mirror of
https://git.openldap.org/openldap/openldap.git
synced 2025-12-26 09:39:45 -05:00
Tweak locks, fix race conditions
This commit is contained in:
Howard Chu
parent
d27a7754f3
commit
f7aa0d5e4a
1 changed files with 85 additions and 46 deletions
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@ -91,6 +91,32 @@ typedef ULONG pgno_t;
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#define DKEY(x)
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#endif
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/* The DB view is always consistent because all writes are wrapped in
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* the wmutex. Finer-grained locks aren't necessary.
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*/
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#ifndef LAZY_LOCKS
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#define LAZY_LOCKS 1
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#endif
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#if LAZY_LOCKS
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#define LAZY_MUTEX_LOCK(x)
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#define LAZY_MUTEX_UNLOCK(x)
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#define LAZY_RWLOCK_UNLOCK(x)
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#define LAZY_RWLOCK_WRLOCK(x)
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#define LAZY_RWLOCK_RDLOCK(x)
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#define LAZY_RWLOCK_DEF(x)
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#define LAZY_RWLOCK_INIT(x,y)
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#define LAZY_RWLOCK_DESTROY(x)
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#else
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#define LAZY_MUTEX_LOCK(x) pthread_mutex_lock(x)
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#define LAZY_MUTEX_UNLOCK(x) pthread_mutex_unlock(x)
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#define LAZY_RWLOCK_UNLOCK(x) pthread_rwlock_unlock(x)
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#define LAZY_RWLOCK_WRLOCK(x) pthread_rwlock_wrlock(x)
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#define LAZY_RWLOCK_RDLOCK(x) pthread_rwlock_rdlock(x)
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#define LAZY_RWLOCK_DEF(x) pthread_rwlock_t x
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#define LAZY_RWLOCK_INIT(x,y) pthread_rwlock_init(x,y)
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#define LAZY_RWLOCK_DESTROY(x) pthread_rwlock_destroy(x)
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#endif
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#define P_INVALID (~0UL)
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#define F_ISSET(w, f) (((w) & (f)) == (f))
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@ -308,8 +334,8 @@ struct MDB_txn {
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#define MDB_TXN_RDONLY 0x01 /* read-only transaction */
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#define MDB_TXN_ERROR 0x02 /* an error has occurred */
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#define MDB_TXN_METOGGLE 0x04 /* used meta page 1 */
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unsigned int mt_flags;
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unsigned int mt_toggle;
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};
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/* Context for sorted-dup records */
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@ -334,7 +360,6 @@ struct MDB_env {
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char *me_map;
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MDB_txninfo *me_txns;
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MDB_meta *me_metas[2];
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MDB_meta *me_meta;
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MDB_txn *me_txn; /* current write transaction */
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size_t me_mapsize;
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off_t me_size; /* current file size */
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@ -348,6 +373,7 @@ struct MDB_env {
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MDB_dpage *me_dpages;
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pgno_t me_free_pgs[MDB_IDL_UM_SIZE];
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MIDL2 me_dirty_list[MDB_IDL_DB_SIZE];
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LAZY_RWLOCK_DEF(me_dblock);
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};
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#define NODESIZE offsetof(MDB_node, mn_data)
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@ -714,8 +740,6 @@ mdb_txn_renew0(MDB_txn *txn)
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{
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MDB_env *env = txn->mt_env;
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int rc, toggle;
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if (env->me_flags & MDB_FATAL_ERROR) {
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DPUTS("mdb_txn_begin: environment had fatal error, must shutdown!");
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return MDB_PANIC;
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@ -725,6 +749,9 @@ mdb_txn_renew0(MDB_txn *txn)
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MDB_reader *r = pthread_getspecific(env->me_txkey);
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if (!r) {
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unsigned int i;
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pid_t pid = getpid();
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pthread_t tid = pthread_self();
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pthread_mutex_lock(&env->me_txns->mti_mutex);
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for (i=0; i<env->me_txns->mti_numreaders; i++)
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if (env->me_txns->mti_readers[i].mr_pid == 0)
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@ -733,47 +760,40 @@ mdb_txn_renew0(MDB_txn *txn)
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pthread_mutex_unlock(&env->me_txns->mti_mutex);
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return ENOSPC;
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}
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env->me_txns->mti_readers[i].mr_pid = getpid();
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env->me_txns->mti_readers[i].mr_tid = pthread_self();
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r = &env->me_txns->mti_readers[i];
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pthread_setspecific(env->me_txkey, r);
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env->me_txns->mti_readers[i].mr_pid = pid;
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env->me_txns->mti_readers[i].mr_tid = tid;
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if (i >= env->me_txns->mti_numreaders)
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env->me_txns->mti_numreaders = i+1;
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pthread_mutex_unlock(&env->me_txns->mti_mutex);
