openldap/servers/slapd/back-ldbm/cache.c

672 lines
15 KiB
C

/* cache.c - routines to maintain an in-core cache of entries */
/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
* Copyright 1998-2005 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in the file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*/
#include "portable.h"
#include <stdio.h>
#include <ac/errno.h>
#include <ac/string.h>
#include <ac/socket.h>
#include "slap.h"
#include "back-ldbm.h"
/* LDBM backend specific entry info -- visible only to the cache */
typedef struct ldbm_entry_info {
/*
* These items are specific to the LDBM backend and should
* be hidden. Backend cache lock required to access.
*/
int lei_state; /* for the cache */
#define CACHE_ENTRY_UNDEFINED 0
#define CACHE_ENTRY_CREATING 1
#define CACHE_ENTRY_READY 2
#define CACHE_ENTRY_DELETED 3
#define CACHE_ENTRY_COMMITTED 4
int lei_refcnt; /* # threads ref'ing this entry */
Entry *lei_lrunext; /* for cache lru list */
Entry *lei_lruprev;
} EntryInfo;
#undef LEI
#define LEI(e) ((EntryInfo *) ((e)->e_private))
static int cache_delete_entry_internal(Cache *cache, Entry *e);
#ifdef LDAP_DEBUG
static void lru_print(Cache *cache);
#endif
static int
cache_entry_private_init( Entry*e )
{
assert( e->e_private == NULL );
if( e->e_private != NULL ) {
/* this should never happen */
return 1;
}
e->e_private = ch_calloc(1, sizeof(struct ldbm_entry_info));
return 0;
}
/*
* marks an entry in CREATING state as committed, so it is really returned
* to the cache. Otherwise an entry in CREATING state is removed.
* Makes e_private be destroyed at the following cache_return_entry_w,
* but lets the entry untouched (owned by someone else)
*/
void
cache_entry_commit( Entry *e )
{
assert( e != NULL );
assert( e->e_private != NULL );
assert( LEI(e)->lei_state == CACHE_ENTRY_CREATING );
/* assert( LEI(e)->lei_refcnt == 1 ); */
LEI(e)->lei_state = CACHE_ENTRY_COMMITTED;
}
static int
cache_entry_private_destroy( Entry*e )
{
assert( e->e_private != NULL );
free( e->e_private );
e->e_private = NULL;
return 0;
}
void
cache_return_entry_rw( Cache *cache, Entry *e, int rw )
{
ID id;
int refcnt, freeit = 1;
if ( slapMode != SLAP_SERVER_MODE ) {
return;
}
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
assert( e->e_private != NULL );
id = e->e_id;
refcnt = --LEI(e)->lei_refcnt;
/*
* if the entry is returned when in CREATING state, it is deleted
* but not freed because it may belong to someone else (do_add,
* for instance)
*/
if ( LEI(e)->lei_state == CACHE_ENTRY_CREATING ) {
cache_delete_entry_internal( cache, e );
freeit = 0;
/* now the entry is in DELETED state */
}
if ( LEI(e)->lei_state == CACHE_ENTRY_COMMITTED ) {
LEI(e)->lei_state = CACHE_ENTRY_READY;
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE,
"====> cache_return_entry_%s( %ld ): created (%d)\n",
rw ? "w" : "r", id, refcnt );
} else if ( LEI(e)->lei_state == CACHE_ENTRY_DELETED ) {
if( refcnt > 0 ) {
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE,
"====> cache_return_entry_%s( %ld ): delete pending (%d)\n",
rw ? "w" : "r", id, refcnt );
} else {
cache_entry_private_destroy( e );
if ( freeit ) {
entry_free( e );
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE,
"====> cache_return_entry_%s( %ld ): deleted (%d)\n",
rw ? "w" : "r", id, refcnt );
