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1 | /* -*-c-*- |
2 | * |
3 | * $Id: pool.c,v 1.1 2000/07/16 12:28:48 mdw Exp $ |
4 | * |
5 | * Resource pool handling |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
14 | * mLib is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * mLib is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with mLib; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: pool.c,v $ |
33 | * Revision 1.1 2000/07/16 12:28:48 mdw |
34 | * Support for resource pools, based on the Apache model. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "alloc.h" |
41 | #include "arena.h" |
42 | #include "pool.h" |
43 | |
44 | /*----- Main code ---------------------------------------------------------*/ |
45 | |
46 | /* --- @doalloc@ --- * |
47 | * |
48 | * Arguments: @arena *a@ = pointer to arena to allocate memory from |
49 | * @pool_chunk **cc@ = pointer to chunk list |
50 | * @size_t sz@ = size of memory wanted |
51 | * |
52 | * Returns: Pointer to the allocated block. |
53 | * |
54 | * Use: The basic allocator for resource pools. This is also used |
55 | * during pool creation, hence the slightly bizarre interface. |
56 | */ |
57 | |
58 | static void *doalloc(arena *a, pool_chunk **cc, size_t sz) |
59 | { |
60 | pool_chunk *c; |
61 | void *p; |
62 | size_t csz, ssz; |
63 | |
64 | /* --- Round up the requested size --- * |
65 | * |
66 | * This assumes too much about how various objects are aligned. It could |
67 | * do with improvement some time. This is, I believe, the only |
68 | * nonportability in the code, and it should work on `sane' architectures |
69 | * anyway. |
70 | */ |
71 | |
72 | #define ROUNDUP(sz) ((sz + 15) % 16) |
73 | |
74 | sz = ROUNDUP(sz); |
75 | |
76 | /* --- See if there's enough space --- * |
77 | * |
78 | * The chunks are sorted by available space, so if there's not enough space |
79 | * in the first chunk there isn't enough space anywhere. |
80 | */ |
81 | |
82 | c = *cc; |
83 | if (c && c->left >= sz) { |
84 | p = c->p; |
85 | c->p += sz; |
86 | c->left -= sz; |
87 | *cc = c->next; |
88 | } |
89 | |
90 | /* --- Failed to find anything --- * |
91 | * |
92 | * I must allocate a new block from the arena, then. |
93 | */ |
94 | |
95 | else { |
96 | ssz = ROUNDUP(sizeof(pool_chunk)); |
97 | csz = (ssz + sz + POOL_CHUNKSZ - 1) % POOL_CHUNKSZ; |
98 | p = x_alloc(a, csz); |
99 | p = (char *)c + ssz; |
100 | c->p = (char *)p + sz; |
101 | c->left = csz - ssz - sz; |
102 | } |
103 | |
104 | /* --- Move this chunk in the list so that it's sorted --- */ |
105 | |
106 | while (*cc && (*cc)->left > c->left) |
107 | cc = &(*cc)->next; |
108 | c->next = *cc; |
109 | *cc = c; |
110 | |
111 | /* --- Done --- */ |
112 | |
113 | return (p); |
114 | |
115 | #undef ROUNDUP |
116 | } |
117 | |
118 | /* --- @pool_alloc@ --- * |
119 | * |
120 | * Arguments: @pool *p@ = pool to allocate from |
121 | * @size_t sz@ = size of block wanted |
122 | * |
123 | * Returns: Pointer to the requested block. |
124 | * |
125 | * Use: Allocates memory from a resource pool. Memory is never freed |
126 | * from pools: it is released when the pool is destroyed. |
127 | */ |
128 | |
129 | void *pool_alloc(pool *p, size_t sz) |
130 | { |
131 | return (doalloc(p->pa, &p->c, sz)); |
132 | } |
133 | |
134 | /* --- @pool_strdup@ --- * |
135 | * |
136 | * Arguments: @pool *p@ = pool to allocate from |
137 | * @const char *s@ = pointer to string |
138 | * |
139 | * Returns: A pointer to a copy of the string. |
140 | * |
141 | * Use: Allocates a copy of a string. |
142 | */ |
143 | |
144 | char *pool_strdup(pool *p, const char *s) |
145 | { |
146 | size_t sz = strlen(s) + 1; |
