/* $OpenBSD: hash.h,v 1.9 2004/06/21 23:13:22 marc Exp $ */ /*- * Copyright (c) 1990, 1993, 1994 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Margo Seltzer. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)hash.h 8.3 (Berkeley) 5/31/94 */ /* Operations */ typedef enum { HASH_GET, HASH_PUT, HASH_PUTNEW, HASH_DELETE, HASH_FIRST, HASH_NEXT } ACTION; /* Buffer Management structures */ typedef struct _bufhead BUFHEAD; struct _bufhead { BUFHEAD *prev; /* LRU links */ BUFHEAD *next; /* LRU links */ BUFHEAD *ovfl; /* Overflow page buffer header */ u_int32_t addr; /* Address of this page */ char *page; /* Actual page data */ char flags; #define BUF_MOD 0x0001 #define BUF_DISK 0x0002 #define BUF_BUCKET 0x0004 #define BUF_PIN 0x0008 }; #define IS_BUCKET(X) ((X) & BUF_BUCKET) typedef BUFHEAD **SEGMENT; /* Hash Table Information */ typedef struct hashhdr { /* Disk resident portion */ int32_t magic; /* Magic NO for hash tables */ int32_t version; /* Version ID */ u_int32_t lorder; /* Byte Order */ int32_t bsize; /* Bucket/Page Size */ int32_t bshift; /* Bucket shift */ int32_t dsize; /* Directory Size */ int32_t ssize; /* Segment Size */ int32_t sshift; /* Segment shift */ int32_t ovfl_point; /* Where overflow pages are being * allocated */ int32_t last_freed; /* Last overflow page freed */ int32_t max_bucket; /* ID of Maximum bucket in use */ int32_t high_mask; /* Mask to modulo into entire table */ int32_t low_mask; /* Mask to modulo into lower half of * table */ int32_t ffactor; /* Fill factor */ int32_t nkeys; /* Number of keys in hash table */ int32_t hdrpages; /* Size of table header */ int32_t h_charkey; /* value of hash(CHARKEY) */ #define NCACHED 32 /* number of bit maps and spare * points */ int32_t spares[NCACHED];/* spare pages for overflow */ u_int16_t bitmaps[NCACHED]; /* address of overflow page * bitmaps */ } HASHHDR; typedef struct htab { /* Memory resident data structure */ HASHHDR hdr; /* Header */ int nsegs; /* Number of allocated segments */ int exsegs; /* Number of extra allocated * segments */ u_int32_t /* Hash function */ (*hash)(const void *, size_t); int flags; /* Flag values */ int fp; /* File pointer */ char *tmp_buf; /* Temporary Buffer for BIG data */ char *tmp_key; /* Temporary Buffer for BIG keys */ BUFHEAD *cpage; /* Current page */ int cbucket; /* Current bucket */ int cndx; /* Index of next item on cpage */ int err; /* Error Number -- for DBM * compatibility */ int new_file; /* Indicates if fd is backing store * or no */ int save_file; /* Indicates whether we need to flush * file at * exit */ u_int32_t *mapp[NCACHED]; /* Pointers to page maps */ int nmaps; /* Initial number of bitmaps */ int nbufs; /* Number of buffers left to * allocate */ BUFHEAD bufhead; /* Header of buffer lru list */ SEGMENT *dir; /* Hash Bucket directory */ } HTAB; /* * Constants */ #define MAX_BSIZE 65536 /* 2^16 */ #define MIN_BUFFERS 6 #define MINHDRSIZE 512 #define DEF_BUFSIZE 65536 /* 64 K */ #define DEF_BUCKET_SIZE 4096 #define DEF_BUCKET_SHIFT 12 /* log2(BUCKET) */ #define DEF_SEGSIZE 256 #define DEF_SEGSIZE_SHIFT 8 /* log2(SEGSIZE) */ #define DEF_DIRSIZE 256 #define DEF_FFACTOR 65536 #define MIN_FFACTOR 4 #define SPLTMAX 8 #define CHARKEY "%$sniglet^&" #define NUMKEY 1038583 #define BYTE_SHIFT 3 #define INT_TO_BYTE 2 #define INT_BYTE_SHIFT 5 #define ALL_SET ((u_int32_t)0xFFFFFFFF) #define ALL_CLEAR 0 #define PTROF(X) ((BUFHEAD *)((ptrdiff_t)(X)&~0x3)) #define ISMOD(X) ((u_int32_t)(ptrdiff_t)(X)&0x1) #define DOMOD(X) ((X) = (char *)((ptrdiff_t)(X)|0x1)) #define ISDISK(X) ((u_int32_t)(ptrdiff_t)(X)&0x2) #define DODISK(X) ((X) = (char *)((ptrdiff_t)(X)|0x2)) #define BITS_PER_MAP 32 /* Given the address of the beginning of a big map, clear/set the nth bit */ #define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP))) #define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP))) #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) /* Overflow management */ /* * Overflow page numbers are allocated