bundles/org.simantics.db.impl/src/org/simantics/db/impl/BlockingAsyncProcedure.java

   1 /*******************************************************************************
   2  * Copyright (c) 2018 Association for Decentralized Information Management
   3  * in Industry THTH ry.
   4  * All rights reserved. This program and the accompanying materials
   5  * are made available under the terms of the Eclipse Public License v1.0
   6  * which accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *     Semantum Oy - initial API and implementation
  11  *******************************************************************************/
  12 package org.simantics.db.impl;
  13
  14 import org.simantics.db.AsyncReadGraph;
  15 import org.simantics.db.exception.DatabaseException;
  16 import org.simantics.db.impl.graph.BarrierTracing;
  17 import org.simantics.db.impl.graph.ReadGraphImpl;
  18 import org.simantics.db.impl.query.AsyncReadEntry;
  19 import org.simantics.db.impl.query.PendingTaskSupport;
  20 import org.simantics.db.procedure.AsyncProcedure;
  21
  22 public class BlockingAsyncProcedure<Result> implements AsyncProcedure<Result> {
  23
  24     private static final Object NO_RESULT = new Object();
  25
  26     public final Object key;
  27     public final ReadGraphImpl queryGraph;
  28     public final ReadGraphImpl callerGraph;
  29     public final AsyncProcedure<Result> procedure;
  30     public PendingTaskSupport pendingTaskSupport;
  31     public Object result = NO_RESULT;
  32     public Throwable exception = null;
  33
  34     private ReadGraphImpl queryGraph() {
  35         return queryGraph;
  36     }
  37
  38     public BlockingAsyncProcedure(ReadGraphImpl callerGraph, AsyncReadEntry<Result> entry, AsyncProcedure<Result> procedure, Object key, boolean needsToBlock) {
  39
  40         // A new graph for evaluating the query with correct parent and asyncBarrier
  41         queryGraph = callerGraph.withParent(entry, () -> {
  42
  43             dispatchProcedure(queryGraph(), callerGraph, entry, procedure, needsToBlock);
  44
  45         });
  46
  47         queryGraph.asyncBarrier.inc();
  48
  49         this.procedure = procedure;
  50         this.key = key;
  51         this.queryGraph.asyncBarrier.inc();
  52         this.callerGraph = callerGraph;
  53         if (BarrierTracing.BOOKKEEPING) {
  54             BarrierTracing.registerBAP(this);
  55         }
  56     }
  57
  58     @Override
  59     public void execute(AsyncReadGraph graph_, Result result) {
  60
  61         this.result = result;
  62         queryGraph.asyncBarrier.dec();
  63
  64     }
  65
  66     @Override
  67     public void exception(AsyncReadGraph graph_, Throwable t) {
  68
  69         this.exception = t;
  70         queryGraph.asyncBarrier.dec();
  71
  72     }
  73
  74     public void waitBarrier() {
  75         queryGraph.asyncBarrier.waitBarrier(key, queryGraph);
  76     }
  77
  78     public void dec() {
  79
  80         queryGraph.asyncBarrier.dec();
  81
  82     }
  83
  84     @SuppressWarnings("unchecked")
  85     public Result get() throws DatabaseException {
  86
  87         queryGraph.asyncBarrier.waitBarrier(key, queryGraph);
  88
  89         if(exception != null) {
  90             if(exception instanceof DatabaseException) throw (DatabaseException)exception;
  91             throw new DatabaseException(exception);
  92         } else {
  93             return (Result)result;
  94         }
  95
  96     }
  97
  98     @SuppressWarnings("unchecked")
  99     public Result getResult() {
 100         return (Result)result;
 101     }
 102
 103     public Throwable getException() {
 104         return exception;
 105     }
 106
 107     @Override
 108     public String toString() {
 109         return "." + procedure;
 110     }
 111
 112     private void dispatchProcedure(ReadGraphImpl queryGraph, ReadGraphImpl parentGraph, AsyncReadEntry<Result> entry, AsyncProcedure<Result> procedure_, boolean needsToBlock) {
 113
 114         AsyncProcedure<Result> procedure = entry != null ? entry : procedure_;
 115
 116         ReadGraphImpl executeGraph = parentGraph.withParent(parentGraph.parent);
 117         executeGraph.asyncBarrier.inc();
 118         try {
 119             if(procedure != null) {
 120                 procedure.execute(executeGraph, get());
 121             }
 122         } catch (DatabaseException e) {
 123             if(procedure != null) procedure.exception(executeGraph, e);
 124             exception = e;
 125         } catch (Throwable t) {
 126             DatabaseException dbe = new DatabaseException(t);
 127             if(procedure != null) procedure.exception(executeGraph, dbe);
 128             exception = dbe;
 129         } finally {
 130
 131             if (entry != null) {
 132                 assert(entry.isReady());
 133                 // This does not throw
 134                 entry.performFromCache(executeGraph, procedure_);
 135             }
 136
 137             executeGraph.asyncBarrier.dec();
 138             if(needsToBlock)
 139                 executeGraph.asyncBarrier.waitBarrier(procedure, executeGraph);
 140         }
 141
 142         if (BarrierTracing.BOOKKEEPING) {
 143             BarrierTracing.unregisterBAP(this);
 144         }
 145
 146     }
 147
 148 }