Address encountered deadlock issues with service use.

bundles/org.eclipse.equinox.ds.tests/.settings/org.eclipse.pde.ds.annotations.prefs

@@ -0,0 +1,8 @@
+classpath=true
+dsVersion=V1_3
+eclipse.preferences.version=1
+enabled=true
+generateBundleActivationPolicyLazy=true
+path=OSGI-INF
+validationErrorLevel=error
+validationErrorLevel.missingImplicitUnbindMethod=error

bundles/org.eclipse.equinox.ds.tests/META-INF/MANIFEST.MF

@@ -20,3 +20,10 @@ Export-Package: org.eclipse.equinox.ds.tests.tbc
 Bundle-RequiredExecutionEnvironment: JavaSE-1.8
 Eclipse-BundleShape: dir
 Automatic-Module-Name: org.eclipse.equinox.ds.tests
+Service-Component: OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator.xml,
+ OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5.xml

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1"/>
+   </service>
+   <reference cardinality="1..1" field="a" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2" name="a"/>
+   <reference cardinality="1..1" field="b" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4" name="b"/>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2"/>
+   </service>
+   <reference cardinality="0..n" field="c3s" field-option="update" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3" name="c3s" policy="dynamic"/>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3"/>
+   </service>
+   <reference cardinality="1..1" field="a" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component2" name="a"/>
+   <reference cardinality="1..1" field="b" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5" name="b"/>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component3"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" activate="activated" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation"/>
+   </service>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4"/>
+   </service>
+   <reference cardinality="1..1" field="a" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4$AwaitComponent5Activation" name="a"/>
+   <reference cardinality="1..1" field="b" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5" name="b"/>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component4"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" activate="activated" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator"/>
+   </service>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/OSGI-INF/org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.3.0" name="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5">
+   <service>
+      <provide interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5"/>
+   </service>
+   <reference cardinality="1..1" field="a" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5$ActivationStartedIndicator" name="a"/>
+   <reference cardinality="0..n" field="c1s" field-option="update" interface="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component1" name="c1s" policy="dynamic"/>
+   <implementation class="org.eclipse.equinox.ds.tests.LazyServiceComponentActivationDeadLockTest$Component5"/>
+</scr:component>

bundles/org.eclipse.equinox.ds.tests/build.properties

@@ -44,7 +44,8 @@ bin.includes = META-INF/,\
                scr_test/tb26.jar,\
                scr_test/tb27.jar,\
                test.xml,\
-               about.html
+               about.html,\
+               OSGI-INF/
 jars.compile.order = .,\
                      scr_test/tb1.jar,\
                      scr_test/tb1a.jar,\

bundles/org.eclipse.equinox.ds.tests/src/org/eclipse/equinox/ds/tests/AllTests.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 1997-2009 by ProSyst Software GmbH
+ * Copyright (c) 1997-2022 by ProSyst Software GmbH
  * http://www.prosyst.com
  *
  * This program and the accompanying materials
@@ -18,8 +18,12 @@
 import org.junit.runner.RunWith;
 import org.junit.runners.Suite;
 import org.junit.runners.Suite.SuiteClasses;
+
 @RunWith(Suite.class)
-@SuiteClasses(DSTest.class)
+@SuiteClasses({ //
+	DSTest.class, //
+	LazyServiceComponentActivationDeadLockTest.class //
+})
 public class AllTests {
-	//intentionally left blank
+	// intentionally left blank
 }

bundles/org.eclipse.equinox.ds.tests/src/org/eclipse/equinox/ds/tests/LazyServiceComponentActivationDeadLockTest.java

