io.opencensus.trace.unsafe.ContextUtils 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.unsafe;
import io.grpc.Context;
import io.opencensus.internal.Utils;
import io.opencensus.trace.BlankSpan;
import io.opencensus.trace.Span;
/*>>>
import org.checkerframework.checker.nullness.qual.Nullable;
*/
/**
* Util methods/functionality to interact with the {@link io.grpc.Context}.
*
* Users must interact with the current Context via the public APIs in {@link
* io.opencensus.trace.Tracer} and avoid usages of the {@link #CONTEXT_SPAN_KEY} directly.
*
* @since 0.5
*/
public final class ContextUtils {
// No instance of this class.
private ContextUtils() {}
/** The {@link io.grpc.Context.Key} used to interact with {@link io.grpc.Context}. */
private static final Context.Key CONTEXT_SPAN_KEY =
Context.key("opencensus-trace-span-key");
/**
* Creates a new {@code Context} with the given value set.
*
* @param context the parent {@code Context}.
* @param span the value to be set.
* @return a new context with the given value set.
* @since 0.21
*/
public static Context withValue(Context context, @javax.annotation.Nullable Span span) {
return Utils.checkNotNull(context, "context").withValue(CONTEXT_SPAN_KEY, span);
}
/**
* Returns the value from the specified {@code Context}.
*
* @param context the specified {@code Context}.
* @return the value from the specified {@code Context}.
* @since 0.21
*/
public static Span getValue(Context context) {
@javax.annotation.Nullable
Span span = CONTEXT_SPAN_KEY.get(Utils.checkNotNull(context, "context"));
return span == null ? BlankSpan.INSTANCE : span;
}
}