bundles/org.simantics.db.layer0/src/org/simantics/db/layer0/StandardSessionManager.java

   1 package org.simantics.db.layer0;
   2
   3 import java.util.Collection;
   4 import java.util.concurrent.ConcurrentHashMap;
   5
   6 import org.simantics.db.ReadGraph;
   7 import org.simantics.db.common.request.ParametrizedPrimitiveRead;
   8 import org.simantics.db.exception.DatabaseException;
   9 import org.simantics.db.layer0.variable.NodeSupport;
  10 import org.simantics.db.procedure.Listener;
  11
  12 abstract public class StandardSessionManager<Node, Engine extends StandardEngine<Node>> {
  13
  14     private ConcurrentHashMap<String, Listener<StandardRealm<Node,Engine>>> realmListeners = new ConcurrentHashMap<>();
  15     private ConcurrentHashMap<String, StandardRealm<Node,Engine>> REALMS = new ConcurrentHashMap<String, StandardRealm<Node,Engine>>();
  16     private ConcurrentHashMap<String, NodeSupport<Node>> SUPPORTS = new ConcurrentHashMap<String, NodeSupport<Node>>();
  17
  18     // Accessing Realms should be done over ParametrizedPrimitveRead for the
  19     // case if a realm is destroyed and new one is created with the same id than
  20     // the previously deleted one for the listeners to get discarded and new
  21     // registered
  22     private class RealmRequest extends ParametrizedPrimitiveRead<String, StandardRealm<Node, Engine>> {
  23
  24         public RealmRequest(String parameter) {
  25             super(parameter);
  26         }
  27
  28         @Override
  29         public void register(ReadGraph graph, Listener<StandardRealm<Node, Engine>> procedure) {
  30
  31             StandardRealm<Node, Engine> realm = REALMS.get(parameter);
  32             if (realm == null) {
  33                 try {
  34                     realm = createRealmInner(graph, parameter);
  35                 } catch (DatabaseException e) {
  36                     e.printStackTrace();
  37                 }
  38             }
  39
  40             if(procedure.isDisposed()) {
  41                 procedure.execute(realm);
  42                 return;
  43             }
  44
  45             Listener<StandardRealm<Node,Engine>> existing = getOrDisposeListener(parameter);
  46             assert(existing == null);
  47             realmListeners.put(parameter, procedure);
  48             procedure.execute(realm);
  49         }
  50
  51         private StandardRealm<Node,Engine> createRealmInner(ReadGraph graph, String id) throws DatabaseException {
  52             Engine engine = createEngine(graph, id);
  53             StandardRealm<Node,Engine> realm = createRealm(engine, id);
  54             modifyRealms(id, realm);
  55             return realm;
  56         }
  57     }
  58
  59     protected StandardSessionManager() {
  60     }
  61
  62     private Listener<StandardRealm<Node,Engine>> getOrDisposeListener(String key) {
  63         Listener<StandardRealm<Node,Engine>> listener = realmListeners.get(key);
  64         if(listener != null) {
  65             if(listener.isDisposed()) {
  66                 realmListeners.remove(key);
  67             } else {
  68                 return listener;
  69             }
  70         }
  71         return null;
  72     }
  73
  74     private void modifyRealms(String key, StandardRealm<Node,Engine> realm) {
  75         if(realm != null) {
  76             REALMS.put(key, realm);
  77         } else {
  78             REALMS.remove(key);
  79         }
  80         Listener<StandardRealm<Node,Engine>> listener = getOrDisposeListener(key);
  81         if(listener != null) {
  82             listener.execute(realm);
  83         }
  84     }
  85
  86     public NodeSupport<Node> getOrCreateNodeSupport(ReadGraph graph, String id) throws DatabaseException {
  87         synchronized(SUPPORTS) {
  88                 NodeSupport<Node> result = SUPPORTS.get(id);
  89                 if(result == null) {
  90                         StandardRealm<Node,Engine> realm = getOrCreateRealm(graph, id);
  91                         result = new NodeSupport<Node>(realm.getNodeManager());
  92                         SUPPORTS.put(id, result);
  93                 }
  94                 return result;
  95         }
  96     }
  97
  98     public StandardRealm<Node,Engine> getOrCreateRealm(ReadGraph graph, String id) throws DatabaseException {
  99         synchronized(REALMS) {
 100             return graph.syncRequest(new RealmRequest(id));
 101         }
 102     }
 103
 104     protected abstract Engine createEngine(ReadGraph graph, String id) throws DatabaseException;
 105     protected abstract StandardRealm<Node,Engine> createRealm(Engine engine, String id);
 106
 107     public void removeRealm(String id) {
 108         modifyRealms(id, null);
 109         // if node support has been created remove it as well
 110         SUPPORTS.remove(id);
 111     }
 112
 113     public Collection<String> getRealms() {
 114         return REALMS.keySet();
 115     }
 116 }