This adds a mechanism to invalidate code that was generated in the background. The invalidation can…

runtime/vm/compiler.h

 // Copyright (c) 2012, 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_COMPILER_H_
 #define VM_COMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/growable_array.h"
 #include "vm/runtime_entry.h"
 #include "vm/thread_pool.h"
 
 namespace dart {
 
 // Forward declarations.
 class Class;
 class Code;
+class CompilationWorkQueue;
 class Function;
 class Library;
 class ParsedFunction;
 class RawInstance;
 class Script;
 class SequenceNode;
 
+// Carries result from background compilation: code and generation counters
+// that help check if the code may have become invalid during background
+// compilation.
+class BackgroundCompilationResult : public ValueObject {
+ public:
+  BackgroundCompilationResult();
+
+  // Initializes with current isolate-stored generations
+  void Init();
+
+  void set_result_code(const Code& value) { result_code_ = value.raw(); }
+  const Code& result_code() const { return result_code_; }
+
+  // Returns true if all relevant gen-counts are current and code is valid.
+  bool IsValid() const;
+
+  // Remove gen-counts from validation check.
+  void ClearCHAInvalidationGen() {
+    cha_invalidation_gen_ = Integer::null();
+  }
+  void ClearFieldInnvalidationGen() {
+    field_invalidation_gen_ = Integer::null();
+  }
+  void ClearPrefixInnvalidationGen() {
+    prefix_invalidation_gen_ = Integer::null();
+  }
+
+  void PushOnQueue(CompilationWorkQueue* queue) const;
+  void PopFromQueue(CompilationWorkQueue* queue);
+
+  void PrintValidity() const;
+
+ private:
+  Code& result_code_;
+  Integer& cha_invalidation_gen_;
+  Integer& field_invalidation_gen_;
+  Integer& prefix_invalidation_gen_;
+};
+
+
 class Compiler : public AllStatic {
  public:
   static const intptr_t kNoOSRDeoptId = Thread::kNoDeoptId;
 
   static bool IsBackgroundCompilation();
 
   // Extracts top level entities from the script and populates
   // the class dictionary of the library.
   //
   // Returns Error::null() if there is no compilation error.
@@ skipping 16 matching lines @@
 
   // Generates optimized code for function.
   //
   // Returns Error::null() if there is no compilation error.
   // If 'result_code' is not NULL, then the generated code is returned but
   // not installed.
   static RawError* CompileOptimizedFunction(
       Thread* thread,
       const Function& function,
       intptr_t osr_id = kNoOSRDeoptId,
-      Code* result_code = NULL);
+      BackgroundCompilationResult* res = NULL);
 
   // Generates code for given parsed function (without parsing it again) and
   // sets its code field.
   //
   // Returns Error::null() if there is no compilation error.
   static RawError* CompileParsedFunction(ParsedFunction* parsed_function);
 
   // Generates and executes code for a given code fragment, e.g. a
   // compile time constant expression. Returns the result returned
   // by the fragment.
@@ skipping 57 matching lines @@
   // Access to queue length is guarded with queue_monitor_;
   intptr_t function_queue_length() const { return function_queue_length_; }
   void set_function_queue_length(intptr_t value) {
     function_queue_length_ = value;
   }
 
  private:
   explicit BackgroundCompiler(Isolate* isolate);
 
   GrowableObjectArray* FunctionsQueue() const;
-  GrowableObjectArray* CodesQueue() const;
+  GrowableObjectArray* ResultQueue() const;
 
   virtual void Run();
 
   void AddFunction(const Function& f);
   RawFunction* RemoveFunctionOrNull();
   RawFunction* LastFunctionOrNull() const;
 
-  void AddCode(const Code& c);
+  void AddResult(const BackgroundCompilationResult& value);
 
   Isolate* isolate_;
   bool running_;       // While true, will try to read queue and compile.
   bool* done_;         // True if the thread is done.
   Monitor* queue_monitor_;  // Controls access to the queue.
   Monitor* done_monitor_;   // Notify/wait that the thread is done.
 
   // Lightweight access to length of compiler queue.
   intptr_t function_queue_length_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BackgroundCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_COMPILER_H_