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source: vbox/trunk/src/libs/xpcom18a4/nsprpub/lib/ds/plarena.h@ 1

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1/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* ***** BEGIN LICENSE BLOCK *****
3 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4 *
5 * The contents of this file are subject to the Mozilla Public License Version
6 * 1.1 (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 * http://www.mozilla.org/MPL/
9 *
10 * Software distributed under the License is distributed on an "AS IS" basis,
11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12 * for the specific language governing rights and limitations under the
13 * License.
14 *
15 * The Original Code is the Netscape Portable Runtime (NSPR).
16 *
17 * The Initial Developer of the Original Code is Netscape
18 * Communications Corporation. Portions created by Netscape are
19 * Copyright (C) 1998-2000 Netscape Communications Corporation. All
20 * Rights Reserved.
21 *
22 * Contributor(s):
23 *
24 * Alternatively, the contents of this file may be used under the terms of
25 * either the GNU General Public License Version 2 or later (the "GPL"), or
26 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
27 * in which case the provisions of the GPL or the LGPL are applicable instead
28 * of those above. If you wish to allow use of your version of this file only
29 * under the terms of either the GPL or the LGPL, and not to allow others to
30 * use your version of this file under the terms of the MPL, indicate your
31 * decision by deleting the provisions above and replace them with the notice
32 * and other provisions required by the GPL or the LGPL. If you do not delete
33 * the provisions above, a recipient may use your version of this file under
34 * the terms of any one of the MPL, the GPL or the LGPL.
35 *
36 * ***** END LICENSE BLOCK *****
37 */
38
39#ifndef plarena_h___
40#define plarena_h___
41/*
42 * Lifetime-based fast allocation, inspired by much prior art, including
43 * "Fast Allocation and Deallocation of Memory Based on Object Lifetimes"
44 * David R. Hanson, Software -- Practice and Experience, Vol. 20(1).
45 *
46 * Also supports LIFO allocation (PL_ARENA_MARK/PL_ARENA_RELEASE).
47 */
48#include "prtypes.h"
49#include "plarenas.h"
50
51PR_BEGIN_EXTERN_C
52
53typedef struct PLArena PLArena;
54
55struct PLArena {
56 PLArena *next; /* next arena for this lifetime */
57 PRUword base; /* aligned base address, follows this header */
58 PRUword limit; /* one beyond last byte in arena */
59 PRUword avail; /* points to next available byte */
60};
61
62#ifdef PL_ARENAMETER
63typedef struct PLArenaStats PLArenaStats;
64
65struct PLArenaStats {
66 PLArenaStats *next; /* next in arenaStats list */
67 char *name; /* name for debugging */
68 PRUint32 narenas; /* number of arenas in pool */
69 PRUint32 nallocs; /* number of PL_ARENA_ALLOCATE() calls */
70 PRUint32 nreclaims; /* number of reclaims from freeArenas */
71 PRUint32 nmallocs; /* number of malloc() calls */
72 PRUint32 ndeallocs; /* number of lifetime deallocations */
73 PRUint32 ngrows; /* number of PL_ARENA_GROW() calls */
74 PRUint32 ninplace; /* number of in-place growths */
75 PRUint32 nreleases; /* number of PL_ARENA_RELEASE() calls */
76 PRUint32 nfastrels; /* number of "fast path" releases */
77 PRUint32 nbytes; /* total bytes allocated */
78 PRUint32 maxalloc; /* maximum allocation size in bytes */
79 PRFloat64 variance; /* size variance accumulator */
80};
81#endif
82
83struct PLArenaPool {
84 PLArena first; /* first arena in pool list */
85 PLArena *current; /* arena from which to allocate space */
86 PRUint32 arenasize; /* net exact size of a new arena */
87 PRUword mask; /* alignment mask (power-of-2 - 1) */
88#ifdef PL_ARENAMETER
89 PLArenaStats stats;
90#endif
91};
92
93/*
94 * If the including .c file uses only one power-of-2 alignment, it may define
95 * PL_ARENA_CONST_ALIGN_MASK to the alignment mask and save a few instructions
96 * per ALLOCATE and GROW.
