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
|
// Copyright 2010 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.
#include "runtime.h"
#include "arch_GOARCH.h"
#include "malloc.h"
#include "type.h"
enum { debug = 0 };
typedef struct Fin Fin;
struct Fin
{
FuncVal *fn;
uintptr nret;
Type *fint;
PtrType *ot;
};
// Finalizer hash table. Direct hash, linear scan, at most 3/4 full.
// Table size is power of 3 so that hash can be key % max.
// Key[i] == (void*)-1 denotes free but formerly occupied entry
// (doesn't stop the linear scan).
// Key and val are separate tables because the garbage collector
// must be instructed to ignore the pointers in key but follow the
// pointers in val.
typedef struct Fintab Fintab;
struct Fintab
{
Lock;
void **key;
Fin *val;
int32 nkey; // number of non-nil entries in key
int32 ndead; // number of dead (-1) entries in key
int32 max; // size of key, val allocations
};
#define TABSZ 17
#define TAB(p) (&fintab[((uintptr)(p)>>3)%TABSZ])
static struct {
Fintab;
uint8 pad[CacheLineSize - sizeof(Fintab)];
} fintab[TABSZ];
static void
addfintab(Fintab *t, void *k, FuncVal *fn, uintptr nret, Type *fint, PtrType *ot)
{
int32 i, j;
i = (uintptr)k % (uintptr)t->max;
for(j=0; j<t->max; j++) {
if(t->key[i] == nil) {
t->nkey++;
goto ret;
}
if(t->key[i] == (void*)-1) {
t->ndead--;
goto ret;
}
if(++i == t->max)
i = 0;
}
// cannot happen - table is known to be non-full
runtime·throw("finalizer table inconsistent");
ret:
t->key[i] = k;
t->val[i].fn = fn;
t->val[i].nret = nret;
t->val[i].fint = fint;
t->val[i].ot = ot;
}
static bool
lookfintab(Fintab *t, void *k, bool del, Fin *f)
{
int32 i, j;
if(t->max == 0)
return false;
i = (uintptr)k % (uintptr)t->max;
for(j=0; j<t->max; j++) {
if(t->key[i] == nil)
return false;
if(t->key[i] == k) {
if(f)
*f = t->val[i];
if(del) {
t->key[i] = (void*)-1;
t->val[i].fn = nil;
t->val[i].nret = 0;
t->val[i].ot = nil;
t->ndead++;
}
return true;
}
if(++i == t->max)
i = 0;
}
// cannot happen - table is known to be non-full
runtime·throw("finalizer table inconsistent");
return false;
}
static void
resizefintab(Fintab *tab)
{
Fintab newtab;
void *k;
int32 i;
runtime·memclr((byte*)&newtab, sizeof newtab);
newtab.max = tab->max;
if(newtab.max == 0)
newtab.max = 3*3*3;
else if(tab->ndead < tab->nkey/2) {
// grow table if not many dead values.
// otherwise just rehash into table of same size.
newtab.max *= 3;
}
newtab.key = runtime·mallocgc(newtab.max*sizeof newtab.key[0], 0, FlagNoInvokeGC|FlagNoScan);
newtab.val = runtime·mallocgc(newtab.max*sizeof newtab.val[0], 0, FlagNoInvokeGC);
for(i=0; i<tab->max; i++) {
k = tab->key[i];
if(k != nil && k != (void*)-1)
addfintab(&newtab, k, tab->val[i].fn, tab->val[i].nret, tab->val[i].fint, tab->val[i].ot);
}
runtime·free(tab->key);
runtime·free(tab->val);
tab->key = newtab.key;
tab->val = newtab.val;
tab->nkey = newtab.nkey;
tab->ndead = newtab.ndead;
tab->max = newtab.max;
}
bool
runtime·addfinalizer(void *p, FuncVal *f, uintptr nret, Type *fint, PtrType *ot)
{
Fintab *tab;
byte *base;
if(debug) {
if(!runtime·mlookup(p, &base, nil, nil) || p != base)
runtime·throw("addfinalizer on invalid pointer");
}
tab = TAB(p);
runtime·lock(tab);
if(f == nil) {
lookfintab(tab, p, true, nil);
runtime·unlock(tab);
return true;
}
if(lookfintab(tab, p, false, nil)) {
runtime·unlock(tab);
return false;
}
if(tab->nkey >= tab->max/2+tab->max/4) {
// keep table at most 3/4 full:
// allocate new table and rehash.
resizefintab(tab);
}
addfintab(tab, p, f, nret, fint, ot);
runtime·setblockspecial(p, true);
runtime·unlock(tab);
return true;
}
// get finalizer; if del, delete finalizer.
// caller is responsible for updating RefHasFinalizer (special) bit.
bool
runtime·getfinalizer(void *p, bool del, FuncVal **fn, uintptr *nret, Type **fint, PtrType **ot)
{
Fintab *tab;
bool res;
Fin f;
tab = TAB(p);
runtime·lock(tab);
res = lookfintab(tab, p, del, &f);
runtime·unlock(tab);
if(res==false)
return false;
*fn = f.fn;
*nret = f.nret;
*fint = f.fint;
*ot = f.ot;
return true;
}
void
runtime·walkfintab(void (*fn)(void*))
{
void **key;
void **ekey;
int32 i;
for(i=0; i<TABSZ; i++) {
runtime·lock(&fintab[i]);
key = fintab[i].key;
ekey = key + fintab[i].max;
for(; key < ekey; key++)
if(*key != nil && *key != ((void*)-1))
fn(*key);
runtime·unlock(&fintab[i]);
}
}
|
