net.mograsim.logic.core/src/net/mograsim/logic/core/timeline/Timeline.java

   1 package net.mograsim.logic.core.timeline;
   2
   3 import java.util.ArrayList;
   4 import java.util.List;
   5 import java.util.PriorityQueue;
   6 import java.util.function.BooleanSupplier;
   7 import java.util.function.Consumer;
   8 import java.util.function.LongSupplier;
   9
  10 /**
  11  * Orders Events by the time they are due to be executed. Can execute Events individually.
  12  *
  13  * @author Fabian Stemmler
  14  *
  15  */
  16 public class Timeline
  17 {
  18         private PriorityQueue<InnerEvent> events;
  19         private LongSupplier time;
  20         private long lastTimeUpdated = 0;
  21
  22         private final List<Consumer<TimelineEvent>> eventAddedListener;
  23
  24         public final LongSupplier stepByStepExec = () -> lastTimeUpdated;
  25         public final LongSupplier realTimeExec = () -> System.currentTimeMillis();
  26
  27         /**
  28          * Constructs a Timeline object. Per default the time function is set to step by step execution.
  29          *
  30          * @param initCapacity The initial capacity of the event queue.
  31          */
  32         public Timeline(int initCapacity)
  33         {
  34                 events = new PriorityQueue<>(initCapacity);
  35                 eventAddedListener = new ArrayList<>();
  36                 time = stepByStepExec;
  37         }
  38
  39         /**
  40          * @param timestamp exclusive
  41          * @return <code>true</code> if the first event in queue is later than the given timestamp
  42          */
  43         public BooleanSupplier laterThan(long timestamp)
  44         {
  45                 return () -> timeCmp(events.peek().getTiming(), timestamp) > 0;
  46         }
  47
  48         /**
  49          * @return <code>true</code> if there is at least one event enqueued. <code>false</code> otherwise
  50          */
  51         public boolean hasNext()
  52         {
  53                 return !events.isEmpty();
  54         }
  55
  56         /**
  57          * Executes all events at the next timestamp, at which there are any
  58          */
  59         public void executeNext()
  60         {
  61                 InnerEvent first = events.peek();
  62                 if (first != null)
  63                         executeUntil(laterThan(first.getTiming()), -1);
  64         }
  65
  66         /**
  67          * Executes all events enqueued in the {@link Timeline}. Use very carefully! Events may generate new events, causing an infinite loop.
  68          */
  69         public void executeAll()
  70         {
  71                 while (hasNext())
  72                         executeNext();
  73         }
  74
  75         /**
  76          * Executes all events until a given condition is met. The simulation process can be constrained by a real world timestamp.
  77          *
  78          * @param condition  the condition until which the events are be processed
  79          * @param stopMillis the System.currentTimeMillis() when simulation definitely needs to stop. A value of -1 means no timeout.
  80          * @return State of the event execution
  81          * @formatter:off
  82          * <code>NOTHING_DONE</code> if the {@link Timeline} was already empty
  83          * <code>EXEC_OUT_OF_TIME</code> if the given maximum time was reached
  84          * <code>EXEC_UNTIL_CONDITION</code> if the condition was met
  85          * <code>EXEC_UNTIL_EMPTY</code> if events were executed until the {@link Timeline} was empty
  86          * @formatter:on
  87          */
  88         public ExecutionResult executeUntil(BooleanSupplier condition, long stopMillis)
  89         {
  90                 if (events.isEmpty())
  91                 {
  92                         lastTimeUpdated = getSimulationTime();
  93                         return ExecutionResult.NOTHING_DONE;
  94                 }
  95                 int checkStop = 0;
  96                 InnerEvent first = events.peek();
  97                 while (hasNext() && !condition.getAsBoolean())
  98                 {
  99                         events.remove();
 100                         lastTimeUpdated = first.getTiming();
 101                         first.run();
 102                         // Don't check after every run
 103                         checkStop = (checkStop + 1) % 10;
 104                         if (checkStop == 0 && System.currentTimeMillis() >= stopMillis)
 105                                 return ExecutionResult.EXEC_OUT_OF_TIME;
 106                         first = events.peek();
 107                 }
 108                 lastTimeUpdated = getSimulationTime();
 109                 return hasNext() ? ExecutionResult.EXEC_UNTIL_EMPTY : ExecutionResult.EXEC_UNTIL_CONDITION;
 110         }
 111
 112         /**
 113          * Sets the function, which defines the current simulation time at any time.
