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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: pool.c,v 1.2 2003/10/12 14:44:46 mdw Exp $ |
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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 $ |
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33 | * Revision 1.2 2003/10/12 14:44:46 mdw |
34 | * Various fixes. |
35 | * |
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36 | * Revision 1.1 2000/07/16 12:28:48 mdw |
37 | * Support for resource pools, based on the Apache model. |
38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
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43 | #include "align.h" |
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44 | #include "alloc.h" |
45 | #include "arena.h" |
46 | #include "pool.h" |
47 | |
48 | /*----- Main code ---------------------------------------------------------*/ |
49 | |
50 | /* --- @doalloc@ --- * |
51 | * |
52 | * Arguments: @arena *a@ = pointer to arena to allocate memory from |
53 | * @pool_chunk **cc@ = pointer to chunk list |
54 | * @size_t sz@ = size of memory wanted |
55 | * |
56 | * Returns: Pointer to the allocated block. |
57 | * |
58 | * Use: The basic allocator for resource pools. This is also used |
59 | * during pool creation, hence the slightly bizarre interface. |
60 | */ |
61 | |
62 | static void *doalloc(arena *a, pool_chunk **cc, size_t sz) |
63 | { |
64 | pool_chunk *c; |
65 | void *p; |
66 | size_t csz, ssz; |
67 | |
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68 | /* --- See if there's enough space --- * |
69 | * |
70 | * The chunks are sorted by available space, so if there's not enough space |
71 | * in the first chunk there isn't enough space anywhere. |
72 | */ |
73 | |
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74 | ALIGN(sz); |
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75 | c = *cc; |
76 | if (c && c->left >= sz) { |
77 | p = c->p; |
78 | c->p += sz; |
79 | c->left -= sz; |
80 | *cc = c->next; |
81 | } |
82 | |
83 | /* --- Failed to find anything --- * |
84 | * |
85 | * I must allocate a new block from the arena, then. |
86 | */ |
87 | |
88 | else { |
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89 | ssz = sizeof(pool_chunk); |
90 | ALIGN(ssz); |
91 | csz = (ssz + sz + POOL_CHUNKSZ - 1); csz -= csz % POOL_CHUNKSZ; |
92 | c = x_alloc(a, csz); |
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93 | p = (char *)c + ssz; |
94 | c->p = (char *)p + sz; |
95 | c->left = csz - ssz - sz; |
96 | } |
97 | |
98 | /* --- Move this chunk in the list so that it's sorted --- */ |
99 | |
100 | while (*cc && (*cc)->left > c->left) |
101 | cc = &(*cc)->next; |
102 | c->next = *cc; |
103 | *cc = c; |
104 | |
105 | /* --- Done --- */ |
106 | |
107 | return (p); |
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108 | } |
109 | |
110 | /* --- @pool_alloc@ --- * |
111 | * |
112 | * Arguments: @pool *p@ = pool to allocate from |
113 | * @size_t sz@ = size of block wanted |
114 | * |
115 | * Returns: Pointer to the requested block. |
116 | * |
117 | * Use: Allocates memory from a resource pool. Memory is never freed |
118 | * from pools: it is released when the pool is destroyed. |
119 | */ |
120 | |
121 | void *pool_alloc(pool *p, size_t sz) |
122 | { |
123 | return (doalloc(p->pa, &p->c, sz)); |
124 | } |
125 | |
126 | /* --- @pool_strdup@ --- * |
127 | * |
128 | * Arguments: @pool *p@ = pool to allocate from |
129 | * @const char *s@ = pointer to string |
130 | * |
131 | * Returns: A pointer to a copy of the string. |
132 | * |
133 | * Use: Allocates a copy of a string. |
134 | */ |
135 | |
136 | char *pool_strdup(pool *p, const char *s) |
137 | { |
138 | size_t sz = strlen(s) + 1; |
139 | char *pp = doalloc(p->pa, &p->c, sz); |
140 | memcpy(pp, s, sz); |
141 | return (pp); |
142 | } |
143 | |
144 | /* --- Arena operations --- */ |
145 | |
146 | static void *palloc(arena *a, size_t sz) |
147 | { |
148 | pool *p = (pool *)a; |
149 | return (doalloc(p->pa, &p->c, sz)); |
150 | } |
151 | |
152 | static void pfree(arena *a, void *p) { return; } /* Trivial */ |
153 | |
