| 1 | /******************************************************************************* |
| 2 | * Copyright (c) 2013, 2014 Ericsson |
| 3 | * All rights reserved. This program and the accompanying materials are |
| 4 | * made available under the terms of the Eclipse Public License v1.0 which |
| 5 | * accompanies this distribution, and is available at |
| 6 | * http://www.eclipse.org/legal/epl-v10.html |
| 7 | * |
| 8 | * Contributors: |
| 9 | * Alexandre Montplaisir - Initial API and implementation |
| 10 | *******************************************************************************/ |
| 11 | |
| 12 | package org.eclipse.tracecompass.internal.tmf.core.statesystem.backends.partial; |
| 13 | |
| 14 | import java.util.List; |
| 15 | import java.util.concurrent.CountDownLatch; |
| 16 | import java.util.concurrent.locks.Lock; |
| 17 | import java.util.concurrent.locks.ReentrantLock; |
| 18 | |
| 19 | import org.eclipse.jdt.annotation.NonNull; |
| 20 | import org.eclipse.tracecompass.internal.statesystem.core.AttributeTree; |
| 21 | import org.eclipse.tracecompass.internal.statesystem.core.StateSystem; |
| 22 | import org.eclipse.tracecompass.statesystem.core.ITmfStateSystem; |
| 23 | import org.eclipse.tracecompass.statesystem.core.backend.StateHistoryBackendFactory; |
| 24 | import org.eclipse.tracecompass.statesystem.core.exceptions.AttributeNotFoundException; |
| 25 | import org.eclipse.tracecompass.statesystem.core.interval.ITmfStateInterval; |
| 26 | |
| 27 | /** |
| 28 | * State system interface-like extension to use with partial state histories. |
| 29 | * |
| 30 | * It mainly exposes the {@link #replaceOngoingState} method, which allows |
| 31 | * seeking the state system to a different point by updating its "ongoing" state |
| 32 | * values. |
| 33 | * |
| 34 | * @author Alexandre Montplaisir |
| 35 | */ |
| 36 | @SuppressWarnings("restriction") /* We're using AttributeTree directly */ |
| 37 | public class PartialStateSystem extends StateSystem { |
| 38 | |
| 39 | private static final String ERR_MSG = "Partial state system should not modify the attribute tree!"; //$NON-NLS-1$ |
| 40 | |
| 41 | private final CountDownLatch ssAssignedLatch = new CountDownLatch(1); |
| 42 | private final Lock queryLock = new ReentrantLock(); |
| 43 | |
| 44 | /** |
| 45 | * Reference to the real upstream state system. This is used so we can read |
| 46 | * its attribute tree. |
| 47 | */ |
| 48 | private StateSystem realStateSystem = null; |
| 49 | |
| 50 | /** |
| 51 | * Constructor |
| 52 | */ |
| 53 | public PartialStateSystem() { |
| 54 | /* |
| 55 | * We use a Null back end here : we only use this state system for its |
| 56 | * "ongoing" values, so no need to save the changes that are inserted. |
| 57 | */ |
| 58 | super(StateHistoryBackendFactory.createNullBackend("partial")); //$NON-NLS-1$ |
| 59 | } |
| 60 | |
| 61 | /** |
| 62 | * Assign the upstream state system to this one. |
| 63 | * |
| 64 | * @param ss |
| 65 | * The real state system |
| 66 | */ |
| 67 | public void assignUpstream(StateSystem ss) { |
| 68 | realStateSystem = ss; |
| 69 | ssAssignedLatch.countDown(); |
| 70 | } |
| 71 | |
| 72 | ITmfStateSystem getUpstreamSS() { |
| 73 | return realStateSystem; |
| 74 | } |
| 75 | |
| 76 | // ------------------------------------------------------------------------ |
| 77 | // Publicized non-API methods |
| 78 | // ------------------------------------------------------------------------ |
| 79 | |
| 80 | @Override |
| 81 | public void replaceOngoingState(List<@NonNull ITmfStateInterval> ongoingIntervals) { |
| 82 | super.replaceOngoingState(ongoingIntervals); |
| 83 | } |
| 84 | |
| 85 | @Override |
| 86 | public synchronized void dispose() { |
| 87 | super.dispose(); |
| 88 | } |
| 89 | |
| 90 | // ------------------------------------------------------------------------ |
| 91 | // Methods regarding the query lock |
| 92 | // ------------------------------------------------------------------------ |
| 93 | |
| 94 | /** |
| 95 | * Take this inner state system's lock before doing a query. |
| 96 | * |
| 97 | * When doing queries, you should take the lock, then run |
| 98 | * {@link #replaceOngoingState}, then send events to its state provider |
| 99 | * input to cause state changes, and then call {@link #queryOngoingState} to |
| 100 | * get the states at the new "current time". |
| 101 | * |
| 102 | * Only after all that it would be safe to release the lock. |
| 103 | */ |
| 104 | public void takeQueryLock() { |
| 105 | try { |
| 106 | queryLock.lockInterruptibly(); |
| 107 | } catch (InterruptedException e) { |
| 108 | e.printStackTrace(); |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | /** |
| 113 | * Release the query lock, when you are done with your query. |
| 114 | */ |
| 115 | public void releaseQueryLock() { |
| 116 | queryLock.unlock(); |
| 117 | } |
| 118 | |
| 119 | @Override |
| 120 | public AttributeTree getAttributeTree() { |
| 121 | waitUntilReady(); |
| 122 | return realStateSystem.getAttributeTree(); |
| 123 | } |
| 124 | |
| 125 | /* |
| 126 | * Override these methods to make sure we don't try to overwrite the |
| 127 | * "real" upstream attribute tree. |
| 128 | */ |
| 129 | |
| 130 | @Override |
| 131 | public void addEmptyAttribute() { |
| 132 | throw new RuntimeException(ERR_MSG); |
| 133 | } |
| 134 | |
| 135 | @Override |
| 136 | public int getQuarkAbsoluteAndAdd(String... attribute) { |
| 137 | waitUntilReady(); |
| 138 | try { |
| 139 | return realStateSystem.getQuarkAbsolute(attribute); |
| 140 | } catch (AttributeNotFoundException e) { |
| 141 | throw new RuntimeException(ERR_MSG); |
| 142 | } |
| 143 | } |
| 144 | |
| 145 | @Override |
| 146 | public int getQuarkRelativeAndAdd(int startingNodeQuark, String... subPath) { |
| 147 | waitUntilReady(); |
| 148 | try { |
| 149 | return realStateSystem.getQuarkRelative(startingNodeQuark, subPath); |
| 150 | } catch (AttributeNotFoundException e) { |
| 151 | throw new RuntimeException(ERR_MSG); |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | private void waitUntilReady() { |
| 156 | try { |
| 157 | ssAssignedLatch.await(); |
| 158 | } catch (InterruptedException e) { |
| 159 | e.printStackTrace(); |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | } |