src/main/java/net/pterodactylus/reactor/engine/Engine.java

   1 /*
   2  * Reactor - Engine.java - Copyright © 2013 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.reactor.engine;
  19
  20 import java.util.HashMap;
  21 import java.util.Map;
  22 import java.util.SortedMap;
  23
  24 import net.pterodactylus.reactor.Filter;
  25 import net.pterodactylus.reactor.Query;
  26 import net.pterodactylus.reactor.Reaction;
  27 import net.pterodactylus.reactor.Trigger;
  28 import net.pterodactylus.reactor.states.AbstractState;
  29 import net.pterodactylus.reactor.states.FailedState;
  30
  31 import org.apache.log4j.Logger;
  32
  33 import com.google.common.collect.Maps;
  34 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  35
  36 /**
  37  * Reactor main engine.
  38  *
  39  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  40  */
  41 public class Engine extends AbstractExecutionThreadService {
  42
  43         /** The logger. */
  44         private static final Logger logger = Logger.getLogger(Engine.class);
  45
  46         /** All defined reactions. */
  47         /* synchronize on itself. */
  48         private final Map<String, Reaction> reactions = new HashMap<String, Reaction>();
  49
  50         /** Reaction states. */
  51         /* synchronize on reactions. */
  52         private final Map<Reaction, ReactionExecution> reactionExecutions = Maps.newHashMap();
  53
  54         //
  55         // ACCESSORS
  56         //
  57
  58         /**
  59          * Adds the given reaction to this engine.
  60          *
  61          * @param name
  62          *            The name of the reaction
  63          * @param reaction
  64          *            The reaction to add to this engine
  65          * @throws IllegalStateException
  66          *             if the engine already contains a {@link Reaction} with the
  67          *             given name
  68          */
  69         @SuppressWarnings("synthetic-access")
  70         public void addReaction(String name, Reaction reaction) {
  71                 synchronized (reactions) {
  72                         if (reactions.containsKey(name)) {
  73                                 throw new IllegalStateException(String.format("Engine already contains a Reaction named “%s!”", name));
  74                         }
  75                         reactions.put(name, reaction);
  76                         reactionExecutions.put(reaction, new ReactionExecution());
  77                         reactions.notifyAll();
  78                 }
  79         }
  80
  81         /**
  82          * Removes the reaction with the given name.
  83          *
  84          * @param name
  85          *            The name of the reaction to remove
  86          */
  87         public void removeReaction(String name) {
  88                 synchronized (reactions) {
  89                         if (!reactions.containsKey(name)) {
  90                                 return;
  91                         }
  92                         Reaction reaction = reactions.remove(name);
  93                         reactionExecutions.remove(reaction);
  94                         reactions.notifyAll();
  95                 }
  96         }
  97
  98         //
  99         // ABSTRACTSERVICE METHODS
 100         //
 101
 102         /**
 103          * {@inheritDoc}
 104          */
 105         @Override
 106         public void run() {
 107                 while (isRunning()) {
 108
 109                         /* delay if we have no reactions. */
 110                         synchronized (reactions) {
 111                                 if (reactions.isEmpty()) {
 112                                         logger.debug("Sleeping while no Reactions available.");
 113                                         try {
 114                                                 reactions.wait();
 115                                         } catch (InterruptedException ie1) {
 116                                                 /* ignore, we’re looping anyway. */
 117                                         }
 118                                         continue;
 119                                 }
 120                         }
 121
 122                         /* find next reaction. */
 123                         SortedMap<Long, Reaction> nextReactions = Maps.newTreeMap();
 124                         Reaction nextReaction;
 125                         ReactionExecution reactionExecution;
 126                         synchronized (reactions) {
 127                                 for (Reaction reaction : reactions.values()) {
 128                                         nextReactions.put(reactionExecutions.get(reaction).lastExecutionTime() + reaction.updateInterval(), reaction);
 129                                 }
 130                                 nextReaction = nextReactions.get(nextReactions.firstKey());
 131                                 reactionExecution = reactionExecutions.get(nextReaction);
 132                         }
 133                         logger.debug(String.format("Next Reaction: %s.", nextReaction));
 134
 135                         /* wait until the next reaction has to run. */
 136                         long waitTime = (reactionExecution.lastExecutionTime() + nextReaction.updateInterval()) - System.currentTimeMillis();
 137                         logger.debug(String.format("Time to wait for next Reaction: %d millseconds.", waitTime));
 138                         if (waitTime > 0) {
 139                                 synchronized (reactions) {
 140                                         try {
 141                                                 logger.debug(String.format("Waiting for %d milliseconds.", waitTime));
 142                                                 reactions.wait(waitTime);
 143                                         } catch (InterruptedException ie1) {
 144                                                 /* we’re looping! */
 145                                         }
 146                                 }
 147
 148                                 /* re-start loop to check for new reactions. */
 149                                 continue;
 150                         }
 151
 152                         /* run reaction. */
