11import type { TurbopackMessageAction } from '../../../../server/dev/hot-reloader-types'
22import type { Update as TurbopackUpdate } from '../../../../build/swc/types'
33
4+ declare global {
5+ interface Window {
6+ __NEXT_HMR_TURBOPACK_REPORT_NOISY_NOOP_EVENTS : boolean | undefined
7+ }
8+ }
9+
10+ // How long to wait before reporting the HMR start, used to suppress irrelevant
11+ // `BUILDING` events. Does not impact reported latency.
12+ const TURBOPACK_HMR_START_DELAY_MS = 100
13+
414interface HmrUpdate {
15+ hasUpdates : boolean
516 updatedModules : Set < string >
617 startMsSinceEpoch : number
718 endMsSinceEpoch : number
@@ -11,36 +22,97 @@ export class TurbopackHmr {
1122 #updatedModules: Set < string >
1223 #startMsSinceEpoch: number | undefined
1324 #lastUpdateMsSinceEpoch: number | undefined
25+ #deferredReportHmrStartId: ReturnType < typeof setTimeout > | undefined
1426
1527 constructor ( ) {
1628 this . #updatedModules = new Set ( )
1729 }
1830
31+ // HACK: Turbopack tends to generate a lot of irrelevant "BUILDING" actions,
32+ // as it reports *any* compilation, including fully no-op/cached compilations
33+ // and those unrelated to HMR. Fixing this would require significant
34+ // architectural changes.
35+ //
36+ // Work around this by deferring any "rebuilding" message by 100ms. If we get
37+ // a BUILT event within that threshold and nothing has changed, just suppress
38+ // the message entirely.
39+ #runDeferredReportHmrStart( ) {
40+ if ( this . #deferredReportHmrStartId != null ) {
41+ console . log ( '[Fast Refresh] rebuilding' )
42+ this . #cancelDeferredReportHmrStart( )
43+ }
44+ }
45+
46+ #cancelDeferredReportHmrStart( ) {
47+ clearTimeout ( this . #deferredReportHmrStartId)
48+ this . #deferredReportHmrStartId = undefined
49+ }
50+
1951 onBuilding ( ) {
2052 this . #lastUpdateMsSinceEpoch = undefined
53+ this . #cancelDeferredReportHmrStart( )
2154 this . #startMsSinceEpoch = Date . now ( )
55+
56+ // report the HMR start after a short delay
57+ this . #deferredReportHmrStartId = setTimeout (
58+ ( ) => this . #runDeferredReportHmrStart( ) ,
59+ // debugging feature: don't defer/suppress noisy no-op HMR update messages
60+ self . __NEXT_HMR_TURBOPACK_REPORT_NOISY_NOOP_EVENTS
61+ ? 0
62+ : TURBOPACK_HMR_START_DELAY_MS
63+ )
2264 }
2365
24- onTurbopackMessage ( msg : TurbopackMessageAction ) {
66+ /** Helper for other `onEvent` methods. */
67+ #onUpdate( ) {
68+ this . #runDeferredReportHmrStart( )
2569 this . #lastUpdateMsSinceEpoch = Date . now ( )
70+ }
71+
72+ onTurbopackMessage ( msg : TurbopackMessageAction ) {
73+ this . #onUpdate( )
2674 const updatedModules = extractModulesFromTurbopackMessage ( msg . data )
2775 for ( const module of updatedModules ) {
2876 this . #updatedModules. add ( module )
2977 }
3078 }
3179
80+ onServerComponentChanges ( ) {
81+ this . #onUpdate( )
82+ }
83+
84+ onReloadPage ( ) {
85+ this . #onUpdate( )
86+ }
87+
88+ onPageAddRemove ( ) {
89+ this . #onUpdate( )
90+ }
91+
92+ /**
93+ * @returns `null` if the caller should ignore the update entirely. Returns an
94+ * object with `hasUpdates: false` if the caller should report the end of
95+ * the HMR in the browser console, but the HMR was a no-op.
96+ */
3297 onBuilt ( ) : HmrUpdate | null {
33- // it's possible for `this.#startMsSinceEpoch` to not be set if this was the initial
34- // computation, just return null in this case.
35- if ( this . #startMsSinceEpoch == null ) {
98+ // Check that we got *any* `TurbopackMessageAction`, even if
99+ // `updatedModules` is empty (not everything gets recorded there).
100+ //
101+ // There's also a case where `onBuilt` gets called before `onBuilding`,
102+ // which can happen during initial page load. Ignore that too!
103+ const hasUpdates =
104+ this . #lastUpdateMsSinceEpoch != null && this . #startMsSinceEpoch != null
105+ if ( ! hasUpdates && this . #deferredReportHmrStartId != null ) {
106+ // suppress the update entirely
107+ this . #cancelDeferredReportHmrStart( )
36108 return null
37109 }
110+ this . #runDeferredReportHmrStart( )
111+
38112 const result = {
113+ hasUpdates,
39114 updatedModules : this . #updatedModules,
40115 startMsSinceEpoch : this . #startMsSinceEpoch! ,
41- // Turbopack has a debounce which causes every BUILT message to appear
42- // 30ms late. We don't want to include this latency in our reporting, so
43- // prefer to use the last TURBOPACK_MESSAGE time.
44116 endMsSinceEpoch : this . #lastUpdateMsSinceEpoch ?? Date . now ( ) ,
45117 }
46118 this . #updatedModules = new Set ( )
0 commit comments