1 /*------------------------------------------------------------------------*/ 2 /*--- A simple pool (memory) allocator implementation. m_poolalloc.c --- */ 3 /*------------------------------------------------------------------------*/ 4 /* 5 This file is part of Valgrind, a dynamic binary instrumentation 6 framework. 7 8 Copyright (C) 2011-2017 OpenWorks LLP info (at) open-works.co.uk, 9 Philippe Waroquiers philippe.waroquiers (at) skynet.be 10 11 This program is free software; you can redistribute it and/or 12 modify it under the terms of the GNU General Public License as 13 published by the Free Software Foundation; either version 2 of the 14 License, or (at your option) any later version. 15 16 This program is distributed in the hope that it will be useful, but 17 WITHOUT ANY WARRANTY; without even the implied warranty of 18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 19 General Public License for more details. 20 21 You should have received a copy of the GNU General Public License 22 along with this program; if not, write to the Free Software 23 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 24 02111-1307, USA. 25 26 The GNU General Public License is contained in the file COPYING. 27 */ 28 29 #include "pub_core_basics.h" 30 #include "pub_core_libcbase.h" 31 #include "pub_core_libcassert.h" 32 #include "pub_core_xarray.h" 33 #include "pub_core_poolalloc.h" /* self */ 34 35 struct _PoolAlloc { 36 UWord nrRef; /* nr reference to this pool allocator */ 37 UWord elemSzB; /* element size */ 38 UWord nPerPool; /* # elems per pool */ 39 Alloc_Fn_t alloc_fn; /* pool allocator */ 40 const HChar* cc; /* pool allocator's cost centre */ 41 Free_Fn_t free_fn; /* pool allocator's free-er */ 42 /* XArray of void* (pointers to pools). The pools themselves. 43 Each element is a pointer to a block of size (elemSzB * 44 nPerPool) bytes. */ 45 XArray* pools; 46 /* next free element. Is a pointer to an element in one of the 47 pools pointed to by .pools */ 48 void* nextFree; 49 }; 50 51 PoolAlloc* VG_(newPA) ( UWord elemSzB, 52 UWord nPerPool, 53 Alloc_Fn_t alloc_fn, 54 const HChar* cc, 55 Free_Fn_t free_fn ) 56 { 57 PoolAlloc* pa; 58 vg_assert(0 == (elemSzB % sizeof(UWord))); 59 vg_assert(elemSzB >= sizeof(UWord)); 60 vg_assert(nPerPool >= 100); /* let's say */ 61 vg_assert(alloc_fn); 62 vg_assert(cc); 63 vg_assert(free_fn); 64 pa = alloc_fn(cc, sizeof(*pa)); 65 VG_(memset)(pa, 0, sizeof(*pa)); 66 pa->nrRef = 0; 67 pa->elemSzB = elemSzB; 68 pa->nPerPool = nPerPool; 69 pa->pools = NULL; 70 pa->alloc_fn = alloc_fn; 71 pa->cc = cc; 72 pa->free_fn = free_fn; 73 pa->pools = VG_(newXA)( alloc_fn, cc, free_fn, sizeof(void*) ); 74 pa->nextFree = NULL; 75 76 return pa; 77 } 78 79 void VG_(deletePA) ( PoolAlloc* pa) 80 { 81 Word i; 82 vg_assert(pa->nrRef == 0); 83 for (i = 0; i < VG_(sizeXA) (pa->pools); i++) 84 pa->free_fn (*(UWord **)VG_(indexXA) ( pa->pools, i )); 85 VG_(deleteXA) (pa->pools); 86 pa->free_fn (pa); 87 } 88 89 /* The freelist is empty. Allocate a new pool and put all the new 90 elements in it onto the freelist. */ 91 __attribute__((noinline)) 92 static void pal_add_new_pool ( PoolAlloc* pa ) 93 { 94 Word i; 95 UWord* pool; 96 vg_assert(pa); 97 vg_assert(pa->nextFree == NULL); 98 pool = pa->alloc_fn( pa->cc, pa->elemSzB * pa->nPerPool ); 99 /* extend the freelist through the new pool. Place the freelist 100 pointer in the first word of each element. That's why the 101 element size must be at least one word. */ 102 for (i = pa->nPerPool-1; i >= 0; i--) { 103 UChar* elemC = ((UChar*)pool) + i * pa->elemSzB; 104 UWord* elem = (UWord*)elemC; 105 vg_assert(0 == (((UWord)elem) % sizeof(UWord))); 106 *elem = (UWord)pa->nextFree; 107 pa->nextFree = elem; 108 } 109 /* and add to our collection of pools */ 110 VG_(addToXA)( pa->pools, &pool ); 111 } 112 113 UWord VG_(sizePA) ( PoolAlloc* pa) 114 { 115 vg_assert(pa); 116 return pa->nPerPool * VG_(sizeXA) (pa->pools); 117 } 118 119 void* VG_(allocEltPA) ( PoolAlloc* pa) 120 { 121 UWord* elem; 122 if (UNLIKELY(pa->nextFree == NULL)) { 123 pal_add_new_pool(pa); 124 } 125 elem = pa->nextFree; 126 pa->nextFree = (void*)*elem; 127 *elem = 0; /* unnecessary, but just to be on the safe side */ 128 return elem; 129 } 130 131 void VG_(freeEltPA) ( PoolAlloc* pa, void* p) 132 { 133 UWord* elem = (UWord*)p; 134 *elem = (UWord)pa->nextFree; 135 pa->nextFree = elem; 136 } 137 138 139 void VG_(addRefPA) ( PoolAlloc* pa) 140 { 141 pa->nrRef++; 142 } 143 144 UWord VG_(releasePA)(PoolAlloc* pa) 145 { 146 UWord nrRef; 147 148 vg_assert(pa->nrRef > 0); 149 nrRef = --pa->nrRef; 150 if (nrRef == 0) 151 VG_(deletePA)(pa); 152 return nrRef; 153 } 154