 114          *
 115          * @param time The return value of calling this function is the current simulation time.
 116          */
 117         public void setTimeFunction(LongSupplier time)
 118         {
 119                 this.time = time;
 120         }
 121
 122         /**
 123          * Calculates the current simulation time.
 124          *
 125          * @return The simulation time as defined by the time function.
 126          */
 127         public long getSimulationTime()
 128         {
 129                 return time.getAsLong();
 130         }
 131
 132         /**
 133          * Retrieves the timestamp of the next event.
 134          *
 135          * @return The timestamp of the next enqueued event, if the {@link Timeline} is not empty, -1 otherwise.
 136          */
 137         public long nextEventTime()
 138         {
 139                 if (!hasNext())
 140                         return -1;
 141                 return events.peek().getTiming();
 142         }
 143
 144         /**
 145          * Clears the {@link Timeline} of enqueued events.
 146          */
 147         public void reset()
 148         {
 149                 events.clear();
 150                 lastTimeUpdated = 0;
 151         }
 152
 153         /**
 154          * Adds a listener, that is called when a {@link TimelineEvent} is added.
 155          */
 156         public void addEventAddedListener(Consumer<TimelineEvent> listener)
 157         {
 158                 eventAddedListener.add(listener);
 159         }
 160
 161         /**
 162          * Removes the listener, if possible. It will no longer be called when a {@link TimelineEvent} is added.
 163          */
 164         public void removeEventAddedListener(Consumer<TimelineEvent> listener)
 165         {
 166                 eventAddedListener.remove(listener);
 167         }
 168
 169         /**
 170          * Adds an Event to the {@link Timeline}
 171          *
 172          * @param function       The {@link TimelineEventHandler} that will be executed, when the {@link InnerEvent} occurs on the timeline.
 173          * @param relativeTiming The amount of MI ticks in which the {@link InnerEvent} is called, starting from the current time.
 174          */
 175         public void addEvent(TimelineEventHandler function, int relativeTiming)
 176         {
 177                 long timing = getSimulationTime() + relativeTiming;
 178                 TimelineEvent event = new TimelineEvent(timing);
 179                 events.add(new InnerEvent(function, event));
 180                 eventAddedListener.forEach(l -> l.accept(event));
 181         }
 182
 183         private class InnerEvent implements Runnable, Comparable<InnerEvent>
 184         {
 185                 private final TimelineEventHandler function;
 186                 private final TimelineEvent event;
 187
 188                 /**
 189                  * Creates an {@link InnerEvent}
 190                  *
 191                  * @param function {@link TimelineEventHandler} to be executed when the {@link InnerEvent} occurs
 192                  * @param timing   Point in the MI simulation {@link Timeline}, at which the {@link InnerEvent} is executed;
 193                  */
 194                 InnerEvent(TimelineEventHandler function, TimelineEvent event)
 195                 {
 196                         this.function = function;
 197                         this.event = event;
 198                 }
 199
 200                 public long getTiming()
 201                 {
 202                         return event.getTiming();
 203                 }
 204
 205                 @Override
 206                 public void run()
 207                 {
 208                         function.handle(event);
 209                 }
 210
 211                 @Override
 212                 public String toString()
 213                 {
 214                         return event.toString();
 215                 }
 216
 217                 @Override
 218                 public int compareTo(InnerEvent o)
 219                 {
 220                         return timeCmp(getTiming(), o.getTiming());
 221                 }
 222         }
 223
 224         static int timeCmp(long a, long b)
 225         {
 226                 return Long.signum(a - b);
 227         }
 228
 229         @Override
 230         public String toString()
 231         {
 232                 return String.format("Simulation time: %s, Last update: %d, Events: %s", getSimulationTime(), lastTimeUpdated, events.toString());
 233         }
 234
 235         public enum ExecutionResult
 236         {
 237                 NOTHING_DONE, EXEC_UNTIL_EMPTY, EXEC_UNTIL_CONDITION, EXEC_OUT_OF_TIME
 238         }
 239 }