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

   1 // Copyright 2009 Google Inc. All Rights Reserved.
   2 package com.google.apphosting.utils.config;
   3
   4 import org.mortbay.xml.XmlParser.Node;
   5
   6 import java.io.InputStream;
   7 import java.util.ArrayList;
   8 import java.util.Stack;
   9
  10 /**
  11  * Creates an {@link QueueXml} instance from
  12  * <appdir>WEB-INF/queue.xml.  If you want to read the configuration
  13  * from a different file, subclass and override {@link #getFilename()}.  If you
  14  * want to read the configuration from something that isn't a file, subclass
  15  * and override {@link #getInputStream()}.
  16  *
  17  */
  18 public class QueueXmlReader extends AbstractConfigXmlReader<QueueXml> {
  19
  20   private static final String FILENAME = "WEB-INF/queue.xml";
  21
  22   private static final String TOTAL_STORAGE_LIMIT_TAG = "total-storage-limit";
  23   private static final String QUEUEENTRIES_TAG = "queue-entries";
  24   private static final String QUEUE_TAG = "queue";
  25   private static final String NAME_TAG = "name";
  26   private static final String RATE_TAG = "rate";
  27   private static final String BUCKET_SIZE = "bucket-size";
  28   private static final String MAX_CONCURRENT_REQUESTS = "max-concurrent-requests";
  29   private static final String MODE_TAG = "mode";
  30
  31   private static final String RETRY_PARAMETERS_TAG = "retry-parameters";
  32   private static final String TASK_RETRY_LIMIT_TAG = "task-retry-limit";
  33   private static final String TASK_AGE_LIMIT_TAG = "task-age-limit";
  34   private static final String MIN_BACKOFF_SECONDS_TAG = "min-backoff-seconds";
  35   private static final String MAX_BACKOFF_SECONDS_TAG = "max-backoff-seconds";
  36   private static final String MAX_DOUBLINGS_TAG = "max-doublings";
  37   private static final String TARGET_TAG = "target";
  38
  39   private static final String ACL_TAG = "acl";
  40   private static final String USER_EMAIL_TAG = "user-email";
  41   private static final String WRITER_EMAIL_TAG = "writer-email";
  42
  43   /**
  44    * Constructs the reader for {@code queue.xml} in a given application directory.
  45    * @param appDir the application directory
  46    */
  47   public QueueXmlReader(String appDir) {
  48     super(appDir, false);
  49   }
  50
  51   /**
  52    * Parses the config file.
  53    * @return A {@link QueueXml} object representing the parsed configuration.
  54    */
  55   public QueueXml readQueueXml() {
  56     return readConfigXml();
  57   }
  58
  59   @Override
  60   protected QueueXml processXml(InputStream is) {
  61     final QueueXml queueXml = new QueueXml();
  62     parse(new ParserCallback() {
  63       boolean firstQueueEntriesTag = true;
  64       boolean firstTotalStorageLimitTag = true;
  65       boolean insideRetryParametersTag = false;
  66       boolean insideAclTag = false;
  67       QueueXml.Entry entry;
  68
  69       @Override
  70       public void newNode(Node node, Stack<Node> ancestors) {
  71         switch (ancestors.size()) {
  72           case 0:
  73             if (QUEUEENTRIES_TAG.equalsIgnoreCase(node.getTag())) {
  74               if (!firstQueueEntriesTag) {
  75                 throw new AppEngineConfigException(getFilename() + " contains multiple <"
  76                     + QUEUEENTRIES_TAG + ">");
  77               }
  78               firstQueueEntriesTag = false;
  79             }
  80             break;
  81
  82           case 1:
  83             if (firstQueueEntriesTag) {
  84               throw new AppEngineConfigException(getFilename() + " does not contain <"
  85                   + QUEUEENTRIES_TAG + ">");
  86             }
  87             if (TOTAL_STORAGE_LIMIT_TAG.equalsIgnoreCase(node.getTag())) {
  88               if (!firstTotalStorageLimitTag) {
  89                 throw new AppEngineConfigException(getFilename() + " contains multiple <"
  90                     + TOTAL_STORAGE_LIMIT_TAG + ">");
  91               }
  92               if (node.size() == 1 && node.get(0) instanceof String) {
  93                 queueXml.setTotalStorageLimit(getString(node));
  94               } else {
  95                 throw new AppEngineConfigException(getFilename() + "has invalid <"
  96                     +TOTAL_STORAGE_LIMIT_TAG + ">");
  97               }
  98               firstTotalStorageLimitTag = false;
  99             } else if (QUEUE_TAG.equalsIgnoreCase(node.getTag())) {
 100               entry = queueXml.addNewEntry();
 101             } else {
 102               throw new AppEngineConfigException(getFilename() + " contains <"
 103                   + node.getTag() + "> instead of <" + QUEUE_TAG + "/> or <" +
 104                   TOTAL_STORAGE_LIMIT_TAG + ">");
 105             }
 106             break;
 107
 108           case 2:
 109             assert(entry != null);
 110             if (NAME_TAG.equalsIgnoreCase(node.getTag())) {
 111               if (node.size() == 1 && node.get(0) instanceof String) {
 112                 entry.setName(getString(node));
 113               } else {
 114                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 115                     + NAME_TAG + ">");
 116               }
 117             } else if (BUCKET_SIZE.equalsIgnoreCase(node.getTag())) {
 118                 if (node.size() == 1 && node.get(0) instanceof String) {
 119                   entry.setBucketSize(getString(node));
 120                 } else {
 121                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 122                       + BUCKET_SIZE + ">");
 123                 }
