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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package log // import "go.opentelemetry.io/otel/sdk/log"
// A ring is an element of a circular list, or ring. Rings do not have a
// beginning or end; a pointer to any ring element serves as reference to the
// entire ring. Empty rings are represented as nil ring pointers. The zero
// value for a ring is a one-element ring with a nil Value.
//
// This is copied from the "container/ring" package. It uses a Record type for
// Value instead of any to avoid allocations.
type ring struct {
next, prev *ring
Value Record
}
func (r *ring) init() *ring {
r.next = r
r.prev = r
return r
}
// Next returns the next ring element. r must not be empty.
func (r *ring) Next() *ring {
if r.next == nil {
return r.init()
}
return r.next
}
// Prev returns the previous ring element. r must not be empty.
func (r *ring) Prev() *ring {
if r.next == nil {
return r.init()
}
return r.prev
}
// newRing creates a ring of n elements.
func newRing(n int) *ring {
if n <= 0 {
return nil
}
r := new(ring)
p := r
for i := 1; i < n; i++ {
p.next = &ring{prev: p}
p = p.next
}
p.next = r
r.prev = p
return r
}
// Len computes the number of elements in ring r. It executes in time
// proportional to the number of elements.
func (r *ring) Len() int {
n := 0
if r != nil {
n = 1
for p := r.Next(); p != r; p = p.next {
n++
}
}
return n
}
// Do calls function f on each element of the ring, in forward order. The
// behavior of Do is undefined if f changes *r.
func (r *ring) Do(f func(Record)) {
if r != nil {
f(r.Value)
for p := r.Next(); p != r; p = p.next {
f(p.Value)
}
}
}
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