From e64b6213365490b92923f757d9f9081d923a4723 Mon Sep 17 00:00:00 2001
From: Lars Strojny <lars@strojny.net>
Date: Wed, 9 Nov 2022 00:41:15 +0100
Subject: [PATCH] Mention where the escape functions come from

---
 src/prometheus.ts | 84 ++++++++++++++++++++++++-----------------------
 1 file changed, 43 insertions(+), 41 deletions(-)

diff --git a/src/prometheus.ts b/src/prometheus.ts
index ba8a1a8..de7e553 100644
--- a/src/prometheus.ts
+++ b/src/prometheus.ts
@@ -3,47 +3,6 @@ import { Logger } from 'homebridge'
 import { HttpResponse } from './adapters/http/api'
 import { HttpServer } from './http'
 
-function escapeString(str: string) {
-    return str.replace(/\\/g, '\\\\').replace(/\n/g, '\\n')
-}
-
-/**
- * String Attribute values are converted directly to Prometheus attribute values.
- * Non-string values are represented as JSON-encoded strings.
- *
- * `undefined` is converted to an empty string.
- */
-function escapeAttributeValue(str: string) {
-    if (typeof str !== 'string') {
-        str = JSON.stringify(str)
-    }
-    return escapeString(str).replace(/"/g, '\\"')
-}
-
-const invalidCharacterRegex = /[^a-z0-9_]/gi
-
-/**
- * Ensures metric names are valid Prometheus metric names by removing
- * characters allowed by OpenTelemetry but disallowed by Prometheus.
- *
- * https://prometheus.io/docs/concepts/data_model/#metric-names-and-attributes
- *
- * 1. Names must match `[a-zA-Z_:][a-zA-Z0-9_:]*`
- *
- * 2. Colons are reserved for user defined recording rules.
- * They should not be used by exporters or direct instrumentation.
- *
- * OpenTelemetry metric names are already validated in the Meter when they are created,
- * and they match the format `[a-zA-Z][a-zA-Z0-9_.\-]*` which is very close to a valid
- * prometheus metric name, so we only need to strip characters valid in OpenTelemetry
- * but not valid in prometheus and replace them with '_'.
- *
- * @param name name to be sanitized
- */
-function sanitizePrometheusMetricName(name: string): string {
-    return name.replace(invalidCharacterRegex, '_') // replace all invalid characters with '_'
-}
-
 export class MetricsRenderer {
     constructor(private readonly prefix: string) {}
 
@@ -128,3 +87,46 @@ export class PrometheusServer implements HttpServer {
         this.metricsInitialized = true
     }
 }
+
+// From https://github.com/open-telemetry/opentelemetry-js/blob/main/experimental/packages/opentelemetry-exporter-prometheus/src/PrometheusSerializer.ts
+
+function escapeString(str: string) {
+    return str.replace(/\\/g, '\\\\').replace(/\n/g, '\\n')
+}
+
+/**
+ * String Attribute values are converted directly to Prometheus attribute values.
+ * Non-string values are represented as JSON-encoded strings.
+ *
+ * `undefined` is converted to an empty string.
+ */
+function escapeAttributeValue(str: string) {
+    if (typeof str !== 'string') {
+        str = JSON.stringify(str)
+    }
+    return escapeString(str).replace(/"/g, '\\"')
+}
+
+const invalidCharacterRegex = /[^a-z0-9_]/gi
+
+/**
+ * Ensures metric names are valid Prometheus metric names by removing
+ * characters allowed by OpenTelemetry but disallowed by Prometheus.
+ *
+ * https://prometheus.io/docs/concepts/data_model/#metric-names-and-attributes
+ *
+ * 1. Names must match `[a-zA-Z_:][a-zA-Z0-9_:]*`
+ *
+ * 2. Colons are reserved for user defined recording rules.
+ * They should not be used by exporters or direct instrumentation.
+ *
+ * OpenTelemetry metric names are already validated in the Meter when they are created,
+ * and they match the format `[a-zA-Z][a-zA-Z0-9_.\-]*` which is very close to a valid
+ * prometheus metric name, so we only need to strip characters valid in OpenTelemetry
+ * but not valid in prometheus and replace them with '_'.
+ *
+ * @param name name to be sanitized
+ */
+function sanitizePrometheusMetricName(name: string): string {
+    return name.replace(invalidCharacterRegex, '_') // replace all invalid characters with '_'
+}