40 lines
980 B
V
40 lines
980 B
V
|
import context
|
||
|
|
|
||
|
|
// This example demonstrates the use of a cancelable context to prevent a
|
||
|
|
// routine leak. By the end of the example function, the routine started
|
||
|
|
// by gen will return without leaking.
|
||
|
|
fn test_with_cancel() {
|
||
|
|
// gen generates integers in a separate routine and
|
||
|
|
// sends them to the returned channel.
|
||
|
|
// The callers of gen need to cancel the context once
|
||
|
|
// they are done consuming generated integers not to leak
|
||
|
|
// the internal routine started by gen.
|
||
|
|
gen := fn (mut ctx context.CancelerContext) chan int {
|
||
|
|
dst := chan int{}
|
||
|
|
go fn (mut ctx context.CancelerContext, dst chan int) {
|
||
|
|
ch := ctx.done()
|
||
|
|
loop: for i in 0 .. 5 {
|
||
|
|
select {
|
||
|
|
_ := <-ch {
|
||
|
|
// returning not to leak the routine
|
||
|
|
break loop
|
||
|
|
}
|
||
|
|
dst <- i {}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}(mut ctx, dst)
|
||
|
|
return dst
|
||
|
|
}
|
||
|
|
|
||
|
|
mut ctx := context.with_cancel(context.background())
|
||
|
|
defer {
|
||
|
|
context.cancel(mut ctx)
|
||
|
|
}
|
||
|
|
|
||
|
|
ch := gen(mut ctx)
|
||
|
|
for i in 0 .. 5 {
|
||
|
|
v := <-ch
|
||
|
|
assert i == v
|
||
|
|
}
|
||
|
|
}
|