Object ID Ring with tests

runtime/vm/scavenger.cc

 // Copyright (c) 2011, 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/scavenger.h"
 
 #include <algorithm>
 #include <map>
 #include <utility>
 
 #include "vm/dart.h"
 #include "vm/dart_api_state.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/stack_frame.h"
 #include "vm/store_buffer.h"
 #include "vm/verifier.h"
 #include "vm/visitor.h"
 #include "vm/weak_table.h"
+#include "vm/object_id_ring.h"
 
 namespace dart {
 
 // Scavenger uses RawObject::kMarkBit to distinguish forwaded and non-forwarded
 // objects. The kMarkBit does not intersect with the target address because of
 // object alignment.
 enum {
   kForwardingMask = 1 << RawObject::kMarkBit,
   kNotForwarded = 0,
   kForwarded = kForwardingMask,
@@ skipping 367 matching lines @@
     }
     delete pending;
     pending = next;
   }
   heap_->RecordData(kStoreBufferEntries, entries);
   // Done iterating through old objects remembered in the store buffers.
   visitor->VisitingOldObject(NULL);
 }
 
 
+void Scavenger::IterateObjectIdTable(Isolate* isolate,
+                                     ScavengerVisitor* visitor) {
+  ObjectIdRing* ring = isolate->object_id_ring();
+  ASSERT(ring != NULL);
+  ring->VisitPointers(visitor);
+}
+
+
 void Scavenger::IterateRoots(Isolate* isolate,
                              ScavengerVisitor* visitor,
                              bool visit_prologue_weak_persistent_handles) {
   int64_t start = OS::GetCurrentTimeMicros();
   isolate->VisitObjectPointers(visitor,
                                visit_prologue_weak_persistent_handles,
                                StackFrameIterator::kDontValidateFrames);
   int64_t middle = OS::GetCurrentTimeMicros();
   IterateStoreBuffers(isolate, visitor);
+  IterateObjectIdTable(isolate, visitor);
   int64_t end = OS::GetCurrentTimeMicros();
   heap_->RecordTime(kVisitIsolateRoots, middle - start);
   heap_->RecordTime(kIterateStoreBuffers, end - middle);
 }
 
 
 bool Scavenger::IsUnreachable(RawObject** p) {
   RawObject* raw_obj = *p;
   if (!raw_obj->IsHeapObject()) {
     return false;
@@ skipping 157 matching lines @@
         }
       }
     }
     // Remove the old table as it has been replaced with the newly allocated
     // table above.
     delete table;
   }
 }
 
 
+class ObjectIdRingMovePointerVisitor : public ObjectPointerVisitor {
+ public:
+  explicit ObjectIdRingMovePointerVisitor(Isolate* isolate) :
+      ObjectPointerVisitor(isolate) {}
+
+  void Move(RawObject** current) {
+    RawObject* raw_obj = *current;
+    ASSERT(raw_obj->IsHeapObject());
+    if (raw_obj->IsOldObject()) {
+      // Skip old objects.
+      return;
+    }
+    uword raw_addr = RawObject::ToAddr(raw_obj);
+    uword header = *reinterpret_cast<uword*>(raw_addr);
+    if (IsForwarding(header)) {
+      // The object has survived. Update its address in the table.
+      uword new_addr = ForwardedAddr(header);
+      raw_obj = RawObject::FromAddr(new_addr);
+      *current = raw_obj;
+    }
+  }
+
+  void VisitPointers(RawObject** first, RawObject** last) {
+    for (RawObject** current = first; current <= last; current++) {
+      Move(current);
+    }
+  }
+};
+
+
+void Scavenger::ProcessObjectIdTable(Isolate* isolate) {
+  ObjectIdRingMovePointerVisitor visitor(isolate);
+  ObjectIdRing* ring = isolate->object_id_ring();
+  ASSERT(ring != NULL);
+  ring->VisitPointers(&visitor);
+}
+
+
 void Scavenger::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
   uword cur = FirstObjectStart();
   while (cur < top_) {
     RawObject* raw_obj = RawObject::FromAddr(cur);
     cur += raw_obj->VisitPointers(visitor);
   }
 }
 
 
 void Scavenger::VisitObjects(ObjectVisitor* visitor) const {
@@ skipping 32 matching lines @@
   Prologue(isolate, invoke_api_callbacks);
   IterateRoots(isolate, &visitor, !invoke_api_callbacks);
   int64_t start = OS::GetCurrentTimeMicros();
   ProcessToSpace(&visitor);
   int64_t middle = OS::GetCurrentTimeMicros();
   IterateWeakReferences(isolate, &visitor);
   ScavengerWeakVisitor weak_visitor(this);
   IterateWeakRoots(isolate, &weak_visitor, invoke_api_callbacks);
   visitor.Finalize();
   ProcessWeakTables();
+  ProcessObjectIdTable(isolate);

[Ivan Posva, 2013/07/11 17:01:42]

It is unclear to me why you need this here and all the machinery associated with
it. You have already processed the object id ring above in IterateRoots.

[Cutch, 2013/07/11 21:31:47]

You are correct.

   int64_t end = OS::GetCurrentTimeMicros();
   heap_->RecordTime(kProcessToSpace, middle - start);
   heap_->RecordTime(kIterateWeaks, end - middle);
   Epilogue(isolate, invoke_api_callbacks);
 
   if (FLAG_verify_after_gc) {
     OS::PrintErr("Verifying after Scavenge...");
     heap_->Verify();
     OS::PrintErr(" done.\n");
   }
 
   // Done scavenging. Reset the marker.
   ASSERT(scavenging_);
   scavenging_ = false;
 }
 
 
 void Scavenger::WriteProtect(bool read_only) {
   space_->Protect(
       read_only ? VirtualMemory::kReadOnly : VirtualMemory::kReadWrite);
 }
 
 
 }  // namespace dart