refactor(instr-undici): avoid use of deprecated APIs for diagnostic channels

plugins/node/instrumentation-undici/src/internal-types.ts

@@ -13,14 +13,12 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import type { Channel } from 'diagnostics_channel';
 
 import { UndiciRequest, UndiciResponse } from './types';
 
 export interface ListenerRecord {
   name: string;
-  channel: Channel;
-  onMessage: (message: any, name: string | symbol) => void;
+  unsubscribe: () => void;
 }
 
 export interface RequestMessage {

plugins/node/instrumentation-undici/src/undici.ts

@@ -77,7 +77,7 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
 
   override disable(): void {
     super.disable();
-    this._channelSubs.forEach(sub => sub.channel.unsubscribe(sub.onMessage));
+    this._channelSubs.forEach(sub => sub.unsubscribe());
     this._channelSubs.length = 0;
   }
 
@@ -137,14 +137,29 @@ export class UndiciInstrumentation extends InstrumentationBase<UndiciInstrumenta
 
   private subscribeToChannel(
     diagnosticChannel: string,
-    onMessage: ListenerRecord['onMessage']
+    onMessage: (message: any, name: string | symbol) => void
   ) {
-    const channel = diagch.channel(diagnosticChannel);
-    channel.subscribe(onMessage);
+    // `diagnostics_channel` had a ref counting bug until v18.19.0.
+    // https://github.com/nodejs/node/pull/47520
+    const [major, minor] = process.version
+      .replace('v', '')
+      .split('.')
+      .map(n => Number(n));
+    const useNewSubscribe = major > 18 || (major === 18 && minor >= 19);
+
+    let unsubscribe: () => void;
+    if (useNewSubscribe) {
+      diagch.subscribe?.(diagnosticChannel, onMessage);
+      unsubscribe = () => diagch.unsubscribe?.(diagnosticChannel, onMessage);
+    } else {
+      const channel = diagch.channel(diagnosticChannel);
+      channel.subscribe(onMessage);
+      unsubscribe = () => channel.unsubscribe(onMessage);
+    }
+
     this._channelSubs.push({
       name: diagnosticChannel,
-      channel,
-      onMessage,
+      unsubscribe,
     });
   }