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Posted to commits@polygene.apache.org by ni...@apache.org on 2018/05/04 02:22:11 UTC

[04/13] polygene-java git commit: POLYGENE-304 : Added library-execution with 3 initial features.

POLYGENE-304 : Added library-execution with 3 initial features.


Project: http://git-wip-us.apache.org/repos/asf/polygene-java/repo
Commit: http://git-wip-us.apache.org/repos/asf/polygene-java/commit/db99803f
Tree: http://git-wip-us.apache.org/repos/asf/polygene-java/tree/db99803f
Diff: http://git-wip-us.apache.org/repos/asf/polygene-java/diff/db99803f

Branch: refs/heads/develop
Commit: db99803fe4a4dd698c4e5694345c1672561483a2
Parents: dcea137
Author: niclas <ni...@hedhman.org>
Authored: Thu Apr 26 12:57:59 2018 +0800
Committer: niclas <ni...@hedhman.org>
Committed: Thu Apr 26 12:57:59 2018 +0800

----------------------------------------------------------------------
 .../apache/polygene/api/concern/ConcernOf.java  |   4 +-
 libraries/execution/build.gradle                |  37 +++
 libraries/execution/dev-status.xml              |  38 +++
 libraries/execution/src/docs/execution.txt      |  68 ++++++
 .../polygene/library/execution/Retry.java       |  66 +++++
 .../library/execution/RetryConcern.java         |  78 ++++++
 .../assembly/ExecutionServiceAssembler.java     | 242 +++++++++++++++++++
 .../ScheduledExecutionServiceAssembler.java     | 140 +++++++++++
 .../library/execution/ExecutionServiceTest.java |  51 ++++
 .../polygene/library/execution/RetryTest.java   | 184 ++++++++++++++
 .../ScheduledExecutionServiceTest.java          |  46 ++++
 manual/src/docs/userguide/libraries.txt         |   4 +
 settings.gradle                                 |   1 +
 13 files changed, 957 insertions(+), 2 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/core/api/src/main/java/org/apache/polygene/api/concern/ConcernOf.java
----------------------------------------------------------------------
diff --git a/core/api/src/main/java/org/apache/polygene/api/concern/ConcernOf.java b/core/api/src/main/java/org/apache/polygene/api/concern/ConcernOf.java
index e872308..01c90f7 100644
--- a/core/api/src/main/java/org/apache/polygene/api/concern/ConcernOf.java
+++ b/core/api/src/main/java/org/apache/polygene/api/concern/ConcernOf.java
@@ -40,7 +40,7 @@ public abstract class ConcernOf<T>
      * the next concern in the chain or the mixin
      * to be invoked.
      */
-    final
+    @SuppressWarnings( "ConstantConditions" )
     @ConcernFor
-    protected T next = null;
+    protected final T next = null;
 }

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/build.gradle
----------------------------------------------------------------------
diff --git a/libraries/execution/build.gradle b/libraries/execution/build.gradle
new file mode 100644
index 0000000..6863209
--- /dev/null
+++ b/libraries/execution/build.gradle
@@ -0,0 +1,37 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *
+ */
+
+apply plugin: 'polygene-library'
+
+description = "Apache Polygene™ Execution Library provides common set of execution primitives and services."
+
+jar { manifest { name = "Apache Polygene™ Library - Constraints"}}
+
+dependencies {
+  api polygene.core.bootstrap
+
+  api libraries.commons_validator
+
+  runtimeOnly polygene.core.runtime
+
+  testImplementation polygene.core.testsupport
+
+  testRuntimeOnly libraries.logback
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/dev-status.xml
----------------------------------------------------------------------
diff --git a/libraries/execution/dev-status.xml b/libraries/execution/dev-status.xml
new file mode 100644
index 0000000..8a476df
--- /dev/null
+++ b/libraries/execution/dev-status.xml
@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<!--
+  ~  Licensed to the Apache Software Foundation (ASF) under one
+  ~  or more contributor license agreements.  See the NOTICE file
+  ~  distributed with this work for additional information
+  ~  regarding copyright ownership.  The ASF licenses this file
+  ~  to you under the Apache License, Version 2.0 (the
+  ~  "License"); you may not use this file except in compliance
+  ~  with the License.  You may obtain a copy of the License at
+  ~
+  ~       http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~  Unless required by applicable law or agreed to in writing, software
+  ~  distributed under the License is distributed on an "AS IS" BASIS,
+  ~  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~  See the License for the specific language governing permissions and
+  ~  limitations under the License.
