java/src/main/com/google/apphosting/utils/config/ClassPathBuilder.java

   1 package com.google.apphosting.utils.config;
   2
   3 import com.google.apphosting.utils.config.AppEngineWebXml.ClassLoaderConfig;
   4 import com.google.apphosting.utils.config.AppEngineWebXml.PrioritySpecifierEntry;
   5 import com.google.common.collect.ImmutableList;
   6
   7 import java.io.File;
   8 import java.net.URL;
   9 import java.util.Arrays;
  10 import java.util.Collection;
  11 import java.util.Comparator;
  12 import java.util.LinkedHashSet;
  13 import java.util.List;
  14 import java.util.Set;
  15 import java.util.regex.Pattern;
  16
  17 /**
  18  * Applies class loader configuration rules to class path {@link URL URLs}.
  19  */
  20 public class ClassPathBuilder {
  21   private static final Pattern CLASSES_REGEX = Pattern.compile(".*/classes/?");
  22
  23   private static final Pattern APPENGINE_API_REGEX =
  24       Pattern.compile(".*/appengine-api(-?[0-9\\.]*-sdk-[0-9\\.]*)?\\.jar");
  25
  26   private static class UrlPriority {
  27     final URL url;
  28     final double priority;
  29
  30     UrlPriority(URL url, double priority) {
  31       this.url = url;
  32       this.priority = priority;
  33     }
  34
  35     @Override
  36     public int hashCode() {
  37       final int prime = 31;
  38       int result = 1;
  39       result = prime * result + ((url == null) ? 0 : url.hashCode());
  40       return result;
  41     }
  42
  43     @Override
  44     public boolean equals(Object obj) {
  45       if (this == obj) return true;
  46       if (obj == null) return false;
  47       if (getClass() != obj.getClass()) return false;
  48       UrlPriority other = (UrlPriority) obj;
  49       if (url == null) {
  50         if (other.url != null) return false;
  51       } else if (!url.equals(other.url)) return false;
  52       return true;
  53     }
  54   }
  55
  56   private static final Comparator<UrlPriority> URL_PRIORITY_COMP = new Comparator<UrlPriority>() {
  57       @Override
  58       public int compare(UrlPriority o1, UrlPriority o2) {
  59         double diff = o1.priority - o2.priority;
  60         if (diff < 0) {
  61           return 1;
  62         }
  63         if (diff > 0) {
  64           return -1;
  65         }
  66         return 0;
  67       }
  68     };
  69
  70   private Set<UrlPriority> urls = new LinkedHashSet<UrlPriority>();
  71
  72   private final List<PrioritySpecifierEntry> priorityEntries;
  73
  74   private final boolean[] usedPrioritySpecifiers;
  75
  76   private URL[] sortedUrls = null;
  77
  78   /**
  79    * @param classLoaderConfig The class loader config, may be null.
  80    */
  81   public ClassPathBuilder(ClassLoaderConfig classLoaderConfig) {
  82     if (classLoaderConfig == null) {
  83       priorityEntries = ImmutableList.of();
  84     } else {
  85       priorityEntries = classLoaderConfig.getEntries();
  86     }
  87     usedPrioritySpecifiers = new boolean[priorityEntries.size()];
  88   }
  89
  90   private void addUrl(URL url, double defaultPriority) {
  91     if (sortedUrls != null) {
  92       throw new IllegalStateException("add* calls are not allowed after getUrls() has been called");
  93     }
  94     Double priority = findPriority(url);
  95     urls.add(new UrlPriority(url, null == priority ? defaultPriority : priority));
  96   }
  97
  98   private Double findPriority(URL url) {
  99     String fileName = new File(url.getPath()).getName();
 100
 101     for (int i = 0; i < usedPrioritySpecifiers.length; ++i) {
 102       if (priorityEntries.get(i).getFilename().equals(fileName)) {
 103         usedPrioritySpecifiers[i] = true;
 104         return priorityEntries.get(i).getPriorityValue();
 105       }
 106     }
 107     return null;
 108   }
 109
 110   /**
 111    * Add the classes {@link URL URLs}.
 112    */
 113   public void addClassesUrl(URL url) {
 114     addUrl(url, 100.0d);
 115   }
 116
 117   /**
 118    * Add the appengine-api.jar {@link URL URLs}.
 119    */
 120   public void addAppengineJar(URL url) {
 121     addUrl(url, 0.5d);
 122   }
 123
 124   /**
 125    * Add application specific jar {@link URL URLs}.
 126    */
 127   public void addAppJar(URL url) {
 128     addUrl(url, 0.0d);
 129   }
 130
 131   /**
 132    * Returns the class loader urls in the order modified by the priority
 133    * specifiers in the {@link ClassLoaderConfig} passed to the constructor.
 134    */
 135   public URL[] getUrls() {
 136     if (sortedUrls == null) {
 137       UrlPriority[] classPath = urls.toArray(new UrlPriority[urls.size()]);
 138       Arrays.sort(classPath, URL_PRIORITY_COMP);
 139
 140       sortedUrls = new URL[classPath.length];
 141       for (int i = 0; i < classPath.length; ++i) {
 142         sortedUrls[i] = classPath[i].url;
 143       }
 144     }
 145     return sortedUrls;
 146   }
 147
 148   /**
 149    * Returns a log message if there were unused specifiers or an empty string.
 150    * <p>Must be called after calling {@link #getUrls()}.
 151    */
 152   public String getLogMessage() {
 153     if (sortedUrls == null) {
 154       throw new IllegalStateException(
 155           "Cannot call getLogMessage() without first calling getUrls()");
 156     }
 157     StringBuilder builder = new StringBuilder();
 158     for (int i = 0; i < usedPrioritySpecifiers.length; ++i) {
 159       if (!usedPrioritySpecifiers[i]) {
 160         builder.append("priority-specifier: filename: ");
 161         builder.append(priorityEntries.get(i).getFilename());
 162         if (priorityEntries.get(i).getPriority() != null) {
 163           builder.append(" priority: ");
 164           builder.append(priorityEntries.get(i).getPriorityValue());
 165         }
 166       }
 167     }
 168     String errors = builder.toString();
 169     if (!errors.isEmpty()) {
 170       return
 171           "appengine-web.xml contains unused class-loader-config priority-specifier values.\n" +
 172           "unused values: " + errors + "\nresulting classpath: " + Arrays.toString(sortedUrls) +
 173           "\nTo remove this warning, remove the unused priority-specifier values " +
 174           "from appengine-web.xml or add a file matching the unused priority-specifier values.";
 175     }
 176     return "";
 177   }
 178
 179   /**
 180    * Scans through a collection of URLs for various patterns and adds them
 181    * with the correct priority.
 182    */
 183   public void addUrls(Collection<URL> urls) {
 184     for (URL url : urls) {
 185       if (CLASSES_REGEX.matcher(url.getPath()).matches()) {
 186         addClassesUrl(url);
 187       } else if (APPENGINE_API_REGEX.matcher(url.getPath()).matches()) {
 188         addAppengineJar(url);
 189       } else {
 190         addAppJar(url);
 191       }
 192     }
 193   }
 194 }