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Bug hunting -- various problems with opening caches.

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This commit is contained in:
Mark Valence 2000-06-14 18:23:43 +00:00
parent 0ebf86f2d3
commit 89da861b89
2 changed files with 78 additions and 48 deletions
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1
servers/slapd/back-ldbm/back-ldbm.h
View File

@ -92,6 +92,7 @@ typedef struct ldbm_dbcache {
int dbc_maxids;
int dbc_maxindirect;
int dbc_dirty;
int dbc_flags;
time_t dbc_lastref;
long dbc_blksize;
char *dbc_name;

125
servers/slapd/back-ldbm/dbcache.c
View File

@ -27,7 +27,7 @@ ldbm_cache_open(
)
{
struct ldbminfo *li = (struct ldbminfo *) be->be_private;
int i, lru;
int i, lru, empty;
time_t oldtime, curtime;
char buf[MAXPATHLEN];
#ifdef HAVE_ST_BLKSIZE
@ -52,58 +52,84 @@ ldbm_cache_open(
Debug( LDAP_DEBUG_TRACE, "=> ldbm_cache_open( \"%s\", %d, %o )\n", buf,
flags, li->li_mode );
lru = 0;
curtime = slap_get_time();
oldtime = curtime;
empty = MAXDBCACHE;
ldap_pvt_thread_mutex_lock( &li->li_dbcache_mutex );
for ( i = 0; i < MAXDBCACHE && li->li_dbcache[i].dbc_name != NULL;
i++ ) {
/* already open - return it */
if ( strcmp( li->li_dbcache[i].dbc_name, buf ) == 0 ) {
li->li_dbcache[i].dbc_refcnt++;
Debug( LDAP_DEBUG_TRACE,
"<= ldbm_cache_open (cache %d)\n", i, 0, 0 );
ldap_pvt_thread_mutex_unlock( &li->li_dbcache_mutex );
return( &li->li_dbcache[i] );
}
/* keep track of lru db */
if ( li->li_dbcache[i].dbc_lastref < oldtime &&
li->li_dbcache[i].dbc_refcnt == 0 ) {
lru = i;
oldtime = li->li_dbcache[i].dbc_lastref;
}
}
/* no empty slots, not already open - close lru and use that slot */
if ( i == MAXDBCACHE ) {
i = lru;
if ( li->li_dbcache[i].dbc_refcnt != 0 ) {
Debug( LDAP_DEBUG_ANY,
"ldbm_cache_open no unused db to close - waiting\n",
0, 0, 0 );
lru = -1;
while ( lru == -1 ) {
ldap_pvt_thread_cond_wait( &li->li_dbcache_cv,
&li->li_dbcache_mutex );
for ( i = 0; i < MAXDBCACHE; i++ ) {
if ( li->li_dbcache[i].dbc_refcnt
== 0 ) {
lru = i;
break;
}
}
do {
lru = 0;
oldtime = curtime;
for ( i = 0; i < MAXDBCACHE; i++ ) {
/* see if this slot is free */
if ( li->li_dbcache[i].dbc_name == NULL) {
empty = i;
continue;
}
if ( strcmp( li->li_dbcache[i].dbc_name, buf ) == 0 ) {
/* already open - return it */
if (li->li_dbcache[i].dbc_flags != flags
&& li->li_dbcache[i].dbc_refcnt == 0)
{
/* we don't want to use an open cache with different
* permissions (esp. if we need write but the open
* cache is read-only). So close this one if
* possible, and re-open below.
*
* FIXME: what about the case where the refcount
* is > 0? right now, we're using it anyway and
* just praying. Can there be more than one open
* cache to the same db?
*
* Also, it's really only necessary to compare the
* read-only flag, instead of all of the flags,
* but for now I'm checking all of them.
*/
lru = i;
empty = MAXDBCACHE;
break;
}
li->li_dbcache[i].dbc_refcnt++;
Debug( LDAP_DEBUG_TRACE,
"<= ldbm_cache_open (cache %d)\n", i, 0, 0 );
ldap_pvt_thread_mutex_unlock( &li->li_dbcache_mutex );
return( &li->li_dbcache[i] );
}
/* keep track of lru db */
if ( li->li_dbcache[i].dbc_lastref < oldtime
&& li->li_dbcache[i].dbc_refcnt == 0 )
{
lru = i;
oldtime = li->li_dbcache[i].dbc_lastref;
}
i = lru;
}
ldbm_close( li->li_dbcache[i].dbc_db );
free( li->li_dbcache[i].dbc_name );
li->li_dbcache[i].dbc_name = NULL;
}
i = empty;
if ( i == MAXDBCACHE ) {
/* no empty slots, not already open - close lru and use that slot */
if ( li->li_dbcache[lru].dbc_refcnt == 0 ) {
i = lru;
ldbm_close( li->li_dbcache[i].dbc_db );
free( li->li_dbcache[i].dbc_name );
li->li_dbcache[i].dbc_name = NULL;
} else {
Debug( LDAP_DEBUG_ANY,
"ldbm_cache_open no unused db to close - waiting\n",
0, 0, 0 );
ldap_pvt_thread_cond_wait( &li->li_dbcache_cv,
&li->li_dbcache_mutex );
/* after waiting for a free slot, go back to square
* one: look for an open cache for this db, or an
* empty slot, or an unref'ed cache, or wait again.
*/
}
}
} while (i == MAXDBCACHE);
if ( (li->li_dbcache[i].dbc_db = ldbm_open( buf, flags, li->li_mode,
li->li_dbcachesize )) == NULL ) {
li->li_dbcachesize )) == NULL )
{
int err = errno;
Debug( LDAP_DEBUG_TRACE,
"<= ldbm_cache_open NULL \"%s\" errno=%d reason=\"%s\")\n",
@ -115,6 +141,7 @@ ldbm_cache_open(
li->li_dbcache[i].dbc_name = ch_strdup( buf );
li->li_dbcache[i].dbc_refcnt = 1;
li->li_dbcache[i].dbc_lastref = curtime;
li->li_dbcache[i].dbc_flags = flags;
li->li_dbcache[i].dbc_dirty = 0;
#ifdef HAVE_ST_BLKSIZE
if ( stat( buf, &st ) == 0 ) {
@ -151,7 +178,8 @@ ldbm_cache_close( Backend *be, DBCache *db )
}
ldap_pvt_thread_mutex_lock( &li->li_dbcache_mutex );
if ( --db->dbc_refcnt == 0 ) {
if ( --db->dbc_refcnt <= 0 ) {
db->dbc_refcnt = 0;
ldap_pvt_thread_cond_signal( &li->li_dbcache_cv );
}
ldap_pvt_thread_mutex_unlock( &li->li_dbcache_mutex );
@ -163,7 +191,8 @@ ldbm_cache_really_close( Backend *be, DBCache *db )
struct ldbminfo *li = (struct ldbminfo *) be->be_private;
ldap_pvt_thread_mutex_lock( &li->li_dbcache_mutex );
if ( --db->dbc_refcnt == 0 ) {
if ( --db->dbc_refcnt <= 0 ) {
db->dbc_refcnt = 0;
ldap_pvt_thread_cond_signal( &li->li_dbcache_cv );
ldbm_close( db->dbc_db );
free( db->dbc_name );