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// Copyright (c) 2013, 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 "platform/globals.h"
#include "vm/tagged_pointer.h"
namespace dart {
// Forward declarations.
class ObjectPointerVisitor;
class JSONStream;
// A ring buffer of object pointers that have been given an id. An object
// may be pointed to by multiple ids. Objects contained in the ring will
// be preserved across scavenges but not old space collections.
// When the ring buffer wraps around older objects will be replaced and their
// ids will be invalidated.
class ObjectIdRing {
enum LookupResult {
kValid = 0,
kInvalid, // Malformed ring id (used in
kCollected, // Entry was reclaimed due to a full GC (entries are weak).
kExpired, // Entry was evicted during an insertion into a full ring.
enum IdPolicy {
kAllocateId, // Always allocate a new object id.
kReuseId, // If the object is already in the ring, reuse id.
// Otherwise allocate a new object id.
static const int32_t kMaxId = 0x3FFFFFFF;
static const int32_t kInvalidId = -1;
static const int32_t kDefaultCapacity = 8192;
// Adds the argument to the ring and returns its id. Note we do not allow
// adding Object::null().
int32_t GetIdForObject(ObjectPtr raw_obj, IdPolicy policy = kAllocateId);
// Returns Object::null() when the result is not kValid.
ObjectPtr GetObjectForId(int32_t id, LookupResult* kind);
void VisitPointers(ObjectPointerVisitor* visitor);
void PrintJSON(JSONStream* js);
friend class ObjectIdRingTestHelper;
void SetCapacityAndMaxSerial(int32_t capacity, int32_t max_serial);
int32_t FindExistingIdForObject(ObjectPtr raw_obj);
ObjectPtr* table_;
int32_t max_serial_;
int32_t capacity_;
int32_t serial_num_;
bool wrapped_;
ObjectPtr* table() { return table_; }
int32_t table_size() { return capacity_; }
int32_t NextSerial();
int32_t AllocateNewId(ObjectPtr object);
int32_t IndexOfId(int32_t id);
int32_t IdOfIndex(int32_t index);
bool IsValidContiguous(int32_t id);
bool IsValidId(int32_t id);
} // namespace dart