Enable export lookup by two threads (mutator and background compiler) by carying a copy of exports_…

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 9481 matching lines @@
   }
 
   // Invalidate the cache of loaded scripts.
   if (loaded_scripts() != Array::null()) {
     StorePointer(&raw_ptr()->loaded_scripts_, Array::null());
   }
 }
 
 
 // Lookup a name in the library's re-export namespace.
+// This lookup can occur from two different threads: background compiler and
+// mutator thread.
 RawObject* Library::LookupReExport(const String& name) const {
   if (HasExports()) {
-    const Array& exports = Array::Handle(this->exports());
-    // Break potential export cycle while looking up name.
-    StorePointer(&raw_ptr()->exports_, Object::empty_array().raw());
+    const bool is_background_compiler = Compiler::IsBackgroundCompilation();
+    Array& exports = Array::Handle();
+    if (is_background_compiler) {
+      exports = this->exports2();
+      // Break potential export cycle while looking up name.
+      StorePointer(&raw_ptr()->exports2_, Object::empty_array().raw());
+    } else {
+      exports = this->exports();
+      // Break potential export cycle while looking up name.
+      StorePointer(&raw_ptr()->exports_, Object::empty_array().raw());
+    }
     Namespace& ns = Namespace::Handle();
     Object& obj = Object::Handle();
     for (int i = 0; i < exports.Length(); i++) {
       ns ^= exports.At(i);
       obj = ns.Lookup(name);
       if (!obj.IsNull()) {
         // The Lookup call above may return a setter x= when we are looking
         // for the name x. Make sure we only return when a matching name
         // is found.
         String& obj_name = String::Handle(obj.DictionaryName());
         if (Field::IsSetterName(obj_name) == Field::IsSetterName(name)) {
           break;
         }
       }
     }
-    StorePointer(&raw_ptr()->exports_, exports.raw());
+    if (is_background_compiler) {
+      StorePointer(&raw_ptr()->exports2_, exports.raw());
+    } else {
+      StorePointer(&raw_ptr()->exports_, exports.raw());
+    }
     return obj.raw();
   }
   return Object::null();
 }
 
 
 RawObject* Library::LookupEntry(const String& name, intptr_t *index) const {
   Thread* thread = Thread::Current();
   REUSABLE_ARRAY_HANDLESCOPE(thread);
   REUSABLE_OBJECT_HANDLESCOPE(thread);
@@ skipping 426 matching lines @@
       }
     }
   }
   return false;
 }
 
 
 void Library::DropDependencies() const {
   StorePointer(&raw_ptr()->imports_, Array::null());
   StorePointer(&raw_ptr()->exports_, Array::null());
+  StorePointer(&raw_ptr()->exports2_, Array::null());
 }
 
 
 void Library::AddImport(const Namespace& ns) const {
   Array& imports = Array::Handle(this->imports());
   intptr_t capacity = imports.Length();
   if (num_imports() == capacity) {
     capacity = capacity + kImportsCapacityIncrement;
     imports = Array::Grow(imports, capacity);
     StorePointer(&raw_ptr()->imports_, imports.raw());
@@ skipping 12 matching lines @@
 
 
 // We add one namespace at a time to the exports array and don't
 // pre-allocate any unused capacity. The assumption is that
 // re-exports are quite rare.
 void Library::AddExport(const Namespace& ns) const {
   Array &exports = Array::Handle(this->exports());
   intptr_t num_exports = exports.Length();
   exports = Array::Grow(exports, num_exports + 1);
   StorePointer(&raw_ptr()->exports_, exports.raw());
+  StorePointer(&raw_ptr()->exports2_, exports.raw());
   exports.SetAt(num_exports, ns);
 }
 
 
 static RawArray* NewDictionary(intptr_t initial_size) {
   const Array& dict = Array::Handle(Array::New(initial_size + 1, Heap::kOld));
   // The last element of the dictionary specifies the number of in use slots.
   dict.SetAt(initial_size, Smi::Handle(Smi::New(0)));
   return dict.raw();
 }
@@ skipping 47 matching lines @@
   result.StorePointer(&result.raw_ptr()->dictionary_,
                       Object::empty_array().raw());
   result.StorePointer(&result.raw_ptr()->metadata_,
                       GrowableObjectArray::New(4, Heap::kOld));
   result.StorePointer(&result.raw_ptr()->toplevel_class_, Class::null());
   result.StorePointer(&result.raw_ptr()->patch_classes_,
                       GrowableObjectArray::New(Object::empty_array(),
                                                Heap::kOld));
   result.StorePointer(&result.raw_ptr()->imports_, Object::empty_array().raw());
   result.StorePointer(&result.raw_ptr()->exports_, Object::empty_array().raw());
+  result.StorePointer(&result.raw_ptr()->exports2_,
+      Object::empty_array().raw());
   result.StorePointer(&result.raw_ptr()->loaded_scripts_, Array::null());
   result.StorePointer(&result.raw_ptr()->load_error_, Instance::null());
   result.set_native_entry_resolver(NULL);
   result.set_native_entry_symbol_resolver(NULL);
   result.set_is_in_fullsnapshot(false);
   result.StoreNonPointer(&result.raw_ptr()->corelib_imported_, true);
   result.set_debuggable(false);
   result.set_is_dart_scheme(url.StartsWith(Symbols::DartScheme()));
   result.StoreNonPointer(&result.raw_ptr()->load_state_,
                          RawLibrary::kAllocated);
@@ skipping 11658 matching lines @@
   return UserTag::null();
 }
 
 
 const char* UserTag::ToCString() const {
   const String& tag_label = String::Handle(label());
   return tag_label.ToCString();
 }
 
 }  // namespace dart