]>
jfr.im git - solanum.git/blob - librb/src/balloc.c
2 * ircd-ratbox: A slightly useful ircd.
3 * balloc.c: A block allocator.
5 * Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
6 * Copyright (C) 1996-2002 Hybrid Development Team
7 * Copyright (C) 2002-2006 ircd-ratbox development team
9 * Below are the orignal headers from the old blalloc.c
12 * Owner: Wohali (Joan Touzet)
14 * Modified 2001/11/29 for mmap() support by Aaron Sethman <androsyn@ratbox.org>
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
26 * You should have received a copy of the GNU General Public License
27 * along with this program; if not, write to the Free Software
28 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301
34 * About the block allocator
36 * Basically we have three ways of getting memory off of the operating
37 * system. Below are this list of methods and the order of preference.
39 * 1. mmap() anonymous pages with the MMAP_ANON flag.
40 * 2. mmap() via the /dev/zero trick.
43 * The advantages of 1 and 2 are this. We can munmap() the pages which will
44 * return the pages back to the operating system, thus reducing the size
45 * of the process as the memory is unused. malloc() on many systems just keeps
46 * a heap of memory to itself, which never gets given back to the OS, except on
47 * exit. This of course is bad, if say we have an event that causes us to allocate
48 * say, 200MB of memory, while our normal memory consumption would be 15MB. In the
49 * malloc() case, the amount of memory allocated to our process never goes down, as
50 * malloc() has it locked up in its heap. With the mmap() method, we can munmap()
51 * the block and return it back to the OS, thus causing our memory consumption to go
52 * down after we no longer need it.
57 #include <librb_config.h>
60 static void _rb_bh_fail(const char *reason
, const char *file
, int line
) __attribute__((noreturn
));
62 static uintptr_t offset_pad
;
64 /* information for the root node of the heap */
68 size_t elemSize
; /* Size of each element to be stored */
69 unsigned long elemsPerBlock
; /* Number of elements per block */
70 rb_dlink_list block_list
;
71 rb_dlink_list free_list
;
75 static rb_dlink_list
*heap_lists
;
77 #define rb_bh_fail(x) _rb_bh_fail(x, __FILE__, __LINE__)
80 _rb_bh_fail(const char *reason
, const char *file
, int line
)
82 rb_lib_log("rb_heap_blockheap failure: %s (%s:%d)", reason
, file
, line
);
87 * void rb_init_bh(void)
91 * Side Effects: Initializes the block heap
97 heap_lists
= rb_malloc(sizeof(rb_dlink_list
));
98 offset_pad
= sizeof(void *);
99 /* XXX if you get SIGBUS when trying to use a long long..here is where you need to
103 if((offset_pad
% __alignof__(long long)) != 0)
105 offset_pad
+= __alignof__(long long);
106 offset_pad
&= ~(__alignof__(long long) - 1);
111 /* ************************************************************************ */
112 /* FUNCTION DOCUMENTATION: */
115 /* Creates a new blockheap from which smaller blocks can be allocated. */
116 /* Intended to be used instead of multiple calls to malloc() when */
117 /* performance is an issue. */
119 /* elemsize (IN): Size of the basic element to be stored */
120 /* elemsperblock (IN): Number of elements to be stored in a single block */
121 /* of memory. When the blockheap runs out of free memory, it will */
122 /* allocate elemsize * elemsperblock more. */
124 /* Pointer to new rb_bh, or NULL if unsuccessful */
125 /* ************************************************************************ */
127 rb_bh_create(size_t elemsize
, int elemsperblock
, const char *desc
)
130 lrb_assert(elemsize
