add topological sortting (#12059)

paddle/fluid/inference/analysis/data_flow_graph.cc

@@ -90,6 +90,20 @@ std::string DataFlowGraph::DotString() const {
   return dot.Build();
 }
 
+std::string DataFlowGraph::HumanReadableInfo(bool show_values,
+                                             bool show_functions) const {
+  std::stringstream values, functions;
+  for (auto &n : nodes.nodes()) {
+    if (show_values && n->IsValue()) {
+      values << n->repr() << "\n";
+    }
+    if (show_functions && n->IsFunction()) {
+      functions << n->repr() << "\n";
+    }
+  }
+  return "Values:\n" + values.str() + "\n\n" + "Functions:\n" + functions.str();
+}
+
 //
 // NodesBFSIterator
 //
@@ -146,7 +160,7 @@ bool GraphTraits<DataFlowGraph>::NodesBFSIterator::operator==(
   if ((!queue_.empty()) && (!other.queue_.empty())) {
     return queue_.front() == other.queue_.front() &&
            visited_.size() == other.visited_.size();  // here need to check the
-                                                      // equality of queue and
+    // equality of queue and
     // visited. Just a light but week implementation.
   }
   return false;
@@ -208,6 +222,76 @@ Node *GraphTraits<DataFlowGraph>::NodesDFSIterator::operator->() {
   return stack_.top();
 }
 
+GraphTraits<DataFlowGraph>::NodesTSIterator::NodesTSIterator(
+    const std::vector<Node *> &source) {
+  PADDLE_ENFORCE(!source.empty(),
+                 "Start points of topological sorting should not be empty!");
+  std::unordered_set<Node *> visited;
+  std::unordered_set<Node *> to_visit{source.begin(), source.end()};
+
+  std::vector<Node *> inlink_visited;
+  while (!to_visit.empty()) {
+    std::vector<Node *> queue(to_visit.begin(), to_visit.end());
+    for (auto *p : queue) {
+      inlink_visited.clear();
+
+      std::copy_if(p->inlinks.begin(), p->inlinks.end(),
+                   std::back_inserter(inlink_visited),
+                   [&](Node *x) { return visited.count(x); });
+
+      if (inlink_visited.size() == p->inlinks.size()) {
+        sorted_.push_back(p);
+        for (auto *_ : p->outlinks) {
+          if (!visited.count(_)) {
+            to_visit.insert(_);
+          }
+        }
+
+        to_visit.erase(p);
+        visited.insert(p);
+      }
+    }
+  }
+}
+
+GraphTraits<DataFlowGraph>::NodesTSIterator::NodesTSIterator(
+    const paddle::inference::analysis::GraphTraits<
+        DataFlowGraph>::NodesTSIterator &other)
+    : sorted_(other.sorted_), cursor_(other.cursor_) {}
+
+Node &GraphTraits<DataFlowGraph>::NodesTSIterator::operator*() {
+  PADDLE_ENFORCE_LT(cursor_, sorted_.size());
+  return *sorted_[cursor_];
+}
+
+paddle::inference::analysis::GraphTraits<DataFlowGraph>::NodesTSIterator
+    &GraphTraits<DataFlowGraph>::NodesTSIterator::operator++() {
+  if (++cursor_ >= sorted_.size()) {
+    sorted_.clear();
+    cursor_ = 0;
+  }
+  return *this;
+}
+paddle::inference::analysis::GraphTraits<DataFlowGraph>::NodesTSIterator &
+GraphTraits<DataFlowGraph>::NodesTSIterator::operator=(
+    const paddle::inference::analysis::GraphTraits<
+        DataFlowGraph>::NodesTSIterator &other) {
+  cursor_ = other.cursor_;
+  sorted_ = other.sorted_;
+  return *this;
+}
+
+bool GraphTraits<DataFlowGraph>::NodesTSIterator::operator==(
+    const paddle::inference::analysis::GraphTraits<
+        DataFlowGraph>::NodesTSIterator &other) {
+  return sorted_ == other.sorted_ && cursor_ == other.cursor_;
+}
+
+Node *GraphTraits<DataFlowGraph>::NodesTSIterator::operator->() {
+  PADDLE_ENFORCE_LT(cursor_, sorted_.size());
+  return sorted_[cursor_];
+}
+
 }  // namespace analysis
 }  // namespace inference
 }  // namespace paddle

paddle/fluid/inference/analysis/data_flow_graph.h

@@ -48,6 +48,9 @@ struct DataFlowGraph {
   // Output a DOT graph file for debug.
   std::string DotString() const;
 
+  std::string HumanReadableInfo(bool show_values = true,
+                                bool show_functions = true) const;
+
  private:
   // Remove duplicate edges and so on.
   void Clean();
@@ -107,6 +110,32 @@ struct GraphTraits<DataFlowGraph> {
     std::unordered_set<Node *> visited_;
   };
 
