[dds/dap] Handle "Service has disappeared" errors for in-flight requests when app may be shutting down

Fixes https://github.com/flutter/flutter/issues/116235.

Change-Id: Ibfd24bce45519116e350a7f409609f19ca502ad3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/303580
Reviewed-by: Ben Konyi <bkonyi@google.com>
Commit-Queue: Ben Konyi <bkonyi@google.com>

pkg/dds/CHANGELOG.md

@@ -1,3 +1,6 @@
+# 2.8.2
+- [DAP] Fixed an issue that could result in unhandled exceptions from in-flight requests when the application/VM Service is shutting down.
+
 # 2.8.1
 - Updated DDS protocol version to 1.5.
 - Added `getPerfettoVMTimelineWithCpuSamples` RPC.

pkg/dds/lib/src/dap/adapters/dart.dart

@@ -2425,17 +2425,29 @@ abstract class DartDebugAdapter<TL extends LaunchRequestArguments,
     try {
       return await func();
     } on vm.RPCError catch (e) {
-      // If we've been asked to shut down while this request was occurring,
-      // it's normal to get some types of errors from in-flight VM Service
-      // requests and we should handle them silently.
-      if (isTerminating) {
-        // kServiceDisappeared is thrown sometimes when services disappear.
-        if (e.code == RpcErrorCodes.kServiceDisappeared) {
+      // kServiceDisappeared is thrown sometimes when the VM Service is
+      // shutting down. Usually this is because we're shutting down (and
+      // `isTerminating` is true), but it can also happen if the app is closed
+      // outside of the DAP (eg. closing the simulator) so it's possible our
+      // requests will fail in this way before we've handled any event to set
+      // `isTerminating`.
+      if (e.code == RpcErrorCodes.kServiceDisappeared) {
+        return null;
+      }
+
+      // For any other kind of server error, ignore it if we're shutting down
+      // (because lots of requests can generate all sorts of errors if the VM
+      // and Isolates are shutting down), or if it's a "client closed with
+      // pending request" error (which also indicates a shutdown, but as above,
+      // we might not have set `isTerminating` yet).
+      if (e.code == json_rpc_errors.SERVER_ERROR) {
+        // Ignore all server errors during shutdown.
+        if (isTerminating) {
           return null;
         }
-        // SERVER_ERROR can occur when DDS completes any outstanding requests
-        // with "The client closed with pending request".
-        if (e.code == json_rpc_errors.SERVER_ERROR) {
+
+        // Always ignore "closed with pending request" errors.
+        if (e.message.contains("The client closed with pending request")) {
           return null;
         }
       }

pkg/dds/pubspec.yaml

@@ -1,5 +1,5 @@
 name: dds
-version: 2.8.1
+version: 2.8.2
 description: >-
   A library used to spawn the Dart Developer Service, used to communicate with
   a Dart VM Service instance.

pkg/dds/test/dap/integration/debug_test.dart

@@ -372,12 +372,12 @@ main() {
     test('can shutdown during startup', () async {
       final testFile = dap.createTestFile(simpleArgPrintingProgram);
 
-      // Terminate the app immediately upon receiving the first Thread event.
+      // Request termination immediately upon receiving the first Thread event.
       // The DAP is also responding to this event to configure the isolate (eg.
       // set breakpoints and exception pause behaviour) and will cause it to
       // receive "Service has disappeared" responses if these are in-flight as
-      // the process terminates. These should not go unhandled since they are
-      // normal during shutdown.
+      // the process terminates. These should be silently discarded since they
+      // are normal during shutdown.
       unawaited(dap.client.event('thread').then((_) => dap.client.terminate()));
 
       // Start the program and expect termination.