}
} else {
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE,
"====> cache_return_entry_%s( %ld ): returned (%d)\n",
rw ? "w" : "r", id, refcnt);
}
}
#define LRU_DELETE( cache, e ) do { \
if ( LEI(e)->lei_lruprev != NULL ) { \
LEI(LEI(e)->lei_lruprev)->lei_lrunext = LEI(e)->lei_lrunext; \
} else { \
(cache)->c_lruhead = LEI(e)->lei_lrunext; \
} \
if ( LEI(e)->lei_lrunext != NULL ) { \
LEI(LEI(e)->lei_lrunext)->lei_lruprev = LEI(e)->lei_lruprev; \
} else { \
(cache)->c_lrutail = LEI(e)->lei_lruprev; \
} \
} while(0)
#define LRU_ADD( cache, e ) do { \
LEI(e)->lei_lrunext = (cache)->c_lruhead; \
if ( LEI(e)->lei_lrunext != NULL ) { \
LEI(LEI(e)->lei_lrunext)->lei_lruprev = (e); \
} \
(cache)->c_lruhead = (e); \
LEI(e)->lei_lruprev = NULL; \
if ( (cache)->c_lrutail == NULL ) { \
(cache)->c_lrutail = (e); \
} \
} while(0)
/*
* cache_add_entry_rw - create and lock an entry in the cache
* returns: 0 entry has been created and locked
* 1 entry already existed
* -1 something bad happened
*/
int
cache_add_entry_rw(
Cache *cache,
Entry *e,
int rw
)
{
int i, rc;
Entry *ee;
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
assert( e->e_private == NULL );
if( cache_entry_private_init(e) != 0 ) {
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_ANY,
"====> cache_add_entry( %ld ): \"%s\": private init failed!\n",
e->e_id, e->e_dn, 0 );
return( -1 );
}
if ( avl_insert( &cache->c_dntree, (caddr_t) e,
entry_dn_cmp, avl_dup_error ) != 0 )
{
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE,
"====> cache_add_entry( %ld ): \"%s\": already in dn cache\n",
e->e_id, e->e_dn, 0 );
cache_entry_private_destroy(e);
return( 1 );
}
/* id tree */
if ( avl_insert( &cache->c_idtree, (caddr_t) e,
entry_id_cmp, avl_dup_error ) != 0 )
{
Debug( LDAP_DEBUG_ANY,
"====> cache_add_entry( %ld ): \"%s\": already in id cache\n",
e->e_id, e->e_dn, 0 );
/* delete from dn tree inserted above */
if ( avl_delete( &cache->c_dntree, (caddr_t) e,
entry_dn_cmp ) == NULL )
{
Debug( LDAP_DEBUG_ANY, "====> can't delete from dn cache\n",
0, 0, 0 );
}
cache_entry_private_destroy(e);
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( -1 );
}
/* put the entry into 'CREATING' state */
/* will be marked after when entry is returned */
LEI(e)->lei_state = CACHE_ENTRY_CREATING;
LEI(e)->lei_refcnt = 1;
/* lru */
LRU_ADD( cache, e );
if ( ++cache->c_cursize > cache->c_maxsize ) {
/*
* find the lru entry not currently in use and delete it.
* in case a lot of entries are in use, only look at the
* first 10 on the tail of the list.
*/
i = 0;
while ( cache->c_lrutail != NULL &&
LEI(cache->c_lrutail)->lei_refcnt != 0 &&
i < 10 )
{
/* move this in-use entry to the front of the q */
ee = cache->c_lrutail;
LRU_DELETE( cache, ee );
LRU_ADD( cache, ee );
i++;
}
/*
* found at least one to delete - try to get back under
* the max cache size.
*/
while ( cache->c_lrutail != NULL &&
LEI(cache->c_lrutail)->lei_refcnt == 0 &&
cache->c_cursize > cache->c_maxsize )
{
e = cache->c_lrutail;
/* delete from cache and lru q */
/* XXX do we need rc ? */
rc = cache_delete_entry_internal( cache, e );
cache_entry_private_destroy( e );
entry_free( e );
}
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( 0 );
}
/*
* cache_update_entry - update a LOCKED entry which has been deleted.
