/* 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. */

#include <ostream>
#include <string>

#include "glog/logging.h"
#include "paddle/fluid/framework/op_proto_maker.h"
#include "paddle/fluid/framework/op_registry.h"
#include "paddle/fluid/framework/operator.h"
#include "paddle/fluid/framework/var_type_traits.h"
#include "paddle/fluid/platform/enforce.h"
#include "paddle/fluid/platform/gen_comm_id_helper.h"
#include "paddle/fluid/platform/nccl_helper.h"
#include "paddle/fluid/platform/place.h"

namespace paddle {
namespace framework {
class Scope;
}  // namespace framework
}  // namespace paddle

namespace paddle {
namespace operators {

static void GenNCCLID(std::vector<ncclUniqueId>* nccl_ids) {
  for (size_t i = 0; i < nccl_ids->size(); ++i) {
    PADDLE_ENFORCE_CUDA_SUCCESS(
        platform::dynload::ncclGetUniqueId(&(*nccl_ids)[i]));
  }
}

static void CopyNCCLIDToVar(const std::vector<ncclUniqueId>& nccl_ids,
                            std::function<std::string(size_t)> func,
                            const framework::Scope& scope) {
  for (size_t i = 0; i < nccl_ids.size(); ++i) {
    std::string var_name = func(i);
    auto var = scope.FindVar(var_name);
    PADDLE_ENFORCE_NOT_NULL(
        var, platform::errors::NotFound("Variable with name %s is not found",
                                        var_name.c_str()));
    auto nccl_id = var->GetMutable<ncclUniqueId>();
    memcpy(nccl_id, &nccl_ids[i], sizeof(ncclUniqueId));
  }
}

class GenNCCLIdOp : public framework::OperatorBase {
 public:
  GenNCCLIdOp(const std::string& type, const framework::VariableNameMap& inputs,
              const framework::VariableNameMap& outputs,
              const framework::AttributeMap& attrs)
      : OperatorBase(type, inputs, outputs, attrs) {}

  void RunImpl(const framework::Scope& scope,
               const platform::Place& dev_place) const override {
    std::vector<std::string> trainers =
        Attr<std::vector<std::string>>("trainers");
    int trainer_id = Attr<int>("trainer_id");
    std::string endpoint = trainers[trainer_id];

    PADDLE_ENFORCE_GE(trainer_id, 0, platform::errors::InvalidArgument(
                                         "trainer_id %d is less than 0. Its "
                                         "valid range is [0, trainer_size)"));
    PADDLE_ENFORCE_LT(
        trainer_id, static_cast<int>(trainers.size()),
        platform::errors::OutOfRange("trainer_id %d is out of range. Its valid "
                                     "range is [0, trainer_size)",
                                     trainer_id));

    int nccl_comm_num = Attr<int>("nccl_comm_num");
    int use_hierarchical_allreduce = Attr<bool>("use_hierarchical_allreduce");
    int inter_nranks = Attr<int>("hierarchical_allreduce_inter_nranks");
    int inter_trainer_id = -1;
    int exter_trainer_id = -1;

    if (use_hierarchical_allreduce) {
      PADDLE_ENFORCE_GT(
          trainers.size(), 1,
          platform::errors::PreconditionNotMet(
              "The number of collective trainers %llu <= 1", trainers.size()));
      PADDLE_ENFORCE_GT(
          inter_nranks, 1,
          platform::errors::PreconditionNotMet(
              "inter_nranks %d <= 1 while in hierarchical allreduce mode",
              inter_nranks));
      PADDLE_ENFORCE_EQ(
          trainers.size() % inter_nranks, 0,
          platform::errors::PreconditionNotMet(
              "The number of trainers %llu mod inter_nranks %d is not equal 0",
              trainers.size(), inter_nranks));

      inter_trainer_id = trainer_id % inter_nranks;

      if (trainer_id % inter_nranks == 0) {
        exter_trainer_id = trainer_id / inter_nranks;
      }
    }

    std::ostringstream ss;
    for (size_t i = 0; i < trainers.size(); i++) {
      ss << trainers[i] << ",";
    }

    VLOG(1) << "trainer_id:" << trainer_id
            << ", use_hierarchical_allreduce:" << use_hierarchical_allreduce
            << ", nccl_comm_num:" << nccl_comm_num
            << ", inter_nranks:" << inter_nranks
            << ", inter_trainer_id:" << inter_trainer_id
            << ", exter_trainer_id:" << exter_trainer_id
            << ", trainers:" << ss.str();

    int server_fd = -1;
    std::vector<ncclUniqueId> nccl_ids;
    nccl_ids.resize(nccl_comm_num);

