1 /* libunwind - a platform-independent unwind library 2 Copyright (C) 2002-2003 Hewlett-Packard Co 3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com> 4 5 This file is part of libunwind. 6 7 Permission is hereby granted, free of charge, to any person obtaining 8 a copy of this software and associated documentation files (the 9 "Software"), to deal in the Software without restriction, including 10 without limitation the rights to use, copy, modify, merge, publish, 11 distribute, sublicense, and/or sell copies of the Software, and to 12 permit persons to whom the Software is furnished to do so, subject to 13 the following conditions: 14 15 The above copyright notice and this permission notice shall be 16 included in all copies or substantial portions of the Software. 17 18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 25 26 #ifndef mempool_h 27 #define mempool_h 28 29 /* Memory pools provide simple memory management of fixed-size 30 objects. Memory pools are used for two purposes: 31 32 o To ensure a stack can be unwound even when a process 33 is out of memory. 34 35 o To ensure a stack can be unwound at any time in a 36 multi-threaded process (e.g., even at a time when the normal 37 malloc-lock is taken, possibly by the very thread that is 38 being unwind). 39 40 41 To achieve the second objective, memory pools allocate memory 42 directly via mmap() system call (or an equivalent facility). 43 44 The first objective is accomplished by reserving memory ahead of 45 time. Since the memory requirements of stack unwinding generally 46 depends on the complexity of the procedures being unwind, there is 47 no absolute guarantee that unwinding will always work, but in 48 practice, this should not be a serious problem. */ 49 50 #include <sys/types.h> 51 52 #include "libunwind_i.h" 53 54 #define sos_alloc(s) UNWI_ARCH_OBJ(_sos_alloc)(s) 55 #define mempool_init(p,s,r) UNWI_ARCH_OBJ(_mempool_init)(p,s,r) 56 #define mempool_alloc(p) UNWI_ARCH_OBJ(_mempool_alloc)(p) 57 #define mempool_free(p,o) UNWI_ARCH_OBJ(_mempool_free)(p,o) 58 59 /* The mempool structure should be treated as an opaque object. It's 60 declared here only to enable static allocation of mempools. */ 61 struct mempool 62 { 63 pthread_mutex_t lock; 64 size_t obj_size; /* object size (rounded up for alignment) */ 65 size_t chunk_size; /* allocation granularity */ 66 unsigned int reserve; /* minimum (desired) size of the free-list */ 67 unsigned int num_free; /* number of objects on the free-list */ 68 struct object 69 { 70 struct object *next; 71 } 72 *free_list; 73 }; 74 75 /* Emergency allocation for one-time stuff that doesn't fit the memory 76 pool model. A limited amount of memory is available in this 77 fashion and once allocated, there is no way to free it. */ 78 extern void *sos_alloc (size_t size); 79 80 /* Initialize POOL for an object size of OBJECT_SIZE bytes. RESERVE 81 is the number of objects that should be reserved for use under 82 tight memory situations. If it is zero, mempool attempts to pick a 83 reasonable default value. */ 84 extern void mempool_init (struct mempool *pool, 85 size_t obj_size, size_t reserve); 86 extern void *mempool_alloc (struct mempool *pool); 87 extern void mempool_free (struct mempool *pool, void *object); 88 89 #endif /* mempool_h */ 90