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 librararies 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 $ */
29 static char sccsid[] = "@(#)isdiskbufs2.c 1.3 89/07/17 Copyr 1988 Sun Micro";
33 * Copyright (c) 1988 by Sun Microsystems, Inc.
40 * ISAM disk buffer managament
44 /************************ NON MAPPED I/O version ***************************/
46 #include "isam_impl.h"
48 extern struct dlink *_isdln_next(), *_isdln_first();
50 #define ISMAXBUFFERS 200 /* Use 20 buffers */
51 #define ISHASHHDRS 256 /* Must be a power of two */
52 #define ISHASHMASK (ISHASHHDRS-1)
54 #define __hashblkno(fcb,blkno) (((int)(fcb)+(blkno)) & ISHASHMASK)
57 #define base ((char *)0)
58 #define _isdln_insert(l,e) _isdln_base_insert(base,(l),(e))
59 #define _isdln_append(l,e) _isdln_base_append(base,(l),(e))
60 #define _isdln_remove(e) _isdln_base_remove(base,(e))
61 #define _isdln_first(l) _isdln_base_first(base,(l))
62 #define _isdln_next(l) _isdln_base_next(base,(l))
63 #define _isdln_prev(l) _isdln_base_prev(base,(l))
64 #define _isdln_makeempty(l) _isdln_base_makeempty(base,(l))
65 #define _isdln_isempty(l) _isdln_base_isempty(base,(l))
67 /*---------------------- Local data ---------------------------------------*/
68 static Bufhdr *_getavail(), *_findblock();
69 static void _disk_init(), _commit1buffer(), _rollback1buffer(), _flush1buffer();
70 static void _makenodata();
72 Bufhdr bufhdrs [ISMAXBUFFERS];
73 struct dlink hashhdrs [ISHASHHDRS]; /* Heads of hashed lists */
75 struct dlink availlist; /* Available buffer list */
76 struct dlink *pavail = &availlist;
78 struct dlink changelist; /* Change buffer list */
79 struct dlink *pchangl = &changelist;
81 struct dlink fixlist; /* Fixed buffer list */
82 struct dlink *pfixl = &fixlist;
84 static int availn; /* Number of available buffers */
85 static int minavailn; /* Minimum available buffers */
86 static int maxavailn; /* Stop flushing when
87 * when maxavailn buffers
91 #define ISB_FIXED (ISB_RFIXED | ISB_WFIXED)
92 #define MINAVAILN 40 /* in procent of total # buffers */
93 #define MAXAVAILN 60 /* in procent of total # buffers */
98 _isdisk_fix(fcb, unixfd, blkno, mode)
100 int unixfd; /* .rec, .ind., .var */
104 register Bufhdr *p, *p2;
108 * Initialize some local data.
112 if (fcb->datfd == unixfd)
113 assert(blkno != 0); /* Never access control page */
115 hashl = (hashhdrs +__hashblkno(fcb,blkno));
117 /* Try to find the page in buffer pool. */
118 if ((p = _findblock(fcb, unixfd, blkno)) == NULL) {
120 /* Page is not in the pool - install it. */
121 if (mode != ISFIXNOREAD) {
122 p = _getavail(); /* Get free page from pool */
123 _isdln_insert(hashl,&p->isb_hash); /* Insert into hash list */
125 _isseekpg(unixfd, blkno);
126 _isreadpg(unixfd, p->isb_buffer);
128 p->isb_flags = ISB_READ;
129 p->isb_oldcopy = NULL;
131 p->isb_unixfd = unixfd;
132 p->isb_blkno = blkno;
138 if (p && (p->isb_flags & ISB_FIXED)==0) {
140 /* Remove buffer from pavail (or pchangl) list. */
141 _isdln_remove(&p->isb_aclist);
144 if (!(p->isb_flags & ISB_CHANGE))
149 if (mode == ISFIXREAD) {
152 if(!(p->isb_flags & ISB_FIXED)) {
154 /* Add buffer to pfixl list. */
155 _isdln_append(pfixl,&p->isb_flist);
156 p->isb_flags |= ISB_RFIXED;
163 /* If buffer is already fixed for write, no other actions are necces. */
164 if (p && p->isb_flags & ISB_FIXED) {
165 assert((p->isb_flags & ISB_RFIXED) == 0); /* Buffer cannot be */
