@metrics('loop').time()              # a common one to get the fps of each service. Gets us qty and time

  def frame():

      if err:

         metrics('foo_errors').incr()  # if you incr it, it's a counter

  @metrics('foo_calls').time()         # qty & time because it's a decorator

  def foo(): 

  metrics('goal_fps').set(f)           # a gauge because we called set()

  with metrics('recompute'): ...       # ctxmgr also makes a timer

     time_this_part()

I don't see a need for labels yet, but maybe some code will want like

metrics('foo', label1=one). Need histogram? Info?

"""

from typing import Dict, Tuple, Callable, Type, TypeVar, cast

import cyclone.web

from prometheus_client import Counter, Gauge, Metric, Summary

from prometheus_client.exposition import generate_latest

from prometheus_client.registry import REGISTRY

_created: Dict[str, Metric] = {}

# _process=sys.argv[0]

# def setProcess(name: str):

#   global _process

#   _process = name

MT = TypeVar("MT")

class _MetricsRequest:

    def __init__(self, name: str, **labels):

        self.name = name

        self.labels = labels

    def _ensure(self, cls: Type[MT]) -> MT:

        if self.name not in _created:

            _created[self.name] = cls(name=self.name, documentation=self.name, labelnames=self.labels.keys())

        m = _created[self.name]

        if self.labels:

            m = m.labels(**self.labels)

        return m

    def __call__(self, fn) -> Callable:

        return timed_fn

    def set(self, v: float):

        self._ensure(Gauge).set(v)

    def inc(self):

        self._ensure(Counter).inc()

    def offset(self, amount: float):

        self._ensure(Gauge).inc(amount)

    def time(self):

        return self._ensure(Summary).time()

    def observe(self, x: float):

        return self._ensure(Summary).observe(x)

    def __enter__(self):

        return self._ensure(Summary).__enter__()

def metrics(name: str, **labels):

    return _MetricsRequest(name, **labels)

class _CycloneMetrics(cyclone.web.RequestHandler):

    def get(self):

        self.add_header('content-type', 'text/plain')

        self.write(generate_latest(REGISTRY))

def metricsRoute() -> Tuple[str, Type[cyclone.web.RequestHandler]]:

    return ('/metrics', _CycloneMetrics)

"""

stuff we used to have in greplin. Might be nice to get (client-side-computed) min/max/stddev back.

class PmfStat(Stat):

  A stat that stores min, max, mean, standard deviation, and some

  percentiles for arbitrary floating-point data. This is potentially a

  bit expensive, so its child values are only updated once every

  twenty seconds.

i think prometheus covers this one:

import psutil

def gatherProcessStats():

    procStats = scales.collection('/process',

                                  scales.DoubleStat('time'),

                                  scales.DoubleStat('cpuPercent'),

                                  scales.DoubleStat('memMb'),

    )

    proc = psutil.Process()

    lastCpu = [0.]

    def updateTimeStat():

        now = time.time()

        procStats.time = round(now, 3)

        if now - lastCpu[0] > 3:

            procStats.cpuPercent = round(proc.cpu_percent(), 6) # (since last call)

            lastCpu[0] = now

        procStats.memMb = round(proc.memory_info().rss / 1024 / 1024, 6)

    task.LoopingCall(updateTimeStat).start(.1)

"""

class M:

    def __call__(self, name):

        return