Attempt no. 3 to fix Heap::IsHeapIterable and HeapIterator

src/runtime.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 #include <limits>
 
 #include "v8.h"
 
 #include "accessors.h"
@@ skipping 13097 matching lines @@
 
 
 // Scan the heap for objects with direct references to an object
 // args[0]: the object to find references to
 // args[1]: constructor function for instances to exclude (Mirror)
 // args[2]: the the maximum number of objects to return
 RUNTIME_FUNCTION(Runtime_DebugReferencedBy) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 3);
 
-  // First perform a full GC in order to avoid references from dead objects.
-  Heap* heap = isolate->heap();
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugReferencedBy");
-  // The heap iterator reserves the right to do a GC to make the heap iterable.
-  // Due to the GC above we know it won't need to do that, but it seems cleaner
-  // to get the heap iterator constructed before we start having unprotected
-  // Object* locals that are not protected by handles.
-
   // Check parameters.
   CONVERT_ARG_HANDLE_CHECKED(JSObject, target, 0);
   CONVERT_ARG_HANDLE_CHECKED(Object, instance_filter, 1);
   RUNTIME_ASSERT(instance_filter->IsUndefined() ||
                  instance_filter->IsJSObject());
   CONVERT_NUMBER_CHECKED(int32_t, max_references, Int32, args[2]);
   RUNTIME_ASSERT(max_references >= 0);
 
 
   // Get the constructor function for context extension and arguments array.
   Handle<JSObject> arguments_boilerplate(
       isolate->context()->native_context()->sloppy_arguments_boilerplate());
   Handle<JSFunction> arguments_function(
       JSFunction::cast(arguments_boilerplate->map()->constructor()));
 
   // Get the number of referencing objects.
   int count;
-  HeapIterator heap_iterator(heap);
-  count = DebugReferencedBy(&heap_iterator,
-                            *target, *instance_filter, max_references,
-                            NULL, 0, *arguments_function);
+  // First perform a full GC in order to avoid dead objects and to make the heap
+  // iterable.
+  Heap* heap = isolate->heap();
+  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");
+  {
+    HeapIterator heap_iterator(heap);
+    count = DebugReferencedBy(&heap_iterator,
+                              *target, *instance_filter, max_references,
+                              NULL, 0, *arguments_function);
+  }
 
   // Allocate an array to hold the result.
   Handle<FixedArray> instances = isolate->factory()->NewFixedArray(count);
 
   // Fill the referencing objects.
-  // AllocateFixedArray above does not make the heap non-iterable.
-  ASSERT(heap->IsHeapIterable());
-  HeapIterator heap_iterator2(heap);
-  count = DebugReferencedBy(&heap_iterator2,
-                            *target, *instance_filter, max_references,
-                            *instances, count, *arguments_function);
+  {
+    HeapIterator heap_iterator(heap);
+    count = DebugReferencedBy(&heap_iterator,
+                              *target, *instance_filter, max_references,
+                              *instances, count, *arguments_function);
+  }
 
   // Return result as JS array.
   Handle<JSFunction> constructor(
       isolate->context()->native_context()->array_function());
 
   Handle<JSObject> result = isolate->factory()->NewJSObject(constructor);
   JSArray::SetContent(Handle<JSArray>::cast(result), instances);
   return *result;
 }
 
@@ skipping 30 matching lines @@
 }
 
 
 // Scan the heap for objects constructed by a specific function.
 // args[0]: the constructor to find instances of
 // args[1]: the the maximum number of objects to return
 RUNTIME_FUNCTION(Runtime_DebugConstructedBy) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);
 
-  // First perform a full GC in order to avoid dead objects.
-  Heap* heap = isolate->heap();
-  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");
 
   // Check parameters.
   CONVERT_ARG_HANDLE_CHECKED(JSFunction, constructor, 0);
   CONVERT_NUMBER_CHECKED(int32_t, max_references, Int32, args[1]);
   RUNTIME_ASSERT(max_references >= 0);
 
