Add existing to tracked

node_modules/@cesium/engine/Source/Scene/Cesium3DTilesetCache.js

@@ -0,0 +1,80 @@
+import defined from "../Core/defined.js";
+import DoublyLinkedList from "../Core/DoublyLinkedList.js";
+
+/**
+ * Stores tiles with content loaded.
+ *
+ * @private
+ */
+function Cesium3DTilesetCache() {
+  // [head, sentinel) -> tiles that weren't selected this frame and may be removed from the cache
+  // (sentinel, tail] -> tiles that were selected this frame
+  this._list = new DoublyLinkedList();
+  this._sentinel = this._list.add();
+  this._trimTiles = false;
+}
+
+Cesium3DTilesetCache.prototype.reset = function () {
+  // Move sentinel node to the tail so, at the start of the frame, all tiles
+  // may be potentially replaced.  Tiles are moved to the right of the sentinel
+  // when they are selected so they will not be replaced.
+  this._list.splice(this._list.tail, this._sentinel);
+};
+
+Cesium3DTilesetCache.prototype.touch = function (tile) {
+  const node = tile.cacheNode;
+  if (defined(node)) {
+    this._list.splice(this._sentinel, node);
+  }
+};
+
+Cesium3DTilesetCache.prototype.add = function (tile) {
+  if (!defined(tile.cacheNode)) {
+    tile.cacheNode = this._list.add(tile);
+  }
+};
+
+Cesium3DTilesetCache.prototype.unloadTile = function (
+  tileset,
+  tile,
+  unloadCallback,
+) {
+  const node = tile.cacheNode;
+  if (!defined(node)) {
+    return;
+  }
+
+  this._list.remove(node);
+  tile.cacheNode = undefined;
+  unloadCallback(tileset, tile);
+};
+
+Cesium3DTilesetCache.prototype.unloadTiles = function (
+  tileset,
+  unloadCallback,
+) {
+  const trimTiles = this._trimTiles;
+  this._trimTiles = false;
+
+  const list = this._list;
+
+  // Traverse the list only to the sentinel since tiles/nodes to the
+  // right of the sentinel were used this frame.
+  //
+  // The sub-list to the left of the sentinel is ordered from LRU to MRU.
+  const sentinel = this._sentinel;
+  let node = list.head;
+  while (
+    node !== sentinel &&
+    (tileset.totalMemoryUsageInBytes > tileset.cacheBytes || trimTiles)
+  ) {
+    const tile = node.item;
+    node = node.next;
+    this.unloadTile(tileset, tile, unloadCallback);
+  }
+};
+
+Cesium3DTilesetCache.prototype.trim = function () {
+  this._trimTiles = true;
+};
+export default Cesium3DTilesetCache;