zed/crates/terminal_view
Thorsten Ball c4cf5f2b2c Upgrade alacritty_terminal in hopes to avoid PTY poll failing
We saw stack traces in our #panic channel pop up that failed on this line:

    3330614219/alacritty_terminal/src/event_loop.rs (L323-L324)

With this message:

    thread 'PTY reader' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 9, kind: Uncategorized, message: "Bad file descriptor" }'
    /Users/administrator/.cargo/git/checkouts/alacritty-afea874b09a502a5/3330614/alacritty_terminal/src/event_loop.rs:324

We don't know how to reproduce the error. It doesn't seem related to the number of open PTY handles,
because `openpty` itself didn't fail. We can only assume that something went wrong between
`openpty` and the setup of the polling.

Since Alacritty itself changed its polling mechanism significantly by switching
from `mio` to `polling` (https://github.com/alacritty/alacritty/pull/6846) we upgraded
with the hope that this will fix the bug.

Co-authored-by: Antonio <antonio@zed.dev>
Co-authored-by: Federico <code@fdionisi.me>
Co-authored-by: David <dammerung2718@icloud.com>
Co-authored-by: Bennet <bennetbo@gmx.de>
2024-01-26 09:38:05 +01:00
..
scripts Fix typos 2023-06-02 22:02:19 -04:00
src Upgrade alacritty_terminal in hopes to avoid PTY poll failing 2024-01-26 09:38:05 +01:00
Cargo.toml chore: Change AGPL-licensed crates to GPL (except for collab) (#4231) 2024-01-24 00:26:58 +01:00
LICENSE-GPL chore: Change AGPL-licensed crates to GPL (except for collab) (#4231) 2024-01-24 00:26:58 +01:00
README.md vim . to replay 2023-09-06 13:49:55 -06:00

Design notes:

This crate is split into two conceptual halves:

  • The terminal.rs file and the src/mappings/ folder, these contain the code for interacting with Alacritty and maintaining the pty event loop. Some behavior in this file is constrained by terminal protocols and standards. The Zed init function is also placed here.
  • Everything else. These other files integrate the Terminal struct created in terminal.rs into the rest of GPUI. The main entry point for GPUI is the terminal_view.rs file and the modal.rs file.

ttys are created externally, and so can fail in unexpected ways. However, GPUI currently does not have an API for models than can fail to instantiate. TerminalBuilder solves this by using Rust's type system to split tty instantiation into a 2 step process: first attempt to create the file handles with TerminalBuilder::new(), check the result, then call TerminalBuilder::subscribe(cx) from within a model context.

The TerminalView struct abstracts over failed and successful terminals, passing focus through to the associated view and allowing clients to build a terminal without worrying about errors.

#Input

There are currently many distinct paths for getting keystrokes to the terminal:

  1. Terminal specific characters and bindings. Things like ctrl-a mapping to ASCII control character 1, ANSI escape codes associated with the function keys, etc. These are caught with a raw key-down handler in the element and are processed immediately. This is done with the try_keystroke() method on Terminal

  2. GPU Action handlers. GPUI clobbers a few vital keys by adding bindings to them in the global context. These keys are synthesized and then dispatched through the same try_keystroke() API as the above mappings

  3. IME text. When the special character mappings fail, we pass the keystroke back to GPUI to hand it to the IME system. This comes back to us in the View::replace_text_in_range() method, and we then send that to the terminal directly, bypassing try_keystroke().

  4. Pasted text has a separate pathway.

Generally, there's a distinction between 'keystrokes that need to be mapped' and 'strings which need to be written'. I've attempted to unify these under the '.try_keystroke()' API and the .input() API (which try_keystroke uses) so we have consistent input handling across the terminal