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

#pragma once

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

#include <memory>
#include <utility>

namespace beast::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() = default;

    /**
     * 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> impl) : impl_(std::move(impl))
    {
    }

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

}  // namespace beast::insight