/* Copyright 2015 Google Inc. 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 "tensorflow/core/kernels/sendrecv_ops.h"

#include "tensorflow/core/framework/op.h"
#include "tensorflow/core/framework/op_kernel.h"
#include "tensorflow/core/lib/strings/numbers.h"
#include "tensorflow/core/lib/strings/strcat.h"
#include "tensorflow/core/platform/logging.h"

namespace tensorflow {

static string GetRendezvousKeyPrefix(const string& send_device,
                                     const string& recv_device,
                                     const uint64 send_device_incarnation,
                                     const string& tensor_name) {
  return strings::StrCat(send_device, ";",
                         strings::FpToString(send_device_incarnation), ";",
                         recv_device, ";", tensor_name);
}

static string GetRendezvousKey(const string& key_prefix,
                               const FrameAndIter& frame_iter) {
  return strings::StrCat(key_prefix, ";", frame_iter.frame_id, ":",
                         frame_iter.iter_id);
}

SendOp::SendOp(OpKernelConstruction* ctx) : OpKernel(ctx) {
  string send_device;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("send_device", &send_device));
  string recv_device;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("recv_device", &recv_device));
  uint64 send_device_incarnation;
  OP_REQUIRES_OK(
      ctx, ctx->GetAttr("send_device_incarnation",
                        reinterpret_cast<int64*>(&send_device_incarnation)));
  string tensor_name;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("tensor_name", &tensor_name));
  key_prefix_ = GetRendezvousKeyPrefix(send_device, recv_device,
                                       send_device_incarnation, tensor_name);
}

void SendOp::Compute(OpKernelContext* ctx) {
  OP_REQUIRES(
      ctx, ctx->rendezvous() != nullptr,
      errors::Internal("Op kernel context needs to provide a rendezvous."));
  const string key = GetRendezvousKey(key_prefix_, ctx->frame_iter());
  VLOG(2) << "Send " << key;

  // The device context may be passed between the Send/Recv
  // boundary, so that the device context used to produce the Tensor
  // is used when performing the copy on the recv side (which may be
  // a different device).
  Rendezvous::Args args;
  args.device_context = ctx->op_device_context();
  args.alloc_attrs = ctx->input_alloc_attr(0);
  Status s =
      ctx->rendezvous()->Send(key, args, ctx->input(0), ctx->is_input_dead());
  ctx->SetStatus(s);
}

REGISTER_KERNEL_BUILDER(Name("_Send").Device(DEVICE_CPU), SendOp);
REGISTER_KERNEL_BUILDER(Name("_Send").Device(DEVICE_GPU), SendOp);

REGISTER_KERNEL_BUILDER(Name("_HostSend").Device(DEVICE_CPU), SendOp);
REGISTER_KERNEL_BUILDER(
    Name("_HostSend").Device(DEVICE_GPU).HostMemory("tensor"), SendOp);

RecvOp::RecvOp(OpKernelConstruction* ctx) : AsyncOpKernel(ctx) {
  string send_device;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("send_device", &send_device));
  string recv_device;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("recv_device", &recv_device));
  uint64 send_device_incarnation;
  OP_REQUIRES_OK(
      ctx, ctx->GetAttr("send_device_incarnation",
                        reinterpret_cast<int64*>(&send_device_incarnation)));
  string tensor_name;
  OP_REQUIRES_OK(ctx, ctx->GetAttr("tensor_name", &tensor_name));
  key_prefix_ = GetRendezvousKeyPrefix(send_device, recv_device,
                                       send_device_incarnation, tensor_name);
}

void RecvOp::ComputeAsync(OpKernelContext* ctx, DoneCallback done) {
  OP_REQUIRES(
      ctx, ctx->rendezvous() != nullptr,
      errors::Internal("Op kernel context needs to provide a rendezvous."));
  const string key = GetRendezvousKey(key_prefix_, ctx->frame_iter());
  VLOG(2) << "Recv " << key;

  Rendezvous::Args args;
  args.device_context = ctx->op_device_context();
  args.alloc_attrs = ctx->output_alloc_attr(0);
  ctx->rendezvous()->RecvAsync(
      key, args, [ctx, done](const Status& s, const Rendezvous::Args& send_args,
                             const Rendezvous::Args& recv_args,
                             const Tensor& val, bool is_dead) {
        ctx->SetStatus(s);
        if (s.ok()) {
          // 'ctx' allocates the output tensor of the expected type.  The
          // runtime checks whether the tensor received here is the same type.
          if (!is_dead) {
            ctx->set_output(0, val);
          }
          *ctx->is_output_dead() = is_dead;
        }
        done();
      });
}

REGISTER_KERNEL_BUILDER(Name("_Recv").Device(DEVICE_CPU), RecvOp);
REGISTER_KERNEL_BUILDER(Name("_Recv").Device(DEVICE_GPU), RecvOp);

REGISTER_KERNEL_BUILDER(Name("_HostRecv").Device(DEVICE_CPU), RecvOp);
REGISTER_KERNEL_BUILDER(
    Name("_HostRecv").Device(DEVICE_GPU).HostMemory("tensor"), RecvOp);

}  // end namespace tensorflow
