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.Map;
  21 import java.util.Set;
  22 import java.util.SortedMap;
  23 import java.util.concurrent.TimeUnit;
  24
  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
  30 import org.apache.log4j.Logger;
  31
  32 import com.google.common.collect.Maps;
  33 import com.google.common.collect.Sets;
  34 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  35 import com.google.common.util.concurrent.Uninterruptibles;
  36
  37 /**
  38  * Reactor main engine.
  39  *
  40  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  41  */
  42 public class Engine extends AbstractExecutionThreadService {
  43
  44         /** The logger. */
  45         private static final Logger logger = Logger.getLogger(Engine.class);
  46
  47         /** All defined reactions. */
  48         private final Set<Reaction> reactions = Sets.newHashSet();
  49
  50         /** Reaction states. */
  51         private final Map<Reaction, ReactionExecution> reactionExecutions = Maps.newHashMap();
  52
  53         //
  54         // ACCESSORS
  55         //
  56
  57         /**
  58          * Adds the given reaction to this engine.
  59          *
  60          * @param reaction
  61          *            The reaction to add to this engine
  62          */
  63         @SuppressWarnings("synthetic-access")
  64         public void addReaction(Reaction reaction) {
  65                 reactions.add(reaction);
  66                 reactionExecutions.put(reaction, new ReactionExecution());
  67         }
  68
  69         //
  70         // ABSTRACTSERVICE METHODS
  71         //
  72
  73         /**
  74          * {@inheritDoc}
  75          */
  76         @Override
  77         public void run() {
  78                 while (isRunning()) {
  79
  80                         /* delay if we have no reactions. */
  81                         if (reactions.isEmpty()) {
  82                                 logger.trace("Sleeping for 1 second while no Reactions available.");
  83                                 Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
  84                                 continue;
  85                         }
  86
  87                         /* find next reaction. */
  88                         SortedMap<Long, Reaction> nextReactions = Maps.newTreeMap();
  89                         for (Reaction reaction : reactions) {
  90                                 ReactionExecution reactionExecution = reactionExecutions.get(reaction);
  91                                 nextReactions.put(reactionExecution.lastExecutionTime() + reaction.updateInterval(), reaction);
  92                         }
  93                         Reaction nextReaction = nextReactions.get(nextReactions.firstKey());
  94                         ReactionExecution reactionExecution = reactionExecutions.get(nextReaction);
  95                         logger.debug(String.format("Next Reaction: %s.", nextReaction));
  96
  97                         /* wait until the next reaction has to run. */
  98                         while (isRunning()) {
  99                                 long waitTime = (reactionExecution.lastExecutionTime() + nextReaction.updateInterval()) - System.currentTimeMillis();
 100                                 logger.debug(String.format("Time to wait for next Reaction: %d millseconds.", waitTime));
 101                                 if (waitTime <= 0) {
 102                                         break;
 103                                 }
 104                                 try {
 105                                         logger.debug(String.format("Waiting for %d milliseconds.", waitTime));
 106                                         TimeUnit.MILLISECONDS.sleep(waitTime);
 107                                 } catch (InterruptedException ie1) {
 108                                         /* we’re looping! */
 109                                 }
 110                         }
 111
 112                         /* are we still running? */
 113                         if (!isRunning()) {
 114                                 break;
 115                         }
 116
 117                         /* run reaction. */
 118                         reactionExecution.setLastExecutionTime(System.currentTimeMillis());
 119                         Query query = nextReaction.query();
 120                         net.pterodactylus.reactor.State state;
 121                         try {
 122                                 logger.debug("Querying system...");
 123                                 state = query.state();
 124                                 logger.debug("System queried.");
 125                         } catch (Throwable t1) {
 126                                 logger.warn("Querying system failed!", t1);
 127                                 state = new AbstractState(t1) {
 128                                         /* no further state. */
 129                                 };
 130                         }
 131                         logger.debug(String.format("State is %s.", state));
 132                         reactionExecution.addState(state);
 133
 134                         /* only run trigger if we have collected two states. */
 135                         boolean triggerHit = false;
 136                         if (reactionExecution.previousState() != null) {
 137                                 Trigger trigger = nextReaction.trigger();
 138                                 logger.debug("Checking Trigger for changes...");
 139                                 triggerHit = trigger.triggers(reactionExecution.currentState(), reactionExecution.previousState());
 140                         }
 141
 142                         /* run action if trigger was hit. */
 143                         logger.debug(String.format("Trigger was hit: %s.", triggerHit));
 144                         if (triggerHit) {
 145                                 logger.info("Executing Action...");
 146                                 nextReaction.action().execute(reactionExecution.currentState(), reactionExecution.previousState());
 147                         }
 148                 }
 149         }
 150
 151         /**
 152          * Stores execution states of a {@link Reaction}.
 153          *
 154          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 155          */
 156         private static class ReactionExecution {
 157
 158                 /** The time the reaction was last executed. */
 159                 private long lastExecutionTime;
 160
 161                 /** The previous state of the reaction. */
 162                 private net.pterodactylus.reactor.State previousState;
 163
 164                 /** The current state of the reaction. */
 165                 private net.pterodactylus.reactor.State currentState;
 166
 167                 //
 168                 // ACCESSORS
 169                 //
 170
 171                 /**
 172                  * Returns the time the reaction was last executed. If the reaction was
 173                  * not yet executed, this method returns {@code 0}.
 174                  *
 175                  * @return The last execution time of the reaction (in milliseconds
 176                  *         since Jan 1, 1970 UTC)
 177                  */
 178                 public long lastExecutionTime() {
 179                         return lastExecutionTime;
 180                 }
 181
 182                 /**
 183                  * Returns the current state of the reaction. If the reaction was not
 184                  * yet executed, this method returns {@code null}.
 185                  *
 186                  * @return The current state of the reaction
 187                  */
 188                 public net.pterodactylus.reactor.State currentState() {
 189                         return currentState;
 190                 }
 191
 192                 /**
 193                  * Returns the previous state of the reaction. If the reaction was not
 194                  * yet executed at least twice, this method returns {@code null}.
 195                  *
 196                  * @return The previous state of the reaction
 197                  */
 198                 public net.pterodactylus.reactor.State previousState() {
 199                         return previousState;
 200                 }
 201
 202                 /**
 203                  * Sets the last execution time of the reaction.
 204                  *
 205                  * @param lastExecutionTime
 206                  *            The last execution time of the reaction (in milliseconds
 207                  *            since Jan 1, 1970 UTC)
 208                  * @return This execution
 209                  */
 210                 public ReactionExecution setLastExecutionTime(long lastExecutionTime) {
 211                         this.lastExecutionTime = lastExecutionTime;
 212                         return this;
 213                 }
 214
 215                 //
 216                 // ACTIONS
 217                 //
 218
 219                 /**
 220                  * Adds the given state as current state and moves the current state
 221                  * into the previous state.
 222                  *
 223                  * @param state
 224                  *            The new current state
 225                  * @return This execution
 226                  */
 227                 public ReactionExecution addState(net.pterodactylus.reactor.State state) {
 228                         previousState = currentState;
 229                         currentState = state;
 230                         return this;
 231                 }
 232
 233         }
 234
 235 }