 153                         reactionExecution.setLastExecutionTime(System.currentTimeMillis());
 154                         Query query = nextReaction.query();
 155                         net.pterodactylus.reactor.State state;
 156                         try {
 157                                 logger.debug("Querying system...");
 158                                 state = query.state();
 159                                 if (state == null) {
 160                                         state = FailedState.INSTANCE;
 161                                 }
 162                                 logger.debug("System queried.");
 163                         } catch (Throwable t1) {
 164                                 logger.warn("Querying system failed!", t1);
 165                                 state = new AbstractState(t1) {
 166                                         /* no further state. */
 167                                 };
 168                         }
 169                         logger.debug(String.format("State is %s.", state));
 170
 171                         /* convert states. */
 172                         for (Filter filter : nextReaction.filters()) {
 173                                 if (state.success()) {
 174                                         net.pterodactylus.reactor.State newState = filter.filter(state);
 175                                         logger.debug(String.format("Old state is %s, new state is %s.", state, newState));
 176                                         state = newState;
 177                                 }
 178                         }
 179                         if (state.success()) {
 180                                 reactionExecution.addState(state);
 181                         }
 182
 183                         /* only run trigger if we have collected two states. */
 184                         Trigger trigger = nextReaction.trigger();
 185                         boolean triggerHit = false;
 186                         if ((reactionExecution.previousState() != null) && state.success()) {
 187                                 logger.debug("Checking Trigger for changes...");
 188                                 triggerHit = trigger.triggers(reactionExecution.currentState(), reactionExecution.previousState());
 189                         }
 190
 191                         /* run action if trigger was hit. */
 192                         logger.debug(String.format("Trigger was hit: %s.", triggerHit));
 193                         if (triggerHit) {
 194                                 logger.info("Executing Action...");
 195                                 nextReaction.action().execute(trigger.output());
 196                         }
 197
 198                 }
 199         }
 200
 201         /**
 202          * Stores execution states of a {@link Reaction}.
 203          *
 204          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 205          */
 206         private static class ReactionExecution {
 207
 208                 /** The time the reaction was last executed. */
 209                 private long lastExecutionTime;
 210
 211                 /** The previous state of the reaction. */
 212                 private net.pterodactylus.reactor.State previousState;
 213
 214                 /** The current state of the reaction. */
 215                 private net.pterodactylus.reactor.State currentState;
 216
 217                 //
 218                 // ACCESSORS
 219                 //
 220
 221                 /**
 222                  * Returns the time the reaction was last executed. If the reaction was
 223                  * not yet executed, this method returns {@code 0}.
 224                  *
 225                  * @return The last execution time of the reaction (in milliseconds
 226                  *         since Jan 1, 1970 UTC)
 227                  */
 228                 public long lastExecutionTime() {
 229                         return lastExecutionTime;
 230                 }
 231
 232                 /**
 233                  * Returns the current state of the reaction. If the reaction was not
 234                  * yet executed, this method returns {@code null}.
 235                  *
 236                  * @return The current state of the reaction
 237                  */
 238                 public net.pterodactylus.reactor.State currentState() {
 239                         return currentState;
 240                 }
 241
 242                 /**
 243                  * Returns the previous state of the reaction. If the reaction was not
 244                  * yet executed at least twice, this method returns {@code null}.
 245                  *
 246                  * @return The previous state of the reaction
 247                  */
 248                 public net.pterodactylus.reactor.State previousState() {
 249                         return previousState;
 250                 }
 251
 252                 /**
 253                  * Sets the last execution time of the reaction.
 254                  *
 255                  * @param lastExecutionTime
 256                  *            The last execution time of the reaction (in milliseconds
 257                  *            since Jan 1, 1970 UTC)
 258                  * @return This execution
 259                  */
 260                 public ReactionExecution setLastExecutionTime(long lastExecutionTime) {
 261                         this.lastExecutionTime = lastExecutionTime;
 262                         return this;
 263                 }
 264
 265                 //
 266                 // ACTIONS
 267                 //
 268
 269                 /**
 270                  * Adds the given state as current state and moves the current state
 271                  * into the previous state.
 272                  *
 273                  * @param state
 274                  *            The new current state
 275                  * @return This execution
 276                  */
 277                 public ReactionExecution addState(net.pterodactylus.reactor.State state) {
 278                         previousState = currentState;
 279                         currentState = state;
 280                         return this;
 281                 }
 282
 283         }
 284
 285 }