add prometheus raw metrics provider support

pulsar-broker/src/main/java/org/apache/pulsar/broker/stats/prometheus/PrometheusMetricsGenerator.java

@@ -31,8 +31,6 @@
 import io.prometheus.client.hotspot.DefaultExports;
 import java.io.IOException;
 import java.io.OutputStream;
-import java.io.StringWriter;
-import java.io.Writer;
 import java.nio.ByteBuffer;
 import java.util.Collection;
 import java.util.Collections;
@@ -51,6 +49,7 @@
 import org.apache.pulsar.broker.stats.metrics.ManagedCursorMetrics;
 import org.apache.pulsar.broker.stats.metrics.ManagedLedgerCacheMetrics;
 import org.apache.pulsar.broker.stats.metrics.ManagedLedgerMetrics;
+import org.apache.pulsar.broker.stats.prometheus.metrics.PrometheusMetricsProvider;
 import org.apache.pulsar.common.stats.Metrics;
 import org.apache.pulsar.common.util.DirectMemoryUtils;
 import org.apache.pulsar.common.util.SimpleTextOutputStream;
@@ -315,12 +314,6 @@ private static void generateManagedLedgerBookieClientMetrics(PulsarService pulsa
             return;
         }
 
-        try {
-            Writer writer = new StringWriter();
-            statsProvider.writeAllMetrics(writer);
-            stream.write(writer.toString());
-        } catch (IOException e) {
-            // nop
-        }
+        ((PrometheusMetricsProvider) statsProvider).generate(stream);
     }
 }

pulsar-broker/src/main/java/org/apache/pulsar/broker/stats/prometheus/metrics/CachingStatsLogger.java

@@ -0,0 +1,138 @@
+/**
+ * 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
+ *
+ *   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 org.apache.pulsar.broker.stats.prometheus.metrics;
+
+import com.google.common.base.Joiner;
+import io.prometheus.client.Collector;
+import java.util.Map;
+import java.util.TreeMap;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import org.apache.bookkeeper.stats.Counter;
+import org.apache.bookkeeper.stats.Gauge;
+import org.apache.bookkeeper.stats.OpStatsLogger;
+import org.apache.bookkeeper.stats.StatsLogger;
+
+/**
+ * A {@code StatsLogger} that caches the stats objects created by other {@code StatsLogger}.
+ */
+public class CachingStatsLogger implements StatsLogger {
+
+    protected final StatsLogger underlying;
+    protected final ConcurrentMap<ScopeContext, Counter> counters;
+    protected final ConcurrentMap<ScopeContext, OpStatsLogger> opStatsLoggers;
+    protected final ConcurrentMap<ScopeContext, StatsLogger> scopeStatsLoggers;
+    protected final ConcurrentMap<ScopeContext, StatsLogger> scopeLabelStatsLoggers;
+
+    private final String scope;
+    private final Map<String, String> labels;
+
+    public CachingStatsLogger(String scope, StatsLogger statsLogger, Map<String, String> labels) {
+        this.scope = scope;
+        this.labels = labels;
+        this.underlying = statsLogger;
+        this.counters = new ConcurrentHashMap<>();
+        this.opStatsLoggers = new ConcurrentHashMap<>();
+        this.scopeStatsLoggers = new ConcurrentHashMap<>();
+        this.scopeLabelStatsLoggers = new ConcurrentHashMap<>();
+    }
+
+    @Override
+    public int hashCode() {
+        return underlying.hashCode();
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof CachingStatsLogger)) {
+            return false;
+        }
+        CachingStatsLogger another = (CachingStatsLogger) obj;
+        return underlying.equals(another.underlying);
+    }
+
+    @Override
+    public String toString() {
+        return underlying.toString();
+    }
+
+    @Override
+    public OpStatsLogger getOpStatsLogger(String name) {
+        return opStatsLoggers.computeIfAbsent(scopeContext(name), x -> underlying.getOpStatsLogger(name));
+    }
+
+    @Override
+    public Counter getCounter(String name) {
+        return counters.computeIfAbsent(scopeContext(name), x -> underlying.getCounter(name));
+    }
+
+    @Override
+    public <T extends Number> void registerGauge(String name, Gauge<T> gauge) {
+        underlying.registerGauge(name, gauge);
+    }
+
+    @Override
+    public <T extends Number> void unregisterGauge(String name, Gauge<T> gauge) {
+        underlying.unregisterGauge(name, gauge);
+    }
+
+    @Override
+    public StatsLogger scope(String name) {
+        return scopeStatsLoggers.computeIfAbsent(scopeContext(name),
+            x -> new CachingStatsLogger(scope, underlying.scope(name), labels));
+    }
+
+    @Override
+    public StatsLogger scopeLabel(String labelName, String labelValue) {
+        Map<String, String> newLabels = new TreeMap<>(labels);
+        newLabels.put(labelName, labelValue);
+        return scopeLabelStatsLoggers.computeIfAbsent(new ScopeContext(completeName(""), newLabels),
+            x -> new CachingStatsLogger(scope, underlying.scopeLabel(labelName, labelValue), newLabels));
+    }
+
+
+    @Override
+    public void removeScope(String name, StatsLogger statsLogger) {
+        scopeStatsLoggers.remove(scopeContext(name), statsLogger);
+    }
+
+    /**
+     Thread-scoped stats not currently supported.
+     */
+    @Override
+    public OpStatsLogger getThreadScopedOpStatsLogger(String name) {
+        return getOpStatsLogger(name);
+    }
+
+    /**
+     Thread-scoped stats not currently supported.
+     */
+    @Override
+    public Counter getThreadScopedCounter(String name) {
+        return getCounter(name);
+    }
+
+    private ScopeContext scopeContext(String name) {
+        return new ScopeContext(completeName(name), labels);
+    }
+
+    private String completeName(String name) {
+        return Collector.sanitizeMetricName(scope.isEmpty() ? name : Joiner.on('_').join(scope, name));
+    }
+}

