> But I dont realy want to create a new thread every time. So is there a better
> way of achieving this? (it may be linux specific)
Make the proc is always running the background as a dedicated thread but lock
it to save the cpu loop and only continue if the lock receiving signal.
For example here:
import std/[locks, strformat, times, threadpool, os]
var
chan: Channel[string]
cond: Cond
lock: Lock
let startTime = now()
initLock lock
initCond cond
chan.open
proc bgExec {.thread.} =
while true:
let data = tryRecv chan
if data.dataAvailable:
if data.msg == "": break
echo fmt"'{data.msg}' at duration {now() - startTime} from
{startTime}"
continue
cond.wait lock
template runit(msg: string) =
chan.send msg
cond.signal
proc main {.thread.} =
runit "start"
sleep 200
runit "after 200 ms"
sleep 100
runit "after 300 ms"
sleep 200
runit "after 500 ms"
runit "stop"
runit ""
spawn bgExec()
spawn main()
sync()
Run
In this example, channel is used to illustrate the stream of "what you want to
execute" but it can be anything. The key part is the `continue`,
`condition.wait(lock)` and `condition.signal()`
* `continue` is needed to immediately check whether there's another message
before waiting on lock
* waiting for lock is to avoid wasted cpu loop
* signal is to tell the condition it's ok stop waiting.
[Run it on playground](https://play.nim-lang.org/#ix=4EfX)
