Implemented asynchronous decision engine. Resolved #210

dmn-engine/src/main/java/org/powerflows/dmn/engine/AsyncDecisionEngine.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
+ *
+ * Licensed 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.
+ */
+
+package org.powerflows.dmn.engine;
+
+
+import org.powerflows.dmn.engine.model.decision.Decision;
+import org.powerflows.dmn.engine.model.evaluation.result.DecisionResult;
+import org.powerflows.dmn.engine.model.evaluation.variable.DecisionVariables;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * AsynchronousdDecision engine contract.
+ */
+public interface AsyncDecisionEngine {
+
+    /**
+     * @param decision          Definition of decision
+     * @param decisionVariables Variables used in evaluation
+     * @return a promise of evaluation result
+     */
+    CompletableFuture<DecisionResult> evaluate(Decision decision, DecisionVariables decisionVariables);
+
+}

dmn-engine/src/main/java/org/powerflows/dmn/engine/DefaultAsyncDecisionEngine.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
+ *
+ * Licensed 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.
+ */
+package org.powerflows.dmn.engine;
+
+import org.powerflows.dmn.engine.model.decision.Decision;
+import org.powerflows.dmn.engine.model.evaluation.result.DecisionResult;
+import org.powerflows.dmn.engine.model.evaluation.variable.DecisionVariables;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+
+/**
+ * Default asynchronous decision engine implementation.
+ */
+public class DefaultAsyncDecisionEngine implements AsyncDecisionEngine {
+    private static final Logger LOG = LoggerFactory.getLogger(DefaultAsyncDecisionEngine.class);
+    private final DecisionEngine decisionEngine;
+    private final ExecutorService executorService;
+
+    public DefaultAsyncDecisionEngine(DecisionEngine decisionEngine, ExecutorService executorService) {
+        this.decisionEngine = decisionEngine;
+        this.executorService = executorService;
+    }
+
+    @Override
+    public CompletableFuture<DecisionResult> evaluate(final Decision decision, final DecisionVariables decisionVariables) {
+        final CompletableFuture<DecisionResult> result = new CompletableFuture<>();
+        executorService.submit(() -> {
+            try {
+                result.complete(decisionEngine.evaluate(decision, decisionVariables));
+            } catch (Exception e) {
+                LOG.debug("Error completing decision evaluation", e);
+                result.completeExceptionally(e);
+            }
+        });
+
+        return result;
+    }
+}

dmn-engine/src/main/java/org/powerflows/dmn/engine/configuration/AsyncDecisionEngineConfiguration.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
+ *
+ * Licensed 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.
+ */
+
+package org.powerflows.dmn.engine.configuration;
+
+
+import org.powerflows.dmn.engine.AsyncDecisionEngine;
+
+/**
+ * Interface for AsyncDecisionEngine configurers.
+ *
+ * @see DefaultAsyncDecisionEngineConfiguration
+ */
+public interface AsyncDecisionEngineConfiguration {
+
+    /**
+     * Create ready to use decision engine.
+     *
+     * @return AsyncDecisionEngine instance
+     */
+    AsyncDecisionEngine configure();
+
+}

dmn-engine/src/main/java/org/powerflows/dmn/engine/configuration/DecisionEngineConfiguration.java

@@ -18,12 +18,16 @@
 
 
 import org.powerflows.dmn.engine.DecisionEngine;
+import org.powerflows.dmn.engine.evaluator.expression.provider.binding.MethodBinding;
+
+import java.util.List;
 
 /**
  * Interface for DecisionEngine configurers.
+ *
  * @see DefaultDecisionEngineConfiguration
  */
-public interface DecisionEngineConfiguration {
+public interface DecisionEngineConfiguration<T extends DecisionEngineConfiguration> {
 
     /**
      * Create ready to use decision engine.
@@ -32,4 +36,5 @@ public interface DecisionEngineConfiguration {
      */
     DecisionEngine configure();
 
+    T methodBindings(List<MethodBinding> methodBindings);
 }

dmn-engine/src/main/java/org/powerflows/dmn/engine/configuration/DefaultAsyncDecisionEngineConfiguration.java

