nl.topicus.jdbc.shaded.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 nl.topicus.jdbc.shaded.io.opencensus.trace;

import nl.topicus.jdbc.shaded.io.grpc.Context;
import nl.topicus.jdbc.shaded.io.opencensus.common.Scope;
import nl.topicus.jdbc.shaded.io.opencensus.trace.unsafe.ContextUtils;

/** Util methods/functionality to interact with the {@link Span} in the {@link nl.topicus.jdbc.shaded.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();
  }

  /**
   * 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.
   * @param endSpan if {@code true} the returned {@code Scope} will close the {@code Span}.
   * @return An object that defines a scope where the given {@code Span} is set to the current
   *     context.
   */
  static Scope withSpan(Span span, boolean endSpan) {
    return new ScopeInSpan(span, endSpan);
  }

  // Defines an arbitrary scope of code as a traceable operation. Supports try-with-resources idiom.
  private static final class ScopeInSpan implements Scope {
    private final Context origContext;
    private final Span span;
    private boolean endSpan;

    /**
     * Constructs a new {@link ScopeInSpan}.
     *
     * @param span is the {@code Span} to be added to the current {@code nl.topicus.jdbc.shaded.io.grpc.Context}.
     */
    ScopeInSpan(Span span, boolean endSpan) {
      this.span = span;
      this.endSpan = endSpan;
      origContext = Context.current().withValue(ContextUtils.CONTEXT_SPAN_KEY, span).attach();
    }

    @Override
    public void close() {
      Context.current().detach(origContext);
      if (endSpan) {
        span.end();
      }
    }
  }
}