudioPort* getAudioOutPort(const uint32_t index) const noexcept;

    // -------------------------------------------------------------------
    // Plugin initializers

    /*!
     * Get a plugin's binary type.\n
     * This is always BINARY_NATIVE unless the plugin is a bridge.
     */
    virtual BinaryType getBinaryType() const noexcept
    {
        return BINARY_NATIVE;
    }

    /*!
     * Handy function required by CarlaEngine::clonePlugin().
     */
    virtual const void* getExtraStuff() const noexcept
    {
        return nullptr;
    }

#ifndef DOXYGEN
    struct Initializer {
        CarlaEngine* const engine;
        const unsigned int id;
        const char* const filename;
        const char* const name;
        const char* const label;
        const int64_t uniqueId;
    };

    static size_t getNativePluginCount() noexcept;
    static const NativePluginDescriptor* getNativePluginDescriptor(const size_t index) noexcept;

    static CarlaPlugin* newNative(const Initializer& init);
    static CarlaPlugin* newBridge(const Initializer& init, const BinaryType btype, const PluginType ptype, const char* const bridgeBinary);

    static CarlaPlugin* newLADSPA(const Initializer& init, const LADSPA_RDF_Descriptor* const rdfDescriptor);
    static CarlaPlugin* newDSSI(const Initializer& init);
    static CarlaPlugin* newLV2(const Initializer& init);
    static CarlaPlugin* newVST(const Initializer& init);
    static CarlaPlugin* newVST3(const Initializer& init);
    static CarlaPlugin* newAU(const Initializer& init);
    static CarlaPlugin* newJACK(const Initializer& init);
    static CarlaPlugin* newReWire(const Initializer& init);

    static CarlaPlugin* newCsound(const Initializer& init);
    static CarlaPlugin* newJuce(const Initializer& init, const char* const format);
    static CarlaPlugin* newFluidSynth(const Initializer& init, const bool use16Outs);
    static CarlaPlugin* newLinuxSampler(const Initializer& init, const char* const format, const bool use16Outs);

    static CarlaPlugin* newFileCSD(const Initializer& init);
    static CarlaPlugin* newFileGIG(const Initializer& init, const bool use16Outs);
    static CarlaPlugin* newFileSF2(const Initializer& init, const bool use16Outs);
    static CarlaPlugin* newFileSFZ(const Initializer& init);
#endif

    // -------------------------------------------------------------------

protected:
    /*!
     * Internal data, for CarlaPlugin subclasses only.
     */
    CarlaPluginProtectedData* const pData;
    friend struct CarlaPluginProtectedData;

    // -------------------------------------------------------------------
    // Helper classes

    /*!
     * Fully disable plugin in scope and also its engine client.\n
     * May wait-block on constructor for plugin process to end.
     */
    class ScopedDisabler
    {
    public:
        ScopedDisabler(CarlaPlugin* const plugin) noexcept;
        ~ScopedDisabler() noexcept;

    private:
        CarlaPlugin* const fPlugin;

        CARLA_PREVENT_HEAP_ALLOCATION
        CARLA_DECLARE_NON_COPY_CLASS(ScopedDisabler)
    };

    /*!
     * Lock the plugin's own run/process call.\n
     * Plugin will still work as normal, but output only silence.\n
     * On destructor needsReset flag might be set if the plugin might have missed some events.
     */
    class ScopedSingleProcessLocker
    {
    public:
        ScopedSingleProcessLocker(CarlaPlugin* const plugin, const bool block) noexcept;
        ~ScopedSingleProcessLocker() noexcept;

    private:
        CarlaPlugin* const fPlugin;
        const bool fBlock;

        CARLA_PREVENT_HEAP_ALLOCATION
        CARLA_DECLARE_NON_COPY_CLASS(ScopedSingleProcessLocker)
    };

    CARLA_DECLARE_NON_COPY_CLASS(CarlaPlugin)
};

/**@}*/

// -----------------------------------------------------------------------

CARLA_BACKEND_END_NAMESPACE

#endif // CARLA_PLUGIN_HPP_INCLUDED