TaggedMetricRegistry composability

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/DefaultTaggedMetricRegistry.java

@@ -24,7 +24,7 @@
 import com.codahale.metrics.Metric;
 import com.codahale.metrics.Timer;
 import com.google.auto.service.AutoService;
-import java.util.Collections;
+import com.google.common.collect.ImmutableMap;
 import java.util.Map;
 import java.util.Optional;
 import java.util.concurrent.ConcurrentHashMap;
@@ -36,6 +36,7 @@ public final class DefaultTaggedMetricRegistry implements TaggedMetricRegistry {
     private static final TaggedMetricRegistry DEFAULT = new DefaultTaggedMetricRegistry();
 
     private final Map<MetricName, Metric> registry = new ConcurrentHashMap<>();
+    private final Map<Map<String, String>, TaggedMetricSet> taggedRegistries = new ConcurrentHashMap<>();
 
     public DefaultTaggedMetricRegistry() {}
 
@@ -93,14 +94,34 @@ public Timer timer(MetricName metricName, Supplier<Timer> timerSupplier) {
 
     @Override
     public Map<MetricName, Metric> getMetrics() {
-        return Collections.unmodifiableMap(registry);
+        ImmutableMap.Builder<MetricName, Metric> result = ImmutableMap.<MetricName, Metric>builder()
+                .putAll(registry);
+        taggedRegistries.forEach((tags, metrics) -> metrics.getMetrics()
+                .forEach((metricName, metric) -> result.put(
+                        MetricName.builder()
+                                .from(metricName)
+                                .putAllSafeTags(tags)
+                                .build(),
+                        metric)));
+
+        return result.build();
     }
 
     @Override
     public Optional<Metric> remove(MetricName metricName) {
         return Optional.ofNullable(registry.remove(metricName));
     }
 
+    @Override
+    public void addMetrics(Map<String, String> tags, TaggedMetricSet other) {
+        taggedRegistries.put(tags, other);
+    }
+
+    @Override
+    public void removeMetrics(Map<String, String> tags) {
+        taggedRegistries.remove(tags);
+    }
+
     private <T extends Metric> T getOrAdd(MetricName metricName, Class<T> metricClass, Supplier<T> metricSupplier) {
         Metric metric = registry.computeIfAbsent(metricName, name -> metricSupplier.get());
         if (!metricClass.isInstance(metric)) {

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/DropwizardTaggedMetricSet.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2018 Palantir Technologies, Inc. All rights reserved.
+ *
+ * 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 com.palantir.tritium.metrics.registry;
+
+import static java.util.stream.Collectors.toMap;
+
+import com.codahale.metrics.Metric;
+import com.codahale.metrics.MetricRegistry;
+import java.util.Map;
+
+public final class DropwizardTaggedMetricSet implements TaggedMetricSet {
+    private final MetricRegistry metricRegistry;
+
+    public DropwizardTaggedMetricSet(MetricRegistry metricRegistry) {
+        this.metricRegistry = metricRegistry;
+    }
+
+    @Override
+    public Map<MetricName, Metric> getMetrics() {
+        return metricRegistry.getMetrics().entrySet().stream()
+                .collect(toMap(entry -> MetricName.builder().safeName(entry.getKey()).build(), Map.Entry::getValue));
+    }
+}

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/TaggedMetricRegistry.java

@@ -29,7 +29,7 @@
 /**
  * Similar to {@link com.codahale.metrics.MetricRegistry} but allows tagging of {@link Metric}s.
  */
-public interface TaggedMetricRegistry {
+public interface TaggedMetricRegistry extends TaggedMetricSet {
 
     /**
      * Returns existing or new timer metric for the specified metric name.
@@ -81,13 +81,6 @@ public interface TaggedMetricRegistry {
 
     Counter counter(MetricName metricName, Supplier<Counter> counterSupplier);
 
-    /**
-     * Returns a map of registered metrics.
-     *
-     * @return map of registered metrics
-     */
-    Map<MetricName, Metric> getMetrics();
-
     /**
      * Removes the tagged metric with the specified metric name.
      *
@@ -96,4 +89,20 @@ public interface TaggedMetricRegistry {
      */
     Optional<Metric> remove(MetricName metricName);
 
+    /**
+     * Adds a set of metrics to this TaggedMetricRegistry's metric set,
+     * which are to be uniquely identified by the tags provided.
+     * <p>
+     * So, if I have a metric registry with a single metric called 'foo', and I add it
+     * with tag (bar, baz), this registry will now contain 'foo', tagged with (bar, baz).
+     *
+     * @param tags the tags which will be added to all the metrics in the metric set
+     * @param metrics the metrics which should be added
+     */
+    void addMetrics(Map<String, String> tags, TaggedMetricSet metrics);
+
+    /**
+     * Removes a TaggedMetricsSet added via addMetrics from this metrics set.
+     */
+    void removeMetrics(Map<String, String> tags);
 }

tritium-registry/src/main/java/com/palantir/tritium/metrics/registry/TaggedMetricSet.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2018 Palantir Technologies, Inc. All rights reserved.
+ *
+ * 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 com.palantir.tritium.metrics.registry;
+
+import com.codahale.metrics.Metric;
+import java.util.Map;
+
+public interface TaggedMetricSet {
+    /**
+     * Returns a map of metrics.
+     *
+     * @return map of metrics
+     */
+    Map<MetricName, Metric> getMetrics();
+}