multiple changes

 * added scan problems column that sums scan errors, scan mem pauses, and scan mem returns
 * added scan open files column and scan yield column
 * fixed bug with computing cache hit ratio
 * narrowed what stats are used to display specific metric types
 * cleaned up some errors in the Metric enum

Author: keith-turner

core/src/main/java/org/apache/accumulo/core/metrics/Metric.java

@@ -83,10 +83,10 @@ public enum Metric {
       MetricDocSection.COMPACTION, "Majc In Progress", null, NUMBER),
   COMPACTOR_MAJC_STUCK("accumulo.compaction.majc.stuck", MetricType.LONG_TASK_TIMER,
       "Number and duration of stuck major compactions.", MetricDocSection.COMPACTION, "Majc Stuck",
-      null, NUMBER),
+      null, DURATION),
   COMPACTOR_MINC_STUCK("accumulo.compaction.minc.stuck", MetricType.LONG_TASK_TIMER,
       "Number and duration of stuck minor compactions.", MetricDocSection.COMPACTION, "Minc Stuck",
-      null, NUMBER),
+      null, DURATION),
   COMPACTOR_ENTRIES_READ("accumulo.compaction.entries.read", MetricType.FUNCTION_COUNTER,
       "Number of entries read by all compactions that have run on this compactor (majc) or tserver (minc).",
       MetricDocSection.COMPACTION, "Compaction Entries Read", null, NUMBER),
@@ -122,7 +122,7 @@ public enum Metric {
       MetricDocSection.COMPACTION, "Compaction Queue Avg Job Age", null, NUMBER),
   COMPACTOR_JOB_PRIORITY_QUEUE_JOBS_POLL_TIMER("accumulo.compaction.queue.jobs.exit.time",
       MetricType.TIMER, "Tracks time a job spent in the queue before exiting the queue.",
-      MetricDocSection.COMPACTION, "Compaction Queue Job Time Queued", null, NUMBER),
+      MetricDocSection.COMPACTION, "Compaction Queue Job Time Queued", null, DURATION),
 
   // Fate Metrics
   FATE_TYPE_IN_PROGRESS("accumulo.fate.ops.in.progress.by.type", MetricType.GAUGE,
@@ -242,11 +242,11 @@ public enum Metric {
   // Scan Server Metrics
   SCAN_RESERVATION_TOTAL_TIMER("accumulo.scan.reservation.total.timer", MetricType.TIMER,
       "Average time to reserve a tablet's files for scan.", MetricDocSection.SCAN_SERVER,
-      "Mean Reservation", null, NUMBER),
+      "Mean Reservation", null, DURATION),
   SCAN_RESERVATION_WRITEOUT_TIMER("accumulo.scan.reservation.writeout.timer", MetricType.TIMER,
       "Time to write out a tablets file reservations for scan.", MetricDocSection.SCAN_SERVER,
-      "Scan Reservation Write Time", null, NUMBER),
-  SCAN_RESERVATION_FILES("accumulo.scan.reservation.files", MetricType.TIMER,
+      "Scan Reservation Write Time", null, DURATION),
+  SCAN_RESERVATION_FILES("accumulo.scan.reservation.files", MetricType.GAUGE,
       "The number of files reserved by a scan server.", MetricDocSection.SCAN_SERVER,
       "Files Reserved", null, NUMBER),
   SCAN_RESERVATION_CONFLICT_COUNTER("accumulo.scan.reservation.conflict.count", MetricType.COUNTER,
@@ -261,7 +261,7 @@ public enum Metric {
 
   // Scan Metrics
   SCAN_TIMES("accumulo.scan.times", MetricType.TIMER, "Scan session lifetime (creation to close).",
-      MetricDocSection.SCAN, "Scan Session Total Time", null, NUMBER),
+      MetricDocSection.SCAN, "Scan Session Total Time", null, DURATION),
   SCAN_OPEN_FILES("accumulo.scan.files.open", MetricType.GAUGE, "Number of files open for scans.",
       MetricDocSection.SCAN, "Scan Files Open", null, NUMBER),
   SCAN_RESULTS("accumulo.scan.result", MetricType.DISTRIBUTION_SUMMARY, "Results per scan.",
@@ -310,10 +310,11 @@ public enum Metric {
   // Minor Compaction Metrics
   MINC_QUEUED("accumulo.compaction.minc.queued", MetricType.TIMER,
       "Queued minor compactions time queued.", MetricDocSection.COMPACTION, "Minc Queued", null,
-      NUMBER),
+      DURATION),
   MINC_RUNNING("accumulo.compaction.minc.running", MetricType.TIMER,
-      "Minor compactions time active.", MetricDocSection.COMPACTION, "Minc Running", null, NUMBER),
-  MINC_PAUSED("accumulo.compaction.minc.paused", MetricType.COUNTER,
+      "Minor compactions time active.", MetricDocSection.COMPACTION, "Minc Running", null,
+      DURATION),
+  MINC_PAUSED("accumulo.compaction.minc.paused", MetricType.FUNCTION_COUNTER,
       "Number of paused minor compactions.", MetricDocSection.COMPACTION, "Minc Paused", null,
       NUMBER),
 
