// Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
// Copyright (c) 2022 NVIDIA 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 <memory>
#include <string>
#include <unordered_set>
#include <utility>
#include <vector>

#include "paddle/fluid/framework/ir/pass_builder.h"
#include "paddle/fluid/framework/program_desc.h"
#include "paddle/fluid/framework/scope.h"
#include "paddle/fluid/platform/device_context.h"
#include "paddle/fluid/platform/enforce.h"

namespace paddle {
namespace framework {
namespace ir {
class Graph;
class PassBuilder;
}  // namespace ir
}  // namespace framework
namespace platform {
class NCCLCommunicator;
}  // namespace platform
}  // namespace paddle

#if defined(PADDLE_WITH_NCCL) || defined(PADDLE_WITH_RCCL)
#include "paddle/fluid/platform/device/gpu/nccl_helper.h"
#elif defined(PADDLE_WITH_XPU) && defined(PADDLE_WITH_XPU_BKCL)
#include "paddle/fluid/platform/device/xpu/bkcl_helper.h"
#endif

namespace paddle {
namespace framework {
namespace details {
using DeviceType = paddle::platform::DeviceType;
namespace p = paddle::platform;

struct BuildStrategy {
  // ParallelExecutor supports two modes of ReduceStrategy, kAllReduce and
  // kReduce, for CPU and GPU. If you use kAllReduce, different threads
  // optimize their parameters separately. If you use kReduce, the optimizations
  // of parameters are distributed to different threads.
  // For example, a model has 100 parameters and is running with four threads,
  // if you choose kAllReduce, every thread is to optimize 100 parameters
  // separately, if you choose kReduce, every thread is to optimize 25
  // parameters.
  // Of particular note is, if you use kReduce when using CPU training,
  // all the parameters are shared between different threads. This
  // feature will save memory.
  // FIXME(zcd): The result of the two modes(kAllReduce and kReduce) maybe not
  // equal for GPU. Because, the result of the different order of summing maybe
  // different, for example, the result of `a+b+c+d` may be different with the
  // result of `c+a+b+d`.
  // For GPU, the implementation of kAllReduce and kReduce is adopted NCCL,
  // so the result of kAllReduce and kReduce maybe not equal.
  // For CPU, if you want to fix the order of summing to make the result
  // of kAllReduce and kReduce no diff, you can add
  // `FLAGS_cpu_deterministic=true` to env.
  enum class ReduceStrategy { kAllReduce = 0, kReduce = 1, kNoReduce = 2 };

  enum class GradientScaleStrategy {
    kCoeffNumDevice = 0,
    kOne = 1,
    // user can customize gradient scale to use, and just feed
    // it into exe.run().
    kCustomized = 2,
  };

  ReduceStrategy reduce_{ReduceStrategy::kAllReduce};
  GradientScaleStrategy gradient_scale_{GradientScaleStrategy::kCoeffNumDevice};

  std::string debug_graphviz_path_{""};

  // Add dependency between backward ops and optimization ops, make sure that
  // all the backward ops are finished before running the optimization
  // ops. It might make the training speed of data parallelism faster.
  bool enable_backward_optimizer_op_deps_{true};
  // TODO(dev-paddle): enable_sequential_execution depends on
  // kStaleProgramOpDescs, it is not appropriate, because kStaleProgramOpDescs
  // will be removed in the near future.
  bool enable_sequential_execution_{false};
  bool remove_unnecessary_lock_{true};
  // TODO(dev-paddle): cache_runtime_context may cause some models to hang up
  // while running.
  bool cache_runtime_context_{false};

  // Fix the op run order.
  bool fix_op_run_order_{false};

  // Lowering sub-graph into cinn ops.
  bool build_cinn_pass_{false};

