2 * CDE - Common Desktop Environment
4 * Copyright (c) 1993-2012, The Open Group. All rights reserved.
6 * These libraries and programs are free software; you can
7 * redistribute them and/or modify them under the terms of the GNU
8 * Lesser General Public License as published by the Free Software
9 * Foundation; either version 2 of the License, or (at your option)
12 * These libraries and programs are distributed in the hope that
13 * they will be useful, but WITHOUT ANY WARRANTY; without even the
14 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
15 * PURPOSE. See the GNU Lesser General Public License for more
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with these libraries and programs; if not, write
20 * to the Free Software Foundation, Inc., 51 Franklin Street, Fifth
21 * Floor, Boston, MA 02110-1301 USA
23 /*%% (c) Copyright 1993, 1994 Hewlett-Packard Company */
24 /*%% (c) Copyright 1993, 1994 International Business Machines Corp. */
25 /*%% (c) Copyright 1993, 1994 Sun Microsystems, Inc. */
26 /*%% (c) Copyright 1993, 1994 Novell, Inc. */
27 /*%% $XConsortium: isdiskbufs2.c /main/3 1995/10/23 11:37:47 rswiston $ */
30 * Copyright (c) 1988 by Sun Microsystems, Inc.
37 * ISAM disk buffer managament
41 /************************ NON MAPPED I/O version ***************************/
43 #include "isam_impl.h"
45 extern struct dlink *_isdln_next(), *_isdln_first();
47 #define ISMAXBUFFERS 200 /* Use 20 buffers */
48 #define ISHASHHDRS 256 /* Must be a power of two */
49 #define ISHASHMASK (ISHASHHDRS-1)
51 #define __hashblkno(fcb,blkno) (((size_t)(fcb)+(blkno)) & ISHASHMASK)
54 #define base ((char *)0)
55 #define _isdln_insert(l,e) _isdln_base_insert(base,(l),(e))
56 #define _isdln_append(l,e) _isdln_base_append(base,(l),(e))
57 #define _isdln_remove(e) _isdln_base_remove(base,(e))
58 #define _isdln_first(l) _isdln_base_first(base,(l))
59 #define _isdln_next(l) _isdln_base_next(base,(l))
60 #define _isdln_prev(l) _isdln_base_prev(base,(l))
61 #define _isdln_makeempty(l) _isdln_base_makeempty(base,(l))
62 #define _isdln_isempty(l) _isdln_base_isempty(base,(l))
64 /*---------------------- Local data ---------------------------------------*/
65 static Bufhdr *_getavail(), *_findblock();
66 static void _disk_init(), _commit1buffer(), _rollback1buffer(), _flush1buffer();
67 static void _makenodata();
69 Bufhdr bufhdrs [ISMAXBUFFERS];
70 struct dlink hashhdrs [ISHASHHDRS]; /* Heads of hashed lists */
72 struct dlink availlist; /* Available buffer list */
73 struct dlink *pavail = &availlist;
75 struct dlink changelist; /* Change buffer list */
76 struct dlink *pchangl = &changelist;
78 struct dlink fixlist; /* Fixed buffer list */
79 struct dlink *pfixl = &fixlist;
81 static int availn; /* Number of available buffers */
82 static int minavailn; /* Minimum available buffers */
83 static int maxavailn; /* Stop flushing when
84 * when maxavailn buffers
88 #define ISB_FIXED (ISB_RFIXED | ISB_WFIXED)
89 #define MINAVAILN 40 /* in procent of total # buffers */
90 #define MAXAVAILN 60 /* in procent of total # buffers */
94 /* unixfd, .rec, .ind., .var */
96 _isdisk_fix(Fcb *fcb, int unixfd, Blkno blkno, int mode)
102 * Initialize some local data.
