/* Copyright 2017 The TensorFlow 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 "tensorflow/core/grappler/grappler_item.h"

#include <unordered_map>
#include <unordered_set>
#include <vector>

#include "absl/container/flat_hash_set.h"
#include "absl/strings/str_join.h"
#include "tensorflow/core/framework/attr_value.pb.h"
#include "tensorflow/core/framework/node_def.pb.h"
#include "tensorflow/core/grappler/op_types.h"
#include "tensorflow/core/grappler/utils.h"
#include "tensorflow/core/util/device_name_utils.h"

namespace tensorflow {
namespace grappler {

GrapplerItem GrapplerItem::WithGraph(GraphDef&& graph_def) const {
  GrapplerItem item;
  item.id = id;
  item.feed = feed;
  item.fetch = fetch;
  item.init_ops = init_ops;
  item.keep_ops = keep_ops;
  item.expected_init_time = expected_init_time;
  item.save_op = save_op;
  item.restore_op = restore_op;
  item.save_restore_loc_tensor = save_restore_loc_tensor;
  item.queue_runners = queue_runners;
  item.devices_ = devices_;
  item.optimization_options_ = optimization_options_;
  item.graph.Swap(&graph_def);
  return item;
}

std::vector<const NodeDef*> GrapplerItem::MainOpsFanin() const {
  return ComputeTransitiveFanin(graph, fetch);
}

std::vector<const NodeDef*> GrapplerItem::EnqueueOpsFanin() const {
  std::vector<string> enqueue_ops;
  for (const auto& queue_runner : queue_runners) {
    for (const string& enqueue_op : queue_runner.enqueue_op_name()) {
      enqueue_ops.push_back(enqueue_op);
    }
  }
  return ComputeTransitiveFanin(graph, enqueue_ops);
}

std::vector<const NodeDef*> GrapplerItem::InitOpsFanin() const {
  return ComputeTransitiveFanin(graph, init_ops);
}

std::vector<const NodeDef*> GrapplerItem::MainVariables() const {
  std::vector<const NodeDef*> fanin = ComputeTransitiveFanin(graph, init_ops);
  std::vector<const NodeDef*> vars;
  for (const NodeDef* node : fanin) {
    if (IsVariable(*node)) {
      vars.push_back(node);
    }
  }
  return vars;
}

std::unordered_set<string> GrapplerItem::NodesToPreserve() const {
  std::unordered_set<string> result;
  for (const string& f : fetch) {
    VLOG(1) << "Add fetch " << f;
    result.insert(NodeName(f));
  }
  for (const auto& f : feed) {
    VLOG(1) << "Add feed " << f.first;
    result.insert(NodeName(f.first));
  }
  for (const auto& node : init_ops) {
    result.insert(NodeName(node));
  }
  for (const auto& node : keep_ops) {
    result.insert(NodeName(node));
  }
  if (!save_op.empty()) {
    result.insert(NodeName(save_op));
  }
  if (!restore_op.empty()) {
    result.insert(NodeName(restore_op));
  }
  if (!save_restore_loc_tensor.empty()) {
    result.insert(NodeName(save_restore_loc_tensor));
  }

  for (const auto& queue_runner : queue_runners) {
    for (const string& enqueue_op : queue_runner.enqueue_op_name()) {
      result.insert(NodeName(enqueue_op));
    }
    if (!queue_runner.close_op_name().empty()) {
      result.insert(NodeName(queue_runner.close_op_name()));
    }
    if (!queue_runner.cancel_op_name().empty()) {
      result.insert(NodeName(queue_runner.cancel_op_name()));
    }
  }

  absl::optional<FunctionLibraryDefinition> fn_library;
  if (!optimization_options_.allow_pruning_stateful_and_dataset_ops) {
    fn_library.emplace(OpRegistry::Global(), graph.library());
  }
  for (const NodeDef& node : graph.node()) {
    const auto attrs = AttrSlice(&node.attr());

    // Tensorflow functions do not prune stateful or dataset-output ops from
    // the function body (see PruneFunctionBody in common_runtime/function.cc).
    if (!optimization_options_.allow_pruning_stateful_and_dataset_ops &&
        (IsStateful(node, &*fn_library) || IsDataset(node))) {
      result.insert(node.name());
    }

