rippled/include/xrpl/beast/insight/Counter.h

#ifndef BEAST_INSIGHT_COUNTER_H_INCLUDED
#define BEAST_INSIGHT_COUNTER_H_INCLUDED

#include <xrpl/beast/insight/CounterImpl.h>

#include <memory>

namespace beast {
namespace insight {

/** A metric for measuring an integral value.

    A counter is a gauge calculated at the server. The owner of the counter
    may increment and decrement the value by an amount.

    This is a lightweight reference wrapper which is cheap to copy and assign.
    When the last reference goes away, the metric is no longer collected.
*/
class Counter final
{
public:
    using value_type = CounterImpl::value_type;

    /** Create a null metric.
        A null metric reports no information.
    */
    Counter()
    {
    }

    /** Create the metric reference the specified implementation.
        Normally this won't be called directly. Instead, call the appropriate
        factory function in the Collector interface.
        @see Collector.
    */
    explicit Counter(std::shared_ptr<CounterImpl> const& impl) : m_impl(impl)
    {
    }

    /** Increment the counter. */
    /** @{ */
    void
    increment(value_type amount) const
    {
        if (m_impl)
            m_impl->increment(amount);
    }

    Counter const&
    operator+=(value_type amount) const
    {
        increment(amount);
        return *this;
    }

    Counter const&
    operator-=(value_type amount) const
    {
        increment(-amount);
        return *this;
    }

    Counter const&
    operator++() const
    {
        increment(1);
        return *this;
    }

    Counter const&
    operator++(int) const
    {
        increment(1);
        return *this;
    }

    Counter const&
    operator--() const
    {
        increment(-1);
        return *this;
    }

    Counter const&
    operator--(int) const
    {
        increment(-1);
        return *this;
    }

private:
    std::shared_ptr<CounterImpl> m_impl;
};

}  // namespace insight
}  // namespace beast

#endif