org.eclipse.tracecompass.statesystem.core/src/org/eclipse/tracecompass/statesystem/core/backend/IStateHistoryBackend.java

   1 /*******************************************************************************
   2  * Copyright (c) 2012, 2014 Ericsson
   3  * Copyright (c) 2010, 2011 École Polytechnique de Montréal
   4  * Copyright (c) 2010, 2011 Alexandre Montplaisir <alexandre.montplaisir@gmail.com>
   5  *
   6  * All rights reserved. This program and the accompanying materials are
   7  * made available under the terms of the Eclipse Public License v1.0 which
   8  * accompanies this distribution, and is available at
   9  * http://www.eclipse.org/legal/epl-v10.html
  10  *
  11  *******************************************************************************/
  12
  13 package org.eclipse.tracecompass.statesystem.core.backend;
  14
  15 import java.io.File;
  16 import java.io.FileInputStream;
  17 import java.io.PrintWriter;
  18 import java.util.List;
  19
  20 import org.eclipse.jdt.annotation.NonNull;
  21 import org.eclipse.tracecompass.statesystem.core.exceptions.AttributeNotFoundException;
  22 import org.eclipse.tracecompass.statesystem.core.exceptions.StateSystemDisposedException;
  23 import org.eclipse.tracecompass.statesystem.core.exceptions.TimeRangeException;
  24 import org.eclipse.tracecompass.statesystem.core.interval.ITmfStateInterval;
  25 import org.eclipse.tracecompass.statesystem.core.statevalue.ITmfStateValue;
  26
  27 /**
  28  * The main difference between StateSystem and StateHistorySystem is that SHS
  29  * allows 'seeking' back in time to reload a Current State at a previous time.
  30  * "How to go back in time" is defined by the implementation of the
  31  * HistoryBackend.
  32  *
  33  * A StateHistorySystem contains one and only one HistoryBackend. If you want to
  34  * use a paradigm with more than one provider (eg. more or less precision
  35  * depending on what's asked by the user), implement one wrapper HistoryBackend
  36  * which can then contain your 2-3 other backends underneath.
  37  *
  38  * @author Alexandre Montplaisir
  39  * @since 3.0
  40  */
  41 public interface IStateHistoryBackend {
  42
  43     /**
  44      * Get the start time of this state history. This is usually the same as the
  45      * start time of the originating trace.
  46      *
  47      * @return The start time
  48      */
  49     long getStartTime();
  50
  51     /**
  52      * Get the current end time of the state history. It will change as the
  53      * history is being built.
  54      *
  55      * @return The end time
  56      */
  57     long getEndTime();
  58
  59     /**
  60      * Main method to insert state intervals into the history.
  61      *
  62      * @param stateStartTime
  63      *            The start time of the interval
  64      * @param stateEndTime
  65      *            The end time of the interval
  66      * @param quark
  67      *            The quark of the attribute this interval refers to
  68      * @param value
  69      *            The StateValue represented by this interval
  70      * @throws TimeRangeException
  71      *             If the start or end time are invalid
  72      */
  73     // FIXME change to IStateInterval?
  74     void insertPastState(long stateStartTime, long stateEndTime,
  75             int quark, ITmfStateValue value) throws TimeRangeException;
  76
  77     /**
  78      * Indicate to the provider that we are done building the history (so it can
  79      * close off, stop threads, etc.)
  80      *
  81      * @param endTime
  82      *            The end time to assign to this state history. It could be
  83      *            farther in time than the last state inserted, for example.
  84      * @throws TimeRangeException
  85      *             If the requested time makes no sense.
  86      */
  87     void finishedBuilding(long endTime) throws TimeRangeException;
  88
  89     /**
  90      * It is the responsibility of the backend to define where to save the
  91      * Attribute Tree (since it's only useful to "reopen" an Attribute Tree if
  92      * we have the matching History).
  93      *
  94      * This method defines where to read for the attribute tree when opening an
  95      * already-existing history. Refer to the file format documentation.
  96      *
  97      * @return A FileInputStream object pointing to the correct file/location in
  98      *         the file where to read the attribute tree information.
  99      */
 100     FileInputStream supplyAttributeTreeReader();
 101
 102     // FIXME change to FOS too?
 103     /**
 104      * Supply the File object to which we will write the attribute tree. The
 105      * position in this file is supplied by -TreeWriterFilePosition.
 106      *
 107      * @return The target File
 108      */
 109     File supplyAttributeTreeWriterFile();
 110
 111     /**
 112      * Supply the position in the file where we should write the attribute tree
 113      * when asked to.
 114      *
 115      * @return The file position (we will seek() to it)
 116      */
 117     long supplyAttributeTreeWriterFilePosition();
 118
 119     /**
 120      * Delete any generated files or anything that might have been created by
 121      * the history backend (either temporary or save files). By calling this, we
 122      * return to the state as it was before ever building the history.
 123      *
 124      * You might not want to call automatically if, for example, you want an
 125      * index file to persist on disk. This could be limited to actions
 126      * originating from the user.
 127      */
 128     void removeFiles();
 129
 130     /**
 131      * Notify the state history back-end that the trace is being closed, so it
 132      * should release its file descriptors, close its connections, etc.
 133      */
 134     void dispose();
 135
 136     // ------------------------------------------------------------------------
 137     // Query methods
 138     // ------------------------------------------------------------------------
 139
 140     /**
 141      * Complete "give me the state at a given time" method 'currentStateInfo' is
 142      * an "out" parameter, that is, write to it the needed information and
 143      * return. DO NOT 'new' currentStateInfo, it will be lost and nothing will
 144      * be returned!
 145      *
 146      * @param currentStateInfo
 147      *            List of StateValues (index == quark) to fill up
 148      * @param t
 149      *            Target timestamp of the query
 150      * @throws TimeRangeException
 151      *             If the timestamp is outside of the history/trace
 152      * @throws StateSystemDisposedException
 153      *             If the state system is disposed while a request is ongoing.
 154      */
 155     void doQuery(@NonNull List<ITmfStateInterval> currentStateInfo, long t)
 156             throws TimeRangeException, StateSystemDisposedException;
 157
 158     /**
 159      * Some providers might want to specify a different way to obtain just a
 160      * single StateValue instead of updating the whole list. If the method to
 161      * use is the same, then feel free to just implement this as a wrapper using
 162      * doQuery().
 163      *
 164      * @param t
 165      *            The target timestamp of the query.
 166      * @param attributeQuark
 167      *            The single attribute for which you want the state interval
 168      * @return The state interval matching this timestamp/attribute pair
 169      * @throws TimeRangeException
 170      *             If the timestamp was invalid
 171      * @throws AttributeNotFoundException
 172      *             If the quark was invalid
 173      * @throws StateSystemDisposedException
 174      *             If the state system is disposed while a request is ongoing.
 175      */
 176     ITmfStateInterval doSingularQuery(long t, int attributeQuark)
 177             throws TimeRangeException, AttributeNotFoundException,
 178             StateSystemDisposedException;
 179
 180     /**
 181      * Debug method to print the contents of the history backend.
 182      *
 183      * @param writer
 184      *            The PrintWriter where to write the output
 185      */
 186     void debugPrint(PrintWriter writer);
 187 }