build_log.h

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// 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_BUILD_LOG_H_
#define NINJA_BUILD_LOG_H_

#include <map>
#include <string>
using namespace std;

#include "hash_map.h"

struct BuildConfig;
struct Edge;

/// Store a log of every command ran for every build.
/// It has a few uses:
///
/// 1) historical command lines for output files, so we know
///    when we need to rebuild due to the command changing
/// 2) historical timing information
/// 3) maybe we can generate some sort of build overview output
///    from it
struct BuildLog {
  BuildLog();
  ~BuildLog() { Close(); }

  void SetConfig(BuildConfig* config) { config_ = config; }
  bool OpenForWrite(const string& path, string* err);
  void RecordCommand(Edge* edge, int start_time, int end_time,
                     time_t restat_mtime = 0);
  void Close();

  /// Load the on-disk log.
  bool Load(const string& path, string* err);

  struct LogEntry {
    string output;
    string command;
    int start_time;
    int end_time;
    time_t restat_mtime;

    // Used by tests.
    bool operator==(const LogEntry& o) {
      return output == o.output && command == o.command &&
          start_time == o.start_time && end_time == o.end_time &&
          restat_mtime == o.restat_mtime;
    }
  };

  /// Lookup a previously-run command by its output path.
  LogEntry* LookupByOutput(const string& path);

  /// Serialize an entry into a log file.
  void WriteEntry(FILE* f, const LogEntry& entry);

  /// Rewrite the known log entries, throwing away old data.
  bool Recompact(const string& path, string* err);

  typedef ExternalStringHashMap<LogEntry*>::Type Log;
  Log log_;
  FILE* log_file_;
  BuildConfig* config_;
  bool needs_recompaction_;
};

#endif // NINJA_BUILD_LOG_H_