watt: implement single-instance lock mechanism for watt daemon#47
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Signed-off-by: NotAShelf <raf@notashelf.dev> Change-Id: Ideaf221f690c7bc694ca1f171385bfde6a6a6964
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Bro burnt the pan after review 😭
| .map(|dir| PathBuf::from(dir).join("watt.pid")) | ||
| .unwrap_or_else(|_| PathBuf::from("/run/watt.pid")); | ||
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| let _lock = lock::LockFile::acquire(&lock_path, cli.force).context( |
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with_context, otherwise you're allocating each time even on no error
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| let lock_path = env::var("XDG_RUNTIME_DIR") | ||
| .map(|dir| PathBuf::from(dir).join("watt.pid")) | ||
| .unwrap_or_else(|_| PathBuf::from("/run/watt.pid")); |
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Why not .join("watt.pid") at the end?
let lock_path = env::var_os("XDG_RUNTIME_DIR"). map_or_else(PathBuf::new, || PathBuf::new("/run")).join("watt.pid")
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This was probably something we should've implemented earlier. While not too likely, it's possible that there will be multiple Watt instances running simultaneously, which can create access issues if two of them try to write a sysfs path at the same time. This PR introduces process locking to the Watt daemon in order to prevent multiple instances from running simultaneously.
This is done in the new
watt::lockmodule that manages a PID file lock, and a new--forceflag has been added for when this behaviour is explicitly desired.Change-Id: Ideaf221f690c7bc694ca1f171385bfde6a6a6964