MySQL UDS Support

[pimeys]

• Adds support for Unix Domain Sockets on MySQL
• Allows setting the socket path in PostgreSQL connection options
• ... and MySQL connection options

Fixes issue #449

[yoshuawuyts]

Did a light code review -- I don't know enough about the workings of SQLx to comment on the correctness, but hopefully this is still useful.

[yoshuawuyts]

Neat -- this is how std works these days as well. Also opens up the option to later enable it on Windows.

[pimeys]

Tested mysql with a test app, running mariadb locally and there's a socket file:

srwxrwxrwx 1 mysql mysql 0 Jun 25 16:05 /run/mysqld/mysqld.sock=

A test app with a simple select:

use sqlx::{Connect, MySqlConnection};

#[async_std::main]
async fn main() -> anyhow::Result<()> {
    let mut conn = MySqlConnection::connect("mysql://root@localhost/mysql?socket=/run/mysqld/mysqld.sock").await?;

    let row = sqlx::query("SELECT 1").fetch_one(&mut conn).await?;
    dbg!(row);

    Ok(())
}

Seems to connect and output the row.

[pimeys]

There's a slight problem with PostgreSQL here, having a socket in /var/run/

srwxrwxrwx  1 postgres postgres    0 Jun 25 16:55 .s.PGSQL.5433

Now my test app is this:

use sqlx::{Connect, PgConnection, Row};

#[async_std::main]
async fn main() -> anyhow::Result<()> {
    let mut conn =
        PgConnection::connect("postgresql://postgres@localhost:5433/postgres?host=/var/run/postgresql").await?;

    let row = sqlx::query("SELECT 1 as val").fetch_one(&mut conn).await?;
    let val: i32 = row.get("val");

    dbg!(val);

    Ok(())
}

If I don't specity the hostname, I'm getting an error:

Error: error occurred while parsing a connection string: empty host

Caused by:
    empty host

Seems like the url parsing doesn't like when the hostname is missing. If I add localhost it connects using the socket, working correctly.

[mehcode]

Looks good to me. Thank you for cleaning up and generalizing the UDS code @pimeys ❤️

[abonander]

Woops, our CI didn't catch this.

[abonander]

Pushed a fix to master.