Performance metrics: Differentiate requests that are from page load (#24327)

* POC page_load_context header

* refactor to make this.pageLoadContext a private field, and relocate setTimeout code

* add pageLoadContext to `ObserveAPIEndpointDuration` method

* move to telemetry_actions

* move PageContext constant in webapp

* give server control of possible page_load_context values

* variable name change

---------

Co-authored-by: mickmister <mickmister>
Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/web/handlers.go

@@ -407,8 +407,15 @@ func (h Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 		if r.URL.Path != model.APIURLSuffix+"/websocket" {
 			elapsed := float64(time.Since(now)) / float64(time.Second)
+
+			pageLoadContext := r.Header.Get("X-Page-Load-Context")
+			if pageLoadContext != "page_load" && pageLoadContext != "reconnect" {
+				pageLoadContext = ""
+			}
+
 			originClient := string(originClient(r))
-			c.App.Metrics().ObserveAPIEndpointDuration(h.HandlerName, r.Method, statusCode, originClient, elapsed)
+
+			c.App.Metrics().ObserveAPIEndpointDuration(h.HandlerName, r.Method, statusCode, originClient, pageLoadContext, elapsed)
 		}
 	}
 }

server/einterfaces/metrics.go

@@ -58,7 +58,7 @@ type MetricsInterface interface {
 	IncrementFilesSearchCounter()
 	ObserveFilesSearchDuration(elapsed float64)
 	ObserveStoreMethodDuration(method, success string, elapsed float64)
-	ObserveAPIEndpointDuration(endpoint, method, statusCode, originClient string, elapsed float64)
+	ObserveAPIEndpointDuration(endpoint, method, statusCode, originClient, pageLoadContext string, elapsed float64)
 	IncrementPostIndexCounter()
 	IncrementFileIndexCounter()
 	IncrementUserIndexCounter()

server/einterfaces/mocks/MetricsInterface.go

@@ -239,9 +239,9 @@ func (_m *MetricsInterface) IncrementWebsocketReconnectEvent(eventType string) {
 	_m.Called(eventType)
 }
 
-// ObserveAPIEndpointDuration provides a mock function with given fields: endpoint, method, statusCode, originClient, elapsed
+// ObserveAPIEndpointDuration provides a mock function with given fields: endpoint, method, statusCode, originClient, pageLoadContext, elapsed
-func (_m *MetricsInterface) ObserveAPIEndpointDuration(endpoint string, method string, statusCode string, originClient string, elapsed float64) {
+func (_m *MetricsInterface) ObserveAPIEndpointDuration(endpoint string, method string, statusCode string, originClient string, pageLoadContext string, elapsed float64) {
-	_m.Called(endpoint, method, statusCode, originClient, elapsed)
+	_m.Called(endpoint, method, statusCode, originClient, pageLoadContext, elapsed)
 }
 
 // ObserveClusterRequestDuration provides a mock function with given fields: elapsed

webapp/channels/src/actions/telemetry_actions.jsx

@@ -19,6 +19,8 @@ const SUPPORTS_MEASURE_METHODS = isSupported([
     performance.clearMeasures,
 ]);
 
+const HEADER_X_PAGE_LOAD_CONTEXT = 'X-Page-Load-Context';
+
 export function isTelemetryEnabled(state) {
     const config = getConfig(state);
     return config.DiagnosticsEnabled === 'true';
@@ -262,3 +264,16 @@ function updateRequestCountAtMark(name) {
 function getRequestCountAtMark(name) {
     return requestCountAtMark[name] ?? 0;
 }
+
+/**
+ * This allows the server to know that a given HTTP request occurred during page load or reconnect.
+ * The server then uses this information to store metrics fields based on the request context.
+ * The setTimeout approach is a "best effort" approach that will produce false positives.
+ * A more accurate approach will result in more obtrusive code, which would add risk and maintenance cost.
+ */
+export const temporarilySetPageLoadContext = (pageLoadContext) => {
+    Client4.setHeader(HEADER_X_PAGE_LOAD_CONTEXT, pageLoadContext);
+    setTimeout(() => {
+        Client4.removeHeader(HEADER_X_PAGE_LOAD_CONTEXT);
+    }, 5000);
+};

