allow to configure Reservoir implementations

introduction of a setting in the MetricsConfiguration class
to be able to configure the Reservoir implementation to use for
produced Timer & Histogram instances.

see #12

envs/se/src/main/java/io/astefanutti/metrics/cdi/se/ReservoirBuilderNullContributor.java

@@ -0,0 +1,48 @@
+/**
+ * Copyright © 2013 Antonin Stefanutti (antonin.stefanutti@gmail.com)
+ *
+ * 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.astefanutti.metrics.cdi.se;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import javax.enterprise.context.ApplicationScoped;
+import javax.enterprise.event.Observes;
+
+import com.codahale.metrics.Reservoir;
+import com.codahale.metrics.SlidingTimeWindowArrayReservoir;
+
+import io.astefanutti.metrics.cdi.MetricsConfiguration;
+import io.astefanutti.metrics.cdi.ReservoirBuidler;
+import io.astefanutti.metrics.cdi.ReservoirUsage;
+
+@ApplicationScoped
+public class ReservoirBuilderNullContributor {
+    AtomicInteger counter = new AtomicInteger();
+
+    public int calls() {
+        return counter.get();
+    }
+
+    void configuration(@Observes MetricsConfiguration configuration) {
+        configuration.useReservoirBuilder(new ReservoirBuidler() {
+            @Override
+            public Reservoir build(String metricName, ReservoirUsage type) {
+                counter.incrementAndGet();
+                return null;
+            }
+        });
+    }
+}

envs/se/src/test/java/io/astefanutti/metrics/cdi/se/ReservoirBuilderTest.java

@@ -0,0 +1,69 @@
+/**
+ * Copyright © 2013 Antonin Stefanutti (antonin.stefanutti@gmail.com)
+ *
+ * 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.astefanutti.metrics.cdi.se;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import javax.inject.Inject;
+
+import org.jboss.arquillian.container.test.api.Deployment;
+import org.jboss.arquillian.junit.Arquillian;
+import org.jboss.shrinkwrap.api.Archive;
+import org.jboss.shrinkwrap.api.ShrinkWrap;
+import org.jboss.shrinkwrap.api.asset.EmptyAsset;
+import org.jboss.shrinkwrap.api.spec.JavaArchive;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import io.astefanutti.metrics.cdi.MetricsExtension;
+
+@RunWith(Arquillian.class)
+public class ReservoirBuilderTest {
+    @Inject
+    ReservoirBuilderNullContributor reservoirBuilder;
+
+    @Inject
+    TimerFieldBean timerBean;
+
+    @Inject
+    HistogramFieldBean histogramBean;
+
+
+    @Deployment
+    public static Archive<?> createTestArchive() {
+        return ShrinkWrap.create(JavaArchive.class)
+                // Test bean class with Timer injection
+                .addClass(TimerFieldBean.class)
+                // Test bean class with Histogram injection
+                .addClass(HistogramFieldBean.class)
+                // The ReservoirBuilder counting calls
+                .addClass(ReservoirBuilderNullContributor.class)
+                // Metrics CDI extension
+                .addPackage(MetricsExtension.class.getPackage())
+                // Bean archive deployment descriptor
+                .addAsManifestResource(EmptyAsset.INSTANCE, "beans.xml");
+    }
+
+    @Test
+    public void checkReservoirBuilderCalls() {
+        int NB_TIMER_FIELDS_IN_BEAN = 6;
+        int NB_HISTOGRAM_FIELDS_IN_BEAN = 1;
+
+        int expectedCalls = NB_TIMER_FIELDS_IN_BEAN + NB_HISTOGRAM_FIELDS_IN_BEAN;
+        assertThat("Number of ReservoirBuilder calls differ from expected # of Timer fields", reservoirBuilder.calls(), is(expectedCalls));
+    } 
+}

impl/src/main/java/io/astefanutti/metrics/cdi/MetricProducer.java

@@ -20,6 +20,7 @@
 import com.codahale.metrics.Histogram;
 import com.codahale.metrics.Meter;
 import com.codahale.metrics.MetricRegistry;
+import com.codahale.metrics.Reservoir;
 import com.codahale.metrics.Timer;
 
 import javax.annotation.Priority;
@@ -53,8 +54,25 @@ public T getValue() {
     }
 
     @Produces
-    private static Histogram histogram(InjectionPoint ip, MetricRegistry registry, MetricName metricName) {
-        return registry.histogram(metricName.of(ip));
+    private static Histogram histogram(InjectionPoint ip, MetricRegistry registry, MetricName metricName, MetricsExtension extension) {
+        String histogramName = metricName.of(ip);
+        Reservoir reservoir = null;
+        ReservoirBuidler reservoirBuidler = extension.getReservoirBuidler();
+        if (reservoirBuidler != null) {
+            reservoir = reservoirBuidler.build(histogramName, ReservoirUsage.HISTOGRAM);
+        }
+
+        if (reservoir == null) {
+            return registry.histogram(histogramName);
+        } else {
+            final Reservoir r = reservoir;
+            return registry.histogram(histogramName, new MetricRegistry.MetricSupplier<Histogram>() {
+                @Override
+                public Histogram newMetric() {
+                    return new Histogram(r);
+                }
+            });
+        }
     }
 