106 if (fcb->datfd == unixfd)
107 assert(blkno != 0); /* Never access control page */
109 hashl = (hashhdrs +__hashblkno(fcb,blkno));
111 /* Try to find the page in buffer pool. */
112 if ((p = _findblock(fcb, unixfd, blkno)) == NULL) {
114 /* Page is not in the pool - install it. */
115 if (mode != ISFIXNOREAD) {
116 p = _getavail(); /* Get free page from pool */
117 _isdln_insert(hashl,&p->isb_hash); /* Insert into hash list */
119 _isseekpg(unixfd, blkno);
120 _isreadpg(unixfd, p->isb_buffer);
122 p->isb_flags = ISB_READ;
123 p->isb_oldcopy = NULL;
125 p->isb_unixfd = unixfd;
126 p->isb_blkno = blkno;
132 if (p && (p->isb_flags & ISB_FIXED)==0) {
134 /* Remove buffer from pavail (or pchangl) list. */
135 _isdln_remove(&p->isb_aclist);
138 if (!(p->isb_flags & ISB_CHANGE))
143 if (mode == ISFIXREAD) {
146 if(!(p->isb_flags & ISB_FIXED)) {
148 /* Add buffer to pfixl list. */
149 _isdln_append(pfixl,&p->isb_flist);
150 p->isb_flags |= ISB_RFIXED;
157 /* If buffer is already fixed for write, no other actions are necces. */
158 if (p && p->isb_flags & ISB_FIXED) {
159 assert((p->isb_flags & ISB_RFIXED) == 0); /* Buffer cannot be */
160 /* fixed for read when is fixed */
161 /* being fixed for write */
165 /* Create shadow page */
166 p2 = _getavail(); /* Get free page from pool */
168 _isdln_remove(&p2->isb_aclist); /* Remove from pavail */
169 _isdln_insert(hashl,&p2->isb_hash); /* Insert into hash list */
170 _isdln_insert(pfixl,&p2->isb_flist); /* Insert into pfixl list */
173 p2->isb_unixfd = unixfd;
174 p2->isb_blkno = blkno;
175 p2->isb_flags = ISB_READ|ISB_WFIXED; /* Mark buffer as dirty */
177 if (mode == ISFIXWRITE) /* Copy buffer content */
178 memcpy(p2->isb_buffer,p->isb_buffer,ISPAGESIZE);
184 assert ((p->isb_flags & ISB_FIXED) == 0);
185 assert((p->isb_flags & ISB_OLDCOPY) == 0);
187 p->isb_flags |= ISB_OLDCOPY;
188 _isdln_remove(&p->isb_hash);
196 _isdisk_unfix (Bufhdr *p)
198 if (!(p->isb_flags & ISB_FIXED))
199 assert(p->isb_flags & ISB_FIXED);
201 if (p->isb_flags & ISB_WFIXED) /* Unfix at commit/abort time */
204 p->isb_flags &= ~ISB_FIXED; /* Clear bit */
205 _isdln_remove(&p->isb_flist); /* Remove from pfixl */
207 /* Append to pavail or pchangl list. */
208 if (p->isb_flags & ISB_CHANGE)
209 _isdln_append(pchangl,&p->isb_aclist); /* Append to pchangl list */
211 _isdln_append(pavail,&p->isb_aclist); /* Append to pavail list */
217 _isdisk_commit1 (Bufhdr *p)
228 while ((e = _isdln_first(pfixl)) != pfixl) {
229 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
230 assert(p->isb_flags & ISB_WFIXED);
236 _isdisk_rollback(void)
241 while ((e = _isdln_first(pfixl)) != pfixl) {
242 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
243 assert(p->isb_flags & ISB_FIXED);
244 if (p->isb_flags & ISB_WFIXED)
252 _isdisk_refix(Bufhdr *p, int newmode)
254 Blkno blkno = p->isb_blkno;
255 Fcb *fcb = p->isb_fcb;
256 int unixfd = p->isb_unixfd;
258 assert(newmode == ISFIXWRITE);
260 if (p->isb_flags & ISB_RFIXED) {
262 return (_isdisk_fix(fcb, unixfd, blkno, ISFIXWRITE));
271 extern time_t _istimeget();
275 while ((e = _isdln_first(pchangl)) != pchangl) {
276 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
277 assert(p->isb_flags & ISB_CHANGE);
278 assert((p->isb_flags & ISB_FIXED)==0);
286 extern time_t _istimeget();
290 /* ensure pavail is initialized before using it */
292 if (pavail->dln_forward == 0) {
293 _isdln_makeempty(pavail);
298 while ((e = _isdln_prev(e)) != pavail) {
299 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
301 if ((p->isb_flags & ISB_READ) == 0)
304 _isdln_remove(&p->isb_hash);
305 p->isb_flags = ISB_NODATA; /* Mark as no data in the buffer */
316 (void)printf("\nInd isfd blkno mode temp oldcopy\n");
317 for (p = bufhdrs, i = 0; i < ISMAXBUFFERS; p++,i++)
318 if (p->isb_flags != ISB_NODATA)
319 (void) printf("%3d: %3d %6d %2x %3d\n",i,
320 _isfd_getisfd(p->isb_pisfd),
321 p->isb_blkno,p->isb_flags,
322 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
325 aclistdump(struct dlink *lh)
330 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