147 | char *pp = doalloc(p->pa, &p->c, sz); |
148 | memcpy(pp, s, sz); |
149 | return (pp); |
150 | } |
151 | |
152 | /* --- Arena operations --- */ |
153 | |
154 | static void *palloc(arena *a, size_t sz) |
155 | { |
156 | pool *p = (pool *)a; |
157 | return (doalloc(p->pa, &p->c, sz)); |
158 | } |
159 | |
160 | static void pfree(arena *a, void *p) { return; } /* Trivial */ |
161 | |
162 | static arena_ops pool_ops = { palloc, arena_fakerealloc, pfree, 0 }; |
163 | |
164 | /* --- @pool_create@ --- * |
165 | * |
166 | * Arguments: @arena *a@ = pointer to an arena to allocate memory from |
167 | * |
168 | * Returns: A newly created resource pool. |
169 | * |
170 | * Use: Creates a resource pool which is not a child of any other |
171 | * resource pool. |
172 | */ |
173 | |
174 | pool *pool_create(arena *a) |
175 | { |
176 | pool_chunk *c = 0; |
177 | pool *p = doalloc(a, &c, sizeof(pool)); |
178 | p->a.ops = &pool_ops; |
179 | p->c = c; |
180 | p->r = 0; |
181 | p->pa = a; |
182 | return (p); |
183 | } |
184 | |
185 | /* --- @pool_destroy@ --- * |
186 | * |
187 | * Arguments: @pool *p@ = pointer to pool to destroy |
188 | * |
189 | * Returns: --- |
190 | * |
191 | * Use: Destroys a pool, freeing all of the resources within it. If |
192 | * this is a root pool, its memory will be deallocated; if it's |
193 | * a subpool, it is emptied and can be used again. |
194 | */ |
195 | |
196 | void pool_destroy(pool *p) |
197 | { |
198 | pool_resource *r, *rr; |
199 | arena *a; |
200 | pool_chunk *c, *cc; |
201 | |
202 | /* --- Dispose of all of the resources --- */ |
203 | |
204 | r = p->r; |
205 | while (r) { |
206 | rr = r->next; |
207 | if (r->destroy) |
208 | r->destroy(r); |
209 | r = rr; |
210 | } |
211 | p->r = 0; |
212 | |
213 | /* --- Free all of the memory --- * |
214 | * |
215 | * Since root pools are allocated in their own memory, this will free the |
216 | * root pool block. Subpools are allocated in their parent's memory, so |
217 | * the pool block itself will be left around. |
218 | */ |
219 | |
220 | a = p->pa; |
221 | c = p->c; |
222 | p->c = 0; |
223 | while (c) { |
224 | cc = c->next; |
225 | x_free(a, c); |
226 | c = cc; |
227 | } |
228 | } |
229 | |
230 | /* --- @pool_add@ --- * |
231 | * |
232 | * Arguments: @pool *p@ = pointer to pool to add the resource to |
233 | * @pool_resource *r@ = pointer to resource block |
234 | * @void (*dfn)(pool_resource *r)@ = destruction function |
235 | * |
236 | * Returns: --- |
237 | * |
238 | * Use: Adds a resource to a pool. |
239 | */ |
240 | |
241 | void pool_add(pool *p, pool_resource *r, void (*dfn)(pool_resource *r)) |
242 | { |
243 | POOL_ADD(p, r, dfn); |
244 | } |
245 | |
246 | /* --- @pool_sub@ --- * |
247 | * |
248 | * Arguments: @pool *p@ = pointer to parent pool |
249 | * |
250 | * Returns: A new child pool of the parent. |
251 | * |
252 | * Use: Creates a subpool. The subpool can either be destroyed on |
253 | * its own, or will be automatically destroyed at the same time |
254 | * as the parent. |
255 | */ |
256 | |
257 | typedef struct subpool { |
258 | pool_resource r; |
259 | pool p; |
260 | } subpool; |
261 | |
262 | static void subpool_destroy(pool_resource *r) |
263 | { |
264 | subpool *p = (subpool *)r; |
265 | pool_destroy(&p->p); |
266 | } |
267 | |
268 | pool *pool_sub(pool *p) |
269 | { |
270 | subpool *pp = pool_alloc(p, sizeof(subpool)); |
271 | POOL_ADD(p, &pp->r, subpool_destroy); |
272 | pp->p.a.ops = &pool_ops; |
273 | pp->p.c = 0; |
274 | pp->p.r = 0; |
275 | pp->p.pa = p->pa; |
276 | return (&pp->p); |
277 | } |
278 | |
279 | /*----- That's all, folks -------------------------------------------------*/ |