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break-time-hs

This is a rewrite of the core functionality of break-time in Haskell.

break-time is a Linux daemon that locks your screen and forces you to take breaks while working at your computer. I originally wrote break-time in Rust, but it slowly grew more and more complicated. The code is currently quite messy. It really could use a big refactoring, or even a complete rewrite.

This repository is a proof-of-concept rewrite in Haskell. Only the main logic for deciding when to take a break is implemented. All the plugins from the original version are not implemented.

The code from this repository isn't meant to be used as-is, but may be a good starting place for a rewrite or refactoring.

Use

This can be built with the following command:

$ stack build

break-time-hs provides a web server that you can use to start a break-time thread, query the current status of the break-time thread, as well as sending various commands. You can run the web server with the following command:

$ stack run
Setting phasers to stun... (port 3000) (ctrl-c to quit)

Start a break-time thread. This thread will count down for 15 seconds between breaks, and then break for 10 seconds:

$ curl -L -v -X POST localhost:3000/break-time
...
< HTTP/1.1 201 Created
...
< Location: /break-time/0
...

You can look at the status of the break-time thread:

$ curl -L -X GET localhost:3000/break-time/0
BreakTimeEnv: (break every 15s seconds, breaks last for 10s seconds): BTSWork (CountDown {timeLeft = 4.991127679s, prevTarget = 2022-02-20 09:59:33.140554161 UTC, countDownEndsAt = 2022-02-2 0 09:59:38.140554161 UTC}), threadStatus: ThreadBlocked BlockedOnMVar

You can pause and unpause the break-time thread work timer. Breaks won't occur while it is paused:

$ curl -L -v -X POST localhost:3000/break-time/0/pause
$ curl -L -v -X POST localhost:3000/break-time/0/unpause

You can reset the break-time work timer:

$ curl -L -v -X POST localhost:3000/break-time/0/reset

You can delete the currently running break-time thread:

$ curl -L -v -X DELETE localhost:3000/break-time/0

Design

The original break-time has multiple threads running at once, and uses channels for communication between threads. This worked well when break-time was simple, but has slowly grown out of control with all of the current functionality.

break-time-hs instead uses STM and TVars to communicate between multiple threads. This seems to be much simpler, and works well in practice.

The current implementation doesn't actually use the multiple-value mutation transation functionality of STM, but does make use of the retry function for blocking and waiting for changes (both directly and through use of TMVars).