diff options
Diffstat (limited to 'db2/common/db_salloc.c')
-rw-r--r-- | db2/common/db_salloc.c | 302 |
1 files changed, 0 insertions, 302 deletions
diff --git a/db2/common/db_salloc.c b/db2/common/db_salloc.c deleted file mode 100644 index d58b79f3c4..0000000000 --- a/db2/common/db_salloc.c +++ /dev/null @@ -1,302 +0,0 @@ -/*- - * See the file LICENSE for redistribution information. - * - * Copyright (c) 1996, 1997, 1998 - * Sleepycat Software. All rights reserved. - */ - -#include "config.h" - -#ifndef lint -static const char sccsid[] = "@(#)db_salloc.c 10.14 (Sleepycat) 11/16/98"; -#endif /* not lint */ - -#ifndef NO_SYSTEM_INCLUDES -#include <sys/types.h> - -#include <errno.h> -#include <string.h> -#endif - -#include "db_int.h" -#include "shqueue.h" -#include "common_ext.h" - -/* - * Implement shared memory region allocation, using simple first-fit algorithm. - * The model is that we take a "chunk" of shared memory store and begin carving - * it up into areas, similarly to how malloc works. We do coalescing on free. - * - * The "len" field in the __data struct contains the length of the free region - * (less the size_t bytes that holds the length). We use the address provided - * by the caller to find this length, which allows us to free a chunk without - * requiring that the caller pass in the length of the chunk they're freeing. - */ -SH_LIST_HEAD(__head); -struct __data { - size_t len; - SH_LIST_ENTRY links; -}; - -/* - * __db_shalloc_init -- - * Initialize the area as one large chunk. - * - * PUBLIC: void __db_shalloc_init __P((void *, size_t)); - */ -void -__db_shalloc_init(area, size) - void *area; - size_t size; -{ - struct __data *elp; - struct __head *hp; - - hp = area; - SH_LIST_INIT(hp); - - elp = (struct __data *)(hp + 1); - elp->len = size - sizeof(struct __head) - sizeof(elp->len); - SH_LIST_INSERT_HEAD(hp, elp, links, __data); -} - -/* - * __db_shalloc -- - * Allocate some space from the shared region. - * - * PUBLIC: int __db_shalloc __P((void *, size_t, size_t, void *)); - */ -int -__db_shalloc(p, len, align, retp) - void *p, *retp; - size_t len, align; -{ - struct __data *elp; - size_t *sp; - void *rp; - - /* - * We never allocate less than the size of a struct __data, align - * to less than a size_t boundary, or align to something that's not - * a multiple of a size_t. - */ - if (len < sizeof(struct __data)) - len = sizeof(struct __data); - align = align <= sizeof(size_t) ? - sizeof(size_t) : ALIGN(align, sizeof(size_t)); - - /* Walk the list, looking for a slot. */ - for (elp = SH_LIST_FIRST((struct __head *)p, __data); - elp != NULL; - elp = SH_LIST_NEXT(elp, links, __data)) { - /* - * Calculate the value of the returned pointer if we were to - * use this chunk. - * + Find the end of the chunk. - * + Subtract the memory the user wants. - * + Find the closest previous correctly-aligned address. - */ - rp = (u_int8_t *)elp + sizeof(size_t) + elp->len; - rp = (u_int8_t *)rp - len; - rp = (u_int8_t *)((ALIGNTYPE)rp & ~(align - 1)); - - /* - * Rp may now point before elp->links, in which case the chunk - * was too small, and we have to try again. - */ - if ((u_int8_t *)rp < (u_int8_t *)&elp->links) - continue; - - *(void **)retp = rp; - -#define SHALLOC_FRAGMENT 32 - /* - * If there are at least SHALLOC_FRAGMENT additional bytes of - * memory, divide the chunk into two chunks. - */ - if ((u_int8_t *)rp >= - (u_int8_t *)&elp->links + SHALLOC_FRAGMENT) { - sp = rp; - *--sp = elp->len - - ((u_int8_t *)rp - (u_int8_t *)&elp->links); - elp->len -= *sp + sizeof(size_t); - return (0); - } - - /* - * Otherwise, we return the entire chunk, wasting some amount - * of space to keep the list compact. However, because the - * address we're returning to the user may not be the address - * of the start of the region for alignment reasons, set the - * size_t length fields back to the "real" length field to a - * flag value, so that we can find the real