webapp/channels/src/actions/websocket_actions.jsx

@@ -118,9 +118,11 @@ import RemovedFromChannelModal from 'components/removed_from_channel_modal';
 import WebSocketClient from 'client/web_websocket_client';
 import {loadPlugin, loadPluginsIfNecessary, removePlugin} from 'plugins';
 import {getHistory} from 'utils/browser_history';
-import {ActionTypes, Constants, AnnouncementBarMessages, SocketEvents, UserStatuses, ModalIdentifiers, WarnMetricTypes} from 'utils/constants';
+import {ActionTypes, Constants, AnnouncementBarMessages, SocketEvents, UserStatuses, ModalIdentifiers, WarnMetricTypes, PageLoadContext} from 'utils/constants';
 import {getSiteURL} from 'utils/url';
 
+import {temporarilySetPageLoadContext} from './telemetry_actions';
+
 const dispatch = store.dispatch;
 const getState = store.getState;
 
@@ -211,6 +213,8 @@ export function reconnect() {
     // eslint-disable-next-line
     console.log('Reconnecting WebSocket');
 
+    temporarilySetPageLoadContext(PageLoadContext.RECONNECT);
+
     dispatch({
         type: GeneralTypes.WEBSOCKET_SUCCESS,
         timestamp: Date.now(),

webapp/channels/src/components/root/root.tsx

@@ -24,7 +24,7 @@ import type {ActionResult} from 'mattermost-redux/types/actions';
 
 import {loadRecentlyUsedCustomEmojis} from 'actions/emoji_actions';
 import * as GlobalActions from 'actions/global_actions';
-import {measurePageLoadTelemetry, trackEvent, trackSelectorMetrics} from 'actions/telemetry_actions.jsx';
+import {measurePageLoadTelemetry, temporarilySetPageLoadContext, trackEvent, trackSelectorMetrics} from 'actions/telemetry_actions.jsx';
 import BrowserStore from 'stores/browser_store';
 import store from 'stores/redux_store';
 
@@ -53,7 +53,7 @@ import webSocketClient from 'client/web_websocket_client';
 import {initializePlugins} from 'plugins';
 import Pluggable from 'plugins/pluggable';
 import A11yController from 'utils/a11y_controller';
-import {StoragePrefixes} from 'utils/constants';
+import {PageLoadContext, StoragePrefixes} from 'utils/constants';
 import {EmojiIndicesByAlias} from 'utils/emoji';
 import {getSiteURL} from 'utils/url';
 import * as UserAgent from 'utils/user_agent';
@@ -415,6 +415,8 @@ export default class Root extends React.PureComponent<Props, State> {
     };
 
     componentDidMount() {
+        temporarilySetPageLoadContext(PageLoadContext.PAGE_LOAD);
+
         this.mounted = true;
 
         this.initiateMeRequests();

webapp/channels/src/utils/constants.tsx

@@ -2162,4 +2162,9 @@ export const OverActiveUserLimits = {
     MAX: 0.1,
 } as const;
 
+export const PageLoadContext = {
+    PAGE_LOAD: 'page_load',
+    RECONNECT: 'reconnect',
+} as const;
+
 export default Constants;

webapp/platform/client/src/client4.ts

@@ -216,6 +216,14 @@ export default class Client4 {
         this.defaultHeaders['Accept-Language'] = locale;
     }
 
+    setHeader(header: string, value: string) {
+        this.defaultHeaders[header] = value;
+    }
+
+    removeHeader(header: string) {
+        delete this.defaultHeaders[header];
+    }
+
     setEnableLogging(enable: boolean) {
         this.enableLogging = enable;
     }