tubestation/toolkit/components/perfmonitoring/nsIPerformanceStats.idl

/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-*/
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"
#include "nsIArray.idl"
#include "nsIDOMWindow.idl"

/**
 * Mechanisms for querying the current process about performance
 * information.
 *
 * JavaScript clients should rather use PerformanceStats.jsm.
 */

/**
 * Identification details for a performance group.
 *
 * A performance group is a set of JavaScript compartments whose
 * performance is observed as a single entity. Typical examples of
 * performance groups: a webpage without its frames, a
 * webpage with all its frames, the entire JS runtime, ...
 */
[scriptable, builtinclass, uuid(994c56be-939a-4f20-8364-124f6422d86a)]
interface nsIPerformanceGroupDetails: nsISupports {
  /**
   * An identifier unique to the component.
   *
   * This identifier is somewhat human-readable to aid with debugging,
   * but clients should not rely upon the format.
   */
  readonly attribute AString groupId;

  /**
   * A somewhat human-readable name for the component.
   */
  readonly attribute AString name;

  /**
   * If the component is code executed in a window, the ID of the topmost
   * outer window (i.e. the tab), otherwise 0.
   */
  readonly attribute uint64_t windowId;

  /**
   * `true` if this component is executed with system privileges
   * (e.g. the platform itself), `false` otherwise
   * (e.g. webpages).
   */
  readonly attribute bool isSystem;

  /**
   * The process running this group.
   */
  readonly attribute unsigned long long processId;

  /**
   * `true` if the code is executed in a content process, `false` otherwise.
   */
  readonly attribute bool isContentProcess;
};

/**
 * Snapshot of the performance of a component, e.g. a web
 * page, system built-ins, a module or the entire process itself.
 *
 * All values are monotonic and are updated only when
 * `nsIPerformanceStatsService.isStopwatchActive` is `true`.
 */
[scriptable, builtinclass, uuid(8a635d4b-aa56-466b-9a7d-9f91ca9405ef)]
interface nsIPerformanceStats: nsIPerformanceGroupDetails {
  /**
   * Total amount of time spent executing code in this group, in
   * microseconds.
   */
  readonly attribute unsigned long long totalUserTime;
  readonly attribute unsigned long long totalSystemTime;
  readonly attribute unsigned long long totalCPOWTime;

  /**
   * Total number of times code execution entered this group,
   * since process launch. This may be greater than the number
   * of times we have entered the event loop.
   */
  readonly attribute unsigned long long ticks;

  /**
   * Jank indicator.
   *
   * durations[i] == number of times execution of this group
   * lasted at lest 2^i ms.
   */
  void getDurations([optional] out unsigned long aCount,
                    [retval, array, size_is(aCount)]out unsigned long long aNumberOfOccurrences);
};

/**
 * A snapshot of the performance data of the process.
 */
[scriptable, builtinclass, uuid(13cc235b-739e-4690-b0e3-d89cbe036a93)]
interface nsIPerformanceSnapshot: nsISupports {
  /**
   * Data on all individual components.
   */
  nsIArray getComponentsData();

  /**
   * Information on the process itself.
   *
   * This contains the total amount of time spent executing JS code,
   * the total amount of time spent waiting for system calls while
   * executing JS code, the total amount of time performing blocking
   * inter-process calls, etc.
   */
  nsIPerformanceStats getProcessData();
};

/**
 * A performance alert.
 */
[scriptable, builtinclass, uuid(a85706ab-d703-4687-8865-78cd771eab93)]
interface nsIPerformanceAlert: nsISupports {
 /**
  * A slowdown was detected.
  *
  * See REASON_JANK_* for details on whether this slowdown was user-noticeable.
  */
  const unsigned long REASON_SLOWDOWN = 1;

  /**
   * This alert was triggered during a jank in animation.
   *
   * In the current implementation, we consider that there is a jank
   * in animation if delivery of the vsync message to the main thread
   * has been delayed too much (see
   * nsIPerformanceStatsService.animationJankLevelThreshold).
   *
   * Note that this is a heuristic which may provide false positives,
   * so clients of this API are expected to perform post-processing to
   * filter out such false positives.
   */
  const unsigned long REASON_JANK_IN_ANIMATION = 2;

  /**
   * This alert was triggered during a jank in user input.
   *
   * In the current implementation, we consider that there is a jank
   * in animation if a user input was received either immediately
   * before executing the offending code (see
   * nsIPerformanceStatsService.userInputDelayThreshold) or while
   * executing the offending code.
   *
   * Note that this is a heuristic which may provide false positives,
   * so clients of this API are expected to perform post-processing to
   * filter out such false positives.
   */
  const unsigned long REASON_JANK_IN_INPUT = 4;

  /**
   * The reason for the alert, as a bitwise or of the various REASON_*
   * constants.
   */
  readonly attribute unsigned long reason;

