org.springframework.cloud.sleuth.SamplerFunction Maven / Gradle / Ivy
/*
* Copyright 2013-2021 the original author or authors.
*
* 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 org.springframework.cloud.sleuth;
import org.springframework.lang.Nullable;
/**
* This API was heavily influenced by Brave. Parts of its documentation were taken
* directly from Brave.
*
* Decides whether to start a new trace based on request properties such as an HTTP path.
*
* @param type of the input, for example a request or method
* @author OpenZipkin Brave Authors
* @author Marcin Grzejszczak
* @since 3.0.0
*/
public interface SamplerFunction {
/**
* Returns an overriding sampling decision for a new trace.
* @param arg parameter to evaluate for a sampling decision. {@code null} input
* results in a {@code null} result
* @return {@code true} to sample a new trace or {@code false} to deny. {@code null}
* defers the decision.
*/
@Nullable
Boolean trySample(@Nullable T arg);
/**
* Always deferring {@link SamplerFunction}.
* @param type of the input, for example a request or method
* @return decision deferring sampler function
*/
static SamplerFunction deferDecision() {
return (SamplerFunction) Constants.DEFER_DECISION;
}
/**
* Never sampling {@link SamplerFunction}.
* @param type of the input, for example a request or method
* @return never sampling sampler function
*/
static SamplerFunction neverSample() {
return (SamplerFunction) Constants.NEVER_SAMPLE;
}
/**
* Always sampling {@link SamplerFunction}.
* @param type of the input, for example a request or method
* @return always sampling sampler function
*/
static SamplerFunction alwaysSample() {
return (SamplerFunction) Constants.ALWAYS_SAMPLE;
}
/**
* Constant {@link SamplerFunction}s.
*/
enum Constants implements SamplerFunction