length during free. - */ -#define ILLEGAL_SIZE 1 - SH_LIST_REMOVE(elp, links, __data); - for (sp = rp; (u_int8_t *)--sp >= (u_int8_t *)&elp->links;) - *sp = ILLEGAL_SIZE; - return (0); - } - - /* Nothing found large enough; need to grow the region. */ - return (ENOMEM); -} - -/* - * __db_shalloc_free -- - * Free a shared memory allocation. - * - * PUBLIC: void __db_shalloc_free __P((void *, void *)); - */ -void -__db_shalloc_free(regionp, ptr) - void *regionp, *ptr; -{ - struct __data *elp, *lastp, *newp; - struct __head *hp; - size_t free_size, *sp; - int merged; - - /* - * Step back over flagged length fields to find the beginning of - * the object and its real size. - */ - for (sp = (size_t *)ptr; sp[-1] == ILLEGAL_SIZE; --sp) - ; - ptr = sp; - - newp = (struct __data *)((u_int8_t *)ptr - sizeof(size_t)); - free_size = newp->len; - - /* Trash the returned memory. */ -#ifdef DIAGNOSTIC - memset(ptr, 0xdb, free_size); -#endif - - /* - * Walk the list, looking for where this entry goes. - * - * We keep the free list sorted by address so that coalescing is - * trivial. - * - * XXX - * Probably worth profiling this to see how expensive it is. - */ - hp = (struct __head *)regionp; - for (elp = SH_LIST_FIRST(hp, __data), lastp = NULL; - elp != NULL && (void *)elp < (void *)ptr; - lastp = elp, elp = SH_LIST_NEXT(elp, links, __data)) - ; - - /* - * Elp is either NULL (we reached the end of the list), or the slot - * after the one that's being returned. Lastp is either NULL (we're - * returning the first element of the list) or the element before the - * one being returned. - * - * Check for coalescing with the next element. - */ - merged = 0; - if ((u_int8_t *)ptr + free_size == (u_int8_t *)elp) { - newp->len += elp->len + sizeof(size_t); - SH_LIST_REMOVE(elp, links, __data); - if (lastp != NULL) - SH_LIST_INSERT_AFTER(lastp, newp, links, __data); - else - SH_LIST_INSERT_HEAD(hp, newp, links, __data); - merged = 1; - } - - /* Check for coalescing with the previous element. */ - if (lastp != NULL && (u_int8_t *)lastp + - lastp->len + sizeof(size_t) == (u_int8_t *)newp) { - lastp->len += newp->len + sizeof(size_t); - - /* - * If we have already put the new element into the list take - * it back off again because it's just been merged with the - * previous element. - */ - if (merged) - SH_LIST_REMOVE(newp, links, __data); - merged = 1; - } - - if (!merged) { - if (lastp == NULL) - SH_LIST_INSERT_HEAD(hp, newp, links, __data); - else - SH_LIST_INSERT_AFTER(lastp, newp, links, __data); - } -} - -/* - * __db_shalloc_count -- - * Return the amount of memory on the free list. - * - * PUBLIC: size_t __db_shalloc_count __P((void *)); - */ -size_t -__db_shalloc_count(addr) - void *addr; -{ - struct __data *elp; - size_t count; - - count = 0; - for (elp = SH_LIST_FIRST((struct __head *)addr, __data); - elp != NULL; - elp = SH_LIST_NEXT(elp, links, __data)) - count += elp->len; - - return (count); -} - -/* - * __db_shsizeof -- - * Return the size of a shalloc'd piece of memory. - * - * PUBLIC: size_t __db_shsizeof __P((void *)); - */ -size_t -__db_shsizeof(ptr) - void *ptr; -{ - struct __data *elp; - size_t *sp; - - /* - * Step back over flagged length fields to find the beginning of - * the object and its real size. - */ - for (sp = (size_t *)ptr; sp[-1] == ILLEGAL_SIZE; --sp) - ; - - elp = (struct __data *)((u_int8_t *)sp - sizeof(size_t)); - return (elp->len); -} - -/* - * __db_shalloc_dump -- - * - * PUBLIC: void __db_shalloc_dump __P((void *, FILE *)); - */ -void -__db_shalloc_dump(addr, fp) - void *addr; - FILE *fp; -{ - struct __data *elp; - - /* Make it easy to call from the debugger. */ - if (fp == NULL) - fp = stderr; - - fprintf(fp, "%s\nMemory free list\n", DB_LINE); - - for (elp = SH_LIST_FIRST((struct __head *)addr, __data); - elp != NULL; - elp = SH_LIST_NEXT(elp, links, __data)) - fprintf(fp, "%#lx: %lu\t", (u_long)elp, (u_long)elp->len); - fprintf(fp, "\n"); -} |