- Revert r24564 and r24563 due to unexplained malloc corruption.

runtime/vm/weak_table.h

-// 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.
-
-#ifndef VM_WEAK_TABLE_H_
-#define VM_WEAK_TABLE_H_
-
-#include "vm/globals.h"
-
-#include "platform/assert.h"
-#include "vm/raw_object.h"
-
-namespace dart {
-
-class WeakTable {
- public:
-  explicit WeakTable(intptr_t size) : used_(0), count_(0) {
-    ASSERT(size >= 0);
-    if (size < kMinSize) {
-      size = kMinSize;
-    }
-    data_ = reinterpret_cast<intptr_t*>(calloc(size, kEntrySize * kWordSize));
-    size_ = size;
-  }
-
-  static WeakTable* NewFrom(WeakTable* original) {
-    intptr_t cnt = original->count();
-    intptr_t sz = original->size();
-    intptr_t new_sz = sz;
-
-    if (cnt <= (sz / 4)) {
-      // Reduce the capacity.
-      new_sz = sz / 2;
-    } else if (cnt > (sz / 2)) {
-      // Increase the capacity.
-      new_sz = sz * 2;
-      if (new_sz < sz) {
-        FATAL("Reached impossible state of having more weak table entries"
-              " than memory available for heap objects.");
-      }
-    }
-    return new WeakTable(new_sz);
-  }
-
-  intptr_t size() const { return size_; }
-  intptr_t used() const { return used_; }
-  intptr_t count() const { return count_; }
-
-  bool IsValidEntryAt(intptr_t i) const {
-    ASSERT(((ValueAt(i) == 0) &&
-            ((ObjectAt(i) == NULL) ||
-             (data_[ObjectIndex(i)] == kDeletedEntry))) ||
-           ((ValueAt(i) != 0) &&
-            (ObjectAt(i) != NULL) &&
-            (data_[ObjectIndex(i)] != kDeletedEntry)));
-    return (data_[ValueIndex(i)] != 0);
-  }
-
-  void InvalidateAt(intptr_t i) {
-    ASSERT(IsValidEntryAt(i));
-    SetValueAt(i, 0);
-  }
-
-  RawObject* ObjectAt(intptr_t i) const {
-    return reinterpret_cast<RawObject*>(data_[ObjectIndex(i)]);
-  }
-
-  intptr_t ValueAt(intptr_t i) const {
-    return data_[ValueIndex(i)];
-  }
-
-  WeakTable* SetValue(RawObject* key, intptr_t val);
-
-  intptr_t GetValue(RawObject* key) const {
-    intptr_t sz = size();
-    intptr_t idx = Hash(key) % sz;
-    RawObject* obj = ObjectAt(idx);
-    while (obj != NULL) {
-      if (obj == key) {
-        return ValueAt(idx);
-      }
-      idx = (idx + 1) % sz;
-      obj = ObjectAt(idx);
-    }
-    ASSERT(ValueAt(idx) == 0);
-    return 0;
-  }
-
- private:
-  enum {
-    kObjectOffset = 0,
-    kValueOffset,
-    kEntrySize,
-  };
-
-  static const intptr_t kDeletedEntry = 1;  // Equivalent to a tagged NULL.
-  static const intptr_t kMinSize = 8;
-
-  static intptr_t LimitFor(intptr_t size) {
-    // Maintain a maximum of 75% fill rate.
-    return 3 * (size / 4);
-  }
-  intptr_t limit() const { return LimitFor(size()); }
-
-  intptr_t index(intptr_t i) const {
-    ASSERT(i >= 0);
-    ASSERT(i < size());
-    return i * kEntrySize;
-  }
-
-  void set_used(intptr_t val) {
-    ASSERT(val <= limit());
-    used_ = val;
-  }
-
-  void set_count(intptr_t val) {
-    ASSERT(val <= limit());
-    ASSERT(val <= used());
-    count_ = val;
-  }
-
-  intptr_t ObjectIndex(intptr_t i) const {
-    return index(i) + kObjectOffset;
-  }
-
-  intptr_t ValueIndex(intptr_t i) const {
-    return index(i) + kValueOffset;
-  }
-
-  void SetObjectAt(intptr_t i, RawObject* key) {
-    data_[ObjectIndex(i)] = reinterpret_cast<intptr_t>(key);
-  }
-
-  void SetValueAt(intptr_t i, intptr_t val) {
-    // Setting a value of 0 is equivalent to invalidating the entry.
-    if (val == 0) {
-      data_[ObjectIndex(i)] = kDeletedEntry;
-      set_count(count() - 1);
-    }
-    data_[ValueIndex(i)] = val;
-  }
-
-  WeakTable* Rehash();
-
-  static intptr_t Hash(RawObject* key) {
-    return reinterpret_cast<intptr_t>(key) >> kObjectAlignmentLog2;
-  }
-
-  // data_ contains size_ tuples of key/value.
-  intptr_t* data_;
-  // size_ keeps the number of entries in data_. used_ maintains the number of
-  // non-NULL entries and will trigger rehashing if needed. count_ stores the
-  // number valid entries, and will determine the size_ after rehashing.
-  intptr_t size_;
-  intptr_t used_;
-  intptr_t count_;
-
-  DISALLOW_IMPLICIT_CONSTRUCTORS(WeakTable);
-};
-
-}  // namespace dart
-
-#endif  // VM_WEAK_TABLE_H_