2 * ============LICENSE_START=======================================================
3 * Copyright (C) 2016-2018 Ericsson. All rights reserved.
4 * ================================================================================
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
17 * SPDX-License-Identifier: Apache-2.0
18 * ============LICENSE_END=========================================================
21 package org.onap.policy.apex.core.engine.engine.impl;
23 import java.util.HashMap;
25 import org.onap.policy.apex.core.engine.context.ApexInternalContext;
26 import org.onap.policy.apex.core.engine.event.EnEvent;
27 import org.onap.policy.apex.core.engine.executor.ExecutorFactory;
28 import org.onap.policy.apex.core.engine.executor.StateMachineExecutor;
29 import org.onap.policy.apex.core.engine.executor.exception.StateMachineException;
30 import org.onap.policy.apex.core.engine.executor.impl.ExecutorFactoryImpl;
31 import org.onap.policy.apex.model.basicmodel.concepts.AxArtifactKey;
32 import org.onap.policy.apex.model.basicmodel.service.ModelService;
33 import org.onap.policy.apex.model.eventmodel.concepts.AxEvent;
34 import org.onap.policy.apex.model.eventmodel.concepts.AxEvents;
35 import org.onap.policy.apex.model.policymodel.concepts.AxPolicies;
36 import org.onap.policy.apex.model.policymodel.concepts.AxPolicy;
37 import org.slf4j.ext.XLogger;
38 import org.slf4j.ext.XLoggerFactory;
41 * This handler holds and manages state machines for each policy in an Apex engine. When the class is instantiated, an
42 * executor {@link StateMachineExecutor} is created for each policy in the policy model the state machine handler will
43 * execute. The executors for each policy are held in a map indexed by event.
45 * <p>When an event is received on the policy, the state machine executor to execute that event is looked up on the
46 * executor map and the event is passed to the executor for execution.
51 public class StateMachineHandler {
52 // Logger for this class
53 private static final XLogger LOGGER = XLoggerFactory.getXLogger(StateMachineHandler.class);
55 // The key of the Apex model we are executing
56 private final AxArtifactKey key;
58 // The state machines in this engine
59 private final HashMap<AxEvent, StateMachineExecutor> stateMachineExecutorMap = new HashMap<>();
61 // The executor factory is used to get logic executors for the particular type of executor we
63 // selection logic or task logic
64 private final ExecutorFactory executorFactory;
67 * This constructor builds the state machines for the policies in the apex model.
69 * @param internalContext The internal context we are using
70 * @throws StateMachineException On state machine initiation errors
72 protected StateMachineHandler(final ApexInternalContext internalContext) throws StateMachineException {
73 LOGGER.entry("StateMachineHandler()->" + internalContext.getKey().getId());
75 key = internalContext.getKey();
77 // Create the executor factory to generate executors as the engine runs policies
78 executorFactory = new ExecutorFactoryImpl();
80 // Iterate over the policies in the policy model and create a state machine for each one
81 for (final AxPolicy policy : ModelService.getModel(AxPolicies.class).getPolicyMap().values()) {
82 // Create a state machine for this policy
83 final StateMachineExecutor thisStateMachineExecutor =
84 new StateMachineExecutor(executorFactory, policy.getKey());
86 // This executor is the top executor so has no parent
87 thisStateMachineExecutor.setContext(null, policy, internalContext);
89 // Get the incoming trigger event
90 final AxEvent triggerEvent = ModelService.getModel(AxEvents.class)
91 .get(policy.getStateMap().get(policy.getFirstState()).getTrigger());
93 // Put the state machine executor on the map for this trigger
94 final StateMachineExecutor lastStateMachineExecutor =
95 stateMachineExecutorMap.put(triggerEvent, thisStateMachineExecutor);
96 if (lastStateMachineExecutor != null
97 && lastStateMachineExecutor.getSubject() != thisStateMachineExecutor.getSubject()) {
98 LOGGER.error("No more than one policy in a model can have the same trigger event. In model "
99 + internalContext.getKey().getId() + " Policy ("
100 + lastStateMachineExecutor.getSubject().getKey().getId() + ") and Policy ("
101 + thisStateMachineExecutor.getSubject().getKey().getId() + ") have the same Trigger event ("
102 + triggerEvent.getKey().getId() + ") ");
103 LOGGER.error(" Policy (" + lastStateMachineExecutor.getSubject().getKey() + ") has overwritten Policy ("
104 + thisStateMachineExecutor.getSubject().getKey().getId()
105 + " so this overwritten policy will never be triggered in this engine.");
109 LOGGER.exit("StateMachineHandler()<-" + internalContext.getKey().getId());
113 * This constructor starts the state machines for each policy, carrying out whatever initialization executors need.
115 * @throws StateMachineException On state machine initiation errors
117 protected void start() throws StateMachineException {
118 LOGGER.entry("start()->" + key.getId());
120 // Iterate over the state machines
121 for (final StateMachineExecutor smExecutor : stateMachineExecutorMap.values()) {
123 smExecutor.prepare();
124 } catch (final StateMachineException e) {
125 final String stateMachineId = smExecutor.getContext().getKey().getId();
126 String message = "start()<-" + key.getId() + ", start failed, state machine \"" + stateMachineId + "\"";
127 LOGGER.warn(message, e);
128 throw new StateMachineException(message, e);
132 LOGGER.exit("start()<-" + key.getId());
136 * This method is called to execute an event on the state machines in an engine.
138 * @param event The trigger event for the state machine
139 * @return The result of the state machine execution run
140 * @throws StateMachineException On execution errors in a state machine
142 protected EnEvent execute(final EnEvent event) throws StateMachineException {
143 LOGGER.entry("execute()->" + event.getName());
145 // Try to execute the state machine for the trigger
146 final StateMachineExecutor stateMachineExecutor = stateMachineExecutorMap.get(event.getAxEvent());
147 if (stateMachineExecutor == null) {
148 final String exceptionMessage =
149 "state machine execution not possible, policy not found for trigger event " + event.getName();
150 LOGGER.warn(exceptionMessage);
152 event.setExceptionMessage(exceptionMessage);
156 // Run the state machine
158 LOGGER.debug("execute(): state machine \"{}\" execution starting . . .", stateMachineExecutor);
159 final EnEvent outputObject =
160 stateMachineExecutor.execute(event.getExecutionId(), event.getExecutionProperties(), event);
162 LOGGER.debug("execute()<-: state machine \"{}\" execution completed", stateMachineExecutor);
164 } catch (final Exception e) {
165 LOGGER.warn("execute()<-: state machine \"" + stateMachineExecutor + "\" execution failed", e);
166 throw new StateMachineException("execute()<-: execution failed on state machine " + stateMachineExecutor,
172 * Closes down the state machines of an engine.
174 protected void stop() {
175 LOGGER.entry("stop()->");
177 // Iterate through all state machines and clean them
178 for (final StateMachineExecutor smExecutor : stateMachineExecutorMap.values()) {
180 smExecutor.cleanUp();
181 } catch (final StateMachineException e) {
182 final String smId = smExecutor.getContext().getKey().getId();
183 LOGGER.warn("stop()<-clean up failed, state machine \"" + smId + "\" cleanup failed", e);
186 LOGGER.exit("stop()<-");