bdlm_metric.h

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/// @file bdlm_metric.h
///
/// The content of this file has been pre-processed for Doxygen.
///
 
 
// bdlm_metric.h                                                      -*-C++-*-
#ifndef INCLUDED_BDLM_METRIC
#define INCLUDED_BDLM_METRIC
 
#include <bsls_ident.h>
BSLS_IDENT("$Id$")
 
/// @defgroup bdlm_metric bdlm_metric
/// @brief  Provide a class to store metric values of different types.
/// @addtogroup bdl
/// @{
/// @addtogroup bdlm
/// @{
/// @addtogroup bdlm_metric
/// @{
///
/// <h1> Outline </h1>
/// * <a href="#bdlm_metric-purpose"> Purpose</a>
/// * <a href="#bdlm_metric-classes"> Classes </a>
/// * <a href="#bdlm_metric-description"> Description </a>
///   * <a href="#bdlm_metric-usage"> Usage </a>
///
/// # Purpose {#bdlm_metric-purpose}
/// Provide a class to store metric values of different types.
///
/// # Classes {#bdlm_metric-classes}
///
/// -  bdlm::Metric: variant of metric values
///
/// # Description {#bdlm_metric-description}
/// This component defines a value semantic class, `bdlmt::Metric`,
/// that represents a measurement (or measurements) for a metric.
/// A `bdlm::Metric` value is collected from an object that reports metrics
/// using a callback that is registered with the `bdlm::MetricsRegistry`.  A
/// `bdlm::Metric` value is a variant type, which can hold one of several types
/// of measurements (in theory).  Currently the only supported metric type is a
/// `Guage`, which represents a single instantaneous value for the most recent
/// measurement.
///
/// ## Usage {#bdlm_metric-usage}
///
///
/// The intended use of this component is illustrated in
/// {@ref bdlm_metricsregistrar |Usage}.
/// @}
/** @} */
/** @} */
 
/** @addtogroup bdl
 * @{
 */
/** @addtogroup bdlm
 * @{
 */
/** @addtogroup bdlm_metric
 * @{
 */
 
#include <bdlb_variant.h>
 
#include <bsls_assert.h>
 
 
namespace bdlm {
 
/// This class provides storage for various types of metric values.
///
/// See @ref bdlm_metric 
class Metric {
 
  public:
    // PUBLIC TYPES
    typedef double Gauge;
 
  private:
    // DATA
    bdlb::Variant<Gauge> d_value;  // value of the metric
 
    // FRIENDS
    friend bool operator==(const Metric& lhs, const Metric& rhs);
    friend bool operator!=(const Metric& lhs, const Metric& rhs);
 
  public:
    // CREATORS
 
    /// Create a default (empty) metric.
    Metric();
 
    /// Create a metric with the specified `value`.
    explicit Metric(const Gauge& value);
 
     ~Metric() = default;
        // Destroy this 'Metric' object.
 
    // MANIPULATORS
 
    /// Assign to this metric the specified `value`.
    Metric& operator=(const Gauge& value);
 
    // ACCESSORS
 
    /// Return `true` if the value of this metric is of gauge type, and
    /// `false` otherwise.
    bool isGauge() const;
 
    /// Return a `const` reference to the value of this metric of gauge type.  
    /// 
    /// \pre The behavior is undefined   unless `true == isGuage()`.
    const Gauge& theGauge() const;
};
 
// FREE OPERATORS
 
/// Return `true` if the specified `lhs` and `rhs` have the same value, and
/// `false` otherwise.  Two `Metric` objects have the same value if their
/// types are the same and they have the same value.
bool operator==(const Metric& lhs, const Metric& rhs);
 
/// Return `true` if the specified `lhs` command-line metric has a different
/// value from the specified `rhs` command-line metric, and `false`
/// otherwise.  Two `Metric` objects do not have the same value if their
/// types are not the same or they have different values.
bool operator!=(const Metric& lhs, const Metric& rhs);
 
// ============================================================================
//                             INLINE DEFINITIONS
// ============================================================================
 
                               // ------------
                               // class Metric
                               // ------------
 
// CREATORS
inline
Metric::Metric()
: d_value()
{
}
 
inline
Metric::Metric(const Gauge& value)
: d_value(value)
{
}
 
// MANIPULATORS
inline
Metric& Metric::operator=(const Gauge& value)
{
    d_value = value;
    return *this;
}
 
// ACCESSORS
inline
bool Metric::isGauge() const
{
    return d_value.is<Gauge>();
}
 
inline
const Metric::Gauge& Metric::theGauge() const
{
    BSLS_ASSERT(isGauge());
 
    return d_value.the<Gauge>();
}
 
// FREE OPERATORS
inline
bool operator==(const Metric& lhs, const Metric& rhs)
{
    return lhs.d_value == rhs.d_value;
}
 
inline
bool operator!=(const Metric& lhs, const Metric& rhs)
{
    return lhs.d_value != rhs.d_value;
}
 
}  // close package namespace
 
 
#endif
 
// ----------------------------------------------------------------------------
// Copyright 2024 Bloomberg Finance L.P.
//
// 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.
// ----------------------------- END-OF-FILE ----------------------------------
 
/** @} */
/** @} */
/** @} */