org.eclipse.linuxtools.tmf.core/src/org/eclipse/linuxtools/tmf/core/trace/ITmfTrace.java

   1 /*******************************************************************************
   2  * Copyright (c) 2009, 2011, 2012 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Francois Chouinard - Initial API and implementation
  11  *   Francois Chouinard - Updated as per TMF Trace Model 1.0
  12  *******************************************************************************/
  13
  14 package org.eclipse.linuxtools.tmf.core.trace;
  15
  16 import org.eclipse.core.resources.IProject;
  17 import org.eclipse.core.resources.IResource;
  18 import org.eclipse.linuxtools.tmf.core.component.ITmfDataProvider;
  19 import org.eclipse.linuxtools.tmf.core.event.ITmfEvent;
  20 import org.eclipse.linuxtools.tmf.core.event.ITmfTimestamp;
  21 import org.eclipse.linuxtools.tmf.core.event.TmfTimeRange;
  22 import org.eclipse.linuxtools.tmf.core.exceptions.TmfTraceException;
  23
  24 /**
  25  * The event stream structure in TMF. In its basic form, a trace has:
  26  * <ul>
  27  * <li> an associated Eclipse resource
  28  * <li> a path to its location on the file system
  29  * <li> the type of the events it contains
  30  * <li> the number of events it contains
  31  * <li> the time range (span) of the events it contains
  32  * </ul>
  33  * Concrete ITmfTrace classes have to provide a parameter-less constructor and
  34  * an initialization method (<i>initTrace</i>) if they are to be opened from
  35  * the Project View. Also, a validation method (<i>validate</i>) has to be
  36  * provided to ensure that the trace is of the correct type.
  37  * <p>
  38  * A trace can be accessed simultaneously from multiple threads by various
  39  * application components. To avoid obvious multi-threading issues, the trace
  40  * uses an ITmfContext as a synchronization aid for its read operations.
  41  * <p>
  42  * A proper ITmfContext can be obtained by performing a seek operation on the
  43  * trace. Seek operations can be performed for a particular event (by rank or
  44  * timestamp) or for a plain trace location.
  45  * <p>
  46  * <b>Example 1</b>: Process a whole trace
  47  * <pre>
  48  * ITmfContext context = trace.seekEvent(0);
  49  * ITmfEvent event = trace.getNext(context);
  50  * while (event != null) {
  51  *     processEvent(event);
  52  *     event = trace.getNext(context);
  53  * }
  54  * </pre>
  55  * <b>Example 2</b>: Process 50 events starting from the 1000th event
  56  * <pre>
  57  * int nbEventsRead = 0;
  58  * ITmfContext context = trace.seekEvent(1000);
  59  * ITmfEvent event = trace.getNext(context);
  60  * while (event != null && nbEventsRead < 50) {
  61  *     nbEventsRead++;
  62  *     processEvent(event);
  63  *     event = trace.getNext(context);
  64  * }
  65  * </pre>
  66  * <b>Example 3</b>: Process the events between 2 timestamps (inclusive)
  67  * <pre>
  68  * ITmfTimestamp startTime = ...;
  69  * ITmfTimestamp endTime = ...;
  70  * ITmfContext context = trace.seekEvent(startTime);
  71  * ITmfEvent event = trace.getNext(context);
  72  * while (event != null && event.getTimestamp().compareTo(endTime) <= 0) {
  73  *     processEvent(event);
  74  *     event = trace.getNext(context);
  75  * }
  76  * </pre>
  77  * A trace is also an event provider so it can process event requests
  78  * asynchronously (and coalesce compatible, concurrent requests).
  79  * <p>
  80  * </pre>
  81  * <b>Example 4</b>: Process a whole trace (see ITmfEventRequest for variants)
  82  * <pre>
  83  * ITmfRequest request = new TmfEventRequest&lt;MyEventType&gt;(MyEventType.class) {
  84  *     &#64;Override
  85  *     public void handleData(MyEventType event) {
  86  *         super.handleData(event);
  87  *         processEvent(event);
  88  *     }
  89  *     &#64;Override
  90  *     public void handleCompleted() {
  91  *         finish();
  92  *         super.handleCompleted();
  93  *     }
  94  * };
  95  *
  96  * fTrace.handleRequest(request);
  97  * if (youWant) {
  98  *     request.waitForCompletion();
  99  * }
 100  * </pre>
 101  *
 102  * @version 1.0
 103  * @author Francois Chouinard
 104  *
 105  * @see ITmfContext
 106  * @see ITmfEvent
 107  * @see ITmfTraceIndexer
 108  * @see ITmfEventParser
 109  */
 110 public interface ITmfTrace extends ITmfDataProvider {
 111
 112     // ------------------------------------------------------------------------
 113     // Constants
 114     // ------------------------------------------------------------------------
 115
 116     /**
 117      * The default trace cache size
 118      */
 119     public static final int DEFAULT_TRACE_CACHE_SIZE = 1000;
 120
 121     // ------------------------------------------------------------------------
 122     // Initializers
 123     // ------------------------------------------------------------------------
 124
 125     /**
 126      * Initialize a newly instantiated "empty" trace object. This is used to
 127      * properly parameterize an ITmfTrace instantiated with its parameterless
 128      * constructor.