 124             } else if (RATE_TAG.equalsIgnoreCase(node.getTag())) {
 125                 if (node.size() == 1 && node.get(0) instanceof String) {
 126                   entry.setRate(getString(node));
 127                 } else {
 128                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 129                       + RATE_TAG + ">");
 130                 }
 131             } else if (MAX_CONCURRENT_REQUESTS.equalsIgnoreCase(node.getTag())) {
 132                 if (node.size() == 1 && node.get(0) instanceof String) {
 133                   entry.setMaxConcurrentRequests(getString(node));
 134                 } else {
 135                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 136                       + MAX_CONCURRENT_REQUESTS + ">");
 137                 }
 138             } else if (MODE_TAG.equalsIgnoreCase(node.getTag())) {
 139                 if (node.size() == 1 && node.get(0) instanceof String) {
 140                   entry.setMode(getString(node));
 141                 } else {
 142                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 143                       + MODE_TAG + ">");
 144                 }
 145             } else if (TARGET_TAG.equalsIgnoreCase(node.getTag())) {
 146                 if (node.size() == 1 && node.get(0) instanceof String) {
 147                   entry.setTarget(getString(node));
 148                 } else {
 149                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 150                       + TARGET_TAG + ">");
 151                 }
 152             } else if (RETRY_PARAMETERS_TAG.equalsIgnoreCase(node.getTag())) {
 153                 entry.setRetryParameters(new QueueXml.RetryParameters());
 154                 insideRetryParametersTag = true;
 155                 insideAclTag = false;
 156             } else if (ACL_TAG.equalsIgnoreCase(node.getTag())) {
 157                 entry.setAcl(new ArrayList<QueueXml.AclEntry>());
 158                 insideAclTag = true;
 159                 insideRetryParametersTag = false;
 160             } else {
 161               throw new AppEngineConfigException(getFilename() + " contains unknown <"
 162                   + node.getTag() + "> inside <" + QUEUE_TAG + "/>");
 163             }
 164             break;
 165
 166           case 3:
 167             assert(insideRetryParametersTag ^ insideAclTag);
 168             assert(entry != null);
 169             boolean brokenTag = !(node.size() == 1 && node.get(0) instanceof String);
 170
 171             if (insideRetryParametersTag) {
 172               assert(entry.getRetryParameters() != null);
 173               QueueXml.RetryParameters retryParameters = entry.getRetryParameters();
 174
 175               if (TASK_RETRY_LIMIT_TAG.equalsIgnoreCase(node.getTag())) {
 176                 if (!brokenTag) {
 177                   retryParameters.setRetryLimit(getString(node));
 178                 }
 179               } else if (TASK_AGE_LIMIT_TAG.equalsIgnoreCase(node.getTag())) {
 180                 if (!brokenTag) {
 181                   retryParameters.setAgeLimitSec(getString(node));
 182                 }
 183               } else if (MIN_BACKOFF_SECONDS_TAG.equalsIgnoreCase(node.getTag())) {
 184                 if (!brokenTag) {
 185                   retryParameters.setMinBackoffSec(getString(node));
 186                 }
 187               } else if (MAX_BACKOFF_SECONDS_TAG.equalsIgnoreCase(node.getTag())) {
 188                 if (!brokenTag) {
 189                   retryParameters.setMaxBackoffSec(getString(node));
 190                 }
 191               } else if (MAX_DOUBLINGS_TAG.equalsIgnoreCase(node.getTag())) {
 192                 if (!brokenTag) {
 193                   retryParameters.setMaxDoublings(getString(node));
 194                 }
 195               } else {
 196                 throw new AppEngineConfigException(getFilename() + " contains unknown <"
 197                     + node.getTag() + "> inside <" + RETRY_PARAMETERS_TAG + "/>");
 198               }
 199             }
 200
 201             if (insideAclTag) {
 202               assert(entry.getAcl() != null);
 203               if (USER_EMAIL_TAG.equalsIgnoreCase(node.getTag())) {
 204                 if (!brokenTag) {
 205                   QueueXml.AclEntry acl = new QueueXml.AclEntry();
 206                   acl.setUserEmail(getString(node));
 207                   entry.getAcl().add(acl);
 208                 }
 209               } else if (WRITER_EMAIL_TAG.equalsIgnoreCase(node.getTag())) {
 210                 if (!brokenTag) {
 211                   QueueXml.AclEntry acl = new QueueXml.AclEntry();
 212                   acl.setWriterEmail(getString(node));
 213                   entry.getAcl().add(acl);
 214                 }
 215               } else {
 216                 throw new AppEngineConfigException(getFilename() + " contains unknown <"
 217                     + node.getTag() + "> inside <" + ACL_TAG + "/>");
 218               }
 219             }
 220
 221             if (brokenTag) {
 222               throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 223                   + node.getTag() + ">");
 224             }
 225             break;
 226
 227           default:
 228             throw new AppEngineConfigException(getFilename()
 229                 + " has a syntax error; node <"
 230                 + node.getTag() + "> is too deeply nested to be valid.");
 231         }
 232       }
 233     }, is);
 234     queueXml.validateLastEntry();
 235     return queueXml;
 236   }
 237
 238   @Override
 239   protected String getRelativeFilename() {
 240     return FILENAME;
 241   }
 242
 243 }