.diesel_lock in migrations

[YievCkim]

Backend

PostgreSQL

Diesel version

2.2.0

Diesel Features

postgres

Operating System Version

Linux 6.14.0-111029-tuxedo x86_64 GNU/Linux

Third party libraries

serde = { version = "1.0", features = ["derive"] }

What do you want to do?

I have found a .diesel_lock file in the migrations directory after generate migration.
What is the purpose of this file ? Is it safe to delete it ?

Compile time error

No response

What code do you already have?

No response

Additional details

No response

Checklist

• I have already looked over the issue tracker and the discussion forum for similar possible closed issues.

[weiznich]

This file is used by diesel-cli for ensuring that only instance of diesel-cli tries to generate migrations at the same time. If you delete that file it will be recreated on the next run of diesel migration generate. Otherwise nothing bad happens.

[weiznich]

Most likely this file is not removed to be reused later. That written I also see no hard reason to keep it there, so we are happy to review a PR for automatically removing this file in the end of the operation.

[YievCkim]

I will try to give a look in the next days.

[lindes]

Would second a request for automatic removal. I'm still new enough to Rust that I don't feel especially comfortable coming up with a good PR, I think, though if it's otherwise not going to happen, I might be willing to give it a go.

[YievCkim]

@lindes If you want to work on it I see no problem. I am not sure I will have time to do it on my side.

[weiznich]

All that needs to be done in ensuring that the file returned by this function is removed on close. This likely can done by:

diesel/diesel_cli/src/migrations/mod.rs

Line 186 in ed01866

fn migration_folder_lock(dir: PathBuf) -> Result<File, crate::errors::Error> {

• Creating a wrapper type for File that removes the file on drop
• Ensure that it implements the relevant traits to use fd_lock::RwLock: https://docs.rs/fd-lock/latest/fd_lock/struct.RwLock.html. That's likely platform depended, but you can just forward all required impls to the inner File type.
• Return that type from the linked function