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Commit 722533f2 authored by satayev's avatar satayev
Browse files

Ignore requests to start an already started system service. 

For apex-system-services, we allow them to be explicitly started in
SystemService if there is a dependency on them from the rest of the
framework during dessert development. We also need to preserve their
manifest declaration for any previously launched dessert releases.

To avoid starting the same service multiple times, keep track of which
services have been started in SystemServiceManager and ignore
duplicates.

See go/updatable-system-services#bookmark=id.dnv20ia7siqd for more
details.

Bug: 192880996
Test: presubmit
Change-Id: I0a9e48eac9fd5739e2c35818fa483a8e479c13a1
parent 3350e9f7

services/core/java/com/android/server/SystemServiceManager.java

+14 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ import android.os.Environment; 
import android.os.SystemClock;

import android.os.Trace;

import android.os.UserHandle;

import android.util.ArraySet;

import android.util.EventLog;

import android.util.IndentingPrintWriter;

import android.util.Slog;
@@ -47,6 +48,7 @@ import java.lang.reflect.InvocationTargetException; 
import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import java.util.Set;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.TimeUnit;
@@ -94,6 +96,7 @@ public final class SystemServiceManager implements Dumpable { 


    // Services that should receive lifecycle events.

    private List<SystemService> mServices;

    private Set<String> mServiceClassnames;



    private int mCurrentPhase = -1;
@@ -116,6 +119,7 @@ public final class SystemServiceManager implements Dumpable { 
    SystemServiceManager(Context context) {

        mContext = context;

        mServices = new ArrayList<>();

        mServiceClassnames = new ArraySet<>();

        // Disable using the thread pool for low ram devices

        sUseLifecycleThreadPool = sUseLifecycleThreadPool

                && !ActivityManager.isLowRamDeviceStatic();
@@ -210,8 +214,17 @@ public final class SystemServiceManager implements Dumpable { 
    }



    public void startService(@NonNull final SystemService service) {

        // Check if already started

        String className = service.getClass().getName();

        if (mServiceClassnames.contains(className)) {

            Slog.i(TAG, "Not starting an already started service " + className);

            return;

        }

        mServiceClassnames.add(className);



        // Register it.

        mServices.add(service);



        // Start it.

        long time = SystemClock.elapsedRealtime();

        try {
@@ -225,6 +238,7 @@ public final class SystemServiceManager implements Dumpable { 


    /** Disallow starting new services after this call. */

    void sealStartedServices() {

        mServiceClassnames = Collections.emptySet();

        mServices = Collections.unmodifiableList(mServices);

    }

services/java/com/android/server/SystemServer.java

+0 −1
Original line number Diff line number Diff line
@@ -3053,7 +3053,6 @@ public final class SystemServer implements Dumpable { 
    private void startApexServices(@NonNull TimingsTraceAndSlog t) {

        t.traceBegin("startApexServices");

        Map<String, String> services = ApexManager.getInstance().getApexSystemServices();

        // TODO(satayev): filter out already started services

        // TODO(satayev): introduce android:order for services coming the same apexes

        for (String name : new TreeSet<>(services.keySet())) {

            String jarPath = services.get(name);

services/tests/servicestests/src/com/android/server/SystemServiceManagerTest.java

+34 −5
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ import android.test.AndroidTestCase; 
import org.junit.Test;



import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.atomic.AtomicInteger;





/**
@@ -32,24 +33,52 @@ public class SystemServiceManagerTest extends AndroidTestCase { 


    private static final String TAG = "SystemServiceManagerTest";



    private final SystemServiceManager mSystemServiceManager =

            new SystemServiceManager(getContext());



    @Test

    public void testSealStartedServices() throws Exception {

        SystemServiceManager manager = new SystemServiceManager(getContext());

        // must be effectively final, since it's changed from inner class below

        AtomicBoolean serviceStarted = new AtomicBoolean(false);

        SystemService service = new SystemService(getContext()) {

        SystemService service1 = new SystemService(getContext()) {

            @Override

            public void onStart() {

                serviceStarted.set(true);

            }

        };

        SystemService service2 = new SystemService(getContext()) {

            @Override

            public void onStart() {

                throw new IllegalStateException("Second service must not be called");

            }

        };



        // started services have their #onStart methods called

        manager.startService(service);

        mSystemServiceManager.startService(service1);

        assertTrue(serviceStarted.get());



        // however, after locking started services, it is not possible to start a new service

        manager.sealStartedServices();

        assertThrows(UnsupportedOperationException.class, () -> manager.startService(service));

        mSystemServiceManager.sealStartedServices();

        assertThrows(UnsupportedOperationException.class,

                () -> mSystemServiceManager.startService(service2));

    }



    @Test

    public void testDuplicateServices() throws Exception {

        AtomicInteger counter = new AtomicInteger(0);

        SystemService service = new SystemService(getContext()) {

            @Override

            public void onStart() {

                counter.incrementAndGet();

            }

        };



        mSystemServiceManager.startService(service);

        assertEquals(1, counter.get());



        // manager does not start the same service twice

        mSystemServiceManager.startService(service);

        assertEquals(1, counter.get());

    }



}