vtk-m2/vtkm/worklet/ScatterCounting.h
Kenneth Moreland d879188de0 Make DispatcherBase invoke using a TryExecute
Rather than force all dispatchers to be templated on a device adapter,
instead use a TryExecute internally within the invoke to select a device
adapter.

Because this removes the need to declare a device when invoking a
worklet, this commit also removes the need to declare a device in
several other areas of the code.
2018-08-29 19:18:54 -07:00

282 lines
10 KiB
C++

//=============================================================================
//
// Copyright (c) Kitware, Inc.
// All rights reserved.
// See LICENSE.txt for details.
//
// This software is distributed WITHOUT ANY WARRANTY; without even
// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
// PURPOSE. See the above copyright notice for more information.
//
// Copyright 2015 National Technology & Engineering Solutions of Sandia, LLC (NTESS).
// Copyright 2015 UT-Battelle, LLC.
// Copyright 2015 Los Alamos National Security.
//
// Under the terms of Contract DE-NA0003525 with NTESS,
// the U.S. Government retains certain rights in this software.
// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
// Laboratory (LANL), the U.S. Government retains certain rights in
// this software.
//
//=============================================================================
#ifndef vtk_m_worklet_ScatterCounting_h
#define vtk_m_worklet_ScatterCounting_h
#include <vtkm/cont/Algorithm.h>
#include <vtkm/cont/ArrayCopy.h>
#include <vtkm/cont/ArrayHandle.h>
#include <vtkm/cont/ArrayHandleCast.h>
#include <vtkm/cont/ArrayHandleConcatenate.h>
#include <vtkm/cont/ArrayHandleConstant.h>
#include <vtkm/cont/ArrayHandleIndex.h>
#include <vtkm/cont/ArrayHandleView.h>
#include <vtkm/cont/ErrorBadValue.h>
#include <vtkm/exec/FunctorBase.h>
#include <vtkm/worklet/DispatcherMapField.h>
#include <vtkm/worklet/WorkletMapField.h>
#include <sstream>
namespace vtkm
{
namespace worklet
{
namespace detail
{
VTKM_CONT
inline vtkm::cont::ArrayHandleConcatenate<
vtkm::cont::ArrayHandleConstant<vtkm::Id>,
vtkm::cont::ArrayHandleView<vtkm::cont::ArrayHandle<vtkm::Id>>>
ShiftArrayHandleByOne(const vtkm::cont::ArrayHandle<vtkm::Id>& array)
{
return vtkm::cont::make_ArrayHandleConcatenate(
vtkm::cont::make_ArrayHandleConstant<vtkm::Id>(0, 1),
vtkm::cont::make_ArrayHandleView(array, 0, array.GetNumberOfValues() - 1));
}
struct ReverseInputToOutputMapWorklet : vtkm::worklet::WorkletMapField
{
using ControlSignature = void(FieldIn<IdType> outputStartIndices,
FieldIn<IdType> outputEndIndices,
WholeArrayOut<IdType> outputToInputMap,
WholeArrayOut<IdComponentType> visit);
using ExecutionSignature = void(_1, _2, _3, _4, InputIndex);
using InputDomain = _2;
template <typename OutputMapType, typename VisitType>
VTKM_EXEC void operator()(vtkm::Id outputStartIndex,
vtkm::Id outputEndIndex,
const OutputMapType& outputToInputMap,
const VisitType& visit,
vtkm::Id inputIndex) const
{
vtkm::IdComponent visitIndex = 0;
for (vtkm::Id outputIndex = outputStartIndex; outputIndex < outputEndIndex; outputIndex++)
{
outputToInputMap.Set(outputIndex, inputIndex);
visit.Set(outputIndex, visitIndex);
visitIndex++;
}
}
VTKM_CONT
static void Run(const vtkm::cont::ArrayHandle<vtkm::Id>& inputToOutputMap,
const vtkm::cont::ArrayHandle<vtkm::Id>& outputToInputMap,
const vtkm::cont::ArrayHandle<vtkm::IdComponent>& visit,
