Adding an asynchronous search interface for apps search

Change-Id: Ib09df0a3d587dc60ed888ddbd0edf058e4a1cc3e

src/com/android/launcher3/model/AbstractUserComparator.java

@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+package com.android.launcher3.model;
+
+import android.content.Context;
+
+import com.android.launcher3.ItemInfo;
+import com.android.launcher3.compat.UserHandleCompat;
+import com.android.launcher3.compat.UserManagerCompat;
+
+import java.util.Comparator;
+import java.util.HashMap;
+
+/**
+ * A comparator to arrange items based on user profiles.
+ */
+public abstract class AbstractUserComparator<T extends ItemInfo> implements Comparator<T> {
+
+    private HashMap<UserHandleCompat, Long> mUserSerialCache = new HashMap<>();
+    private final UserManagerCompat mUserManager;
+    private final UserHandleCompat mMyUser;
+
+    public AbstractUserComparator(Context context) {
+        mUserManager = UserManagerCompat.getInstance(context);
+        mMyUser = UserHandleCompat.myUserHandle();
+    }
+
+    @Override
+    public int compare(T lhs, T rhs) {
+        if (mMyUser.equals(lhs.user)) {
+            return -1;
+        } else {
+            Long aUserSerial = getAndCacheUserSerial(lhs.user);
+            Long bUserSerial = getAndCacheUserSerial(rhs.user);
+            return aUserSerial.compareTo(bUserSerial);
+        }
+    }
+
+    /**
+     * Returns the user serial for this user, using a cached serial if possible.
+     */
+    private Long getAndCacheUserSerial(UserHandleCompat user) {
+        Long userSerial = mUserSerialCache.get(user);
+        if (userSerial == null) {
+            userSerial = mUserManager.getSerialNumberForUser(user);
+            mUserSerialCache.put(user, userSerial);
+        }
+        return userSerial;
+    }
+
+    public void clearUserCache() {
+        mUserSerialCache.clear();
+    }
+}