When exactly does the __MISE_WATCH or __MISE_DIFF env variable change?

[ffittschen]

Hi all,
I'm curious when exactly the __MISE_WATCH or __MISE_DIFF environment variable changes.

When tracking down some issues with the Swift Package Manager that appeared after installing mise, I discovered that SPM actually uses the environment as input for their cache key (see implementation, discussion). In Swift 5.10, they actually added a filter to remove some env variables, which change very often, which led me to debug my env variables.

I ran printenv twice while waiting 1 minute between the invocations and observed that the __MISE_WATCH env variable changed, without me touching anything on the system. That's why I'm asking the question.

[jdx]

that is actually a very difficult question to answer—I have no idea. The code doesn't "change" it, it generates it every time the prompt is displayed. You'd have to trace the code to see.

If it's a problem you could just not use mise activate.

[ffittschen]

I traced the code to the config.watch_files() function.

As far as I can see, it takes the following as input:

• all config files paths
• all resolved env_files paths
• all resolved env_scripts paths
• the global MISE_ENV_FILE path

As this still a bit vague, I just looked into deserializing the __MISE_WATCH value manually¹, resulting in this structure

files:
  /Users/<username>/.config/mise/config.toml: <modified timestamp>
  /Users/<username>/.local/share/mise: <modified timestamp>
  /Users/<username>/<project-dir>/.mise.toml: <modified timestamp>
  /Users/<username>/<project-dir>/Gemfile: <modified timestamp>
env_var_hash: 37a317d896eaf472

What I do not understand is why the value of __MISE_WATCH changes if I don't touch any of those files mentioned above. The env_var_hash should also stay the same as the only env var starting with MISE_ is MISE_SHELL, which is static.

From running the command again after waiting a while, I can see that the value mise sets as the modified timestamp of the /Users/<username>/.local/share/mise directory changes, but when running stat /Users/<username>/.local/share/mise, the mtime value stays the same...

Do you have an idea what could modify the /Users/<username>/.local/share/mise directory?

Footnotes

1. echo "$__MISE_WATCH" | base64 --decode | pigz -d -z --fast ↩

[jdx]

yeah, it gets touched right here:

mise/src/cli/activate.rs

Line 61 in ef25cb1

let _ = touch_dir(&dirs::DATA);

but are you actually running mise activate somewhere?

it also gets touched here:

mise/src/cli/activate.rs

Line 61 in ef25cb1

let _ = touch_dir(&dirs::DATA);

but that is when installing tools

[jdx]

might be worth trying removing those lines and seeing if that stops the mtime from changing