/// <summary>
/// Provides a method that allows you to provide a predicate
/// that will be invoked with any current value, and if your
/// predicate reutrns true, then the value is ALWAYS set to
/// your new value --- even when that is null, which REMOVES
/// this <paramref name="key"/>. Please note that this return
/// value is different from <see cref="Tag(TKey,TValue)"/>:
/// that method ALWAYS removes or replaces the current value,
/// and always returns a value that has been removed
/// (or replaced). This method ALWAYS returns the now
/// CURRENT value --- which MAY be null if your predicate
/// removes it, or makes no changes yet there is no current
/// value.
/// </summary>
/// <param name="key">Not null.</param>
/// <param name="predicate">Not null. Will be invoked with any
/// existing value, even if null. If this returns true, then
/// the predicate's returned new value is ALWAYS set, even if
/// null --- which REMOVES this key. If the predicate returns
/// false then the current value is not changhedl even if null.</param>
/// <returns>Always returns the now-current value;
/// which still may be null.</returns>
/// <exception cref="ArgumentNullException"></exception>
public TValue TryTag(TKey key, ValuePredicate <TValue> predicate)
{
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
TValue newValue;
lock (Tags) {
TValue currentValue = Tag(key);
if (!predicate(currentValue, out newValue))
{
return(currentValue);
}
if (newValue == null)
{
Tags.Remove(key);
}
else
{
Tags[key] = newValue;
}
}
RaiseTagsChanged();
return(newValue);
}
/// <summary>
/// Get number of values from end of the log
/// </summary>
/// <param name="size">How many to return</param>
/// <param name="msPerValue">How many milliseconds between values</param>
/// <param name="filter">Filter on Entry types</param>
/// <param name="getter">Delegate that projects a specific field of each entry</param>
/// <returns></returns>
public List <double> Tail(int size, int msPerValue, ValuePredicate filter, ValueGetter getter)
{
List <double> result = new List <double>();
long time = 0;
for (int i = this.History.Count - 1; i >= 0; i--)
{
Entry e = this.History[i];
if ((time == 0 || time - e.Timestamp > msPerValue) && filter(e))
{
result.Add(getter(e));
time = e.Timestamp;
if (result.Count >= size)
{
break;
}
}
}
result.Reverse();
return(result);
}
