Make IOnAssociationsChangedListener.onAssociationsChanged() blocking
Make IOnAssociationsChangedListener.onAssociationsChanged() blocking
(not "oneway") to make sure that the clients of the
addOnAssociationsChangedListener() API (@SystemAPI guarded by a
"signature" permission) are able to prevent race conditions that may
arise if their own clients (applications) effectively get notified
about the changes before system services do.
This is safe for 2 reasons:
1. The addOnAssociationsChangedListener() API is only available to the
system components (guarded by a "signature" permission).
See android.permission.MANAGE_COMPANION_DEVICES.
2. On the Java side addOnAssociationsChangedListener() in CDM takes an
Executor, and the proxy implementation of onAssociationsChanged()
simply "posts" a job to it.
See CompanionDeviceManager.OnAssociationsChangedListenerProxy class.
Bug: 214016641
Test: atest --iterations 10 CtsCompanionDeviceManagerCoreTestCases:AssociationsChangedListenerTest
Test: atest CtsCompanionDeviceManagerCoreTestCases
Test: atest CtsCompanionDeviceManagerUiAutomationTestCases
Test: atest CtsOsTestCases:CompanionDeviceManagerTest
Change-Id: I7c664e9b9c848f8f0291ff46a56ff47bae7db346
diff --git a/core/java/android/companion/IOnAssociationsChangedListener.aidl b/core/java/android/companion/IOnAssociationsChangedListener.aidl
index e6794b7..d369456 100644
--- a/core/java/android/companion/IOnAssociationsChangedListener.aidl
+++ b/core/java/android/companion/IOnAssociationsChangedListener.aidl
@@ -20,5 +20,22 @@
/** @hide */
interface IOnAssociationsChangedListener {
- oneway void onAssociationsChanged(in List<AssociationInfo> associations);
+
+ /*
+ * IMPORTANT: This method is intentionally NOT "oneway".
+ *
+ * The method is intentionally "blocking" to make sure that the clients of the
+ * addOnAssociationsChangedListener() API (@SystemAPI guarded by a "signature" permission) are
+ * able to prevent race conditions that may arise if their own clients (applications)
+ * effectively get notified about the changes before system services do.
+ *
+ * This is safe for 2 reasons:
+ * 1. The addOnAssociationsChangedListener() is only available to the system components
+ * (guarded by a "signature" permission).
+ * See android.permission.MANAGE_COMPANION_DEVICES.
+ * 2. On the Java side addOnAssociationsChangedListener() in CDM takes an Executor, and the
+ * proxy implementation of onAssociationsChanged() simply "post" a Runnable to it.
+ * See CompanionDeviceManager.OnAssociationsChangedListenerProxy class.
+ */
+ void onAssociationsChanged(in List<AssociationInfo> associations);
}
\ No newline at end of file