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

runtime/vm/parser.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/parser.h"
 #include "vm/flags.h"
 
 #ifndef DART_PRECOMPILED_RUNTIME
 
 #include "lib/invocation_mirror.h"
@@ skipping 473 matching lines @@
 }
 
 
 void Parser::SetPosition(TokenPosition position) {
   tokens_iterator_.SetCurrentPosition(position);
   token_kind_ = Token::kILLEGAL;
   prev_token_pos_ = position;
 }
 
 
+// Set state and increments generational count so that thge background compiler
+// can detect if loading/top-level-parsing occured during compilation.
+class TopLevelParsingScope : public ValueObject {
+ public:
+  explicit TopLevelParsingScope(Isolate* isolate) : isolate_(isolate) {
+    isolate_->set_top_level_parsing(true);
+    isolate_->IncrLoadingInvalidationGen();
+  }
+  ~TopLevelParsingScope() {
+    isolate_->set_top_level_parsing(false);
+    isolate_->IncrLoadingInvalidationGen();
+  }

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

Both constructor and destructor are incrementing the loading_invalidation_gen_
value, is that needed? Do you want to differentiate between start of top level
parsing and end?

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

I do not need to differentiate. The only information I need is that the a
loading occurred. In that context, I only need to increment the loading counter
at the exit, since the start and loading is covered by the IsTopLevelParsing
state/check. 

+
+ private:
+  Isolate* isolate_;
+};
+
+
 void Parser::ParseCompilationUnit(const Library& library,
                                   const Script& script) {
   Thread* thread = Thread::Current();
   ASSERT(thread->long_jump_base()->IsSafeToJump());
   CSTAT_TIMER_SCOPE(thread, parser_timer);
   VMTagScope tagScope(thread, VMTag::kCompileTopLevelTagId);
 #ifndef PRODUCT
   TimelineDurationScope tds(thread,
                             Timeline::GetCompilerStream(),
                             "CompileTopLevel");
   if (tds.enabled()) {
     tds.SetNumArguments(1);
     tds.CopyArgument(0, "script", String::Handle(script.url()).ToCString());
   }
 #endif
 
+  TopLevelParsingScope scope(thread->isolate());
   Parser parser(script, library, TokenPosition::kMinSource);
   parser.ParseTopLevel();
 }
 
 
 void Parser::ComputeCurrentToken() {
   ASSERT(token_kind_ == Token::kILLEGAL);
   token_kind_ = tokens_iterator_.CurrentTokenKind();
   if (token_kind_ == Token::kERROR) {
     ReportError(TokenPos(), "%s", CurrentLiteral()->ToCString());
@@ skipping 13927 matching lines @@
     const ArgumentListNode& function_args,
     const LocalVariable* temp_for_last_arg,
     bool is_super_invocation) {
   UNREACHABLE();
   return NULL;
 }
 
 }  // namespace dart
 
 #endif  // DART_PRECOMPILED_RUNTIME