 129      * <p>
 130      * Typically, the parameterless constructor will provide the block size
 131      * and its associated parser and indexer.
 132      *
 133      * @param resource the trace resource
 134      * @param path the trace path
 135      * @param type the trace event type
 136      * @throws TmfTraceException If we couldn't open the trace
 137      */
 138     public void initTrace(IResource resource, String path, Class<? extends ITmfEvent> type) throws TmfTraceException;
 139
 140     /**
 141      * Validate that the trace is of the correct type.
 142      *
 143      * @param project the eclipse project
 144      * @param path the trace path
 145      *
 146      * @return true if trace is valid
 147      */
 148     public boolean validate(IProject project, String path);
 149
 150     // ------------------------------------------------------------------------
 151     // Basic getters
 152     // ------------------------------------------------------------------------
 153
 154     /**
 155      * @return the trace event type
 156      */
 157     public Class<? extends ITmfEvent> getEventType();
 158
 159     /**
 160      * @return the associated trace resource
 161      */
 162     public IResource getResource();
 163
 164     /**
 165      * @return the trace path
 166      */
 167     public String getPath();
 168
 169     /**
 170      * @return the trace cache size
 171      */
 172     public int getCacheSize();
 173
 174     // ------------------------------------------------------------------------
 175     // Trace characteristics getters
 176     // ------------------------------------------------------------------------
 177
 178     /**
 179      * @return the number of events in the trace
 180      */
 181     public long getNbEvents();
 182
 183     /**
 184      * @return the trace time range
 185      */
 186     public TmfTimeRange getTimeRange();
 187
 188     /**
 189      * @return the timestamp of the first trace event
 190      */
 191     public ITmfTimestamp getStartTime();
 192
 193     /**
 194      * @return the timestamp of the last trace event
 195      */
 196     public ITmfTimestamp getEndTime();
 197
 198     /**
 199      * @return the streaming interval in ms (0 if not a streaming trace)
 200      */
 201     public long getStreamingInterval();
 202
 203     // ------------------------------------------------------------------------
 204     // Trace positioning getters
 205     // ------------------------------------------------------------------------
 206
 207     /**
 208      * @return the current trace location
 209      */
 210     public ITmfLocation getCurrentLocation();
 211
 212     /**
 213      * Returns the ratio (proportion) corresponding to the specified location.
 214      *
 215      * @param location a trace specific location
 216      * @return a floating-point number between 0.0 (beginning) and 1.0 (end)
 217      */
 218     public double getLocationRatio(ITmfLocation location);
 219
 220     // ------------------------------------------------------------------------
 221     // SeekEvent operations (returning a trace context)
 222     // ------------------------------------------------------------------------
 223
 224     /**
 225      * Position the trace at the specified (trace specific) location.
 226      * <p>
 227      * A null location is interpreted as seeking for the first event of the
 228      * trace.
 229      * <p>
 230      * If not null, the location requested must be valid otherwise the returned
 231      * context is undefined (up to the implementation to recover if possible).
 232      * <p>
 233      * @param location the trace specific location
 234      * @return a context which can later be used to read the corresponding event
 235      */
 236     public ITmfContext seekEvent(ITmfLocation location);
 237
 238     /**
 239      * Position the trace at the 'rank'th event in the trace.
 240      * <p>
 241      * A rank <= 0 is interpreted as seeking for the first event of the
 242      * trace.
 243      * <p>
 244      * If the requested rank is beyond the last trace event, the context
 245      * returned will yield a null event if used in a subsequent read.
 246      *
 247      * @param rank the event rank
 248      * @return a context which can later be used to read the corresponding event
 249      */
 250     public ITmfContext seekEvent(long rank);
 251
 252     /**
 253      * Position the trace at the first event with the specified timestamp. If
 254      * there is no event with the requested timestamp, a context pointing to
 255      * the next chronological event is returned.
 256      * <p>
 257      * A null timestamp is interpreted as seeking for the first event of the
 258      * trace.
 259      * <p>
 260      * If the requested timestamp is beyond the last trace event, the context
 261      * returned will yield a null event if used in a subsequent read.
 262      *
 263      * @param timestamp the timestamp of desired event
 264      * @return a context which can later be used to read the corresponding event
 265      */
 266     public ITmfContext seekEvent(ITmfTimestamp timestamp);
 267
 268     /**
 269      * Position the trace at the event located at the specified ratio in the
 270      * trace file.
 271      * <p>
 272      * The notion of ratio (0.0 <= r <= 1.0) is trace specific and left
 273      * voluntarily vague. Typically, it would refer to the event proportional
 274      * rank (arguably more intuitive) or timestamp in the trace file.
 275      *
 276      * @param ratio the proportional 'rank' in the trace
 277      * @return a context which can later be used to read the corresponding event
 278      */
 279     public ITmfContext seekEvent(double ratio);
 280
 281 }