diff options
Diffstat (limited to 'servers/slapd/overlays/seqmod.c')
| -rw-r--r-- | servers/slapd/overlays/seqmod.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/servers/slapd/overlays/seqmod.c b/servers/slapd/overlays/seqmod.c new file mode 100644 index 0000000..e6ff9fb --- /dev/null +++ b/servers/slapd/overlays/seqmod.c @@ -0,0 +1,206 @@ +/* seqmod.c - sequenced modifies */ +/* This work is part of OpenLDAP Software <http://www.openldap.org/>. + * + * Copyright 2004-2021 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>. + */ +/* ACKNOWLEDGEMENTS: + * This work was initially developed by Howard Chu for inclusion in + * OpenLDAP Software. + */ + +#include "portable.h" + +#ifdef SLAPD_OVER_SEQMOD + +#include "slap.h" +#include "config.h" + +/* This overlay serializes concurrent attempts to modify a single entry */ + +typedef struct modtarget { + struct modtarget *mt_next; + struct modtarget *mt_tail; + Operation *mt_op; +} modtarget; + +typedef struct seqmod_info { + Avlnode *sm_mods; /* entries being modified */ + ldap_pvt_thread_mutex_t sm_mutex; +} seqmod_info; + +static int +sm_avl_cmp( const void *c1, const void *c2 ) +{ + const modtarget *m1, *m2; + int rc; + + m1 = c1; m2 = c2; + rc = m1->mt_op->o_req_ndn.bv_len - m2->mt_op->o_req_ndn.bv_len; + + if ( rc ) return rc; + return ber_bvcmp( &m1->mt_op->o_req_ndn, &m2->mt_op->o_req_ndn ); +} + +static int +seqmod_op_cleanup( Operation *op, SlapReply *rs ) +{ + slap_callback *sc = op->o_callback; + seqmod_info *sm = sc->sc_private; + modtarget *mt, mtdummy; + Avlnode *av; + + mtdummy.mt_op = op; + /* This op is done, remove it */ + ldap_pvt_thread_mutex_lock( &sm->sm_mutex ); + av = avl_find2( sm->sm_mods, &mtdummy, sm_avl_cmp ); + assert(av != NULL); + + mt = av->avl_data; + + /* If there are more, promote the next one */ + if ( mt->mt_next ) { + av->avl_data = mt->mt_next; + mt->mt_next->mt_tail = mt->mt_tail; + } else { + avl_delete( &sm->sm_mods, mt, sm_avl_cmp ); + } + ldap_pvt_thread_mutex_unlock( &sm->sm_mutex ); + op->o_callback = sc->sc_next; + op->o_tmpfree( sc, op->o_tmpmemctx ); + + return 0; +} + +static int +seqmod_op_mod( Operation *op, SlapReply *rs ) +{ + slap_overinst *on = (slap_overinst *)op->o_bd->bd_info; + seqmod_info *sm = on->on_bi.bi_private; + modtarget *mt; + Avlnode *av; + slap_callback *cb; + + cb = op->o_tmpcalloc( 1, sizeof(slap_callback) + sizeof(modtarget), + op->o_tmpmemctx ); + mt = (modtarget *)(cb+1); + mt->mt_next = NULL; + mt->mt_tail = mt; + mt->mt_op = op; + + /* See if we're already modifying this entry - don't allow + * near-simultaneous mods of the same entry + */ + ldap_pvt_thread_mutex_lock( &sm->sm_mutex ); + av = avl_find2( sm->sm_mods, mt, sm_avl_cmp ); + if ( av ) { + modtarget *mtp = av->avl_data; + mtp->mt_tail->mt_next = mt; + mtp->mt_tail = mt; + /* Wait for this op to get to head of list */ + while ( mtp != mt ) { + ldap_pvt_thread_mutex_unlock( &sm->sm_mutex ); + ldap_pvt_thread_yield(); + /* Let it finish - should use a condition + * variable here... */ + ldap_pvt_thread_mutex_lock( &sm->sm_mutex ); + mtp = av->avl_data; + } + } else { + /* Record that we're modifying this now */ + avl_insert( &sm->sm_mods, mt, sm_avl_cmp, avl_dup_error ); + } + ldap_pvt_thread_mutex_unlock( &sm->sm_mutex ); + + cb->sc_cleanup = seqmod_op_cleanup; + cb->sc_private = sm; + cb->sc_next = op->o_callback; + op->o_callback = cb; + + return SLAP_CB_CONTINUE; +} + +static int +seqmod_op_extended( + Operation *op, + SlapReply *rs +) +{ + if ( exop_is_write( op )) return seqmod_op_mod( op, rs ); + else return SLAP_CB_CONTINUE; +} + +static int +seqmod_db_open( + BackendDB *be, + ConfigReply *cr +) +{ + slap_overinst *on = (slap_overinst *)be->bd_info; + seqmod_info *sm; + + sm = ch_calloc(1, sizeof(seqmod_info)); + on->on_bi.bi_private = sm; + + ldap_pvt_thread_mutex_init( &sm->sm_mutex ); + + return 0; +} + +static int +seqmod_db_close( + BackendDB *be, + ConfigReply *cr +) +{ + slap_overinst *on = (slap_overinst *)be->bd_info; + seqmod_info *sm = (seqmod_info *)on->on_bi.bi_private; + + if ( sm ) { + ldap_pvt_thread_mutex_destroy( &sm->sm_mutex ); + + ch_free( sm ); + on->on_bi.bi_private = NULL; + } + + return 0; +} + +/* This overlay is set up for dynamic loading via moduleload. For static + * configuration, you'll need to arrange for the slap_overinst to be + * initialized and registered by some other function inside slapd. + */ + +static slap_overinst seqmod; + +int +seqmod_initialize() +{ + seqmod.on_bi.bi_type = "seqmod"; + seqmod.on_bi.bi_db_open = seqmod_db_open; + seqmod.on_bi.bi_db_close = seqmod_db_close; + + seqmod.on_bi.bi_op_modify = seqmod_op_mod; + seqmod.on_bi.bi_op_modrdn = seqmod_op_mod; + seqmod.on_bi.bi_extended = seqmod_op_extended; + + return overlay_register( &seqmod ); +} + +#if SLAPD_OVER_SEQMOD == SLAPD_MOD_DYNAMIC +int +init_module( int argc, char *argv[] ) +{ + return seqmod_initialize(); +} +#endif /* SLAPD_OVER_SEQMOD == SLAPD_MOD_DYNAMIC */ + +#endif /* defined(SLAPD_OVER_SEQMOD) */ |