rocksdb/util/auto_roll_logger.h

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Logger implementation that can be shared by all environments
// where enough posix functionality is available.

#ifndef STORAGE_LEVELDB_UTIL_AUTO_ROLL_LOGGER_H
#define STORAGE_LEVELDB_UTIL_AUTO_ROLL_LOGGER_H

#include "util/posix_logger.h"
#include "db/filename.h"

namespace leveldb {

// Rolls the log file by size and/or time
class AutoRollLogger : public Logger {
 public:
  AutoRollLogger(Env* env, const std::string& dbname,
                 const std::string& db_log_dir,
                 size_t log_max_size,
                 size_t log_file_time_to_roll):
     dbname_(dbname),
     db_log_dir_(db_log_dir),
     env_(env),
     status_(Status::OK()),
     kMaxLogFileSize(log_max_size),
     kLogFileTimeToRoll(log_file_time_to_roll),
     cached_now(static_cast<uint64_t>(env_->NowMicros() * 1e-6)),
     ctime_(cached_now),
     cached_now_access_count(0),
     call_NowMicros_every_N_records_(100) {
    env->GetAbsolutePath(dbname, &db_absolute_path_);
    log_fname_ = InfoLogFileName(dbname_, db_absolute_path_, db_log_dir_);
    RollLogFile();
    ResetLogger();
  }

  void Logv(const char* format, va_list ap);

  // check if the logger has encountered any problem.
  Status GetStatus() {
    return status_;
  }

  size_t GetLogFileSize() const {
    return logger_->GetLogFileSize();
  }

  virtual ~AutoRollLogger() {
  }

  void SetCallNowMicrosEveryNRecords(uint64_t call_NowMicros_every_N_records) {
    call_NowMicros_every_N_records_ = call_NowMicros_every_N_records;
  }

 private:

  bool LogExpired();
  Status ResetLogger();
  void RollLogFile();

  std::string log_fname_; // Current active info log's file name.
  std::string dbname_;
  std::string db_log_dir_;
  std::string db_absolute_path_;
  Env* env_;
  std::shared_ptr<Logger> logger_;
  // current status of the logger
  Status status_;
  const size_t kMaxLogFileSize;
  const size_t kLogFileTimeToRoll;
  // to avoid frequent env->NowMicros() calls, we cached the current time
  uint64_t cached_now;
  uint64_t ctime_;
  uint64_t cached_now_access_count;
  uint64_t call_NowMicros_every_N_records_;
};

// Facade to craete logger automatically
Status CreateLoggerFromOptions(
    const std::string& dbname,
    const std::string& db_log_dir,
    Env* env,
    const Options& options,
    std::shared_ptr<Logger>* logger);

}  // namespace leveldb

#endif  // STORAGE_LEVELDB_UTIL_AUTO_ROLL_LOGGER_H