| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.springframework.batch.core.job.flow.support; |
| 17 | |
| 18 | import java.util.ArrayList; |
| 19 | import java.util.Collection; |
| 20 | import java.util.HashMap; |
| 21 | import java.util.HashSet; |
| 22 | import java.util.List; |
| 23 | import java.util.Map; |
| 24 | import java.util.Set; |
| 25 | import java.util.SortedSet; |
| 26 | import java.util.TreeSet; |
| 27 | |
| 28 | import org.apache.commons.logging.Log; |
| 29 | import org.apache.commons.logging.LogFactory; |
| 30 | import org.springframework.batch.core.JobExecutionException; |
| 31 | import org.springframework.batch.core.Step; |
| 32 | import org.springframework.batch.core.job.flow.Flow; |
| 33 | import org.springframework.batch.core.job.flow.FlowExecution; |
| 34 | import org.springframework.batch.core.job.flow.FlowExecutionException; |
| 35 | import org.springframework.batch.core.job.flow.FlowExecutionStatus; |
| 36 | import org.springframework.batch.core.job.flow.FlowExecutor; |
| 37 | import org.springframework.batch.core.job.flow.State; |
| 38 | import org.springframework.beans.factory.InitializingBean; |
| 39 | |
| 40 | /** |
| 41 | * A {@link Flow} that branches conditionally depending on the exit status of |
| 42 | * the last {@link State}. The input parameters are the state transitions (in no |
| 43 | * particular order). The start state name can be specified explicitly (and must |
| 44 | * exist in the set of transitions), or computed from the existing transitions, |
| 45 | * if unambiguous. |
| 46 | * |
| 47 | * @author Dave Syer |
| 48 | * @since 2.0 |
| 49 | */ |
| 50 | public class SimpleFlow implements Flow, InitializingBean { |
| 51 | |
| 52 | private static final Log logger = LogFactory.getLog(SimpleFlow.class); |
| 53 | |
| 54 | private State startState; |
| 55 | |
| 56 | private Map<String, SortedSet<StateTransition>> transitionMap = new HashMap<String, SortedSet<StateTransition>>(); |
| 57 | |
| 58 | private Map<String, State> stateMap = new HashMap<String, State>(); |
| 59 | |
| 60 | private List<StateTransition> stateTransitions = new ArrayList<StateTransition>(); |
| 61 | |
| 62 | private final String name; |
| 63 | |
| 64 | /** |
| 65 | * Create a flow with the given name. |
| 66 | * |
| 67 | * @param name the name of the flow |
| 68 | */ |
| 69 | public SimpleFlow(String name) { |
| 70 | this.name = name; |
| 71 | } |
| 72 | |
| 73 | /** |
| 74 | * Get the name for this flow. |
| 75 | * |
| 76 | * @see Flow#getName() |
| 77 | */ |
| 78 | public String getName() { |
| 79 | return name; |
| 80 | } |
| 81 | |
| 82 | /** |
| 83 | * Public setter for the stateTransitions. |
| 84 | * |
| 85 | * @param stateTransitions the stateTransitions to set |
| 86 | */ |
| 87 | public void setStateTransitions(List<StateTransition> stateTransitions) { |
| 88 | |
| 89 | this.stateTransitions = stateTransitions; |
| 90 | } |
| 91 | |
| 92 | /** |
| 93 | * {@inheritDoc} |
| 94 | */ |
| 95 | public State getState(String stateName) { |
| 96 | return stateMap.get(stateName); |
| 97 | } |
| 98 | |
| 99 | /** |
| 100 | * {@inheritDoc} |
| 101 | */ |
| 102 | public Collection<State> getStates() { |
| 103 | return new HashSet<State>(stateMap.values()); |
| 104 | } |
| 105 | |
| 106 | /** |
| 107 | * Locate start state and pre-populate data structures needed for execution. |
| 108 | * |
| 109 | * @see InitializingBean#afterPropertiesSet() |
| 110 | */ |
| 111 | public void afterPropertiesSet() throws Exception { |
| 112 | initializeTransitions(); |
| 113 | } |
| 114 | |
| 115 | /** |
| 116 | * @see Flow#start(FlowExecutor) |
| 117 | */ |
| 118 | public FlowExecution start(FlowExecutor executor) throws FlowExecutionException { |
| 119 | if (startState == null) { |
| 120 | initializeTransitions(); |
| 121 | } |
| 122 | State state = startState; |
| 123 | String stateName = state.getName(); |
| 124 | return resume(stateName, executor); |
| 125 | } |
| 126 | |
| 127 | /** |
| 128 | * @see Flow#resume(String, FlowExecutor) |
| 129 | */ |
| 130 | public FlowExecution resume(String stateName, FlowExecutor executor) throws FlowExecutionException { |
| 131 | |
| 132 | FlowExecutionStatus status = FlowExecutionStatus.UNKNOWN; |
| 133 | State state = stateMap.get(stateName); |
| 134 | |
