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https://github.com/VictoriaMetrics/VictoriaMetrics.git
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76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
package bytesutil
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import (
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"math/bits"
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"unsafe"
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)
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// ResizeWithCopyMayOverallocate resizes b to minimum n bytes and returns the resized buffer (which may be newly allocated).
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//
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// If newly allocated buffer is returned then b contents is copied to it.
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func ResizeWithCopyMayOverallocate(b []byte, n int) []byte {
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if n <= cap(b) {
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return b[:n]
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}
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nNew := roundToNearestPow2(n)
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bNew := make([]byte, nNew)
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copy(bNew, b)
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return bNew[:n]
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}
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// ResizeWithCopyNoOverallocate resizes b to exactly n bytes and returns the resized buffer (which may be newly allocated).
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//
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// If newly allocated buffer is returned then b contents is copied to it.
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func ResizeWithCopyNoOverallocate(b []byte, n int) []byte {
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if n <= cap(b) {
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return b[:n]
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}
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bNew := make([]byte, n)
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copy(bNew, b)
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return bNew
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}
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// ResizeNoCopyMayOverallocate resizes b to minimum n bytes and returns the resized buffer (which may be newly allocated).
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//
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// If newly allocated buffer is returned then b contents isn't copied to it.
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func ResizeNoCopyMayOverallocate(b []byte, n int) []byte {
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if n <= cap(b) {
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return b[:n]
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}
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nNew := roundToNearestPow2(n)
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bNew := make([]byte, nNew)
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return bNew[:n]
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}
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// ResizeNoCopyNoOverallocate resizes b to exactly n bytes and returns the resized buffer (which may be newly allocated).
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//
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// If newly allocated buffer is returned then b contents isn't copied to it.
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func ResizeNoCopyNoOverallocate(b []byte, n int) []byte {
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if n <= cap(b) {
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return b[:n]
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}
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return make([]byte, n)
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}
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// roundToNearestPow2 rounds n to the nearest power of 2
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//
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// It is expected that n > 0
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func roundToNearestPow2(n int) int {
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pow2 := uint8(bits.Len(uint(n - 1)))
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return 1 << pow2
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}
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// ToUnsafeString converts b to string without memory allocations.
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//
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// The returned string is valid only until b is reachable and unmodified.
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func ToUnsafeString(b []byte) string {
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return unsafe.String(unsafe.SliceData(b), len(b))
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}
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// ToUnsafeBytes converts s to a byte slice without memory allocations.
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//
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// The returned byte slice is valid only until s is reachable and unmodified.
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func ToUnsafeBytes(s string) []byte {
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return unsafe.Slice(unsafe.StringData(s), len(s))
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}
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