pulsar-broker/src/main/java/org/apache/pulsar/broker/stats/prometheus/metrics/CachingStatsProvider.java

@@ -0,0 +1,64 @@
+/**
+ * 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
+ *
+ *   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 org.apache.pulsar.broker.stats.prometheus.metrics;
+
+import java.util.Collections;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import org.apache.bookkeeper.stats.StatsLogger;
+import org.apache.bookkeeper.stats.StatsProvider;
+import org.apache.commons.configuration.Configuration;
+
+/**
+ * A {@code CachingStatsProvider} adds the caching functionality to an existing {@code StatsProvider}.
+ *
+ * <p>The stats provider will cache the stats objects created by the other {@code StatsProvider} to allow
+ * the reusability of stats objects and avoid creating a lot of stats objects.
+ */
+public class CachingStatsProvider implements StatsProvider {
+
+    protected final StatsProvider underlying;
+    protected final ConcurrentMap<String, StatsLogger> statsLoggers;
+
+    public CachingStatsProvider(StatsProvider provider) {
+        this.underlying = provider;
+        this.statsLoggers = new ConcurrentHashMap<>();
+    }
+
+    @Override
+    public void start(Configuration conf) {
+        this.underlying.start(conf);
+    }
+
+    @Override
+    public void stop() {
+        this.underlying.stop();
+    }
+
+    @Override
+    public StatsLogger getStatsLogger(String scope) {
+        return statsLoggers.computeIfAbsent(scope,
+            x -> new CachingStatsLogger(scope, underlying.getStatsLogger(scope), Collections.emptyMap()));
+    }
+
+    @Override
+    public String getStatsName(String... statsComponents) {
+        return underlying.getStatsName(statsComponents);
+    }
+}

pulsar-broker/src/main/java/org/apache/pulsar/broker/stats/prometheus/metrics/DataSketchesOpStatsLogger.java

@@ -54,9 +54,15 @@ public class DataSketchesOpStatsLogger implements OpStatsLogger {
     private final LongAdder successSumAdder = new LongAdder();
     private final LongAdder failSumAdder = new LongAdder();
 
-    public DataSketchesOpStatsLogger() {
+    private Map<String, String> labels;
+
+    // used for lazy registration for thread scoped metrics
+    private boolean threadInitialized;
+
+    public DataSketchesOpStatsLogger(Map<String, String> labels) {
         this.current = new ThreadLocalAccessor();
         this.replacement = new ThreadLocalAccessor();
+        this.labels = labels;
     }
 
     @Override
@@ -172,6 +178,19 @@ public double getQuantileValue(boolean success, double quantile) {
         return s != null ? s.getQuantile(quantile) : Double.NaN;
     }
 
+    public Map<String, String> getLabels() {
+        return labels;
+    }
+
+    public boolean isThreadInitialized() {
+        return threadInitialized;
+    }
+
+    public void initializeThread(Map<String, String> labels) {
+        this.labels = labels;
+        this.threadInitialized = true;
+    }
+
     private static class LocalData {
         private final DoublesSketch successSketch = new DoublesSketchBuilder().build();
         private final DoublesSketch failSketch = new DoublesSketchBuilder().build();

pulsar-broker/src/main/java/org/apache/pulsar/broker/stats/prometheus/metrics/LongAdderCounter.java

@@ -18,6 +18,7 @@
  */
 package org.apache.pulsar.broker.stats.prometheus.metrics;
 
+import java.util.Map;
 import java.util.concurrent.atomic.LongAdder;
 import org.apache.bookkeeper.stats.Counter;
 
@@ -30,8 +31,13 @@
 public class LongAdderCounter implements Counter {
     private final LongAdder counter = new LongAdder();
 
-    public LongAdderCounter() {
+    private Map<String, String> labels;
 
+    // used for lazy registration for thread scoped metric
+    private boolean threadInitialized;
+
+    public LongAdderCounter(Map<String, String> labels) {
+        this.labels = labels;
     }
 
     @Override
@@ -58,4 +64,17 @@ public void add(long delta) {
     public Long get() {
         return counter.sum();
     }
+
+    public Map<String, String> getLabels() {
+        return labels;
+    }
+
+    public boolean isThreadInitialized() {
+        return threadInitialized;
+    }
+
+    public void initializeThread(Map<String, String> labels) {
+        this.labels = labels;
+        this.threadInitialized = true;
+    }
 }