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.io.IOException;
  23 import java.util.HashMap;
  24 import java.util.HashSet;
  25 import java.util.Map;
  26 import java.util.Map.Entry;
  27 import java.util.Set;
  28 import java.util.concurrent.TimeUnit;
  29
  30 import net.pterodactylus.reactor.Reaction;
  31 import net.pterodactylus.reactor.engine.Engine;
  32 import net.pterodactylus.reactor.loader.Chain.Parameter;
  33 import net.pterodactylus.reactor.loader.Chain.Part;
  34
  35 import org.apache.log4j.Logger;
  36
  37 import com.fasterxml.jackson.core.JsonParseException;
  38 import com.fasterxml.jackson.databind.JsonMappingException;
  39 import com.fasterxml.jackson.databind.ObjectMapper;
  40 import com.google.common.base.Predicate;
  41 import com.google.common.collect.Maps;
  42 import com.google.common.util.concurrent.AbstractExecutionThreadService;
  43 import com.google.common.util.concurrent.Uninterruptibles;
  44
  45 /**
  46  * Watches a directory for chain configuration files and loads and unloads
  47  * {@link Reaction}s from the {@link Engine}.
  48  *
  49  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  50  */
  51 public class ChainWatcher extends AbstractExecutionThreadService {
  52
  53         /** The logger. */
  54         private static final Logger logger = Logger.getLogger(ChainWatcher.class);
  55
  56         /** The JSON object mapper. */
  57         private static final ObjectMapper objectMapper = new ObjectMapper();
  58
  59         /** The reaction loader. */
  60         private final ReactionLoader reactionLoader = new ReactionLoader();
  61
  62         /** The engine to load reactions with. */
  63         private final Engine engine;
  64
  65         /** The directory to watch for chain configuration files. */
  66         private final String directory;
  67
  68         /**
  69          * Creates a new chain watcher.
  70          *
  71          * @param engine
  72          *            The engine to load reactions with
  73          * @param directory
  74          *            The directory to watch
  75          */
  76         public ChainWatcher(Engine engine, String directory) {
  77                 this.engine = engine;
  78                 this.directory = directory;
  79         }
  80
  81         //
  82         // ABSTRACTEXECUTIONTHREADSERVICE METHODS
  83         //
  84
  85         /**
  86          * {@inheritDoc}
  87          */
  88         @Override
  89         protected void run() throws Exception {
  90
  91                 /* loaded chains. */
  92                 final Map<String, Chain> loadedChains = new HashMap<String, Chain>();
  93
  94                 while (isRunning()) {
  95
  96                         /* check if directory is there. */
  97                         File directoryFile = new File(directory);
  98                         if (!directoryFile.exists() || !directoryFile.isDirectory() || !directoryFile.canRead()) {
  99                                 Uninterruptibles.sleepUninterruptibly(1, TimeUnit.SECONDS);
 100                                 continue;
 101                         }
 102
 103                         /* list all files, scan for configuration files. */
 104                         logger.debug(String.format("Scanning %s...", directory));
 105                         File[] configurationFiles = directoryFile.listFiles(new FilenameFilter() {
 106
 107                                 @Override
 108                                 public boolean accept(File dir, String name) {
 109                                         return name.endsWith(".json");
 110                                 }
 111                         });
 112                         logger.debug(String.format("Found %d configuration file(s), parsing...", configurationFiles.length));
 113
 114                         /* now parse all XML files. */
 115                         Map<String, Chain> chains = new HashMap<String, Chain>();
 116                         for (File configurationFile : configurationFiles) {
 117
 118                                 /* parse XML file. */
 119                                 Chain chain = parseConfigurationFile(configurationFile);
 120                                 if (chain == null) {
 121                                         logger.warn(String.format("Could not parse %s.", configurationFile));
 122                                         continue;
 123                                 }
 124
 125                                 /* dump chain */
 126                                 logger.debug(String.format(" Enabled: %s", chain.enabled()));
 127
 128                                 logger.debug(String.format(" Query: %s", chain.query().name()));
 129                                 for (Parameter parameter : chain.query().parameters()) {
 130                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 131                                 }
 132                                 for (Part filter : chain.filters()) {
 133                                         logger.debug(String.format(" Filter: %s", filter.name()));
 134                                         for (Parameter parameter : filter.parameters()) {
