Cryptic error message if accounts.lock is locked

[Hocuri]

How this happened to me:

Due to some bug deltachat/deltachat-desktop#4748, DC Desktop crashed but the accounts.lock stayed locked.

How DC Desktop crashed

I don't remember exactly what I did, but it was something along these lines:

• Click "+" for new account
• Press ESC
• Try to select another account
• -> DC Desktop is completely frozen
• I closed DC

But when I try to reproduce this, everything works fine.

Steps to reproduce:

• Lock the accounts.lock file using flock /home/.../DeltaChat/accounts/accounts.lock --command "sleep 1000"
• Try to open Delta Chat

Actual behavior:

Expected behavior:

A nice error message should be shown.

Possible solutions:

• Make the error message nicer
• Remove the locking of accounts.lock (this would also get us rid of one dependency, fd-lock) (see create_lock_task() in accounts.rs)

[Simon-Laux]

issue on desktop repo for reference: deltachat/deltachat-desktop#4748

[Septias]

I invested this a bit and only the last part (after Fatal Error) is changeable in core/deltachat-rpc-server. The cryptic part originates (as @WofWca already pointed out in the desktop issue) from deltachat-desktop in this line https://github.com/deltachat/deltachat-desktop/blob/c0fdab6aa09dc640549d601077e3f44436fdcfc0/packages/target-electron/src/deltachat/stdio_server.ts#L96. So to solve this in core only the second proposal is a viable option.

[link2xt]

Remove the locking of accounts.lock (this would also get us rid of one dependency, fd-lock) (see create_lock_task() in accounts.rs)

When this happens, it is actually good that Delta Chat stops. If you forcefully unlock it while existing core is still running, both deltachat-rpc-server processes keep running, download messages and write each message to the database twice. The lock is working as intended.

From @hpk42 in desktop chat:

deleting the lock file was not enough -- i got double messages afterwards and it turned out there were two deltachat-rpc-server processes running. Had to kill the old one with "kill -9" to recover. Now everything is sane again.

[Hocuri]

I made a PR that makes the core side of this look nicer: #6695

I'll create an issue in Desktop for the rest.

[Hocuri]

Everything that's actionable for now has been done.