vtkm::cont::DeviceAdapterId device)
{
vtkm::worklet::DispatcherMapField<ReverseInputToOutputMapWorklet> dispatcher;
dispatcher.SetDevice(device);
dispatcher.Invoke(
ShiftArrayHandleByOne(inputToOutputMap), inputToOutputMap, outputToInputMap, visit);
}
};
struct SubtractToVisitIndexWorklet : vtkm::worklet::WorkletMapField
{
using ControlSignature = void(FieldIn<IdType> startsOfGroup,
WholeArrayOut<IdComponentType> visit);
using ExecutionSignature = void(InputIndex, _1, _2);
using InputDomain = _1;
template <typename VisitType>
VTKM_EXEC void operator()(vtkm::Id inputIndex,
vtkm::Id startOfGroup,
const VisitType& visit) const
{
vtkm::IdComponent visitIndex = static_cast<vtkm::IdComponent>(inputIndex - startOfGroup);
visit.Set(inputIndex, visitIndex);
}
};
} // namespace detail
/// \brief A scatter that maps input to some numbers of output.
///
/// The \c Scatter classes are responsible for defining how much output is
/// generated based on some sized input. \c ScatterCounting establishes a 1 to
/// N mapping from input to output. That is, every input element generates 0 or
/// more output elements associated with it. The output elements are grouped by
/// the input associated.
///
/// A counting scatter takes an array of counts for each input. The data is
/// taken in the constructor and the index arrays are derived from that. So
/// changing the counts after the scatter is created will have no effect.
///
struct ScatterCounting
{
/// Construct a \c ScatterCounting object using an array of counts for the
/// number of outputs for each input. Part of the construction requires
/// generating an input to output map, but this map is not needed for the
/// operations of \c ScatterCounting, so by default it is deleted. However,
/// other users might make use of it, so you can instruct the constructor
/// to save the input to output map.
///
template <typename CountArrayType>
VTKM_CONT ScatterCounting(const CountArrayType& countArray,
vtkm::cont::DeviceAdapterId device = vtkm::cont::DeviceAdapterTagAny(),
bool saveInputToOutputMap = false)
{
this->BuildArrays(countArray, device, saveInputToOutputMap);
}
template <typename CountArrayType>
VTKM_CONT ScatterCounting(const CountArrayType& countArray, bool saveInputToOutputMap)
{
this->BuildArrays(countArray, vtkm::cont::DeviceAdapterTagAny(), saveInputToOutputMap);
}
using OutputToInputMapType = vtkm::cont::ArrayHandle<vtkm::Id>;
template <typename RangeType>
VTKM_CONT OutputToInputMapType GetOutputToInputMap(RangeType) const
{
return this->OutputToInputMap;
}
using VisitArrayType = vtkm::cont::ArrayHandle<vtkm::IdComponent>;
template <typename RangeType>
VTKM_CONT VisitArrayType GetVisitArray(RangeType) const
{
return this->VisitArray;
}
VTKM_CONT
vtkm::Id GetOutputRange(vtkm::Id inputRange) const
{
if (inputRange != this->InputRange)
{
std::stringstream msg;
msg << "ScatterCounting initialized with input domain of size " << this->InputRange
<< " but used with a worklet invoke of size " << inputRange << std::endl;
throw vtkm::cont::ErrorBadValue(msg.str());
}
return this->VisitArray.GetNumberOfValues();
}
VTKM_CONT
vtkm::Id GetOutputRange(vtkm::Id3 inputRange) const
{
return this->GetOutputRange(inputRange[0] * inputRange[1] * inputRange[2]);
}
VTKM_CONT
OutputToInputMapType GetOutputToInputMap() const { return this->OutputToInputMap; }
/// This array will not be valid unless explicitly instructed to be saved.
