From 57affbf91d016eda1395106c4d5f0350471dca85 Mon Sep 17 00:00:00 2001
From: Rick Yiu <rickyiu@google.com>
Date: Tue, 11 Feb 2020 14:59:37 +0800
Subject: [PATCH] Add choice for changing sched policy when setting thread
 priority

If the policy has been changed already, we do not need to change
it again.

Bug: 139521784
Test: functionality verified
Change-Id: I251db1d3f874896ba9be68df87209e7e514b80f9
---
 libutils/Threads.cpp                    | 25 +++++++++++++------------
 libutils/include/utils/AndroidThreads.h |  4 +++-
 2 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/libutils/Threads.cpp b/libutils/Threads.cpp
index 540dcf49d..147db542d 100644
--- a/libutils/Threads.cpp
+++ b/libutils/Threads.cpp
@@ -302,8 +302,7 @@ void androidSetCreateThreadFunc(android_create_thread_fn func)
 }
 
 #if defined(__ANDROID__)
-int androidSetThreadPriority(pid_t tid, int pri)
-{
+int androidSetThreadPriority(pid_t tid, int pri, bool change_policy) {
     int rc = 0;
     int lasterr = 0;
     int curr_pri = getpriority(PRIO_PROCESS, tid);
@@ -312,17 +311,19 @@ int androidSetThreadPriority(pid_t tid, int pri)
         return rc;
     }
 
-    if (pri >= ANDROID_PRIORITY_BACKGROUND) {
-        rc = SetTaskProfiles(tid, {"SCHED_SP_BACKGROUND"}, true) ? 0 : -1;
-    } else if (curr_pri >= ANDROID_PRIORITY_BACKGROUND) {
-        SchedPolicy policy = SP_FOREGROUND;
-        // Change to the sched policy group of the process.
-        get_sched_policy(getpid(), &policy);
-        rc = SetTaskProfiles(tid, {get_sched_policy_profile_name(policy)}, true) ? 0 : -1;
-    }
+    if (change_policy) {
+        if (pri >= ANDROID_PRIORITY_BACKGROUND) {
+            rc = SetTaskProfiles(tid, {"SCHED_SP_BACKGROUND"}, true) ? 0 : -1;
+        } else if (curr_pri >= ANDROID_PRIORITY_BACKGROUND) {
+            SchedPolicy policy = SP_FOREGROUND;
+            // Change to the sched policy group of the process.
+            get_sched_policy(getpid(), &policy);
+            rc = SetTaskProfiles(tid, {get_sched_policy_profile_name(policy)}, true) ? 0 : -1;
+        }
 
-    if (rc) {
-        lasterr = errno;
+        if (rc) {
+            lasterr = errno;
+        }
     }
 
     if (setpriority(PRIO_PROCESS, tid, pri) < 0) {
diff --git a/libutils/include/utils/AndroidThreads.h b/libutils/include/utils/AndroidThreads.h
index a8d785175..3c30a2a85 100644
--- a/libutils/include/utils/AndroidThreads.h
+++ b/libutils/include/utils/AndroidThreads.h
@@ -78,7 +78,9 @@ extern void androidSetCreateThreadFunc(android_create_thread_fn func);
 // should be one of the ANDROID_PRIORITY constants.  Returns INVALID_OPERATION
 // if the priority set failed, else another value if just the group set failed;
 // in either case errno is set.  Thread ID zero means current thread.
-extern int androidSetThreadPriority(pid_t tid, int prio);
+// Parameter "change_policy" indicates if sched policy should be changed. It needs
+// not be checked again if the change is done elsewhere like activity manager.
+extern int androidSetThreadPriority(pid_t tid, int prio, bool change_policy = true);
 
 // Get the current priority of a particular thread. Returns one of the
 // ANDROID_PRIORITY constants or a negative result in case of error.