HDDS-1811. Prometheus metrics are broken.

Signed-off-by: Anu Engineer <aengineer@apache.org>

hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/transport/server/ratis/CSMMetrics.java

@@ -62,7 +62,7 @@ public class CSMMetrics {
   public CSMMetrics() {
     int numCmdTypes = ContainerProtos.Type.values().length;
     this.opsLatency = new MutableRate[numCmdTypes];
-    this.registry = new MetricsRegistry(CSMMetrics.class.getName());
+    this.registry = new MetricsRegistry(CSMMetrics.class.getSimpleName());
     for (int i = 0; i < numCmdTypes; i++) {
       opsLatency[i] = registry.newRate(
           ContainerProtos.Type.forNumber(i + 1).toString(),

hadoop-hdds/framework/src/main/java/org/apache/hadoop/hdds/server/PrometheusMetricsSink.java

@@ -23,7 +23,6 @@
 import java.io.Writer;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import org.apache.commons.lang3.StringUtils;
@@ -47,8 +46,8 @@ public class PrometheusMetricsSink implements MetricsSink {
    */
   private Map<String, String> metricLines = new HashMap<>();
 
-  private static final Pattern UPPER_CASE_SEQ =
+  private static final Pattern SPLIT_PATTERN =
-      Pattern.compile("([A-Z]*)([A-Z])");
+      Pattern.compile("(?<!(^|[A-Z_]))(?=[A-Z])|(?<!^)(?=[A-Z][a-z])");
 
   public PrometheusMetricsSink() {
   }
@@ -88,7 +87,7 @@ public void putMetrics(MetricsRecord metricsRecord) {
   }
 
   /**
-   * Convert CamelCase based namess to lower-case names where the separator
+   * Convert CamelCase based names to lower-case names where the separator
    * is the underscore, to follow prometheus naming conventions.
    */
   public String prometheusName(String recordName,
@@ -99,29 +98,12 @@ public String prometheusName(String recordName,
         recordName.startsWith(ROCKSDB_CONTEXT_PREFIX)) {
       return recordName.toLowerCase() + "_" + metricName.toLowerCase();
     }
-    String baseName = upperFirst(recordName) + upperFirst(metricName);
-    Matcher m = UPPER_CASE_SEQ.matcher(baseName);
-    StringBuffer sb = new StringBuffer();
-    while (m.find()) {
-      String replacement = "_" + m.group(2).toLowerCase();
-      if (m.group(1).length() > 0) {
-        replacement = "_" + m.group(1).toLowerCase() + replacement;
-      }
-      m.appendReplacement(sb, replacement);
-    }
-    m.appendTail(sb);
-
-    //always prefixed with "_"
-    return sb.toString().substring(1);
-  }
-
-  private String upperFirst(String name) {
-    if (Character.isLowerCase(name.charAt(0))) {
-      return Character.toUpperCase(name.charAt(0)) + name.substring(1);
-    } else {
-      return name;
-    }
 
+    String baseName = StringUtils.capitalize(recordName)
+        + StringUtils.capitalize(metricName);
+    baseName = baseName.replace('-', '_');
+    String[] parts = SPLIT_PATTERN.split(baseName);
+    return String.join("_", parts).toLowerCase();
   }
 
   @Override

hadoop-hdds/framework/src/test/java/org/apache/hadoop/hdds/server/TestPrometheusMetricsSink.java

@@ -30,7 +30,7 @@
 import org.junit.Assert;
 import org.junit.Test;
 
-import static org.apache.commons.codec.CharEncoding.UTF_8;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
 /**
  * Test prometheus Sink.
@@ -59,10 +59,11 @@ public void testPublish() throws IOException {
     writer.flush();
 
     //THEN
-    System.out.println(stream.toString(UTF_8));
+    String writtenMetrics = stream.toString(UTF_8.name());
+    System.out.println(writtenMetrics);
     Assert.assertTrue(
         "The expected metric line is missing from prometheus metrics output",
-        stream.toString(UTF_8).contains(
+        writtenMetrics.contains(
             "test_metrics_num_bucket_create_fails{context=\"dfs\"")
     );
 
@@ -71,7 +72,7 @@ public void testPublish() throws IOException {
   }
 
   @Test
-  public void testNaming() throws IOException {
+  public void testNamingCamelCase() {
     PrometheusMetricsSink sink = new PrometheusMetricsSink();
 
     Assert.assertEquals("rpc_time_some_metrics",
@@ -82,18 +83,35 @@ public void testNaming() throws IOException {
 
     Assert.assertEquals("rpc_time_small",
         sink.prometheusName("RpcTime", "small"));
+  }
 
+  @Test
+  public void testNamingRocksDB() {
     //RocksDB metrics are handled differently.
-
+    PrometheusMetricsSink sink = new PrometheusMetricsSink();
     Assert.assertEquals("rocksdb_om.db_num_open_connections",
         sink.prometheusName("Rocksdb_om.db", "num_open_connections"));
   }
 
+  @Test
+  public void testNamingPipeline() {
+    PrometheusMetricsSink sink = new PrometheusMetricsSink();
+
+    String recordName = "SCMPipelineMetrics";
+    String metricName = "NumBlocksAllocated-"
+        + "RATIS-THREE-47659e3d-40c9-43b3-9792-4982fc279aba";
+    Assert.assertEquals(
+        "scm_pipeline_metrics_"
+            + "num_blocks_allocated_"
+            + "ratis_three_47659e3d_40c9_43b3_9792_4982fc279aba",
+        sink.prometheusName(recordName, metricName));
+  }
+
   /**
    * Example metric pojo.
    */
   @Metrics(about = "Test Metrics", context = "dfs")
-  public static class TestMetrics {
+  private static class TestMetrics {
 
     @Metric
     private MutableCounterLong numBucketCreateFails;