// 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 <stdio.h>

#include <memory>

#include <string>

#include "hash_map.h"

#include "load_status.h"

#include "timestamp.h"

#include "util.h"  // uint64_t

struct DiskInterface;

struct Edge;

/// Can answer questions about the manifest for the BuildLog.

struct BuildLogUser {

  /// Return if a given output is no longer part of the build manifest.

  /// This is only called during recompaction and doesn't have to be fast.

  virtual bool IsPathDead(StringPiece s) const = 0;

};

/// Store a log of every command ran for every build.

/// It has a few uses:

///

/// 1) (hashes of) command lines for existing output files, so we know

///    when we need to rebuild due to the command changing

/// 2) timing information, perhaps for generating reports

/// 3) restat information

struct BuildLog {

  BuildLog();

  ~BuildLog();

  /// Prepares writing to the log file without actually opening it - that will

  /// happen when/if it's needed

  bool OpenForWrite(const std::string& path, const BuildLogUser& user,

                    std::string* err);

  bool RecordCommand(Edge* edge, int start_time, int end_time,

                     TimeStamp mtime = 0);

  void Close();

  /// Load the on-disk log.

  LoadStatus Load(const std::string& path, std::string* err);

  struct LogEntry {

    std::string output;

    uint64_t command_hash = 0;

    int start_time = 0;

    int end_time = 0;

    TimeStamp mtime = 0;

    static uint64_t HashCommand(StringPiece command);

    // Used by tests.

    bool operator==(const LogEntry& o) const {

      return output == o.output && command_hash == o.command_hash &&

          start_time == o.start_time && end_time == o.end_time &&

          mtime == o.mtime;

    }

    explicit LogEntry(std::string output);

    LogEntry(const std::string& output, uint64_t command_hash,

             int start_time, int end_time, TimeStamp mtime);

  };

  /// Lookup a previously-run command by its output path.

  LogEntry* LookupByOutput(const std::string& path);

  /// Serialize an entry into a log file.

  bool WriteEntry(FILE* f, const LogEntry& entry);

  /// Rewrite the known log entries, throwing away old data.

  bool Recompact(const std::string& path, const BuildLogUser& user,

                 std::string* err);

  /// Restat all outputs in the log

  bool Restat(StringPiece path, const DiskInterface& disk_interface,

              int output_count, char** outputs, std::string* err);

  typedef ExternalStringHashMap<std::unique_ptr<LogEntry>>::Type Entries;

  const Entries& entries() const { return entries_; }

 private:

  /// Should be called before using log_file_. When false is returned, errno

  /// will be set.

  bool OpenForWriteIfNeeded();

  Entries entries_;

  FILE* log_file_ = nullptr;

  std::string log_file_path_;

  bool needs_recompaction_ = false;

};

#endif // NINJA_BUILD_LOG_H_