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Diffstat (limited to 'db/hash/hash.h')
| -rw-r--r-- | db/hash/hash.h | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/db/hash/hash.h b/db/hash/hash.h new file mode 100644 index 0000000000..913e82b400 --- /dev/null +++ b/db/hash/hash.h @@ -0,0 +1,293 @@ +/*- + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. 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 */ + int magic; /* Magic NO for hash tables */ + int version; /* Version ID */ + u_int32_t lorder; /* Byte Order */ + int bsize; /* Bucket/Page Size */ + int bshift; /* Bucket shift */ + int dsize; /* Directory Size */ + int ssize; /* Segment Size */ + int sshift; /* Segment shift */ + int ovfl_point; /* Where overflow pages are being + * allocated */ + int last_freed; /* Last overflow page freed */ + int max_bucket; /* ID of Maximum bucket in use */ + int high_mask; /* Mask to modulo into entire table */ + int low_mask; /* Mask to modulo into lower half of + * table */ + int ffactor; /* Fill factor */ + int nkeys; /* Number of keys in hash table */ + int hdrpages; /* Size of table header */ + int h_charkey; /* value of hash(CHARKEY) */ +#define NCACHED 32 /* number of bit maps and spare + * points */ + int 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)__P((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 errno; /* Error Number -- for DBM + * compatability */ + 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 |