@@ -323,19 +324,19 @@ public enum Metric {
       MetricDocSection.TABLET_SERVER, "Ingest Errors", null, NUMBER),
   UPDATE_LOCK("accumulo.updates.lock", MetricType.TIMER,
       "Average time taken for conditional mutation to get a row lock.",
-      MetricDocSection.TABLET_SERVER, "Conditional Mutation Row Lock Wait Time", null, NUMBER),
+      MetricDocSection.TABLET_SERVER, "Conditional Mutation Row Lock Wait Time", null, DURATION),
   UPDATE_CHECK("accumulo.updates.check", MetricType.TIMER,
       "Average time taken for conditional mutation to check conditions.",
-      MetricDocSection.TABLET_SERVER, "Conditional Mutation Condition Check Time", null, NUMBER),
+      MetricDocSection.TABLET_SERVER, "Conditional Mutation Condition Check Time", null, DURATION),
   UPDATE_COMMIT("accumulo.updates.commit", MetricType.TIMER,
       "Average time taken to commit a mutation.", MetricDocSection.TABLET_SERVER,
-      "Mutation Commit Avg Total Time", null, NUMBER),
+      "Mutation Commit Avg Total Time", null, DURATION),
   UPDATE_COMMIT_PREP("accumulo.updates.commit.prep", MetricType.TIMER,
       "Average time taken to prepare to commit a single mutation.", MetricDocSection.TABLET_SERVER,
-      "Mutation Commit Avg Prep Time", null, NUMBER),
+      "Mutation Commit Avg Prep Time", null, DURATION),
   UPDATE_WALOG_WRITE("accumulo.updates.walog.write", MetricType.TIMER,
       "Time taken to write a batch of mutations to WAL.", MetricDocSection.TABLET_SERVER,
-      "WAL Write Time", null, NUMBER),
+      "WAL Write Time", null, DURATION),
   UPDATE_MUTATION_ARRAY_SIZE("accumulo.updates.mutation.arrays.size",
       MetricType.DISTRIBUTION_SUMMARY, "Batch size of mutations from client.",
       MetricDocSection.TABLET_SERVER, "Mutation Batch Size", null, NUMBER),

server/monitor/src/main/java/org/apache/accumulo/monitor/next/views/CacheSizeColumnFactory.java

@@ -21,14 +21,15 @@
 import java.util.List;
 import java.util.Map;
 
-import com.google.common.base.Preconditions;
 import org.apache.accumulo.core.client.admin.servers.ServerId;
 import org.apache.accumulo.core.metrics.Metric;
 import org.apache.accumulo.core.metrics.flatbuffers.FMetric;
 import org.apache.accumulo.core.metrics.flatbuffers.FTag;
 import org.apache.accumulo.core.process.thrift.MetricResponse;
 import org.apache.accumulo.monitor.next.SystemInformation;
 
+import com.google.common.base.Preconditions;
+
 public class CacheSizeColumnFactory implements ColumnFactory {
 
   private final String cacheName;

server/monitor/src/main/java/org/apache/accumulo/monitor/next/views/MetricColumnFactory.java

@@ -21,6 +21,7 @@
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import org.apache.accumulo.core.client.admin.servers.ServerId;
@@ -34,6 +35,7 @@ public class MetricColumnFactory implements ColumnFactory {
 
   private final Column column;
   private final boolean computeRate;
+  private final Predicate<String> statPredicate;
 
   MetricColumnFactory(Metric metric) {
     String classes;
@@ -51,6 +53,14 @@ public class MetricColumnFactory implements ColumnFactory {
     }
     this.column = new Column(metric.getName(), metric.getColumnHeader(),
         metric.getColumnDescription(), classes);
+
+    statPredicate = switch (metric.getType()) {
+      case GAUGE -> sv -> sv.equals(StatType.VALUE);
+      case COUNTER, FUNCTION_COUNTER -> sv -> sv.equals(StatType.COUNT);
+      case TIMER, DISTRIBUTION_SUMMARY -> sv -> sv.equals(StatType.AVERAGE);
+      case LONG_TASK_TIMER -> sv -> sv.equals(StatType.MAX);
+      case CACHE -> StatType.COUNT_OR_VALUE; // TODO this class does not really support this type
+    };
   }
 
   @Override
@@ -61,7 +71,7 @@ public Column getColumn() {
   @Override
   public Object getRowData(ServerId sid, MetricResponse mr,
       Map<String,List<FMetric>> serverMetrics) {
-    var sum = sum(serverMetrics.getOrDefault(column.key(), List.of()), StatType.COUNT_OR_VALUE);
+    var sum = sum(serverMetrics.getOrDefault(column.key(), List.of()), statPredicate);
     if (computeRate) {
       return computeRate(sum);
     } else {

server/monitor/src/main/java/org/apache/accumulo/monitor/next/views/MultiSumColumnFactory.java

