fixedpoint_tensor.h

// Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <vector>

#include "circuit_context.h"
#include "paddle_tensor.h"
#include "boolean_tensor.h"
#include "core/paddlefl_mpc/mpc_protocol/context_holder.h"

namespace aby3 {

template<typename T, size_t N>
class FixedPointTensor {

public:
    explicit FixedPointTensor(TensorAdapter<T>* share_tensor[2]);

    explicit FixedPointTensor(TensorAdapter<T>* share_tensor_0,
                              TensorAdapter<T>* share_tensor_1);

    ~FixedPointTensor() {};

    //get mutable shape of tensor
    TensorAdapter<T>* mutable_share(size_t idx);

    const TensorAdapter<T>* share(size_t idx) const;

    size_t numel() const {
        return _share[0]->numel();
    }

    // reveal fixedpointtensor to one party
    void reveal_to_one(size_t party, TensorAdapter<T>* ret) const;

    // reveal fixedpointtensor to all parties
    void reveal(TensorAdapter<T>* ret) const;

    const std::vector<size_t> shape() const;

    //convert TensorAdapter to shares
    static void share(const TensorAdapter<T>* input,
                      TensorAdapter<T>* output_shares[3],
                      block seed = g_zero_block);

    // element-wise add with FixedPointTensor
    void add(const FixedPointTensor* rhs, FixedPointTensor* ret) const;

    // element-wise add with TensorAdapter

    void add(const TensorAdapter<T>* rhs, FixedPointTensor* ret) const;

    // element-wise sub with FixedPointTensor
    void sub(const FixedPointTensor* rhs, FixedPointTensor* ret) const;

    // element-wise sub with TensorAdapter
    void sub(const TensorAdapter<T>* rhs, FixedPointTensor* ret) const;

    // negative
    void negative(FixedPointTensor* ret) const;

    // element-wise mul with FixedPointTensor using truncate1
    void mul(const FixedPointTensor* rhs, FixedPointTensor* ret) const;

    // element-wise mul with TensorAdapter
    void mul(const TensorAdapter<T>* rhs, FixedPointTensor* ret) const;

    // div by TensorAdapter
    void div(const TensorAdapter<T>* rhs, FixedPointTensor* ret) const;

    // div by FixedPointedTensor
    // TODO@yqy : not surport operator rhs <= 0 now
    void div(const FixedPointTensor* rhs, FixedPointTensor* ret,
             size_t iter = 16, double x0 = pow(2, -15)) const;

    // long div by boolean circuit
    // res_int_len: estimated bit len of the integer part of result
    void long_div(const FixedPointTensor* rhs,
                  FixedPointTensor* ret, size_t res_int_len = 20) const;

    void inverse_square_root(FixedPointTensor* ret,
                             size_t iter = 16, double x0 = 0x1p-10) const;

    // dot_mul
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void dot_mul(const CTensor<T, N1...>* rhs, FixedPointTensor* ret) const;

    //sum all element
    void sum(FixedPointTensor* ret) const;

    // mat_mul with FixedPointTensor
    void mat_mul(const FixedPointTensor* rhs, FixedPointTensor* ret) const;

    // mat_mul with TensorAdapter
    void mat_mul(const TensorAdapter<T>* rhs, FixedPointTensor* ret) const;

    // exp approximate: exp(x) = \lim_{n->inf} (1+x/n)^n
    // where n = 2^ite
    void exp(FixedPointTensor* ret, size_t iter = 8) const;

    // element-wise relu
    void relu(FixedPointTensor* ret) const;

    // element-wise relu with relu'
    void relu_with_derivative(FixedPointTensor* ret, BooleanTensor<T>* derivative) const;

    // element-wise sigmoid using 3 piecewise polynomials
    void sigmoid(FixedPointTensor* ret) const;

    // element-wise sigmoid using 5 pieces polynomial
    // see paper [Privacy-preserving collaborative machine learning
    //            on genomic data using TensorFlow]
    void sigmoid_enhanced(FixedPointTensor* ret) const;

    // element-wise sigmoid using Chebyshev polynomial approximation
    // implemented with ref to tfe[https://github.com/tf-encrypted/tf-encrypted]
    void sigmoid_chebyshev(FixedPointTensor* ret) const;

    // softmax axis = -1
    void softmax(FixedPointTensor* ret,
                 bool use_relu = false,
                 bool use_long_div = true) const;

    // element-wise polynomial
    void polynomial(const TensorAdapter<T>* coeff,
                    FixedPointTensor* ret) const;

    // element-wise piecewise polynomial
    void polynomial_piecewise(
                const TensorAdapter<T>* coeff,
                const TensorAdapter<T>* break_point,
                FixedPointTensor* ret) const;

    // element-wise compare
    // <
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void lt(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // <=
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void leq(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // >
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void gt(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // >=
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void geq(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // ==
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void eq(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // !=
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void neq(const CTensor<T, N1...>* rhs, BooleanTensor<T>* ret) const;

    // element-wise max
    // if not null, cmp stores true if rhs is bigger
    template<template<typename U, size_t...> class CTensor,
            size_t... N1>
    void max(const CTensor<T, N1...>* rhs,
             FixedPointTensor* ret,
             BooleanTensor<T>* cmp = nullptr) const;

    // for tensor with shape like [k, n, m, ...]
    // ret shape is [1, n, m, ...], in which every element is largest of k elements
    // pos shape is [k, n, m, ...], each col of pos is an one-hot tensor
    // which indicating the max element's position
    void max_pooling(FixedPointTensor* ret,
                     BooleanTensor<T>* pos = nullptr) const;

    static void truncate(const FixedPointTensor* op, FixedPointTensor* ret,
                        size_t scaling_factor);

private:

    static inline std::shared_ptr<CircuitContext> aby3_ctx() {
        return paddle::mpc::ContextHolder::mpc_ctx();
    }

    static inline std::shared_ptr<TensorAdapterFactory> tensor_factory() {
        return paddle::mpc::ContextHolder::tensor_factory();
    }

    template<typename MulFunc>
    static void mul_trunc(const FixedPointTensor<T, N>* lhs,
                          const FixedPointTensor<T, N>* rhs,
                          FixedPointTensor<T, N>* ret,
                          MulFunc mul_func);

    // truncate3 protocol can avoid losing msb error when truncate
    // with acceptable security compromise
    static void truncate3(const FixedPointTensor* op, FixedPointTensor* ret,
                          size_t scaling_factor);

    // reduce last dim
    static void reduce(FixedPointTensor<T, N>* input,
                       FixedPointTensor<T, N>* ret);

    static size_t party() {
        return aby3_ctx()->party();
    }

    static size_t pre_party() {
        return aby3_ctx()->pre_party();
    }

    static size_t next_party() {
        return aby3_ctx()->next_party();
    }

    static void reshare(const TensorAdapter<T>* send_val,
                 TensorAdapter<T>* recv_val) {
        if (party() == 0) {
            aby3_ctx()->network()->template recv(next_party(), *recv_val);
            aby3_ctx()->network()->template send(pre_party(), *send_val);
        } else {
            aby3_ctx()->network()->template send(pre_party(), *send_val);
            aby3_ctx()->network()->template recv(next_party(), *recv_val);
        }
    }

    static void reciprocal(const FixedPointTensor* op, FixedPointTensor* ret,
                                                      size_t iter, double x0);

    static void inverse_square_root(const FixedPointTensor* op,
                                    FixedPointTensor* ret,
                                    size_t iter, double x0);

    TensorAdapter<T>* _share[2];

};

} //namespace aby3

#include "fixedpoint_tensor_imp.h"