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136 lines
3.8 KiB
136 lines
3.8 KiB
/* Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserve.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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 "CrossEntropyOverBeam.h"
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#include "Layer.h"
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namespace paddle {
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/* This struct stores the beams in all search steps for a single sequence. */
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struct BeamExpansion {
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std::vector<MatrixPtr> scores;
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std::vector<IVectorPtr> seqInfo;
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std::vector<MatrixPtr> candidateIds;
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std::vector<int> gold;
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std::vector<MatrixPtr> scoreGrad;
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size_t expansionCount;
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explicit BeamExpansion(int n) {
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expansionCount = n;
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scores.resize(expansionCount);
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seqInfo.resize(expansionCount);
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candidateIds.resize(expansionCount);
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scoreGrad.resize(expansionCount);
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gold.resize(expansionCount);
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}
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};
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typedef std::shared_ptr<BeamExpansion> BeamExpansionPtr;
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class CostForOneSequence {
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public:
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CostForOneSequence()
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: beamSize_(0), validExpansionCount_(0), goldAsExtraPath_(false) {}
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void setData(const BeamExpansionPtr bPtr, size_t beamSize) {
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beams_ = bPtr;
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beamSize_ = beamSize;
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expandedPathScores_.clear();
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expandedPathScores_.resize(beams_->expansionCount);
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goldRowIds_.clear();
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goldRowIds_.resize(beams_->expansionCount, 0);
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goldColIds_.clear();
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goldColIds_.resize(beams_->expansionCount, -1);
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}
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size_t getValidExpansionCount() { return validExpansionCount_; }
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real forward();
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void backward();
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private:
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void calValidExpandStep();
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void constructTotalExpansion();
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size_t initLastExpansion();
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real globallyNormalizedScore();
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int getSeqStartPos(size_t beamId, size_t rowId) {
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CHECK_GT(beams_->seqInfo[beamId]->getSize() - 1, rowId);
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int* starts = beams_->seqInfo[beamId]->getData();
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return starts[rowId] - starts[0];
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}
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size_t beamSize_;
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size_t validExpansionCount_;
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bool goldAsExtraPath_;
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std::vector<int> goldRowIds_;
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std::vector<int> goldColIds_;
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BeamExpansionPtr beams_;
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std::vector<std::vector<int>> pathRowIdsInEachBeam_;
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std::vector<int> parentIdsInBeam_;
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size_t goldIdsInFinalExpansion_;
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std::vector<MatrixPtr> expandedPathScores_;
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MatrixPtr softmaxOut_;
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};
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class CrossEntropyOverBeam : public Layer {
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public:
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explicit CrossEntropyOverBeam(const LayerConfig& config) : Layer(config) {}
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bool init(const LayerMap& layerMap,
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const ParameterMap& parameterMap) override;
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void forward(PassType passType) override;
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void backward(const UpdateCallback& callback) override;
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private:
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void checkInputs();
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void copyInputsToCpu();
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void resizeOutput();
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void copyGradToGpu(size_t copyCount);
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void splitBatchBeams();
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size_t beamExpanCount_;
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size_t batchSize_;
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size_t beamSize_;
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/*
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* the process of constructing beams is not friendly to GPU, currently, this
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* layer only runs on CPU, if any of its inputs is on GPU memory, then copy
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* it to CPU memory.
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*/
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std::vector<MatrixPtr> candidateScores_;
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std::vector<MatrixPtr> candidateScoreGrad_;
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std::vector<MatrixPtr> candidateInBeam_;
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std::vector<MatrixPtr> gradToInputs_;
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std::vector<IVectorPtr> goldSequence_;
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std::vector<std::vector<int>> beamSplitPos_;
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/*
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* split entire bath of beams into beam per sequnence and store the result
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* into this member.
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*/
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std::vector<BeamExpansion> beamPerSeq_;
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/* beamCosts_ is used to propagate error in one sequence. */
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std::vector<CostForOneSequence> beamCosts_;
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};
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} // namespace paddle
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