Add basic metrics support

apm-agent-api/src/main/java/co/elastic/apm/api/AbstractSpanImpl.java

@@ -7,9 +7,9 @@
  * 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.

apm-agent-core/src/main/java/co/elastic/apm/agent/configuration/CoreConfiguration.java

@@ -36,6 +36,8 @@
 import java.util.Set;
 import java.util.TreeSet;
 
+import static co.elastic.apm.agent.configuration.validation.RangeValidator.isInRange;
+
 public class CoreConfiguration extends ConfigurationOptionProvider {
 
     public static final String ACTIVE = "active";
@@ -102,16 +104,7 @@ public class CoreConfiguration extends ConfigurationOptionProvider {
             "To reduce overhead and storage requirements, you can set the sample rate to a value between 0.0 and 1.0. " +
             "We still record overall time and the result for unsampled transactions, but no context information, tags, or spans.")
         .dynamic(true)
-        .addValidator(new ConfigurationOption.Validator<Double>() {
-            @Override
-            public void assertValid(Double value) {
-                if (value != null) {
-                    if (value < 0 || value > 1) {
-                        throw new IllegalArgumentException("The sample rate must be between 0 and 1");
-                    }
-                }
-            }
-        })
+        .addValidator(isInRange(0d, 1d))
         .buildWithDefault(1.0);
 
     private final ConfigurationOption<Integer> transactionMaxSpans = ConfigurationOption.integerOption()

apm-agent-core/src/main/java/co/elastic/apm/agent/configuration/converter/TimeDuration.java

@@ -22,7 +22,7 @@
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-public class TimeDuration {
+public class TimeDuration implements Comparable<TimeDuration> {
 
     public static final Pattern DURATION_PATTERN = Pattern.compile("^(-)?(\\d+)(ms|s|m)$");
     private final String durationString;
@@ -68,4 +68,9 @@ public long getMillis() {
     public String toString() {
         return durationString;
     }
+
+    @Override
+    public int compareTo(TimeDuration o) {
+        return Long.compare(durationMs, o.durationMs);
+    }
 }

apm-agent-core/src/main/java/co/elastic/apm/agent/configuration/validation/RangeValidator.java

@@ -0,0 +1,76 @@
+/*-
+ * #%L
+ * Elastic APM Java agent
+ * %%
+ * Copyright (C) 2018 Elastic and contributors
+ * %%
+ * 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.
+ * #L%
+ */
+package co.elastic.apm.agent.configuration.validation;
+
+import org.stagemonitor.configuration.ConfigurationOption;
+
+import javax.annotation.Nullable;
+
+public class RangeValidator<T extends Comparable> implements ConfigurationOption.Validator<T> {
+
+    @Nullable
+    private final T min;
+    @Nullable
+    private final T max;
+    private final boolean mustBeInRange;
+
+    private RangeValidator(@Nullable T min, @Nullable T max, boolean mustBeInRange) {
+        this.min = min;
+        this.max = max;
+        this.mustBeInRange = mustBeInRange;
+    }
+
+    public static <T extends Comparable> RangeValidator<T> isInRange(T min, T max) {
+        return new RangeValidator<>(min, max, true);
+    }
+
+    public static <T extends Comparable> RangeValidator<T> isNotInRange(T min, T max) {
+        return new RangeValidator<>(min, max, false);
+    }
+
+    public static <T extends Comparable> RangeValidator<T> min(T min) {
+        return new RangeValidator<>(min, null, true);
+    }
+
+    public static <T extends Comparable> RangeValidator<T> max(T max) {
+        return new RangeValidator<>(null, max, true);
+    }
+
+    @Override
+    public void assertValid(@Nullable T value) {
+        if (value != null) {
+            boolean isInRange = true;
+            if (min != null) {
+                isInRange = min.compareTo(value) <= 0;
+            }
+            if (max != null) {
+                isInRange &= value.compareTo(max) <= 0;
+            }
+
+            if (!isInRange && mustBeInRange) {
+                throw new IllegalArgumentException(value + " must be in the range [" + min + "," + max + "]");
+            }
+
+            if (isInRange && !mustBeInRange) {
+                throw new IllegalArgumentException(value + " must not be in the range [" + min + "," + max + "]");
+            }
+        }
+    }
+}

