Android Open Source - interdroid-swan Abstract Memory Sensor

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License

The source code is released under:

Copyright (c) 2008-2011 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...

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Java Source Code

package interdroid.swan.sensors;
//from  w  w w  .jav a2  s.co m
import interdroid.swan.swansong.TimestampedValue;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Abstract class that implements basic functionality for sensors. Descendants
 * only have to implement requestReading() and onEntityServiceLevelChange(). The
 * rest can be overridden optionally.
 */
public abstract class AbstractMemorySensor extends AbstractSensorBase {

  /**
   * The map of values for this sensor.
   */
  private final Map<String, List<TimestampedValue>> values = new HashMap<String, List<TimestampedValue>>();
  
  private long mReadings = 0;
  private long mLastReadingTimestamp = 0;

  /**
   * @return the values
   */
  public final Map<String, List<TimestampedValue>> getValues() {
    return values;
  }

  @Override
  public final void init() {
    for (String valuePath : VALUE_PATHS) {
      expressionIdsPerValuePath.put(valuePath, new ArrayList<String>());
      getValues()
          .put(valuePath,
              Collections
                  .synchronizedList(new ArrayList<TimestampedValue>()));
    }
  }

  /**
   * Trims the values to the given length.
   * 
   * @param history
   *            the number of items to keep
   */
  private final void trimValues(final int history) {
    for (String path : VALUE_PATHS) {
      if (getValues().get(path).size() >= history) {
        getValues().get(path).remove(getValues().get(path).size() - 1);
      }
    }
  }

  /**
   * Adds a value for the given value path to the history.
   * 
   * @param valuePath
   *            the value path
   * @param now
   *            the current time
   * @param value
   *            the value
   * @param historySize
   *            the history size
   */
  protected final void putValueTrimSize(final String valuePath,
      final String id, final long now, final Object value,
      final int historySize) {
    updateReadings(now);
    getValues().get(valuePath).add(0, new TimestampedValue(value, now));
    trimValues(historySize);
    if (id != null) {
      notifyDataChangedForId(id);
    } else {
      notifyDataChanged(valuePath);
    }
  }

  /**
   * Adds a value for the given value path to the history.
   * 
   * @param valuePath
   *            the value path
   * @param now
   *            the current time
   * @param value
   *            the value
   * @param historyLength
   *            the history length
   */
  protected final void putValueTrimTime(final String valuePath,
      final String id, final long now, final Object value,
      final long historyLength) {
    updateReadings(now);
    getValues().get(valuePath).add(0, new TimestampedValue(value, now));
    trimValueByTime(now - historyLength);
    if (id != null) {
      notifyDataChangedForId(id);
    } else {
      notifyDataChanged(valuePath);
    }
  }
  
  private void updateReadings(long now) {
    if (now != mLastReadingTimestamp) {
      mReadings++;
      mLastReadingTimestamp = now;
    }
  }

  /**
   * Trims values past the given expire time.
   * 
   * @param expire
   *            the time to trim after
   */
  private final void trimValueByTime(final long expire) {
    for (String valuePath : VALUE_PATHS) {
      List<TimestampedValue> values = getValues().get(valuePath);
      while ((values.size() > 0 && values.get(values.size() - 1)
          .getTimestamp() < expire)) {
        values.remove(values.size() - 1);
      }
    }
  }

  @Override
  public final List<TimestampedValue> getValues(final String id,
      final long now, final long timespan) {
    return getValuesForTimeSpan(values.get(registeredValuePaths.get(id)),
        now, timespan);
  }
  
  @Override
  public long getReadings() {
    return mReadings;
  }
}

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