    /// 1. init flat
    std::function<std::string(size_t)> func = platform::GetFlatNCCLVarName;
    // broadcast unique id
    if (trainer_id == 0) {
      GenNCCLID(&nccl_ids);

      // server endpoints
      std::vector<std::string> flat_endpoints;
      flat_endpoints.insert(flat_endpoints.begin(), trainers.begin() + 1,
                            trainers.end());
      platform::SendBroadCastCommID(flat_endpoints, &nccl_ids);
    } else {
      server_fd = platform::CreateListenSocket(endpoint);
      platform::RecvBroadCastCommID(server_fd, endpoint, &nccl_ids);
    }
    CopyNCCLIDToVar(nccl_ids, func, scope);

    /// 2. hierarchical inter ncclid
    func = platform::GetHierarchicalInterNCCLVarName;
    if (inter_trainer_id == 0) {
      std::ostringstream ss;
      ss << endpoint;
      std::vector<std::string> inter_endpoints;
      for (int i = trainer_id + 1; i < trainer_id + inter_nranks &&
                                   i < static_cast<int>(trainers.size());
           i++) {
        ss << ",";
        inter_endpoints.push_back(trainers[i]);
        ss << trainers[i];
      }
      VLOG(1) << "Hierarchical inter ring endpoints:" << ss.str();

      GenNCCLID(&nccl_ids);
      platform::SendBroadCastCommID(inter_endpoints, &nccl_ids);
      CopyNCCLIDToVar(nccl_ids, func, scope);
    } else if (inter_trainer_id > 0) {
      VLOG(1) << "Hierarchical inter ring";
      platform::RecvBroadCastCommID(server_fd, endpoint, &nccl_ids);
      CopyNCCLIDToVar(nccl_ids, func, scope);
    }

    /// 3. hierarchical exter ncclid
    func = platform::GetHierarchicalExterNCCLVarName;
    if (exter_trainer_id == 0) {
      std::ostringstream ss;
      std::vector<std::string> exter_endpoints;
      ss << endpoint;
      for (size_t i = inter_nranks; i < trainers.size(); i += inter_nranks) {
        ss << ",";
        exter_endpoints.push_back(trainers[i]);
        ss << trainers[i];
      }
      VLOG(1) << "Hierarchical exter ring endpoints:" << ss.str();

      GenNCCLID(&nccl_ids);
      platform::SendBroadCastCommID(exter_endpoints, &nccl_ids);
      CopyNCCLIDToVar(nccl_ids, func, scope);
    } else if (exter_trainer_id > 0) {
      VLOG(1) << "Hierarchical exter ring";
      platform::RecvBroadCastCommID(server_fd, endpoint, &nccl_ids);
      CopyNCCLIDToVar(nccl_ids, func, scope);
    }

    // close socket server
    if (trainer_id != 0) {
      platform::CloseSocket(server_fd);
    }
  }
};

class GenNCCLIdOpMaker : public framework::OpProtoAndCheckerMaker {
 public:
  void Make() override {
    AddOutput("NCCLID", "Raw variable contains a NCCL UniqueId instaces.");
    AddComment(R"DOC(
GenNCCLId operator

For trainer 0: generate a new UniqueId and send it to all the other trainers.
For trainer 1~n: start a gRPC server to get the UniqueId, once got, stop the server.
)DOC");
    AddAttr<std::vector<std::string>>(
        "trainers",
        "['trainer0_ip:port', 'trainer1_ip:port', ...] "
        "list of all trainer endpoints")
        .SetDefault({});
    AddAttr<int>("trainer_id",
                 "(int) "
                 "The index of the trainer in distributed training.");
    AddAttr<int>("nccl_comm_num",
                 "(int default 1) "
                 "The number of nccl communicator num.")
        .SetDefault(1);
    AddAttr<bool>("use_hierarchical_allreduce",
                  "(bool default false) "
                  "Wheter to use hierarchical allreduce.")
        .SetDefault(false);
    AddAttr<int>("hierarchical_allreduce_inter_nranks",
                 "(int default 1) "
                 "Wheter to use hierarchical allreduce.")
        .SetDefault(-1);
  }
};

}  // namespace operators
}  // namespace paddle

namespace ops = paddle::operators;

REGISTER_OPERATOR(gen_nccl_id, ops::GenNCCLIdOp, ops::GenNCCLIdOpMaker);