@@ -0,0 +1,87 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.accumulo.monitor.next.views;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import org.apache.accumulo.core.client.admin.servers.ServerId;
+import org.apache.accumulo.core.metrics.Metric;
+import org.apache.accumulo.core.metrics.flatbuffers.FMetric;
+import org.apache.accumulo.core.process.thrift.MetricResponse;
+
+import com.google.common.base.Preconditions;
+import com.google.common.hash.Hashing;
+
+/**
+ * Sums multiple metrics of the same type for a column value
+ */
+public class MultiSumColumnFactory implements ColumnFactory {
+
+  private final List<MetricColumnFactory> colFactories;
+  private final TableData.Column column;
+
+  MultiSumColumnFactory(String label, Metric... metrics) {
+    Preconditions.checkArgument(metrics.length > 1);
+    // ensure all metrics are of the same type
+    Preconditions
+        .checkArgument(Arrays.stream(metrics).allMatch(m -> m.getType() == metrics[0].getType()));
+    // ensure all metrics have the same display type
+    Preconditions.checkArgument(
+        Arrays.stream(metrics).allMatch(m -> Set.of(Arrays.asList(m.getColumnClasses()))
+            .equals(Set.of(Arrays.asList(metrics[0].getColumnClasses())))));
+
+    this.colFactories = Arrays.stream(metrics).map(MetricColumnFactory::new).toList();
+
+    StringBuilder description = new StringBuilder("A sum of the following metrics :");
+    var hasher = Hashing.sha256().newHasher();
+    for (int i = 0; i < metrics.length; i++) {
+      description.append(" ");
+      description.append((i + 1) + ") " + metrics[i].getDescription());
+      if (!metrics[i].getDescription().endsWith(".")) {
+        description.append(".");
+      }
+      hasher.putString(metrics[i].getName(), UTF_8);
+    }
+
+    var key = hasher.hash().toString();
+
+    this.column = new TableData.Column(key, label, description.toString(),
+        colFactories.get(0).getColumn().uiClass());
+  }
+
+  @Override
+  public TableData.Column getColumn() {
+    return column;
+  }
+
+  @Override
+  public Object getRowData(ServerId sid, MetricResponse mr,
+      Map<String,List<FMetric>> serverMetrics) {
+    Number sum = null;
+    for (var colf : colFactories) {
+      sum = add(sum, (Number) colf.getRowData(sid, mr, serverMetrics));
+    }
+    return sum;
+  }
+}

server/monitor/src/main/java/org/apache/accumulo/monitor/next/views/RatioColumnFactory.java

@@ -57,7 +57,7 @@ public Object getRowData(ServerId sid, MetricResponse mr,
     }
 
     var numeratorSum = sum(n, StatType.COUNT_OR_VALUE).doubleValue();
-    var denominatorSum = sum(n, StatType.COUNT_OR_VALUE).doubleValue();
+    var denominatorSum = sum(d, StatType.COUNT_OR_VALUE).doubleValue();
 
     if (denominatorSum == 0) {
       return null;

server/monitor/src/main/java/org/apache/accumulo/monitor/next/views/TableDataFactory.java

@@ -83,6 +83,7 @@ public static class StatType {
     public static final String COUNT = "count";
     public static final String VALUE = "value";
     public static final String AVERAGE = "avg";
+    public static final String MAX = "max";
 
     public static final Predicate<String> COUNT_OR_VALUE = s -> COUNT.equals(s) || VALUE.equals(s);
   }
@@ -251,7 +252,8 @@ private static void scanColumns(List<ColumnFactory> cols) {
     cols.add(new ExecutorColumnFactory(ExecutorColumnFactory.Type.QUEUED,
         ThreadPoolNames.SCAN_EXECUTOR_PREFIX.poolName, "Queued scans",
         "Scan task queued on all scan thread pools"));
-    cols.add(new MetricColumnFactory(Metric.SCAN_ERRORS));
+    cols.add(new MultiSumColumnFactory("Scan Problems", Metric.SCAN_ERRORS,
+        Metric.SCAN_PAUSED_FOR_MEM, Metric.SCAN_RETURN_FOR_MEM));
     cols.add(new MetricColumnFactory(Metric.SCAN_SCANNED_ENTRIES));
     cols.add(new MetricColumnFactory(Metric.SCAN_QUERY_SCAN_RESULTS));
     cols.add(new MetricColumnFactory(Metric.SCAN_QUERY_SCAN_RESULTS_BYTES));
@@ -261,6 +263,8 @@ private static void scanColumns(List<ColumnFactory> cols) {
     cols.add(new RatioColumnFactory("Data cache hit",
         "Ratio of hits/total request for the data block cache", Metric.BLOCKCACHE_DATA_HITCOUNT,
         Metric.BLOCKCACHE_DATA_REQUESTCOUNT));
+    cols.add(new MetricColumnFactory(Metric.SCAN_OPEN_FILES));
+    cols.add(new MetricColumnFactory(Metric.SCAN_YIELDS));
   }
 
   private static void scanServerColumns(List<ColumnFactory> cols) {