forked from mirrors/gecko-dev
71 lines
2.6 KiB
JavaScript
71 lines
2.6 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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const ChromeUtils = require("ChromeUtils");
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const { Cu } = require("chrome");
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/**
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* This function returns a middleware, which is responsible for adding markers that will
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* be visible in performance profiles, and may help investigate performance issues.
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*
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* Example usage, adding a marker when console messages are added, and when they are cleared:
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*
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* return createPerformanceMarkerMiddleware({
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* "MESSAGES_ADD": {
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* label: "WebconsoleAddMessages",
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* sessionId: 12345,
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* getMarkerDescription: function({ action, state }) {
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* const { messages } = action;
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* const totalMessageCount = state.messages.messagesById.size;
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* return `${messages.length} messages handled, store now has ${totalMessageCount} messages`;
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* },
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* },
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* "MESSAGES_CLEARED": {
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* label: "WebconsoleClearMessages",
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* sessionId: 12345
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* },
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* });
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*
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* @param {Object} cases: An object, keyed by action type, that will determine if a
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* given action will add a marker.
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* @param {String} cases.{actionType} - The type of the action that will trigger the
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* marker creation.
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* @param {String} cases.{actionType}.label - The marker label
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* @param {Integer} cases.{actionType}.sessionId - The telemetry sessionId. This is used
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* to be able to distinguish markers coming from different toolboxes.
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* @param {Function} [cases.{actionType}.getMarkerDescription] - An optional function that
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* will be called when adding the marker to populate its description. The function
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* is called with an object holding the action and the state
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*/
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function createPerformanceMarkerMiddleware(cases) {
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return function(store) {
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return next => action => {
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const condition = cases[action.type];
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const shouldAddProfileMarker = !!condition;
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// Start the marker timer before calling next(action).
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const startTime = shouldAddProfileMarker ? Cu.now() : null;
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const newState = next(action);
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if (shouldAddProfileMarker) {
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ChromeUtils.addProfilerMarker(
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`${condition.label} ${condition.sessionId}`,
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startTime,
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condition.getMarkerDescription
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? condition.getMarkerDescription({
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action,
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state: store.getState(),
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})
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: ""
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);
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}
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return newState;
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};
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};
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}
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module.exports = {
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createPerformanceMarkerMiddleware,
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};
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