⚡ perf(vscode): 切走的预览文件改了不在后台生成文档，切回来再补一次

vscode/src/codeReader/editor/previewEditor.test.ts

@@ -253,6 +253,13 @@ function tab() {
   }
 }
 
+/** 别处改了这份文件，文档变成 version 版：交给最近打开的预览听着的那个回调 */
+function edit(document: { version: number }, version: number): void {
+  document.version = version
+  const changed = vi.mocked(workspace.onDidChangeTextDocument).mock.calls.at(-1)![0]
+  changed({ document, contentChanges: [{ rangeOffset: 0, rangeLength: 0, text: '// ' }] } as never)
+}
+
 const comparedWithHead = expect.objectContaining({ type: 'diff', diff: expect.objectContaining({ base: '上一次提交' }) })
 
 describe('预览对比什么看这个标签页是从哪儿打开的', () => {
@@ -365,7 +372,7 @@ describe('标签页切走时页面留着', () => {
     expect(commands.executeCommand).not.toHaveBeenCalledWith('setContext', OCCURRENCES_CONTEXT, false)
   })
 
-  it('切走期间文件在别处改了：照常把新的文档发给留着的页面', async () => {
+  it('切走期间文件在别处改了：不生成、不发文档，切回来生成一次发出去', async () => {
     const { provider, document } = opening()
     const page = tab()
     provider.resolveCustomTextEditor(document as never, page.panel)
@@ -373,9 +380,65 @@ describe('标签页切走时页面留着', () => {
 
     page.hide()
     page.clear()
-    document.version = 2
-    const edited = vi.mocked(workspace.onDidChangeTextDocument).mock.calls.at(-1)![0]
-    edited({ document, contentChanges: [{ rangeOffset: 0, rangeLength: 0, text: '// ' }] } as never)
+    vi.mocked(documentMessage).mockClear()
+    edit(document, 2)
+    edit(document, 3)
+    await new Promise(resolve => setTimeout(resolve, 200))
+    expect(documentMessage).not.toHaveBeenCalled()
+    expect(page.posted()).toEqual([])
+
+    page.show()
+    await vi.waitFor(() => expect(page.posted()).toContainEqual(expect.objectContaining({ type: 'document', version: 3 })))
+    expect(documentMessage).toHaveBeenCalledTimes(1)
+  })
+
+  it('改完还没来得及生成就切走了：排着的那次不在后台跑，切回来再生成', async () => {
+    const { provider, document } = opening()
+    const page = tab()
+    provider.resolveCustomTextEditor(document as never, page.panel)
+    await page.send({ type: 'ready' })
+
+    page.clear()
+    vi.mocked(documentMessage).mockClear()
+    edit(document, 2)
+    page.hide()
+    await new Promise(resolve => setTimeout(resolve, 200))
+    expect(documentMessage).not.toHaveBeenCalled()
+
+    page.show()
+    await vi.waitFor(() => expect(page.posted()).toContainEqual(expect.objectContaining({ type: 'document', version: 2 })))
+    expect(documentMessage).toHaveBeenCalledTimes(1)
+  })
+
+  it('切回来时还要滚到别处（跳定义打到它）：等补发的文档一起带过去，不先滚旧的', async () => {
+    const { provider, document } = opening()
+    const page = tab()
+    provider.resolveCustomTextEditor(document as never, page.panel)
+    await page.send({ type: 'ready' })
+
+    page.hide()
+    edit(document, 2)
+    await new Promise(resolve => setTimeout(resolve, 200))
+    page.clear()
+    // 补生成要一会儿：跳过来的位置在生成完之前就到了
+    const generate = vi.mocked(documentMessage).getMockImplementation()!
+    vi.mocked(documentMessage).mockImplementationOnce(async (...args) => {
+      await new Promise(resolve => setTimeout(resolve, 50))
+      return generate(...args)
+    })
+    await provider.open(document.uri as never, { reveal: { line: 1 } }, async () => page.show())
+    await vi.waitFor(() => expect(page.posted()).toContainEqual(expect.objectContaining({ type: 'document', version: 2, reveal: { line: 1 } })))
+    expect(page.posted()).not.toContainEqual(expect.objectContaining({ type: 'reveal' }))
+  })
+
+  it('分屏同时看着：文件改了照常马上更新', async () => {
+    const { provider, document } = opening()
+    const page = tab()
+    provider.resolveCustomTextEditor(document as never, page.panel)
+    await page.send({ type: 'ready' })
+
+    page.clear()
+    edit(document, 2)
     await vi.waitFor(() => expect(page.posted()).toContainEqual(expect.objectContaining({ type: 'document', version: 2 })))
   })
 

vscode/src/codeReader/editor/previewEditor.ts

@@ -104,7 +104,7 @@ export class PreviewEditorProvider implements CustomTextEditorProvider {
   ) {}
 
