From 7cbad8a06348574ae1f3ed3d7950309e5de90f7a Mon Sep 17 00:00:00 2001
From: Sudheer Shanka <sudheersai@google.com>
Date: Fri, 11 Feb 2022 15:44:38 -0800
Subject: [PATCH] Cache IAlarmManager binder handle.

Bug: 218909495
Test: treehugger
Change-Id: Ib73dac85999311993fa9f0d552609065c24a155c
---
 core/java/android/os/SystemClock.java | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/core/java/android/os/SystemClock.java b/core/java/android/os/SystemClock.java
index b9252d6438109..7379443877b70 100644
--- a/core/java/android/os/SystemClock.java
+++ b/core/java/android/os/SystemClock.java
@@ -104,6 +104,8 @@ import java.time.ZoneOffset;
 public final class SystemClock {
     private static final String TAG = "SystemClock";
 
+    private static volatile IAlarmManager sIAlarmManager;
+
     /**
      * This class is uninstantiable.
      */
@@ -151,8 +153,7 @@ public final class SystemClock {
      * @return if the clock was successfully set to the specified time.
      */
     public static boolean setCurrentTimeMillis(long millis) {
-        final IAlarmManager mgr = IAlarmManager.Stub
-                .asInterface(ServiceManager.getService(Context.ALARM_SERVICE));
+        final IAlarmManager mgr = getIAlarmManager();
         if (mgr == null) {
             Slog.e(TAG, "Unable to set RTC: mgr == null");
             return false;
@@ -280,8 +281,7 @@ public final class SystemClock {
      * @hide
      */
     public static long currentNetworkTimeMillis() {
-        final IAlarmManager mgr = IAlarmManager.Stub
-                .asInterface(ServiceManager.getService(Context.ALARM_SERVICE));
+        final IAlarmManager mgr = getIAlarmManager();
         if (mgr != null) {
             try {
                 return mgr.currentNetworkTimeMillis();
@@ -296,6 +296,14 @@ public final class SystemClock {
         }
     }
 
+    private static IAlarmManager getIAlarmManager() {
+        if (sIAlarmManager == null) {
+            sIAlarmManager = IAlarmManager.Stub
+                    .asInterface(ServiceManager.getService(Context.ALARM_SERVICE));
+        }
+        return sIAlarmManager;
+    }
+
     /**
      * Returns a {@link Clock} that starts at January 1, 1970 00:00:00.0 UTC,
      * synchronized using a remote network source outside the device.