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.WriteGraph;
   8 import org.simantics.db.common.request.ParametrizedPrimitiveRead;
   9 import org.simantics.db.exception.DatabaseException;
  10 import org.simantics.db.layer0.variable.NodeSupport;
  11 import org.simantics.db.procedure.Listener;
  12
  13 abstract public class StandardSessionManager<Node, Engine extends StandardEngine<Node>> {
  14
  15     private ConcurrentHashMap<String, Listener<StandardRealm<Node,Engine>>> realmListeners = new ConcurrentHashMap<>();
  16     private ConcurrentHashMap<String, StandardRealm<Node,Engine>> REALMS = new ConcurrentHashMap<String, StandardRealm<Node,Engine>>();
  17     private ConcurrentHashMap<String, NodeSupport<Node>> SUPPORTS = new ConcurrentHashMap<String, NodeSupport<Node>>();
  18
  19     // Accessing Realms should be done over ParametrizedPrimitveRead for the
  20     // case if a realm is destroyed and new one is created with the same id than
  21     // the previously deleted one for the listeners to get discarded and new
  22     // registered
  23     private class RealmRequest extends ParametrizedPrimitiveRead<String, StandardRealm<Node, Engine>> {
  24
  25         public RealmRequest(String parameter) {
  26             super(parameter);
  27         }
  28
  29         @Override
  30         public void register(ReadGraph graph, Listener<StandardRealm<Node, Engine>> procedure) {
  31
  32             StandardRealm<Node, Engine> realm = REALMS.get(parameter);
  33             if (realm == null) {
  34                 try {
  35                     realm = createRealmInner(graph, parameter);
  36                 } catch (DatabaseException e) {
  37                     e.printStackTrace();
  38                 }
  39             }
  40
  41             if(procedure.isDisposed()) {
  42                 procedure.execute(realm);
  43                 return;
  44             }
  45
  46             Listener<StandardRealm<Node,Engine>> existing = getOrDisposeListener(parameter);
  47             assert(existing == null);
  48             realmListeners.put(parameter, procedure);
  49             procedure.execute(realm);
  50         }
  51
  52         private StandardRealm<Node,Engine> createRealmInner(ReadGraph graph, String id) throws DatabaseException {
  53             Engine engine = createEngine(graph, id);
  54             StandardRealm<Node,Engine> realm = createRealm(engine, id);
  55             modifyRealms(id, realm);
  56             return realm;
  57         }
  58     }
  59
  60     protected StandardSessionManager() {
  61     }
  62
  63     private Listener<StandardRealm<Node,Engine>> getOrDisposeListener(String key) {
  64         Listener<StandardRealm<Node,Engine>> listener = realmListeners.get(key);
  65         if(listener != null) {
  66             if(listener.isDisposed()) {
  67                 realmListeners.remove(key);
  68             } else {
  69                 return listener;
  70             }
  71         }
  72         return null;
  73     }
  74
  75     private void modifyRealms(String key, StandardRealm<Node,Engine> realm) {
  76         if(realm != null) {
  77             REALMS.put(key, realm);
  78         } else {
  79             StandardRealm<Node, Engine> removedRealm = REALMS.remove(key);
  80             if (removedRealm != null)
  81                 removedRealm.close();
  82         }
  83         Listener<StandardRealm<Node,Engine>> listener = getOrDisposeListener(key);
  84         if(listener != null) {
  85             listener.execute(realm);
  86         }
  87     }
  88
  89     public NodeSupport<Node> getOrCreateNodeSupport(ReadGraph graph, String id) throws DatabaseException {
  90         synchronized(SUPPORTS) {
  91                 NodeSupport<Node> result = SUPPORTS.get(id);
  92                 if(result == null) {
  93                         StandardRealm<Node,Engine> realm = getOrCreateRealm(graph, id);
  94                         result = new NodeSupport<Node>(realm.getNodeManager());
  95                         SUPPORTS.put(id, result);
  96                 }
  97                 return result;
  98         }
  99     }
 100
 101     public StandardRealm<Node,Engine> getOrCreateRealm(ReadGraph graph, String id) throws DatabaseException {
 102         synchronized(REALMS) {
 103             return graph.syncRequest(new RealmRequest(id));
 104         }
 105     }
 106
 107     protected abstract Engine createEngine(ReadGraph graph, String id) throws DatabaseException;
 108     protected abstract StandardRealm<Node,Engine> createRealm(Engine engine, String id);
 109
 110     public void removeRealm(WriteGraph graph, String id) throws DatabaseException {
 111         modifyRealms(id, null);
 112         // remove listeners from this realm
 113         realmListeners.remove(id);
 114         // if node support has been created remove it as well
 115         NodeSupport<Node> support = SUPPORTS.remove(id);
 116         if (support != null)
 117             support.dispose();
 118     }
 119
 120     public Collection<String> getRealms() {
 121         return REALMS.keySet();
 122     }
 123 }