2 * Copyright 2000, International Business Machines Corporation and others.
5 * This software has been released under the terms of the IBM Public
6 * License. For details, see the LICENSE file in the top-level source
7 * directory or online at http://www.openafs.org/dl/license10.html
10 #include <afsconfig.h>
11 #include "afs/param.h"
14 #include "afs/sysincludes.h" /*Standard vendor system headers */
15 #include "afsincludes.h" /*AFS-based standard headers */
18 #include "afs/afs_stats.h"
19 #include "afs/afs_osidnlc.h"
22 * also cache failed lookups.
23 * look into interactions of dnlc and readdir.
24 * cache larger names, perhaps by using a better,longer key (SHA) and discarding
25 * the actual name itself.
26 * precompute a key and stuff for \sys, and combine the HandleAtName function with
27 * this, since we're looking at the name anyway.
30 struct afs_lock afs_xdnlc;
31 extern struct afs_lock afs_xvcache;
33 dnlcstats_t dnlcstats;
36 #define NHSIZE 256 /* must be power of 2. == NHASHENT in dir package */
37 struct nc *ncfreelist = NULL;
38 static struct nc nameCache[NCSIZE];
39 struct nc *nameHash[NHSIZE];
40 /* Hash table invariants:
41 * 1. If nameHash[i] is NULL, list is empty
42 * 2. A single element in a hash bucket has itself as prev and next.
45 typedef enum { osi_dnlc_enterT, InsertEntryT, osi_dnlc_lookupT,
46 ScavengeEntryT, osi_dnlc_removeT, RemoveEntryT, osi_dnlc_purgedpT,
47 osi_dnlc_purgevpT, osi_dnlc_purgeT
57 struct dt dnlctracetable[256];
60 #define TRACE(e,s) /* if (dnlct == 256) dnlct = 0; dnlctracetable[dnlct].event = e; dnlctracetable[dnlct++].slot = s; */
62 #define dnlcHash(ts, hval) for (hval=0; *ts; ts++) { hval *= 173; hval += *ts; }
67 static unsigned int nameptr = 0; /* next bucket to pull something from */
73 ncfreelist = tnc->next;
77 for (j = 0; j < NHSIZE + 2; j++, nameptr++) {
78 if (nameptr >= NHSIZE)
80 if (nameHash[nameptr])
84 if (nameptr >= NHSIZE)
87 TRACE(ScavengeEntryT, nameptr);
88 tnc = nameHash[nameptr];
89 if (!tnc) /* May want to consider changing this to return 0 */
90 osi_Panic("null tnc in GetMeAnEntry");
92 if (tnc->prev == tnc) { /* only thing in list, don't screw around */
93 nameHash[nameptr] = NULL;
97 tnc = tnc->prev; /* grab oldest one in this bucket */
98 /* remove it from list */
99 tnc->next->prev = tnc->prev;
100 tnc->prev->next = tnc->next;
106 InsertEntry(struct nc *tnc)
109 key = tnc->key & (NHSIZE - 1);
111 TRACE(InsertEntryT, key);
112 if (!nameHash[key]) {
114 tnc->next = tnc->prev = tnc;
116 tnc->next = nameHash[key];
117 tnc->prev = tnc->next->prev;
118 tnc->next->prev = tnc;
119 tnc->prev->next = tnc;
126 osi_dnlc_enter(struct vcache *adp, char *aname, struct vcache *avc,
130 unsigned int key, skey;
137 TRACE(osi_dnlc_enterT, 0);
138 dnlcHash(ts, key); /* leaves ts pointing at the NULL */
139 if (ts - aname >= AFSNCNAMESIZE) {
142 skey = key & (NHSIZE - 1);
146 ObtainWriteLock(&afs_xdnlc, 222);
148 /* Only cache entries from the latest version of the directory */
149 if (!(adp->f.states & CStatd) || !hsame(*avno, adp->f.m.DataVersion)) {
150 ReleaseWriteLock(&afs_xdnlc);
155 * Make sure each directory entry gets cached no more than once.
