SettingsProvider: dup-suppress from cache.

On insert(), check to see if the value is redundant by checking if
it's the same value already in our cache (but without faulting it in
to check).  If so, avoid hitting sqlite or spamming all the
notification listeners with such uselessness.

This reportedly is happening a fair bit.

Change-Id: If58feb3ff1d00027dd927e0900087388cbcd72ae

1 files changed, 22 insertions, 1 deletions

diff --git a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
index 83937fa..1b4ba81 100644
--- a/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
+++ b/packages/SettingsProvider/src/com/android/providers/settings/SettingsProvider.java
@@ -436,11 +436,16 @@ public class SettingsProvider extends ContentProvider {
             if (!parseProviderList(url, initialValues)) return null;
         }
 
+        SettingsCache cache = SettingsCache.forTable(args.table);
+        String value = initialValues.getAsString(Settings.NameValueTable.VALUE);
+        if (SettingsCache.isRedundantSetValue(cache, name, value)) {
+            return Uri.withAppendedPath(url, name);
+        }
+
         SQLiteDatabase db = mOpenHelper.getWritableDatabase();
         final long rowId = db.insert(args.table, null, initialValues);
         if (rowId <= 0) return null;
 
-        SettingsCache cache = SettingsCache.forTable(args.table);
         SettingsCache.populate(cache, initialValues);  // before we notify
 
         if (LOCAL_LOGV) Log.v(TAG, args.table + " <- " + initialValues);
@@ -669,5 +674,21 @@ public class SettingsProvider extends ContentProvider {
             }
         }
 
+        /**
+         * For suppressing duplicate/redundant settings inserts early,
+         * checking our cache first (but without faulting it in),
+         * before going to sqlite with the mutation.
+         */
+        public static boolean isRedundantSetValue(SettingsCache cache, String name, String value) {
+            if (cache == null) return false;
+            synchronized (cache) {
+                Bundle bundle = cache.get(name);
+                if (bundle == null) return false;
+                String oldValue = bundle.getPairValue();
+                if (oldValue == null && value == null) return true;
+                if ((oldValue == null) != (value == null)) return false;
+                return oldValue.equals(value);
+            }
+        }
     }
 }