+  ~
+  ~
+  -->
+<module xmlns="http://polygene.apache.org/schemas/2008/dev-status/1"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:schemaLocation="http://polygene.apache.org/schemas/2008/dev-status/1
+        http://polygene.apache.org/schemas/2008/dev-status/1/dev-status.xsd">
+  <status>
+    <!--none,early,beta,stable,mature-->
+    <codebase>beta</codebase>
+
+    <!-- none, brief, good, complete -->
+    <documentation>good</documentation>
+
+    <!-- none, some, good, complete -->
+    <unittests>some</unittests>
+  </status>
+  <licenses>
+    <license>ALv2</license>
+  </licenses>
+</module>

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/docs/execution.txt
----------------------------------------------------------------------
diff --git a/libraries/execution/src/docs/execution.txt b/libraries/execution/src/docs/execution.txt
new file mode 100644
index 0000000..998c11d
--- /dev/null
+++ b/libraries/execution/src/docs/execution.txt
@@ -0,0 +1,68 @@
+///////////////////////////////////////////////////////////////
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+///////////////////////////////////////////////////////////////
+
+[[library-execution,Execution Library]]
+= Execution =
+
+== @Retry ==
+Any method can be annotated with the @Retry annotation, which means that if there is an exception thrown, then
+the method should be called again, for a max number of times.
+
+The value() defines how many times the method will be called, if retry is triggered by the on() and unless()
+parameters.
+
+The backoff() parameter is available to slow down the retries, which is useful for network operations or
+external systems that may still need more time to become available. The default is no backoff is deployed and retries
+are executed as fast as possible.
+
+The on() parameter defines which Throwable and subclasses should be considered for retrying the method call. The
+default is all Throwables.
+
+The unless() parameter negates the on() parameter, and if a subclass of any Throwable listed in unless() is thrown
+then the retry operation(s) will not take effect.
+
+== ExecutionService ==
+The =ExecutionService= is the =java.util.concurrent.ExecutorService= provided simply as a flexible assembler for
+configuration of it.
+
+=== Configuration Parameters ===
+The Configuration parameters are available in the =ExecutionServiceAssembler= via a fluent API (DSL), with the
+following methods
+
+[snippet,java]
+----
+source=libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ExecutionServiceAssembler.java
+tag=configuration
+----
+
+
+== ScheduledExecutionService ==
+The =ScheduledExecutionService= is the =java.util.concurrent.ScheduledExecutorService= provided simply as a flexible
+assembler for configuration of it.
+
+
+=== Configuration Parameters ===
+The Configuration parameters are available in the =ScheduledExecutionService= via a fluent API (DSL), with the
+following methods
+
+[snippet,java]
+----
+source=libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ScheduledExecutionService.java
+tag=configuration
+----

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/main/java/org/apache/polygene/library/execution/Retry.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/main/java/org/apache/polygene/library/execution/Retry.java b/libraries/execution/src/main/java/org/apache/polygene/library/execution/Retry.java
new file mode 100644
index 0000000..d283273
--- /dev/null
+++ b/libraries/execution/src/main/java/org/apache/polygene/library/execution/Retry.java
@@ -0,0 +1,66 @@
+package org.apache.polygene.library.execution;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.Inherited;
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import static java.lang.annotation.ElementType.METHOD;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+/**
+ * &#64;Retry is a method annotation to automatically call the method again if an exception was thrown.
+ * <p>
+ * By default, the method will be called twice if any {@link java.lang.Throwable} is thrown. By setting
+ * the value, one can increase that number, and the {@link #on()} and {@link #unless()} parameters can
+ * be used to select which Throwable (incl its subtypes) the retry will happen on.
+ * </p>
+ * <p>
+ *     This can only be applied to idempotent methods, and keeping in mind the ordering of Concerns may
+ *     be very significant. E.g. If the {@link RetryConcern} is "around" the
+ *     {@link org.apache.polygene.api.unitofwork.concern.UnitOfWorkConcern} then depending on the parameters on
+ *     the {@link org.apache.polygene.api.unitofwork.concern.UnitOfWorkPropagation} will determine if the
+ *     method is still idempotent or not, in particular
+ *     {@link org.apache.polygene.api.unitofwork.concern.UnitOfWorkPropagation.Propagation#REQUIRES_NEW}. Furthermore,
+ *     {@link org.apache.polygene.api.unitofwork.concern.UnitOfWorkPropagation} has its own Retry mechanism independent
+ *     of this one.
