wehub-resource-sync
82 lines
2.9 KiB
C++
82 lines
2.9 KiB
C++
// Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <functional>
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#include <memory>
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#include <utility>
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#include <vector>
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namespace paddle {
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namespace imperative {
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class VariableWrapper;
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/** [ VariableWrapper Hook ]
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*
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* @brief This hook functor is executed before the grad OpBase is executed or
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* after gradient accumulation completed in current batch.
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* 1. For interior var, VariableWrapper Hook take the input of the
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* current grad OpBase as input.
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* 2. For leaf var, VariableWrapper Hook take the inner_var_ of
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* GradientAccumulator as input.
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*
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* @note This hook functor will not change the input gradient VariableWrapper,
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* but if you copy the input VariableWrapper and change the value of
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* Variable in VariableWrapper, the value of input will also be changed,
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* because they shared same PlaceHolder.
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*
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* @note [ Why need to be OpBase `PreHook`, why not `PostHook`? ]
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*
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* We expect If set OpBase post hook, when the op executed end, the
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* op's output gradient may not be the final state, because it may need
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* other op's gradient output to accumulated to it. But before op can
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* be executed, the gradient output must have been accumulated to final
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* value.
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*
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* @note [ Why Leaf gradient is special? ]
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*
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* Because the leaf VarBase's GradVarBase has no GradOpNode, so leaf
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* GradVarBase has no next OpBase to executed, so if need to deal with
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* the leaf GradVarBase, we should call hooks after gradient accumulation
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* completed.
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*/
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class VariableWrapperHook {
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public:
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virtual ~VariableWrapperHook() = default;
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virtual std::shared_ptr<VariableWrapper> operator()(
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const std::shared_ptr<VariableWrapper>& var) = 0;
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};
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class CppVariableWrapperHook : public VariableWrapperHook {
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public:
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explicit CppVariableWrapperHook(
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std::function<std::shared_ptr<VariableWrapper>(
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const std::shared_ptr<VariableWrapper>&)>&& fn)
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: fn_(std::move(fn)) {}
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std::shared_ptr<VariableWrapper> operator()(
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const std::shared_ptr<VariableWrapper>& var) override {
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return fn_(var);
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}
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private:
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std::function<std::shared_ptr<VariableWrapper>(
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const std::shared_ptr<VariableWrapper>&)>
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fn_;
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};
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} // namespace imperative
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} // namespace paddle
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