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// Channel Benchmark
//
// `nobj` integers are sent thru a channel with queue length`buflen`
// using `nsend` sender threads and `nrec` receiver threads.
//
// The receive threads add all received numbers and send them to the
// main thread where the total sum is compare to the expected value.
import time
import os
fn do_rec(ch chan int, resch chan i64, n int) {
mut sum := i64(0)
for _ in 0 .. n {
sum += <-ch
}
println(sum)
resch <- sum
}
fn do_send(ch chan int, start int, end int) {
for i in start .. end {
ch <- i
}
}
fn main() {
if os.args.len != 5 {
eprintln('usage:\n\t${os.args[0]} <nsend> <nrec> <buflen> <nobj>')
exit(1)
}
nsend := os.args[1].int()
nrec := os.args[2].int()
buflen := os.args[3].int()
nobj := os.args[4].int()
stopwatch := time.new_stopwatch()
ch := chan int{cap: buflen}
resch := chan i64{}
mut no := nobj
for i in 0 .. nrec {
n := no / (nrec - i)
go do_rec(ch, resch, n)
no -= n
}
assert no == 0
no = nobj
for i in 0 .. nsend {
n := no / (nsend - i)
end := no
no -= n
go do_send(ch, no, end)
}
assert no == 0
mut sum := i64(0)
for _ in 0 .. nrec {
sum += <-resch
}
elapsed := stopwatch.elapsed()
rate := f64(nobj) / elapsed * time.microsecond
println('$nobj objects in ${f64(elapsed) / time.second} s (${rate:.2f} objs/µs)')
// use sum formula by Gauß to calculate the expected result
expected_sum := i64(nobj) * (nobj - 1) / 2
println('got: $sum, expected: $expected_sum')
assert sum == expected_sum
}
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