157 for (tnc = nameHash[skey], safety = 0; tnc; tnc = tnc->next, safety++) {
158 if ((tnc->dirp == adp) && (!strcmp((char *)tnc->name, aname))) {
159 /* duplicate entry */
161 } else if (tnc->next == nameHash[skey]) { /* end of list */
164 } else if (safety > NCSIZE) {
165 afs_warn("DNLC cycle");
167 ReleaseWriteLock(&afs_xdnlc);
174 tnc = GetMeAnEntry();
179 memcpy((char *)tnc->name, aname, ts - aname + 1); /* include the NULL */
186 ReleaseWriteLock(&afs_xdnlc);
193 osi_dnlc_lookup(struct vcache *adp, char *aname, int locktype)
196 unsigned int key, skey;
200 #ifdef AFS_DARWIN80_ENV
207 dnlcHash(ts, key); /* leaves ts pointing at the NULL */
208 if (ts - aname >= AFSNCNAMESIZE)
210 skey = key & (NHSIZE - 1);
212 TRACE(osi_dnlc_lookupT, skey);
215 ObtainReadLock(&afs_xvcache);
216 ObtainReadLock(&afs_xdnlc);
218 for (tvc = NULL, tnc = nameHash[skey], safety = 0; tnc;
219 tnc = tnc->next, safety++) {
220 if ( /* (tnc->key == key) && */ (tnc->dirp == adp)
221 && (!strcmp((char *)tnc->name, aname))) {
224 } else if (tnc->next == nameHash[skey]) { /* end of list */
226 } else if (safety > NCSIZE) {
227 afs_warn("DNLC cycle");
229 ReleaseReadLock(&afs_xdnlc);
230 ReleaseReadLock(&afs_xvcache);
236 ReleaseReadLock(&afs_xdnlc);
239 ReleaseReadLock(&afs_xvcache);
242 if ((tvc->f.states & CVInit)
243 #ifdef AFS_DARWIN80_ENV
244 ||(tvc->f.states & CDeadVnode)
248 ReleaseReadLock(&afs_xvcache);
250 osi_dnlc_remove(adp, aname, tvc);
253 #if defined(AFS_DARWIN80_ENV)
255 if (vnode_get(tvp)) {
256 ReleaseReadLock(&afs_xvcache);
258 osi_dnlc_remove(adp, aname, tvc);
261 if (vnode_ref(tvp)) {
262 ReleaseReadLock(&afs_xvcache);
267 osi_dnlc_remove(adp, aname, tvc);
273 ReleaseReadLock(&afs_xvcache);
282 RemoveEntry(struct nc *tnc, unsigned int key)
284 if (!tnc->prev) /* things on freelist always have null prev ptrs */
285 osi_Panic("bogus free list");
287 TRACE(RemoveEntryT, key);
288 if (tnc == tnc->next) { /* only one in list */
289 nameHash[key] = NULL;
291 if (tnc == nameHash[key])
292 nameHash[key] = tnc->next;
293 tnc->prev->next = tnc->next;
294 tnc->next->prev = tnc->prev;
297 tnc->prev = NULL; /* everything not in hash table has 0 prev */
298 tnc->key = 0; /* just for safety's sake */
303 osi_dnlc_remove(struct vcache *adp, char *aname, struct vcache *avc)
305 unsigned int key, skey;
312 TRACE(osi_dnlc_removeT, skey);
313 dnlcHash(ts, key); /* leaves ts pointing at the NULL */
314 if (ts - aname >= AFSNCNAMESIZE) {
317 skey = key & (NHSIZE - 1);
318 TRACE(osi_dnlc_removeT, skey);
320 ObtainReadLock(&afs_xdnlc);
322 for (tnc = nameHash[skey]; tnc; tnc = tnc->next) {
323 if ((tnc->dirp == adp) && (tnc->key == key)
324 && (!strcmp((char *)tnc->name, aname))) {
325 tnc->dirp = NULL; /* now it won't match anything */
327 } else if (tnc->next == nameHash[skey]) { /* end of list */
332 ReleaseReadLock(&afs_xdnlc);
337 /* there is a little race condition here, but it's relatively
338 * harmless. At worst, I wind up removing a mapping that I just
340 if (EWOULDBLOCK == NBObtainWriteLock(&afs_xdnlc, 1)) {
341 return 0; /* no big deal, tnc will get recycled eventually */
343 RemoveEntry(tnc, skey);
344 tnc->next = ncfreelist;
346 ReleaseWriteLock(&afs_xdnlc);
352 * Remove anything pertaining to this directory. I can invalidate
353 * things without the lock, since I am just looking through the array,
354 * but to move things off the lists or into the freelist, I need the
357 * \param adp vcache entry for the directory to be purged.