    // Do not remove ops with attribute _grappler_do_not_remove. This is useful
    // for debugging.
    bool do_not_remove;
    if (TryGetNodeAttr(attrs, "_grappler_do_not_remove", &do_not_remove) &&
        do_not_remove) {
      result.insert(node.name());
    }
  }

  return result;
}

const std::unordered_set<string>& GrapplerItem::devices() const {
  return devices_;
}

Status GrapplerItem::AddDevice(const string& device) {
  DeviceNameUtils::ParsedName name;

  if (!DeviceNameUtils::ParseFullName(device, &name)) {
    return errors::InvalidArgument("Invalid device name: device=", device);

  } else if (!name.has_job || !name.has_replica || !name.has_task ||
             !name.has_type || !name.has_id) {
    return errors::InvalidArgument("Not a fully defined device name: device=",
                                   device);
  }

  devices_.insert(DeviceNameUtils::ParsedNameToString(name));
  return Status::OK();
}

Status GrapplerItem::AddDevices(const GrapplerItem& other) {
  std::vector<absl::string_view> invalid_devices;
  for (const string& device : other.devices()) {
    Status added = AddDevice(device);
    if (!added.ok()) invalid_devices.emplace_back(device);
  }
  return invalid_devices.empty()
             ? Status::OK()
             : errors::InvalidArgument("Skipped invalid devices: [",
                                       absl::StrJoin(invalid_devices, ", "),
                                       "]");
}

Status GrapplerItem::InferDevicesFromGraph() {
  absl::flat_hash_set<absl::string_view> invalid_devices;
  for (const NodeDef& node : graph.node()) {
    Status added = AddDevice(node.device());
    if (!added.ok()) invalid_devices.insert(node.device());
  }
  VLOG(2) << "Inferred device set: [" << absl::StrJoin(devices_, ", ") << "]";
  return invalid_devices.empty()
             ? Status::OK()
             : errors::InvalidArgument("Skipped invalid devices: [",
                                       absl::StrJoin(invalid_devices, ", "),
                                       "]");
}

void GrapplerItem::ClearDevices() { devices_.clear(); }

const GrapplerItem::OptimizationOptions& GrapplerItem::optimization_options()
    const {
  return optimization_options_;
}

GrapplerItem::OptimizationOptions& GrapplerItem::optimization_options() {
  return optimization_options_;
}

std::vector<const NodeDef*> ComputeTransitiveFanin(
    const GraphDef& graph, const std::vector<string>& terminal_nodes) {
  bool ill_formed = false;
  std::vector<const NodeDef*> result =
      ComputeTransitiveFanin(graph, terminal_nodes, &ill_formed);
  CHECK(!ill_formed);
  return result;
}

std::vector<const NodeDef*> ComputeTransitiveFanin(
    const GraphDef& graph, const std::vector<string>& terminal_nodes,
    bool* ill_formed) {
  *ill_formed = false;
  std::unordered_map<string, const NodeDef*> name_to_node;
  std::unordered_map<string, const NodeDef*> name_to_send;
  for (const auto& node : graph.node()) {
    name_to_node[node.name()] = &node;
    if (node.op() == "_Send") {
      const auto& attr = node.attr();
      name_to_send[attr.at("tensor_name").s()] = &node;
    }
  }

  std::vector<const NodeDef*> queue;
  for (const string& root : terminal_nodes) {
    const NodeDef* node = name_to_node[NodeName(root)];
    if (!node) {
      *ill_formed = true;
      VLOG(2) << "ComputeTransitiveFanin: problem with root node: " << root;
      return {};
    }
    queue.push_back(node);
  }

  std::vector<const NodeDef*> result;
  std::unordered_set<const NodeDef*> visited;

  while (!queue.empty()) {
    const NodeDef* node = queue.back();
    queue.pop_back();
    if (!visited.insert(node).second) {
      // The node has already been visited.
      continue;
    }
    result.push_back(node);
    for (const string& input : node->input()) {
      const NodeDef* in = name_to_node[NodeName(input)];
      if (!in) {
        VLOG(2) << "ComputeTransitiveFanin: problem with node: " << input;
        *ill_formed = true;
        return {};
      }
      queue.push_back(in);
    }
    if (node->op() == "_Recv") {
      const auto& attr = node->attr();
      const NodeDef* send = name_to_send[attr.at("tensor_name").s()];
      if (send) {
        queue.push_back(send);
      }
      // Subgraph after partitioning may have either _Send or _Recv, not both.
      // So, we do not set ill_formed for missing _Send.
    }
  }
  return result;
}

}  // end namespace grappler
}  // end namespace tensorflow
