001 package de.deepamehta.core.impl;
002
003 import de.deepamehta.core.TopicType;
004 import de.deepamehta.core.AssociationType;
005 import de.deepamehta.core.model.AssociationTypeModel;
006 import de.deepamehta.core.model.TopicTypeModel;
007
008
009 import java.util.HashMap;
010 import java.util.Map;
011 import java.util.logging.Logger;
012
013
014
015 /**
016 * A memory-cache for type definitions: topic types and association types.
017 * <p>
018 * Types are accessed by the {@link get} methods. They are lazy-loaded from the DB.
019 * <p>
020 * This class is internally used by the {@link EmbeddedService}. The plugin developer accesses topic types via the
021 * {@link de.deepamehta.core.service.DeepaMehtaService#getTopicType} core service call.
022 */
023 class TypeCache {
024
025 // ---------------------------------------------------------------------------------------------- Instance Variables
026
027 private Map<String, TopicType> topicTypes = new HashMap(); // key: topic type URI
028 private Map<String, AssociationType> assocTypes = new HashMap(); // key: assoc type URI
029
030 private EmbeddedService dms;
031
032 private EndlessRecursionDetection endlessRecursionDetection = new EndlessRecursionDetection();
033
034 private Logger logger = Logger.getLogger(getClass().getName());
035
036 // ---------------------------------------------------------------------------------------------------- Constructors
037
038 TypeCache(EmbeddedService dms) {
039 this.dms = dms;
040 }
041
042 // ----------------------------------------------------------------------------------------- Package Private Methods
043
044 TopicType getTopicType(String topicTypeUri) {
045 TopicType topicType = topicTypes.get(topicTypeUri);
046 if (topicType == null) {
047 topicType = loadTopicType(topicTypeUri);
048 putTopicType(topicType);
049 }
050 return topicType;
051 }
052
053 AssociationType getAssociationType(String assocTypeUri) {
054 AssociationType assocType = assocTypes.get(assocTypeUri);
055 if (assocType == null) {
056 assocType = loadAssociationType(assocTypeUri);
057 putAssociationType(assocType);
058 }
059 return assocType;
060 }
061
062 // ---
063
064 void putTopicType(TopicType topicType) {
065 topicTypes.put(topicType.getUri(), topicType);
066 }
067
068 void putAssociationType(AssociationType assocType) {
069 assocTypes.put(assocType.getUri(), assocType);
070 }
071
072 // ---
073
074 void removeTopicType(String topicTypeUri) {
075 logger.info("### Removing topic type \"" + topicTypeUri + "\" from type cache");
076 if (topicTypes.remove(topicTypeUri) == null) {
077 throw new RuntimeException("Topic type \"" + topicTypeUri + "\" not found in type cache");
078 }
079 dms.typeStorage.removeFromTypeCache(topicTypeUri);
080 }
081
082 void removeAssociationType(String assocTypeUri) {
083 logger.info("### Removing association type \"" + assocTypeUri + "\" from type cache");
084 if (assocTypes.remove(assocTypeUri) == null) {
085 throw new RuntimeException("Association type \"" + assocTypeUri + "\" not found in type cache");
086 }
087 dms.typeStorage.removeFromTypeCache(assocTypeUri);
088 }
089
090 // ------------------------------------------------------------------------------------------------- Private Methods
091
092 private TopicType loadTopicType(String topicTypeUri) {
093 try {
094 logger.info("Loading topic type \"" + topicTypeUri + "\"");
095 endlessRecursionDetection.check(topicTypeUri);
096 //
097 TopicTypeModel model = dms.typeStorage.getTopicType(topicTypeUri);
098 return new AttachedTopicType(model, dms);
099 } finally {
100 endlessRecursionDetection.reset(topicTypeUri);
101 }
102 }
103
104 private AssociationType loadAssociationType(String assocTypeUri) {
105 try {
106 logger.info("Loading association type \"" + assocTypeUri + "\"");
107 endlessRecursionDetection.check(assocTypeUri);
108 //
109 AssociationTypeModel model = dms.typeStorage.getAssociationType(assocTypeUri);
110 return new AttachedAssociationType(model, dms);
111 } finally {
112 endlessRecursionDetection.reset(assocTypeUri);
113 }
114 }
115
116 // ---
117
118 private class EndlessRecursionDetection {
119
120 private Map<String, Boolean> loadInProgress = new HashMap();
121
122 private void check(String typeUri) {
123 if (loadInProgress.get(typeUri) != null) {
124 throw new RuntimeException("Endless recursion detected while loading type \"" + typeUri + "\"");
125 }
126 loadInProgress.put(typeUri, true);
127 }
128
129 private void reset(String typeUri) {
130 loadInProgress.remove(typeUri);
131 }
132 }
133 }