[FLINK-10990][metrics] Enforce minimum timespan in MeterView

Pance · Nov 27, 2018 · 4cc9479 · 4cc9479
1 parent b379316
commit 4cc9479
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Showing 2 changed files with 16 additions and 1 deletion.
diff --git a/flink-metrics/flink-metrics-core/src/main/java/org/apache/flink/metrics/MeterView.java b/flink-metrics/flink-metrics-core/src/main/java/org/apache/flink/metrics/MeterView.java
@@ -50,7 +50,11 @@ public MeterView(int timeSpanInSeconds) {
 
  public MeterView(Counter counter, int timeSpanInSeconds) {
  this.counter = counter;
- this.timeSpanInSeconds = timeSpanInSeconds - (timeSpanInSeconds % UPDATE_INTERVAL_SECONDS);
+ // the time-span must be larger than the update-interval as otherwise the array has a size of 1,
+ // for which no rate can be computed as no distinct before/after measurement exists.
+ this.timeSpanInSeconds = Math.max(
+ timeSpanInSeconds - (timeSpanInSeconds % UPDATE_INTERVAL_SECONDS),
+ UPDATE_INTERVAL_SECONDS);
  this.values = new long[this.timeSpanInSeconds / UPDATE_INTERVAL_SECONDS + 1];
  }
 

diff --git a/flink-metrics/flink-metrics-core/src/test/java/org/apache/flink/metrics/MeterViewTest.java b/flink-metrics/flink-metrics-core/src/test/java/org/apache/flink/metrics/MeterViewTest.java
@@ -20,6 +20,7 @@
 
 import org.junit.Test;
 
+import static org.apache.flink.metrics.View.UPDATE_INTERVAL_SECONDS;
 import static org.junit.Assert.assertEquals;
 
 /**
@@ -94,4 +95,14 @@ public void testGetRate() {
  assertEquals(0.0, m.getRate(), 0.1); // 480 - 480 / 60
 
  }
+
+ @Test
+ public void testTimeSpanBelowUpdateRate() {
+ int timeSpanInSeconds = 1;
+ MeterView m = new MeterView(timeSpanInSeconds);
+ assert timeSpanInSeconds < UPDATE_INTERVAL_SECONDS;
+ m.markEvent();
+ m.update();
+ assertEquals(0.2, m.getRate(), 0.0);
+ }
 }