| 1 | /** |
| 2 | * Copyright (c) Meta Platforms, Inc. and affiliates. |
| 3 | * |
| 4 | * This source code is licensed under the MIT license found in the |
| 5 | * LICENSE file in the root directory of this source tree. |
| 6 | * |
| 7 | * @flow |
| 8 | */ |
| 9 | |
| 10 | import type {PriorityLevel} from '../SchedulerPriorities'; |
| 11 | |
| 12 | declare class TaskController { |
| 13 | constructor(options?: {priority?: string}): TaskController; |
| 14 | signal: mixed; |
| 15 | abort(): void; |
| 16 | } |
| 17 | |
| 18 | type PostTaskPriorityLevel = 'user-blocking' | 'user-visible' | 'background'; |
| 19 | |
| 20 | type CallbackNode = { |
| 21 | _controller: TaskController, |
| 22 | }; |
| 23 | |
| 24 | import { |
| 25 | ImmediatePriority, |
| 26 | UserBlockingPriority, |
| 27 | NormalPriority, |
| 28 | LowPriority, |
| 29 | IdlePriority, |
| 30 | } from '../SchedulerPriorities'; |
| 31 | |
| 32 | export { |
| 33 | ImmediatePriority as unstable_ImmediatePriority, |
| 34 | UserBlockingPriority as unstable_UserBlockingPriority, |
| 35 | NormalPriority as unstable_NormalPriority, |
| 36 | IdlePriority as unstable_IdlePriority, |
| 37 | LowPriority as unstable_LowPriority, |
| 38 | }; |
| 39 | |
| 40 | // Capture local references to native APIs, in case a polyfill overrides them. |
| 41 | const perf = window.performance; |
| 42 | const setTimeout = window.setTimeout; |
| 43 | |
| 44 | // Use experimental Chrome Scheduler postTask API. |
| 45 | const scheduler = global.scheduler; |
| 46 | |
| 47 | const getCurrentTime: () => DOMHighResTimeStamp = perf.now.bind(perf); |
| 48 | |
| 49 | export const unstable_now = getCurrentTime; |
| 50 | |
| 51 | // Scheduler periodically yields in case there is other work on the main |
| 52 | // thread, like user events. By default, it yields multiple times per frame. |
| 53 | // It does not attempt to align with frame boundaries, since most tasks don't |
| 54 | // need to be frame aligned; for those that do, use requestAnimationFrame. |
| 55 | const yieldInterval = 5; |
| 56 | let deadline = 0; |
| 57 | |
| 58 | let currentPriorityLevel_DEPRECATED: PriorityLevel = NormalPriority; |
| 59 | |
| 60 | // Always yield at the end of the frame. |
| 61 | export function unstable_shouldYield(): boolean { |
| 62 | return getCurrentTime() >= deadline; |
| 63 | } |
| 64 | |
| 65 | export function unstable_requestPaint() { |
| 66 | // Since we yield every frame regardless, `requestPaint` has no effect. |
| 67 | } |
| 68 | |
| 69 | type SchedulerCallback<T> = (didTimeout_DEPRECATED: boolean) => |
| 70 | | T |
| 71 | // May return a continuation |
| 72 | | SchedulerCallback<T>; |
| 73 | |
| 74 | export function unstable_scheduleCallback<T>( |
| 75 | priorityLevel: PriorityLevel, |
| 76 | callback: SchedulerCallback<T>, |
| 77 | options?: {delay?: number}, |
| 78 | ): CallbackNode { |
| 79 | let postTaskPriority: PostTaskPriorityLevel; |
| 80 | switch (priorityLevel) { |
| 81 | case ImmediatePriority: |
| 82 | case UserBlockingPriority: |
| 83 | postTaskPriority = 'user-blocking'; |
| 84 | break; |
| 85 | case LowPriority: |
| 86 | case NormalPriority: |
| 87 | postTaskPriority = 'user-visible'; |
| 88 | break; |
| 89 | case IdlePriority: |
| 90 | postTaskPriority = 'background'; |
| 91 | break; |
| 92 | default: |
| 93 | postTaskPriority = 'user-visible'; |
| 94 | break; |
| 95 | } |
| 96 | |
| 97 | const controller = new TaskController({priority: postTaskPriority}); |
| 98 | const postTaskOptions = { |
| 99 | // $FlowFixMe[invalid-compare] |
| 100 | delay: typeof options === 'object' && options !== null ? options.delay : 0, |
| 101 | signal: controller.signal, |
| 102 | }; |
| 103 | |
| 104 | const node = { |
| 105 | _controller: controller, |
| 106 | }; |
| 107 | |
| 108 | scheduler |
| 109 | .postTask( |
| 110 | runTask.bind(null, priorityLevel, postTaskPriority, node, callback), |
| 111 | postTaskOptions, |
| 112 | ) |
| 113 | .catch(handleAbortError); |
| 114 | |
| 115 | return node; |
| 116 | } |
| 117 | |
| 118 | function runTask<T>( |
| 119 | priorityLevel: PriorityLevel, |
| 120 | postTaskPriority: PostTaskPriorityLevel, |
| 121 | node: CallbackNode, |
| 122 | callback: SchedulerCallback<T>, |
| 123 | ) { |