  /**
   * Longest interval spent executing code in this group
   * since the latest alert, in microseconds.
   *
   * Note that the underlying algorithm is probabilistic and may
   * provide false positives, so clients of this API are expected to
   * perform post-processing to filter out such false positives. In
   * particular, a high system load will increase the noise level on
   * this measure.
   */
  readonly attribute unsigned long long highestJank;

  /**
   * Longest interval spent executing CPOW in this group
   * since the latest alert, in microseconds.
   *
   * This measure is reliable and involves no heuristics. However,
   * note that the duration of CPOWs is increased by high system
   * loads.
   */
  readonly attribute unsigned long long highestCPOW;
};


/**
 * An observer for slow performance alerts.
 */
[scriptable, function, uuid(b746a929-3fec-420b-8ed8-c35d71995e05)]
interface nsIPerformanceObserver: nsISupports {
  /**
   * @param target The performance group that caused the jank.
   * @param alert The performance cost that triggered the alert.
   */
  void observe(in nsIPerformanceGroupDetails target, in nsIPerformanceAlert alert);
};


/**
 * A part of the system that may be observed for slow performance.
 */
[scriptable, builtinclass, uuid(b85720d0-e328-4342-9e46-8ca1acf8c70e)]
interface nsIPerformanceObservable: nsISupports {
  /**
   * If a single group is being observed, information on this group.
   */
  readonly attribute nsIPerformanceGroupDetails target;

  /**
   * Add an observer that will be informed in case of jank.
   *
   * Set `jankAlertThreshold` to determine how much jank is needed
   * to trigger alerts.
   *
   * If the same observer is added more than once, it will be
   * triggered as many times as it has been added.
   */
  void addJankObserver(in nsIPerformanceObserver observer);

  /**
   * Remove an observer previously added with `addJankObserver`.
   *
   * Noop if the observer hasn't been added.
   */
  void removeJankObserver(in nsIPerformanceObserver observer);
};


[scriptable, uuid(505bc42e-be38-4a53-baba-92cb33690cde)]
interface nsIPerformanceStatsService : nsISupports {
  /**
   * `true` if we should monitor CPOW, `false` otherwise.
   */
  [implicit_jscontext] attribute bool isMonitoringCPOW;

  /**
   * `true` if we should monitor jank, `false` otherwise.
   */
  [implicit_jscontext] attribute bool isMonitoringJank;

  /**
   * `true` if all compartments need to be monitored individually,
   * `false` if only performance groups (i.e. entire webpages, etc.)
   * need to be monitored.
   */
  [implicit_jscontext] attribute bool isMonitoringPerCompartment;

  /**
   * Capture a snapshot of the performance data.
   */
  [implicit_jscontext] nsIPerformanceSnapshot getSnapshot();

  /**
   * The threshold, in microseconds, above which a performance group is
   * considered "slow" and should raise performance alerts.
   */
  attribute unsigned long long jankAlertThreshold;

  /**
   * If a user is seeing an animation and we spend too long executing
   * JS code while blocking refresh, this will be visible to the user.
   *
   * We assume that any jank during an animation and lasting more than
   * 2^animationJankLevelThreshold ms will be visible.
   */
  attribute short animationJankLevelThreshold;

  /**
   * If a user performs an input (e.g. clicking, pressing a key, but
   * *NOT* moving the mouse), and we spend too long executing JS code
   * before displaying feedback, this will be visible to the user even
   * if there is no ongoing animation.
   *
   * We assume that any jank during `userInputDelayThreshold` us after
   * the user input will be visible.
   */
  attribute unsigned long long userInputDelayThreshold;

  /**
   * A buffering delay, in milliseconds, used by the service to
   * regroup performance alerts, before observers are actually
   * noticed. Higher delays let the system avoid redundant
   * notifications for the same group, and are generally better for
   * performance.
   */
  attribute unsigned long jankAlertBufferingDelay;

  /**
   * Get a nsIPerformanceObservable representing a DOM window. This
   * observable may then be used to (un)register for watching
   * performance alerts for this window.
   *
   * Note that this covers only the current process.
   *
   * Use special window id 0 to get an observable that may be used to
   * (un)register for watching performance alerts of all windows at
   * once.
   */
  nsIPerformanceObservable getObservableWindow(in unsigned long long windowId);
};


%{C++
#define NS_TOOLKIT_PERFORMANCESTATSSERVICE_CID {0xfd7435d4, 0x9ec4, 0x4699, \
      {0xad, 0xd4, 0x1b, 0xe8, 0x3d, 0xd6, 0x8e, 0xf3} }
#define NS_TOOLKIT_PERFORMANCESTATSSERVICE_CONTRACTID "@mozilla.org/toolkit/performance-stats-service;1"
%}