+  // Topological sorting iterator on nodes.
+  struct NodesTSIterator
+      : public std::iterator<std::forward_iterator_tag, Node *> {
+    NodesTSIterator() = default;
+    explicit NodesTSIterator(const std::vector<Node *> &source);
+    NodesTSIterator(NodesTSIterator &&other)
+        : sorted_(std::move(other.sorted_)), cursor_(other.cursor_) {
+      other.cursor_ = 0;
+    }
+    NodesTSIterator(const NodesTSIterator &other);
+
+    Node &operator*();
+    NodesTSIterator &operator++();
+    // TODO(Superjomn) current implementation just compare the first
+    // element, need to compare the graph and all the elements in the queue and
+    // set.
+    NodesTSIterator &operator=(const NodesTSIterator &other);
+    bool operator==(const NodesTSIterator &other);
+    bool operator!=(const NodesTSIterator &other) { return !(*this == other); }
+    Node *operator->();
+
+   private:
+    std::vector<Node *> sorted_;
+    int cursor_{0};
+  };
+
   explicit GraphTraits(DataFlowGraph *graph) : graph_(graph) {}
 
   // default use BFS to visit the nodes.
@@ -119,17 +148,24 @@ struct GraphTraits<DataFlowGraph> {
   iterator_range<NodesDFSIterator> nodes_in_DFS() {
     return iterator_range<NodesDFSIterator>(nodes_dfs_begin(), nodes_dfs_end());
   }
+  iterator_range<NodesTSIterator> nodes_in_TS() {
+    return iterator_range<NodesTSIterator>(nodes_ts_begin(), nodes_ts_end());
+  }
 
  private:
   NodesBFSIterator nodes_bfs_begin() {
     return NodesBFSIterator(graph_->inputs);
   }
   NodesBFSIterator nodes_bfs_end() { return NodesBFSIterator(); }
+
   NodesDFSIterator nodes_dfs_begin() {
     return NodesDFSIterator(graph_->inputs);
   }
   NodesDFSIterator nodes_dfs_end() { return NodesDFSIterator(); }
 
+  NodesTSIterator nodes_ts_begin() { return NodesTSIterator(graph_->inputs); }
+  NodesTSIterator nodes_ts_end() { return NodesTSIterator(); }
+
  private:
   DataFlowGraph *graph_;
 };

paddle/fluid/inference/analysis/data_flow_graph_tester.cc

@@ -24,11 +24,11 @@ TEST(DataFlowGraph, BFS) {
   auto dfg = ProgramDescToDFG(desc);
   dfg.Build();
 
-  for (auto* in : dfg.inputs) {
+  for (auto *in : dfg.inputs) {
     LOG(INFO) << "inputs: " << in->name() << " "
               << static_cast<int>(in->type());
   }
-  for (auto* out : dfg.outputs) {
+  for (auto *out : dfg.outputs) {
     LOG(INFO) << "outputs: " << out->name() << " "
               << static_cast<int>(out->type());
   }
@@ -57,6 +57,71 @@ TEST(DataFlowGraph, DFS) {
   ASSERT_EQ(count, dfg.nodes.size());
 }
 
+// Topological sorting.
+/*
+ * Graph topology
+ * inputs: 0, 1, 2
+ * 0 -> 4
+ * 0 -> 5
+ * 1 -> 6
+ * 2 -> 7
+ * 4 -> 5
+ * 4 -> 7
+ * 4 -> 3
+ * 7 -> 3
+ */
+TEST(DataFlowGraph, TS) {
+  DataFlowGraph graph;
+
+  for (int i = 0; i < 8; i++) {
+    auto *node = graph.nodes.Create(Node::Type::kValue);
+    node->SetName("node-" + std::to_string(i));
+  }
+
+  auto add_link = [&](int i, int j) {
+    Node *source = graph.nodes.GetMutable(i);
+    Node *target = graph.nodes.GetMutable(j);
+    target->inlinks.push_back(source);
+    source->outlinks.push_back(target);
+  };
+
+  graph.inputs.push_back(graph.nodes.GetMutable(0));
+  graph.inputs.push_back(graph.nodes.GetMutable(1));
+  graph.inputs.push_back(graph.nodes.GetMutable(2));
+
+  add_link(0, 4);
+  add_link(0, 5);
+  add_link(1, 6);
+  add_link(2, 7);
+  add_link(4, 5);
+  add_link(4, 7);
+  add_link(4, 3);
+  add_link(7, 3);
+
+  auto its = GraphTraits<DataFlowGraph>(&graph).nodes_in_TS();
+  std::vector<int> sorted_ids;
+  for (auto it = its.begin(); it != its.end(); ++it) {
+    LOG(INFO) << it->name();
+    sorted_ids.push_back(it->id());
+  }
+
+  // Assert a occurs prior to b in the sorted_ids.
+  auto assert_positive_sequence_pair = [&](int a, int b) {
+    auto a_offset = std::find(sorted_ids.begin(), sorted_ids.end(), a);
+    auto b_offset = std::find(sorted_ids.begin(), sorted_ids.end(), b);
+    ASSERT_LT(a_offset, b_offset);
+  };
+
+  assert_positive_sequence_pair(2, 7);
+  assert_positive_sequence_pair(7, 3);
+  assert_positive_sequence_pair(4, 3);
+  assert_positive_sequence_pair(0, 4);
+  assert_positive_sequence_pair(0, 5);
+  assert_positive_sequence_pair(1, 6);
+  assert_positive_sequence_pair(4, 5);
+  assert_positive_sequence_pair(4, 7);
+}
+
 }  // namespace analysis
 }  // namespace inference
 }  // namespace paddle