-
Notifications
You must be signed in to change notification settings - Fork 0
/
list_cr_lfrc.c
187 lines (162 loc) · 4.68 KB
/
list_cr_lfrc.c
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
187
/*
* Concurrently-readable linked list using LFRC.
*
* Parts copied from:
* P. E. McKenney. "RCU vs. Locking Performance on Different CPUs".
* linux.conf.au, Adelaide, Australia: January 2004.
*
* URL: http://www.rdrop.com/users/paulmck/rclock/lockperf.2004.01.17a.pdf
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* Copyright (c) IBM Corporation.
* Copyright (c) Thomas E. Hart.
*/
#include <stdio.h>
#include <pthread.h>
#include "spinlock.h"
#include "lfrc.h"
#include "allocator.h"
#include "util.h"
#include "backoff.h"
#include "test.h"
#include <stdio.h>
/* We need to maintain pointers to "prev" and "cur" for reference counting
* purposes, but "prev" is a node**, not a node*, which makes things
* difficult, and we need these to be visible from multiple functions.
*
* Solve this problem by having an array of refs here, similar to the
* hazard pointer array.
*
* Again, array of size 3 with fork(). :p
*/
node_t *refs[3];
/* Helper function. */
static inline void release_temp_refs(unsigned long myTID)
{
lfrc_refcnt_dec(refs[0]);
lfrc_refcnt_dec(refs[1]);
lfrc_refcnt_dec(refs[2]);
refs[0] = refs[1] = refs[2] = NULL;
}
struct list {
node_t *list_head;
spinlock_t list_lock;
};
void list_init(struct list **l)
{
*l = (struct list*)mapmem(sizeof(struct list));
(*l)->list_head = (void*)0;
(*l)->list_lock = SPIN_LOCK_UNLOCKED;
}
void list_destroy(struct list **l)
{
free(*l);
}
int search(struct list *l, long key)
{
node_t **tmp;
node_t **prev, *cur, *next;
node_t **ref0, **ref1, **ref2;
unsigned long myTID = getTID();
int retval;
ref0 = &refs[0];
ref1 = &refs[1];
ref2 = &refs[2];
try_again:
*ref0 = *ref1 = *ref2 = NULL;
prev = &l->list_head;
cur = safe_read(prev);
*ref2 = cur;
for (; cur != NULL; cur = next) {
/* Done with the old *ref0. */
next = safe_read(&cur->next);
lfrc_refcnt_dec(*ref0);
*ref0 = next;
if (*prev != cur) {
release_temp_refs(myTID);
goto try_again;
}
if (cur->key >= key) {
retval = (cur->key == key);
release_temp_refs(myTID);
return retval;
}
prev = &cur->next;
/* Pull the same trick we use with the hazard pointers. */
tmp = ref1;
ref1 = ref2;
ref2 = ref0;
ref0 = tmp;
}
release_temp_refs(myTID);
return (0);
}
/* NB: This a a helper function called with the list lock held. */
int find(node_t **head, long key, unsigned long myTID)
{
node_t **prev, *cur;
prev = head;
for (cur = *prev; cur != NULL; cur = cur->next) {
if (cur->key >= key) {
this_thread()->prev = prev;
this_thread()->cur = cur;
return (cur->key == key);
}
prev = &cur->next;
}
/* Didn't find the key. */
this_thread()->prev = prev;
this_thread()->cur = cur;
return 0;
}
int delete(struct list *l, long key)
{
int myTID = getTID();
spin_lock(&l->list_lock);
if (!find(&l->list_head, key, myTID)) {
spin_unlock(&l->list_lock);
return 0;
}
/* Logically delete cur. */
/* We'll be setting a new reference to cur->next if we're successful,
* but also getting rid of cur's reference to it. We must
* increment the reference count for the new reference, since the
* old one will be automatically taken away.
*/
lfrc_refcnt_inc(this_thread()->cur->next);
*this_thread()->prev = this_thread()->cur->next;
lfrc_refcnt_dec(this_thread()->cur);
spin_unlock(&l->list_lock);
return 1;
}
int insert(struct list *l, long key)
{
int myTID = getTID();
node_t *n = new_node();
spin_lock(&l->list_lock);
if (find(&l->list_head, key, myTID)) {
spin_unlock(&l->list_lock);
n->next = NULL;
lfrc_refcnt_dec(n);
return (0);
}
n->key = key;
n->next = this_thread()->cur;
write_barrier();
*this_thread()->prev = n;
spin_unlock(&l->list_lock);
return (1);
}