7a469725d3 Refactor BufferDiff to allow multiple diffs to share the same base text buffer (#58266)
This PR changes how base texts are managed by the `buffer_diff` crate,
to enable keeping two diff entities alive that share the same base text
buffer entity. Previously, each diff owned its own base text buffer and
edited it when calling `BufferDiff::set_snapshot`, so the only way to
reuse the same base text between two diffs was to have two independent
buffers for it, which is pretty inefficient.

After this PR, each diff still has a base text buffer, but
`set_snapshot` doesn't edit it. Instead, that responsibility moves into
the caller. For updating the base text buffer, this PR also introduces a
new pair of APIs, `Buffer::snapshot_with_edits` and
`Buffer::fast_forward`, which allow us to move the parsing of the new
base text into the background and then install the new syntax tree
synchronously on the foreground.

The git store uses the low-level APIs `set_snapshot` and `fast_forward`
directly, and manages the head text and index text buffers itself
(garbage-collecting them when they're no longer needed); this enables
adding an `open_staged_diff` API which returns a diff between the
managed index buffer and the managed head buffer (the latter is also
used for the uncommitted diff's base text). Other downstreams don't need
to reuse a base text buffer, and those have been migrated to use the
high-level `set_base_text` API, which now calls `set_snapshot` and
`fast_forward` internally, with a guard to prevent concurrent updates.

Another change worthy of note is that we now always diff the old base
text with the new base text to create `snapshot_with_edits`.

There are also some incidental bug fixes:
- Fixed an issue where a dangling weak unstaged diff could stick around
in the git store forever
- Restored the `IndexMatchesHead` optimization that had become
inoperative in the remote case
- Fixed a crash in the multibuffer due to the handling of
`BufferDiffEvent::LanguageChanged`, which could cause the multibuffer to
have transforms that were inconsistent with the diff base text.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Closes ZED-81P

Release Notes:

- Fixed a rare crash that could occur while using the uncommitted diff.

---------

Co-authored-by: Ben Kunkle <ben@zed.dev>
Co-authored-by: Anthony Eid <hello@anthonyeid.me>
2026-06-09 20:13:13 +00:00
2026-04-30 11:10:14 +00:00
2026-06-05 23:12:31 +00:00
2026-05-27 18:17:59 +00:00
2026-01-22 23:57:26 +05:30
WIP
2023-12-14 09:25:14 -07:00
2026-04-29 10:27:47 +00:00
2025-02-04 09:02:59 -05:00
2026-01-06 12:49:51 -08:00
2025-10-27 13:27:59 -04:00
2025-10-17 18:58:14 +00:00
2026-03-17 16:34:35 +00:00
2026-04-29 10:27:47 +00:00
2026-05-27 16:27:18 +00:00

Zed

Zed CI

Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.


Installation

On macOS, Linux, and Windows you can download Zed directly or install Zed via your local package manager (macOS/Linux/Windows).

Other platforms are not yet available:

Developing Zed

Contributing

See CONTRIBUTING.md for ways you can contribute to Zed.

Also... we're hiring! Check out our jobs page for open roles.

Licensing

Zed source code is licensed primarily under GPL-3.0-or-later, with Apache-2.0 components where marked.

License information for third party dependencies must be correctly provided for CI to pass.

We use cargo-about to automatically comply with open source licenses. If CI is failing, check the following:

  • Is it showing a no license specified error for a crate you've created? If so, add publish = false under [package] in your crate's Cargo.toml.
  • Is the error failed to satisfy license requirements for a dependency? If so, first determine what license the project has and whether this system is sufficient to comply with this license's requirements. If you're unsure, ask a lawyer. Once you've verified that this system is acceptable add the license's SPDX identifier to the accepted array in script/licenses/zed-licenses.toml.
  • Is cargo-about unable to find the license for a dependency? If so, add a clarification field at the end of script/licenses/zed-licenses.toml, as specified in the cargo-about book.

Sponsorship

Zed is developed by Zed Industries, Inc., a for-profit company.

If you’d like to financially support the project, you can do so via GitHub Sponsors. Sponsorships go directly to Zed Industries and are used as general company revenue. There are no perks or entitlements associated with sponsorship.

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