feat(http): use high resolution timer for metrics

Author: blacha

package.json

@@ -40,7 +40,6 @@
     "build/src/**"
   ],
   "dependencies": {
-    "@linzjs/metrics": "^6.21.1",
     "find-my-way": "^7.0.0",
     "pino": "^8.3.0",
     "ulid": "^2.3.0"

src/http/router.ts

@@ -112,7 +112,6 @@ export class Router {
     }
 
     return Promise.race(requestHandles).then((res) => {
-      console.log('RaceDone', requestHandles);
       req.abort.abort();
       return finalize(req, res);
     });

src/metric.ts

@@ -0,0 +1,63 @@
+import { performance } from 'perf_hooks';
+
+/** Number of decimal places to keep in timers */
+const TruncateTimers = 4;
+/**
+ * Utility to record some metrics about the execution of the function
+ *
+ * TODO this should be replaced by open telemetry
+ */
+export class Metrics {
+  /**
+   * Start time of all timers
+   */
+  timers: Map<string, { start: number; duration?: number }> = new Map();
+
+  getTime(): number {
+    return performance.now();
+  }
+
+  /**
+   * Start a timer at the current time
+   * @param timeName name of timer to start
+   */
+  public start(timeName: string): void {
+    const existing = this.timers.get(timeName);
+    if (existing != null && existing.duration == null) {
+      throw new Error(`Duplicate startTime for "${timeName}"`);
+    }
+    this.timers.set(timeName, { start: this.getTime() });
+  }
+
+  /**
+   * End the timer, returning the duration in milliseconds
+   * @param timeName timer to end
+   */
+  public end(timeName: string): number {
+    const timer = this.timers.get(timeName);
+    if (timer == null) throw new Error(`Missing startTime information for "${timeName}"`);
+    const duration = this.getTime() - timer.start;
+    timer.duration = Number(duration.toFixed(TruncateTimers));
+    return duration;
+  }
+
+  /** Get list of all timers that have run */
+  public get metrics(): Record<string, number> | undefined {
+    if (this.timers.size === 0) return undefined;
+    const output: Record<string, number> = {};
+    for (const [key, timer] of this.timers.entries()) {
+      if (timer.duration != null) output[key] = timer.duration;
+    }
+    return output;
+  }
+
+  /** Get a list of timers that never finished */
+  public get unfinished(): string[] | undefined {
+    const st: string[] = [];
+    for (const [key, timer] of this.timers.entries()) {
+      if (timer.duration == null) st.push(key);
+    }
+    if (st.length === 0) return undefined;
+    return st;
+  }
+}

src/request.ts

@@ -1,4 +1,4 @@
-import { Metrics } from '@linzjs/metrics';
+import { Metrics } from './metric.js';
 import { Context } from 'aws-lambda';
 import { ulid } from 'ulid';
 import { LogType } from './log.js';

yarn.lock

@@ -52,11 +52,6 @@
   resolved "https://registry.yarnpkg.com/@humanwhocodes/object-schema/-/object-schema-1.2.1.tgz#b520529ec21d8e5945a1851dfd1c32e94e39ff45"
   integrity sha512-ZnQMnLV4e7hDlUvw8H+U8ASL02SS2Gn6+9Ac3wGGLIe7+je2AeAOxPY+izIPJDfFDb7eDjev0Us8MO1iFRN8hA==
 
-"@linzjs/metrics@^6.21.1":
-  version "6.21.1"
-  resolved "https://registry.yarnpkg.com/@linzjs/metrics/-/metrics-6.21.1.tgz#58d008c6b9c26400ea9934e2b07bc7f3dbcdd6d7"
-  integrity sha512-3QupitQN91FwxBN+EEmlBRIcLEwoOG/RK+T2yZtIHuFxXmaPJabnVFnJG62/uzlMZw8gRwmyixUg5qTVuSnziQ==
-
 "@linzjs/style@^3.9.0":
   version "3.9.0"
   resolved "https://registry.yarnpkg.com/@linzjs/style/-/style-3.9.0.tgz#a4df77d78dc5434e57ba8106ca188b1b8bf03143"