97 */
98#ifdef PL_ARENA_CONST_ALIGN_MASK
99#define PL_ARENA_ALIGN(pool, n) (((PRUword)(n) + PL_ARENA_CONST_ALIGN_MASK) \
100 & ~PL_ARENA_CONST_ALIGN_MASK)
101
102#define PL_INIT_ARENA_POOL(pool, name, size) \
103 PL_InitArenaPool(pool, name, size, PL_ARENA_CONST_ALIGN_MASK + 1)
104#else
105#define PL_ARENA_ALIGN(pool, n) (((PRUword)(n) + (pool)->mask) & ~(pool)->mask)
106#endif
107
108#define PL_ARENA_ALLOCATE(p, pool, nb) \
109 PR_BEGIN_MACRO \
110 PLArena *_a = (pool)->current; \
111 PRUint32 _nb = PL_ARENA_ALIGN(pool, nb); \
112 PRUword _p = _a->avail; \
113 PRUword _q = _p + _nb; \
114 if (_q > _a->limit) \
115 _p = (PRUword)PL_ArenaAllocate(pool, _nb); \
116 else \
117 _a->avail = _q; \
118 p = (void *)_p; \
119 PL_ArenaCountAllocation(pool, nb); \
120 PR_END_MACRO
121
122#define PL_ARENA_GROW(p, pool, size, incr) \
123 PR_BEGIN_MACRO \
124 PLArena *_a = (pool)->current; \
125 PRUint32 _incr = PL_ARENA_ALIGN(pool, incr); \
126 PRUword _p = _a->avail; \
127 PRUword _q = _p + _incr; \
128 if (_p == (PRUword)(p) + PL_ARENA_ALIGN(pool, size) && \
129 _q <= _a->limit) { \
130 _a->avail = _q; \
131 PL_ArenaCountInplaceGrowth(pool, size, incr); \
132 } else { \
133 p = PL_ArenaGrow(pool, p, size, incr); \
134 } \
135 PL_ArenaCountGrowth(pool, size, incr); \
136 PR_END_MACRO
137
138#define PL_ARENA_MARK(pool) ((void *) (pool)->current->avail)
139#define PR_UPTRDIFF(p,q) ((PRUword)(p) - (PRUword)(q))
140
141#ifdef DEBUG
142#define PL_FREE_PATTERN 0xDA
143#define PL_CLEAR_UNUSED(a) (PR_ASSERT((a)->avail <= (a)->limit), \
144 memset((void*)(a)->avail, PL_FREE_PATTERN, \
145 (a)->limit - (a)->avail))
146#define PL_CLEAR_ARENA(a) memset((void*)(a), PL_FREE_PATTERN, \
147 (a)->limit - (PRUword)(a))
148#else
149#define PL_CLEAR_UNUSED(a)
150#define PL_CLEAR_ARENA(a)
151#endif
152
153#define PL_ARENA_RELEASE(pool, mark) \
154 PR_BEGIN_MACRO \
155 char *_m = (char *)(mark); \
156 PLArena *_a = (pool)->current; \
157 if (PR_UPTRDIFF(_m, _a->base) <= PR_UPTRDIFF(_a->avail, _a->base)) { \
158 _a->avail = (PRUword)PL_ARENA_ALIGN(pool, _m); \
159 PL_CLEAR_UNUSED(_a); \
160 PL_ArenaCountRetract(pool, _m); \
161 } else { \
162 PL_ArenaRelease(pool, _m); \
163 } \
164 PL_ArenaCountRelease(pool, _m); \
165 PR_END_MACRO
166
167#ifdef PL_ARENAMETER
168#define PL_COUNT_ARENA(pool,op) ((pool)->stats.narenas op)
169#else
170#define PL_COUNT_ARENA(pool,op)
171#endif
172
173#define PL_ARENA_DESTROY(pool, a, pnext) \
174 PR_BEGIN_MACRO \
175 PL_COUNT_ARENA(pool,--); \
176 if ((pool)->current == (a)) (pool)->current = &(pool)->first; \
177 *(pnext) = (a)->next; \
178 PL_CLEAR_ARENA(a); \
179 free(a); \
180 (a) = 0; \
181 PR_END_MACRO
182
183#ifdef PL_ARENAMETER
184
185#include <stdio.h>
186
187PR_EXTERN(void) PL_ArenaCountAllocation(PLArenaPool *pool, PRUint32 nb);
188
189PR_EXTERN(void) PL_ArenaCountInplaceGrowth(
190 PLArenaPool *pool, PRUint32 size, PRUint32 incr);
191
192PR_EXTERN(void) PL_ArenaCountGrowth(
193 PLArenaPool *pool, PRUint32 size, PRUint32 incr);
194
195PR_EXTERN(void) PL_ArenaCountRelease(PLArenaPool *pool, char *mark);
196
197PR_EXTERN(void) PL_ArenaCountRetract(PLArenaPool *pool, char *mark);
198
199PR_EXTERN(void) PL_DumpArenaStats(FILE *fp);
200
201#else /* !PL_ARENAMETER */
202
203#define PL_ArenaCountAllocation(ap, nb) /* nothing */
204#define PL_ArenaCountInplaceGrowth(ap, size, incr) /* nothing */
205#define PL_ArenaCountGrowth(ap, size, incr) /* nothing */
206#define PL_ArenaCountRelease(ap, mark) /* nothing */
207#define PL_ArenaCountRetract(ap, mark) /* nothing */
208
209#endif /* !PL_ARENAMETER */
210
211PR_END_EXTERN_C
212
213#endif /* plarena_h___ */
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