+ * </p>
+ */
+@Retention( RUNTIME )
+@Target( METHOD )
+@Inherited
+@Documented
+public @interface Retry
+{
+    /**
+     * Number of times that the method should be called.
+     * <p>
+     *     This number must be 1 or greater, otherwise an {@link IllegalArgumentException} is thrown.
+     * </p>
+     */
+    int value() default 2;
+
+    /**
+     * List of Throwables that should trigger the Retry operation.
+     * <p>
+     * Default: All Throwables.
+     * </p>
+     */
+    Class<? extends Throwable>[] on() default { Throwable.class };
+
+    /**
+     * List of Throwables that should NOT trigger the Retry operation, even if they are subclasses found in the on() value
+     * <p>
+     * Default: none.
+     * </p>
+     */
+    Class<? extends Throwable>[] unless() default {};
+
+    /**
+     * Slowing down of retries.
+     * <p>
+     *     If the backoff is greater than 0 (default), there will be a successive backoff of retrying the call,
+     *     and starting with backoff() milliseconds, the sleep time between tries will double for each try.
+     */
+    int backoff() default 0;
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/main/java/org/apache/polygene/library/execution/RetryConcern.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/main/java/org/apache/polygene/library/execution/RetryConcern.java b/libraries/execution/src/main/java/org/apache/polygene/library/execution/RetryConcern.java
new file mode 100644
index 0000000..0d995ae
--- /dev/null
+++ b/libraries/execution/src/main/java/org/apache/polygene/library/execution/RetryConcern.java
@@ -0,0 +1,78 @@
+package org.apache.polygene.library.execution;
+
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.stream.Collectors;
+import org.apache.polygene.api.common.AppliesTo;
+import org.apache.polygene.api.concern.ConcernOf;
+import org.apache.polygene.api.injection.scope.Invocation;
+
+import static org.apache.polygene.api.util.Classes.classHierarchy;
+
+@AppliesTo( Retry.class )
+public class RetryConcern extends ConcernOf<InvocationHandler>
+    implements InvocationHandler
+{
+    private final int retries;
+    private final HashSet<Class<? extends Throwable>> on;
+    private final HashSet<Object> unless;
+    private final int backoff;
+
+    @SuppressWarnings( "unchecked" )
+    public RetryConcern( @Invocation Retry annotation )
+    {
+        this.retries = annotation.value();
+        if( retries < 1 )
+        {
+            throw new IllegalArgumentException( "@Retry must have a positive value greater than zero." );
+        }
+        this.on = new HashSet<>();
+        List<Class<? extends Throwable>> on = Arrays.asList( annotation.on() );
+        this.on.addAll( on );
+
+        this.unless = new HashSet<>();
+        List<Class<? extends Throwable>> unless = Arrays.asList( annotation.unless() );
+        this.unless.addAll( unless );
+        this.backoff = annotation.backoff();
+    }
+
+    @Override
+    @SuppressWarnings( { "SuspiciousMethodCalls", "ConstantConditions" } )
+    public Object invoke( Object o, Method method, Object[] objects )
+        throws Throwable
+    {
+        int count = retries;
+        long sleep = backoff;
+        while( true )
+        {
+            try
+            {
+                return next.invoke( o, method, objects );
+            }
+            catch( Throwable e )
+            {
+                --count;
+                List<Class<?>> types = classHierarchy( e.getClass() ).collect( Collectors.toList() );
+                for( Class<?> type : types )
+                {
+                    if( this.unless.contains( type ) )
+                    {
+                        throw e;
+                    }
+                    if( count == 0 && this.on.contains( type ))
+                    {
+                        throw e;
+                    }
+                }
+                if( sleep > 0 )
+                {
+                    Thread.sleep( sleep );
+                    sleep = sleep * 2;
+                }
+            }
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ExecutionServiceAssembler.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ExecutionServiceAssembler.java b/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ExecutionServiceAssembler.java
new file mode 100644
index 0000000..22832ff
--- /dev/null
+++ b/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ExecutionServiceAssembler.java
@@ -0,0 +1,242 @@
+package org.apache.polygene.library.execution.assembly;
+
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ThreadFactory;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.TimeUnit;
+import org.apache.polygene.api.service.ImportedServiceDescriptor;
+import org.apache.polygene.api.service.ServiceImporter;
+import org.apache.polygene.api.service.ServiceImporterException;
+import org.apache.polygene.bootstrap.Assembler;
+import org.apache.polygene.bootstrap.Assemblers;
+import org.apache.polygene.bootstrap.AssemblyException;
+import org.apache.polygene.bootstrap.ModuleAssembly;
+
+public class ExecutionServiceAssembler extends Assemblers.VisibilityIdentityConfig<ExecutionServiceAssembler>
+    implements Assembler
+{
+
+    private ThreadFactory factory;
+    private RejectedExecutionHandler rejectedExecutionHandler;
+    private int coreThreads = 3;
+    private int maxThreads = 10;
+    private int maxTasks = 1000;
+    private long time = 1000;
+    private TimeUnit unit = TimeUnit.MILLISECONDS;
+    private ThreadGroup group;
+    private BlockingQueue<Runnable> queue;
+
+    @Override
+    public void assemble( ModuleAssembly module )
+        throws AssemblyException
+    {
+        module.importedServices( ExecutorService.class )
+              .importedBy( ThreadPoolExecutorImporter.class )
+              .setMetaInfo( this )
+        ;
+    }
+
+    /**
+     * Number of core threads, i.e. threads that are not removed if idle, to be used.
