Monotonic Counter

See Monotonic Counter for the concept.

Java does not expose a dedicated monotonic counter meter; the equivalent is the Polled Meter helper's monitorMonotonicCounter, which periodically samples a function returning the current absolute value and reports the per-second rate of the delta. A minimum of two polls is required before the first metric is reported.

Two common forms:

// Lambda over a source that exposes a long-valued cumulative count.
PolledMeter.using(registry)
    .withName("pool.completedTasks")
    .monitorMonotonicCounter(executor, ThreadPoolExecutor::getCompletedTaskCount);

// A Number instance that the caller updates directly.
LongAdder tasks = new LongAdder();
PolledMeter.using(registry)
    .withName("pool.completedTasks")
    .monitorMonotonicCounter(tasks);

For double-valued sources, use monitorMonotonicCounterDouble.

If the polled value decreases between samples (counter reset, source restart, or numeric wraparound), that interval's delta is dropped and the new value becomes the baseline for the next delta. See Counter resets and wraparounds.

Java is long-based, so there is no separate uint64 variant — monitorMonotonicCounter covers both signed and OS-counter use cases.