Fake the cache size to be 0 bytes when cleared.

The fast track storage calculation returns a non-zero answer after
the storage has been cleared. The simplest workaround here is to
fake the size as 0 bytes in the view after cache clearing.

It will not be zero if the user exits and comes back, but this
should be fine.

MARK IT ZERO!

Change-Id: Ia012c2cf2842040d5eac3d4a72539ec7dcfb9570
Fixes: 34965659
Test: Settings Robotest
(cherry picked from commit bf1f8e9ca7)

src/com/android/settings/applications/AppStorageSettings.java

@@ -101,6 +101,8 @@ public class AppStorageSettings extends AppInfoWithHeader
     private static final String KEY_URI_CATEGORY = "uri_category";
     private static final String KEY_CLEAR_URI = "clear_uri_button";
 
+    private static final String KEY_CACHE_CLEARED = "cache_cleared";
+
     // Views related to cache info
     private Preference mCacheSize;
     private Button mClearDataButton;
@@ -115,6 +117,7 @@ public class AppStorageSettings extends AppInfoWithHeader
     private PreferenceCategory mUri;
 
     private boolean mCanClearData = true;
+    private boolean mCacheCleared;
 
     private AppStorageStats mLastResult;
     private AppStorageSizesController mSizeController;
@@ -133,6 +136,9 @@ public class AppStorageSettings extends AppInfoWithHeader
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
+        if (savedInstanceState != null) {
+            mCacheCleared = savedInstanceState.getBoolean(KEY_CACHE_CLEARED, false);
+        }
 
         addPreferencesFromResource(R.xml.app_storage_settings);
         setupViews();
@@ -145,6 +151,12 @@ public class AppStorageSettings extends AppInfoWithHeader
         updateSize();
     }
 
+    @Override
+    public void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        outState.putBoolean(KEY_CACHE_CLEARED, mCacheCleared);
+    }
+
     private void setupViews() {
         mComputingStr = getActivity().getText(R.string.computing_size);
         mInvalidSizeStr = getActivity().getText(R.string.invalid_size_value);
@@ -523,6 +535,10 @@ public class AppStorageSettings extends AppInfoWithHeader
     }
 
     private void updateUiWithSize(AppStorageStats result) {
+        if (mCacheCleared) {
+            mSizeController.setCacheCleared(true);
+        }
+
         mSizeController.updateUi(getContext());
 
         if (result == null) {
@@ -539,7 +555,7 @@ public class AppStorageSettings extends AppInfoWithHeader
                 mClearDataButton.setEnabled(true);
                 mClearDataButton.setOnClickListener(this);
             }
-            if (cacheSize <= 0) {
+            if (cacheSize <= 0 || mCacheCleared) {
                 mClearCacheButton.setEnabled(false);
             } else {
                 mClearCacheButton.setEnabled(true);
@@ -562,6 +578,7 @@ public class AppStorageSettings extends AppInfoWithHeader
                     processClearMsg(msg);
                     break;
                 case MSG_CLEAR_CACHE:
+                    mCacheCleared = true;
                     // Refresh size info
                     updateSize();
                     break;

src/com/android/settings/applications/AppStorageSizesController.java

@@ -39,6 +39,7 @@ public class AppStorageSizesController {
     @Nullable
     private StorageStatsSource.AppStorageStats mLastResult;
     private boolean mLastResultFailed;
+    private boolean mCachedCleared;
     private long mLastCodeSize = -1;
     private long mLastDataSize = -1;
     private long mLastCacheSize = -1;
@@ -77,7 +78,7 @@ public class AppStorageSizesController {
                 mLastDataSize = dataSize;
                 mDataSize.setSummary(getSizeStr(context, dataSize));
             }
-            long cacheSize = mLastResult.getCacheBytes();
+            long cacheSize = mCachedCleared ? 0 : mLastResult.getCacheBytes();
             if (mLastCacheSize != cacheSize) {
                 mLastCacheSize = cacheSize;
                 mCacheSize.setSummary(getSizeStr(context, cacheSize));
@@ -100,6 +101,15 @@ public class AppStorageSizesController {
         mLastResultFailed = result == null;
     }
 
+    /**
+     * Sets if we have cleared the cache and should zero the cache bytes.
+     * When the cache is cleared, the cache directories are recreated. These directories have
+     * some size, but are empty. We zero this out to best match user expectations.
+     */
+    public void setCacheCleared(boolean isCleared) {
+        mCachedCleared = isCleared;
+    }
+
     private String getSizeStr(Context context, long size) {
         return Formatter.formatFileSize(context, size);
     }

tests/robotests/src/com/android/settings/applications/AppStorageSizesControllerTest.java

@@ -92,4 +92,22 @@ public class AppStorageSizesControllerTest {
         assertThat(mDataPreference.getSummary()).isEqualTo("100B");
         assertThat(mTotalPreference.getSummary()).isEqualTo("111B");
     }
+
+    @Test
+    public void fakeCacheFlagSetsCacheToZero() {
+        AppStorageStats result = mock(AppStorageStats.class);
+        when(result.getCodeBytes()).thenReturn(1L);
+        when(result.getCacheBytes()).thenReturn(10L);
+        when(result.getDataBytes()).thenReturn(100L);
+        when(result.getTotalBytes()).thenReturn(111L);
+
+        mController.setResult(result);
+        mController.setCacheCleared(true);
+        mController.updateUi(mContext);
+
+        assertThat(mAppPreference.getSummary()).isEqualTo("1.00B");
+        assertThat(mCachePreference.getSummary()).isEqualTo("0.00B");
+        assertThat(mDataPreference.getSummary()).isEqualTo("100B");
+        assertThat(mTotalPreference.getSummary()).isEqualTo("101B");
+    }
 }