path: root/tensorflow/core/graph/graph.cc

#include "tensorflow/core/graph/graph.h"

#include "tensorflow/core/framework/node_def_util.h"
#include "tensorflow/core/framework/op_kernel.h"
#include "tensorflow/core/lib/core/errors.h"
#include "tensorflow/core/lib/gtl/map_util.h"
#include "tensorflow/core/lib/strings/strcat.h"
#include "tensorflow/core/platform/logging.h"

namespace tensorflow {

// Node

string Node::DebugString() const {
  if (this == nullptr) {
    return "{nullptr}";
  }
  string ret = strings::StrCat("{name:'", name(), "' id:", id_);
  if (IsSource()) {
    strings::StrAppend(&ret, " source}");
  } else if (IsSink()) {
    strings::StrAppend(&ret, " sink}");
  } else {
    strings::StrAppend(&ret, " op device:");
    strings::StrAppend(&ret, "{", assigned_device_name_, "}");
    strings::StrAppend(&ret, " def:{", SummarizeNodeDef(def()), "}}");
  }
  return ret;
}

Node::Node()
    : id_(-1), cost_id_(-1), props_(nullptr), assigned_device_name_() {}

Node::~Node() {
  if (props_) {
    props_->Unref();
  }
}

void Node::Initialize(int id, int cost_id, Properties* props) {
  DCHECK_EQ(id_, -1);
  DCHECK(in_edges_.empty());
  DCHECK(out_edges_.empty());
  id_ = id;
  cost_id_ = cost_id;

  // Unref the old, assign the new properties.
  if (props_) {
    props_->Unref();
  }
  props_ = props;
}

void Node::Clear() {
  in_edges_.clear();
  out_edges_.clear();
  id_ = -1;
  cost_id_ = -1;

  if (props_) {
    props_->Unref();
    props_ = nullptr;
  }

  assigned_device_name_.clear();
}

gtl::iterator_range<NeighborIter> Node::out_nodes() const {
  return gtl::make_range(NeighborIter(out_edges_.begin(), false),
                         NeighborIter(out_edges_.end(), false));
}

gtl::iterator_range<NeighborIter> Node::in_nodes() const {
  return gtl::make_range(NeighborIter(in_edges_.begin(), true),
                         NeighborIter(in_edges_.end(), true));
}

// Node::Properties

Node::Properties::Properties(const OpDef* op_def, const NodeDef& node_def,
                             const DataTypeSlice inputs,
                             const DataTypeSlice outputs)
    : op_def_(op_def),
      node_def_(node_def),
      input_types_(inputs.begin(), inputs.end()),
      output_types_(outputs.begin(), outputs.end()) {}

Node::Properties::~Properties() {}

// Graph

Graph::Graph(const OpRegistryInterface* ops)
    : ops_(ops), arena_(8 << 10 /* 8kB */) {
  // Source and sink have no endpoints, just control edges.
  NodeDef def;
  def.set_name("_SOURCE");
  def.set_op("NoOp");
  Status status;
  Node* source = AddNode(def, &status);
  TF_CHECK_OK(status);
  CHECK_EQ(source->id(), kSourceId);

  def.set_name("_SINK");
  Node* sink = AddNode(def, &status);
  TF_CHECK_OK(status);
  CHECK_EQ(sink->id(), kSinkId);

  AddControlEdge(source, sink);
}

Graph::~Graph() {
  // Manually call the destructors for all the Nodes we constructed using
  // placement new.
  for (Node* node : nodes_) {
    if (node != nullptr) {
      node->~Node();
    }
  }
  for (Node* node : free_nodes_) {
    node->~Node();
  }
  // Edges have no destructor, and we arena-allocated them, so no need to
  // destroy them.
}

Node* Graph::AddNode(const NodeDef& node_def, Status* status) {
  const OpDef* op_def = ops_->LookUp(node_def.op(), status);
  if (op_def == nullptr) return nullptr;

  // TODO(vrv,josh11b): Find a location higher in the stack to add these defaults
  // to the NodeDef.
  NodeDef node_def_with_defaults(node_def);
  AddDefaultsToNodeDef(*op_def, &node_def_with_defaults);

  DataTypeVector inputs;
  DataTypeVector outputs;
  status->Update(
      InOutTypesForNode(node_def_with_defaults, *op_def, &inputs, &outputs));
  if (!status->ok()) {
    *status = AttachDef(*status, node_def_with_defaults);
    return nullptr;
  }

  Node* node = AllocateNode(
      new Node::Properties(op_def, node_def_with_defaults, inputs, outputs),
      nullptr);
  return node;
}

Node* Graph::CopyNode(Node* node) {
  DCHECK(!node->IsSource());
  DCHECK(!node->IsSink());
  Node::Properties* props = node->properties();
  props->Ref();
  Node* copy = AllocateNode(props, node);
  copy->set_assigned_device_name(node->assigned_device_name());
  return copy;
}

void Graph::RemoveNode(Node* node) {
  DCHECK(IsValidNode(node)) << node->DebugString();
  DCHECK(!node->IsSource());
  DCHECK(!node->IsSink());