per split point. At each doubling of * the table, we can allocate extra pages. So, an overflow page number has * the top 5 bits indicate which split point and the lower 11 bits indicate * which page at that split point is indicated (pages within split points are * numberered starting with 1). */ #define SPLITSHIFT 11 #define SPLITMASK 0x7FF #define SPLITNUM(N) (((u_int32_t)(N)) >> SPLITSHIFT) #define OPAGENUM(N) ((N) & SPLITMASK) #define OADDR_OF(S,O) ((u_int32_t)((u_int32_t)(S) << SPLITSHIFT) + (O)) #define BUCKET_TO_PAGE(B) \ (B) + hashp->HDRPAGES + ((B) ? hashp->SPARES[__log2((B)+1)-1] : 0) #define OADDR_TO_PAGE(B) \ BUCKET_TO_PAGE ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B)); /* * page.h contains a detailed description of the page format. * * Normally, keys and data are accessed from offset tables in the top of * each page which point to the beginning of the key and data. There are * four flag values which may be stored in these offset tables which indicate * the following: * * * OVFLPAGE Rather than a key data pair, this pair contains * the address of an overflow page. The format of * the pair is: * OVERFLOW_PAGE_NUMBER OVFLPAGE * * PARTIAL_KEY This must be the first key/data pair on a page * and implies that page contains only a partial key. * That is, the key is too big to fit on a single page * so it starts on this page and continues on the next. * The format of the page is: * KEY_OFF PARTIAL_KEY OVFL_PAGENO OVFLPAGE * * KEY_OFF -- offset of the beginning of the key * PARTIAL_KEY -- 1 * OVFL_PAGENO - page number of the next overflow page * OVFLPAGE -- 0 * * FULL_KEY This must be the first key/data pair on the page. It * is used in two cases. * * Case 1: * There is a complete key on the page but no data * (because it wouldn't fit). The next page contains * the data. * * Page format it: * KEY_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE * * KEY_OFF -- offset of the beginning of the key * FULL_KEY -- 2 * OVFL_PAGENO - page number of the next overflow page * OVFLPAGE -- 0 * * Case 2: * This page contains no key, but part of a large * data field, which is continued on the next page. * * Page format it: * DATA_OFF FULL_KEY OVFL_PAGENO OVFL_PAGE * * KEY_OFF -- offset of the beginning of the data on * this page * FULL_KEY -- 2 * OVFL_PAGENO - page number of the next overflow page * OVFLPAGE -- 0 * * FULL_KEY_DATA * This must be the first key/data pair on the page. * There are two cases: * * Case 1: * This page contains a key and the beginning of the * data field, but the data field is continued on the * next page. * * Page format is: * KEY_OFF FULL_KEY_DATA OVFL_PAGENO DATA_OFF * * KEY_OFF -- offset of the beginning of the key * FULL_KEY_DATA -- 3 * OVFL_PAGENO - page number of the next overflow page * DATA_OFF -- offset of the beginning of the data * * Case 2: * This page contains the last page of a big data pair. * There is no key, only the tail end of the data * on this page. * * Page format is: * DATA_OFF FULL_KEY_DATA <OVFL_PAGENO> <OVFLPAGE> * * DATA_OFF -- offset of the beginning of the data on * this page * FULL_KEY_DATA -- 3 * OVFL_PAGENO - page number of the next overflow page * OVFLPAGE -- 0 * * OVFL_PAGENO and OVFLPAGE are optional (they are * not present if there is no next page). */ #define OVFLPAGE 0 #define PARTIAL_KEY 1 #define FULL_KEY 2 #define FULL_KEY_DATA 3 #define REAL_KEY 4 /* Short hands for accessing structure */ #define BSIZE hdr.bsize #define BSHIFT hdr.bshift #define DSIZE hdr.dsize #define SGSIZE hdr.ssize #define SSHIFT hdr.sshift #define LORDER hdr.lorder #define OVFL_POINT hdr.ovfl_point #define LAST_FREED hdr.last_freed #define MAX_BUCKET hdr.max_bucket #define FFACTOR hdr.ffactor #define HIGH_MASK hdr.high_mask #define LOW_MASK hdr.low_mask #define NKEYS hdr.nkeys #define HDRPAGES hdr.hdrpages #define SPARES hdr.spares #define BITMAPS hdr.bitmaps #define VERSION hdr.version #define MAGIC hdr.magic #define NEXT_FREE hdr.next_free #define H_CHARKEY hdr.h_charkey