166 /* fixed for read when is fixed */
167 /* being fixed for write */
171 /* Create shadow page */
172 p2 = _getavail(); /* Get free page from pool */
174 _isdln_remove(&p2->isb_aclist); /* Remove from pavail */
175 _isdln_insert(hashl,&p2->isb_hash); /* Insert into hash list */
176 _isdln_insert(pfixl,&p2->isb_flist); /* Insert into pfixl list */
179 p2->isb_unixfd = unixfd;
180 p2->isb_blkno = blkno;
181 p2->isb_flags = ISB_READ|ISB_WFIXED; /* Mark buffer as dirty */
183 if (mode == ISFIXWRITE) /* Copy buffer content */
184 memcpy(p2->isb_buffer,p->isb_buffer,ISPAGESIZE);
190 assert ((p->isb_flags & ISB_FIXED) == 0);
191 assert((p->isb_flags & ISB_OLDCOPY) == 0);
193 p->isb_flags |= ISB_OLDCOPY;
194 _isdln_remove(&p->isb_hash);
205 if (!(p->isb_flags & ISB_FIXED))
206 assert(p->isb_flags & ISB_FIXED);
208 if (p->isb_flags & ISB_WFIXED) /* Unfix at commit/abort time */
211 p->isb_flags &= ~ISB_FIXED; /* Clear bit */
212 _isdln_remove(&p->isb_flist); /* Remove from pfixl */
214 /* Append to pavail or pchangl list. */
215 if (p->isb_flags & ISB_CHANGE)
216 _isdln_append(pchangl,&p->isb_aclist); /* Append to pchangl list */
218 _isdln_append(pavail,&p->isb_aclist); /* Append to pavail list */
236 while ((e = _isdln_first(pfixl)) != pfixl) {
237 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
238 assert(p->isb_flags & ISB_WFIXED);
249 while ((e = _isdln_first(pfixl)) != pfixl) {
250 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
251 assert(p->isb_flags & ISB_FIXED);
252 if (p->isb_flags & ISB_WFIXED)
260 _isdisk_refix(p, newmode)
264 Blkno blkno = p->isb_blkno;
265 Fcb *fcb = p->isb_fcb;
266 int unixfd = p->isb_unixfd;
268 assert(newmode == ISFIXWRITE);
270 if (p->isb_flags & ISB_RFIXED) {
272 return (_isdisk_fix(fcb, unixfd, blkno, ISFIXWRITE));
281 extern time_t _istimeget();
285 while ((e = _isdln_first(pchangl)) != pchangl) {
286 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
287 assert(p->isb_flags & ISB_CHANGE);
288 assert((p->isb_flags & ISB_FIXED)==0);
296 extern time_t _istimeget();
300 /* ensure pavail is initialized before using it */
302 if (pavail->dln_forward == 0) {
303 _isdln_makeempty(pavail);
308 while ((e = _isdln_prev(e)) != pavail) {
309 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
311 if ((p->isb_flags & ISB_READ) == 0)
314 _isdln_remove(&p->isb_hash);
315 p->isb_flags = ISB_NODATA; /* Mark as no data in the buffer */
326 (void)printf("\nInd isfd blkno mode temp oldcopy\n");
327 for (p = bufhdrs, i = 0; i < ISMAXBUFFERS; p++,i++)
328 if (p->isb_flags != ISB_NODATA)
329 (void) printf("%3d: %3d %6d %2x %3d\n",i,
330 _isfd_getisfd(p->isb_pisfd),
331 p->isb_blkno,p->isb_flags,
332 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
341 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
342 p = GETBASE(e,bufhdr,isb_aclist); /* Get pointer to bufhdr */
343 (void) printf("%3d: %3d %6d %2x %3d\n",p-bufhdrs,
344 _isfd_getisfd(p->isb_pisfd),
345 p->isb_blkno,p->isb_flags,
346 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
356 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
357 p = GETBASE(e,bufhdr,isb_flist); /* Get pointer to bufhdr */
358 (void) printf("%3d: %3d %6d %2x %3d\n",p-bufhdrs,
359 _isfd_getisfd(p->isb_pisfd),
360 p->isb_blkno,p->isb_flags,
361 p->isb_oldcopy?(p->isb_oldcopy - bufhdrs):-1);
368 /*------------------------ Local functions ---------------------------------*/
