/// <summary>
/// Adds an old value with a fixed timestamp to the reservoir.
/// </summary>
/// <param name="value">the value to be added</param>
/// <param name="timestamp">the epoch timestamp of value in seconds</param>
public void Update(long value, long timestamp)
{
rescaleIfNeeded();
lockForRegularUsage();
_lock.EnterReadLock();
try
{
var itemWeight = Weight(timestamp - _startTime);
WeightedSample sample = new WeightedSample(value, itemWeight);
var random = ThreadLocalRandom.NextNonzeroDouble();
var priority = itemWeight / random;
var newCount = _count.IncrementAndGet();
if (newCount <= _size)
{
_values.AddOrUpdate(priority, sample, (p, v) => v);
}
else
{
var first = _values.Keys.Min();
if (first < priority)
{
_values.AddOrUpdate(priority, sample, (p, v) => v);
WeightedSample removed;
while (!_values.TryRemove(first, out removed))
{
first = _values.Keys.First();
}
}
}
}
finally
{
unlockForRegularUsage();
_lock.ExitReadLock();
}
}
/// <summary>
/// Adds a recorded value
/// </summary>
/// <param name="value">the length of the value</param>
public void Update(long value)
{
count.IncrementAndGet();
reservoir.Update(value);
}