Add a holdback study for concurrent MessageQueue.

This is to evaluate the impact of concurrent MessageQueue on the system performance.

Change-Id: I61b7616b6e58d96cfd465dd1ba6dfee9c7f06a5b
Flag: android.os.message_queue_force_legacy
Bug: 336880969

2 files changed, 14 insertions, 0 deletions

diff --git a/core/java/android/os/CombinedMessageQueue/MessageQueue.java b/core/java/android/os/CombinedMessageQueue/MessageQueue.java
index 9ad2e7f82ce4..5c73de4669cd 100644
--- a/core/java/android/os/CombinedMessageQueue/MessageQueue.java
+++ b/core/java/android/os/CombinedMessageQueue/MessageQueue.java
@@ -126,6 +126,11 @@ public final class MessageQueue {
         // We can lift this restriction in the future after we've made it possible for test authors
         // to test Looper and MessageQueue without resorting to reflection.
 
+        // Holdback study.
+        if (mUseConcurrent && Flags.messageQueueForceLegacy()) {
+            mUseConcurrent = false;
+        }
+
         mQuitAllowed = quitAllowed;
         mPtr = nativeInit();
     }
diff --git a/core/java/android/os/flags.aconfig b/core/java/android/os/flags.aconfig
index 118167d02c48..01445069af67 100644
--- a/core/java/android/os/flags.aconfig
+++ b/core/java/android/os/flags.aconfig
@@ -4,6 +4,15 @@ container: "system"
 
 # keep-sorted start block=yes newline_separated=yes
 flag {
+     # Holdback study for concurrent MessageQueue.
+     # Do not promote beyond trunkfood.
+     namespace: "system_performance"
+     name: "message_queue_force_legacy"
+     description: "Whether to holdback concurrent MessageQueue (force legacy)."
+     bug: "336880969"
+}
+
+flag {
     name: "adpf_gpu_report_actual_work_duration"
     is_exported: true
     namespace: "game"