Mercurial > dive4elements > river
comparison artifacts/src/main/java/org/dive4elements/river/artifacts/D4EArtifact.java @ 8659:af415396d9ca
(issue1803) Use MD5 instead of a homegrown hashing algorithm
For creating a digest of the parametrization we should use an
algorithm that does not create collisions if there are small changes
in the parametrization so that wrong results are returned.
| author | Andre Heinecke <andre.heinecke@intevation.de> |
|---|---|
| date | Thu, 02 Apr 2015 17:40:18 +0200 |
| parents | 7d1a32a543cb |
| children | 5e38e2924c07 |
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| 8658:3531f0cee5e1 | 8659:af415396d9ca |
|---|---|
| 16 import java.util.List; | 16 import java.util.List; |
| 17 import java.util.Map; | 17 import java.util.Map; |
| 18 import java.util.Set; | 18 import java.util.Set; |
| 19 import java.util.TreeMap; | 19 import java.util.TreeMap; |
| 20 | 20 |
| 21 import java.security.MessageDigest; | |
| 22 import java.security.NoSuchAlgorithmException; | |
| 23 import java.io.ByteArrayOutputStream; | |
| 24 import java.io.ObjectOutputStream; | |
| 25 import java.io.IOException; | |
| 26 | |
| 21 import javax.xml.xpath.XPathConstants; | 27 import javax.xml.xpath.XPathConstants; |
| 28 import javax.xml.bind.DatatypeConverter; | |
| 22 | 29 |
| 23 import net.sf.ehcache.Cache; | 30 import net.sf.ehcache.Cache; |
| 24 | 31 |
| 25 import org.apache.log4j.Logger; | 32 import org.apache.log4j.Logger; |
| 26 import org.w3c.dom.Document; | 33 import org.w3c.dom.Document; |
| 1133 * | 1140 * |
| 1134 * @return a hash code. | 1141 * @return a hash code. |
| 1135 */ | 1142 */ |
| 1136 @Override | 1143 @Override |
| 1137 public String hash() { | 1144 public String hash() { |
| 1138 | 1145 try { |
| 1139 long hash = 0L; | 1146 ByteArrayOutputStream ba = new ByteArrayOutputStream(); |
| 1140 int shift = 3; | 1147 ObjectOutputStream oa = new ObjectOutputStream(ba); |
| 1141 | 1148 for (Map.Entry<String, StateData> entry: data.entrySet()) { |
| 1142 for (Map.Entry<String, StateData> entry: data.entrySet()) { | 1149 oa.writeObject(entry.getKey()); |
| 1143 String key = entry.getKey(); | 1150 oa.writeObject(entry.getValue().getValue()); |
| 1144 Object value = entry.getValue().getValue(); | 1151 } |
| 1145 | 1152 MessageDigest md = MessageDigest.getInstance("MD5"); |
| 1146 hash ^= ((long)key.hashCode() << shift) | 1153 byte[] md5sum = md.digest(ba.toByteArray()); |
| 1147 | ((long)value.hashCode() << (shift + 3)); | 1154 return DatatypeConverter.printBase64Binary(md5sum); |
| 1148 shift += 2; | 1155 } catch (NoSuchAlgorithmException e) { |
| 1149 } | 1156 throw new RuntimeException("MD5 unavailable. Can't happen."); |
| 1150 | 1157 } catch (IOException e) { |
| 1151 return getCurrentStateId() + hash; | 1158 throw new RuntimeException("Cant write parameter. Can't happen."); |
| 1159 } | |
| 1152 } | 1160 } |
| 1153 | 1161 |
| 1154 | 1162 |
| 1155 /** | 1163 /** |
| 1156 * Return List of outputs, where combinations of outputname and filtername | 1164 * Return List of outputs, where combinations of outputname and filtername |
| 1507 Object old = null; | 1515 Object old = null; |
| 1508 | 1516 |
| 1509 if (cache != null) { | 1517 if (cache != null) { |
| 1510 net.sf.ehcache.Element element = cache.get(key); | 1518 net.sf.ehcache.Element element = cache.get(key); |
| 1511 if (element != null) { | 1519 if (element != null) { |
| 1512 log.debug("Got computation result from cache."); | 1520 log.debug("Got computation result from cache for key: " + key); |
| 1513 old = element.getValue(); | 1521 old = element.getValue(); |
| 1514 } | 1522 } |
| 1515 } | 1523 } |
| 1516 else { | 1524 else { |
| 1517 log.debug("cache not configured."); | 1525 log.debug("cache not configured."); |