47 lines
1.0 KiB
V
47 lines
1.0 KiB
V
// vtest retry: 3
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import context
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// This example demonstrates the use of a cancelable context to prevent a
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// routine leak. By the end of the example function, the routine started
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// by gen will return without leaking.
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fn test_with_cancel() {
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// gen generates integers in a separate routine and
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// sends them to the returned channel.
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// The callers of gen need to cancel the context once
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// they are done consuming generated integers not to leak
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// the internal routine started by gen.
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gen := fn (mut ctx context.Context) chan int {
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dst := chan int{}
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go fn (mut ctx context.Context, dst chan int) {
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mut v := 0
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ch := ctx.done()
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for {
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select {
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_ := <-ch {
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// returning not to leak the routine
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return
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}
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dst <- v {
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v++
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}
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}
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}
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}(mut ctx, dst)
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return dst
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}
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mut background := context.background()
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mut ctx, cancel := context.with_cancel(mut &background)
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defer {
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cancel()
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}
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mut mut_ctx := ctx
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mut ctx2 := &mut_ctx
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ch := gen(mut ctx2)
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for i in 0 .. 5 {
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v := <-ch
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assert i == v
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}
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}
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