Add support for collecting metrics on a node

This commit adds all the necessary bits to expose REST endpoints to retrieve tpstats, dropped messages and client requests metrics for a specific node.

src/server/src/main/java/io/cassandrareaper/AppContext.java

@@ -15,6 +15,7 @@
 package io.cassandrareaper;
 
 import io.cassandrareaper.jmx.JmxConnectionFactory;
+import io.cassandrareaper.service.MetricsGrabber;
 import io.cassandrareaper.service.PurgeManager;
 import io.cassandrareaper.service.RepairManager;
 import io.cassandrareaper.service.SnapshotManager;
@@ -48,6 +49,7 @@ public final class AppContext {
   public MetricRegistry metricRegistry = new MetricRegistry();
   public SnapshotManager snapshotManager;
   public PurgeManager purgeManager;
+  public MetricsGrabber metricsGrabber;
 
   private static String initialiseInstanceAddress() {
     String reaperInstanceAddress;

src/server/src/main/java/io/cassandrareaper/ReaperApplication.java

@@ -19,6 +19,7 @@
 import io.cassandrareaper.jmx.JmxConnectionFactory;
 import io.cassandrareaper.jmx.JmxConnectionsInitializer;
 import io.cassandrareaper.resources.ClusterResource;
+import io.cassandrareaper.resources.NodeStatsResource;
 import io.cassandrareaper.resources.PingResource;
 import io.cassandrareaper.resources.ReaperHealthCheck;
 import io.cassandrareaper.resources.RepairRunResource;
@@ -27,6 +28,7 @@
 import io.cassandrareaper.resources.auth.LoginResource;
 import io.cassandrareaper.resources.auth.ShiroExceptionMapper;
 import io.cassandrareaper.service.AutoSchedulingManager;
+import io.cassandrareaper.service.MetricsGrabber;
 import io.cassandrareaper.service.PurgeManager;
 import io.cassandrareaper.service.RepairManager;
 import io.cassandrareaper.service.SchedulingManager;
@@ -158,6 +160,9 @@ public void run(ReaperApplicationConfiguration config, Environment environment)
         context,
         environment.lifecycle().executorService("SnapshotManager").minThreads(5).maxThreads(5).build());
 
+    context.snapshotManager = SnapshotManager.create(context);
+    context.metricsGrabber = MetricsGrabber.create(context);
+
     int repairThreads = config.getRepairRunThreadCount();
     LOG.info("initializing runner thread pool with {} threads", repairThreads);
 
@@ -235,6 +240,9 @@ public void run(ReaperApplicationConfiguration config, Environment environment)
     final SnapshotResource snapshotResource = new SnapshotResource(context);
     environment.jersey().register(snapshotResource);
 
+    final NodeStatsResource nodeStatsResource = new NodeStatsResource(context);
+    environment.jersey().register(nodeStatsResource);
+
     if (config.isAccessControlEnabled()) {
       SessionHandler sessionHandler = new SessionHandler();
       sessionHandler.setMaxInactiveInterval((int) config.getAccessControl().getSessionTimeout().getSeconds());

src/server/src/main/java/io/cassandrareaper/core/DroppedMessages.java

@@ -0,0 +1,112 @@
+/*
+ * Licensed 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
+ *
+ *     http://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 io.cassandrareaper.core;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonPOJOBuilder;
+
+@JsonDeserialize(builder = DroppedMessages.Builder.class)
+public final class DroppedMessages {
+  private final String name;
+  private final Integer count;
+  private final Double oneMinuteRate;
+  private final Double fiveMinuteRate;
+  private final Double fifteenMinuteRate;
+  private final Double meanRate;
+
+  private DroppedMessages(Builder builder) {
+    this.name = builder.name;
+    this.count = builder.count;
+    this.oneMinuteRate = builder.oneMinuteRate;
+    this.fiveMinuteRate = builder.fiveMinuteRate;
+    this.fifteenMinuteRate = builder.fifteenMinuteRate;
+    this.meanRate = builder.meanRate;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public Integer getCount() {
+    return count;
+  }
+
+  public Double getOneMinuteRate() {
+    return oneMinuteRate;
+  }
+
+  public Double getFiveMinuteRate() {
+    return fiveMinuteRate;
+  }
+
+  public Double getFifteenMinuteRate() {
+    return fifteenMinuteRate;
+  }
+
+  public Double getMeanRate() {
+    return meanRate;
+  }
+
+
+  public static Builder builder() {
+    return new Builder();
+  }
+
+  @JsonPOJOBuilder(buildMethodName = "build", withPrefix = "with")
+  public static final class Builder {
+    private String name;
+    private Integer count;
+    private Double oneMinuteRate;
+    private Double fiveMinuteRate;
+    private Double fifteenMinuteRate;
+    private Double meanRate;
+
+    private Builder() {}
+
+    public Builder withName(String name) {
+      this.name = name;
+      return this;
+    }
+
+    public Builder withCount(Integer count) {
+      this.count = count;
+      return this;
+    }
+
+    public Builder withOneMinuteRate(Double oneMinuteRate) {
+      this.oneMinuteRate = oneMinuteRate;
+      return this;
+    }
+
+    public Builder withFiveMinuteRate(Double fiveMinuteRate) {
+      this.fiveMinuteRate = fiveMinuteRate;
+      return this;
+    }
+
+    public Builder withFifteenMinuteRate(Double fifteenMinuteRate) {
+      this.fifteenMinuteRate = fifteenMinuteRate;
+      return this;
+    }
+
+    public Builder withMeanRate(Double meanRate) {
+      this.meanRate = meanRate;
+      return this;
+    }
+
+    public DroppedMessages build() {
+      return new DroppedMessages(this);
+    }
+  }
+}

src/server/src/main/java/io/cassandrareaper/core/JmxStat.java

@@ -0,0 +1,93 @@
+/*
+ * Licensed 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
+ *
+ *     http://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 io.cassandrareaper.core;
+
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import com.fasterxml.jackson.databind.annotation.JsonPOJOBuilder;
+
+@JsonDeserialize(builder = JmxStat.Builder.class)
+public final class JmxStat {
+  private final String scope;
+  private final String name;
+  private final String attribute;
+  private final Double value;
+
+  private JmxStat(Builder builder) {
+    this.scope = builder.scope;
+    this.name = builder.name;
+    this.attribute = builder.attribute;
+    this.value = builder.value;
+  }
+
+  public String getScope() {
+    return scope;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public String getAttribute() {
+    return attribute;
+  }
+
+  public Double getValue() {
+    return value;
+  }
+
+
+  @Override
+  public String toString() {
+    return scope + "/" + name + "/" + attribute + " = " + value;
+  }
+
+  public static Builder builder() {
+    return new Builder();
+  }
+
+  @JsonPOJOBuilder(buildMethodName = "build", withPrefix = "with")
+  public static final class Builder {
+    private String scope;
+    private String name;
+    private String attribute;
+    private Double value;
+
+    private Builder() {}
+
+    public Builder withScope(String scope) {
+      this.scope = scope;
+      return this;
+    }
+
+    public Builder withName(String name) {
+      this.name = name;
+      return this;
+    }
+
+    public Builder withAttribute(String attribute) {
+      this.attribute = attribute;
+      return this;
+    }
+
+    public Builder withValue(Double value) {
+      this.value = value;
+      return this;
+    }
+
+    public JmxStat build() {
+      return new JmxStat(this);
+    }
+  }
+}