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.Filter;
  26 import net.pterodactylus.reactor.Query;
  27 import net.pterodactylus.reactor.Reaction;
  28 import net.pterodactylus.reactor.Trigger;
  29 import net.pterodactylus.reactor.states.AbstractState;
  30
  31 import org.apache.log4j.Logger;
  32
  33 import com.google.common.collect.Maps;
  34 import com.google.common.collect.Sets;
  35 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  36 import com.google.common.util.concurrent.Uninterruptibles;
  37
  38 /**
  39  * Reactor main engine.
  40  *
  41  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  42  */
  43 public class Engine extends AbstractExecutionThreadService {
  44
  45         /** The logger. */
  46         private static final Logger logger = Logger.getLogger(Engine.class);
  47
  48         /** All defined reactions. */
  49         private final Set<Reaction> reactions = Sets.newHashSet();
  50
  51         /** Reaction states. */
  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 reaction
  62          *            The reaction to add to this engine
  63          */
  64         @SuppressWarnings("synthetic-access")
  65         public void addReaction(Reaction reaction) {
  66                 reactions.add(reaction);
  67                 reactionExecutions.put(reaction, new ReactionExecution());
  68         }
  69
  70         //
  71         // ABSTRACTSERVICE METHODS
  72         //
  73
  74         /**
  75          * {@inheritDoc}
  76          */
  77         @Override
  78         public void run() {
  79                 while (isRunning()) {
  80
  81                         /* delay if we have no reactions. */
  82                         if (reactions.isEmpty()) {
  83                                 logger.trace("Sleeping for 1 second while no Reactions available.");
  84                                 Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
  85                                 continue;
  86                         }
  87
  88                         /* find next reaction. */
  89                         SortedMap<Long, Reaction> nextReactions = Maps.newTreeMap();
  90                         for (Reaction reaction : reactions) {
  91                                 ReactionExecution reactionExecution = reactionExecutions.get(reaction);
  92                                 nextReactions.put(reactionExecution.lastExecutionTime() + reaction.updateInterval(), reaction);
  93                         }
  94                         Reaction nextReaction = nextReactions.get(nextReactions.firstKey());
  95                         ReactionExecution reactionExecution = reactionExecutions.get(nextReaction);
  96                         logger.debug(String.format("Next Reaction: %s.", nextReaction));
  97
  98                         /* wait until the next reaction has to run. */
  99                         while (isRunning()) {
 100                                 long waitTime = (reactionExecution.lastExecutionTime() + nextReaction.updateInterval()) - System.currentTimeMillis();
 101                                 logger.debug(String.format("Time to wait for next Reaction: %d millseconds.", waitTime));
 102                                 if (waitTime <= 0) {
 103                                         break;
 104                                 }
 105                                 try {
 106                                         logger.debug(String.format("Waiting for %d milliseconds.", waitTime));
 107                                         TimeUnit.MILLISECONDS.sleep(waitTime);
 108                                 } catch (InterruptedException ie1) {
 109                                         /* we’re looping! */
 110                                 }
 111                         }
 112
 113                         /* are we still running? */
 114                         if (!isRunning()) {
 115                                 break;
 116                         }
 117
 118                         /* run reaction. */
 119                         reactionExecution.setLastExecutionTime(System.currentTimeMillis());
 120                         Query query = nextReaction.query();
 121                         net.pterodactylus.reactor.State state;
 122                         try {
 123                                 logger.debug("Querying system...");
 124                                 state = query.state();
 125                                 logger.debug("System queried.");
 126                         } catch (Throwable t1) {
 127                                 logger.warn("Querying system failed!", t1);
 128                                 state = new AbstractState(t1) {
 129                                         /* no further state. */
 130                                 };
 131                         }
 132                         logger.debug(String.format("State is %s.", state));
 133
 134                         /* convert states. */
 135                         for (Filter filter : nextReaction.filters()) {
 136                                 net.pterodactylus.reactor.State newState = filter.filter(state);
 137                                 logger.debug(String.format("Old state is %s, new state is %s.", state, newState));
 138                                 state = newState;
 139                         }
 140                         reactionExecution.addState(state);
 141
 142                         /* only run trigger if we have collected two states. */
 143                         boolean triggerHit = false;
 144                         if (reactionExecution.previousState() != null) {
 145                                 Trigger trigger = nextReaction.trigger();
 146                                 logger.debug("Checking Trigger for changes...");
 147                                 triggerHit = trigger.triggers(reactionExecution.currentState(), reactionExecution.previousState());
 148                         }
 149
 150                         /* run action if trigger was hit. */
 151                         logger.debug(String.format("Trigger was hit: %s.", triggerHit));
 152                         if (triggerHit) {
 153                                 logger.info("Executing Action...");
 154                                 nextReaction.action().execute(reactionExecution.currentState(), reactionExecution.previousState());
 155                         }
 156                 }
 157         }
 158
 159         /**
 160          * Stores execution states of a {@link Reaction}.
 161          *
 162          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 163          */
 164         private static class ReactionExecution {
 165
 166                 /** The time the reaction was last executed. */
 167                 private long lastExecutionTime;
 168
 169                 /** The previous state of the reaction. */
 170                 private net.pterodactylus.reactor.State previousState;
 171
 172                 /** The current state of the reaction. */
 173                 private net.pterodactylus.reactor.State currentState;
 174
 175                 //
 176                 // ACCESSORS
 177                 //
 178
 179                 /**
 180                  * Returns the time the reaction was last executed. If the reaction was
 181                  * not yet executed, this method returns {@code 0}.
 182                  *
 183                  * @return The last execution time of the reaction (in milliseconds
 184                  *         since Jan 1, 1970 UTC)
 185                  */
 186                 public long lastExecutionTime() {
 187                         return lastExecutionTime;
 188                 }
 189
 190                 /**
 191                  * Returns the current state of the reaction. If the reaction was not
 192                  * yet executed, this method returns {@code null}.
 193                  *
 194                  * @return The current state of the reaction
 195                  */
 196                 public net.pterodactylus.reactor.State currentState() {
 197                         return currentState;
 198                 }
 199
 200                 /**
 201                  * Returns the previous state of the reaction. If the reaction was not
 202                  * yet executed at least twice, this method returns {@code null}.
 203                  *
 204                  * @return The previous state of the reaction
 205                  */
 206                 public net.pterodactylus.reactor.State previousState() {
 207                         return previousState;
 208                 }
 209
 210                 /**
 211                  * Sets the last execution time of the reaction.
 212                  *
 213                  * @param lastExecutionTime
 214                  *            The last execution time of the reaction (in milliseconds
 215                  *            since Jan 1, 1970 UTC)
 216                  * @return This execution
 217                  */
 218                 public ReactionExecution setLastExecutionTime(long lastExecutionTime) {
 219                         this.lastExecutionTime = lastExecutionTime;
 220                         return this;
 221                 }
 222
 223                 //
 224                 // ACTIONS
 225                 //
 226
 227                 /**
 228                  * Adds the given state as current state and moves the current state
 229                  * into the previous state.
 230                  *
 231                  * @param state
 232                  *            The new current state
 233                  * @return This execution
 234                  */
 235                 public ReactionExecution addState(net.pterodactylus.reactor.State state) {
 236                         previousState = currentState;
 237                         currentState = state;
 238                         return this;
 239                 }
 240
 241         }
 242
 243 }