   // Get the number of referencing objects.
   int count;
-  HeapIterator heap_iterator(heap);
-  count = DebugConstructedBy(&heap_iterator,
-                             *constructor,
-                             max_references,
-                             NULL,
-                             0);
+  // First perform a full GC in order to avoid dead objects and to make the heap
+  // iterable.
+  Heap* heap = isolate->heap();
+  heap->CollectAllGarbage(Heap::kMakeHeapIterableMask, "%DebugConstructedBy");
+  {
+    HeapIterator heap_iterator(heap);
+    count = DebugConstructedBy(&heap_iterator,
+                               *constructor,
+                               max_references,
+                               NULL,
+                               0);
+  }
 
   // Allocate an array to hold the result.
   Handle<FixedArray> instances = isolate->factory()->NewFixedArray(count);
 
-  ASSERT(heap->IsHeapIterable());
   // Fill the referencing objects.
-  HeapIterator heap_iterator2(heap);
-  count = DebugConstructedBy(&heap_iterator2,
-                             *constructor,
-                             max_references,
-                             *instances,
-                             count);
+  {
+    HeapIterator heap_iterator2(heap);
+    count = DebugConstructedBy(&heap_iterator2,
+                               *constructor,
+                               max_references,
+                               *instances,
+                               count);
+  }
 
   // Return result as JS array.
   Handle<JSFunction> array_function(
       isolate->context()->native_context()->array_function());
   Handle<JSObject> result = isolate->factory()->NewJSObject(array_function);
   JSArray::SetContent(Handle<JSArray>::cast(result), instances);
   return *result;
 }
 
 
@@ skipping 111 matching lines @@
   RUNTIME_ASSERT(script_value->value()->IsScript());
   Handle<Script> script = Handle<Script>(Script::cast(script_value->value()));
 
   const int kBufferSize = 32;
 
   Handle<FixedArray> array;
   array = isolate->factory()->NewFixedArray(kBufferSize);
   int number;
   Heap* heap = isolate->heap();
   {
-    heap->EnsureHeapIsIterable();
-    DisallowHeapAllocation no_allocation;
     HeapIterator heap_iterator(heap);
     Script* scr = *script;
     FixedArray* arr = *array;
     number = FindSharedFunctionInfosForScript(&heap_iterator, scr, arr);
   }
   if (number > kBufferSize) {
     array = isolate->factory()->NewFixedArray(number);
-    heap->EnsureHeapIsIterable();
-    DisallowHeapAllocation no_allocation;
     HeapIterator heap_iterator(heap);
     Script* scr = *script;
     FixedArray* arr = *array;
     FindSharedFunctionInfosForScript(&heap_iterator, scr, arr);
   }
 
   Handle<JSArray> result = isolate->factory()->NewJSArrayWithElements(array);
   result->set_length(Smi::FromInt(number));
 
   LiveEdit::WrapSharedFunctionInfos(result);
@@ skipping 1062 matching lines @@
 // traversals might be required rendering this operation as a rather slow
 // operation. However for setting break points which is normally done through
 // some kind of user interaction the performance is not crucial.
 static Handle<Object> Runtime_GetScriptFromScriptName(
     Handle<String> script_name) {
   // Scan the heap for Script objects to find the script with the requested
   // script data.
   Handle<Script> script;
   Factory* factory = script_name->GetIsolate()->factory();
   Heap* heap = script_name->GetHeap();
-  heap->EnsureHeapIsIterable();
-  DisallowHeapAllocation no_allocation_during_heap_iteration;
   HeapIterator iterator(heap);
   HeapObject* obj = NULL;
   while (script.is_null() && ((obj = iterator.next()) != NULL)) {
     // If a script is found check if it has the script data requested.
     if (obj->IsScript()) {
       if (Script::cast(obj)->name()->IsString()) {
         if (String::cast(Script::cast(obj)->name())->Equals(*script_name)) {
           script = Handle<Script>(Script::cast(obj));
         }
       }
@@ skipping 736 matching lines @@
   }
   return NULL;
 }
 
 
 const Runtime::Function* Runtime::FunctionForId(Runtime::FunctionId id) {
   return &(kIntrinsicFunctions[static_cast<int>(id)]);
 }
 
 } }  // namespace v8::internal