Remove hard limit from mirrors accessor caches.

sdk/lib/internal/lru.dart

-// Copyright (c) 2014, 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.
-
-part of dart._internal;
-
-class LRUAssociation<K,V> {
-  K key;
-  V value;
-  LRUAssociation previous;
-  LRUAssociation next;
-
-  void insertBetween(before, after) {
-    after.previous = this;
-    before.next = this;
-    this.next = after;
-    this.previous = before;
-  }
-
-  void remove() {
-    var after = next;
-    var before = previous;
-    after.previous = before;
-    before.next = after;
-  }
-}
-
-/**
- * A map with a fixed capacity that evicts associations when capacity is reached
- * on a least-recently-used basis. Implemented as an open addressing hash table
- * with doubly-linked entries forming the LRU queue.
- */
-class LRUMap<K,V> {
-  final LRUAssociation<K,V> _head;
-  final List _table;
-  final int _mask;
-  final int _capacity;  // Max number of associations before we start evicting.
-  int _size = 0;  // Current number of associations.
-
-  /**
-   * Create an LRUMap whose capacity is 75% of 2^shift.
-   */
-  LRUMap.withShift(int shift)
-      : this._mask = (1 << shift) - 1
-      , this._capacity = (1 << shift) * 3 ~/ 4
-      , this._table = new List(1 << shift)
-      , this._head = new LRUAssociation() {
-    // The scheme used here for handling collisions relies on there always
-    // being at least one empty slot.
-    if (shift < 1) throw new Exception("LRUMap requires a shift >= 1");
-    assert(_table.length > _capacity);
-    _head.insertBetween(_head, _head);
-  }
-
-  int _scanFor(K key) {
-    var start = key.hashCode & _mask;
-    var index = start;
-    do {
-      var assoc = _table[index];
-      if (null == assoc || assoc.key == key) {
-        return index;
-      }
-      index = (index + 1) & _mask;
-    } while (index != start);
-    // Should never happen because we start evicting associations before the
-    // table is full.
-    throw new Exception("Internal error: LRUMap table full");
-  }
-
-  void _fixCollisionsAfter(start) {
-    var assoc;
-    var index = (start + 1) & _mask;
-    while (null != (assoc = _table[index])) {
-      var newIndex = _scanFor(assoc.key);
-      if (newIndex != index) {
-        assert(_table[newIndex] == null);
-        _table[newIndex] = assoc;
-        _table[index] = null;
-      }
-      index = (index + 1) & _mask;
-    }
-  }
-
-  operator []=(K key, V value) {
-    int index = _scanFor(key);
-    var assoc = _table[index];
-    if (null != assoc) {
-      // Existing key, replace value.
-      assert(assoc.key == key);
-      assoc.value = value;
-      assoc.remove();
-      assoc.insertBetween(_head, _head.next);
-    } else {
-      // New key.
-      var newAssoc;
-      if (_size == _capacity) {
-        // Knock out the oldest association.
-        var lru = _head.previous;
-        lru.remove();
-        index = _scanFor(lru.key);
-        _table[index] = null;
-        _fixCollisionsAfter(index);
-        index = _scanFor(key);
-        newAssoc = lru;  // Recycle the association.
-      } else {
-        newAssoc = new LRUAssociation();
-        _size++;
-      }
-      newAssoc.key = key;
-      newAssoc.value = value;
-      newAssoc.insertBetween(_head, _head.next);
-      _table[index] = newAssoc;
-    }
-  }
-
-  V operator [](K key) {
-    var index = _scanFor(key);
-    var assoc = _table[index];
-    if (null == assoc) return null;
-    // Move to front of LRU queue.
-    assoc.remove();
-    assoc.insertBetween(_head, _head.next);
-    return assoc.value;
-  }
-}