| 124 | deadline = getCurrentTime() + yieldInterval; |
| 125 | try { |
| 126 | currentPriorityLevel_DEPRECATED = priorityLevel; |
| 127 | const didTimeout_DEPRECATED = false; |
| 128 | const result = callback(didTimeout_DEPRECATED); |
| 129 | if (typeof result === 'function') { |
| 130 | // Assume this is a continuation |
| 131 | const continuation: SchedulerCallback<T> = result as any; |
| 132 | const continuationOptions = { |
| 133 | signal: node._controller.signal, |
| 134 | }; |
| 135 | |
| 136 | const nextTask = runTask.bind( |
| 137 | null, |
| 138 | priorityLevel, |
| 139 | postTaskPriority, |
| 140 | node, |
| 141 | continuation, |
| 142 | ); |
| 143 | |
| 144 | if (scheduler.yield !== undefined) { |
| 145 | scheduler |
| 146 | .yield(continuationOptions) |
| 147 | .then(nextTask) |
| 148 | .catch(handleAbortError); |
| 149 | } else { |
| 150 | scheduler |
| 151 | .postTask(nextTask, continuationOptions) |
| 152 | .catch(handleAbortError); |
| 153 | } |
| 154 | } |
| 155 | } catch (error) { |
| 156 | // We're inside a `postTask` promise. If we don't handle this error, then it |
| 157 | // will trigger an "Unhandled promise rejection" error. We don't want that, |
| 158 | // but we do want the default error reporting behavior that normal |
| 159 | // (non-Promise) tasks get for unhandled errors. |
| 160 | // |
| 161 | // So we'll re-throw the error inside a regular browser task. |
| 162 | setTimeout(() => { |
| 163 | throw error; |
| 164 | }); |
| 165 | } finally { |
| 166 | currentPriorityLevel_DEPRECATED = NormalPriority; |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | function handleAbortError(error: any) { |
| 171 | // Abort errors are an implementation detail. We don't expose the |
| 172 | // TaskController to the user, nor do we expose the promise that is returned |
| 173 | // from `postTask`. So we should suppress them, since there's no way for the |
| 174 | // user to handle them. |
| 175 | } |
| 176 | |
| 177 | export function unstable_cancelCallback(node: CallbackNode) { |
| 178 | const controller = node._controller; |
| 179 | controller.abort(); |
| 180 | } |
| 181 | |
| 182 | export function unstable_runWithPriority<T>( |
| 183 | priorityLevel: PriorityLevel, |
| 184 | callback: () => T, |
| 185 | ): T { |
| 186 | const previousPriorityLevel = currentPriorityLevel_DEPRECATED; |
| 187 | currentPriorityLevel_DEPRECATED = priorityLevel; |
| 188 | try { |
| 189 | return callback(); |
| 190 | } finally { |
| 191 | currentPriorityLevel_DEPRECATED = previousPriorityLevel; |
| 192 | } |
| 193 | } |
| 194 | |
| 195 | export function unstable_getCurrentPriorityLevel(): PriorityLevel { |
| 196 | return currentPriorityLevel_DEPRECATED; |
| 197 | } |
| 198 | |
| 199 | export function unstable_next<T>(callback: () => T): T { |
| 200 | let priorityLevel: PriorityLevel; |
| 201 | switch (currentPriorityLevel_DEPRECATED) { |
| 202 | case ImmediatePriority: |
| 203 | case UserBlockingPriority: |
| 204 | case NormalPriority: |
| 205 | // Shift down to normal priority |
| 206 | priorityLevel = NormalPriority; |
| 207 | break; |
| 208 | default: |
| 209 | // Anything lower than normal priority should remain at the current level. |
| 210 | priorityLevel = currentPriorityLevel_DEPRECATED; |
| 211 | break; |
| 212 | } |
| 213 | |
| 214 | const previousPriorityLevel = currentPriorityLevel_DEPRECATED; |
| 215 | currentPriorityLevel_DEPRECATED = priorityLevel; |
| 216 | try { |
| 217 | return callback(); |
| 218 | } finally { |
| 219 | currentPriorityLevel_DEPRECATED = previousPriorityLevel; |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | export function unstable_wrapCallback<T>(callback: () => T): () => T { |
| 224 | const parentPriorityLevel = currentPriorityLevel_DEPRECATED; |
| 225 | return () => { |
| 226 | const previousPriorityLevel = currentPriorityLevel_DEPRECATED; |
| 227 | currentPriorityLevel_DEPRECATED = parentPriorityLevel; |
| 228 | try { |
| 229 | return callback(); |
| 230 | } finally { |
| 231 | currentPriorityLevel_DEPRECATED = previousPriorityLevel; |
| 232 | } |
| 233 | }; |
| 234 | } |
| 235 | |
| 236 | export function unstable_forceFrameRate() {} |
| 237 | |
| 238 | // Currently no profiling build |
| 239 | export const unstable_Profiling = null; |