Improve the performance of displaying preference.

- Set a variable to record the status then replace getAvailabilityStatus() with it.

Test: manual test, use command to run MobileNetworkSettings and record it.
Bug: 154061428
Change-Id: Ia13a75a3821bb6c17d0dfeffb5043f47b60adf61

src/com/android/settings/network/telephony/TelephonyBasePreferenceController.java

@@ -23,12 +23,17 @@ import android.telephony.SubscriptionManager;
 
 import com.android.settings.core.BasePreferenceController;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+
 /**
  * {@link BasePreferenceController} that used by all preferences that requires subscription id.
  */
 public abstract class TelephonyBasePreferenceController extends BasePreferenceController
-        implements TelephonyAvailabilityCallback {
+        implements TelephonyAvailabilityCallback, TelephonyAvailabilityHandler {
     protected int mSubId;
+    private AtomicInteger mAvailabilityStatus = new AtomicInteger(0);
+    private AtomicBoolean mUnsetAvailabilityStatus = new AtomicBoolean(false);
 
     public TelephonyBasePreferenceController(Context context, String preferenceKey) {
         super(context, preferenceKey);
@@ -37,7 +42,21 @@ public abstract class TelephonyBasePreferenceController extends BasePreferenceCo
 
     @Override
     public int getAvailabilityStatus() {
-        return MobileNetworkUtils.getAvailability(mContext, mSubId, this::getAvailabilityStatus);
+        if (!mUnsetAvailabilityStatus.get()) {
+            mAvailabilityStatus.set(MobileNetworkUtils
+                    .getAvailability(mContext, mSubId, this::getAvailabilityStatus));
+        }
+        return mAvailabilityStatus.get();
+    }
+
+    @Override
+    public void setAvailabilityStatus(int status) {
+        mAvailabilityStatus.set(status);
+    }
+
+    @Override
+    public void unsetAvailabilityStatus(boolean enable) {
+        mUnsetAvailabilityStatus.set(enable);
     }
 
     /**