vboMemoryManager.h

//
// Copyright 2016 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
//    names, trademarks, service marks, or product names of the Licensor
//    and its affiliates, except as required to comply with Section 4(c) of
//    the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
#ifndef PXR_IMAGING_HD_ST_VBO_MEMORY_MANAGER_H
#define PXR_IMAGING_HD_ST_VBO_MEMORY_MANAGER_H

#include "pxr/pxr.h"
#include "pxr/imaging/hdSt/api.h"
#include "pxr/imaging/hd/version.h"
#include "pxr/imaging/hd/bufferArray.h"
#include "pxr/imaging/hdSt/bufferArrayRange.h"
#include "pxr/imaging/hd/bufferSpec.h"
#include "pxr/imaging/hd/bufferSource.h"
#include "pxr/imaging/hd/strategyBase.h"

#include "pxr/base/tf/mallocTag.h"
#include "pxr/base/tf/token.h"

#include <list>
#include <memory>

PXR_NAMESPACE_OPEN_SCOPE

class HdStResourceRegistry;

class HdStVBOMemoryManager : public HdAggregationStrategy
{
public:
    HdStVBOMemoryManager(HdStResourceRegistry *resourceRegistry)
    : HdAggregationStrategy()
    , _resourceRegistry(resourceRegistry) {}

    HDST_API
    virtual HdBufferArraySharedPtr CreateBufferArray(
        TfToken const &role,
        HdBufferSpecVector const &bufferSpecs,
        HdBufferArrayUsageHint usageHint);

    HDST_API
    virtual HdBufferArrayRangeSharedPtr CreateBufferArrayRange();

    HDST_API
    virtual AggregationId ComputeAggregationId(
        HdBufferSpecVector const &bufferSpecs,
        HdBufferArrayUsageHint usageHint) const;

    virtual HdBufferSpecVector GetBufferSpecs(
        HdBufferArraySharedPtr const &bufferArray) const;

    virtual size_t GetResourceAllocation(
        HdBufferArraySharedPtr const &bufferArray, 
        VtDictionary &result) const;

protected:
    class _StripedBufferArray;

    class _StripedBufferArrayRange : public HdStBufferArrayRange
    {
    public:
        _StripedBufferArrayRange(HdStResourceRegistry* resourceRegistry)
         : HdStBufferArrayRange(resourceRegistry),
           _stripedBufferArray(nullptr),
           _elementOffset(0),
           _numElements(0),
           _capacity(0)
        {
        }

        HDST_API
        ~_StripedBufferArrayRange() override;

        bool IsValid() const override {
            return (bool)_stripedBufferArray;
        }

        HDST_API
        bool IsAssigned() const override;

        bool IsImmutable() const override;

        HDST_API
        bool Resize(int numElements) override;

        HDST_API
        void CopyData(HdBufferSourceSharedPtr const &bufferSource) override;

        HDST_API
        VtValue ReadData(TfToken const &name) const override;

        int GetElementOffset() const override {
            return _elementOffset;
        }

        int GetByteOffset(TfToken const& resourceName) const override;

        size_t GetNumElements() const override {
            return _numElements;
        }

        size_t GetVersion() const override {
            return _stripedBufferArray->GetVersion();
        }

        void IncrementVersion() override {
            _stripedBufferArray->IncrementVersion();
        }

        HDST_API
        size_t GetMaxNumElements() const override;

        HDST_API
        HdBufferArrayUsageHint GetUsageHint() const override;

        HDST_API
        HdStBufferResourceSharedPtr GetResource() const override;

        HDST_API
        HdStBufferResourceSharedPtr GetResource(TfToken const& name) override;

        HDST_API
        HdStBufferResourceNamedList const& GetResources() const override;

        HDST_API
        void SetBufferArray(HdBufferArray *bufferArray) override;

        HDST_API
        void DebugDump(std::ostream &out) const override;

        void SetElementOffset(int offset) {
            _elementOffset = offset;
        }

        void SetNumElements(int numElements) {
            _numElements = numElements;
        }

        int GetCapacity() const {
            return _capacity;
        }

        void SetCapacity(int capacity) {
            _capacity = capacity;
        }

        void Invalidate() {
            _stripedBufferArray = NULL;
        }

    protected:
        HDST_API
        const void *_GetAggregation() const override;

    private:
        // Returns the byte offset at which the BAR begins for the resource.
        size_t _GetByteOffset(HdStBufferResourceSharedPtr const& resource)
            const;

        // holding a weak reference to container.
        // this pointer becomes null when the StripedBufferArray gets destructed,
        // in case if any drawItem still holds this bufferRange.
        _StripedBufferArray *_stripedBufferArray;
        int _elementOffset;
        size_t _numElements;
        int _capacity;
    };

    using _StripedBufferArraySharedPtr =
        std::shared_ptr<_StripedBufferArray>;
    using _StripedBufferArrayRangeSharedPtr =
        std::shared_ptr<_StripedBufferArrayRange>;
    using _StripedBufferArrayRangePtr = 
        std::weak_ptr<_StripedBufferArrayRange>;

    class _StripedBufferArray : public HdBufferArray
    {
    public:
        HDST_API
        _StripedBufferArray(HdStResourceRegistry* resourceRegistry,
                            TfToken const &role,
                            HdBufferSpecVector const &bufferSpecs,
                            HdBufferArrayUsageHint usageHint);

        HDST_API
        ~_StripedBufferArray() override;

        HDST_API
        bool GarbageCollect() override;

        HDST_API
        void DebugDump(std::ostream &out) const override;

        HDST_API
        void Reallocate(
            std::vector<HdBufferArrayRangeSharedPtr> const &ranges,
            HdBufferArraySharedPtr const &curRangeOwner) override;

        HDST_API
        size_t GetMaxNumElements() const override;

        void SetNeedsReallocation() {
            _needsReallocation = true;
        }

        void SetNeedsCompaction() {
            _needsCompaction = true;
        }


        HDST_API
        HdStBufferResourceSharedPtr GetResource() const;

        HDST_API
        HdStBufferResourceSharedPtr GetResource(TfToken const& name);

        HdStBufferResourceNamedList const& GetResources() const 
            {return _resourceList;}

        HDST_API
        HdBufferSpecVector GetBufferSpecs() const;

    protected:
        HDST_API
        void _DeallocateResources();

        HDST_API
        HdStBufferResourceSharedPtr _AddResource(TfToken const& name,
                                                   HdTupleType tupleType,
                                                   int offset,
                                                   int stride);

    private:

        HdStResourceRegistry* _resourceRegistry;
        bool _needsCompaction;
        int _totalCapacity;
        size_t _maxBytesPerElement;

        HdStBufferResourceNamedList _resourceList;

        // Helper routine to cast the range shared pointer.
        _StripedBufferArrayRangeSharedPtr _GetRangeSharedPtr(size_t idx) const {
            return std::static_pointer_cast<_StripedBufferArrayRange>(GetRange(idx).lock());
        }
    };
    
    HdStResourceRegistry* _resourceRegistry;
};

PXR_NAMESPACE_CLOSE_SCOPE

#endif  // PXR_IMAGING_HD_ST_VBO_MEMORY_MANAGER_H