fix(instrumentation-pg): ensure db.client.operation.duration metric is recorded for Promises API usage of pg (open-telemetry#2480)

Refs: open-telemetry#2380

Author: trentm

plugins/node/opentelemetry-instrumentation-pg/src/instrumentation.ts

@@ -414,6 +414,7 @@ export class PgInstrumentation extends InstrumentationBase<PgInstrumentationConf
               // Return a pass-along promise which ends the span and then goes to user's orig resolvers
               return new Promise(resolve => {
                 utils.handleExecutionResult(plugin.getConfig(), span, result);
+                recordDuration();
                 span.end();
                 resolve(result);
               });
@@ -424,6 +425,7 @@ export class PgInstrumentation extends InstrumentationBase<PgInstrumentationConf
                   code: SpanStatusCode.ERROR,
                   message: error.message,
                 });
+                recordDuration();
                 span.end();
                 reject(error);
               });

plugins/node/opentelemetry-instrumentation-pg/test/pg-pool.test.ts

@@ -51,9 +51,10 @@ import {
   SEMATTRS_DB_STATEMENT,
 } from '@opentelemetry/semantic-conventions';
 import {
+  ATTR_DB_CLIENT_CONNECTION_STATE,
   METRIC_DB_CLIENT_CONNECTION_COUNT,
   METRIC_DB_CLIENT_CONNECTION_PENDING_REQUESTS,
-  ATTR_DB_CLIENT_CONNECTION_STATE,
+  METRIC_DB_CLIENT_OPERATION_DURATION,
 } from '@opentelemetry/semantic-conventions/incubating';
 
 const memoryExporter = new InMemorySpanExporter();
@@ -524,6 +525,11 @@ describe('pg-pool', () => {
           );
 
           const metrics = resourceMetrics.scopeMetrics[0].metrics;
+          assert.strictEqual(
+            metrics[0].descriptor.name,
+            METRIC_DB_CLIENT_OPERATION_DURATION
+          );
+
           assert.strictEqual(
             metrics[1].descriptor.name,
             METRIC_DB_CLIENT_CONNECTION_COUNT
@@ -573,6 +579,40 @@ describe('pg-pool', () => {
       });
     });
 
+    it('should generate `db.client.*` metrics (Promises-style)', async (...args) => {
+      const client = await pool.connect();
+
+      try {
+        const ret = await client.query('SELECT NOW()');
+        assert.ok(ret);
+      } finally {
+        client.release();
+      }
+
+      const { resourceMetrics, errors } = await metricReader.collect();
+      assert.deepEqual(
+        errors,
+        [],
+        'expected no errors from the callback during metric collection'
+      );
+
+      // We just test the expected metric *names* here. The particulars of the
+      // metric values are already tested in other test cases.
+      const metrics = resourceMetrics.scopeMetrics[0].metrics;
+      assert.strictEqual(
+        metrics[0].descriptor.name,
+        METRIC_DB_CLIENT_OPERATION_DURATION
+      );
+      assert.strictEqual(
+        metrics[1].descriptor.name,
+        METRIC_DB_CLIENT_CONNECTION_COUNT
+      );
+      assert.strictEqual(
+        metrics[2].descriptor.name,
+        METRIC_DB_CLIENT_CONNECTION_PENDING_REQUESTS
+      );
+    });
+
     it('should not add duplicate event listeners to PgPool events', done => {
       const poolAux: pgPool<pg.Client> = new pgPool(CONFIG);
       let completed = 0;