@@ -0,0 +1,211 @@
+/*******************************************************************************
+ * Copyright (c) 2022, 2022 Hannes Wellmann and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Hannes Wellmann - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.equinox.ds.tests;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.function.BiFunction;
+
+import org.junit.Test;
+import org.osgi.framework.Bundle;
+import org.osgi.framework.BundleContext;
+import org.osgi.framework.ServiceFactory;
+import org.osgi.framework.ServiceReference;
+import org.osgi.framework.ServiceRegistration;
+import org.osgi.service.component.annotations.Activate;
+import org.osgi.service.component.annotations.Component;
+import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.osgi.service.component.annotations.ReferencePolicy;
+
+public class LazyServiceComponentActivationDeadLockTest {
+
+	@Test
+	public void testServiceFactoryDeadLock() throws Exception {
+
+		class SimpleServiceFactory<T> implements ServiceFactory<T> {
+			private final BiFunction<Bundle, ServiceRegistration<T>, T> factory;
+
+			SimpleServiceFactory(BiFunction<Bundle, ServiceRegistration<T>, T> factory) {
+				this.factory = factory;
+			}
+
+			@Override
+			public T getService(Bundle bundle, ServiceRegistration<T> registration) {
+				return factory.apply(bundle, registration);
+			}
+
+			@Override
+			public void ungetService(Bundle bundle, ServiceRegistration<T> registration, T service) {
+			}
+
+		}
+
+		class Service1 {
+		}
+
+		class Service2 {
+		}
+
+		CountDownLatch l1 = new CountDownLatch(1);
+		CountDownLatch l2 = new CountDownLatch(1);
+		BundleContext ctx = DSTestsActivator.getContext();
+
+		ServiceFactory<Service1> factory1 = new SimpleServiceFactory<>((bundle, registration) -> {
+			countDownAndAwaitOther(l1, l2);
+			ctx.getService(ctx.getServiceReference(Service2.class));
+			return new Service1();
+		});
+		ServiceFactory<Service2> factory2 = new SimpleServiceFactory<>((bundle, registration) -> {
+			countDownAndAwaitOther(l2, l1);
+			ctx.getService(ctx.getServiceReference(Service1.class));
+			return new Service2();
+		});
+		ctx.registerService(Service1.class, factory1, null);
+		ctx.registerService(Service2.class, factory2, null);
+
+		ExecutorService executor = Executors.newFixedThreadPool(2);
+		try {
+			Future<Service1> service1 = executor.submit(() -> ctx.getService(ctx.getServiceReference(Service1.class)));
+			Future<Service2> service2 = executor.submit(() -> ctx.getService(ctx.getServiceReference(Service2.class)));
+			Service1 s1 = service1.get(5, TimeUnit.SECONDS); // times out in case of dead-lock
+			Service2 s2 = service2.get(5, TimeUnit.SECONDS); // times out in case of dead-lock
+			if (s1 != null && s2 != null) {
+				fail("At least one dead-locked component should be null");
+			}
+			// TODO: when we have a strategy to re-cover from the deadlock, check that both
+			// services are not null.
+		} finally {
+			executor.shutdown();
+		}
+	}
+
+	void countDownAndAwaitOther(CountDownLatch l1, CountDownLatch l2) {
+		l1.countDown();
+		try {
+			l2.await();
+		} catch (InterruptedException e) {
+		}
+	}
+
+	@Test
+	public void testLateBindingInSameBundleDeadLock() throws Exception {
+		BundleContext ctx = DSTestsActivator.getContext();
+		ServiceReference<Component1> reference = ctx.getServiceReference(Component1.class);
+
+		ExecutorService executor = Executors.newSingleThreadExecutor();
+		try {
+			Future<Component1> service = executor.submit(() -> ctx.getService(reference));
+			Component1 c1 = service.get(5, TimeUnit.SECONDS); // times out in case of dead-lock
+			// component might or might not be null depending on in which thread the
+			// DeadLock was detected and the SCR-ServiceFactory therefore threw an
+			// Exception.
+			if (c1 != null) {
+				// If the main-thread did not detect the dead-lock and therefore Component1 is
+				// successfully created, the multi-ref from its Comp2 to Comp3 must be empty and
+				// its Comp4 must have its Comp5 successfully created.
+				assertTrue(c1.a.c3s.isEmpty());
+				assertNotNull(c1.b.b);
+			}
+			// TODO: when we have a strategy to re-cover from the deadlock, check that c1 is
+			// never null and that c1.a.c3s is not empty and its only element has a Comp2
+			// and Comp5
+		} finally {
+			executor.shutdown();
+			// ctx.ungetService(reference);
+		}
+	}
+
+	@Component(service = Component1.class)
+	public static class Component1 {
+		@Reference
+		Component2 a; // activate first
+		@Reference
+		Component4 b; // activate second
+	}
+
+	@Component(service = Component2.class)
+	public static class Component2 {
+
+		@Reference(cardinality = ReferenceCardinality.MULTIPLE, policy = ReferencePolicy.DYNAMIC)
+		final List<Component3> c3s = new CopyOnWriteArrayList<>();
+	}
+
+	@Component(service = Component3.class)
+	public static class Component3 {
+
+		@Reference
+		Component2 a;
+
+		@Reference
+		Component5 b;
+	}
+
+	@Component(service = Component4.class)
+	public static class Component4 {
+
+		@Reference
+		Component5 b;
+
+		@Reference
+		AwaitComponent5Activation a; // ensure this reference is activated first
+
+		// The nested component ensures that the activation of this component's
+		// reference to Component5 starts only after the activation of Component5 has
+		// started in the SCR-Actor thread.
+
+		@Component(service = AwaitComponent5Activation.class)
+		public static class AwaitComponent5Activation {
+			@Activate
+			public void activated() throws InterruptedException {
+				Component5.ACTIVATION_STARTED.await();
+			}
+		}
+	}
+
+	@Component(service = Component5.class)
+	public static class Component5 {
+
+		@Reference(cardinality = ReferenceCardinality.MULTIPLE, policy = ReferencePolicy.DYNAMIC)
+		final List<Component1> c1s = new ArrayList<>();
+
+		@Reference
+		ActivationStartedIndicator a; // activate first
+
+		static final CountDownLatch ACTIVATION_STARTED = new CountDownLatch(1);
+		// Count-down is another component to let it happen when this component has
+		// started its activation but did not completed it.
+
+		@Component(service = ActivationStartedIndicator.class)
+		public static class ActivationStartedIndicator {
+
+			@Activate
+			public void activated() {
+				ACTIVATION_STARTED.countDown();
+			}
+		}
+	}
+
+}