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
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
//
// Copyright 2016 Garrett D'Amore <garrett@damore.org>
//
// This software is supplied under the terms of the MIT License, a
// copy of which should be located in the distribution where this
// file was obtained (LICENSE.txt). A copy of the license may also be
// found online at https://opensource.org/licenses/MIT.
//
#include "core/nng_impl.h"
#include <string.h>
typedef struct {
uint32_t ihe_key;
uint32_t ihe_skips;
void * ihe_val;
} nni_idhash_entry;
struct nni_idhash {
uint32_t ih_cap;
uint32_t ih_count;
uint32_t ih_load;
uint32_t ih_minload; // considers placeholders
uint32_t ih_maxload;
uint32_t ih_walkers;
nni_idhash_entry * ih_entries;
};
int
nni_idhash_create(nni_idhash **hp)
{
nni_idhash *h;
if ((h = NNI_ALLOC_STRUCT(h)) == NULL) {
return (NNG_ENOMEM);
}
h->ih_entries = nni_alloc(8 * sizeof (nni_idhash_entry));
if (h->ih_entries == NULL) {
NNI_FREE_STRUCT(h);
return (NNG_ENOMEM);
}
(void) memset(h->ih_entries, 0, (8 * sizeof (nni_idhash_entry)));
h->ih_count = 0;
h->ih_load = 0;
h->ih_cap = 8;
h->ih_maxload = 5;
h->ih_minload = 0; // never shrink below this
h->ih_walkers = 0;
*hp = h;
return (0);
}
void
nni_idhash_destroy(nni_idhash *h)
{
nni_free(h->ih_entries, h->ih_cap * sizeof (nni_idhash_entry));
NNI_FREE_STRUCT(h);
}
// Inspired by Python dict implementation. This probe will visit every
// cell. We always hash consecutively assigned IDs.
#define NNI_IDHASH_NEXTPROBE(h, j) \
((((j) * 5) + 1) & (h->ih_cap - 1))
int
nni_idhash_find(nni_idhash *h, uint32_t id, void **valp)
{
uint32_t index = id & (h->ih_cap - 1);
for (;;) {
if ((h->ih_entries[index].ihe_val == NULL) &&
(h->ih_entries[index].ihe_skips == 0)) {
return (NNG_ENOENT);
}
if (h->ih_entries[index].ihe_key == id) {
*valp = h->ih_entries[index].ihe_val;
return (0);
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
static int
nni_hash_resize(nni_idhash *h)
{
uint32_t newsize;
uint32_t oldsize;
nni_idhash_entry *newents;
nni_idhash_entry *oldents;
int i;
if ((h->ih_load < h->ih_maxload) && (h->ih_load >= h->ih_minload)) {
// No resize needed.
return (0);
}
if (h->ih_walkers && (h->ih_load < (h->ih_cap-1))) {
// Don't resize when walkers are running. This way
// walk functions can remove hash nodes.
return (0);
}
oldsize = h->ih_cap;
newsize = h->ih_cap;
newsize = 8;
while (newsize < (h->ih_count * 2)) {
newsize *= 2;
}
oldents = h->ih_entries;
newents = nni_alloc(sizeof (nni_idhash_entry) * newsize);
if (newents == NULL) {
return (NNG_ENOMEM);
}
memset(newents, 0, sizeof (nni_idhash_entry) * newsize);
h->ih_entries = newents;
h->ih_cap = newsize;
if (newsize > 8) {
h->ih_minload = newsize / 8;
h->ih_maxload = newsize * 2 / 3;
} else {
h->ih_minload = 0;
h->ih_maxload = 5;
}
for (i = 0; i < oldsize; i++) {
uint32_t index;
if (oldents[i].ihe_val == NULL) {
continue;
}
index = oldents[i].ihe_key & (newsize - 1);
for (;;) {
if (newents[index].ihe_val == NULL) {
h->ih_load++;
newents[index].ihe_val = oldents[i].ihe_val;
newents[index].ihe_key = oldents[i].ihe_key;
break;
}
newents[index].ihe_skips++;
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
nni_free(oldents, sizeof (nni_idhash_entry) * oldsize);
return (0);
}
int
nni_idhash_remove(nni_idhash *h, uint32_t id)
{
int rv;
void *val;
uint32_t index;
// First check that it is in the table. This may double the
// lookup time, but it means that if we get past this then we KNOW
// we are going to delete an element.
if ((rv = nni_idhash_find(h, id, &val)) != 0) {
return (rv);
}
index = id & (h->ih_cap - 1);
for (;;) {
nni_idhash_entry *ent = &h->ih_entries[index];
if (ent->ihe_key == id) {
ent->ihe_val = NULL;
if (ent->ihe_skips == 0) {
h->ih_load--;
}
h->ih_count--;
break;
}
if (ent->ihe_skips < 1) {
nni_panic("Skips should be nonzero!");
}
ent->ihe_skips--;
if ((ent->ihe_skips == 0) && (ent->ihe_val == NULL)) {
h->ih_load--;
}
index = NNI_IDHASH_NEXTPROBE(h, index);
}
// Shrink -- but it's ok if we can't.
(void) nni_hash_resize(h);
return (0);
}
int
nni_idhash_insert(nni_idhash *h, uint32_t id, void *val)
{
uint32_t index;
// Try to resize. If we can't, but we still have room, go ahead
// and store it.
if ((nni_hash_resize(h) != 0) && (h->ih_count >= (h->ih_cap - 1))) {
return (NNG_ENOMEM);
}
index = id & (h->ih_cap - 1);
for (;;) {
nni_idhash_entry *ent = &h->ih_entries[index];
if ((ent->ihe_val == NULL) || (ent->ihe_key == id)) {
if (ent->ihe_val == NULL) {
h->ih_count++;
h->ih_load++;
}
ent->ihe_key = id;
ent->ihe_val = val;
return (0);
}
ent->ihe_skips++;
index = NNI_IDHASH_NEXTPROBE(h, index);
}
}
int
nni_idhash_count(nni_idhash *h, uint32_t *countp)
{
*countp = h->ih_count;
return (0);
}
int
nni_idhash_walk(nni_idhash *h, nni_idhash_walkfn fn, void *arg)
{
int i, rv;
for (i = 0; i < h->ih_cap; i++) {
nni_idhash_entry *ent = &h->ih_entries[i];
if (ent->ihe_val == NULL) {
continue;
}
rv = fn(arg, ent->ihe_key, ent->ihe_val);
if (rv != 0) {
return (rv);
}
}
return (0);
}
|