+     *
+     * @param threads core threads to use
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Number of core threads, i.e. threads that are not removed if idle, to be used.
+    public ExecutionServiceAssembler withCoreThreads( int threads )
+    // END SNIPPET: configuration
+    {
+        this.coreThreads = threads;
+        return this;
+    }
+
+    /**
+     * Maximum number of threads to be used.
+     *
+     * @param threads max threads to use
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Maximum number of threads to be used.
+    public ExecutionServiceAssembler withMaxThreads( int threads )
+    // END SNIPPET: configuration
+    {
+        this.maxThreads = threads;
+        return this;
+    }
+
+    /**
+     * Provide a custom ThreadFactory.
+     * <p>
+     * If defined, the {@link #inThreadGroup(ThreadGroup)} parameter will be ignored.
+     * </p>
+     *
+     * @param factory The thread factory to use, when creating threads.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Provide a custom ThreadFactory. If defined, the inThreadGroup parameter will be ignored.
+    public ExecutionServiceAssembler withThreadFactory( ThreadFactory factory )
+    // END SNIPPET: configuration
+    {
+        this.factory = factory;
+        return this;
+    }
+
+    /**
+     * Provide a custom {@link RejectedExecutionHandler}, or one of the pre-defined policies
+     *
+     * @param handler the custom {@link RejectedExecutionHandler} to use.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Provide a custom RejectedExecutionHandler, or one of the pre-defined policies
+    public ExecutionServiceAssembler withRejectedExecutionHandler( RejectedExecutionHandler handler )
+    // END SNIPPET: configuration
+    {
+        this.rejectedExecutionHandler = handler;
+        return this;
+    }
+
+    /**
+     * Max number of entries in queue.
+     * <p>
+     * Blocking occurs if more submissions are given.
+     * </p>
+     * <p>
+     * If a custom queue is defined, then this parameter will be ignored.
+     * </p>
+     *
+     * @param maxTasks Max number of tasks that can be added to the queue before blocking occurs.
+     * @return Fluent API
+     * @see LinkedBlockingQueue which is backing the {@link ThreadPoolExecutor} if a custom one is not provided.
+     */
+    // START SNIPPET: configuration
+    // Max number of entries in queue. Blocking occurs if more submissions given
+    public ExecutionServiceAssembler withMaxQueueSize( int maxTasks )
+    // END SNIPPET: configuration
+    {
+        this.maxTasks = maxTasks;
+        return this;
+    }
+
+    /**
+     * Provide custom queue.
+     * <p>
+     * If a custom queue is defined, then the {@link #withMaxQueueSize(int)} parameter will be ignored.
+     * </p>
+     *
+     * @param queue The custom queue to use.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Provide custom queue. If used, the withMaxQueueSize is ignored
+    public ExecutionServiceAssembler withQueue( BlockingQueue<Runnable> queue )
+    // END SNIPPET: configuration
+    {
+        this.queue = queue;
+        return this;
+    }
+
+    /**
+     * For how long the threads should be kept around idling before discarded
+     *
+     * @param time The time to keep alive
+     * @param unit The unit in which the 'time' argument is expressed.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // For how long the threads should be kept around idling before discarded
+    public ExecutionServiceAssembler withKeepAliveTime( int time, TimeUnit unit )
+    // END SNIPPET: configuration
+    {
+        this.time = time;
+        this.unit = unit;
+        return this;
+    }
+
+    /**
+     * Thread Group to create the threads in.
