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/* 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/. */
"use strict";
/**
* This function returns a middleware, which is responsible for adding markers that will
* be visible in performance profiles, and may help investigate performance issues.
*
* Example usage, adding a marker when console messages are added, and when they are cleared:
*
* return createPerformanceMarkerMiddleware({
* "MESSAGES_ADD": {
* label: "WebconsoleAddMessages",
* sessionId: 12345,
* getMarkerDescription: function({ action, state }) {
* const { messages } = action;
* const totalMessageCount = state.messages.mutableMessagesById.size;
* return `${messages.length} messages handled, store now has ${totalMessageCount} messages`;
* },
* },
* "MESSAGES_CLEARED": {
* label: "WebconsoleClearMessages",
* sessionId: 12345
* },
* });
*
* @param {Object} cases: An object, keyed by action type, that will determine if a
* given action will add a marker.
* @param {String} cases.{actionType} - The type of the action that will trigger the
* marker creation.
* @param {String} cases.{actionType}.label - The marker label
* @param {Integer} cases.{actionType}.sessionId - The telemetry sessionId. This is used
* to be able to distinguish markers coming from different toolboxes.
* @param {Function} [cases.{actionType}.getMarkerDescription] - An optional function that
* will be called when adding the marker to populate its description. The function
* is called with an object holding the action and the state
*/
function createPerformanceMarkerMiddleware(cases) {
return function (store) {
return next => action => {
const condition = cases[action.type];
const shouldAddProfileMarker = !!condition;
// Start the marker timer before calling next(action).
const startTime = shouldAddProfileMarker ? Cu.now() : null;
const newState = next(action);
if (shouldAddProfileMarker) {
ChromeUtils.addProfilerMarker(
`${condition.label} ${condition.sessionId}`,
startTime,
condition.getMarkerDescription
? condition.getMarkerDescription({
action,
state: store.getState(),
})
: ""
);
}
return newState;
};
};
}
module.exports = {
createPerformanceMarkerMiddleware,
};
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