blob: 204eededf28e2f1a05cfe7a1032998534bd3c0d6 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
package futex
// ElementMapper provides an identity mapping by default.
//
// This can be replaced to provide a struct that maps elements to linker
// objects, if they are not the same. An ElementMapper is not typically
// required if: Linker is left as is, Element is left as is, or Linker and
// Element are the same type.
type waiterElementMapper struct{}
// linkerFor maps an Element to a Linker.
//
// This default implementation should be inlined.
//
//go:nosplit
func (waiterElementMapper) linkerFor(elem *Waiter) *Waiter { return elem }
// List is an intrusive list. Entries can be added to or removed from the list
// in O(1) time and with no additional memory allocations.
//
// The zero value for List is an empty list ready to use.
//
// To iterate over a list (where l is a List):
// for e := l.Front(); e != nil; e = e.Next() {
// // do something with e.
// }
//
// +stateify savable
type waiterList struct {
head *Waiter
tail *Waiter
}
// Reset resets list l to the empty state.
func (l *waiterList) Reset() {
l.head = nil
l.tail = nil
}
// Empty returns true iff the list is empty.
func (l *waiterList) Empty() bool {
return l.head == nil
}
// Front returns the first element of list l or nil.
func (l *waiterList) Front() *Waiter {
return l.head
}
// Back returns the last element of list l or nil.
func (l *waiterList) Back() *Waiter {
return l.tail
}
// PushFront inserts the element e at the front of list l.
func (l *waiterList) PushFront(e *Waiter) {
linker := waiterElementMapper{}.linkerFor(e)
linker.SetNext(l.head)
linker.SetPrev(nil)
if l.head != nil {
waiterElementMapper{}.linkerFor(l.head).SetPrev(e)
} else {
l.tail = e
}
l.head = e
}
// PushBack inserts the element e at the back of list l.
func (l *waiterList) PushBack(e *Waiter) {
linker := waiterElementMapper{}.linkerFor(e)
linker.SetNext(nil)
linker.SetPrev(l.tail)
if l.tail != nil {
waiterElementMapper{}.linkerFor(l.tail).SetNext(e)
} else {
l.head = e
}
l.tail = e
}
// PushBackList inserts list m at the end of list l, emptying m.
func (l *waiterList) PushBackList(m *waiterList) {
if l.head == nil {
l.head = m.head
l.tail = m.tail
} else if m.head != nil {
waiterElementMapper{}.linkerFor(l.tail).SetNext(m.head)
waiterElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
l.tail = m.tail
}
m.head = nil
m.tail = nil
}
// InsertAfter inserts e after b.
func (l *waiterList) InsertAfter(b, e *Waiter) {
bLinker := waiterElementMapper{}.linkerFor(b)
eLinker := waiterElementMapper{}.linkerFor(e)
a := bLinker.Next()
eLinker.SetNext(a)
eLinker.SetPrev(b)
bLinker.SetNext(e)
if a != nil {
waiterElementMapper{}.linkerFor(a).SetPrev(e)
} else {
l.tail = e
}
}
// InsertBefore inserts e before a.
func (l *waiterList) InsertBefore(a, e *Waiter) {
aLinker := waiterElementMapper{}.linkerFor(a)
eLinker := waiterElementMapper{}.linkerFor(e)
b := aLinker.Prev()
eLinker.SetNext(a)
eLinker.SetPrev(b)
aLinker.SetPrev(e)
if b != nil {
waiterElementMapper{}.linkerFor(b).SetNext(e)
} else {
l.head = e
}
}
// Remove removes e from l.
func (l *waiterList) Remove(e *Waiter) {
linker := waiterElementMapper{}.linkerFor(e)
prev := linker.Prev()
next := linker.Next()
if prev != nil {
waiterElementMapper{}.linkerFor(prev).SetNext(next)
} else {
l.head = next
}
if next != nil {
waiterElementMapper{}.linkerFor(next).SetPrev(prev)
} else {
l.tail = prev
}
linker.SetNext(nil)
linker.SetPrev(nil)
}
// Entry is a default implementation of Linker. Users can add anonymous fields
// of this type to their structs to make them automatically implement the
// methods needed by List.
//
// +stateify savable
type waiterEntry struct {
next *Waiter
prev *Waiter
}
// Next returns the entry that follows e in the list.
func (e *waiterEntry) Next() *Waiter {
return e.next
}
// Prev returns the entry that precedes e in the list.
func (e *waiterEntry) Prev() *Waiter {
return e.prev
}
// SetNext assigns 'entry' as the entry that follows e in the list.
func (e *waiterEntry) SetNext(elem *Waiter) {
e.next = elem
}
// SetPrev assigns 'entry' as the entry that precedes e in the list.
func (e *waiterEntry) SetPrev(elem *Waiter) {
e.prev = elem
}
|