+     * <p>
+     * If a custom ThreadFactory is given, {@link #withThreadFactory(ThreadFactory)} then this parameter is ignored.
+     * </p>
+     *
+     * @param group The thread group that all threads should be placed in.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Thread Group to create the threads in
+    public ExecutionServiceAssembler inThreadGroup( ThreadGroup group )
+    // END SNIPPET: configuration
+    {
+        this.group = group;
+        return this;
+    }
+
+    private static class ThreadPoolExecutorImporter
+        implements ServiceImporter
+    {
+        long count = 0;
+
+        @Override
+        public Object importService( ImportedServiceDescriptor serviceDescriptor )
+            throws ServiceImporterException
+        {
+            ExecutionServiceAssembler metaInfo = serviceDescriptor.metaInfo( ExecutionServiceAssembler.class );
+            ThreadGroup group;
+            if( metaInfo.group == null )
+            {
+                group = new ThreadGroup( "tg-" + metaInfo.identity() );
+            }
+            else
+            {
+                group = metaInfo.group;
+            }
+            ThreadFactory factory = metaInfo.factory;
+            if( factory == null )
+            {
+                factory = runnable -> new Thread( group, runnable, "t-" + count++ );
+            }
+            BlockingQueue<Runnable> queue;
+            if( metaInfo.queue == null )
+            {
+                queue = new LinkedBlockingQueue<>( metaInfo.maxTasks );
+            }
+            else
+            {
+                queue = metaInfo.queue;
+            }
+            if( metaInfo.rejectedExecutionHandler == null )
+            {
+                return new ThreadPoolExecutor( metaInfo.coreThreads,
+                                               metaInfo.maxThreads,
+                                               metaInfo.time,
+                                               metaInfo.unit,
+                                               queue,
+                                               factory
+                );
+            }
+            else
+            {
+                return new ThreadPoolExecutor( metaInfo.coreThreads,
+                                               metaInfo.maxThreads,
+                                               metaInfo.time,
+                                               metaInfo.unit,
+                                               queue,
+                                               factory,
+                                               metaInfo.rejectedExecutionHandler
+                );
+            }
+        }
+
+        @Override
+        public boolean isAvailable( Object instance )
+        {
+            return false;
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ScheduledExecutionServiceAssembler.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ScheduledExecutionServiceAssembler.java b/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ScheduledExecutionServiceAssembler.java
new file mode 100644
index 0000000..c76d2b0
--- /dev/null
+++ b/libraries/execution/src/main/java/org/apache/polygene/library/execution/assembly/ScheduledExecutionServiceAssembler.java
@@ -0,0 +1,140 @@
+package org.apache.polygene.library.execution.assembly;
+
+import java.util.concurrent.RejectedExecutionHandler;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
+import java.util.concurrent.ThreadFactory;
+import org.apache.polygene.api.service.ImportedServiceDescriptor;
+import org.apache.polygene.api.service.ServiceImporter;
+import org.apache.polygene.api.service.ServiceImporterException;
+import org.apache.polygene.bootstrap.Assembler;
+import org.apache.polygene.bootstrap.Assemblers;
+import org.apache.polygene.bootstrap.AssemblyException;
+import org.apache.polygene.bootstrap.ModuleAssembly;
+
+public class ScheduledExecutionServiceAssembler extends Assemblers.VisibilityIdentityConfig<ScheduledExecutionServiceAssembler>
+    implements Assembler
+{
+
+    private ThreadFactory factory;
+    private RejectedExecutionHandler rejectedExecutionHandler;
+    private int coreThreads = 3;
+    private ThreadGroup group;
+
+    @Override
+    public void assemble( ModuleAssembly module )
+        throws AssemblyException
+    {
+        module.importedServices( ScheduledExecutorService.class )
+              .importedBy( ThreadPoolExecutorImporter.class )
+              .setMetaInfo( this )
+        ;
+    }
+
+    /**
+     * Number of core threads, i.e. threads that are not removed if idle, to be used.
+     *
+     * @param threads core threads to use
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Number of core threads, i.e. threads that are not removed if idle, to be used.
+    public ScheduledExecutionServiceAssembler withCoreThreads( int threads )
+    // END SNIPPET: configuration
+    {
+        this.coreThreads = threads;
+        return this;
+    }
+
+    /**
+     * Provide a custom ThreadFactory.
