diff --git a/cmds/installd/CacheTracker.h b/cmds/installd/CacheTracker.h
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+++ b/cmds/installd/CacheTracker.h
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+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_INSTALLD_CACHE_TRACKER_H
+#define ANDROID_INSTALLD_CACHE_TRACKER_H
+
+#include <memory>
+#include <string>
+#include <queue>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <android-base/macros.h>
+#include <cutils/multiuser.h>
+
+#include "CacheItem.h"
+
+namespace android {
+namespace installd {
+
+/**
+ * Cache tracker for a single UID. Each tracker is used in two modes: first
+ * for loading lightweight "stats", and then by loading detailed "items"
+ * which can then be purged to free up space.
+ */
+class CacheTracker {
+public:
+    CacheTracker(userid_t userId, appid_t appId, const std::string& quotaDevice);
+    ~CacheTracker();
+
+    std::string toString();
+
+    void addDataPath(const std::string& dataPath);
+
+    void loadStats();
+    void loadItems();
+
+    void ensureItems();
+
+    int getCacheRatio();
+
+    int64_t cacheUsed;
+    int64_t cacheQuota;
+
+    std::vector<std::shared_ptr<CacheItem>> items;
+
+private:
+    userid_t mUserId;
+    appid_t mAppId;
+    std::string mQuotaDevice;
+    bool mItemsLoaded;
+
+    std::vector<std::string> mDataPaths;
+
+    void loadItemsFrom(const std::string& path);
+
+    DISALLOW_COPY_AND_ASSIGN(CacheTracker);
+};
+
+}  // namespace installd
+}  // namespace android
+
+#endif  // ANDROID_INSTALLD_CACHE_TRACKER_H