apm-agent-core/src/main/java/co/elastic/apm/agent/impl/ElasticApmTracer.java

@@ -29,8 +29,9 @@
 import co.elastic.apm.agent.impl.transaction.Span;
 import co.elastic.apm.agent.impl.transaction.TraceContext;
 import co.elastic.apm.agent.impl.transaction.Transaction;
-import co.elastic.apm.agent.objectpool.ObjectPool;
+import co.elastic.apm.agent.metrics.MetricRegistry;
 import co.elastic.apm.agent.objectpool.Allocator;
+import co.elastic.apm.agent.objectpool.ObjectPool;
 import co.elastic.apm.agent.objectpool.impl.QueueBasedObjectPool;
 import co.elastic.apm.agent.report.Reporter;
 import co.elastic.apm.agent.report.ReporterConfiguration;
@@ -75,6 +76,7 @@ protected Deque<Object> initialValue() {
     };
     private final CoreConfiguration coreConfiguration;
     private final List<SpanListener> spanListeners;
+    private final MetricRegistry metricRegistry = new MetricRegistry();
     private Sampler sampler;
 
     ElasticApmTracer(ConfigurationRegistry configurationRegistry, Reporter reporter, Iterable<LifecycleListener> lifecycleListeners, List<SpanListener> spanListeners) {
@@ -120,6 +122,7 @@ public void onChange(ConfigurationOption<?> configurationOption, Double oldValue
         for (SpanListener spanListener : spanListeners) {
             spanListener.init(this);
         }
+        reporter.scheduleMetricReporting(metricRegistry, configurationRegistry.getConfig(ReporterConfiguration.class).getMetricsIntervalMs());
     }
 
     public Transaction startTransaction() {
@@ -396,4 +399,8 @@ private void assertIsActive(Object span, @Nullable Object currentlyActive) {
         }
         assert span == currentlyActive;
     }
+
+    public MetricRegistry getMetricRegistry() {
+        return metricRegistry;
+    }
 }

apm-agent-core/src/main/java/co/elastic/apm/agent/report/PayloadSender.java → apm-agent-core/src/main/java/co/elastic/apm/agent/metrics/DoubleSupplier.java

@@ -17,14 +17,9 @@
  * limitations under the License.
  * #L%
  */
-package co.elastic.apm.agent.report;
+package co.elastic.apm.agent.metrics;
 
-import co.elastic.apm.agent.impl.payload.Payload;
+public interface DoubleSupplier {
 
-public interface PayloadSender {
-    void sendPayload(Payload payload);
-
-    long getReported();
-
-    long getDropped();
+    double get();
 }