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r = &env->me_txns->mti_readers[i];
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pthread_setspecific(env->me_txkey, r);
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}
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txn->mt_txnid = env->me_txns->mti_txnid;
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txn->mt_toggle = env->me_txns->mti_me_toggle;
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r->mr_txnid = txn->mt_txnid;
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txn->mt_u.reader = r;
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} else {
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pthread_mutex_lock(&env->me_txns->mti_wmutex);
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txn->mt_txnid = env->me_txns->mti_txnid+1;
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txn->mt_toggle = env->me_txns->mti_me_toggle;
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txn->mt_u.dirty_list = env->me_dirty_list;
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txn->mt_u.dirty_list[0].mid = 0;
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txn->mt_free_pgs = env->me_free_pgs;
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txn->mt_free_pgs[0] = 0;
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txn->mt_next_pgno = env->me_metas[txn->mt_toggle]->mm_last_pg+1;
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env->me_txn = txn;
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}
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toggle = env->me_txns->mti_me_toggle;
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if ((rc = mdb_env_read_meta(env, &toggle)) != MDB_SUCCESS) {
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mdb_txn_reset0(txn);
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return rc;
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}
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/* Copy the DB arrays */
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LAZY_RWLOCK_RDLOCK(&env->me_dblock);
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txn->mt_numdbs = env->me_numdbs;
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txn->mt_dbxs = env->me_dbxs; /* mostly static anyway */
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memcpy(txn->mt_dbs, env->me_meta->mm_dbs, 2 * sizeof(MDB_db));
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memcpy(txn->mt_dbs, env->me_metas[txn->mt_toggle]->mm_dbs, 2 * sizeof(MDB_db));
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if (txn->mt_numdbs > 2)
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memcpy(txn->mt_dbs+2, env->me_dbs[env->me_db_toggle]+2,
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(txn->mt_numdbs - 2) * sizeof(MDB_db));
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if (!(txn->mt_flags & MDB_TXN_RDONLY)) {
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if (toggle)
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txn->mt_flags |= MDB_TXN_METOGGLE;
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txn->mt_next_pgno = env->me_meta->mm_last_pg+1;
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}
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LAZY_RWLOCK_UNLOCK(&env->me_dblock);
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DPRINTF("begin txn %p %lu%c on mdbenv %p, root page %lu", txn,
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txn->mt_txnid, (txn->mt_flags & MDB_TXN_RDONLY) ? 'r' : 'w',
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@ -1075,16 +1095,21 @@ mdb_txn_commit(MDB_txn *txn)
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return n;
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}
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env->me_txns->mti_txnid = txn->mt_txnid;
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done:
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env->me_txn = NULL;
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/* update the DB tables */
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{
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int toggle = !env->me_db_toggle;
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MDB_db *ip, *jp;
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for (i = 2; i < txn->mt_numdbs; i++)
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env->me_dbs[toggle][i] = txn->mt_dbs[i];
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ip = &env->me_dbs[toggle][2];
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jp = &txn->mt_dbs[2];
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LAZY_RWLOCK_WRLOCK(&env->me_dblock);
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for (i = 2; i < txn->mt_numdbs; i++) {
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if (ip->md_root != jp->md_root)
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*ip = *jp;
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ip++; jp++;
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}
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for (i = 2; i < txn->mt_numdbs; i++) {
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if (txn->mt_dbxs[i].md_dirty)
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@ -1092,6 +1117,7 @@ done:
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}
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env->me_db_toggle = toggle;
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env->me_numdbs = txn->mt_numdbs;
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LAZY_RWLOCK_UNLOCK(&env->me_dblock);
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}
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pthread_mutex_unlock(&env->me_txns->mti_wmutex);
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@ -1197,7 +1223,7 @@ mdb_env_write_meta(MDB_txn *txn)
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assert(txn != NULL);
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assert(txn->mt_env != NULL);
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toggle = !F_ISSET(txn->mt_flags, MDB_TXN_METOGGLE);
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toggle = !txn->mt_toggle;
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DPRINTF("writing meta page %d for root page %lu",
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toggle, txn->mt_dbs[MAIN_DBI].md_root);
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@ -1236,7 +1262,16 @@ mdb_env_write_meta(MDB_txn *txn)
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env->me_flags |= MDB_FATAL_ERROR;
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return rc;
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}
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/* Memory ordering issues are irrelevant; since the entire writer
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* is wrapped by wmutex, all of these changes will become visible
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* after the wmutex is unlocked. Since the DB is multi-version,
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* readers will get consistent data regardless of how fresh or
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* how stale their view of these values is.
