fix: memory leak in search results

[Simon Siefke (SimonSiefke)]

Fixes a memory leak in search results by moving the hover to elementDisposables instead of templateDisposables.

Since the hover listeners are created in renderElement, it seems they also should be added to elementDisposables, similar to other list renderers in the file.

Before

When running workspace search and replace 17 times, several event listener leaks are found:

{
  "eventListenersWithStackTrace": [
    {
      "type": "focus",
      "description": "(e) => {\n      if (isMouseDown || hoverPreparation) {\n        return;\n      }\n      if (!eventIsRelatedToTarget(e, targetElement)) {\n        return;\n      }\n      const target = {\n        targetElements: [targetElement],\n        dispose: () => {\n        }\n      };\n      const toDispose = new DisposableStore();\n      const onBlur = () => hideHover(true, true);\n      toDispose.add(addDisposableListener(targetElement, EventType.BLUR, onBlur, true));\n      toDispose.add(triggerShowHover(typeof hoverDelegate.delay === \"function\" ? hoverDelegate.delay(content) : hoverDelegate.delay, false, target));\n      hoverPreparation = toDispose;\n    }",
      "objectId": "1326115614926442416.1.23079",
      "stack": [
        "listener (vscode/out/vs/platform/hover/browser/hoverService.js:376:20)",
        "new DomListener (vscode/out/vs/base/browser/dom.js:106:16)",
        "addDisposableListener (vscode/out/vs/base/browser/dom.js:118:10)",
        "HoverService.setupManagedHover (vscode/out/vs/platform/hover/browser/hoverService.js:396:17)",
        "MatchRenderer.renderElement (vscode/out/vs/workbench/contrib/search/browser/searchResultsView.js:359:52)",
        "CompressibleAsyncDataTreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/asyncDataTree.js:1099:19)",
        "CompressibleRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/objectTree.js:75:21)",
        "_TreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/abstractTree.js:315:19)",
        "PipelineRenderer.renderElement (vscode/out/vs/base/browser/ui/list/listWidget.js:920:16)"
      ],
      "count": 412,
      "originalStack": ["/vscode/src/vs/platform/hover/browser/hoverService.ts:471:19"],
      "originalName": null
    },
    {
      "type": "focus",
      "description": "(e) => {\n      if (isMouseDown || hoverPreparation) {\n        return;\n      }\n      if (!eventIsRelatedToTarget(e, targetElement)) {\n        return;\n      }\n      const target = {\n        targetElements: [targetElement],\n        dispose: () => {\n        }\n      };\n      const toDispose = new DisposableStore();\n      const onBlur = () => hideHover(true, true);\n      toDispose.add(addDisposableListener(targetElement, EventType.BLUR, onBlur, true));\n      toDispose.add(triggerShowHover(typeof hoverDelegate.delay === \"function\" ? hoverDelegate.delay(content) : hoverDelegate.delay, false, target));\n      hoverPreparation = toDispose;\n    }",
      "objectId": "1326115614926442416.1.24229",
      "stack": [
        "listener (vscode/out/vs/platform/hover/browser/hoverService.js:376:20)",
        "new DomListener (vscode/out/vs/base/browser/dom.js:106:16)",
        "addDisposableListener (vscode/out/vs/base/browser/dom.js:118:10)",
        "HoverService.setupManagedHover (vscode/out/vs/platform/hover/browser/hoverService.js:396:17)",
        "MatchRenderer.renderElement (vscode/out/vs/workbench/contrib/search/browser/searchResultsView.js:367:52)",
        "CompressibleAsyncDataTreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/asyncDataTree.js:1099:19)",
        "CompressibleRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/objectTree.js:75:21)",
        "_TreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/abstractTree.js:315:19)",
        "PipelineRenderer.renderElement (vscode/out/vs/base/browser/ui/list/listWidget.js:920:16)"
      ],
      "count": 412,
      "originalStack": ["vscode/src/vs/platform/hover/browser/hoverService.ts:471:19"],
      "originalName": null
    },
    {
      "type": "mouseover",
      "description": "(e) => {\n      if (hoverPreparation) {\n        return;\n      }\n      const mouseOverStore = new DisposableStore();\n      const target = {\n        targetElements: [targetElement],\n        dispose: () => {\n        }\n      };\n      if (hoverDelegate.placement === void 0 || hoverDelegate.placement === \"mouse\") {\n        const onMouseMove = (e2) => {\n          target.x = e2.x + 10;\n          if (!eventIsRelatedToTarget(e2, targetElement)) {\n            hideHover(true, true);\n          }\n        };\n        mouseOverStore.add(addDisposableListener(targetElement, EventType.MOUSE_MOVE, onMouseMove, true));\n      }\n      hoverPreparation = mouseOverStore;\n      if (!eventIsRelatedToTarget(e, targetElement)) {\n        return;\n      }\n      mouseOverStore.add(triggerShowHover(typeof hoverDelegate.delay === \"function\" ? hoverDelegate.delay(content) : hoverDelegate.delay, false, target));\n    }",
      "objectId": "1326115614926442416.1.22849",
      "stack": [
        "listener (vscode/out/vs/platform/hover/browser/hoverService.js:351:73)",
        "new DomListener (vscode/out/vs/base/browser/dom.js:106:16)",
        "addDisposableListener (vscode/out/vs/base/browser/dom.js:118:10)",
        "HoverService.setupManagedHover (vscode/out/vs/platform/hover/browser/hoverService.js:352:15)",
        "MatchRenderer.renderElement (vscode/out/vs/workbench/contrib/search/browser/searchResultsView.js:359:52)",
        "CompressibleAsyncDataTreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/asyncDataTree.js:1099:19)",
        "CompressibleRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/objectTree.js:75:21)",
        "_TreeRenderer.renderElement (vscode/out/vs/base/browser/ui/tree/abstractTree.js:315:19)",
        "PipelineRenderer.renderElement (vscode/out/vs/base/browser/ui/list/listWidget.js:920:16)"
      ],
      "count": 412,
      "originalStack": ["vscode/src/vs/platform/hover/browser/hoverService.ts:440:72"],
      "originalName": null
    },
}

After

When searching, no more event listener leaks are detected

[Copilot]

Pull request overview

This PR fixes an event-listener memory leak in the Search results tree by ensuring hover listeners created during renderElement are disposed when an element is recycled, aligning MatchRenderer with the established renderer pattern in this file.

Changes:

• Add elementDisposables to IMatchTemplate and initialize it in MatchRenderer.renderTemplate.
• Register managed hovers into elementDisposables (instead of disposables) in renderElement.
• Implement disposeElement to clear() per-element disposables on element disposal.

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[Copilot]

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0 new

[Dmitriy Vasyura (dmitrivMS)]

Simon Siefke (@SimonSiefke) Thank you!

[Emre (SeanTolstoyevski)]

thanks team for the quick fix.

I reviewed the pr and the work done and I have a suggestion:
can a test be added to prevent this type of regression from occurring? does vscode have such an infrastructure?