| 135 | logger.debug("Resuming state="+stateName+" with status="+status); |
| 136 | |
| 137 | // Terminate if there are no more states |
| 138 | while (state != null && status!=FlowExecutionStatus.STOPPED) { |
| 139 | |
| 140 | stateName = state.getName(); |
| 141 | |
| 142 | try { |
| 143 | logger.debug("Handling state="+stateName); |
| 144 | status = state.handle(executor); |
| 145 | } |
| 146 | catch (FlowExecutionException e) { |
| 147 | executor.close(new FlowExecution(stateName, status)); |
| 148 | throw e; |
| 149 | } |
| 150 | catch (Exception e) { |
| 151 | executor.close(new FlowExecution(stateName, status)); |
| 152 | throw new FlowExecutionException(String.format("Ended flow=%s at state=%s with exception", name, |
| 153 | stateName), e); |
| 154 | } |
| 155 | |
| 156 | logger.debug("Completed state="+stateName+" with status="+status); |
| 157 | |
| 158 | state = nextState(stateName, status); |
| 159 | |
| 160 | } |
| 161 | |
| 162 | FlowExecution result = new FlowExecution(stateName, status); |
| 163 | executor.close(result); |
| 164 | return result; |
| 165 | |
| 166 | } |
| 167 | |
| 168 | /** |
| 169 | * @return the next {@link Step} (or null if this is the end) |
| 170 | * @throws JobExecutionException |
| 171 | */ |
| 172 | private State nextState(String stateName, FlowExecutionStatus status) throws FlowExecutionException { |
| 173 | |
| 174 | Set<StateTransition> set = transitionMap.get(stateName); |
| 175 | |
| 176 | if (set == null) { |
| 177 | throw new FlowExecutionException(String.format("No transitions found in flow=%s for state=%s", getName(), |
| 178 | stateName)); |
| 179 | } |
| 180 | |
| 181 | String next = null; |
| 182 | String exitCode = status.getName(); |
| 183 | for (StateTransition stateTransition : set) { |
| 184 | if (stateTransition.matches(exitCode)) { |
| 185 | if (stateTransition.isEnd()) { |
| 186 | // End of job |
| 187 | return null; |
| 188 | } |
| 189 | next = stateTransition.getNext(); |
| 190 | break; |
| 191 | } |
| 192 | } |
| 193 | |
| 194 | if (next == null) { |
| 195 | throw new FlowExecutionException(String.format( |
| 196 | "Next state not found in flow=%s for state=%s with exit status=%s", getName(), stateName, status.getName())); |
| 197 | } |
| 198 | |
| 199 | if (!stateMap.containsKey(next)) { |
| 200 | throw new FlowExecutionException(String.format("Next state not specified in flow=%s for next=%s", |
| 201 | getName(), next)); |
| 202 | } |
| 203 | |
| 204 | return stateMap.get(next); |
| 205 | |
| 206 | } |
| 207 | |
| 208 | /** |
| 209 | * Analyse the transitions provided and generate all the information needed |
| 210 | * to execute the flow. |
| 211 | */ |
| 212 | private void initializeTransitions() { |
| 213 | startState = null; |
| 214 | transitionMap.clear(); |
| 215 | stateMap.clear(); |
| 216 | boolean hasEndStep = false; |
| 217 | |
| 218 | if (stateTransitions.isEmpty()) { |
| 219 | throw new IllegalArgumentException("No start state was found. You must specify at least one step in a job."); |
| 220 | } |
| 221 | |
| 222 | for (StateTransition stateTransition : stateTransitions) { |
| 223 | State state = stateTransition.getState(); |
| 224 | stateMap.put(state.getName(), state); |
| 225 | } |
| 226 | |
| 227 | for (StateTransition stateTransition : stateTransitions) { |
| 228 | |
| 229 | State state = stateTransition.getState(); |
| 230 | |
| 231 | if (!stateTransition.isEnd()) { |
| 232 | |
| 233 | String next = stateTransition.getNext(); |
| 234 | |
| 235 | if (!stateMap.containsKey(next)) { |
| 236 | throw new IllegalArgumentException("Missing state for [" + stateTransition + "]"); |
| 237 | } |
| 238 | |
| 239 | } |
| 240 | else { |
| 241 | hasEndStep = true; |
| 242 | } |
| 243 | |
| 244 | String name = state.getName(); |
| 245 | |
| 246 | SortedSet<StateTransition> set = transitionMap.get(name); |
| 247 | if (set == null) { |
| 248 | set = new TreeSet<StateTransition>(); |
| 249 | transitionMap.put(name, set); |
| 250 | } |
| 251 | set.add(stateTransition); |
| 252 | |
| 253 | } |
| 254 | |
| 255 | if (!hasEndStep) { |
| 256 | throw new IllegalArgumentException( |
| 257 | "No end state was found. You must specify at least one transition with no next state."); |
| 258 | } |
| 259 | |
| 260 | startState = stateTransitions.get(0).getState(); |
| 261 | |
| 262 | } |
| 263 | } |