From eafb535072698b0559d8919db4b18618359c11b9 Mon Sep 17 00:00:00 2001
From: Christopher Tate <ctate@google.com>
Date: Tue, 4 Oct 2016 16:34:48 -0700
Subject: [PATCH] Eliminate unnecessary object churn in job scheduler updating

The arbitrary-caller "what job is currently running?" state inspector
returns a clone of the JobStatus record for it, not a live reference
to the scheduler's active state.  That's appropriate for most cases
but when doing its own internal bookkeeping, the object churn in cloning
(especially, an unneeded clone just for purposes of comparing to some
other job!) is merely a huge waste of CPU and GC load.

So now we don't do that unnecessarily, and everything is much leaner.

Bug 31751985

Change-Id: Idacb52e9e5ca17b9e12b7ccd2fc2e1ec8b3547f6
---
 .../core/java/com/android/server/job/JobSchedulerService.java    | 6 +++++-
 services/core/java/com/android/server/job/JobServiceContext.java | 9 +++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/services/core/java/com/android/server/job/JobSchedulerService.java b/services/core/java/com/android/server/job/JobSchedulerService.java
index 9d931467d914..ba3977268190 100644
--- a/services/core/java/com/android/server/job/JobSchedulerService.java
+++ b/services/core/java/com/android/server/job/JobSchedulerService.java
@@ -907,7 +907,11 @@ public final class JobSchedulerService extends com.android.server.SystemService
     private boolean isCurrentlyActiveLocked(JobStatus job) {
         for (int i=0; i<mActiveServices.size(); i++) {
             JobServiceContext serviceContext = mActiveServices.get(i);
-            final JobStatus running = serviceContext.getRunningJob();
+            // The 'unsafe' direct-internal-reference running-job inspector is okay to
+            // use here because we are already holding the necessary lock *and* we
+            // immediately discard the returned object reference, if any; we return
+            // only a boolean state indicator to the caller.
+            final JobStatus running = serviceContext.getRunningJobUnsafeLocked();
             if (running != null && running.matches(job.getUid(), job.getJobId())) {
                 return true;
             }
diff --git a/services/core/java/com/android/server/job/JobServiceContext.java b/services/core/java/com/android/server/job/JobServiceContext.java
index 5989c3897c82..5e495fab3f6e 100644
--- a/services/core/java/com/android/server/job/JobServiceContext.java
+++ b/services/core/java/com/android/server/job/JobServiceContext.java
@@ -230,6 +230,15 @@ public class JobServiceContext extends IJobCallback.Stub implements ServiceConne
         return job == null ? null : new JobStatus(job);
     }
 
+    /**
+     * Internal non-cloning inspection of the currently running job, if any.  The lock
+     * must be held when calling this *and* for the entire lifetime of using its returned
+     * JobStatus object!
+     */
+    JobStatus getRunningJobUnsafeLocked() {
+        return mRunningJob;
+    }
+
     /** Called externally when a job that was scheduled for execution should be cancelled. */
     void cancelExecutingJob(int reason) {
         mCallbackHandler.obtainMessage(MSG_CANCEL, reason, 0 /* unused */).sendToTarget();
-- 
2.11.0