bundles/org.simantics.db.impl/src/org/simantics/db/impl/query/ExternalReadEntry.java

   1 /*******************************************************************************\r
   2  * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
   3  * in Industry THTH ry.\r
   4  * All rights reserved. This program and the accompanying materials\r
   5  * are made available under the terms of the Eclipse Public License v1.0\r
   6  * which accompanies this distribution, and is available at\r
   7  * http://www.eclipse.org/legal/epl-v10.html\r
   8  *\r
   9  * Contributors:\r
  10  *     VTT Technical Research Centre of Finland - initial API and implementation\r
  11  *******************************************************************************/\r
  12 package org.simantics.db.impl.query;\r
  13 \r
  14 import java.util.ArrayList;\r
  15 import java.util.LinkedList;\r
  16 \r
  17 import org.simantics.db.impl.graph.ReadGraphImpl;\r
  18 import org.simantics.db.procedure.Procedure;\r
  19 import org.simantics.db.request.ExternalRead;\r
  20 import org.simantics.db.request.RequestFlags;\r
  21 \r
  22 final public class ExternalReadEntry<T> extends CacheEntryBase {\r
  23 \r
  24     final LinkedList<T> items = new LinkedList<T>();\r
  25     \r
  26 //    public ArrayList<Procedure<T>> procs;\r
  27 \r
  28     protected ExternalRead<T> request;\r
  29 \r
  30     @Override\r
  31     int makeHash() {\r
  32         return request.hashCode();\r
  33     }\r
  34     \r
  35     @Override\r
  36     public Object getOriginalRequest() {\r
  37         return request;\r
  38     }\r
  39     \r
  40     @Override\r
  41     public void clearResult(QuerySupport support) {\r
  42     }\r
  43     \r
  44     @Override\r
  45     public void discard() {\r
  46         request.unregistered();\r
  47         request = null;\r
  48         super.discard();\r
  49     }\r
  50     \r
  51     public ExternalReadEntry(ExternalRead<T> request) {\r
  52         assert request != null;\r
  53         this.request = request;\r
  54     }\r
  55     \r
  56     final public void queue(T item) {\r
  57         synchronized(items) {\r
  58                 items.addLast(item);\r
  59                 // TODO: implement flags/logic in ExternalRead to state that all but the latest request result can be evaporated\r
  60                 // In some cases where data is produced really fast this might be necessary but currently this queueing will do.\r
  61         }\r
  62     }\r
  63     \r
  64     final public void addOrSet(QueryProcessor processor, Object item) {\r
  65 \r
  66         try {\r
  67         \r
  68             assert(isPending());\r
  69 \r
  70             ArrayList<Procedure<T>> p = null;\r
  71 \r
  72             synchronized(this) {\r
  73 \r
  74                 setResult(item);\r
  75                 setReady();\r
  76 //                p = procs;\r
  77 //                procs = null;\r
  78 \r
  79             }\r
  80 \r
  81 //            if(p != null)\r
  82 //                for(Procedure proc : p) {\r
  83 //                    proc.execute((T)item);\r
  84 //                }\r
  85 \r
  86         } catch (Throwable t) {\r
  87             t.printStackTrace();\r
  88         }\r
  89         \r
  90     }\r
  91     \r
  92     @Override\r
  93     final public Query getQuery() {\r
  94         \r
  95         return new Query() {\r
  96 \r
  97                         @Override\r
  98                         public void recompute(ReadGraphImpl graph, Object provider, CacheEntry entry) {\r
  99 \r
 100                             final QueryProcessor qp = (QueryProcessor)provider;\r
 101                             synchronized(items) {\r
 102 \r
 103                                 if(entry.isExcepted()) {\r
 104                                         \r
 105                                         // Exception persists\r
 106                                         \r
 107                                 } else {\r
 108                                 \r
 109                                         // Update\r
 110                                         if(!items.isEmpty()) {\r
 111                                                 setResult(items.removeFirst());\r
 112                                         }\r
 113                                         // Reschedule\r
 114                                             if(!items.isEmpty()) {\r
 115                                                 qp.updatePrimitive(request);\r
 116                                             }\r
 117                                             \r
 118                                             setReady();\r
 119                                             \r
 120                                 }\r
 121                                 \r
 122                             }\r
 123                                 \r
 124                         }\r
 125 \r
 126                         @Override\r
 127                         public void removeEntry(QueryProcessor processor) {\r
 128                                 processor.externalReadMap.remove(request);\r
 129                         }\r
 130 \r
 131                         @Override\r
 132                         public int type() {\r
 133                                 return RequestFlags.IMMEDIATE_UPDATE;\r
 134                         }\r
 135                         \r
 136                         @Override\r
 137                         public String toString() {\r
 138                                 if(request == null) return "DISCARDED ExternalRead";\r
 139                                 else return request.toString();\r
 140                         }\r
 141                 \r
 142         };\r
 143         \r
 144     }\r
 145 \r
 146         public void performFromCache(Object procedure) {\r
 147                 \r
 148         Procedure<T> proc = (Procedure<T>)procedure;\r
 149 \r
 150             if(isExcepted()) {\r
 151             \r
 152             proc.exception((Throwable)getResult());\r
 153             \r
 154         } else {\r
 155             \r
 156             proc.execute((T)getResult());\r
 157 \r
 158         }\r
 159                 \r
 160         }\r
 161 \r
 162         @Override\r
 163         public String toString() {\r
 164                 if(request == null) return "DISCARDED ExternalRead " + System.identityHashCode(this);\r
 165                 else return request.toString() + " " + + System.identityHashCode(this);\r
 166         }\r
 167 \r
 168     @Override\r
 169     public void performFromCache(ReadGraphImpl graph, Object provider, Object procedure) {\r
 170         performFromCache(procedure);\r
 171     }\r
 172     \r
 173     @Override\r
 174     public void setReady() {\r
 175         super.setReady();\r
 176     }\r
 177     \r
 178     @Override\r
 179     void prepareRecompute(QuerySupport querySupport) {\r
 180         // Do nothing - the state is already set and cannot be recomputed on demand\r
 181     }\r
 182 \r
 183 }\r