   /**
-   * 注册成预览编辑器。标签页切走时页面留着（`retainContextWhenHidden`）：切回来不用重新生成、重发文档，页面也不用整份重画，
+   * 注册成预览编辑器。标签页切走时页面留着（`retainContextWhenHidden`）：切回来不用重新生成、重发文档（切走期间改过的才补一次），页面也不用整份重画，
    * 代价是每个开着的预览切走后仍占着它那个页面的内存。
    */
   register(): Disposable {
@@ -183,10 +183,14 @@ export class PreviewEditorProvider implements CustomTextEditorProvider {
 
 class Preview {
   /**
-   * 页面发过 ready（装好了、能收消息）之后才发消息。标签页切走时页面留着，照常收消息，切回来什么都不用补；
+   * 页面发过 ready（装好了、能收消息）之后才发消息。标签页切走时页面留着，照常收消息；
    * 页面真的重新加载了（webview 进程崩了重建、开发者重载 webview）会再发 ready，那时整份重发
    */
   private ready = false
+  /** 切走期间该重新生成的文档没生成（文件改了、规则变了）：重新看得见时补一次；没过期的切回来什么都不用做 */
+  private outdated = false
+  /** 页面上那份文档的版本：还不是眼下这一版时（正在生成、切走期间改过），要滚到的位置等新的那份一起带过去 */
+  private shown: number | undefined
   /** 侧栏「问 AI」打开的：页面准备好后把光标放进顶部输入框 */
   private pendingPathFocus = false
   /** 解析是异步的：只发最后一次请求的结果，慢的旧结果不能盖掉新的 */
@@ -226,7 +230,7 @@ class Preview {
   /** 这份文件相比对比基准改了什么：发完文档再算、补发 */
   private readonly diff: PreviewDiff
   /**
-   * 随下一份真正发出去的文档走、只走一次：新预览第一份文档要滚到的位置，或页面 ready 之前又来的 reveal。
+   * 随下一份真正发出去的文档走、只走一次：新预览第一份文档要滚到的位置，或页面上还不是眼下这一版文档时来的 reveal。
    * 之后页面真的重新加载了，按 webview 自己记的位置恢复
    */
   private pendingReveal: Reveal | undefined
@@ -271,6 +275,10 @@ class Preview {
           void this.diff.update(this.sent)
       }),
       panel.webview.onDidReceiveMessage((msg: WebviewToExtension) => this.handleMessage(msg)),
+      panel.onDidChangeViewState(() => {
+        if (panel.visible && this.outdated)
+          void this.push()
+      }),
       workspace.onDidChangeTextDocument((e) => {
         if (e.document !== document || e.contentChanges.length === 0)
           return
@@ -366,12 +374,19 @@ class Preview {
     clearTimeout(this.timer)
     if (!this.ready)
       return
+    // 切走的预览不在后台生成，后面跟着文档的查询也不起；分屏同时看得见的照常马上生成
+    if (!this.panel.visible) {
+      this.outdated = true
+      return
+    }
+    this.outdated = false
     const request = ++this.latest
     // 路径页、功能对话页：文档是空的，只在顶部聊天
     if (this.document.uri.scheme === PATH_PREVIEW_SCHEME) {
       this.sent = undefined
       const reveal = this.pendingReveal
       this.pendingReveal = undefined
+      this.shown = this.document.version
       this.post({
         type: 'document',
         version: this.document.version,
@@ -401,6 +416,7 @@ class Preview {
     this.imports = imports
     const reveal = this.pendingReveal
     this.pendingReveal = undefined
+    this.shown = version
     this.post({ ...message, names: this.names.known(version), ...(reveal && { reveal }) })
     if (this.sent)
       void this.diff.update(this.sent)
@@ -513,9 +529,9 @@ class Preview {
       this.focusPathAsk()
   }
 
-  /** 滚到 reveal：页面 ready 了就直接发，还没 ready 就等它发 ready 后随文档带过去。 */
+  /** 滚到 reveal：页面上已是眼下这一版文档就直接发；还不是（还没 ready、正在生成、切走期间改过）就随新的那份文档带过去。 */
   private reveal(reveal: Reveal): void {
-    if (this.ready)
+    if (this.shown === this.document.version)
       this.post({ type: 'reveal', ...reveal })
     else
       this.pendingReveal = reveal