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*/
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LAZY_MUTEX_LOCK(&env->me_txns->mti_mutex);
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txn->mt_env->me_txns->mti_me_toggle = toggle;
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txn->mt_env->me_txns->mti_txnid = txn->mt_txnid;
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LAZY_MUTEX_UNLOCK(&env->me_txns->mti_mutex);
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return MDB_SUCCESS;
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}
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@ -1248,15 +1283,11 @@ mdb_env_read_meta(MDB_env *env, int *which)
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assert(env != NULL);
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if (which)
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toggle = *which;
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else if (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid)
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if (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid)
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toggle = 1;
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if (env->me_meta != env->me_metas[toggle])
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env->me_meta = env->me_metas[toggle];
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DPRINTF("Using meta page %d", toggle);
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*which = toggle;
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return MDB_SUCCESS;
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}
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@ -1313,7 +1344,7 @@ mdb_env_get_maxreaders(MDB_env *env, int *readers)
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static int
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mdb_env_open2(MDB_env *env, unsigned int flags)
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{
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int i, newenv = 0;
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int i, newenv = 0, toggle;
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MDB_meta meta;
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MDB_page *p;
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@ -1358,17 +1389,17 @@ mdb_env_open2(MDB_env *env, unsigned int flags)
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env->me_metas[0] = METADATA(p);
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env->me_metas[1] = (MDB_meta *)((char *)env->me_metas[0] + meta.mm_psize);
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if ((i = mdb_env_read_meta(env, NULL)) != 0)
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if ((i = mdb_env_read_meta(env, &toggle)) != 0)
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return i;
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DPRINTF("opened database version %u, pagesize %u",
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env->me_meta->mm_version, env->me_psize);
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DPRINTF("depth: %u", env->me_meta->mm_dbs[MAIN_DBI].md_depth);
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DPRINTF("entries: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_entries);
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DPRINTF("branch pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_branch_pages);
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DPRINTF("leaf pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_leaf_pages);
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DPRINTF("overflow pages: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_overflow_pages);
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DPRINTF("root: %lu", env->me_meta->mm_dbs[MAIN_DBI].md_root);
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env->me_metas[toggle]->mm_version, env->me_psize);
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DPRINTF("depth: %u", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_depth);
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DPRINTF("entries: %lu", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_entries);
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DPRINTF("branch pages: %lu", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_branch_pages);
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DPRINTF("leaf pages: %lu", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_leaf_pages);
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DPRINTF("overflow pages: %lu", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_overflow_pages);
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DPRINTF("root: %lu", env->me_metas[toggle]->mm_dbs[MAIN_DBI].md_root);
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return MDB_SUCCESS;
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}
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@ -1388,10 +1419,12 @@ static void
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mdb_env_share_locks(MDB_env *env)
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{
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struct flock lock_info;
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int toggle = 0;
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env->me_txns->mti_txnid = env->me_meta->mm_txnid;
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if (env->me_metas[0]->mm_txnid < env->me_metas[1]->mm_txnid)
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env->me_txns->mti_me_toggle = 1;
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toggle = 1;
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env->me_txns->mti_me_toggle = toggle;
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env->me_txns->mti_txnid = env->me_metas[toggle]->mm_txnid;
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memset((void *)&lock_info, 0, sizeof(lock_info));
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lock_info.l_type = F_RDLCK;
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@ -1535,6 +1568,7 @@ mdb_env_open(MDB_env *env, const char *path, unsigned int flags, mode_t mode)
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env->me_path = strdup(path);
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DPRINTF("opened dbenv %p", (void *) env);
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pthread_key_create(&env->me_txkey, mdb_env_reader_dest);
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LAZY_RWLOCK_INIT(&env->me_dblock, NULL);
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if (excl)
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mdb_env_share_locks(env);
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env->me_dbxs = calloc(env->me_maxdbs, sizeof(MDB_dbx));
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@ -1577,6 +1611,7 @@ mdb_env_close(MDB_env *env)
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free(env->me_dbxs);
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free(env->me_path);
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LAZY_RWLOCK_DESTROY(&env->me_dblock);
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pthread_key_delete(env->me_txkey);
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if (env->me_map) {
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@ -1587,7 +1622,7 @@ mdb_env_close(MDB_env *env)
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if (env->me_txns) {
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pid_t pid = getpid();
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size_t size = (env->me_maxreaders-1) * sizeof(MDB_reader) + sizeof(MDB_txninfo);
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int i;
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unsigned int i;
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for (i=0; i<env->me_txns->mti_numreaders; i++)
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if (env->me_txns->mti_readers[i].mr_pid == pid)
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env->me_txns->mti_readers[i].mr_pid = 0;
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@ -1718,7 +1753,7 @@ mdb_get_page(MDB_txn *txn, pgno_t pgno, MDB_page **ret)
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}
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}
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if (!p) {
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if (pgno <= txn->mt_env->me_meta->mm_last_pg)
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if (pgno <= txn->mt_env->me_metas[txn->mt_toggle]->mm_last_pg)
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p = (MDB_page *)(txn->mt_env->me_map + txn->mt_env->me_psize * pgno);
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}
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*ret = p;
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@ -3674,10 +3709,14 @@ mdb_stat0(MDB_env *env, MDB_db *db, MDB_stat *arg)
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int
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mdb_env_stat(MDB_env *env, MDB_stat *arg)
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{
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int toggle;
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if (env == NULL || arg == NULL)
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return EINVAL;
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return mdb_stat0(env, &env->me_meta->mm_dbs[MAIN_DBI], arg);
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mdb_env_read_meta(env, &toggle);
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return mdb_stat0(env, &env->me_metas[toggle]->mm_dbs[MAIN_DBI], arg);
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}
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int mdb_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
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