Added basic metrics interfaces, a metrics factory and an implementation of those interfaces for Opentelemetry

Added a MetricsEngine that handles creation and registration of metrics

Author: Rentacookie

packages/service-core-tests/src/test-utils/metrics-utils.ts

@@ -0,0 +1,98 @@
+import { logger, ServiceAssertionError } from '@powersync/lib-services-framework';
+import { Counter, UpDownCounter, ObservableGauge, MetricMetadata, MetricsFactory } from './metrics-interfaces.js';
+
+export interface MetricsEngineOptions {
+  factory: MetricsFactory;
+  disable_telemetry_sharing: boolean;
+}
+
+export class MetricsEngine {
+  private counters: Map<string, Counter>;
+  private upDownCounters: Map<string, UpDownCounter>;
+  private observableGauges: Map<string, ObservableGauge>;
+
+  constructor(private options: MetricsEngineOptions) {
+    this.counters = new Map();
+    this.upDownCounters = new Map();
+    this.observableGauges = new Map();
+  }
+
+  private get factory(): MetricsFactory {
+    return this.options.factory;
+  }
+
+  createCounter(metadata: MetricMetadata): Counter {
+    if (this.counters.has(metadata.name)) {
+      logger.warn(`Counter with name ${metadata.name} already created and registered, skipping.`);
+      return this.counters.get(metadata.name)!;
+    }
+
+    const counter = this.factory.createCounter(metadata);
+    this.counters.set(metadata.name, counter);
+    return counter;
+  }
+  createUpDownCounter(metadata: MetricMetadata): UpDownCounter {
+    if (this.upDownCounters.has(metadata.name)) {
+      logger.warn(`UpDownCounter with name ${metadata.name} already created and registered, skipping.`);
+      return this.upDownCounters.get(metadata.name)!;
+    }
+
+    const upDownCounter = this.factory.createUpDownCounter(metadata);
+    this.upDownCounters.set(metadata.name, upDownCounter);
+    return upDownCounter;
+  }
+
+  createObservableGauge(metadata: MetricMetadata): ObservableGauge {
+    if (this.observableGauges.has(metadata.name)) {
+      logger.warn(`ObservableGauge with name ${metadata.name} already created and registered, skipping.`);
+      return this.observableGauges.get(metadata.name)!;
+    }
+
+    const observableGauge = this.factory.createObservableGauge(metadata);
+    this.observableGauges.set(metadata.name, observableGauge);
+    return observableGauge;
+  }
+
+  getCounter(name: string): Counter {
+    const counter = this.counters.get(name);
+    if (!counter) {
+      throw new ServiceAssertionError(`Counter '${name}' has not been created and registered yet.`);
+    }
+    return counter;
+  }
+
+  getUpDownCounter(name: string): UpDownCounter {
+    const upDownCounter = this.upDownCounters.get(name);
+    if (!upDownCounter) {
+      throw new ServiceAssertionError(`UpDownCounter '${name}' has not been created and registered yet.`);
+    }
+    return upDownCounter;
+  }
+
+  getObservableGauge(name: string): ObservableGauge {
+    const observableGauge = this.observableGauges.get(name);
+    if (!observableGauge) {
+      throw new ServiceAssertionError(`ObservableGauge '${name}' has not been created and registered yet.`);
+    }
+    return observableGauge;
+  }
+
+  public async start(): Promise<void> {
+    logger.info(
+      `
+Attention:
+PowerSync collects completely anonymous telemetry regarding usage.
+This information is used to shape our roadmap to better serve our customers.
+You can learn more, including how to opt-out if you'd not like to participate in this anonymous program, by visiting the following URL:
+https://docs.powersync.com/self-hosting/lifecycle-maintenance/telemetry
+    `.trim()
+    );
+    logger.info(`Anonymous telemetry is currently: ${this.options.disable_telemetry_sharing ? 'disabled' : 'enabled'}`);
+
+    logger.info('Successfully started Metrics Engine.');
+  }
+
+  public async shutdown(): Promise<void> {
+    logger.info('Successfully shut down Metrics Engine.');
+  }
+}

packages/service-core/src/metrics/Metrics.ts

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+export * from './MetricsEngine.js';
+export * from './metrics-interfaces.js';
+export * from './open-telemetry/OpenTelemetryMetricsFactory.js';
+export * from './open-telemetry/util.js';