com.datastax.oss.driver.api.core.metrics.Metrics Maven / Gradle / Ivy
/*
* Copyright DataStax, Inc.
*
* 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.datastax.oss.driver.api.core.metrics;
import com.codahale.metrics.Metric;
import com.codahale.metrics.MetricRegistry;
import com.datastax.oss.driver.api.core.metadata.Node;
import edu.umd.cs.findbugs.annotations.NonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.util.Optional;
/**
* A wrapper around a {@link MetricRegistry} to expose the driver's metrics.
*
* This type exists mainly to avoid a hard dependency to Dropwizard Metrics (that is, the JAR can
* be completely removed from the classpath if metrics are disabled). It also provides convenience
* methods to access individual metrics programmatically.
*/
public interface Metrics {
/**
* Returns the underlying Dropwizard registry.
*
*
Typically, this can be used to configure a reporter.
*
* @see Reporters
* (Dropwizard Metrics manual)
* @leaks-private-api
*/
@NonNull
MetricRegistry getRegistry();
/**
* Retrieves a session-level metric from the registry.
*
*
To determine the type of each metric, refer to the comments in the default {@code
* reference.conf} (included in the driver's codebase and JAR file). Note that the method does not
* check that this type is correct (there is no way to do this at runtime because some metrics are
* generic); if you use the wrong type, you will get a {@code ClassCastException} in your code:
*
*
{@code
* // Correct:
* Gauge connectedNodes = getSessionMetric(DefaultSessionMetric.CONNECTED_NODES);
*
* // Wrong, will throw CCE:
* Counter connectedNodes = getSessionMetric(DefaultSessionMetric.CONNECTED_NODES);
* }
*
* @param profileName the name of the execution profile, or {@code null} if the metric is not
* associated to any profile. Note that this is only included for future extensibility: at
* this time, the driver does not break up metrics per profile. Therefore you can always use
* {@link #getSessionMetric(SessionMetric)} instead of this method.
* @return the metric, or empty if it is disabled.
*/
@SuppressWarnings("TypeParameterUnusedInFormals")
@NonNull
Optional getSessionMetric(
@NonNull SessionMetric metric, @Nullable String profileName);
/**
* Shortcut for {@link #getSessionMetric(SessionMetric, String) getSessionMetric(metric, null)}.
*/
@SuppressWarnings("TypeParameterUnusedInFormals")
@NonNull
default Optional getSessionMetric(@NonNull SessionMetric metric) {
return getSessionMetric(metric, null);
}
/**
* Retrieves a node-level metric for a given node from the registry.
*
* To determine the type of each metric, refer to the comments in the default {@code
* reference.conf} (included in the driver's codebase and JAR file). Note that the method does not
* check that this type is correct (there is no way to do this at runtime because some metrics are
* generic); if you use the wrong type, you will get a {@code ClassCastException} in your code:
*
*
{@code
* // Correct:
* Gauge openConnections = getNodeMetric(node, DefaultNodeMetric.OPEN_CONNECTIONS);
*
* // Wrong, will throw CCE:
* Counter openConnections = getNodeMetric(node, DefaultNodeMetric.OPEN_CONNECTIONS);
* }
*
* @param profileName the name of the execution profile, or {@code null} if the metric is not
* associated to any profile. Note that this is only included for future extensibility: at
* this time, the driver does not break up metrics per profile. Therefore you can always use
* {@link #getNodeMetric(Node, NodeMetric)} instead of this method.
* @return the metric, or empty if it is disabled.
*/
@SuppressWarnings("TypeParameterUnusedInFormals")
@NonNull
Optional getNodeMetric(
@NonNull Node node, @NonNull NodeMetric metric, @Nullable String profileName);
/**
* Shortcut for {@link #getNodeMetric(Node, NodeMetric, String) getNodeMetric(node, metric,
* null)}.
*/
@SuppressWarnings("TypeParameterUnusedInFormals")
@NonNull
default Optional getNodeMetric(
@NonNull Node node, @NonNull NodeMetric metric) {
return getNodeMetric(node, metric, null);
}
}