+     * <p>
+     * If defined, the {@link #inThreadGroup(ThreadGroup)} parameter will be ignored.
+     * </p>
+     *
+     * @param factory The thread factory to use, when creating threads.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Provide a custom ThreadFactory. If defined, the inThreadGroup parameter will be ignored.
+    public ScheduledExecutionServiceAssembler withThreadFactory( ThreadFactory factory )
+    // END SNIPPET: configuration
+    {
+        this.factory = factory;
+        return this;
+    }
+
+    /**
+     * Provide a custom {@link RejectedExecutionHandler}, or one of the pre-defined policies
+     *
+     * @param handler the custom {@link RejectedExecutionHandler} to use.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Provide a custom RejectedExecutionHandler, or one of the pre-defined policies
+    public ScheduledExecutionServiceAssembler withRejectedExecutionHandler( RejectedExecutionHandler handler )
+    // END SNIPPET: configuration
+    {
+        this.rejectedExecutionHandler = handler;
+        return this;
+    }
+
+    /**
+     * Thread Group to create the threads in.
+     * <p>
+     * If a custom ThreadFactory is given, {@link #withThreadFactory(ThreadFactory)} then this parameter is ignored.
+     * </p>
+     *
+     * @param group The thread group that all threads should be placed in.
+     * @return Fluent API
+     */
+    // START SNIPPET: configuration
+    // Thread Group to create the threads in
+    public ScheduledExecutionServiceAssembler inThreadGroup( ThreadGroup group )
+    // END SNIPPET: configuration
+    {
+        this.group = group;
+        return this;
+    }
+
+    private static class ThreadPoolExecutorImporter
+        implements ServiceImporter
+    {
+        long count = 0;
+
+        @Override
+        public Object importService( ImportedServiceDescriptor serviceDescriptor )
+            throws ServiceImporterException
+        {
+            ScheduledExecutionServiceAssembler metaInfo = serviceDescriptor.metaInfo( ScheduledExecutionServiceAssembler.class );
+            ThreadGroup group;
+            if( metaInfo.group == null )
+            {
+                group = new ThreadGroup( "tg-" + metaInfo.identity() );
+            }
+            else
+            {
+                group = metaInfo.group;
+            }
+            ThreadFactory factory = metaInfo.factory;
+            if( factory == null )
+            {
+                factory = runnable -> new Thread( group, runnable, "t-" + count++ );
+            }
+            if( metaInfo.rejectedExecutionHandler == null )
+            {
+                return new ScheduledThreadPoolExecutor( metaInfo.coreThreads, factory );
+            }
+            else
+            {
+                return new ScheduledThreadPoolExecutor( metaInfo.coreThreads, factory, metaInfo.rejectedExecutionHandler );
+            }
+        }
+
+        @Override
+        public boolean isAvailable( Object instance )
+        {
+            return false;
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/test/java/org/apache/polygene/library/execution/ExecutionServiceTest.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/test/java/org/apache/polygene/library/execution/ExecutionServiceTest.java b/libraries/execution/src/test/java/org/apache/polygene/library/execution/ExecutionServiceTest.java
new file mode 100644
index 0000000..d39cc26
--- /dev/null
+++ b/libraries/execution/src/test/java/org/apache/polygene/library/execution/ExecutionServiceTest.java
@@ -0,0 +1,51 @@
+package org.apache.polygene.library.execution;
+
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.ExecutorService;
+import org.apache.polygene.bootstrap.AssemblyException;
+import org.apache.polygene.bootstrap.ModuleAssembly;
+import org.apache.polygene.library.execution.assembly.ExecutionServiceAssembler;
+import org.apache.polygene.test.AbstractPolygeneTest;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.IsEqual.equalTo;
+
+public class ExecutionServiceTest extends AbstractPolygeneTest
+{
+
+    private CopyOnWriteArraySet<Thread> threads = new CopyOnWriteArraySet<>();
+
+    @Override
+    public void assemble( ModuleAssembly module )
+        throws AssemblyException
+    {
+        new ExecutionServiceAssembler()
+            .withMaxThreads( 3 )
+            .assemble( module );
+    }
+
+    @Test
+    void givenMaxThreeThreadsWhenSubmittingManyTasksExpectToOnlySeeThreeThreads()
+        throws InterruptedException
+    {
+        ExecutorService underTest = serviceFinder.findService( ExecutorService.class ).get();
+        Runnable r = () -> {
+            threads.add( Thread.currentThread() );
+        };
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        underTest.submit( r );
+        Thread.sleep( 10 );
+        assertThat( threads.size(), equalTo( 3 ) );
+        underTest.shutdownNow();
+    }
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/test/java/org/apache/polygene/library/execution/RetryTest.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/test/java/org/apache/polygene/library/execution/RetryTest.java b/libraries/execution/src/test/java/org/apache/polygene/library/execution/RetryTest.java
new file mode 100644
index 0000000..4ed6086
--- /dev/null
+++ b/libraries/execution/src/test/java/org/apache/polygene/library/execution/RetryTest.java
@@ -0,0 +1,184 @@
+package org.apache.polygene.library.execution;
+
+import org.apache.polygene.api.mixin.Mixins;
+import org.apache.polygene.bootstrap.AssemblyException;
+import org.apache.polygene.bootstrap.ModuleAssembly;
+import org.apache.polygene.test.AbstractPolygeneTest;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.greaterThan;
+import static org.hamcrest.Matchers.greaterThanOrEqualTo;
+import static org.hamcrest.Matchers.lessThan;
+import static org.hamcrest.core.IsEqual.equalTo;
+
+// TODO: These tests are extremely slow. Why is that? Could it be the streaming of exception class hierarchies?