331 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
332 (void) printf("%3d: %3d %6d %2x %3d\n",p-bufhdrs,
333 _isfd_getisfd(p->isb_pisfd),
334 p->isb_blkno,p->isb_flags,
335 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
339 flistdump(struct dlink *lh)
344 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
345 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
346 (void) printf("%3d: %3d %6d %2x %3d\n",p-bufhdrs,
347 _isfd_getisfd(p->isb_pisfd),
348 p->isb_blkno,p->isb_flags,
349 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
356 /*------------------------ Local functions ---------------------------------*/
361 static Bool initialized = FALSE;
364 if (initialized == TRUE)
369 /* Initialize hash queue list heads. */
370 for (i = 0; i < ISHASHHDRS; i++) {
371 _isdln_makeempty(hashhdrs+i);
374 /* initialize pavail, pchangel, and pfixl lists to empty. */
376 _isdln_makeempty(pavail);
377 _isdln_makeempty(pchangl);
378 _isdln_makeempty(pfixl);
380 /* Link all buffers into pavail list. */
381 for (i = 0; i < ISMAXBUFFERS; i++) {
382 bufhdrs[i].isb_buffer = _ismalloc(ISPAGESIZE);
383 _isdln_append(pavail,&bufhdrs[i].isb_aclist);
387 /* Set maxavailn and minavailn. */
388 minavailn = (ISMAXBUFFERS * MINAVAILN) / 100;
389 maxavailn = (ISMAXBUFFERS * MAXAVAILN) / 100;
392 /* _getavail() - get available buffer in disk */
399 if ((q = _isdln_first(pavail)) == pavail) {
400 _isfatal_error("No buffer in pool available");
403 p = GETBASE(q,bufhdr,isb_aclist);
405 if (p->isb_flags & ISB_READ) { /* Remove from hash queue */
406 _isdln_remove(&p->isb_hash);
407 p->isb_flags = ISB_NODATA; /* Mark as no data in the buffer */
410 return ((Bufhdr *) p);
413 /* _findblock() - Find block in buffer pool */
415 _findblock(Fcb *fcb, int unixfd, Blkno blkno)
418 struct dlink *lh, *e;
421 hashval = __hashblkno(fcb,blkno);
423 lh = hashhdrs + hashval; /* lh is list head */
424 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
425 p = GETBASE(e,bufhdr,isb_hash); /* Get pointer to bufhdr */
426 if (p->isb_blkno == blkno && p->isb_fcb == fcb && p->isb_unixfd == unixfd) {
427 assert(p->isb_flags != ISB_NODATA);
435 /* _commit1buffer() - Commit changes to buffer */
437 _commit1buffer(Bufhdr *p)
439 assert(p->isb_flags & ISB_WFIXED); /* Fixed for read buffers should */
440 /* go through _isdisk_unfix() */
442 /* Free old permanent buffer if any exists. */
443 if (p->isb_oldcopy) {
444 _makenodata(p->isb_oldcopy); /* Make this buffer available */
447 /* Remove buffer from list of fixed buffers. */
448 /* Append buffer to list of changed buffers. */
449 _isdln_remove(&p->isb_flist);
450 _isdln_append(pchangl,&p->isb_aclist);
451 p->isb_flags &= ~ISB_FIXED;
452 p->isb_flags |= ISB_CHANGE;
455 /* _rollback1buffer() - Rollback changes to buffer */
457 _rollback1buffer(Bufhdr *p)
461 assert(p->isb_flags & ISB_WFIXED); /* Fixed for read buffers should */
462 /* go through _isdisk_unfix() */
464 /* Re-install old copy if that exists. */
465 if ((p2 = p->isb_oldcopy) != NULL) {
466 if (p2->isb_flags & ISB_CHANGE) {
467 _isdln_append(pchangl,&p2->isb_aclist);
470 _isdln_append(pavail,&p2->isb_aclist);
473 p2->isb_flags &= ~ISB_OLDCOPY; /* Clear bit */
475 /* See implementation of _isdln_append() that this will work. */
476 _isdln_append(&p->isb_hash,&p2->isb_hash); /* Insert into hash list */
480 _isdln_remove(&p->isb_hash); /* Remove bufer from hash list */
481 _isdln_remove(&p->isb_flist); /* Remove bufer from pfixl */
482 _makenodata(p); /* Make this buffer available */
485 /* _makenodata() - make buffer available with no data in it*/
487 _makenodata(Bufhdr *p)
489 assert(p->isb_flags & ISB_READ);
491 p->isb_flags = ISB_NODATA;
492 _isdln_insert(pavail,&p->isb_aclist);
496 /* _flush1buffer() - flush buffer to disk */
498 _flush1buffer(Bufhdr *p)
500 assert(p->isb_flags & ISB_CHANGE);
502 _isseekpg(p->isb_unixfd, p->isb_blkno);
503 _iswritepg(p->isb_unixfd, p->isb_buffer);
505 p->isb_flags &= ~ISB_CHANGE; /* clear change flag */
507 _isdln_remove(&p->isb_aclist); /* Remove from pchangl */
508 _isdln_append(pavail,&p->isb_aclist); /* Append to pavail */