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Module containing Observation related code
/*
* Copyright 2022 VMware, 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
*
* https://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.micrometer.observation;
import io.micrometer.common.lang.Nullable;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.function.Supplier;
/**
* Implementations of this interface are responsible for managing state of an
* {@link Observation}.
*
* @author Jonatan Ivanov
* @author Tommy Ludwig
* @author Marcin Grzejszczak
* @since 1.10.0
*/
public interface ObservationRegistry {
/**
* Creates an instance of {@link ObservationRegistry}.
* @return {@link ObservationRegistry} instance
*/
static ObservationRegistry create() {
return new SimpleObservationRegistry();
}
/**
* No-op implementation of {@link ObservationRegistry}.
*/
ObservationRegistry NOOP = new NoopObservationRegistry();
/**
* When previously set will allow to retrieve the {@link Observation} at any point in
* time.
*
* Example: if an {@link Observation} was put in {@link Observation.Scope} then this
* method will return the current present {@link Observation} within the scope.
* @return current observation or {@code null} if it's not present
*/
@Nullable
Observation getCurrentObservation();
/**
* When previously set will allow to retrieve the {@link Observation.Scope} at any
* point in time.
*
* Example: if an {@link Observation} was put in {@link Observation.Scope} then this
* method will return the current present {@link Observation.Scope}.
* @return current observation scope or {@code null} if it's not present
*/
@Nullable
Observation.Scope getCurrentObservationScope();
/**
* Sets the observation scope as current.
* @param current observation scope
*/
void setCurrentObservationScope(@Nullable Observation.Scope current);
/**
* Configuration options for this registry.
* @return observation configuration
*/
ObservationConfig observationConfig();
/**
* Checks whether this {@link ObservationRegistry} is no-op.
* @return {@code true} when this is a no-op observation registry
*/
default boolean isNoop() {
return this == NOOP;
}
/**
* Access to configuration options for this registry.
*/
class ObservationConfig {
private final List> observationHandlers = new CopyOnWriteArrayList<>();
private final List observationPredicates = new CopyOnWriteArrayList<>();
private final List> observationConventions = new CopyOnWriteArrayList<>();
private final List observationFilters = new CopyOnWriteArrayList<>();
/**
* Register a handler for the {@link Observation observations}.
* @param handler handler to add to the current configuration
* @return This configuration instance
*/
public ObservationConfig observationHandler(ObservationHandler handler) {
this.observationHandlers.add(handler);
return this;
}
/**
* Register a predicate to define whether {@link Observation observation} should
* be created or a {@link NoopObservation} instead.
* @param predicate predicate
* @return This configuration instance
*/
public ObservationConfig observationPredicate(ObservationPredicate predicate) {
this.observationPredicates.add(predicate);
return this;
}
/**
* Register an observation filter for the {@link Observation observations}.
* @param observationFilter an observation filter to add to the current
* configuration
* @return This configuration instance
*/
public ObservationConfig observationFilter(ObservationFilter observationFilter) {
this.observationFilters.add(observationFilter);
return this;
}
/**
* Register an {@link ObservationConvention}.
*
* Please check the javadoc of
* {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)}
* method for the logic of choosing the convention.
*
* @param observationConvention observation convention
* @return This configuration instance
*/
public ObservationConfig observationConvention(GlobalObservationConvention observationConvention) {
this.observationConventions.add(observationConvention);
return this;
}
/**
* Finds an {@link ObservationConvention} for the given
* {@link Observation.Context}.
* @param context context
* @param defaultConvention default convention if none found
* @return matching {@link ObservationConvention} or default when no matching
* found
*/
@SuppressWarnings("unchecked")
ObservationConvention getObservationConvention(T context,
ObservationConvention defaultConvention) {
for (ObservationConvention convention : this.observationConventions) {
if (convention.supportsContext(context)) {
return (ObservationConvention) convention;
}
}
return Objects.requireNonNull(defaultConvention, "Default ObservationConvention must not be null");
}
/**
* Check to assert whether {@link Observation} should be created or
* {@link NoopObservation} instead.
* @param name observation technical name
* @param context context
* @return {@code true} when observation is enabled
*/
boolean isObservationEnabled(String name, @Nullable Observation.Context context) {
for (ObservationPredicate predicate : this.observationPredicates) {
if (!predicate.test(name, context)) {
return false;
}
}
return true;
}
// package-private for minimal visibility
Collection> getObservationHandlers() {
return observationHandlers;
}
Collection getObservationFilters() {
return observationFilters;
}
Collection> getObservationConventions() {
return observationConventions;
}
}
}