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99ce66c6fe
Previously, all Fetch objects received an Invocation object in their Load and Store methods. The point of this was that it allowed the Fetch to get data from any of the execution objects. However, every Fetch either just got data directly from its associated execution object or else used a secondary execution object (the input domain) to get indices into their own execution object. This left two potential areas for improvement. First, pulling data out of the Invocation object was unnecessarily complicated. It would be much nicer to get data directly from the associated execution object. Second, when getting index information from the input domain, it was often the case that extra computations were necessary (particularly on structured cell sets). There was no way to share the index information among Fetches, and therefore the computations were replicated. This change removes the Invocation from the Fetch Load and Store. Instead, it passes the associated execution object and a new object type called the ThreadIndices. The ThreadIndices are customized for the input domain and therefore have all the information needed for a redirected lookup. It is also a thread-local object so it can cache computed indices and save on computation time.
105 lines
4.3 KiB
C++
105 lines
4.3 KiB
C++
//============================================================================
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// Copyright (c) Kitware, Inc.
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// All rights reserved.
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// See LICENSE.txt for details.
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// This software is distributed WITHOUT ANY WARRANTY; without even
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// the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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// PURPOSE. See the above copyright notice for more information.
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//
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// Copyright 2014 Sandia Corporation.
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// Copyright 2014 UT-Battelle, LLC.
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// Copyright 2014 Los Alamos National Security.
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//
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// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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// the U.S. Government retains certain rights in this software.
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//
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// Under the terms of Contract DE-AC52-06NA25396 with Los Alamos National
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// Laboratory (LANL), the U.S. Government retains certain rights in
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// this software.
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//============================================================================
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#ifndef vtk_m_exec_arg_Fetch_h
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#define vtk_m_exec_arg_Fetch_h
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#include <vtkm/Types.h>
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namespace vtkm {
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namespace exec {
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namespace arg {
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/// \brief Class for loading and storing values in thread instance.
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///
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/// The \c Fetch class is used within a thread in the execution environment
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/// to load a value from an execution object specific for the given thread
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/// instance and to store a resulting value back in the object. (Either load
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/// or store can be a no-op.)
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///
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/// \c Fetch is a templated class with four arguments. The first argument is a
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/// tag declaring the type of fetch, which is usually tied to a particular type
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/// of execution object. The second argument is an aspect tag that declares
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/// what type of data to pull/push. Together, these two tags determine the
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/// mechanism for the fetch. The third argument is the type of thread indices
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/// used (one of the classes that starts with \c ThreadIndices in the
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/// vtkm::exec::arg namespace), which defines the type of thread-local indices
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/// available during the fetch. The fourth argument is the type of execution
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/// object associated where the fetch (nominally) gets its data from. This
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/// execution object is the data provided by the transport.
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///
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/// There is no generic implementaiton of \c Fetch. There are partial
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/// specializations of \c Fetch for each mechanism (fetch-aspect tag
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/// combination) supported. If you get a compiler error about an incomplete
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/// type for \c Fetch, it means you used an invalid \c FetchTag - \c AspectTag
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/// combination. Most likely this means that a parameter in an
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/// ExecutionSignature with a particular aspect is pointing to the wrong
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/// argument or an invalid argument in the ControlSignature.
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///
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template<typename FetchTag,
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typename AspectTag,
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typename ThreadIndicesType,
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typename ExecObjectType>
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struct Fetch
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#ifdef VTKM_DOXYGEN_ONLY
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{
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/// \brief The type of value to load and store.
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///
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/// All \c Fetch specializations are expected to declare a type named \c
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/// ValueType that is the type of object returned from \c Load and passed to
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/// \c Store.
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///
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typedef typename ExecObjectType::ValueType ValueType;
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/// \brief Load data for a work instance.
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///
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/// All \c Fetch specializations are expected to have a constant method named
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/// \c Load that takes a \c ThreadIndices object containing thread-local
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/// indices and an execution object and returns the value appropriate for the
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/// work instance. If there is no actual data to load (for example for a
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/// write-only fetch), this method can be a no-op and return any value.
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///
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VTKM_EXEC_EXPORT
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ValueType Load(const ThreadIndicesType &indices,
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const ExecObjectType &execObject) const;
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/// \brief Store data from a work instance.
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///
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/// All \c Fetch specializations are expected to have a constant method named
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/// \c Store that takes a \c ThreadIndices object containing thread-local
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/// indices, an execution object, and a value computed by the worklet call
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/// and stores that value into the execution object associated with this
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/// fetch. If the store is not applicable (for example for a read-only
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/// fetch), this method can be a no-op.
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///
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VTKM_EXEC_EXPORT
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void Store(const ThreadIndicesType &indices,
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const ExecObjectType &execObject,
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const ValueType &value) const;
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};
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#else // VTKM_DOXYGEN_ONLY
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;
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#endif // VTKM_DOXYGEN_ONLY
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}
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}
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} // namespace vtkm::exec::arg
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#endif //vtk_m_exec_arg_Fetch_h
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