apm-agent-core/src/main/java/co/elastic/apm/agent/metrics/MetricRegistry.java

@@ -0,0 +1,110 @@
+/*-
+ * #%L
+ * Elastic APM Java agent
+ * %%
+ * Copyright (C) 2018 Elastic and contributors
+ * %%
+ * 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.
+ * #L%
+ */
+package co.elastic.apm.agent.metrics;
+
+import co.elastic.apm.agent.report.serialize.MetricRegistrySerializer;
+import com.dslplatform.json.DslJson;
+import com.dslplatform.json.JsonWriter;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * A registry for metrics.
+ * <p>
+ * Currently only holds gauges.
+ * There are plans to add support for histogram-based timers.
+ * </p>
+ */
+public class MetricRegistry {
+
+    /**
+     * Groups {@link MetricSet}s by their unique tags.
+     */
+    private final ConcurrentMap<Map<String, String>, MetricSet> metricSets = new ConcurrentHashMap<>();
+
+    /**
+     * Same as {@link #add(String, Map, DoubleSupplier)} but only adds the metric
+     * if the {@link DoubleSupplier} does not return {@link Double#NaN}
+     *
+     * @param name   the name of the metric
+     * @param tags   tags for the metric.
+     *               Tags can be used to create different graphs based for each value of a specific tag name, using a terms aggregation.
+     *               Note that there will be a {@link MetricSet} created for each distinct set of tags.
+     * @param metric this supplier will be called for every reporting cycle
+     *               ({@link co.elastic.apm.agent.report.ReporterConfiguration#metricsInterval metrics_interval)})
+     * @see #add(String, Map, DoubleSupplier)
+     */
+    public void addUnlessNan(String name, Map<String, String> tags, DoubleSupplier metric) {
+        if (!Double.isNaN(metric.get())) {
+            add(name, tags, metric);
+        }
+    }
+
+    /**
+     * Same as {@link #add(String, Map, DoubleSupplier)} but only adds the metric
+     * if the {@link DoubleSupplier} returns a positive number or zero.
+     *
+     * @param name   the name of the metric
+     * @param tags   tags for the metric.
+     *               Tags can be used to create different graphs based for each value of a specific tag name, using a terms aggregation.
+     *               Note that there will be a {@link MetricSet} created for each distinct set of tags.
+     * @param metric this supplier will be called for every reporting cycle
+     *               ({@link co.elastic.apm.agent.report.ReporterConfiguration#metricsInterval metrics_interval)})
+     * @see #add(String, Map, DoubleSupplier)
+     */
+    public void addUnlessNegative(String name, Map<String, String> tags, DoubleSupplier metric) {
+        if (metric.get() >= 0) {
+            add(name, tags, metric);
+        }
+    }
+
+    /**
+     * Adds a gauge to the metric registry.
+     *
+     * @param name   the name of the metric
+     * @param tags   tags for the metric.
+     *               Tags can be used to create different graphs based for each value of a specific tag name, using a terms aggregation.
+     *               Note that there will be a {@link MetricSet} created for each distinct set of tags.
+     * @param metric this supplier will be called for every reporting cycle
+     *               ({@link co.elastic.apm.agent.report.ReporterConfiguration#metricsInterval metrics_interval)})
+     */
+    public void add(String name, Map<String, String> tags, DoubleSupplier metric) {
+        MetricSet metricSet = metricSets.get(tags);
+        if (metricSet == null) {
+            metricSets.putIfAbsent(tags, new MetricSet(tags));
+            metricSet = metricSets.get(tags);
+        }
+        metricSet.add(name, metric);
+    }
+
+    public double get(String name, Map<String, String> tags) {
+        final MetricSet metricSet = metricSets.get(tags);
+        if (metricSet != null) {
+            return metricSet.get(name).get();
+        }
+        return Double.NaN;
+    }
+
+    public Map<Map<String, String>, MetricSet> getMetricSets() {
+        return metricSets;
+    }
+}

apm-agent-core/src/main/java/co/elastic/apm/agent/metrics/MetricSet.java

@@ -0,0 +1,63 @@
+/*-
+ * #%L
+ * Elastic APM Java agent
+ * %%
+ * Copyright (C) 2018 Elastic and contributors
+ * %%
+ * 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.
+ * #L%
+ */
+package co.elastic.apm.agent.metrics;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * A metric set is a collection of metrics which have the same tags.
+ * <p>
+ * A metric set corresponds to one document per
+ * {@link co.elastic.apm.agent.report.ReporterConfiguration#metricsInterval metrics_interval} in Elasticsearch.
+ * An alternative would be to have one document per metric but having one document for all metrics with the same tags saves disk space.
+ * </p>
+ * Example of some serialized metric sets:
+ * <pre>
+ * {"metricset":{"timestamp":1545047730692000,"samples":{"jvm.gc.alloc":{"value":24089200.0}}}}
+ * {"metricset":{"timestamp":1545047730692000,"tags":{"name":"G1 Young Generation"},"samples":{"jvm.gc.time":{"value":0.0},"jvm.gc.count":{"value":0.0}}}}
+ * {"metricset":{"timestamp":1545047730692000,"tags":{"name":"G1 Old Generation"},  "samples":{"jvm.gc.time":{"value":0.0},"jvm.gc.count":{"value":0.0}}}}
+ * </pre>
+ */
+public class MetricSet {
+    private final Map<String, String> tags;
+    private final ConcurrentMap<String, DoubleSupplier> samples = new ConcurrentHashMap<>();
+
+    public MetricSet(Map<String, String> tags) {
+        this.tags = tags;
+    }
+
+    public void add(String name, DoubleSupplier metric) {
+        samples.putIfAbsent(name, metric);
+    }
+
+    DoubleSupplier get(String name) {
+        return samples.get(name);
+    }
+
+    public Map<String, String> getTags() {
+        return tags;
+    }
+
+    public Map<String, DoubleSupplier> getSamples() {
+        return samples;
+    }
+}