/// (See documentation for the constructor.)
///
VTKM_CONT
vtkm::cont::ArrayHandle<vtkm::Id> GetInputToOutputMap() const { return this->InputToOutputMap; }
private:
vtkm::Id InputRange;
vtkm::cont::ArrayHandle<vtkm::Id> InputToOutputMap;
OutputToInputMapType OutputToInputMap;
VisitArrayType VisitArray;
template <typename CountArrayType>
VTKM_CONT void BuildArrays(const CountArrayType& count,
vtkm::cont::DeviceAdapterId device,
bool saveInputToOutputMap)
{
VTKM_IS_ARRAY_HANDLE(CountArrayType);
this->InputRange = count.GetNumberOfValues();
// The input to output map is actually built off by one. The first entry
// is actually for the second value. The last entry is the total number of
// output. This off-by-one is so that an upper bound find will work when
// building the output to input map. Later we will either correct the
// map or delete it.
vtkm::cont::ArrayHandle<vtkm::Id> inputToOutputMapOffByOne;
vtkm::Id outputSize = vtkm::cont::Algorithm::ScanInclusive(
device, vtkm::cont::make_ArrayHandleCast(count, vtkm::Id()), inputToOutputMapOffByOne);
// We have implemented two different ways to compute the output to input
// map. The first way is to use a binary search on each output index into
// the input map. The second way is to schedule on each input and
// iteratively fill all the output indices for that input. The first way is
// faster for output sizes that are small relative to the input (typical in
// Marching Cubes, for example) and also tends to be well load balanced.
// The second way is faster for larger outputs (typical in triangulation,
// for example). We will use the first method for small output sizes and
// the second for large output sizes. Toying with this might be a good
// place for optimization.
if (outputSize < this->InputRange)
{
this->BuildOutputToInputMapWithFind(outputSize, device, inputToOutputMapOffByOne);
}
else
{
this->BuildOutputToInputMapWithIterate(outputSize, device, inputToOutputMapOffByOne);
}
if (saveInputToOutputMap)
{
// Since we are saving it, correct the input to output map.
vtkm::cont::Algorithm::Copy(
device, detail::ShiftArrayHandleByOne(inputToOutputMapOffByOne), this->InputToOutputMap);
}
}
VTKM_CONT void BuildOutputToInputMapWithFind(
vtkm::Id outputSize,
vtkm::cont::DeviceAdapterId device,
vtkm::cont::ArrayHandle<vtkm::Id> inputToOutputMapOffByOne)
{
vtkm::cont::ArrayHandleIndex outputIndices(outputSize);
vtkm::cont::Algorithm::UpperBounds(
device, inputToOutputMapOffByOne, outputIndices, this->OutputToInputMap);
vtkm::cont::ArrayHandle<vtkm::Id> startsOfGroups;
// This find gives the index of the start of a group.
vtkm::cont::Algorithm::LowerBounds(
device, this->OutputToInputMap, this->OutputToInputMap, startsOfGroups);
this->VisitArray.Allocate(outputSize);
vtkm::worklet::DispatcherMapField<detail::SubtractToVisitIndexWorklet> dispatcher;
dispatcher.SetDevice(device);
dispatcher.Invoke(startsOfGroups, this->VisitArray);
}
VTKM_CONT void BuildOutputToInputMapWithIterate(
vtkm::Id outputSize,
vtkm::cont::DeviceAdapterId device,
vtkm::cont::ArrayHandle<vtkm::Id> inputToOutputMapOffByOne)
{
this->OutputToInputMap.Allocate(outputSize);
this->VisitArray.Allocate(outputSize);
detail::ReverseInputToOutputMapWorklet::Run(
inputToOutputMapOffByOne, this->OutputToInputMap, this->VisitArray, device);
}
};
}
} // namespace vtkm::worklet
#endif //vtk_m_worklet_ScatterCounting_h