5387747e92
Bumps [github.com/containerd/cgroups/v3](https://github.com/containerd/cgroups) from 3.0.2 to 3.0.3. - [Release notes](https://github.com/containerd/cgroups/releases) - [Commits](https://github.com/containerd/cgroups/compare/v3.0.2...v3.0.3) --- updated-dependencies: - dependency-name: github.com/containerd/cgroups/v3 dependency-type: direct:production update-type: version-update:semver-patch ... Signed-off-by: dependabot[bot] <support@github.com>
92 lines
1.7 KiB
Go
92 lines
1.7 KiB
Go
package internal
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import "math/bits"
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// Deque implements a double ended queue.
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type Deque[T any] struct {
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elems []T
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read, write uint64
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mask uint64
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}
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// Reset clears the contents of the deque while retaining the backing buffer.
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func (dq *Deque[T]) Reset() {
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var zero T
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for i := dq.read; i < dq.write; i++ {
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dq.elems[i&dq.mask] = zero
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}
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dq.read, dq.write = 0, 0
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}
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func (dq *Deque[T]) Empty() bool {
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return dq.read == dq.write
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}
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// Push adds an element to the end.
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func (dq *Deque[T]) Push(e T) {
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dq.Grow(1)
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dq.elems[dq.write&dq.mask] = e
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dq.write++
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}
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// Shift returns the first element or the zero value.
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func (dq *Deque[T]) Shift() T {
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var zero T
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if dq.Empty() {
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return zero
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}
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index := dq.read & dq.mask
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t := dq.elems[index]
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dq.elems[index] = zero
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dq.read++
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return t
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}
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// Pop returns the last element or the zero value.
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func (dq *Deque[T]) Pop() T {
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var zero T
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if dq.Empty() {
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return zero
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}
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dq.write--
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index := dq.write & dq.mask
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t := dq.elems[index]
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dq.elems[index] = zero
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return t
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}
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// Grow the deque's capacity, if necessary, to guarantee space for another n
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// elements.
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func (dq *Deque[T]) Grow(n int) {
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have := dq.write - dq.read
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need := have + uint64(n)
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if need < have {
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panic("overflow")
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}
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if uint64(len(dq.elems)) >= need {
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return
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}
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// Round up to the new power of two which is at least 8.
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// See https://jameshfisher.com/2018/03/30/round-up-power-2/
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capacity := 1 << (64 - bits.LeadingZeros64(need-1))
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if capacity < 8 {
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capacity = 8
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}
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elems := make([]T, have, capacity)
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pivot := dq.read & dq.mask
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copied := copy(elems, dq.elems[pivot:])
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copy(elems[copied:], dq.elems[:pivot])
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dq.elems = elems[:capacity]
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dq.mask = uint64(capacity) - 1
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dq.read, dq.write = 0, have
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}
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