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         // ABSTRACTSERVICE METHODS
  83         //
  84
  85         /**
  86          * {@inheritDoc}
  87          */
  88         @Override
  89         public void run() {
  90                 while (isRunning()) {
  91
  92                         /* delay if we have no reactions. */
  93                         synchronized (reactions) {
  94                                 if (reactions.isEmpty()) {
  95                                         logger.debug("Sleeping while no Reactions available.");
  96                                         try {
  97                                                 reactions.wait();
  98                                         } catch (InterruptedException ie1) {
  99                                                 /* ignore, we’re looping anyway. */
 100                                         }
 101                                         continue;
 102                                 }
 103                         }
 104
 105                         /* find next reaction. */
 106                         SortedMap<Long, Reaction> nextReactions = Maps.newTreeMap();
 107                         Reaction nextReaction;
 108                         ReactionExecution reactionExecution;
 109                         synchronized (reactions) {
 110                                 for (Reaction reaction : reactions.values()) {
 111                                         nextReactions.put(reactionExecutions.get(reaction).lastExecutionTime() + reaction.updateInterval(), reaction);
 112                                 }
 113                                 nextReaction = nextReactions.get(nextReactions.firstKey());
 114                                 reactionExecution = reactionExecutions.get(nextReaction);
 115                         }
 116                         logger.debug(String.format("Next Reaction: %s.", nextReaction));
 117
 118                         /* wait until the next reaction has to run. */
 119                         long waitTime = (reactionExecution.lastExecutionTime() + nextReaction.updateInterval()) - System.currentTimeMillis();
 120                         logger.debug(String.format("Time to wait for next Reaction: %d millseconds.", waitTime));
 121                         if (waitTime > 0) {
 122                                 synchronized (reactions) {
 123                                         try {
 124                                                 logger.debug(String.format("Waiting for %d milliseconds.", waitTime));
 125                                                 reactions.wait(waitTime);
 126                                         } catch (InterruptedException ie1) {
 127                                                 /* we’re looping! */
 128                                         }
 129                                 }
 130
 131                                 /* re-start loop to check for new reactions. */
 132                                 continue;
 133                         }
 134
 135                         /* run reaction. */
 136                         reactionExecution.setLastExecutionTime(System.currentTimeMillis());
 137                         Query query = nextReaction.query();
 138                         net.pterodactylus.reactor.State state;
 139                         try {
 140                                 logger.debug("Querying system...");
 141                                 state = query.state();
 142                                 if (state == null) {
 143                                         state = FailedState.INSTANCE;
 144                                 }
 145                                 logger.debug("System queried.");
 146                         } catch (Throwable t1) {
 147                                 logger.warn("Querying system failed!", t1);
 148                                 state = new AbstractState(t1) {
 149                                         /* no further state. */
 150                                 };
 151                         }
 152                         logger.debug(String.format("State is %s.", state));
 153
 154                         /* convert states. */
 155                         for (Filter filter : nextReaction.filters()) {
 156                                 if (state.success()) {
 157                                         net.pterodactylus.reactor.State newState = filter.filter(state);
 158                                         logger.debug(String.format("Old state is %s, new state is %s.", state, newState));
 159                                         state = newState;
 160                                 }
 161                         }
 162                         if (state.success()) {
 163                                 reactionExecution.addState(state);
 164                         }
 165
 166                         /* only run trigger if we have collected two states. */
 167                         Trigger trigger = nextReaction.trigger();
 168                         boolean triggerHit = false;
 169                         if ((reactionExecution.previousState() != null) && state.success()) {
 170                                 logger.debug("Checking Trigger for changes...");
 171                                 triggerHit = trigger.triggers(reactionExecution.currentState(), reactionExecution.previousState());
 172                         }
 173
 174                         /* run action if trigger was hit. */
 175                         logger.debug(String.format("Trigger was hit: %s.", triggerHit));
 176                         if (triggerHit) {
 177                                 logger.info("Executing Action...");
 178                                 nextReaction.action().execute(trigger.output());
 179                         }
 180
 181                 }
 182         }
 183
 184         /**
 185          * Stores execution states of a {@link Reaction}.
 186          *
 187          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 188          */
 189         private static class ReactionExecution {
 190
 191                 /** The time the reaction was last executed. */
 192                 private long lastExecutionTime;
 193
 194                 /** The previous state of the reaction. */
 195                 private net.pterodactylus.reactor.State previousState;
 196
 197                 /** The current state of the reaction. */
 198                 private net.pterodactylus.reactor.State currentState;
 199
 200                 //
 201                 // ACCESSORS
 202                 //
 203
 204                 /**
 205                  * Returns the time the reaction was last executed. If the reaction was
 206                  * not yet executed, this method returns {@code 0}.
 207                  *
 208                  * @return The last execution time of the reaction (in milliseconds
 209                  *         since Jan 1, 1970 UTC)
 210                  */
 211                 public long lastExecutionTime() {
 212                         return lastExecutionTime;
 213                 }
 214
 215                 /**
 216                  * Returns the current state of the reaction. If the reaction was not
 217                  * yet executed, this method returns {@code null}.
 218                  *
 219                  * @return The current state of the reaction
 220                  */
 221                 public net.pterodactylus.reactor.State currentState() {
 222                         return currentState;
 223                 }
 224
 225                 /**
 226                  * Returns the previous state of the reaction. If the reaction was not
 227                  * yet executed at least twice, this method returns {@code null}.
 228                  *
 229                  * @return The previous state of the reaction
 230                  */
 231                 public net.pterodactylus.reactor.State previousState() {
 232                         return previousState;
 233                 }
 234
 235                 /**
 236                  * Sets the last execution time of the reaction.
 237                  *
 238                  * @param lastExecutionTime
 239                  *            The last execution time of the reaction (in milliseconds
 240                  *            since Jan 1, 1970 UTC)
 241                  * @return This execution
 242                  */
 243                 public ReactionExecution setLastExecutionTime(long lastExecutionTime) {
 244                         this.lastExecutionTime = lastExecutionTime;
 245                         return this;
 246                 }
 247
 248                 //
 249                 // ACTIONS
 250                 //
 251
 252                 /**
 253                  * Adds the given state as current state and moves the current state
 254                  * into the previous state.
 255                  *
 256                  * @param state
 257                  *            The new current state
 258                  * @return This execution
 259                  */
 260                 public ReactionExecution addState(net.pterodactylus.reactor.State state) {
 261                         previousState = currentState;
 262                         currentState = state;
 263                         return this;
 264                 }
 265
 266         }
 267
 268 }