373 static Bool initialized = FALSE;
376 if (initialized == TRUE)
381 /* Initialize hash queue list heads. */
382 for (i = 0; i < ISHASHHDRS; i++) {
383 _isdln_makeempty(hashhdrs+i);
386 /* initialize pavail, pchangel, and pfixl lists to empty. */
388 _isdln_makeempty(pavail);
389 _isdln_makeempty(pchangl);
390 _isdln_makeempty(pfixl);
392 /* Link all buffers into pavail list. */
393 for (i = 0; i < ISMAXBUFFERS; i++) {
394 bufhdrs[i].isb_buffer = _ismalloc(ISPAGESIZE);
395 _isdln_append(pavail,&bufhdrs[i].isb_aclist);
399 /* Set maxavailn and minavailn. */
400 minavailn = (ISMAXBUFFERS * MINAVAILN) / 100;
401 maxavailn = (ISMAXBUFFERS * MAXAVAILN) / 100;
404 /* _getavail() - get available buffer in disk */
409 register struct dlink *q;
411 if ((q = _isdln_first(pavail)) == pavail) {
412 _isfatal_error("No buffer in pool available");
415 p = GETBASE(q,bufhdr,isb_aclist);
417 if (p->isb_flags & ISB_READ) { /* Remove from hash queue */
418 _isdln_remove(&p->isb_hash);
419 p->isb_flags = ISB_NODATA; /* Mark as no data in the buffer */
422 return ((Bufhdr *) p);
425 /* _findblock() - Find block in buffer pool */
427 _findblock(fcb, unixfd, blkno)
433 struct dlink *lh, *e;
436 hashval = __hashblkno(fcb,blkno);
438 lh = hashhdrs + hashval; /* lh is list head */
439 for (e = _isdln_first(lh); e != lh; e = _isdln_next(e)) {
440 p = GETBASE(e,bufhdr,isb_hash); /* Get pointer to bufhdr */
441 if (p->isb_blkno == blkno && p->isb_fcb == fcb && p->isb_unixfd == unixfd) {
442 assert(p->isb_flags != ISB_NODATA);
450 /* _commit1buffer() - Commit changes to buffer */
455 assert(p->isb_flags & ISB_WFIXED); /* Fixed for read buffers should */
456 /* go through _isdisk_unfix() */
458 /* Free old permanent buffer if any exists. */
459 if (p->isb_oldcopy) {
460 _makenodata(p->isb_oldcopy); /* Make this buffer available */
463 /* Remove buffer from list of fixed buffers. */
464 /* Append buffer to list of changed buffers. */
465 _isdln_remove(&p->isb_flist);
466 _isdln_append(pchangl,&p->isb_aclist);
467 p->isb_flags &= ~ISB_FIXED;
468 p->isb_flags |= ISB_CHANGE;
471 /* _rollback1buffer() - Rollback changes to buffer */
478 assert(p->isb_flags & ISB_WFIXED); /* Fixed for read buffers should */
479 /* go through _isdisk_unfix() */
481 /* Re-install old copy if that exists. */
482 if ((p2 = p->isb_oldcopy) != NULL) {
483 if (p2->isb_flags & ISB_CHANGE) {
484 _isdln_append(pchangl,&p2->isb_aclist);
487 _isdln_append(pavail,&p2->isb_aclist);
490 p2->isb_flags &= ~ISB_OLDCOPY; /* Clear bit */
492 /* See implementation of _isdln_append() that this will work. */
493 _isdln_append(&p->isb_hash,&p2->isb_hash); /* Insert into hash list */
497 _isdln_remove(&p->isb_hash); /* Remove bufer from hash list */
498 _isdln_remove(&p->isb_flist); /* Remove bufer from pfixl */
499 _makenodata(p); /* Make this buffer available */
502 /* _makenodata() - make buffer available with no data in it*/
507 assert(p->isb_flags & ISB_READ);
509 p->isb_flags = ISB_NODATA;
510 _isdln_insert(pavail,&p->isb_aclist);
514 /* _flush1buffer() - flush buffer to disk */
519 assert(p->isb_flags & ISB_CHANGE);
521 _isseekpg(p->isb_unixfd, p->isb_blkno);
522 _iswritepg(p->isb_unixfd, p->isb_buffer);
524 p->isb_flags &= ~ISB_CHANGE; /* clear change flag */
526 _isdln_remove(&p->isb_aclist); /* Remove from pchangl */
527 _isdln_append(pavail,&p->isb_aclist); /* Append to pavail */