> 0 && elemsperblock
> 0);
131 lrb_assert(elemsize
>= sizeof(rb_dlink_node
));
133 /* Catch idiotic requests up front */
134 if((elemsize
== 0) || (elemsperblock
<= 0))
136 rb_bh_fail("Attempting to rb_bh_create idiotic sizes");
139 if(elemsize
< sizeof(rb_dlink_node
))
140 rb_bh_fail("Attempt to rb_bh_create smaller than sizeof(rb_dlink_node)");
142 /* Allocate our new rb_bh */
143 bh
= rb_malloc(sizeof(rb_bh
));
144 bh
->elemSize
= elemsize
;
145 bh
->elemsPerBlock
= elemsperblock
;
147 bh
->desc
= rb_strdup(desc
);
151 rb_bh_fail("bh == NULL when it shouldn't be");
153 rb_dlinkAdd(bh
, &bh
->hlist
, heap_lists
);
157 /* ************************************************************************ */
158 /* FUNCTION DOCUMENTATION: */
161 /* Returns a pointer to a struct within our rb_bh that's free for */
164 /* bh (IN): Pointer to the Blockheap. */
166 /* Pointer to a structure (void *), or NULL if unsuccessful. */
167 /* ************************************************************************ */
170 rb_bh_alloc(rb_bh
*bh
)
172 lrb_assert(bh
!= NULL
);
173 if(rb_unlikely(bh
== NULL
))
175 rb_bh_fail("Cannot allocate if bh == NULL");
178 return (rb_malloc(bh
->elemSize
));
182 /* ************************************************************************ */
183 /* FUNCTION DOCUMENTATION: */
186 /* Returns an element to the free pool, does not free() */
188 /* bh (IN): Pointer to rb_bh containing element */
189 /* ptr (in): Pointer to element to be "freed" */
191 /* 0 if successful, 1 if element not contained within rb_bh. */
192 /* ************************************************************************ */
194 rb_bh_free(rb_bh
*bh
, void *ptr
)
196 lrb_assert(bh
!= NULL
);
197 lrb_assert(ptr
!= NULL
);
199 if(rb_unlikely(bh
== NULL
))
201 rb_lib_log("balloc.c:rb_bhFree() bh == NULL");
205 if(rb_unlikely(ptr
== NULL
))
207 rb_lib_log("balloc.rb_bhFree() ptr == NULL");
216 /* ************************************************************************ */
217 /* FUNCTION DOCUMENTATION: */
220 /* Completely free()s a rb_bh. Use for cleanup. */
222 /* bh (IN): Pointer to the rb_bh to be destroyed. */
224 /* 0 if successful, 1 if bh == NULL */
225 /* ************************************************************************ */
227 rb_bh_destroy(rb_bh
*bh
)
232 rb_dlinkDelete(&bh
->hlist
, heap_lists
);
240 rb_bh_usage(rb_bh
*bh
__attribute__((unused
)), size_t *bused
, size_t *bfree
, size_t *bmemusage
, const char **desc
)
246 if(bmemusage
!= NULL
)
249 *desc
= "no blockheap";
253 rb_bh_usage_all(rb_bh_usage_cb
*cb
, void *data
)
257 size_t used
, freem
, memusage
, heapalloc
;
258 static const char *unnamed
= "(unnamed_heap)";
259 const char *desc
= unnamed
;
264 RB_DLINK_FOREACH(ptr
, heap_lists
->head
)
266 bh
= (rb_bh
*)ptr
->data
;
267 freem
= rb_dlink_list_length(&bh
->free_list
);
268 used
= (rb_dlink_list_length(&bh
->block_list
) * bh
->elemsPerBlock
) - freem
;
269 memusage
= used
* bh
->elemSize
;
270 heapalloc
= (freem
+ used
) * bh
->elemSize
;
273 cb(used
, freem
, memusage
, heapalloc
, desc
, data
);
279 rb_bh_total_usage(size_t *total_alloc
, size_t *total_used
)
282 size_t total_memory
= 0, used_memory
= 0, used
, freem
;
285 RB_DLINK_FOREACH(ptr
, heap_lists
->head
)
287 bh
= (rb_bh
*)ptr
->data
;
288 freem
= rb_dlink_list_length(&bh
->free_list
);
289 used
= (rb_dlink_list_length(&bh
->block_list
) * bh
->elemsPerBlock
) - freem
;
290 used_memory
+= used
* bh
->elemSize
;
291 total_memory
+= (freem
+ used
) * bh
->elemSize
;
294 if(total_alloc
!= NULL
)
295 *total_alloc
= total_memory
;
296 if(total_used
!= NULL
)
297 *total_used
= used_memory
;