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Commit 2356bf8b authored by Timothy Yiu's avatar Timothy Yiu
Browse files

Enable Process Observer onProcessStarted broadcast 

This change was previously reverted due to b/323925686 and has not been revisited since.

Looking at the bug, it seems like it is a concurrency issue where there are concurrent access to RemoteCallbackList's beginBroadcastInternal.

Adding synchronized block should resolve the issue.

Bug: 323959187
Bug: 323925686
Bug: 389579807
Test: atest FrameworksMockingServicesTests
Flag: android.app.enable_process_observer_broadcast_on_process_started
Change-Id: I706d8a3cda7418e30a95614a1c9303f0bec55537
parent c09deed1

core/java/android/app/activity_manager.aconfig

+7 −0
Original line number Diff line number Diff line
@@ -190,3 +190,10 @@ flag { 
         purpose: PURPOSE_BUGFIX

     }

}



flag {

     name: "enable_process_observer_broadcast_on_process_started"

     namespace: "system_performance"

     description: "Enable ProcessObserver's onProcessStarted callbacks."

     bug: "323959187"

}

services/core/java/com/android/server/am/ProcessList.java

+65 −37
Original line number Diff line number Diff line
@@ -793,6 +793,7 @@ public final class ProcessList { 
    final ProcessMap<ProcessRecord> mDyingProcesses = new ProcessMap<>();



    // Self locked with the inner lock within the RemoteCallbackList

    @GuardedBy("mProcessObservers")

    private final RemoteCallbackList<IProcessObserver> mProcessObservers =

            new RemoteCallbackList<>();
@@ -4980,12 +4981,16 @@ public final class ProcessList { 
    }



    void registerProcessObserver(IProcessObserver observer) {

        synchronized  (mProcessObservers) {

            mProcessObservers.register(observer);

        }

    }



    void unregisterProcessObserver(IProcessObserver observer) {

        synchronized (mProcessObservers) {

            mProcessObservers.unregister(observer);

        }

    }



    void dispatchProcessesChanged() {

        int numOfChanges;
@@ -5002,6 +5007,7 @@ public final class ProcessList { 
            }

        }



        synchronized (mProcessObservers) {

            int i = mProcessObservers.beginBroadcast();

            while (i > 0) {

                i--;
@@ -5019,7 +5025,8 @@ public final class ProcessList { 
                                observer.onForegroundActivitiesChanged(item.pid, item.uid,

                                        item.foregroundActivities);

                            }

                        if ((item.changes & ProcessChangeItem.CHANGE_FOREGROUND_SERVICES) != 0) {

                            if ((item.changes & ProcessChangeItem.CHANGE_FOREGROUND_SERVICES)

                                    != 0) {

                                if (DEBUG_PROCESS_OBSERVERS) {

                                    Slog.i(TAG_PROCESS_OBSERVERS,

                                            "FOREGROUND SERVICES CHANGED pid=" + item.pid + " uid="
@@ -5034,6 +5041,7 @@ public final class ProcessList { 
                }

            }

            mProcessObservers.finishBroadcast();

        }



        synchronized (mProcessChangeLock) {

            for (int j = 0; j < numOfChanges; j++) {
@@ -5122,10 +5130,29 @@ public final class ProcessList { 
    }



    void dispatchProcessStarted(ProcessRecord app, int pid) {

        // TODO(b/323959187) Add the implementation.

        if (!android.app.Flags.enableProcessObserverBroadcastOnProcessStarted()) {

            Slog.i(TAG, "ProcessObserver broadcast disabled");

            return;

        }

        synchronized (mProcessObservers) {

            int i = mProcessObservers.beginBroadcast();

            while (i > 0) {

                i--;

                final IProcessObserver observer = mProcessObservers.getBroadcastItem(i);

                if (observer != null) {

                    try {

                        observer.onProcessStarted(pid, app.uid, app.info.uid,

                                app.info.packageName, app.processName);

                    } catch (RemoteException e) {

                    }

                }

            }

            mProcessObservers.finishBroadcast();

        }

    }



    void dispatchProcessDied(int pid, int uid) {

        synchronized (mProcessObservers) {

            int i = mProcessObservers.beginBroadcast();

            while (i > 0) {

                i--;
@@ -5139,6 +5166,7 @@ public final class ProcessList { 
            }

            mProcessObservers.finishBroadcast();

        }

    }



    @GuardedBy(anyOf = {"mService", "mProcLock"})

    ArrayList<ProcessRecord> collectProcessesLOSP(int start, boolean allPkgs, String[] args) {

services/tests/mockingservicestests/src/com/android/server/am/ProcessObserverTest.java

+5 −1
Original line number Diff line number Diff line
@@ -42,6 +42,8 @@ import android.os.Binder; 
import android.os.Handler;

import android.os.HandlerThread;

import android.os.IBinder;

import android.platform.test.annotations.EnableFlags;

import android.platform.test.flag.junit.SetFlagsRule;

import android.util.Log;



import androidx.test.filters.MediumTest;
@@ -79,6 +81,8 @@ public class ProcessObserverTest { 
    @Rule

    public final ApplicationExitInfoTest.ServiceThreadRule

            mServiceThreadRule = new ApplicationExitInfoTest.ServiceThreadRule();

    @Rule

    public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();



    private Context mContext;

    private HandlerThread mHandlerThread;
@@ -239,8 +243,8 @@ public class ProcessObserverTest { 
    /**

     * Verify that a process start event is dispatched to process observers.

     */

    @Ignore("b/323959187")

    @Test

    @EnableFlags(android.app.Flags.FLAG_ENABLE_PROCESS_OBSERVER_BROADCAST_ON_PROCESS_STARTED)

    public void testNormal() throws Exception {

        ProcessRecord app = startProcess();

        verify(mProcessObserver).onProcessStarted(