public SimpleScaleStrategy(string databaseId, string collectionId)
{
// TODO make configurable
var options = new SimpleScaleStrategyOptions()
{
TrendDuration = TimeSpan.FromSeconds(30),
TrendInterval = TimeSpan.FromSeconds(1),
};
RegisterObserver(databaseId, collectionId, options);
}
private void RegisterObserver(string databaseId, string collectionId, SimpleScaleStrategyOptions options)
{
// Note: this is an overly simplistic approach
// CosmosDb RU is calculated/charged per second
_requestChargeSubject.Buffer(TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(1))
.Select(x => x.Sum())
.Buffer(options.TrendDuration, options.TrendInterval)
.Select(graphItem =>
{
var lineIntercept = Fit.Line(Enumerable.Range(0, graphItem.Count).Select(m => (double)m).ToArray(), graphItem.ToArray());
return(new TrendModel()
{
Intercept = lineIntercept.Item1,
Slope = lineIntercept.Item2,
LastRecordIndex = graphItem.Count
});
})
.Select(trend => Observable.FromAsync(async cancelToken => await ScaleUnstableTrendAsync(databaseId, collectionId, trend)))
.Subscribe();
}