// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.

//  This source code is licensed under both the GPLv2 (found in the

//  COPYING file in the root directory) and Apache 2.0 License

//  (found in the LICENSE.Apache file in the root directory).

#pragma once

#include <stdint.h>

#include <string>

#include "rocksdb/perf_level.h"

/*

 * NOTE:

 * If you plan to add new metrics, please read documentation in perf_level.h and

 * try to come up with a metric name that follows the naming conventions

 * mentioned there. It helps to indicate the metric's starting enabling P

 * erfLevel. Document this starting PerfLevel if the metric name cannot meet the

 * naming conventions.

 */

// A thread local context for gathering io-stats efficiently and transparently.

// Use SetPerfLevel(PerfLevel::kEnableTime) to enable time stats.

//

namespace ROCKSDB_NAMESPACE {

// EXPERIMENTAL: the IO statistics for tiered storage. It matches with each

// item in Temperature class.

struct FileIOByTemperature {

  // the number of bytes read to Temperature::kHot file

  uint64_t hot_file_bytes_read;

  // the number of bytes read to Temperature::kWarm file

  uint64_t warm_file_bytes_read;

  // the number of bytes read to Temperature::kCool file

  uint64_t cool_file_bytes_read;

  // the number of bytes read to Temperature::kCold file

  uint64_t cold_file_bytes_read;

  // the number of bytes read to Temperature::kIce file

  uint64_t ice_file_bytes_read;

  // the number of bytes read to Temperature::kUnknown file not in last level

  uint64_t unknown_non_last_level_bytes_read;

  // the number of bytes read to Temperature::kUnknown file in last level

  uint64_t unknown_last_level_bytes_read;

  // total number of reads to Temperature::kHot file

  uint64_t hot_file_read_count;

  // total number of reads to Temperature::kWarm file

  uint64_t warm_file_read_count;

  // total number of reads to Temperature::kCool file

  uint64_t cool_file_read_count;

  // total number of reads to Temperature::kCold file

  uint64_t cold_file_read_count;

  // total number of reads to Temperature::kIce file

  uint64_t ice_file_read_count;

  // total number of reads to Temperature::kUnknown file not in last level

  uint64_t unknown_non_last_level_read_count;

  // total number of reads to Temperature::kUnknown file in last level

  uint64_t unknown_last_level_read_count;

  // reset all the statistics to 0.

  void Reset() {

    hot_file_bytes_read = 0;

    warm_file_bytes_read = 0;

    cool_file_bytes_read = 0;

    cold_file_bytes_read = 0;

    ice_file_bytes_read = 0;

    unknown_non_last_level_bytes_read = 0;

    unknown_last_level_bytes_read = 0;

    hot_file_read_count = 0;

    warm_file_read_count = 0;

    cool_file_read_count = 0;

    cold_file_read_count = 0;

    ice_file_read_count = 0;

    unknown_non_last_level_read_count = 0;

    unknown_last_level_read_count = 0;

  }

};

struct IOStatsContext {

  // reset all io-stats counter to zero

  void Reset();

  std::string ToString(bool exclude_zero_counters = false) const;

  // the thread pool id

  uint64_t thread_pool_id;

  // number of bytes that has been written.

  uint64_t bytes_written;

  // number of bytes that has been read.

  uint64_t bytes_read;

  // time spent in open() and fopen().

  uint64_t open_nanos;

  // time spent in fallocate().

  uint64_t allocate_nanos;

  // time spent in write() and pwrite().

  uint64_t write_nanos;

  // time spent in read() and pread()

  uint64_t read_nanos;

  // time spent in sync_file_range().

  uint64_t range_sync_nanos;

  // time spent in fsync

  uint64_t fsync_nanos;

  // time spent in preparing write (fallocate etc).

  uint64_t prepare_write_nanos;

  // time spent in Logger::Logv().

  uint64_t logger_nanos;

  // CPU time spent in write() and pwrite()

  uint64_t cpu_write_nanos;

  // CPU time spent in read() and pread()

  uint64_t cpu_read_nanos;

  FileIOByTemperature file_io_stats_by_temperature;

  // It is not consistent that whether iostats follows PerfLevel.Timer counters

  // follows it but BackupEngine relies on counter metrics to always be there.

  // Here we create a backdoor option to disable some counters, so that some

  // existing stats are not polluted by file operations, such as logging, by

  // turning this off.

  bool disable_iostats = false;

};

// If RocksDB is compiled with -DNIOSTATS_CONTEXT, then a pointer to a global,

// non-thread-local IOStatsContext object will be returned. Attempts to update

// this object will be ignored, and reading from it will also be no-op.

// Otherwise, a pointer to a thread-local IOStatsContext object will be

// returned.

//

// This function never returns nullptr.

IOStatsContext* get_iostats_context();

}  // namespace ROCKSDB_NAMESPACE