Example in rust of the core part of foreman

It is an implementation example in rust of IO processing and signal processing in multithread as done by foreman of ruby.

• IO process in multi thread
• handle signlas in another thread
• child wait in another thread

Since it is a sample, unlike foreman, it does not have the flexibility to define a process in Procfile.
The processes that can be executed are as follows.

process	concurrency	command
exit_0	1	sleep 5 && echo 'success' && exit 0;
exit_1	1	sleep 5 && echo 'failed' && exit 1;
loop	2	while :; do sleep 1 && echo 'hello world'; done;

The behavior is that when exit_0 or exit_1 exits after 5 seconds, the remaining child processes will be signaled with a SIGTERM and killed.

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.08s
     Running `target/debug/eg_foreman`
system    | exit_0.1  start at pid: 11350
system    | loop.1    start at pid: 11351
system    | exit_1.1  start at pid: 11352
system    | loop.2    start at pid: 11353
loop.2    | hello world
loop.1    | hello world
loop.1    | hello world
loop.2    | hello world
loop.2    | hello world
loop.1    | hello world
loop.1    | hello world
loop.2    | hello world
exit_1.1  | failed
exit_0.1  | success
system    | sending SIGTERM for loop.1    at pid 11351
system    | sending SIGTERM for exit_1.1  at pid 11352
system    | sending SIGTERM for loop.2    at pid 11353
system    | exit 0

If ctrl-c is detected within 5 seconds, SIGTERM will be sent to all child processes and the process will be killed.

$ cargo run
    Finished dev [unoptimized + debuginfo] target(s) in 0.09s
     Running `target/debug/eg_foreman`
system    | exit_0.1  start at pid: 43204
system    | loop.1    start at pid: 43205
system    | exit_1.1  start at pid: 43206
system    | loop.2    start at pid: 43207
loop.2    | hello world
loop.1    | hello world
loop.1    | hello world
loop.2    | hello world
^Csystem  | ctrl-c detected
system    | sending SIGTERM for children
system    | sending SIGTERM for exit_0.1  at pid 43204
system    | sending SIGTERM for loop.1    at pid 43205
system    | sending SIGTERM for exit_1.1  at pid 43206
system    | sending SIGTERM for loop.2    at pid 43207
system    | exit 0

If you generalize this, you can make a foreman. You did it. 🎉

Development

Executte Test

cargo test
# or
cargo test -- --nocapture

Environment

name	desc	defaul
COLOR	Color the output	true

Reference

I really referred to the implementation of the following repository.

• fors
• arpx