Track loading happening in parallel with background compilation and abort compilation if necessary.

runtime/vm/isolate.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 469 matching lines @@
   void set_compilation_allowed(bool allowed) {
     compilation_allowed_ = allowed;
   }
 
   // In precompilation we finalize all regular classes before compiling.
   bool all_classes_finalized() const { return all_classes_finalized_; }
   void set_all_classes_finalized(bool value) {
     all_classes_finalized_ = value;
   }
 
+  // True during top level parsing.
+  bool top_level_parsing() const { return top_level_parsing_; }
+  void set_top_level_parsing(bool value) { top_level_parsing_ = value; }
+
   static const uint32_t kInvalidGen = 0;
 
-  void IncrCHAInvalidationGen() {
-    cha_invalidation_gen_++;
-    if (cha_invalidation_gen_ == kInvalidGen) cha_invalidation_gen_++;
-  }
-  void ResetCHAInvalidationGen() { cha_invalidation_gen_ = kInvalidGen; }
-  uint32_t cha_invalidation_gen() const { return cha_invalidation_gen_; }
-
-
   void IncrFieldInvalidationGen() {
     field_invalidation_gen_++;
     if (field_invalidation_gen_ == kInvalidGen) field_invalidation_gen_++;
   }
 
   void ResetFieldInvalidationGen() { field_invalidation_gen_ = kInvalidGen; }
   uint32_t field_invalidation_gen() const { return field_invalidation_gen_; }
 
-  void IncrPrefixInvalidationGen() {
-    prefix_invalidation_gen_++;
-    if (prefix_invalidation_gen_ == kInvalidGen) prefix_invalidation_gen_++;
+  void IncrLoadingInvalidationGen() {
+    loading_invalidation_gen_++;
+    if (loading_invalidation_gen_ == kInvalidGen) loading_invalidation_gen_++;

[siva, 2016/03/28 17:20:14]

Why are you first incrementing and then checking, won't the check always fail?

Since these values are accessed from another thread, I am wondering if we should
be doing atomic increment operations here.

[srdjan, 2016/03/28 19:54:54]

Since we never reset the count, we may overflow and encounter kInvalidGen again.
Removed unused ResetXXGen.

Yes for atomic operations.

   }
-  void ResetPrefixInvalidationGen() { prefix_invalidation_gen_ = kInvalidGen; }
-  uint32_t prefix_invalidation_gen() const { return prefix_invalidation_gen_; }
+  void ResetLoadingInvalidationGen() {
+    loading_invalidation_gen_ = kInvalidGen;
+  }
+  uint32_t loading_invalidation_gen() const {
+    return loading_invalidation_gen_;
+  }
 
   // Used by background compiler which field became boxed and must trigger
   // deoptimization in the mutator thread.
   void AddDeoptimizingBoxedField(const Field& field);
   // Returns Field::null() if none available in the list.
   RawField* GetDeoptimizingBoxedField();
 
   RawObject* InvokePendingServiceExtensionCalls();
   void AppendServiceExtensionCall(const Instance& closure,
                            const String& method_name,
@@ skipping 189 matching lines @@
     kRegisteredNameIndex = 0,
     kRegisteredHandlerIndex,
     kRegisteredEntrySize
   };
   RawGrowableObjectArray* registered_service_extension_handlers_;
 
   Metric* metrics_list_head_;
 
   bool compilation_allowed_;
   bool all_classes_finalized_;
+  bool top_level_parsing_;
 
   // Isolate list next pointer.
   Isolate* next_;
 
   // Used to wake the isolate when it is in the pause event loop.
   Monitor* pause_loop_monitor_;
 
   // Invalidation generations; used to track events occuring in parallel
   // to background compilation. The counters may overflow, which is OK
   // since we check for equality to detect if an event occured.
-  uint32_t cha_invalidation_gen_;
   uint32_t field_invalidation_gen_;
-  uint32_t prefix_invalidation_gen_;
+  uint32_t loading_invalidation_gen_;
 
   // Protect access to boxed_field_list_.
   Mutex* boxed_field_list_mutex_;
   // List of fields that became boxed and that trigger deoptimization.
   RawGrowableObjectArray* boxed_field_list_;
 
   // This guards spawn_count_. An isolate cannot complete shutdown and be
   // destroyed while there are child isolates in the midst of a spawn.
   Monitor* spawn_count_monitor_;
   intptr_t spawn_count_;
@@ skipping 157 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_