 135                                                 logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 136                                         }
 137                                 }
 138                                 logger.debug(String.format(" Trigger: %s", chain.trigger().name()));
 139                                 for (Parameter parameter : chain.trigger().parameters()) {
 140                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 141                                 }
 142                                 logger.debug(String.format(" Action: %s", chain.action().name()));
 143                                 for (Parameter parameter : chain.action().parameters()) {
 144                                         logger.debug(String.format("  Parameter: %s=%s", parameter.name(), parameter.value()));
 145                                 }
 146
 147                                 chains.put(getReactionName(configurationFile.getName()), chain);
 148                         }
 149
 150                         /* filter enabled chains. */
 151                         Map<String, Chain> enabledChains = Maps.filterEntries(chains, new Predicate<Entry<String, Chain>>() {
 152
 153                                 @Override
 154                                 public boolean apply(Entry<String, Chain> chainEntry) {
 155                                         return chainEntry.getValue().enabled();
 156                                 }
 157                         });
 158                         logger.debug(String.format("Found %d enabled Chain(s).", enabledChains.size()));
 159
 160                         /* check for removed chains. */
 161                         Set<String> chainsToRemove = new HashSet<String>();
 162                         for (Entry<String, Chain> loadedChain : loadedChains.entrySet()) {
 163
 164                                 /* skip chains that still exist. */
 165                                 if (enabledChains.containsKey(loadedChain.getKey())) {
 166                                         continue;
 167                                 }
 168
 169                                 logger.info(String.format("Removing Chain: %s", loadedChain.getKey()));
 170                                 engine.removeReaction(loadedChain.getKey());
 171                                 chainsToRemove.add(loadedChain.getKey());
 172                         }
 173
 174                         /* remove removed chains from loaded chains. */
 175                         for (String reactionName : chainsToRemove) {
 176                                 loadedChains.remove(reactionName);
 177                         }
 178
 179                         /* check for new chains. */
 180                         for (Entry<String, Chain> enabledChain : enabledChains.entrySet()) {
 181
 182                                 /* skip already loaded chains. */
 183                                 if (loadedChains.containsValue(enabledChain.getValue())) {
 184                                         continue;
 185                                 }
 186
 187                                 logger.info(String.format("Loading new Chain: %s", enabledChain.getKey()));
 188
 189                                 Reaction reaction = reactionLoader.loadReaction(enabledChain.getValue());
 190                                 engine.addReaction(enabledChain.getKey(), reaction);
 191                                 loadedChains.put(enabledChain.getKey(), enabledChain.getValue());
 192                         }
 193
 194                         /* wait before checking again. */
 195                         Uninterruptibles.sleepUninterruptibly(5, TimeUnit.SECONDS);
 196                 }
 197         }
 198
 199         //
 200         // STATIC METHODS
 201         //
 202
 203         /**
 204          * Parses the given configuration file into a {@link Chain}.
 205          *
 206          * @param configurationFile
 207          *            The configuration file to parse
 208          * @return The parsed chain
 209          */
 210         private static Chain parseConfigurationFile(File configurationFile) {
 211                 try {
 212                         return objectMapper.readValue(configurationFile, Chain.class);
 213                 } catch (JsonParseException jpe1) {
 214                         logger.warn(String.format("Could not parse %s.", configurationFile), jpe1);
 215                 } catch (JsonMappingException jme1) {
 216                         logger.warn(String.format("Could not parse %s.", configurationFile), jme1);
 217                 } catch (IOException ioe1) {
 218                         logger.info(String.format("Could not read %s.", configurationFile));
 219                 }
 220                 return null;
 221         }
 222
 223         /**
 224          * Extracts the name of the reaction from the given filename.
 225          *
 226          * @param filename
 227          *            The filename to extract the reaction name from
 228          * @return The name of the reaction
 229          */
 230         private static String getReactionName(String filename) {
 231                 return (filename.lastIndexOf(".") > -1) ? filename.substring(0, filename.lastIndexOf(".")) : filename;
 232         }
 233
 234 }