* returns: 0 entry has been created and locked
* 1 entry already existed
* -1 something bad happened
*/
int
cache_update_entry(
Cache *cache,
Entry *e
)
{
int i, rc;
Entry *ee;
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
assert( e->e_private != NULL );
if ( avl_insert( &cache->c_dntree, (caddr_t) e,
entry_dn_cmp, avl_dup_error ) != 0 )
{
Debug( LDAP_DEBUG_TRACE,
"====> cache_update_entry( %ld ): \"%s\": already in dn cache\n",
e->e_id, e->e_dn, 0 );
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( 1 );
}
/* id tree */
if ( avl_insert( &cache->c_idtree, (caddr_t) e,
entry_id_cmp, avl_dup_error ) != 0 )
{
Debug( LDAP_DEBUG_ANY,
"====> cache_update_entry( %ld ): \"%s\": already in id cache\n",
e->e_id, e->e_dn, 0 );
/* delete from dn tree inserted above */
if ( avl_delete( &cache->c_dntree, (caddr_t) e,
entry_dn_cmp ) == NULL )
{
Debug( LDAP_DEBUG_ANY, "====> can't delete from dn cache\n",
0, 0, 0 );
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( -1 );
}
/* put the entry into 'CREATING' state */
/* will be marked after when entry is returned */
LEI(e)->lei_state = CACHE_ENTRY_CREATING;
/* lru */
LRU_ADD( cache, e );
if ( ++cache->c_cursize > cache->c_maxsize ) {
/*
* find the lru entry not currently in use and delete it.
* in case a lot of entries are in use, only look at the
* first 10 on the tail of the list.
*/
i = 0;
while ( cache->c_lrutail != NULL &&
LEI(cache->c_lrutail)->lei_refcnt != 0 &&
i < 10 )
{
/* move this in-use entry to the front of the q */
ee = cache->c_lrutail;
LRU_DELETE( cache, ee );
LRU_ADD( cache, ee );
i++;
}
/*
* found at least one to delete - try to get back under
* the max cache size.
*/
while ( cache->c_lrutail != NULL &&
LEI(cache->c_lrutail)->lei_refcnt == 0 &&
cache->c_cursize > cache->c_maxsize )
{
e = cache->c_lrutail;
/* delete from cache and lru q */
/* XXX do we need rc ? */
rc = cache_delete_entry_internal( cache, e );
cache_entry_private_destroy( e );
entry_free( e );
}
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( 0 );
}
ID
cache_find_entry_ndn2id(
Backend *be,
Cache *cache,
struct berval *ndn
)
{
Entry e, *ep;
ID id;
int count = 0;
/* this function is always called with normalized DN */
e.e_nname = *ndn;
try_again:
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
if ( (ep = (Entry *) avl_find( cache->c_dntree, (caddr_t) &e,
entry_dn_cmp )) != NULL )
{
int state;
count++;
/*
* ep now points to an unlocked entry
* we do not need to lock the entry if we only
* check the state, refcnt, LRU, and id.