+public class RetryTest extends AbstractPolygeneTest
+{
+    @Override
+    public void assemble( ModuleAssembly module )
+        throws AssemblyException
+    {
+        module.services( TestService.class ).withConcerns( RetryConcern.class ).instantiateOnStartup();
+    }
+
+    @Test
+    void givenMethodThrowingExceptionWhenCallingExpectFourCalls()
+    {
+        TestService underTest = serviceFinder.findService( TestService.class ).get();
+        long start = System.currentTimeMillis();
+        try
+        {
+            underTest.doWithRetry1();
+        }
+        catch( IllegalStateException e )
+        {
+            // expected after 4 calls
+        }
+        long end = System.currentTimeMillis();
+        assertThat( underTest.calledTimes(), equalTo(4));
+        assertThat( end-start, lessThan(20L));
+    }
+
+    @Test
+    void givenMethodThrowingExceptionWhenCallingExpectFiveCalls()
+    {
+        TestService underTest = serviceFinder.findService( TestService.class ).get();
+        long start = System.currentTimeMillis();
+        try
+        {
+            underTest.doWithRetry2();
+        }
+        catch( IllegalStateException e )
+        {
+            // expected after 4 calls
+        }
+        long end = System.currentTimeMillis();
+        assertThat( underTest.calledTimes(), equalTo(5));
+        assertThat( end-start, lessThan(20L));
+    }
+
+    @Test
+    void givenMethodThrowingExceptionWhenCallingExpectSixCalls()
+    {
+        TestService underTest = serviceFinder.findService( TestService.class ).get();
+        long start = System.currentTimeMillis();
+        try
+        {
+            underTest.doWithRetry3();
+        }
+        catch( IllegalStateException e )
+        {
+            // expected after 4 calls
+        }
+        long end = System.currentTimeMillis();
+        assertThat( underTest.calledTimes(), equalTo(6));
+        assertThat( end-start, lessThan(20L));
+    }
+
+    @Test
+    void givenMethodThrowingExceptionWhenCallingExpectOneTries()
+    {
+        TestService underTest = serviceFinder.findService( TestService.class ).get();
+        long start = System.currentTimeMillis();
+        try
+        {
+            underTest.doWithRetry4();
+        }
+        catch( IllegalStateException e )
+        {
+            // expected after 1 calls, since IllegalStateException is an "unless"
+        }
+        long end = System.currentTimeMillis();
+        assertThat( underTest.calledTimes(), equalTo(1));
+        assertThat( end-start, lessThan(20L));
+    }
+
+    @Test
+    void givenBackoffExceptionWhenCallingExpectSlowTries()
+    {
+        TestService underTest = serviceFinder.findService( TestService.class ).get();
+        long start = System.currentTimeMillis();
+        try
+        {
+            underTest.doWithRetry5();
+        }
+        catch( IllegalStateException e )
+        {
+            // expected after 1 calls, since IllegalStateException is an "unless"
+        }
+        long end = System.currentTimeMillis();
+        assertThat( underTest.calledTimes(), equalTo(3));
+        assertThat( end-start, greaterThanOrEqualTo( 300L));
+    }
+
+
+    @Mixins( TestMixin.class)
+    public interface TestService{
+
+        int calledTimes();
+
+        @Retry(4)
+        void doWithRetry1();
+
+        @Retry( value=5, on = IllegalStateException.class )
+        void doWithRetry2();
+
+        @Retry( value=6, on = IllegalStateException.class )
+        void doWithRetry3();
+
+        @Retry( value=7, unless = IllegalStateException.class )
+        void doWithRetry4();
+
+        @Retry( value = 3, backoff = 100 )
+        void doWithRetry5();
+    }
+
+    public class TestMixin
+        implements TestService
+    {
+
+        private int called = 0;
+
+        @Override
+        public int calledTimes()
+        {
+            return called;
+        }
+
+        @Override
+        public void doWithRetry1()
