Metrics (Diffusion)

All Superinterfaces:

Feature
```
public interface Metrics
extends Feature
```
This feature allows a client to configure metric collectors.
Diffusion servers provide metrics which are made available in several ways:-
- Java Management Extensions (JMX) MBeans.
- Through the Diffusion Management Console.
- As endpoints for Prometheus.
Metric collectors allow custom aggregation of metrics that are relevant to your application. There are no default metric collectors, only the ones that you create.
There are two types of metric collector: Session Metric Collectors and Topic Metric Collectors.
For full details regarding the configuration and operation of metric collectors see the user manual.
Session Metric Collectors.

These can be configured to record metric data for a subset of all sessions, specified with a session filter.
The set of metrics recorded by each session metric collector is the same as those recorded for the whole server. For full details of session metrics, see the table in user manual.
If the session filters of two different session metric collectors select the same session, both will record metrics for that session. It is only valid to add the metrics of different session metric collectors if their session filters select distinct sets of sessions.
You can optionally group the sessions within a collector by session properties.
Topic Metric Collectors

These can be configured to record metric data for a subset of all topics, specified with a topic selector.
You can optionally group the topics within a collector by topic type.
The set of metrics recorded by each topic metric collector is the same as those recorded for the whole server. For full details of topic metrics, see the table in the user manual.
If the topic selectors of two different topic metric collectors select the same topic, both will record metrics for that topic. It is only valid to add the metrics of different topic metric collectors if their topic selectors select distinct sets of topics.
Access control

The following access control restrictions are applied:
- To put or remove a session metric collector, a session needs the CONTROL_SERVER global permission.
- To put or remove a topic metric collector, a session needs the CONTROL_SERVER global permission.
- To list session metric collectors or topic metric collectors, a session needs the VIEW_SERVER global permission.
- To get metrics with Metrics.MetricsRequest.fetch(), session needs the VIEW_SERVER global permission.
Accessing the feature

This feature may be obtained from a session as follows:
```
 Metrics metrics = session.feature(Metrics.class);
 
```
Since:

6.7

Nested Class Summary

Nested Classes
Modifier and Type	Interface and Description
`static interface`	`Metrics.Builder<B extends Metrics.Builder<B>>` Common interface for metric collector builders.
`static interface`	`Metrics.MetricCollector` The common base interface for metric collectors.
`static interface`	`Metrics.MetricSample` Represents a single metric sample.
`static interface`	`Metrics.MetricSampleCollection` Represents a collection of metric samples.
`static interface`	`Metrics.MetricsRequest` A parameterized query that can be used to fetch metrics from the server.
`static interface`	`Metrics.MetricsResult` The result of a fetch metrics operation, initiated by a `Metrics.MetricsRequest`.
`static class`	`Metrics.MetricType` Enumeration defining the metric types available.
`static interface`	`Metrics.SessionMetricCollector` The definition of a session metric collector.
`static interface`	`Metrics.TopicMetricCollector` The definition of a topic metric collector.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`CompletableFuture<List<Metrics.SessionMetricCollector>>`	`listSessionMetricCollectors()` Retrieves the current session metric collectors.
`CompletableFuture<List<Metrics.TopicMetricCollector>>`	`listTopicMetricCollectors()` Retrieves the current topic metric collectors.
`Metrics.MetricsRequest`	`metricsRequest()` Creates an unconfigured `Metrics.MetricsRequest`.
`CompletableFuture<?>`	`putSessionMetricCollector(Metrics.SessionMetricCollector collector)` Add a session metric collector, replacing any with the same name.
`CompletableFuture<?>`	`putTopicMetricCollector(Metrics.TopicMetricCollector collector)` Add a topic metric collector, replacing any with the same name.
`CompletableFuture<?>`	`removeSessionMetricCollector(String name)` Removes any session metric collector with the given name, if it exists.
`CompletableFuture<?>`	`removeTopicMetricCollector(String name)` Removes any topic metric collector with the given name, if it exists.