  // Operator fusion
  // TODO(dev-paddle): fuse_elewise_add_act_ops may cause some models have
  // cycle.
  bool fuse_bn_act_ops_{false};
  bool fuse_bn_add_act_ops_{true};
  bool fuse_elewise_add_act_ops_{false};
  bool enable_auto_fusion_{false};
  // Fuse_all_optimizer_ops and fuse_all_reduce_ops require that gradients
  // should not be sparse types
  paddle::optional<bool> fuse_all_optimizer_ops_{false};
  paddle::optional<bool> fuse_all_reduce_ops_{paddle::none};
  // fuse_relu_depthwise_conv can fuse the `relu ->
  // depthwise_conv`
  bool fuse_relu_depthwise_conv_{false};
  // NOTE(zcd): In reduce mode, fusing broadcast ops may make the program
  // faster. Because fusing broadcast OP equals delaying the execution of all
  // broadcast Ops, in this case, all nccl streams are used only for reduce
  // operations for a period of time.
  paddle::optional<bool> fuse_broadcast_ops_{paddle::none};
  // replace batch_norm with sync_batch_norm.
  bool sync_batch_norm_{false};
  // Fuse GEMM+Epilogue via cublasLt epilogue.
  bool fuse_gemm_epilogue_{false};

  // mkldnn_enabled_op_types specify the operator type list to
  // use MKLDNN acceleration. It is null in default, means
  // that all the operators supported by MKLDNN will be
  // accelerated. And it should not be set when
  // FLAGS_use_mkldnn=false
  std::unordered_set<std::string> mkldnn_enabled_op_types_;

  // By default, memory_optimize would be opened if gc is disabled, and
  // be closed if gc is enabled.
  // Users can forcely enable/disable memory_optimize by setting True/False.
  paddle::optional<bool> memory_optimize_{paddle::none};

  // Turn on inplace by default.
  bool enable_inplace_{true};

  // Turn off inplace addto by default.
  bool enable_addto_{false};

  bool allow_cuda_graph_capture_{false};

  // Inference pass
  bool enable_inference_pass_{false};  // switch for infernce pass
  bool delete_dropout_{true};          // delte dropout op
#ifdef PADDLE_WITH_MKLDNN
  bool use_mkldnn_{true};  // use mkdnn to do inference
#else
  bool use_mkldnn_{false};  // use mkdnn to do inference
#endif

  // FIXME(zcd): is_distribution_ is a temporary field, because in pserver mode,
  // num_trainers is 1, so the current fields of build_strategy doesn't tell if
  // it's distributed model.
  bool is_distribution_{false};
  bool async_mode_{false};
  int num_trainers_{1};
  int trainer_id_{0};
  std::vector<std::string> trainers_endpoints_;

  // NCCL config
  size_t nccl_comm_num_{1};
  size_t bkcl_comm_num_{1};
  // The picture is here:
  // https://github.com/PaddlePaddle/Paddle/pull/17263#discussion_r285411396
  bool use_hierarchical_allreduce_{false};
  // Nccl ranks in a node when use hierarchical allreduce, it's set to gpu
  // cards' number in most cases.
  size_t hierarchical_allreduce_inter_nranks_{0};
  // Nccl ranks bewteen nodes when use hierarchical allreduce, it's set to
  // nodes number.
  size_t hierarchical_allreduce_exter_nranks_{0};

  // NOTE:
  // Before you add new options, think if it's a general strategy that works
  // with other strategy. If not, the strategy should be created through
  // CreatePassesFromStrategy and the pass can be managed separately.

  // User normally doesn't need to call this API.
  // The PassBuilder allows for more customized insert, remove of passes
  // from python side.
  // A new PassBuilder is created based on configs defined above and
  // passes are owned by the PassBuilder.
  std::shared_ptr<ir::PassBuilder> CreatePassesFromStrategy(
      bool finalize_strategy) const;

  bool IsFinalized() const { return is_finalized_; }

  void ClearFinalized() {
    pass_builder_ = nullptr;
    is_finalized_ = false;
  }

  bool IsMultiDevPass(const std::string &pass_name) const;

  // Apply the passes built by the pass_builder_. The passes will be
  // applied to the Program and output an ir::Graph.
  ir::Graph *Apply(ir::Graph *graph,
                   const std::vector<platform::Place> &places,
                   const std::string &loss_var_name,
                   const std::vector<Scope *> &local_scopes,
                   const size_t &nranks,
#if defined(PADDLE_WITH_NCCL) || defined(PADDLE_WITH_RCCL)
                   DeviceType use_device,
                   platform::NCCLCommunicator *nccl_ctxs) const;
#elif defined(PADDLE_WITH_XPU) && defined(PADDLE_WITH_XPU_BKCL)
                   DeviceType use_device,
                   platform::BKCLCommunicator *bkcl_ctxs) const;
#else
                   DeviceType use_device) const;
#endif

