Lazy peer API.

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"
@@ skipping 487 matching lines @@
     // Key is white.  Delay the weak property.
     visitor->DelayWeakProperty(raw_weak);
     return raw_weak->Size();
   } else {
     // Key is gray or black.  Make the weak property black.
     return raw_weak->VisitPointers(visitor);
   }
 }
 
 
+void Scavenger::ProcessPeerReferents() {
+  PeerTable prev;
+  std::swap(prev, peer_table_);
+  for (PeerTable::iterator it = prev.begin(); it != prev.end(); ++it) {
+    RawObject* raw_obj = it->first;
+    ASSERT(raw_obj->IsHeapObject());
+    uword raw_addr = RawObject::ToAddr(raw_obj);
+    uword header = *reinterpret_cast<uword*>(raw_addr);
+    if (IsForwarding(header)) {
+      // The object has survived.  Preserve its record.
+      uword new_addr = ForwardedAddr(header);
+      raw_obj = RawObject::FromAddr(new_addr);
+      heap_->SetPeer(raw_obj, it->second);
+    }
+  }
+}
+
+
 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 34 matching lines @@
   timer.Start();
   // Setup the visitor and run a scavenge.
   ScavengerVisitor visitor(isolate, this);
   Prologue(isolate, invoke_api_callbacks);
   IterateRoots(isolate, &visitor, !invoke_api_callbacks);
   ProcessToSpace(&visitor);
   IterateWeakReferences(isolate, &visitor);
   ScavengerWeakVisitor weak_visitor(this);
   IterateWeakRoots(isolate, &weak_visitor, invoke_api_callbacks);
   visitor.Finalize();
+  ProcessPeerReferents();
   Epilogue(isolate, invoke_api_callbacks);
   timer.Stop();
   if (FLAG_verbose_gc) {
     OS::PrintErr("Scavenge[%d]: %"Pd64"us\n",
                  count_,
                  timer.TotalElapsedTime());
   }
 
   if (FLAG_verify_after_gc) {
     OS::PrintErr("Verifying after Scavenge...");
     heap_->Verify();
     OS::PrintErr(" done.\n");
   }
 
   count_++;
   // Done scavenging. Reset the marker.
   ASSERT(scavenging_);
   scavenging_ = false;
 }
 
 
 void Scavenger::WriteProtect(bool read_only) {
   space_->Protect(
       read_only ? VirtualMemory::kReadOnly : VirtualMemory::kReadWrite);
 }
 
+
+void Scavenger::SetPeer(RawObject* raw_obj, void* peer) {
+  if (peer == NULL) {
+    peer_table_.erase(raw_obj);
+  } else {
+    peer_table_[raw_obj] = peer;
+  }
+}
+
+
+void* Scavenger::GetPeer(RawObject* raw_obj) {
+  PeerTable::iterator it = peer_table_.find(raw_obj);
+  return (it == peer_table_.end()) ? NULL : it->second;
+}
+
+
+int64_t Scavenger::PeerCount() const {
+  return static_cast<int64_t>(peer_table_.size());
+}
+
 }  // namespace dart