     @Produces
@@ -63,7 +81,24 @@ private static Meter meter(InjectionPoint ip, MetricRegistry registry, MetricNam
     }
 
     @Produces
-    private static Timer timer(InjectionPoint ip, MetricRegistry registry, MetricName metricName) {
-        return registry.timer(metricName.of(ip));
+    private static Timer timer(InjectionPoint ip, MetricRegistry registry, MetricName metricName, MetricsExtension extension) {
+        String timerName = metricName.of(ip);
+        Reservoir reservoir = null;
+        ReservoirBuidler reservoirBuidler = extension.getReservoirBuidler();
+        if (reservoirBuidler != null) {
+            reservoir = reservoirBuidler.build(timerName, ReservoirUsage.TIMER);
+        }
+
+        if (reservoir == null) {
+            return registry.timer(timerName);
+        } else {
+            final Reservoir r = reservoir;
+            return registry.timer(timerName, new MetricRegistry.MetricSupplier<Timer>() {
+                @Override
+                public Timer newMetric() {
+                    return new Timer(r);
+                }
+            });
+        }
     }
 }

impl/src/main/java/io/astefanutti/metrics/cdi/MetricsConfiguration.java

@@ -30,4 +30,12 @@ public interface MetricsConfiguration {
      * @throws IllegalStateException if called outside of the observer method invocation
      */
     MetricsConfiguration useAbsoluteName(boolean useAbsoluteName);
+
+    /**
+     * Registers a builder to produce different {@link com.codahale.metrics.Reservoir} implementations depending on the metric. 
+     * @param builder the builder to use to produce {@link com.codahale.metrics.Reservoir} instances
+     * @return this Metrics CDI configuration
+     * @throws IllegalStateException if called outside of the observer method invocation
+     */
+    MetricsConfiguration useReservoirBuilder(ReservoirBuidler builder);
 }

impl/src/main/java/io/astefanutti/metrics/cdi/MetricsConfigurationEvent.java

@@ -20,10 +20,13 @@
 import java.util.EnumSet;
 import java.util.Set;
 
+import com.codahale.metrics.Reservoir;
+
 /* package-private */ final class MetricsConfigurationEvent implements MetricsConfiguration {
 
     private final EnumSet<MetricsParameter> configuration = EnumSet.noneOf(MetricsParameter.class);
 
+    private ReservoirBuidler reservoirBuilder;
     private volatile boolean unmodifiable;
 
     @Override
@@ -36,10 +39,21 @@ public MetricsConfiguration useAbsoluteName(boolean useAbsoluteName) {
         return this;
     }
 
+    @Override
+    public MetricsConfiguration useReservoirBuilder(ReservoirBuidler builder) {
+        throwsIfUnmodifiable();
+        this.reservoirBuilder = builder;
+        return this;
+    }
+
     Set<MetricsParameter> getParameters() {
         return Collections.unmodifiableSet(configuration);
     }
 
+    ReservoirBuidler getReservoirBuilder() {
+        return reservoirBuilder;
+    }
+
     void unmodifiable() {
         unmodifiable = true;
     }

impl/src/main/java/io/astefanutti/metrics/cdi/MetricsExtension.java

@@ -69,6 +69,10 @@ public class MetricsExtension implements Extension {
     Set<MetricsParameter> getParameters() {
         return configuration.getParameters();
     }
+
+    ReservoirBuidler getReservoirBuidler() { 
+        return configuration.getReservoirBuilder();
+    }
 
     private void addInterceptorBindings(@Observes BeforeBeanDiscovery bbd, BeanManager manager) {
         declareAsInterceptorBinding(Counted.class, manager, bbd);

impl/src/main/java/io/astefanutti/metrics/cdi/ReservoirBuidler.java

@@ -0,0 +1,31 @@
+/**
+ * Copyright © 2013 Antonin Stefanutti (antonin.stefanutti@gmail.com)
+ *
+ * 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.astefanutti.metrics.cdi;
+
+import com.codahale.metrics.Reservoir;
+
+/**
+ * Builder class allowing the production of different {@link Reservoir} implementations based on the metric kind & names.
+ */
+public interface ReservoirBuidler {
+    /**
+     * Builds a {@link Reservoir} for the given metric
+     * @param metricName the name of the metric for which a Reservoir needs to be used
+     * @param type the kind of metric for which a reservoir is required
+     * @return the reservoir to use, or null if default reservoir implementation has to be used
+     */
+    Reservoir build(String metricName, ReservoirUsage type);
+}

impl/src/main/java/io/astefanutti/metrics/cdi/ReservoirUsage.java

@@ -0,0 +1,20 @@
+/**
+ * Copyright © 2013 Antonin Stefanutti (antonin.stefanutti@gmail.com)
+ *
+ * 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.astefanutti.metrics.cdi;
+
+public enum ReservoirUsage {
+    HISTOGRAM, TIMER;
+}