  // If set true, ParallelExecutor would build the main_program into multiple
  // graphs,
  // each of the graphs would run with one device. This approach can achieve
  // better performance
  // on some scenarios.
  mutable bool enable_parallel_graph_ = false;

 private:
  mutable bool is_finalized_ = false;
  mutable std::shared_ptr<ir::PassBuilder> pass_builder_;
};

inline std::ostream &operator<<(std::ostream &os,
                                const BuildStrategy &strategy) {
  os << "BuildStrategy: " << &strategy << std::endl;
  os << "reduce_: " << static_cast<int>(strategy.reduce_) << std::endl;
  os << "gradient_scale_: " << static_cast<int>(strategy.gradient_scale_)
     << std::endl;
  os << "debug_graphviz_path_: " << strategy.debug_graphviz_path_ << std::endl;
  os << "enable_backward_optimizer_op_deps_: "
     << strategy.enable_backward_optimizer_op_deps_ << std::endl;
  os << "enable_sequential_execution_: "
     << strategy.enable_sequential_execution_ << std::endl;
  os << "remove_unnecessary_lock_: " << strategy.remove_unnecessary_lock_
     << std::endl;
  os << "cache_runtime_context_: " << strategy.cache_runtime_context_
     << std::endl;
  os << "fix_op_run_order_: " << strategy.fix_op_run_order_ << std::endl;
  os << "fuse_bn_act_ops_: " << strategy.fuse_bn_act_ops_ << std::endl;
  os << "fuse_bn_add_act_ops_: " << strategy.fuse_bn_add_act_ops_ << std::endl;
  os << "fuse_elewise_add_act_ops_: " << strategy.fuse_elewise_add_act_ops_
     << std::endl;
  os << "enable_auto_fusion_: " << strategy.enable_auto_fusion_ << std::endl;
  os << "fuse_all_optimizer_ops_: " << strategy.fuse_all_optimizer_ops_
     << std::endl;
  os << "fuse_all_reduce_ops_: " << strategy.fuse_all_reduce_ops_ << std::endl;
  os << "fuse_relu_depthwise_conv_: " << strategy.fuse_relu_depthwise_conv_
     << std::endl;
  os << "fuse_broadcast_ops_: " << strategy.fuse_broadcast_ops_ << std::endl;
  os << "sync_batch_norm_: " << strategy.sync_batch_norm_ << std::endl;
  os << "fuse_gemm_epilogue_: " << strategy.fuse_gemm_epilogue_ << std::endl;
  os << "mkldnn_enabled_op_types_: ";
  for (auto str : strategy.mkldnn_enabled_op_types_) {
    os << str << ", ";
  }
  os << std::endl;
  os << "memory_optimize_: " << strategy.memory_optimize_ << std::endl;
  os << "enable_inplace_: " << strategy.enable_inplace_ << std::endl;
  os << "allow_cuda_graph_capture_: " << strategy.allow_cuda_graph_capture_
     << std::endl;
  os << "enable_inference_pass_: " << strategy.enable_inference_pass_
     << std::endl;
  os << "delete_dropout_: " << strategy.delete_dropout_ << std::endl;
  os << "use_mkldnn_: " << strategy.use_mkldnn_ << std::endl;
  os << "is_distribution_: " << strategy.is_distribution_ << std::endl;
  os << "async_mode_: " << strategy.async_mode_ << std::endl;
  os << "num_trainers_: " << strategy.num_trainers_ << std::endl;
  os << "trainer_id_: " << strategy.trainer_id_ << std::endl;
  os << "trainers_endpoints_: ";
  for (auto str : strategy.trainers_endpoints_) {
    os << str << ", ";
  }
  os << std::endl;
  os << "nccl_comm_num_: " << strategy.nccl_comm_num_ << std::endl;
  os << "bkcl_comm_num_: " << strategy.bkcl_comm_num_ << std::endl;
  os << "use_hierarchical_allreduce_: " << strategy.use_hierarchical_allreduce_
     << std::endl;
  os << "hierarchical_allreduce_inter_nranks_: "
     << strategy.hierarchical_allreduce_inter_nranks_ << std::endl;
  os << "enable_parallel_graph_: " << strategy.enable_parallel_graph_
     << std::endl;
  return os;
}

}  // namespace details
}  // namespace framework
}  // namespace paddle