  // Remove any edges involving this node.
  while (!node->in_edges_.empty()) {
    RemoveEdge(*node->in_edges_.begin());
  }
  while (!node->out_edges_.empty()) {
    RemoveEdge(*node->out_edges_.begin());
  }
  ReleaseNode(node);
}

const Edge* Graph::AddEdge(Node* source, int x, Node* dest, int y) {
  DCHECK(IsValidNode(source)) << source->DebugString();
  DCHECK(IsValidNode(dest)) << dest->DebugString();

  // source/sink must only be linked via control slots, and
  // control slots must only be linked to control slots.
  if (source == source_node() || dest == sink_node() || x == kControlSlot ||
      y == kControlSlot) {
    DCHECK_EQ(x, kControlSlot) << source->DebugString();
    DCHECK_EQ(y, kControlSlot) << dest->DebugString();
  }

  Edge* e = nullptr;
  if (free_edges_.empty()) {
    e = new (arena_.Alloc(sizeof(Edge))) Edge;  // placement new
  } else {
    e = free_edges_.back();
    free_edges_.pop_back();
  }
  e->id_ = edges_.size();
  e->src_ = source;
  e->dst_ = dest;
  e->src_output_ = x;
  e->dst_input_ = y;
  CHECK(source->out_edges_.insert(e).second);
  CHECK(dest->in_edges_.insert(e).second);
  edges_.push_back(e);
  edge_set_.insert(e);
  return e;
}

void Graph::RemoveEdge(const Edge* e) {
  DCHECK(IsValidNode(e->src_)) << e->src_->DebugString();
  DCHECK(IsValidNode(e->dst_)) << e->dst_->DebugString();
  CHECK_EQ(e->src_->out_edges_.erase(e), 1);
  CHECK_EQ(e->dst_->in_edges_.erase(e), 1);
  CHECK_EQ(e, edges_[e->id_]);

  CHECK_EQ(edge_set_.erase(e), 1);
  edges_[e->id_] = nullptr;

  Edge* del = const_cast<Edge*>(e);
  del->src_ = nullptr;
  del->dst_ = nullptr;
  del->id_ = -1;
  del->src_output_ = kControlSlot - 1;
  del->dst_input_ = kControlSlot - 1;
  free_edges_.push_back(del);
}

namespace {

void AddInput(NodeDef* dst, StringPiece src_name, int src_slot) {
  if (src_slot == Graph::kControlSlot) {
    dst->add_input(strings::StrCat("^", src_name));
  } else if (src_slot == 0) {
    dst->add_input(src_name.data(), src_name.size());
  } else {
    dst->add_input(strings::StrCat(src_name, ":", src_slot));
  }
}

}  // namespace

void Graph::ToGraphDef(GraphDef* graph_def) const {
  graph_def->Clear();
  std::vector<const Edge*>
      inputs;  // Construct this outside the loop for speed.
  for (const Node* node : nodes()) {
    if (!node->IsOp()) continue;
    NodeDef* node_def = graph_def->add_node();
    *node_def = node->def();

    // Use the node's assigned device, if any, instead of the device requested
    // in the NodeDef.
    if (!node->assigned_device_name().empty()) {
      node_def->set_device(node->assigned_device_name());
    }

    // Get the inputs for this Node.  We make sure control inputs are
    // after data inputs, as required by GraphDef.
    inputs.clear();
    inputs.resize(node->num_inputs(), nullptr);
    for (const Edge* edge : node->in_edges()) {
      if (edge->IsControlEdge()) {
        inputs.push_back(edge);
      } else {
        DCHECK(inputs[edge->dst_input()] == nullptr);
        inputs[edge->dst_input()] = edge;
      }
    }
    node_def->clear_input();
    for (size_t i = 0; i < inputs.size(); ++i) {
      const Edge* edge = inputs[i];
      if (edge == nullptr) {
        node_def->add_input(node->def().input(i));
      } else {
        const Node* src = edge->src();
        if (!src->IsOp()) continue;
        AddInput(node_def, src->name(), edge->src_output());
      }
    }
  }
}

string Graph::NewName(StringPiece prefix) {
  return strings::StrCat(prefix, "/_", name_counter_++);
}

gtl::iterator_range<NodeIter> Graph::nodes() const {
  // Note that NodeId 0 is always valid since we don't let the source
  // node be removed from the graph.
  return gtl::make_range(NodeIter(this, 0), NodeIter(this, num_node_ids()));
}

bool Graph::IsValidNode(Node* node) const {
  if (node == nullptr) return false;
  const int id = node->id();
  if (id < 0 || static_cast<size_t>(id) >= nodes_.size()) return false;
  return nodes_[id] == node;
}

Node* Graph::AllocateNode(Node::Properties* props, const Node* cost_node) {
  Node* node = nullptr;
  if (free_nodes_.empty()) {
    node = new (arena_.Alloc(sizeof(Node))) Node;  // placement new
  } else {
    node = free_nodes_.back();
    free_nodes_.pop_back();
  }
  const int id = nodes_.size();
  int cost_id = cost_node ? cost_node->cost_id() : id;
  node->Initialize(id, cost_id, props);
  nodes_.push_back(node);
  return node;
}

void Graph::ReleaseNode(Node* node) {
  DCHECK(IsValidNode(node)) << node->DebugString();
  nodes_[node->id()] = nullptr;
  free_nodes_.push_back(node);
  node->Clear();
}

}  // namespace tensorflow