104 lines
4.1 KiB
Python
104 lines
4.1 KiB
Python
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"""In-memory Prometheus metrics registry.
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No prometheus_client dependency — formats text manually.
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"""
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from __future__ import annotations
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import threading
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from typing import Any
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def _labels_key(labels: dict[str, str]) -> tuple[tuple[str, str], ...]:
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return tuple(sorted(labels.items()))
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def _format_labels(labels: dict[str, str]) -> str:
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if not labels:
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return ""
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parts = ",".join(f'{k}="{v}"' for k, v in sorted(labels.items()))
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return "{" + parts + "}"
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class MetricsRegistry:
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"""Thread-safe in-memory metrics store with Prometheus text output."""
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def __init__(self) -> None:
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self._lock = threading.Lock()
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self._gauges: dict[str, dict[tuple[tuple[str, str], ...], float]] = {}
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self._counters: dict[str, dict[tuple[tuple[str, str], ...], float]] = {}
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self._histograms: dict[str, dict[tuple[tuple[str, str], ...], Any]] = {}
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def gauge(self, name: str, labels: dict[str, str], value: float) -> None:
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"""Set a gauge value."""
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key = _labels_key(labels)
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with self._lock:
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if name not in self._gauges:
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self._gauges[name] = {}
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self._gauges[name][key] = value
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def counter(self, name: str, labels: dict[str, str], increment: float = 1.0) -> None:
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"""Increment a counter."""
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key = _labels_key(labels)
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with self._lock:
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if name not in self._counters:
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self._counters[name] = {}
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self._counters[name][key] = self._counters[name].get(key, 0.0) + increment
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def histogram_observe(self, name: str, labels: dict[str, str], value: float) -> None:
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"""Record a histogram observation.
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Uses fixed buckets: 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 30, 60, 120, +Inf.
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"""
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key = _labels_key(labels)
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buckets = (0.01, 0.05, 0.1, 0.5, 1.0, 5.0, 10.0, 30.0, 60.0, 120.0)
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with self._lock:
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if name not in self._histograms:
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self._histograms[name] = {}
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if key not in self._histograms[name]:
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self._histograms[name][key] = {
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"labels": labels,
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"buckets": {b: 0 for b in buckets},
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"sum": 0.0,
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"count": 0,
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}
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entry = self._histograms[name][key]
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entry["sum"] += value
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entry["count"] += 1
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for b in buckets:
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if value <= b:
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entry["buckets"][b] += 1
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def render(self) -> str:
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"""Render all metrics in Prometheus text exposition format."""
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lines: list[str] = []
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with self._lock:
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for name, series in sorted(self._gauges.items()):
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lines.append(f"# TYPE {name} gauge")
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for key, val in sorted(series.items()):
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labels = dict(key)
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lines.append(f"{name}{_format_labels(labels)} {val}")
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for name, series in sorted(self._counters.items()):
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lines.append(f"# TYPE {name} counter")
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for key, val in sorted(series.items()):
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labels = dict(key)
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lines.append(f"{name}{_format_labels(labels)} {val}")
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for name, series in sorted(self._histograms.items()):
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lines.append(f"# TYPE {name} histogram")
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for _key, entry in sorted(series.items()):
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labels = entry["labels"]
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cumulative = 0
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for b, count in sorted(entry["buckets"].items()):
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cumulative += count
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le_labels = {**labels, "le": str(b)}
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lines.append(f"{name}_bucket{_format_labels(le_labels)} {cumulative}")
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inf_labels = {**labels, "le": "+Inf"}
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lines.append(f"{name}_bucket{_format_labels(inf_labels)} {entry['count']}")
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lines.append(f"{name}_sum{_format_labels(labels)} {entry['sum']}")
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lines.append(f"{name}_count{_format_labels(labels)} {entry['count']}")
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lines.append("")
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return "\n".join(lines)
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