Add TimeWindow

zhulik · Feb 10, 2023 · 5ea0b68 · 5ea0b68
1 parent 160a2ea
commit 5ea0b68
Showing 1 changed file with 43 additions and 0 deletions.
diff --git a/lib/nats_streamer/metrics/time_window.rb b/lib/nats_streamer/metrics/time_window.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class NatsStreamer::Metrics::TimeWindow
+  include NatsStreamer::Helpers
+
+  option :duration, type: T::Integer # milliseconds
+
+  def push(value)
+    purge_old!
+    history << [timestamp, value]
+  end
+
+  def stats
+    purge_old!
+    values = history.map { _1[1] }
+
+    avg = values.count.positive? ? values.sum.to_f / values.count : nil
+
+    min, max = values.minmax
+    {
+      min:,
+      max:,
+      avg:,
+      count:
+    }
+  end
+
+  def count = history.count
+
+  private
+
+  memoize def history = []
+
+  def timestamp = (Time.now.to_f * 1000).to_i
+
+  def purge_old!
+    now = timestamp
+
+    index = history.bsearch_index { _1.first > (now - duration) }
+    history.clear if index.nil?
+    history.shift(index) if index
+  end
+end