Methods inherited from interface com.pushtechnology.diffusion.client.session.Feature
getSession

- Method Detail
  - putSessionMetricCollector
```
CompletableFuture<?> putSessionMetricCollector(Metrics.SessionMetricCollector collector)
```
    Add a session metric collector, replacing any with the same name.
    Parameters:
    
    collector - the session metric collector
    
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be null. The result type is any rather than Void to provide forward compatibility with future iterations of this API that may provide a non-null result with a more specific result type.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    InvalidFilterException – if the metric collector session filter is invalid;
    PermissionsException – if the calling session does not have CONTROL_SERVER permission;
    ClusterRoutingException – if the operation failed due to a transient cluster error;
    SessionClosedException – if the session is closed.
  - listSessionMetricCollectors
```
CompletableFuture<List<Metrics.SessionMetricCollector>> listSessionMetricCollectors()
```
    Retrieves the current session metric collectors.
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be a list of current session metric collectors.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    PermissionsException – if the calling session does not have VIEW_SERVER permission;
    SessionClosedException – if the session is closed.
  - removeSessionMetricCollector
```
CompletableFuture<?> removeSessionMetricCollector(String name)
```
    Removes any session metric collector with the given name, if it exists.
    Parameters:
    
    name - the session metric collector name
    
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be null. The result type is any rather than Void to provide forward compatibility with future iterations of this API that may provide a non-null result with a more specific result type.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    PermissionsException – if the calling session does not have CONTROL_SERVER permission;
    ClusterRoutingException – if the operation failed due to a transient cluster error;
    SessionClosedException – if the session is closed.
  - putTopicMetricCollector
```
CompletableFuture<?> putTopicMetricCollector(Metrics.TopicMetricCollector collector)
```
    Add a topic metric collector, replacing any with the same name.
    A Metrics.TopicMetricCollector instance can be created using newTopicMetricCollectorBuilder.
    Parameters:
    
    collector - the topic metric collector
    
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be null. The result type is any rather than Void to provide forward compatibility with future iterations of this API that may provide a non-null result with a more specific result type.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    PermissionsException – if the calling session does not have CONTROL_SERVER permission;
    ClusterRoutingException – if the operation failed due to a transient cluster error;
    SessionClosedException – if the session is closed.
  - listTopicMetricCollectors
```
CompletableFuture<List<Metrics.TopicMetricCollector>> listTopicMetricCollectors()
```
    Retrieves the current topic metric collectors.
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be a list of current topic metric collectors.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    PermissionsException – if the calling session does not have VIEW_SERVER permission;
    SessionClosedException – if the session is closed.
  - removeTopicMetricCollector
```
CompletableFuture<?> removeTopicMetricCollector(String name)
```
    Removes any topic metric collector with the given name, if it exists.
    Parameters:
    
    name - the topic metric collector name
    
    Returns:
    a CompletableFuture that completes when a response is received from the server.
    If the task completes successfully, the CompletableFuture result will be null. The result type is any rather than Void to provide forward compatibility with future iterations of this API that may provide a non-null result with a more specific result type.
    Otherwise, the CompletableFuture will complete exceptionally with a CompletionException. Common reasons for failure, listed by the exception reported as the cause, include:
    
    PermissionsException – if the calling session does not have CONTROL_SERVER permission;
    ClusterRoutingException – if the operation failed due to a transient cluster error;
    SessionClosedException – if the session is closed.
  - metricsRequest
```
Metrics.MetricsRequest metricsRequest()
```
    Creates an unconfigured Metrics.MetricsRequest. The request can be invoked using Metrics.MetricsRequest.fetch() to retrieve metrics for the server or cluster.
    See Metrics.MetricsRequest for more information.
    
    Returns:
    
    a new Metrics.MetricsRequest
    
    Since:
    
    6.10

Interface Metrics

Session Metric Collectors.

Topic Metric Collectors

Access control

Accessing the feature

Nested Class Summary

Method Summary

Methods inherited from interface com.pushtechnology.diffusion.client.session.Feature

Method Detail

putSessionMetricCollector

listSessionMetricCollectors

removeSessionMetricCollector

putTopicMetricCollector

listTopicMetricCollectors

removeTopicMetricCollector

metricsRequest