Bailout if field state changed during background compilation.

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"
@@ skipping 76 matching lines @@
   // Generates local var descriptors and sets it in 'code'. Do not call if the
   // local var descriptor already exists.
   static void ComputeLocalVarDescriptors(const Code& code);
 
   // Eagerly compiles all functions in a class.
   //
   // Returns Error::null() if there is no compilation error.
   static RawError* CompileAllFunctions(const Class& cls);
 
   static bool always_optimize();
+
+  static void AbortBackgroundCompilation(intptr_t deopt_id);

[rmacnak, 2016/02/08 20:24:25]

Add comment that this is a transient failure for when the mutator changes state
we are using in a background compilation and we may retry the compilation later.

[srdjan, 2016/02/08 20:30:16]

  // Notify the compiler that background (optimized) compilation has failed
  // because the mutator thread changed the state (e.g., deoptimization,
  // deferred loading). The background compilation may retry to compile
  // the same function later.

 };
 
 
 // Class to run optimizing compilation in a background thread.
 // Current implementation: one task per isolate, it dies with the owning
 // isolate.
 // No OSR compilation in the background compiler.
 class BackgroundCompiler : public ThreadPool::Task {
  public:
   static void EnsureInit(Thread* thread);
@@ skipping 20 matching lines @@
   Monitor* done_monitor_;   // Notify/wait that the thread is done.
 
   BackgroundCompilationQueue* function_queue_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(BackgroundCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_COMPILER_H_