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modify the elements in the array directly without allocating a new array #97964

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merged 1 commit into from Apr 23, 2021
Merged

modify the elements in the array directly without allocating a new array #97964

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9 changes: 2 additions & 7 deletions staging/src/k8s.io/client-go/tools/cache/delta_fifo.go
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Expand Up @@ -373,13 +373,8 @@ func dedupDeltas(deltas Deltas) Deltas {
a := &deltas[n-1]
b := &deltas[n-2]
if out := isDup(a, b); out != nil {
// `a` and `b` are duplicates. Only keep the one returned from isDup().
// TODO: This extra array allocation and copy seems unnecessary if
// all we do to dedup is compare the new delta with the last element
// in `items`, which could be done by mutating `items` directly.
// Might be worth profiling and investigating if it is safe to optimize.
d := append(Deltas{}, deltas[:n-2]...)
return append(d, *out)
deltas[n-2] = *out
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the signature of dedupDeltas does not make it obvious the input slice will be modified... that seems like it could be surprising or lead to subtle bugs

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I think the old code overwrote deltas[n-2] already, though.

OK fine I verified that append works like I thought: https://play.golang.org/p/9n1QmE8VxdT

return deltas[:n-1]
}
return deltas
}
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