/*
 * 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.benchmarks.trace;

import static com.google.common.base.Preconditions.checkState;

import io.opencensus.trace.BlankSpan;
import io.opencensus.trace.Span;
import io.opencensus.trace.Tracer;
import io.opencensus.trace.samplers.Samplers;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.TearDown;

/** Benchmarks for {@link io.opencensus.trace.SpanBuilder} and {@link Span}. */
@State(Scope.Benchmark)
public class StartEndSpanBenchmark {
  private static final String SPAN_NAME = "MySpanName";

  @State(Scope.Benchmark)
  public static class Data {
    private Tracer tracer;
    private Span rootSpan = BlankSpan.INSTANCE;

    @Param({"impl", "impl-lite"})
    String implementation;

    @Setup
    public void setup() {
      tracer = BenchmarksUtil.getTracer(implementation);

      rootSpan =
          tracer
              .spanBuilderWithExplicitParent(SPAN_NAME, null)
              .setSampler(Samplers.neverSample())
              .startSpan();
    }

    @TearDown
    public void doTearDown() {
      checkState(rootSpan != BlankSpan.INSTANCE, "Uninitialized rootSpan");
      rootSpan.end();
    }
  }

  /**
   * This benchmark attempts to measure performance of start/end for a non-sampled root {@code
   * Span}.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndNonSampledRootSpan(Data data) {
    Span span =
        data.tracer
            .spanBuilderWithExplicitParent(SPAN_NAME, null)
            .setSampler(Samplers.neverSample())
            .startSpan();
    span.end();
    return span;
  }

  /**
   * This benchmark attempts to measure performance of start/end for a root {@code Span} with record
   * events option.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndRecordEventsRootSpan(Data data) {
    Span span =
        data.tracer
            .spanBuilderWithExplicitParent(SPAN_NAME, null)
            .setSampler(Samplers.neverSample())
            .setRecordEvents(true)
            .startSpan();
    span.end();
    return span;
  }

  /**
   * This benchmark attempts to measure performance of start/end for a sampled root {@code Span}.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndSampledRootSpan(Data data) {
    Span span = data.tracer.spanBuilder(SPAN_NAME).setSampler(Samplers.alwaysSample()).startSpan();
    span.end();
    return span;
  }

  /**
   * This benchmark attempts to measure performance of start/end for a non-sampled child {@code
   * Span}.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndNonSampledChildSpan(Data data) {
    Span span =
        data.tracer
            .spanBuilderWithExplicitParent(SPAN_NAME, data.rootSpan)
            .setSampler(Samplers.neverSample())
            .startSpan();
    span.end();
    return span;
  }

  /**
   * This benchmark attempts to measure performance of start/end for a child {@code Span} with
   * record events option.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndRecordEventsChildSpan(Data data) {
    Span span =
        data.tracer
            .spanBuilderWithExplicitParent(SPAN_NAME, data.rootSpan)
            .setSampler(Samplers.neverSample())
            .setRecordEvents(true)
            .startSpan();
    span.end();
    return span;
  }

  /**
   * This benchmark attempts to measure performance of start/end for a sampled child {@code Span}.
   */
  @Benchmark
  @BenchmarkMode(Mode.SampleTime)
  @OutputTimeUnit(TimeUnit.NANOSECONDS)
  public Span startEndSampledChildSpan(Data data) {
    Span span =
        data.tracer
            .spanBuilderWithExplicitParent(SPAN_NAME, data.rootSpan)
            .setSampler(Samplers.alwaysSample())
            .startSpan();
    span.end();
    return span;
  }
}