+        {
+            called++;
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public void doWithRetry2()
+        {
+            called++;
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public void doWithRetry3()
+        {
+            called++;
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public void doWithRetry4()
+        {
+            called++;
+            throw new IllegalStateException();
+        }
+
+        @Override
+        public void doWithRetry5()
+        {
+            called++;
+            throw new IllegalStateException();
+        }
+    }
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/libraries/execution/src/test/java/org/apache/polygene/library/execution/ScheduledExecutionServiceTest.java
----------------------------------------------------------------------
diff --git a/libraries/execution/src/test/java/org/apache/polygene/library/execution/ScheduledExecutionServiceTest.java b/libraries/execution/src/test/java/org/apache/polygene/library/execution/ScheduledExecutionServiceTest.java
new file mode 100644
index 0000000..83c9e12
--- /dev/null
+++ b/libraries/execution/src/test/java/org/apache/polygene/library/execution/ScheduledExecutionServiceTest.java
@@ -0,0 +1,46 @@
+package org.apache.polygene.library.execution;
+
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.apache.polygene.bootstrap.AssemblyException;
+import org.apache.polygene.bootstrap.ModuleAssembly;
+import org.apache.polygene.library.execution.assembly.ExecutionServiceAssembler;
+import org.apache.polygene.library.execution.assembly.ScheduledExecutionServiceAssembler;
+import org.apache.polygene.test.AbstractPolygeneTest;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.core.IsEqual.equalTo;
+
+public class ScheduledExecutionServiceTest extends AbstractPolygeneTest
+{
+
+    private volatile AtomicInteger executed = new AtomicInteger( 0 );
+
+    @Override
+    public void assemble( ModuleAssembly module )
+        throws AssemblyException
+    {
+        new ScheduledExecutionServiceAssembler()
+            .assemble( module );
+    }
+
+    @Test
+    void givenScheduleOfTenMillisWhenSubmittingTwoTasksFor105MillisExpect20Invocations()
+        throws InterruptedException
+    {
+        ScheduledExecutorService underTest = serviceFinder.findService( ScheduledExecutorService.class ).get();
+        Runnable r = () -> {
+            executed.incrementAndGet();
+        };
+        underTest.scheduleAtFixedRate( r, 10, 10, TimeUnit.MILLISECONDS );
+        underTest.scheduleAtFixedRate( r, 10, 10, TimeUnit.MILLISECONDS );
+        Thread.sleep( 105 );
+        assertThat( executed.intValue(), equalTo( 20 ) );
+        underTest.shutdownNow();
+    }
+
+}

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/manual/src/docs/userguide/libraries.txt
----------------------------------------------------------------------
diff --git a/manual/src/docs/userguide/libraries.txt b/manual/src/docs/userguide/libraries.txt
index b4bcce6..c07445c 100644
--- a/manual/src/docs/userguide/libraries.txt
+++ b/manual/src/docs/userguide/libraries.txt
@@ -47,6 +47,10 @@ include::../../../../libraries/constraints/src/docs/constraints.txt[]
 
 :leveloffset: 2
 
+include::../../../../libraries/execution/src/docs/execution.txt[]
+
+:leveloffset: 2
+
 include::../../../../libraries/fileconfig/src/docs/fileconfig.txt[]
 
 :leveloffset: 2

http://git-wip-us.apache.org/repos/asf/polygene-java/blob/db99803f/settings.gradle
----------------------------------------------------------------------
diff --git a/settings.gradle b/settings.gradle
index 0f503e1..c0b9ed3 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -28,6 +28,7 @@ include 'core:api',
         'libraries:alarm',
         'libraries:circuitbreaker',
         'libraries:constraints',
+        'libraries:execution',
         'libraries:fileconfig',
         'libraries:http',
         'libraries:invocation-cache',