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/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
/* vim: set sts=2 sw=2 et 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/. */
// Map of the base histogram ids for the metrics recorded for the extensions.
const histograms = {
extensionStartup: "WEBEXT_EXTENSION_STARTUP_MS",
backgroundPageLoad: "WEBEXT_BACKGROUND_PAGE_LOAD_MS",
browserActionPopupOpen: "WEBEXT_BROWSERACTION_POPUP_OPEN_MS",
browserActionPreloadResult: "WEBEXT_BROWSERACTION_POPUP_PRELOAD_RESULT_COUNT",
contentScriptInjection: "WEBEXT_CONTENT_SCRIPT_INJECTION_MS",
eventPageRunningTime: "WEBEXT_EVENTPAGE_RUNNING_TIME_MS",
eventPageIdleResult: "WEBEXT_EVENTPAGE_IDLE_RESULT_COUNT",
pageActionPopupOpen: "WEBEXT_PAGEACTION_POPUP_OPEN_MS",
storageLocalGetJSON: "WEBEXT_STORAGE_LOCAL_GET_MS",
storageLocalSetJSON: "WEBEXT_STORAGE_LOCAL_SET_MS",
storageLocalGetIDB: "WEBEXT_STORAGE_LOCAL_IDB_GET_MS",
storageLocalSetIDB: "WEBEXT_STORAGE_LOCAL_IDB_SET_MS",
};
/**
* Get a trimmed version of the given string if it is longer than 80 chars (used in telemetry
* when a string may be longer than allowed).
*
* @param {string} str
* The original string content.
*
* @returns {string}
* The trimmed version of the string when longer than 80 chars, or the given string
* unmodified otherwise.
*/
export function getTrimmedString(str) {
if (str.length <= 80) {
return str;
}
const length = str.length;
// Trim the string to prevent a flood of warnings messages logged internally by recordEvent,
// the trimmed version is going to be composed by the first 40 chars and the last 37 and 3 dots
// that joins the two parts, to visually indicate that the string has been trimmed.
return `${str.slice(0, 40)}...${str.slice(length - 37, length)}`;
}
/**
* Get a string representing the error which can be included in telemetry data.
* If the resulting string is longer than 80 characters it is going to be
* trimmed using the `getTrimmedString` helper function.
*
* @param {Error | DOMException | Components.Exception} error
* The error object to convert into a string representation.
*
* @returns {string}
* - The `error.name` string on DOMException or Components.Exception
* (trimmed to 80 chars).
* - "NoError" if error is falsey.
* - "UnkownError" as a fallback.
*/
export function getErrorNameForTelemetry(error) {
let text = "UnknownError";
if (!error) {
text = "NoError";
} else if (
DOMException.isInstance(error) ||
error instanceof Components.Exception
) {
text = error.name;
if (text.length > 80) {
text = getTrimmedString(text);
}
}
return text;
}
/**
* This is a internal helper object which contains a collection of helpers used to make it easier
* to collect extension telemetry (in both the general histogram and in the one keyed by addon id).
*
* This helper object is not exported from ExtensionUtils, it is used by the ExtensionTelemetry
* Proxy which is exported and used by the callers to record telemetry data for one of the
* supported metrics.
*/
class ExtensionTelemetryMetric {
constructor(metric) {
this.metric = metric;
}
// Stopwatch methods.
stopwatchStart(extension, obj = extension) {
this._wrappedStopwatchMethod("start", this.metric, extension, obj);
}
stopwatchFinish(extension, obj = extension) {
this._wrappedStopwatchMethod("finish", this.metric, extension, obj);
}
stopwatchCancel(extension, obj = extension) {
this._wrappedStopwatchMethod("cancel", this.metric, extension, obj);
}
// Histogram counters methods.
histogramAdd(opts) {
this._histogramAdd(this.metric, opts);
}
/**
* Wraps a call to a TelemetryStopwatch method for a given metric and extension.
*
* @param {string} method
* The stopwatch method to call ("start", "finish" or "cancel").
* @param {string} metric
* The stopwatch metric to record (used to retrieve the base histogram id from the _histogram object).
* @param {Extension | BrowserExtensionContent} extension
* The extension to record the telemetry for.
* @param {any | undefined} [obj = extension]
* An optional telemetry stopwatch object (which defaults to the extension parameter when missing).
*/
_wrappedStopwatchMethod(method, metric, extension, obj = extension) {
if (!extension) {
throw new Error(`Mandatory extension parameter is undefined`);
}
const baseId = histograms[metric];
if (!baseId) {
throw new Error(`Unknown metric ${metric}`);
}
// Record metric in the general histogram.
TelemetryStopwatch[method](baseId, obj);
// Record metric in the histogram keyed by addon id.
let extensionId = getTrimmedString(extension.id);
TelemetryStopwatch[`${method}Keyed`](
`${baseId}_BY_ADDONID`,
extensionId,
obj
);
}
/**
* Record a telemetry category and/or value for a given metric.
*
* @param {string} metric
* The metric to record (used to retrieve the base histogram id from the _histogram object).
* @param {object} options
* @param {Extension | BrowserExtensionContent} options.extension
* The extension to record the telemetry for.
* @param {string | undefined} [options.category]
* An optional histogram category.
* @param {number | undefined} [options.value]
* An optional value to record.
*/
_histogramAdd(metric, { category, extension, value }) {
if (!extension) {
throw new Error(`Mandatory extension parameter is undefined`);
}
const baseId = histograms[metric];
if (!baseId) {
throw new Error(`Unknown metric ${metric}`);
}
const histogram = Services.telemetry.getHistogramById(baseId);
if (typeof category === "string") {
histogram.add(category, value);
} else {
histogram.add(value);
}
const keyedHistogram = Services.telemetry.getKeyedHistogramById(
`${baseId}_BY_ADDONID`
);
const extensionId = getTrimmedString(extension.id);
if (typeof category === "string") {
keyedHistogram.add(extensionId, category, value);
} else {
keyedHistogram.add(extensionId, value);
}
}
}
// Cache of the ExtensionTelemetryMetric instances that has been lazily created by the
// Extension Telemetry Proxy.
const metricsCache = new Map();
/**
* This proxy object provides the telemetry helpers for the currently supported metrics (the ones listed in
* ExtensionTelemetryHelpers._histograms), the telemetry helpers for a particular metric are lazily created
* when the related property is being accessed on this object for the first time, e.g.:
*
* ExtensionTelemetry.extensionStartup.stopwatchStart(extension);
* ExtensionTelemetry.browserActionPreloadResult.histogramAdd({category: "Shown", extension});
*/
export var ExtensionTelemetry = new Proxy(metricsCache, {
get(target, prop, receiver) {
if (!(prop in histograms)) {
throw new Error(`Unknown metric ${prop}`);
}
// Lazily create and cache the metric result object.
if (!target.has(prop)) {
target.set(prop, new ExtensionTelemetryMetric(prop));
}
return target.get(prop);
},
});
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