Camera / UidObserver: Add the ability to subscribe to specific UIDs

UidObserver sends updates about the state of all packages installed on
the system. In the case of the cameraserver, we only care about a
handful of them. The current status quo is to filter out these callbacks
but there is a significant IPC cost that is not addressed by that
approach.

This patch adds new entrypoints to ActivityManagerService to listen only
to specified UIDs. This set of uids can be updated dynamically.

Change-Id: I669f27b94fb691187bb77942f53ebc02cb90ace4
Bug: 274486653
Test: -- on physical device:
      -- testCamera2AccessCallbackInSplitMode x10
      -- ActivityManagerServiceTest
      -- ActivityManagerProcessStateTest
      -- ActivityManagerFgsBgStartTest
      -- UidObserverControllerTest
      -- Alternate focus in split screen between Camera2 + GCA x20
Ignore-AOSP: Soak time in U

4 files changed, 106 insertions, 0 deletions

diff --git a/libs/binder/ActivityManager.cpp b/libs/binder/ActivityManager.cpp
index e45a656d29..aca5009148 100644
--- a/libs/binder/ActivityManager.cpp
+++ b/libs/binder/ActivityManager.cpp
@@ -75,6 +75,20 @@ status_t ActivityManager::registerUidObserver(const sp<IUidObserver>& observer,
     return DEAD_OBJECT;
 }
 
+status_t ActivityManager::registerUidObserverForUids(const sp<IUidObserver>& observer,
+                                                     const int32_t event, const int32_t cutpoint,
+                                                     const String16& callingPackage,
+                                                     const int32_t uids[], size_t nUids,
+                                                     /*out*/ sp<IBinder>& observerToken) {
+    sp<IActivityManager> service = getService();
+    if (service != nullptr) {
+        return service->registerUidObserverForUids(observer, event, cutpoint, callingPackage, uids,
+                                                   nUids, observerToken);
+    }
+    // ActivityManagerService appears dead. Return usual error code for dead service.
+    return DEAD_OBJECT;
+}
+
 status_t ActivityManager::unregisterUidObserver(const sp<IUidObserver>& observer)
 {
     sp<IActivityManager> service = getService();
@@ -85,6 +99,26 @@ status_t ActivityManager::unregisterUidObserver(const sp<IUidObserver>& observer
     return DEAD_OBJECT;
 }
 
+status_t ActivityManager::addUidToObserver(const sp<IBinder>& observerToken,
+                                           const String16& callingPackage, int32_t uid) {
+    sp<IActivityManager> service = getService();
+    if (service != nullptr) {
+        return service->addUidToObserver(observerToken, callingPackage, uid);
+    }
+    // ActivityManagerService appears dead. Return usual error code for dead service.
+    return DEAD_OBJECT;
+}
+
+status_t ActivityManager::removeUidFromObserver(const sp<IBinder>& observerToken,
+                                                const String16& callingPackage, int32_t uid) {
+    sp<IActivityManager> service = getService();
+    if (service != nullptr) {
+        return service->removeUidFromObserver(observerToken, callingPackage, uid);
+    }
+    // ActivityManagerService appears dead. Return usual error code for dead service.
+    return DEAD_OBJECT;
+}
+
 bool ActivityManager::isUidActive(const uid_t uid, const String16& callingPackage)
 {
     sp<IActivityManager> service = getService();
diff --git a/libs/binder/IActivityManager.cpp b/libs/binder/IActivityManager.cpp
index ebdaa4cc99..84900a72ff 100644
--- a/libs/binder/IActivityManager.cpp
+++ b/libs/binder/IActivityManager.cpp
@@ -77,6 +77,30 @@ public:
          return OK;
     }
 
+    virtual status_t registerUidObserverForUids(const sp<IUidObserver>& observer,
+                                                const int32_t event, const int32_t cutpoint,
+                                                const String16& callingPackage,
+                                                const int32_t uids[], size_t nUids,
+                                                /*out*/ sp<IBinder>& observerToken) {
+         Parcel data, reply;
+         data.writeInterfaceToken(IActivityManager::getInterfaceDescriptor());
+         data.writeStrongBinder(IInterface::asBinder(observer));
+         data.writeInt32(event);
+         data.writeInt32(cutpoint);
+         data.writeString16(callingPackage);
+         data.writeInt32Array(nUids, uids);
+         status_t err =
+                 remote()->transact(REGISTER_UID_OBSERVER_FOR_UIDS_TRANSACTION, data, &reply);
+         if (err != NO_ERROR || ((err = reply.readExceptionCode()) != NO_ERROR)) {
+             return err;
+         }
+         err = reply.readStrongBinder(&observerToken);
+         if (err != NO_ERROR || ((err = reply.readExceptionCode()) != NO_ERROR)) {
+             return err;
+         }
+         return OK;
+    }
+
     virtual status_t unregisterUidObserver(const sp<IUidObserver>& observer)
     {
          Parcel data, reply;
@@ -89,6 +113,34 @@ public:
          return OK;
     }
 
