src/state.h

// Copyright 2011 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.

#ifndef NINJA_STATE_H_
#define NINJA_STATE_H_

#include <map>
#include <memory>
#include <set>
#include <string>
#include <vector>

#include "eval_env.h"
#include "graph.h"
#include "hash_map.h"
#include "util.h"

struct Edge;
struct Node;
struct Rule;

/// A pool for delayed edges.
/// Pools are scoped to a State. Edges within a State will share Pools. A Pool
/// will keep a count of the total 'weight' of the currently scheduled edges. If
/// a Plan attempts to schedule an Edge which would cause the total weight to
/// exceed the depth of the Pool, the Pool will enqueue the Edge instead of
/// allowing the Plan to schedule it. The Pool will relinquish queued Edges when
/// the total scheduled weight diminishes enough (i.e. when a scheduled edge
/// completes).
struct Pool {
  Pool(const std::string& name, int depth)
      : name_(name), current_use_(0), depth_(depth),
        is_console_(name == "console"), delayed_() {}

  /// A depth of 0 is infinite
  bool is_valid() const { return depth_ >= 0; }

  /// Return true if this is the console pool.
  bool is_console() const { return is_console_; }

  int depth() const { return depth_; }
  const std::string& name() const { return name_; }
  int current_use() const { return current_use_; }

  /// true if the Pool might delay this edge
  bool ShouldDelayEdge() const { return depth_ != 0; }

  /// informs this Pool that the given edge is committed to be run.
  /// Pool will count this edge as using resources from this pool.
  void EdgeScheduled(const Edge& edge);

  /// informs this Pool that the given edge is no longer runnable, and should
  /// relinquish its resources back to the pool
  void EdgeFinished(const Edge& edge);

  /// adds the given edge to this Pool to be delayed.
  void DelayEdge(Edge* edge);

  /// Pool will add zero or more edges to the ready_queue
  void RetrieveReadyEdges(EdgeSet* ready_queue);

  /// Dump the Pool and its edges (useful for debugging).
  void Dump() const;

  /// Reset state.
  void Reset();

 private:
  std::string name_;

  /// |current_use_| is the total of the weights of the edges which are
  /// currently scheduled in the Plan (i.e. the edges in Plan::ready_).
  int current_use_;
  int depth_;
  bool is_console_;

  struct WeightedEdgeCmp {
    bool operator()(const Edge* a, const Edge* b) const {
      if (!a) return b;
      if (!b) return false;
      int weight_diff = a->weight() - b->weight();
      return ((weight_diff < 0) || (weight_diff == 0 && EdgeCmp()(a, b)));
    }
  };

  typedef std::set<Edge*, WeightedEdgeCmp> DelayedEdges;
  DelayedEdges delayed_;
};

/// Global state (file status) for a single run.
struct State {
  State();

  ~State();

  State(State&&) noexcept = default;
  State& operator=(State&&) noexcept = default;

  State(const State&) = delete;
  State& operator=(const State&) = delete;

  /// Add pool instance, takes ownership.
  void AddPool(Pool* pool);

  Pool* LookupPool(const std::string& pool_name);

  /// Return pointer to the default pool. This one is always created implicitly.
  Pool* default_pool() const;

  /// Return pointer to the console_pool(). This one is always created
  /// implicitly.
  Pool* console_pool() const;

  /// Return pointer to phony rule. This one is always created implicitly.
  const Rule* phony_rule() const { return phony_rule_; }

  /// Allocate new Rule instance.
  Rule* NewRule(StringPiece name);

  Edge* AddEdge(const Rule* rule);

  Node* GetNode(StringPiece path, uint64_t slash_bits);
  Node* LookupNode(StringPiece path) const;
  Node* SpellcheckNode(const std::string& path);

  /// Add input / output / validation nodes to a given edge. This also
  /// ensure that the generated_by_dep_loader() flag for all these nodes
  /// is set to false, to indicate that they come from the input manifest.
  void AddIn(Edge* edge, StringPiece path, uint64_t slash_bits);
  bool AddOut(Edge* edge, StringPiece path, uint64_t slash_bits);
  void AddValidation(Edge* edge, StringPiece path, uint64_t slash_bits);
  bool AddDefault(StringPiece path, std::string* error);

  /// Reset state.  Keeps all nodes and edges, but restores them to the
  /// state where we haven't yet examined the disk for dirty state.
  void Reset();

  /// Dump the nodes and Pools (useful for debugging).
  void Dump();

  /// @return the root node(s) of the graph. (Root nodes have no output edges).
  /// @param error where to write the error message if somethings went wrong.
  std::vector<Node*> RootNodes(std::string* error) const;
  std::vector<Node*> DefaultNodes(std::string* error) const;

  /// Create new BindingEnv instance.
  BindingEnv* CreateNewEnv(BindingEnv* parent);

  /// Return top-level BindingEnv instance.
  BindingEnv& bindings() const { return *bindings_[0]; }

  /// Mapping of path -> Node.
  /// NOTE: This owns all Node instances, but a DepsLog instance contains
  /// pointers to them as well.
  typedef ExternalStringHashMap<Node*>::Type Paths;
  Paths paths_;

  /// All the pools used in the graph.
  std::map<std::string, std::unique_ptr<Pool>> pools_;

  /// The default and console pools. These points to elements of pools_.
  Pool* default_pool_ = nullptr;
  Pool* console_pool_ = nullptr;

  /// All the edges of the graph.
  /// NOTE: This owns all Edge instances.
  std::vector<Edge*> edges_;

  Rule* phony_rule_ = nullptr;

  /// Note: BindingEnv need pointer stability (as they all include a parent
  /// pointer)
  std::vector<std::unique_ptr<BindingEnv>> bindings_;

  /// Points to elements of paths_.
  std::vector<Node*> defaults_;
};

#endif  // NINJA_STATE_H_