// Copyright 2018 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.lib.actions;

import com.google.common.base.Joiner;
import java.time.Duration;
import java.util.ArrayList;
import java.util.List;

/** Timing, size, and memory statistics for a Spawn execution. */
public final class SpawnMetrics {
  /** Any non important stats < than 10% will not be shown in the summary. */
  private static final double STATS_SHOW_THRESHOLD = 0.10;

  /** Represents a zero cost/null statistic. */
  public static final SpawnMetrics EMPTY =
      new SpawnMetrics(
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          Duration.ZERO,
          0L,
          0L,
          0L);

  public static SpawnMetrics forLocalExecution(Duration wallTime) {
    return new SpawnMetrics(
        wallTime,
        Duration.ZERO,
        Duration.ZERO,
        Duration.ZERO,
        Duration.ZERO,
        Duration.ZERO,
        Duration.ZERO,
        wallTime,
        Duration.ZERO,
        0L,
        0L,
        0L);
  }

  private final Duration totalTime;
  private final Duration parseTime;
  private final Duration fetchTime;
  private final Duration remoteQueueTime;
  private final Duration uploadTime;
  private final Duration setupTime;
  private final Duration executionWallTime;
  private final Duration retryTime;
  private final Duration networkTime;
  private final long inputBytes;
  private final long inputFiles;
  private final long memoryEstimateBytes;

  public SpawnMetrics(
      Duration totalTime,
      Duration parseTime,
      Duration networkTime,
      Duration fetchTime,
      Duration remoteQueueTime,
      Duration setupTime,
      Duration uploadTime,
      Duration executionWallTime,
      Duration retryTime,
      long inputBytes,
      long inputFiles,
      long memoryEstimateBytes) {
    this.totalTime = totalTime;
    this.parseTime = parseTime;
    this.networkTime = networkTime;
    this.fetchTime = fetchTime;
    this.remoteQueueTime = remoteQueueTime;
    this.setupTime = setupTime;
    this.uploadTime = uploadTime;
    this.executionWallTime = executionWallTime;
    this.retryTime = retryTime;
    this.inputBytes = inputBytes;
    this.inputFiles = inputFiles;
    this.memoryEstimateBytes = memoryEstimateBytes;
  }

  /**
   * Total (measured locally) wall time spent running a spawn. This should be at least as large as
   * all the other times summed together.
   */
  public Duration totalTime() {
    return totalTime;
  }

  /**
   * Total time spent getting on network. This includes time getting network-side errors and the
   * time of the round-trip, found by taking the difference of wall time here and the server time
   * reported by the RPC. This is 0 for locally executed spawns.
   */
  public Duration networkTime() {
    return networkTime;
  }

  /**
   * Total time waiting in remote queues. Includes queue time for any failed attempts. This is 0 for
   * locally executed spawns.
   */
  public Duration remoteQueueTime() {
    return remoteQueueTime;
  }

  /** The time spent transferring files to the backends. This is 0 for locally executed spawns. */
  public Duration uploadTime() {
    return uploadTime;
  }

  /**
   * The time required to setup the environment in which the spawn is run. This may be 0 for locally
   * executed spawns, or may include time to setup a sandbox or other environment. Does not include
   * failed attempts.
   */
  public Duration setupTime() {
    return setupTime;
  }

  /** Time spent running the subprocess. */
  public Duration executionWallTime() {
    return executionWallTime;
  }

  /**
   * The time taken to convert the spawn into a network request, e.g., collecting runfiles, and
   * digests for all input files.
   */
  public Duration parseTime() {
    return parseTime;
  }

  /** Total time spent fetching remote outputs. */
  public Duration fetchTime() {
    return fetchTime;
  }

  /** Time spent in previous failed attempts. Does not include queue time. */
  public Duration retryTime() {
    return retryTime;
  }

  /** Any time that is not measured by a more specific component, out of {@code totalTime()}. */
  public Duration otherTime() {
    return totalTime
        .minus(parseTime)
        .minus(networkTime)
        .minus(remoteQueueTime)
        .minus(uploadTime)
        .minus(setupTime)
        .minus(executionWallTime)
        .minus(fetchTime)
        .minus(retryTime);
  }

  /** Total size in bytes of inputs or 0 if unavailable. */
  public long inputBytes() {
    return inputBytes;
  }

  /** Total number of input files or 0 if unavailable. */
  public long inputFiles() {
    return inputFiles;
  }

  /** Estimated memory usage or 0 if unavailable. */
  public long memoryEstimate() {
    return memoryEstimateBytes;
  }

  /**
   * Generates a String representation of the stats.
   *
   * @param total total time used to compute the percentages
   * @param summary whether to exclude input file count and sizes, and memory estimates
   */
  public String toString(Duration total, boolean summary) {
    StringBuilder sb = new StringBuilder();
    sb.append("(");
    sb.append(prettyPercentage(totalTime, total));
    sb.append(" of the time): [");
    List<String> stats = new ArrayList<>(8);
    addStatToString(stats, "parse", !summary, parseTime, total);
    addStatToString(stats, "queue", true, remoteQueueTime, total);
    addStatToString(stats, "network", !summary, networkTime, total);
    addStatToString(stats, "upload", !summary, uploadTime, total);
    addStatToString(stats, "setup", true, setupTime, total);
    addStatToString(stats, "process", true, executionWallTime, total);
    addStatToString(stats, "fetch", !summary, fetchTime, total);
    addStatToString(stats, "retry", !summary, retryTime, total);
    addStatToString(stats, "other", !summary, otherTime(), total);
    if (!summary) {
      stats.add("input files: " + inputFiles);
      stats.add("input bytes: " + inputBytes);
      stats.add("memory bytes: " + memoryEstimateBytes);
    }
    Joiner.on(", ").appendTo(sb, stats);
    sb.append("]");
    return sb.toString();
  }

  /**
   * Add to {@code strings} the string representation of {@code name} component. If {@code
   * forceShow} is set to false it will only show if it is above certain threshold.
   */
  private static void addStatToString(
      List<String> strings, String name, boolean forceShow, Duration time, Duration totalTime) {
    if (forceShow || isAboveThreshold(time, totalTime)) {
      strings.add(name + ": " + prettyPercentage(time, totalTime));
    }
  }

  private static boolean isAboveThreshold(Duration time, Duration totalTime) {
    return totalTime.toMillis() > 0
        && (((float) time.toMillis() / totalTime.toMillis()) >= STATS_SHOW_THRESHOLD);
  }

  /**
   * Converts relative duration to the percentage string.
   *
   * @return formatted percentage string or "N/A" if result is undefined
   */
  private static String prettyPercentage(Duration duration, Duration total) {
    // Duration.toMillis() != 0 does not imply !Duration.isZero() (due to truncation).
    if (total.toMillis() == 0) {
      // Return "not available" string if total is 0 and result is undefined.
      return "N/A";
    }
    return String.format("%.2f%%", duration.toMillis() * 100.0 / total.toMillis());
  }
}