io.opencensus.trace.CurrentSpanUtils Maven / Gradle / Ivy
/*
* Copyright 2017, OpenCensus 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
*
* 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.opencensus.trace;
import io.grpc.Context;
import io.opencensus.common.Scope;
import io.opencensus.trace.unsafe.ContextUtils;
/**
* Util methods/functionality to interact with the {@link Span} in the {@link io.grpc.Context}.
*/
final class CurrentSpanUtils {
// No instance of this class.
private CurrentSpanUtils() {}
/**
* Returns The {@link Span} from the current context.
*
* @return The {@code Span} from the current context.
*/
static Span getCurrentSpan() {
return ContextUtils.CONTEXT_SPAN_KEY.get(Context.current());
}
/**
* Enters the scope of code where the given {@link Span} is in the current context, and returns an
* object that represents that scope. The scope is exited when the returned object is closed.
*
* Supports try-with-resource idiom.
*
* @param span The {@code Span} to be set to the current context.
* @return An object that defines a scope where the given {@code Span} is set to the current
* context.
*/
static Scope withSpan(Span span) {
return new WithSpan(span, ContextUtils.CONTEXT_SPAN_KEY);
}
// Defines an arbitrary scope of code as a traceable operation. Supports try-with-resources idiom.
private static final class WithSpan implements Scope {
private final Context origContext;
/**
* Constructs a new {@link WithSpan}.
*
* @param span is the {@code Span} to be added to the current {@code io.grpc.Context}.
* @param contextKey is the {@code Context.Key} used to set/get {@code Span} from the {@code
* Context}.
*/
WithSpan(Span span, Context.Key contextKey) {
origContext = Context.current().withValue(contextKey, span).attach();
}
@Override
public void close() {
Context.current().detach(origContext);
}
}
}