[VM/Service] Add private _invalidateIdZone RPC

TEST=pkg/vm_service/test/id_zones_test.dart, CI

Issue: https://github.com/dart-lang/sdk/issues/55869
Change-Id: I02fcb2502b698066885b3f090435e43a34ed6fcd
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/379820
Reviewed-by: Ben Konyi <bkonyi@google.com>

pkg/vm_service/test/id_zones_test.dart

@@ -85,6 +85,36 @@ final tests = <IsolateTest>[
 
     final cInstance2 = await service.getObject(isolateId, cObjectId2);
     expect(cInstance2.type, 'Instance');
+
+    await service.callMethod(
+      '_invalidateIdZone',
+      isolateId: isolateId,
+      args: {
+        '_idZoneId': idZone1['id'],
+      },
+    );
+
+    try {
+      await service.getObject(isolateId, cObjectId1);
+      fail('successfully retrieved object using expired ID');
+    } on SentinelException catch (e) {
+      expect(e.sentinel.kind, startsWith('Expired'));
+      expect(e.sentinel.valueAsString, equals('<expired>'));
+    }
+
+    // Ensure that the zone can be reused after it was invalidated.
+    final cInstanceRef3 = (await service.callMethod(
+      'evaluateInFrame',
+      isolateId: isolateId,
+      args: {
+        'frameIndex': 0,
+        'expression': 'c',
+        '_idZoneId': idZone1['id'],
+      },
+    ))
+        .json!;
+    expect(cInstanceRef3['type'], '@Instance');
+    expect(cInstanceRef3['id'], 'objects/0/1');
   },
 
   // Test the behaviour of an ID Zone with a `backingBufferKind` of `Ring`, an
@@ -202,6 +232,36 @@ final tests = <IsolateTest>[
 
     final cInstance2 = await service.getObject(isolateId, cObjectId2);
     expect(cInstance2.type, 'Instance');
+
+    await service.callMethod(
+      '_invalidateIdZone',
+      isolateId: isolateId,
+      args: {
+        '_idZoneId': idZone3['id'],
+      },
+    );
+
+    try {
+      await service.getObject(isolateId, cObjectId1);
+      fail('successfully retrieved object using expired ID');
+    } on SentinelException catch (e) {
+      expect(e.sentinel.kind, startsWith('Expired'));
+      expect(e.sentinel.valueAsString, equals('<expired>'));
+    }
+
+    // Ensure that the zone can be reused after it was invalidated.
+    final cInstanceRef3 = (await service.callMethod(
+      'evaluateInFrame',
+      isolateId: isolateId,
+      args: {
+        'frameIndex': 0,
+        'expression': 'c',
+        '_idZoneId': idZone3['id'],
+      },
+    ))
+        .json!;
+    expect(cInstanceRef3['type'], '@Instance');
+    expect(cInstanceRef3['id'], 'objects/0/3');
   },
   resumeIsolate,
 ];

runtime/vm/object_id_ring.cc

@@ -18,9 +18,17 @@ ObjectIdRing::~ObjectIdRing() {
   table_ = nullptr;
 }
 
+void ObjectIdRing::Invalidate() {
+  serial_num_ = 0;
+  wrapped_ = false;
+  for (int32_t i = 0; i < capacity_; i++) {
+    table_[i] = Object::null();
+  }
+}
+
 int32_t ObjectIdRing::GetIdForObject(ObjectPtr object, IdPolicy policy) {
-  // We do not allow inserting null because null is how we detect as entry was
-  // reclaimed by the GC.
+  // We do not allow inserting |Object::null()| because we use it as a
+  // placeholder for unpopulated slots in |table_|.
   ASSERT(object != Object::null());
   if (policy == kAllocateId) {
     return AllocateNewId(object);
@@ -51,10 +59,9 @@ ObjectPtr ObjectIdRing::GetObjectForId(int32_t id, LookupResult* kind) {
   }
   ASSERT(index >= 0);
   ASSERT(index < capacity_);
-  if (table_[index] == Object::null()) {
-    *kind = kCollected;
-    return Object::null();
-  }
+  // The `index == kInvalidId` check above should make it impossible for
+  // `table_[index]` to be |Object::null()|.
+  ASSERT(table_[index] != Object::null());
   *kind = kValid;
   ASSERT(IdOfIndex(index) == id);
   return table_[index];

runtime/vm/object_id_ring.h

@@ -44,6 +44,9 @@ class ObjectIdRing {
   explicit ObjectIdRing(int32_t capacity);
   ~ObjectIdRing();
 
+  // Invalidate all the Service IDs currently living in this ring.
+  void Invalidate();
+
   // Adds the argument to the ring and returns its id. Note we do not allow
   // adding Object::null().
   int32_t GetIdForObject(ObjectPtr raw_obj, IdPolicy policy = kAllocateId);

runtime/vm/service.cc

@@ -395,6 +395,10 @@ char* RingServiceIdZone::GetServiceId(const Object& obj) {
                              id());
 }
 
+void RingServiceIdZone::Invalidate() {
+  ring_.Invalidate();
+}
+
 void RingServiceIdZone::VisitPointers(ObjectPointerVisitor& visitor) const {
   ring_.VisitPointers(&visitor);
 }
@@ -2682,6 +2686,23 @@ static void GetReachableSize(Thread* thread, JSONStream* js) {
   result.PrintJSON(js, true);
 }
 
+static const MethodParameter* const invalidate_id_zone_params[] = {
+    RUNNABLE_ISOLATE_PARAMETER,
+    nullptr,
+};
+
+static void InvalidateIdZone(Thread* thread, JSONStream* js) {
+  ASSERT(thread != nullptr);
+  ASSERT(js != nullptr);
+
+  Isolate* isolate = thread->isolate();
+  ASSERT(isolate != nullptr);
+
+  js->id_zone().Invalidate();
+
+  PrintSuccess(js);
+}
+
 static const MethodParameter* const invoke_params[] = {
     RUNNABLE_ISOLATE_PARAMETER,
     nullptr,
@@ -6087,6 +6108,8 @@ static const ServiceMethodDescriptor service_methods_[] = {
     get_vm_timeline_flags_params },
   { "getVMTimelineMicros", GetVMTimelineMicros,
     get_vm_timeline_micros_params },
+  { "_invalidateIdZone", InvalidateIdZone,
+    invalidate_id_zone_params },
   { "invoke", Invoke, invoke_params },
   { "kill", Kill, kill_params },
   { "pause", Pause,

runtime/vm/service.h

@@ -48,6 +48,8 @@ class ServiceIdZone {
                                    ObjectIdRing::LookupResult* kind) = 0;
   // Returned string will be zone allocated.
   virtual char* GetServiceId(const Object& obj) = 0;
+  // Invalidate all the Service IDs currently living in this zone.
+  virtual void Invalidate() = 0;
   virtual void VisitPointers(ObjectPointerVisitor& visitor) const = 0;
 
   virtual void PrintJSON(JSONStream& js) const = 0;
@@ -77,6 +79,7 @@ class RingServiceIdZone final : public ServiceIdZone {
   ObjectPtr GetObjectForId(int32_t id, ObjectIdRing::LookupResult* kind) final;
   // Returned string will be zone allocated.
   char* GetServiceId(const Object& obj) final;
+  void Invalidate() final;
   void VisitPointers(ObjectPointerVisitor& visitor) const final;
 
   void PrintJSON(JSONStream& js) const final;