src/main/java/net/pterodactylus/reactor/loader/ChainWatcher.java

   1 /*
   2  * Reactor - ChainWatcher.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.loader;
  19
  20 import java.io.File;
  21 import java.io.FilenameFilter;
  22 import java.util.HashMap;
  23 import java.util.Map;
  24 import java.util.Map.Entry;
  25 import java.util.concurrent.TimeUnit;
  26
  27 import javax.xml.bind.JAXBContext;
  28 import javax.xml.bind.JAXBException;
  29 import javax.xml.bind.Unmarshaller;
  30
  31 import net.pterodactylus.reactor.Reaction;
  32 import net.pterodactylus.reactor.engine.Engine;
  33 import net.pterodactylus.reactor.loader.Chain.Parameter;
  34 import net.pterodactylus.reactor.loader.Chain.Part;
  35
  36 import org.apache.log4j.Logger;
  37
  38 import com.google.common.base.Predicate;
  39 import com.google.common.collect.Maps;
  40 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  41 import com.google.common.util.concurrent.Uninterruptibles;
  42
  43 /**
  44  * Watches a directory for chain XML files and loads and unloads
  45  * {@link Reaction}s from the {@link Engine}.
  46  *
  47  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  48  */
  49 public class ChainWatcher extends AbstractExecutionThreadService {
  50
  51         /** The logger. */
  52         private static final Logger logger = Logger.getLogger(ChainWatcher.class);
  53
  54         /** The reaction loader. */
  55         private final ReactionLoader reactionLoader = new ReactionLoader();
  56
  57         /** The engine to load reactions with. */
  58         private final Engine engine;
  59
  60         /** The directory to watch for chain XML files. */
  61         private final String directory;
  62
  63         /**
  64          * Creates a new chain watcher.
  65          *
  66          * @param engine
  67          *            The engine to load reactions with
  68          * @param directory
  69          *            The directory to watch
  70          */
  71         public ChainWatcher(Engine engine, String directory) {
  72                 this.engine = engine;
  73                 this.directory = directory;
  74         }
  75
  76         //
  77         // ABSTRACTEXECUTIONTHREADSERVICE METHODS
  78         //
  79
  80         /**
  81          * {@inheritDoc}
  82          */
  83         @Override
  84         protected void run() throws Exception {
  85
  86                 /* loaded chains. */
  87                 final Map<String, Chain> loadedChains = new HashMap<String, Chain>();
  88
  89                 while (isRunning()) {
  90
  91                         /* check if directory is there. */
  92                         File directoryFile = new File(directory);
  93                         if (!directoryFile.exists() || !directoryFile.isDirectory() || !directoryFile.canRead()) {
  94                                 Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
  95                                 continue;
  96                         }
  97
  98                         /* list all files, scan for XMLs. */
  99                         logger.debug(String.format("Scanning %s...", directory));
 100                         File[] xmlFiles = directoryFile.listFiles(new FilenameFilter() {
 101
 102                                 @Override
 103                                 public boolean accept(File dir, String name) {
 104                                         return name.endsWith(".xml");
 105                                 }
 106                         });
 107                         logger.debug(String.format("Found %d XML file(s), parsing...", xmlFiles.length));
 108
 109                         /* now parse all XML files. */
 110                         Map<String, Chain> chains = new HashMap<String, Chain>();
 111                         for (File xmlFile : xmlFiles) {
 112
 113                                 /* parse XML file. */
 114                                 Chain chain = parseXmlFile(xmlFile);
 115
 116                                 /* dump chain */
 117                                 logger.debug(String.format(" Enabled: %s", chain.enabled()));
 118
 119                                 logger.debug(String.format(" Query: %s", chain.query().name()));
 120                                 for (Parameter parameter : chain.query().parameters()) {
 121                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 122                                 }
 123                                 for (Part filter : chain.filters()) {
 124                                         logger.debug(String.format(" Filter: %s", filter.name()));
 125                                         for (Parameter parameter : filter.parameters()) {
 126                                                 logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 127                                         }
 128                                 }
 129                                 logger.debug(String.format(" Trigger: %s", chain.trigger().name()));
 130                                 for (Parameter parameter : chain.trigger().parameters()) {
 131                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 132                                 }
 133                                 logger.debug(String.format(" Action: %s", chain.action().name()));
 134                                 for (Parameter parameter : chain.action().parameters()) {
 135                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 136                                 }
 137
 138                                 chains.put(xmlFile.getName(), chain);
 139                         }
 140
 141                         /* filter enabled chains. */
 142                         Map<String, Chain> enabledChains = Maps.filterEntries(chains, new Predicate<Entry<String, Chain>>() {
 143
 144                                 @Override
 145                                 public boolean apply(Entry<String, Chain> chainEntry) {
 146                                         return chainEntry.getValue().enabled();
 147                                 }
 148                         });
 149                         logger.debug(String.format("Found %d enabled Chain(s).", enabledChains.size()));
 150
 151                         /* check for removed chains. */
 152                         for (Entry<String, Chain> loadedChain : loadedChains.entrySet()) {
 153
 154                                 /* skip chains that still exist. */
 155                                 if (enabledChains.containsKey(loadedChain.getKey())) {
 156                                         continue;
 157                                 }
 158
 159                                 logger.info(String.format("Removing Chain: %s", loadedChain.getKey()));
 160                                 engine.removeReaction(loadedChain.getKey());
 161                                 loadedChains.remove(loadedChain.getKey());
 162                         }
 163
 164                         /* check for new chains. */
 165                         for (Entry<String, Chain> enabledChain : enabledChains.entrySet()) {
 166
 167                                 /* skip already loaded chains. */
 168                                 if (loadedChains.containsValue(enabledChain.getValue())) {
 169                                         continue;
 170                                 }
 171
 172                                 logger.info(String.format("Loading new Chain: %s", enabledChain.getKey()));
 173
 174                                 Reaction reaction = reactionLoader.loadReaction(enabledChain.getValue());
 175                                 engine.addReaction(enabledChain.getKey(), reaction);
 176                                 loadedChains.put(enabledChain.getKey(), enabledChain.getValue());
 177                         }
 178
 179                         /* wait before checking again. */
 180                         Uninterruptibles.sleepUninterruptibly(5, TimeUnit.SECONDS);
 181                 }
 182         }
 183
 184         //
 185         // STATIC METHODS
 186         //
 187
 188         /**
 189          * Parses the given XML file into a {@link Chain}.
 190          *
 191          * @param xmlFile
 192          *            The XML file to parse
 193          * @return The parsed chain
 194          */
 195         private static Chain parseXmlFile(File xmlFile) {
 196                 try {
 197                         JAXBContext context = JAXBContext.newInstance(Chain.class);
 198                         Unmarshaller unmarshaller = context.createUnmarshaller();
 199                         logger.debug(String.format("Reading %s...", xmlFile.getPath()));
 200                         return (Chain) unmarshaller.unmarshal(xmlFile);
 201                 } catch (JAXBException e) {
 202                         e.printStackTrace();
 203                         return null;
 204                 }
 205         }
 206
 207 }