Implement TDigestHistogram#toString

trinodb · Nov 25, 2021 · 9a824be · 9a824be
1 parent ef5084c
commit 9a824be
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diff --git a/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java b/lib/trino-plugin-toolkit/src/main/java/io/trino/plugin/base/metrics/TDigestHistogram.java
@@ -25,7 +25,10 @@
 
 import java.util.Base64;
 
+import static com.google.common.base.MoreObjects.ToStringHelper;
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static io.airlift.slice.Slices.wrappedBuffer;
+import static java.lang.String.format;
 
 public class TDigestHistogram
         implements Distribution<TDigestHistogram>
@@ -66,6 +69,16 @@ public double getPercentile(double percentile)
         return digest.valueAt(percentile / 100.0);
     }
 
+    @Override
+    public String toString()
+    {
+        ToStringHelper helper = toStringHelper(this).add("count", digest.getCount());
+        for (int q = 0; q <= 100; q += 10) {
+            helper.add(format("p%d", q), getPercentile(q));
+        }
+        return helper.toString();
+    }
+
     public static class TDigestToBase64Converter
             extends StdConverter<TDigest, String>
     {

diff --git a/lib/trino-plugin-toolkit/src/test/java/io/trino/plugin/base/metrics/TestMetrics.java b/lib/trino-plugin-toolkit/src/test/java/io/trino/plugin/base/metrics/TestMetrics.java
@@ -61,6 +61,7 @@ public void testMergeHistogram()
         assertThat(merged.getTotal()).isEqualTo(3L);
         assertThat(merged.getPercentile(0)).isEqualTo(5.0);
         assertThat(merged.getPercentile(100)).isEqualTo(10.0);
+        assertThat(merged.toString()).matches("TDigestHistogram\\{count=3.0, p0=5\\.0, p10=5\\.0, .*, p90=10\\.0, p100=10\\.0\\}");
     }
 
     @Test