+    virtual status_t addUidToObserver(const sp<IBinder>& observerToken,
+                                      const String16& callingPackage, int32_t uid) {
+         Parcel data, reply;
+         data.writeInterfaceToken(IActivityManager::getInterfaceDescriptor());
+         data.writeStrongBinder(observerToken);
+         data.writeString16(callingPackage);
+         data.writeInt32(uid);
+         status_t err = remote()->transact(ADD_UID_TO_OBSERVER_TRANSACTION, data, &reply);
+         if (err != NO_ERROR || ((err = reply.readExceptionCode()) != NO_ERROR)) {
+             return err;
+         }
+         return OK;
+    }
+
+    virtual status_t removeUidFromObserver(const sp<IBinder>& observerToken,
+                                           const String16& callingPackage, int32_t uid) {
+         Parcel data, reply;
+         data.writeInterfaceToken(IActivityManager::getInterfaceDescriptor());
+         data.writeStrongBinder(observerToken);
+         data.writeString16(callingPackage);
+         data.writeInt32(uid);
+         status_t err = remote()->transact(REMOVE_UID_FROM_OBSERVER_TRANSACTION, data, &reply);
+         if (err != NO_ERROR || ((err = reply.readExceptionCode()) != NO_ERROR)) {
+             return err;
+         }
+         return OK;
+    }
+
     virtual bool isUidActive(const uid_t uid, const String16& callingPackage)
     {
          Parcel data, reply;
diff --git a/libs/binder/include_activitymanager/binder/ActivityManager.h b/libs/binder/include_activitymanager/binder/ActivityManager.h
index 5dfbd44dc4..9c634c7238 100644
--- a/libs/binder/include_activitymanager/binder/ActivityManager.h
+++ b/libs/binder/include_activitymanager/binder/ActivityManager.h
@@ -82,7 +82,15 @@ public:
                              const int32_t event,
                              const int32_t cutpoint,
                              const String16& callingPackage);
+    status_t registerUidObserverForUids(const sp<IUidObserver>& observer, const int32_t event,
+                                        const int32_t cutpoint, const String16& callingPackage,
+                                        const int32_t uids[], size_t nUids,
+                                        /*out*/ sp<IBinder>& observerToken);
     status_t unregisterUidObserver(const sp<IUidObserver>& observer);
+    status_t addUidToObserver(const sp<IBinder>& observerToken, const String16& callingPackage,
+                              int32_t uid);
+    status_t removeUidFromObserver(const sp<IBinder>& observerToken, const String16& callingPackage,
+                                   int32_t uid);
     bool isUidActive(const uid_t uid, const String16& callingPackage);
     int getUidProcessState(const uid_t uid, const String16& callingPackage);
     status_t checkPermission(const String16& permission, const pid_t pid, const uid_t uid, int32_t* outResult);
diff --git a/libs/binder/include_activitymanager/binder/IActivityManager.h b/libs/binder/include_activitymanager/binder/IActivityManager.h
index 20d12aea9a..07450c6af9 100644
--- a/libs/binder/include_activitymanager/binder/IActivityManager.h
+++ b/libs/binder/include_activitymanager/binder/IActivityManager.h
@@ -35,7 +35,16 @@ public:
                                      const int32_t event,
                                      const int32_t cutpoint,
                                      const String16& callingPackage) = 0;
+    virtual status_t registerUidObserverForUids(const sp<IUidObserver>& observer,
+                                                const int32_t event, const int32_t cutpoint,
+                                                const String16& callingPackage,
+                                                const int32_t uids[], size_t nUids,
+                                                /*out*/ sp<IBinder>& observerToken) = 0;
     virtual status_t unregisterUidObserver(const sp<IUidObserver>& observer) = 0;
+    virtual status_t addUidToObserver(const sp<IBinder>& observerToken,
+                                      const String16& callingPackage, int32_t uid) = 0;
+    virtual status_t removeUidFromObserver(const sp<IBinder>& observerToken,
+                                           const String16& callingPackage, int32_t uid) = 0;
     virtual bool isUidActive(const uid_t uid, const String16& callingPackage) = 0;
     virtual int32_t getUidProcessState(const uid_t uid, const String16& callingPackage) = 0;
     virtual status_t checkPermission(const String16& permission,
@@ -51,6 +60,9 @@ public:
         OPEN_CONTENT_URI_TRANSACTION = IBinder::FIRST_CALL_TRANSACTION,
         REGISTER_UID_OBSERVER_TRANSACTION,
         UNREGISTER_UID_OBSERVER_TRANSACTION,
+        REGISTER_UID_OBSERVER_FOR_UIDS_TRANSACTION,
+        ADD_UID_TO_OBSERVER_TRANSACTION,
+        REMOVE_UID_FROM_OBSERVER_TRANSACTION,
         IS_UID_ACTIVE_TRANSACTION,
         GET_UID_PROCESS_STATE_TRANSACTION,
         CHECK_PERMISSION_TRANSACTION,