1 files changed, 67 insertions, 0 deletions
diff --git a/java/com/android/dialer/app/contactinfo/ExpirableCacheHeadlessFragment.java b/java/com/android/dialer/app/contactinfo/ExpirableCacheHeadlessFragment.java
new file mode 100644
index 000000000..aed51b507
--- /dev/null
+++ b/java/com/android/dialer/app/contactinfo/ExpirableCacheHeadlessFragment.java
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2016 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.dialer.app.contactinfo;
+
+import android.os.Bundle;
+import android.support.annotation.NonNull;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
+import android.support.v7.app.AppCompatActivity;
+import com.android.dialer.phonenumbercache.ContactInfo;
+import com.android.dialer.util.ExpirableCache;
+
+/**
+ * Fragment without any UI whose purpose is to retain an instance of {@link ExpirableCache} across
+ * configuration change through the use of {@link #setRetainInstance(boolean)}. This is done as
+ * opposed to implementing {@link android.os.Parcelable} as it is a less widespread change.
+ */
+public class ExpirableCacheHeadlessFragment extends Fragment {
+
+  private static final String FRAGMENT_TAG = "ExpirableCacheHeadlessFragment";
+  private static final int CONTACT_INFO_CACHE_SIZE = 100;
+
+  private ExpirableCache<NumberWithCountryIso, ContactInfo> retainedCache;
+
+  @NonNull
+  public static ExpirableCacheHeadlessFragment attach(@NonNull AppCompatActivity parentActivity) {
+    return attach(parentActivity.getSupportFragmentManager());
+  }
+
+  @NonNull
+  private static ExpirableCacheHeadlessFragment attach(FragmentManager fragmentManager) {
+    ExpirableCacheHeadlessFragment fragment =
+        (ExpirableCacheHeadlessFragment) fragmentManager.findFragmentByTag(FRAGMENT_TAG);
+    if (fragment == null) {
+      fragment = new ExpirableCacheHeadlessFragment();
+      // Allowing state loss since in rare cases this is called after activity's state is saved and
+      // it's fine if the cache is lost.
+      fragmentManager.beginTransaction().add(fragment, FRAGMENT_TAG).commitNowAllowingStateLoss();
+    }
+    return fragment;
+  }
+
+  @Override
+  public void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    retainedCache = ExpirableCache.create(CONTACT_INFO_CACHE_SIZE);
+    setRetainInstance(true);
+  }
+
+  public ExpirableCache<NumberWithCountryIso, ContactInfo> getRetainedCache() {
+    return retainedCache;
+  }
+}