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
+ *
+ * Licensed 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.
+ */
+package org.powerflows.dmn.engine.configuration;
+
+import lombok.Setter;
+import lombok.experimental.Accessors;
+import org.powerflows.dmn.engine.AsyncDecisionEngine;
+import org.powerflows.dmn.engine.DefaultAsyncDecisionEngine;
+import org.powerflows.dmn.engine.evaluator.expression.provider.binding.MethodBinding;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+/**
+ * Default DecisionEngine configurer.
+ * Builds and configures {@link DefaultAsyncDecisionEngine} instances.
+ * Allows for customisation of method binding configuration.
+ * Uses single thread asynchronous executor service by default @see Executors.newSingleThreadExecutor
+ *
+ * @see MethodBinding
+ */
+@Accessors(chain = true, fluent = true)
+public class DefaultAsyncDecisionEngineConfiguration implements AsyncDecisionEngineConfiguration {
+    @Setter
+    private DecisionEngineConfiguration engineConfiguration;
+    @Setter
+    private ExecutorService executorService;
+    @Setter
+    private List<MethodBinding> methodBindings = Collections.emptyList();
+
+    @Override
+    public AsyncDecisionEngine configure() {
+        initEngineConfiguration();
+        initMethodBindings();
+        initExecutorService();
+
+        return new DefaultAsyncDecisionEngine(engineConfiguration.configure(), executorService);
+    }
+
+    private void initMethodBindings() {
+        engineConfiguration.methodBindings(methodBindings);
+    }
+
+    private void initEngineConfiguration() {
+        if (engineConfiguration == null) {
+            engineConfiguration = new DefaultDecisionEngineConfiguration();
+        }
+    }
+
+    private void initExecutorService() {
+        if (executorService == null) {
+            executorService = Executors.newSingleThreadExecutor();
+        }
+    }
+}

dmn-engine/src/main/java/org/powerflows/dmn/engine/configuration/DefaultDecisionEngineConfiguration.java

@@ -42,7 +42,7 @@
  * @see MethodBinding
  */
 @Accessors(chain = true, fluent = true)
-public class DefaultDecisionEngineConfiguration implements DecisionEngineConfiguration {
+public class DefaultDecisionEngineConfiguration implements DecisionEngineConfiguration<DefaultDecisionEngineConfiguration> {
 
     @Setter
     private List<MethodBinding> methodBindings = Collections.emptyList();

dmn-engine/src/test/groovy/org/powerflows/dmn/engine/configuration/DefaultAsyncDecisionEngineConfigurationSpec.groovy

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2018-present PowerFlows.org - all rights reserved.
+ *
+ * Licensed 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.
+ */
+
+package org.powerflows.dmn.engine.configuration
+
+import org.powerflows.dmn.engine.AsyncDecisionEngine
+import org.powerflows.dmn.engine.DecisionEngine
+import org.powerflows.dmn.engine.model.decision.Decision
+import org.powerflows.dmn.engine.model.evaluation.result.DecisionResult
+import org.powerflows.dmn.engine.model.evaluation.variable.DecisionVariables
+import spock.lang.Shared
+import spock.lang.Specification
+
+import java.util.concurrent.CompletableFuture
+
+class DefaultAsyncDecisionEngineConfigurationSpec extends Specification {
+
+    @Shared
+    private AsyncDecisionEngineConfiguration asyncDecisionEngineConfiguration
+
+    @Shared
+    private DecisionEngineConfiguration decisionEngineConfiguration
+
+    @Shared
+    private DecisionEngine decisionEngine
+
+    @Shared
+    private DecisionResult decisionResult
+
+    @Shared
+    private Decision decision
+
+    void setupSpec() {
+        decisionResult = Mock()
+        decisionEngine = Mock() {
+            evaluate(_, _) >> decisionResult
+        }
+        decisionEngineConfiguration = Mock() {
+            configure() >>
+                    decisionEngine
+
+        }
+        asyncDecisionEngineConfiguration = new DefaultAsyncDecisionEngineConfiguration(
+                engineConfiguration: decisionEngineConfiguration
+        )
+
+        decision = Mock()
+    }
+
+    void 'should evaluate asynchronously'() {
+        given:
+        final DecisionVariables decisionVariables = new DecisionVariables([:])
+
+        when:
+        final AsyncDecisionEngine asyncDecisionEngine = asyncDecisionEngineConfiguration.configure()
+
+        then:
+        asyncDecisionEngine != null
+
+        when:
+        final CompletableFuture<DecisionResult> future = asyncDecisionEngine.evaluate(decision, decisionVariables)
+
+        then:
+        future != null
+        DecisionResult result = future.get()
+        result != null
+
+        0 * _
+    }
+}