atomic/cacheline.go

// Copyright (c) 2020-2025 Lux Industries, Inc.
//
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// of this software and associated documentation files (the "Software"), to deal
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//
// The above copyright notice and this permission notice shall be included in
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// THE SOFTWARE.

package atomic

import (
	"sync/atomic"
	"unsafe"
)

// CacheLineSize is the CPU cache line size in bytes.
// 64 bytes is the most common cache line size for modern CPUs.
const CacheLineSize = 64

// PaddedUint64 is like atomic.Uint64 but padded to prevent false sharing.
// Use this for high-contention counters accessed by multiple goroutines.
type PaddedUint64 struct {
	_ [CacheLineSize - unsafe.Sizeof(atomic.Uint64{})%CacheLineSize]byte
	atomic.Uint64
	_ [CacheLineSize - unsafe.Sizeof(atomic.Uint64{})%CacheLineSize]byte
}

// PaddedInt64 is like atomic.Int64 but padded to prevent false sharing.
type PaddedInt64 struct {
	_ [CacheLineSize - unsafe.Sizeof(atomic.Int64{})%CacheLineSize]byte
	atomic.Int64
	_ [CacheLineSize - unsafe.Sizeof(atomic.Int64{})%CacheLineSize]byte
}

// PaddedUint32 is like atomic.Uint32 but padded to prevent false sharing.
type PaddedUint32 struct {
	_ [CacheLineSize - unsafe.Sizeof(atomic.Uint32{})%CacheLineSize]byte
	atomic.Uint32
	_ [CacheLineSize - unsafe.Sizeof(atomic.Uint32{})%CacheLineSize]byte
}

// PaddedInt32 is like atomic.Int32 but padded to prevent false sharing.
type PaddedInt32 struct {
	_ [CacheLineSize - unsafe.Sizeof(atomic.Int32{})%CacheLineSize]byte
	atomic.Int32
	_ [CacheLineSize - unsafe.Sizeof(atomic.Int32{})%CacheLineSize]byte
}

// PaddedBool is like atomic.Bool but padded to prevent false sharing.
type PaddedBool struct {
	_ [CacheLineSize - unsafe.Sizeof(atomic.Bool{})%CacheLineSize]byte
	atomic.Bool
	_ [CacheLineSize - unsafe.Sizeof(atomic.Bool{})%CacheLineSize]byte
}