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 import net.pterodactylus.reactor.states.FailedState;
  31
  32 import org.apache.log4j.Logger;
  33
  34 import com.google.common.collect.Maps;
  35 import com.google.common.collect.Sets;
  36 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  37 import com.google.common.util.concurrent.Uninterruptibles;
  38
  39 /**
  40  * Reactor main engine.
  41  *
  42  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  43  */
  44 public class Engine extends AbstractExecutionThreadService {
  45
  46         /** The logger. */
  47         private static final Logger logger = Logger.getLogger(Engine.class);
  48
  49         /** All defined reactions. */
  50         private final Set<Reaction> reactions = Sets.newHashSet();
  51
  52         /** Reaction states. */
  53         private final Map<Reaction, ReactionExecution> reactionExecutions = Maps.newHashMap();
  54
  55         //
  56         // ACCESSORS
  57         //
  58
  59         /**
  60          * Adds the given reaction to this engine.
  61          *
  62          * @param reaction
  63          *            The reaction to add to this engine
  64          */
  65         @SuppressWarnings("synthetic-access")
  66         public void addReaction(Reaction reaction) {
  67                 reactions.add(reaction);
  68                 reactionExecutions.put(reaction, new ReactionExecution());
  69         }
  70
  71         //
  72         // ABSTRACTSERVICE METHODS
  73         //
  74
  75         /**
  76          * {@inheritDoc}
  77          */
  78         @Override
  79         public void run() {
  80                 while (isRunning()) {
  81
  82                         /* delay if we have no reactions. */
  83                         if (reactions.isEmpty()) {
  84                                 logger.trace("Sleeping for 1 second while no Reactions available.");
  85                                 Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
  86                                 continue;
  87                         }
  88
  89                         /* find next reaction. */
  90                         SortedMap<Long, Reaction> nextReactions = Maps.newTreeMap();
  91                         for (Reaction reaction : reactions) {
  92                                 ReactionExecution reactionExecution = reactionExecutions.get(reaction);
  93                                 nextReactions.put(reactionExecution.lastExecutionTime() + reaction.updateInterval(), reaction);
  94                         }
  95                         Reaction nextReaction = nextReactions.get(nextReactions.firstKey());
  96                         ReactionExecution reactionExecution = reactionExecutions.get(nextReaction);
  97                         logger.debug(String.format("Next Reaction: %s.", nextReaction));
  98
  99                         /* wait until the next reaction has to run. */
 100                         while (isRunning()) {
 101                                 long waitTime = (reactionExecution.lastExecutionTime() + nextReaction.updateInterval()) - System.currentTimeMillis();
 102                                 logger.debug(String.format("Time to wait for next Reaction: %d millseconds.", waitTime));
 103                                 if (waitTime <= 0) {
 104                                         break;
 105                                 }
 106                                 try {
 107                                         logger.debug(String.format("Waiting for %d milliseconds.", waitTime));
 108                                         TimeUnit.MILLISECONDS.sleep(waitTime);
 109                                 } catch (InterruptedException ie1) {
 110                                         /* we’re looping! */
 111                                 }
 112                         }
 113
 114                         /* are we still running? */
 115                         if (!isRunning()) {
 116                                 break;
 117                         }
 118
 119                         /* run reaction. */
 120                         reactionExecution.setLastExecutionTime(System.currentTimeMillis());
 121                         Query query = nextReaction.query();
 122                         net.pterodactylus.reactor.State state;
 123                         try {
 124                                 logger.debug("Querying system...");
 125                                 state = query.state();
 126                                 if (state == null) {
 127                                         state = FailedState.INSTANCE;
 128                                 }
 129                                 logger.debug("System queried.");
 130                         } catch (Throwable t1) {
 131                                 logger.warn("Querying system failed!", t1);
 132                                 state = new AbstractState(t1) {
 133                                         /* no further state. */
 134                                 };
 135                         }
 136                         logger.debug(String.format("State is %s.", state));
 137
 138                         /* convert states. */
 139                         for (Filter filter : nextReaction.filters()) {
 140                                 if (state.success()) {
 141                                         net.pterodactylus.reactor.State newState = filter.filter(state);
 142                                         logger.debug(String.format("Old state is %s, new state is %s.", state, newState));
 143                                         state = newState;
 144                                 }
 145                         }
 146                         if (state.success()) {
 147                                 reactionExecution.addState(state);
 148                         }
 149
 150                         /* only run trigger if we have collected two states. */
 151                         Trigger trigger = nextReaction.trigger();
 152                         boolean triggerHit = false;
 153                         if (reactionExecution.previousState() != null) {
 154                                 logger.debug("Checking Trigger for changes...");
 155                                 triggerHit = trigger.triggers(reactionExecution.currentState(), reactionExecution.previousState());
 156                         }
 157
 158                         /* run action if trigger was hit. */
 159                         logger.debug(String.format("Trigger was hit: %s.", triggerHit));
 160                         if (triggerHit) {
 161                                 logger.info("Executing Action...");
 162                                 nextReaction.action().execute(trigger.trigger());
 163                         }
 164
 165                 }
 166         }
 167
 168         /**
 169          * Stores execution states of a {@link Reaction}.
 170          *
 171          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 172          */
 173         private static class ReactionExecution {
 174
 175                 /** The time the reaction was last executed. */
 176                 private long lastExecutionTime;
 177
 178                 /** The previous state of the reaction. */
 179                 private net.pterodactylus.reactor.State previousState;
 180
 181                 /** The current state of the reaction. */
 182                 private net.pterodactylus.reactor.State currentState;
 183
 184                 //
 185                 // ACCESSORS
 186                 //
 187
 188                 /**
 189                  * Returns the time the reaction was last executed. If the reaction was
 190                  * not yet executed, this method returns {@code 0}.
 191                  *
 192                  * @return The last execution time of the reaction (in milliseconds
 193                  *         since Jan 1, 1970 UTC)
 194                  */
 195                 public long lastExecutionTime() {
 196                         return lastExecutionTime;
 197                 }
 198
 199                 /**
 200                  * Returns the current state of the reaction. If the reaction was not
 201                  * yet executed, this method returns {@code null}.
 202                  *
 203                  * @return The current state of the reaction
 204                  */
 205                 public net.pterodactylus.reactor.State currentState() {
 206                         return currentState;
 207                 }
 208
 209                 /**
 210                  * Returns the previous state of the reaction. If the reaction was not
 211                  * yet executed at least twice, this method returns {@code null}.
 212                  *
 213                  * @return The previous state of the reaction
 214                  */
 215                 public net.pterodactylus.reactor.State previousState() {
 216                         return previousState;
 217                 }
 218
 219                 /**
 220                  * Sets the last execution time of the reaction.
 221                  *
 222                  * @param lastExecutionTime
 223                  *            The last execution time of the reaction (in milliseconds
 224                  *            since Jan 1, 1970 UTC)
 225                  * @return This execution
 226                  */
 227                 public ReactionExecution setLastExecutionTime(long lastExecutionTime) {
 228                         this.lastExecutionTime = lastExecutionTime;
 229                         return this;
 230                 }
 231
 232                 //
 233                 // ACTIONS
 234                 //
 235
 236                 /**
 237                  * Adds the given state as current state and moves the current state
 238                  * into the previous state.
 239                  *
 240                  * @param state
 241                  *            The new current state
 242                  * @return This execution
 243                  */
 244                 public ReactionExecution addState(net.pterodactylus.reactor.State state) {
 245                         previousState = currentState;
 246                         currentState = state;
 247                         return this;
 248                 }
 249
 250         }
 251
 252 }