361 osi_dnlc_purgedp(struct vcache *adp)
366 #ifdef AFS_DARWIN_ENV
367 if (!(adp->f.states & (CVInit | CVFlushed
368 #ifdef AFS_DARWIN80_ENV
372 cache_purge(AFSTOV(adp));
379 TRACE(osi_dnlc_purgedpT, 0);
380 writelocked = (0 == NBObtainWriteLock(&afs_xdnlc, 2));
382 for (i = 0; i < NCSIZE; i++) {
383 if ((nameCache[i].dirp == adp) || (nameCache[i].vp == adp)) {
384 nameCache[i].dirp = nameCache[i].vp = NULL;
385 if (writelocked && nameCache[i].prev) {
386 RemoveEntry(&nameCache[i], nameCache[i].key & (NHSIZE - 1));
387 nameCache[i].next = ncfreelist;
388 ncfreelist = &nameCache[i];
393 ReleaseWriteLock(&afs_xdnlc);
399 * Remove anything pertaining to this file
401 * \param File vcache entry.
405 osi_dnlc_purgevp(struct vcache *avc)
410 #ifdef AFS_DARWIN_ENV
411 if (!(avc->f.states & (CVInit | CVFlushed
412 #ifdef AFS_DARWIN80_ENV
416 cache_purge(AFSTOV(avc));
423 TRACE(osi_dnlc_purgevpT, 0);
424 writelocked = (0 == NBObtainWriteLock(&afs_xdnlc, 3));
426 for (i = 0; i < NCSIZE; i++) {
427 if (nameCache[i].vp == avc) {
428 nameCache[i].dirp = nameCache[i].vp = NULL;
429 /* can't simply break; because of hard links -- might be two */
430 /* different entries with same vnode */
431 if (writelocked && nameCache[i].prev) {
432 RemoveEntry(&nameCache[i], nameCache[i].key & (NHSIZE - 1));
433 nameCache[i].next = ncfreelist;
434 ncfreelist = &nameCache[i];
439 ReleaseWriteLock(&afs_xdnlc);
444 /* remove everything */
451 TRACE(osi_dnlc_purgeT, 0);
452 if (EWOULDBLOCK == NBObtainWriteLock(&afs_xdnlc, 4)) { /* couldn't get lock */
453 for (i = 0; i < NCSIZE; i++)
454 nameCache[i].dirp = nameCache[i].vp = NULL;
455 } else { /* did get the lock */
457 memset(nameCache, 0, sizeof(struct nc) * NCSIZE);
458 memset(nameHash, 0, sizeof(struct nc *) * NHSIZE);
459 for (i = 0; i < NCSIZE; i++) {
460 nameCache[i].next = ncfreelist;
461 ncfreelist = &nameCache[i];
463 ReleaseWriteLock(&afs_xdnlc);
469 /* remove everything referencing a specific volume */
471 osi_dnlc_purgevol(struct VenusFid *fidp)
474 dnlcstats.purgevols++;
485 Lock_Init(&afs_xdnlc);
486 memset(&dnlcstats, 0, sizeof(dnlcstats));
487 memset(dnlctracetable, 0, sizeof(dnlctracetable));
489 ObtainWriteLock(&afs_xdnlc, 223);
491 memset(nameCache, 0, sizeof(struct nc) * NCSIZE);
492 memset(nameHash, 0, sizeof(struct nc *) * NHSIZE);
493 for (i = 0; i < NCSIZE; i++) {
494 nameCache[i].next = ncfreelist;
495 ncfreelist = &nameCache[i];
497 ReleaseWriteLock(&afs_xdnlc);
503 osi_dnlc_shutdown(void)