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

   1 // Copyright 2008 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.Stack;
   8
   9 /**
  10  * Creates an {@link CronXml} instance from
  11  * <appdir>WEB-INF/cron.xml.  If you want to read the configuration
  12  * from a different file, subclass and override {@link #getFilename()}.  If you
  13  * want to read the configuration from something that isn't a file, subclass
  14  * and override {@link #getInputStream()}.
  15  *
  16  */
  17 public class CronXmlReader extends AbstractConfigXmlReader<CronXml> {
  18
  19   private static final String FILENAME = "WEB-INF/cron.xml";
  20
  21   private static final String CRONENTRIES_TAG = "cronentries";
  22   private static final String CRON_TAG = "cron";
  23   private static final String DESCRIPTION_TAG = "description";
  24   private static final String SCHEDULE_TAG = "schedule";
  25   private static final String TARGET_TAG = "target";
  26   private static final String TIMEZONE_TAG = "timezone";
  27   private static final String URL_TAG = "url";
  28   private static final String RETRY_PARAMETERS_TAG = "retry-parameters";
  29   private static final String JOB_RETRY_LIMIT_TAG = "job-retry-limit";
  30   private static final String JOB_AGE_LIMIT_TAG = "job-age-limit";
  31   private static final String MIN_BACKOFF_SECONDS_TAG = "min-backoff-seconds";
  32   private static final String MAX_BACKOFF_SECONDS_TAG = "max-backoff-seconds";
  33   private static final String MAX_DOUBLINGS_TAG = "max-doublings";
  34
  35   /**
  36    * Constructs the reader for {@code cron.xml} in a given application directory.
  37    * @param appDir the application directory
  38    */
  39   public CronXmlReader(String appDir) {
  40     super(appDir, false);
  41   }
  42
  43   /**
  44    * Parses the config file.
  45    * @return A {@link CronXml} object representing the parsed configuration.
  46    */
  47   public CronXml readCronXml() {
  48     return readConfigXml();
  49   }
  50
  51   @Override
  52   protected CronXml processXml(InputStream is) {
  53     final CronXml cronXml = new CronXml();
  54     parse(new ParserCallback() {
  55       boolean first = true;
  56       CronXml.Entry entry;
  57       boolean insideRetryParametersTag = false;
  58
  59       @Override
  60       public void newNode(Node node, Stack<Node> ancestors) {
  61         switch (ancestors.size()) {
  62           case 0:
  63             if (!CRONENTRIES_TAG.equalsIgnoreCase(node.getTag())) {
  64               throw new AppEngineConfigException(getFilename() + " does not contain <"
  65                   + CRONENTRIES_TAG + ">");
  66             }
  67             if (!first) {
  68               throw new AppEngineConfigException(getFilename() + " contains multiple <"
  69                   + CRONENTRIES_TAG + ">");
  70             }
  71             first = false;
  72             break;
  73
  74           case 1:
  75             if (CRON_TAG.equalsIgnoreCase(node.getTag())) {
  76               entry = cronXml.addNewEntry();
  77             } else {
  78               throw new AppEngineConfigException(getFilename() + " contains <"
  79                   + node.getTag() + "> instead of <" + CRON_TAG + "/>");
  80             }
  81             break;
  82
  83           case 2:
  84             insideRetryParametersTag = false;
  85             assert(entry != null);
  86             if (DESCRIPTION_TAG.equalsIgnoreCase(node.getTag())) {
  87               if (node.size() == 1 && node.get(0) instanceof String) {
  88                 entry.setDescription((String) node.get(0));
  89               } else {
  90                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
  91                     + DESCRIPTION_TAG + ">");
  92               }
  93             } else if (URL_TAG.equalsIgnoreCase(node.getTag())) {
  94                 if (node.size() == 1 && node.get(0) instanceof String) {
  95                   entry.setUrl((String) node.get(0));
  96                 } else {
  97                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
  98                       + URL_TAG + ">");
  99                 }
 100             } else if (SCHEDULE_TAG.equalsIgnoreCase(node.getTag())) {
 101               if (node.size() == 1 && node.get(0) instanceof String) {
 102                 entry.setSchedule((String) node.get(0));
 103               } else {
 104                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 105                     + SCHEDULE_TAG + ">");
 106               }
 107             } else if (TIMEZONE_TAG.equalsIgnoreCase(node.getTag())) {
 108               if (node.size() == 1 && node.get(0) instanceof String) {
 109                 entry.setTimezone((String) node.get(0));
 110               } else {
 111                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 112                     + TIMEZONE_TAG + ">");
 113               }
 114             } else if (TARGET_TAG.equalsIgnoreCase(node.getTag())) {
 115               if (node.size() == 1 && node.get(0) instanceof String) {
 116                 entry.setTarget((String) node.get(0));
 117               } else {
 118                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 119                     + TARGET_TAG + ">");
 120               }
 121             } else if (RETRY_PARAMETERS_TAG.equalsIgnoreCase(node.getTag())) {
 122                 entry.setRetryParameters(new RetryParametersXml());
 123                 insideRetryParametersTag = true;
 124             } else {
 125               throw new AppEngineConfigException(getFilename() + " contains unknown <"
 126                   + node.getTag() + "> inside <" + CRON_TAG + "/>");
 127             }
 128             break;
 129
 130           case 3:
 131             assert(insideRetryParametersTag);
 132             assert(entry != null);
 133             boolean brokenTag = !(node.size() == 1 && node.get(0) instanceof String);
 134
 135             RetryParametersXml retryParameters = entry.getRetryParameters();
 136             assert(entry.getRetryParameters() != null);
 137
 138             if (JOB_RETRY_LIMIT_TAG.equalsIgnoreCase(node.getTag())) {
 139               if (!brokenTag) {
 140                 retryParameters.setRetryLimit(getString(node));
 141               }
 142             } else if (JOB_AGE_LIMIT_TAG.equalsIgnoreCase(node.getTag())) {
 143               if (!brokenTag) {
 144                 retryParameters.setAgeLimitSec(getString(node));
 145               }
 146             } else if (MIN_BACKOFF_SECONDS_TAG.equalsIgnoreCase(node.getTag())) {
 147               if (!brokenTag) {
 148                 retryParameters.setMinBackoffSec(getString(node));
 149               }
 150             } else if (MAX_BACKOFF_SECONDS_TAG.equalsIgnoreCase(node.getTag())) {
 151               if (!brokenTag) {
 152                 retryParameters.setMaxBackoffSec(getString(node));
 153               }
 154             } else if (MAX_DOUBLINGS_TAG.equalsIgnoreCase(node.getTag())) {
 155               if (!brokenTag) {
 156                 retryParameters.setMaxDoublings(getString(node));
 157               }
 158             } else {
 159               throw new AppEngineConfigException(getFilename() + " contains unknown <"
 160                   + node.getTag() + "> inside <" + RETRY_PARAMETERS_TAG + "/>");
 161             }
 162
 163             if (brokenTag) {
 164               throw new AppEngineConfigException(getFilename() + " has bad contents in <"
 165                   + node.getTag() + ">");
 166             }
 167             break;
 168
 169           default:
 170               throw new AppEngineConfigException(getFilename()
 171                   + " has a syntax error; node <"
 172                   + node.getTag() + "> is too deeply nested to be valid.");
 173         }
 174       }
 175     }, is);
 176     cronXml.validateLastEntry();
 177     return cronXml;
 178   }
 179
 180   @Override
 181   protected String getRelativeFilename() {
 182     return FILENAME;
 183   }
 184
 185 }