*/
assert( ep->e_private != NULL );
/* save id */
id = ep->e_id;
state = LEI(ep)->lei_state;
/*
* entry is deleted or not fully created yet
*/
if ( state != CACHE_ENTRY_READY ) {
assert(state != CACHE_ENTRY_UNDEFINED);
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug(LDAP_DEBUG_TRACE,
"====> cache_find_entry_ndn2id(\"%s\"): %ld (not ready) %d\n",
ndn->bv_val, id, state);
ldap_pvt_thread_yield();
goto try_again;
}
/* lru */
LRU_DELETE( cache, ep );
LRU_ADD( cache, ep );
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug(LDAP_DEBUG_TRACE,
"====> cache_find_entry_ndn2id(\"%s\"): %ld (%d tries)\n",
ndn->bv_val, id, count);
} else {
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
id = NOID;
}
return( id );
}
/*
* cache_find_entry_id - find an entry in the cache, given id
*/
Entry *
cache_find_entry_id(
Cache *cache,
ID id,
int rw
)
{
Entry e;
Entry *ep;
int count = 0;
e.e_id = id;
try_again:
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
if ( (ep = (Entry *) avl_find( cache->c_idtree, (caddr_t) &e,
entry_id_cmp )) != NULL )
{
int state;
ID ep_id;
count++;
assert( ep->e_private != NULL );
ep_id = ep->e_id;
state = LEI(ep)->lei_state;
/*
* entry is deleted or not fully created yet
*/
if ( state != CACHE_ENTRY_READY ) {
assert(state != CACHE_ENTRY_UNDEFINED);
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug(LDAP_DEBUG_TRACE,
"====> cache_find_entry_id( %ld ): %ld (not ready) %d\n",
id, ep_id, state);
ldap_pvt_thread_yield();
goto try_again;
}
/* lru */
LRU_DELETE( cache, ep );
LRU_ADD( cache, ep );
LEI(ep)->lei_refcnt++;
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
Debug(LDAP_DEBUG_TRACE,
"====> cache_find_entry_id( %ld ) \"%s\" (found) (%d tries)\n",
ep_id, ep->e_dn, count);
return( ep );
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( NULL );
}
/*
* cache_delete_entry - delete the entry e from the cache. the caller
* should have obtained e (increasing its ref count) via a call to one
* of the cache_find_* routines. the caller should *not* call the
* cache_return_entry() routine prior to calling cache_delete_entry().
* it performs this function.
*
* returns: 0 e was deleted ok
* 1 e was not in the cache
* -1 something bad happened
*/
int
cache_delete_entry(
Cache *cache,
Entry *e
)
{
int rc;
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
assert( e->e_private != NULL );
Debug( LDAP_DEBUG_TRACE, "====> cache_delete_entry( %ld )\n",
e->e_id, 0, 0 );
rc = cache_delete_entry_internal( cache, e );
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
return( rc );
}
static int
cache_delete_entry_internal(
Cache *cache,
Entry *e
)
{
int rc = 0; /* return code */
/* dn tree */
if ( avl_delete( &cache->c_dntree, (caddr_t) e, entry_dn_cmp ) == NULL )
{
rc = -1;
}
/* id tree */
if ( avl_delete( &cache->c_idtree, (caddr_t) e, entry_id_cmp ) == NULL )
{
rc = -1;
}
if (rc != 0) {
return rc;
}
/* lru */
LRU_DELETE( cache, e );
cache->c_cursize--;
/*
* flag entry to be freed later by a call to cache_return_entry()
*/
LEI(e)->lei_state = CACHE_ENTRY_DELETED;
return( 0 );
}
void
cache_release_all( Cache *cache )
{
Entry *e;
int rc;
/* set cache mutex */
ldap_pvt_thread_mutex_lock( &cache->c_mutex );
Debug( LDAP_DEBUG_TRACE, "====> cache_release_all\n", 0, 0, 0 );
while ( (e = cache->c_lrutail) != NULL && LEI(e)->lei_refcnt == 0 ) {
/* delete from cache and lru q */
/* XXX do we need rc ? */
rc = cache_delete_entry_internal( cache, e );
cache_entry_private_destroy( e );
entry_free( e );
}
if ( cache->c_cursize ) {
Debug( LDAP_DEBUG_TRACE, "Entry-cache could not be emptied\n", 0, 0, 0 );
}
/* free cache mutex */
ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
}
#ifdef LDAP_DEBUG
static void
lru_print( Cache *cache )
{
Entry *e;
fprintf( stderr, "LRU queue (head to tail):\n" );
for ( e = cache->c_lruhead; e != NULL; e = LEI(e)->lei_lrunext ) {
fprintf( stderr, "\tdn \"%20s\" id %ld refcnt %d\n",
e->e_dn, e->e_id, LEI(e)->lei_refcnt );
}
fprintf( stderr, "LRU queue (tail to head):\n" );
for ( e = cache->c_lrutail; e != NULL; e = LEI(e)->lei_lruprev ) {
fprintf( stderr, "\tdn \"%20s\" id %ld refcnt %d\n",
e->e_dn, e->e_id, LEI(e)->lei_refcnt );
}
}
#endif