//
// Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS.  All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
//

#ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_METRICS_H_
#define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_METRICS_H_

#include <string>

#include "webrtc/base/atomicops.h"
#include "webrtc/base/checks.h"
#include "webrtc/common_types.h"

// Macros for allowing WebRTC clients (e.g. Chrome) to gather and aggregate
// statistics.
//
// Histogram for counters.
// RTC_HISTOGRAM_COUNTS(name, sample, min, max, bucket_count);
//
// Histogram for enumerators.
// The boundary should be above the max enumerator sample.
// RTC_HISTOGRAM_ENUMERATION(name, sample, boundary);
//
//
// The macros use the methods HistogramFactoryGetCounts,
// HistogramFactoryGetEnumeration and HistogramAdd.
//
// Therefore, WebRTC clients must either:
//
// - provide implementations of
//   Histogram* webrtc::metrics::HistogramFactoryGetCounts(
//       const std::string& name, int sample, int min, int max,
//       int bucket_count);
//   Histogram* webrtc::metrics::HistogramFactoryGetEnumeration(
//       const std::string& name, int sample, int boundary);
//   void webrtc::metrics::HistogramAdd(
//       Histogram* histogram_pointer, const std::string& name, int sample);
//
// - or link with the default implementations (i.e.
//   system_wrappers/system_wrappers.gyp:metrics_default).
//
//
// Example usage:
//
// RTC_HISTOGRAM_COUNTS("WebRTC.Video.NacksSent", nacks_sent, 1, 100000, 100);
//
// enum Types {
//   kTypeX,
//   kTypeY,
//   kBoundary,
// };
//
// RTC_HISTOGRAM_ENUMERATION("WebRTC.Types", kTypeX, kBoundary);


// Macros for adding samples to a named histogram.

// Histogram for counters (exponentially spaced buckets).
#define RTC_HISTOGRAM_COUNTS_100(name, sample) \
  RTC_HISTOGRAM_COUNTS(name, sample, 1, 100, 50)

#define RTC_HISTOGRAM_COUNTS_200(name, sample) \
  RTC_HISTOGRAM_COUNTS(name, sample, 1, 200, 50)

#define RTC_HISTOGRAM_COUNTS_1000(name, sample) \
  RTC_HISTOGRAM_COUNTS(name, sample, 1, 1000, 50)

#define RTC_HISTOGRAM_COUNTS_10000(name, sample) \
  RTC_HISTOGRAM_COUNTS(name, sample, 1, 10000, 50)

#define RTC_HISTOGRAM_COUNTS_100000(name, sample) \
  RTC_HISTOGRAM_COUNTS(name, sample, 1, 100000, 50)

#define RTC_HISTOGRAM_COUNTS(name, sample, min, max, bucket_count) \
  RTC_HISTOGRAM_COMMON_BLOCK(name, sample, \
      webrtc::metrics::HistogramFactoryGetCounts(name, min, max, bucket_count))

// Deprecated.
// TODO(asapersson): Remove.
#define RTC_HISTOGRAM_COUNTS_SPARSE_100(name, sample) \
  RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, 1, 100, 50)

#define RTC_HISTOGRAM_COUNTS_SPARSE_200(name, sample) \
  RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, 1, 200, 50)

#define RTC_HISTOGRAM_COUNTS_SPARSE_1000(name, sample) \
  RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, 1, 1000, 50)

#define RTC_HISTOGRAM_COUNTS_SPARSE_10000(name, sample) \
  RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, 1, 10000, 50)

#define RTC_HISTOGRAM_COUNTS_SPARSE_100000(name, sample) \
  RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, 1, 100000, 50)

#define RTC_HISTOGRAM_COUNTS_SPARSE(name, sample, min, max, bucket_count) \
  RTC_HISTOGRAM_COMMON_BLOCK_SLOW(name, sample, \
      webrtc::metrics::HistogramFactoryGetCounts(name, min, max, bucket_count))

// Histogram for percentage (evenly spaced buckets).
#define RTC_HISTOGRAM_PERCENTAGE(name, sample) \
  RTC_HISTOGRAM_ENUMERATION(name, sample, 101)

// Deprecated.
// TODO(asapersson): Remove.
#define RTC_HISTOGRAM_PERCENTAGE_SPARSE(name, sample) \
  RTC_HISTOGRAM_ENUMERATION_SPARSE(name, sample, 101)

// Histogram for enumerators (evenly spaced buckets).
// |boundary| should be above the max enumerator sample.
#define RTC_HISTOGRAM_ENUMERATION(name, sample, boundary) \
  RTC_HISTOGRAM_COMMON_BLOCK(name, sample, \
      webrtc::metrics::HistogramFactoryGetEnumeration(name, boundary))

// Deprecated.
// TODO(asapersson): Remove.
#define RTC_HISTOGRAM_ENUMERATION_SPARSE(name, sample, boundary) \
  RTC_HISTOGRAM_COMMON_BLOCK_SLOW(name, sample, \
      webrtc::metrics::HistogramFactoryGetEnumeration(name, boundary))

// The name of the histogram should not vary.
// TODO(asapersson): Consider changing string to const char*.
#define RTC_HISTOGRAM_COMMON_BLOCK(constant_name, sample, \
                                   factory_get_invocation) \
  do { \
    static webrtc::metrics::Histogram* atomic_histogram_pointer = nullptr; \
    webrtc::metrics::Histogram* histogram_pointer = \
        rtc::AtomicOps::AcquireLoadPtr(&atomic_histogram_pointer); \
    if (!histogram_pointer) { \
      histogram_pointer = factory_get_invocation; \
      webrtc::metrics::Histogram* prev_pointer = \
          rtc::AtomicOps::CompareAndSwapPtr( \
              &atomic_histogram_pointer, \
              static_cast<webrtc::metrics::Histogram*>(nullptr), \
              histogram_pointer); \
      RTC_DCHECK(prev_pointer == nullptr || \
                 prev_pointer == histogram_pointer); \
    } \
    webrtc::metrics::HistogramAdd(histogram_pointer, constant_name, sample); \
  } while (0)

// Deprecated.
// The histogram is constructed/found for each call.
// May be used for histograms with infrequent updates.
#define RTC_HISTOGRAM_COMMON_BLOCK_SLOW(name, sample, factory_get_invocation) \
  do { \
    webrtc::metrics::Histogram* histogram_pointer = factory_get_invocation; \
    webrtc::metrics::HistogramAdd(histogram_pointer, name, sample); \
  } while (0)

namespace webrtc {
namespace metrics {

// Time that should have elapsed for stats that are gathered once per call.
enum { kMinRunTimeInSeconds = 10 };

class Histogram;

// Functions for getting pointer to histogram (constructs or finds the named
// histogram).

// Get histogram for counters.
Histogram* HistogramFactoryGetCounts(
    const std::string& name, int min, int max, int bucket_count);

// Get histogram for enumerators.
// |boundary| should be above the max enumerator sample.
Histogram* HistogramFactoryGetEnumeration(
    const std::string& name, int boundary);

// Function for adding a |sample| to a histogram.
// |name| can be used to verify that it matches the histogram name.
void HistogramAdd(
    Histogram* histogram_pointer, const std::string& name, int sample);

}  // namespace metrics
}  // namespace webrtc

#endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_METRICS_H_