154 | static arena_ops pool_ops = { palloc, arena_fakerealloc, pfree, 0 }; |
155 | |
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156 | /* --- @pool_init@ --- * |
157 | * |
158 | * Arguments: @pool *p@ = pointer to the pool structure to initialize |
159 | * @arena *a@ = pointer to an arena to allocate memory from |
160 | * |
161 | * Returns: --- |
162 | * |
163 | * Use: Initializes a chunk of memory as a resource pool which is not |
164 | * a child of any other resource pool. |
165 | */ |
166 | |
167 | void pool_init(pool *p, arena *a) |
168 | { |
169 | p->a.ops = &pool_ops; |
170 | p->c = 0; |
171 | p->r = 0; |
172 | p->pa = a; |
173 | } |
174 | |
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175 | /* --- @pool_create@ --- * |
176 | * |
177 | * Arguments: @arena *a@ = pointer to an arena to allocate memory from |
178 | * |
179 | * Returns: A newly created resource pool. |
180 | * |
181 | * Use: Creates a resource pool which is not a child of any other |
182 | * resource pool. |
183 | */ |
184 | |
185 | pool *pool_create(arena *a) |
186 | { |
187 | pool_chunk *c = 0; |
188 | pool *p = doalloc(a, &c, sizeof(pool)); |
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189 | pool_init(p, a); |
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190 | p->c = c; |
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191 | return (p); |
192 | } |
193 | |
194 | /* --- @pool_destroy@ --- * |
195 | * |
196 | * Arguments: @pool *p@ = pointer to pool to destroy |
197 | * |
198 | * Returns: --- |
199 | * |
200 | * Use: Destroys a pool, freeing all of the resources within it. If |
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201 | * this is a pool created by @pool_create@, its memory will be |
202 | * deallocated; if it's a subpool or it was initialized by |
203 | * @pool_init@, it is emptied and can be used again. |
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204 | */ |
205 | |
206 | void pool_destroy(pool *p) |
207 | { |
208 | pool_resource *r, *rr; |
209 | arena *a; |
210 | pool_chunk *c, *cc; |
211 | |
212 | /* --- Dispose of all of the resources --- */ |
213 | |
214 | r = p->r; |
215 | while (r) { |
216 | rr = r->next; |
217 | if (r->destroy) |
218 | r->destroy(r); |
219 | r = rr; |
220 | } |
221 | p->r = 0; |
222 | |
223 | /* --- Free all of the memory --- * |
224 | * |
225 | * Since root pools are allocated in their own memory, this will free the |
226 | * root pool block. Subpools are allocated in their parent's memory, so |
227 | * the pool block itself will be left around. |
228 | */ |
229 | |
230 | a = p->pa; |
231 | c = p->c; |
232 | p->c = 0; |
233 | while (c) { |
234 | cc = c->next; |
235 | x_free(a, c); |
236 | c = cc; |
237 | } |
238 | } |
239 | |
240 | /* --- @pool_add@ --- * |
241 | * |
242 | * Arguments: @pool *p@ = pointer to pool to add the resource to |
243 | * @pool_resource *r@ = pointer to resource block |
244 | * @void (*dfn)(pool_resource *r)@ = destruction function |
245 | * |
246 | * Returns: --- |
247 | * |
248 | * Use: Adds a resource to a pool. |
249 | */ |
250 | |
251 | void pool_add(pool *p, pool_resource *r, void (*dfn)(pool_resource *r)) |
252 | { |
253 | POOL_ADD(p, r, dfn); |
254 | } |
255 | |
256 | /* --- @pool_sub@ --- * |
257 | * |
258 | * Arguments: @pool *p@ = pointer to parent pool |
259 | * |
260 | * Returns: A new child pool of the parent. |
261 | * |
262 | * Use: Creates a subpool. The subpool can either be destroyed on |
263 | * its own, or will be automatically destroyed at the same time |
264 | * as the parent. |
265 | */ |
266 | |
267 | typedef struct subpool { |
268 | pool_resource r; |
269 | pool p; |
270 | } subpool; |
271 | |
272 | static void subpool_destroy(pool_resource *r) |
273 | { |
274 | subpool *p = (subpool *)r; |
275 | pool_destroy(&p->p); |
276 | } |
277 | |
278 | pool *pool_sub(pool *p) |
279 | { |
280 | subpool *pp = pool_alloc(p, sizeof(subpool)); |
281 | POOL_ADD(p, &pp->r, subpool_destroy); |
282 | pp->p.a.ops = &pool_ops; |
283 | pp->p.c = 0; |
284 | pp->p.r = 0; |
285 | pp->p.pa = p->pa; |
286 | return (&pp->p); |
287 | } |
288 | |
289 | /*----- That's all, folks -------------------------------------------------*/ |