diff options
Diffstat (limited to 'erts')
| -rw-r--r-- | erts/emulator/beam/erl_db_hash.c | 60 |
1 files changed, 37 insertions, 23 deletions
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c index 81b0c4465c..98a2e2842a 100644 --- a/erts/emulator/beam/erl_db_hash.c +++ b/erts/emulator/beam/erl_db_hash.c @@ -148,8 +148,11 @@ static ERTS_INLINE Uint hash_to_ix(DbTableHash* tb, HashValue hval) } /* Remember a slot containing a pseudo-deleted item (INVALID_HASH) -*/ -static ERTS_INLINE void add_fixed_deletion(DbTableHash* tb, int ix) + * Return false if we got raced by unfixing thread + * and the object should be deleted for real. + */ +static ERTS_INLINE int add_fixed_deletion(DbTableHash* tb, int ix, + erts_aint_t fixated_by_me) { erts_aint_t was_next; erts_aint_t exp_next; @@ -160,12 +163,18 @@ static ERTS_INLINE void add_fixed_deletion(DbTableHash* tb, int ix) fixd->slot = ix; was_next = erts_smp_atomic_read_acqb(&tb->fixdel); do { /* Lockless atomic insertion in linked list: */ - exp_next = was_next; + if (NFIXED(tb) <= fixated_by_me) { + erts_db_free(ERTS_ALC_T_DB_FIX_DEL, (DbTable*)tb, + fixd, sizeof(FixedDeletion)); + return 0; /* raced by unfixer */ + } + exp_next = was_next; fixd->next = (FixedDeletion*) exp_next; - was_next = erts_smp_atomic_cmpxchg_relb(&tb->fixdel, - (erts_aint_t) fixd, - exp_next); + was_next = erts_smp_atomic_cmpxchg_mb(&tb->fixdel, + (erts_aint_t) fixd, + exp_next); }while (was_next != exp_next); + return 1; } @@ -607,8 +616,8 @@ void db_unfix_table_hash(DbTableHash *tb) || (erts_smp_lc_rwmtx_is_rlocked(&tb->common.rwlock) && !tb->common.is_thread_safe)); restart: - fixdel = (FixedDeletion*) erts_smp_atomic_xchg_acqb(&tb->fixdel, - (erts_aint_t) NULL); + fixdel = (FixedDeletion*) erts_smp_atomic_xchg_mb(&tb->fixdel, + (erts_aint_t) NULL); while (fixdel != NULL) { FixedDeletion *fx = fixdel; int ix = fx->slot; @@ -1142,9 +1151,9 @@ int db_erase_hash(DbTable *tbl, Eterm key, Eterm *ret) while(b != 0) { if (has_live_key(tb,b,key,hval)) { --nitems_diff; - if (nitems_diff == -1 && IS_FIXED(tb)) { + if (nitems_diff == -1 && IS_FIXED(tb) + && add_fixed_deletion(tb, ix, 0)) { /* Pseudo remove (no need to keep several of same key) */ - add_fixed_deletion(tb, ix); b->hvalue = INVALID_HASH; } else { *bp = b->next; @@ -1196,9 +1205,8 @@ static int db_erase_object_hash(DbTable *tbl, Eterm object, Eterm *ret) ++nkeys; if (db_eq(&tb->common,object, &b->dbterm)) { --nitems_diff; - if (nkeys==1 && IS_FIXED(tb)) { /* Pseudo remove */ - add_fixed_deletion(tb,ix); - b->hvalue = INVALID_HASH; + if (nkeys==1 && IS_FIXED(tb) && add_fixed_deletion(tb,ix,0)) { + b->hvalue = INVALID_HASH; /* Pseudo remove */ bp = &b->next; b = b->next; } else { @@ -1820,14 +1828,17 @@ static int db_select_delete_hash(Process *p, int did_erase = 0; if (db_match_dbterm(&tb->common, p, mpi.mp, 0, &(*current)->dbterm, NULL, 0) == am_true) { + HashDbTerm *del; if (NFIXED(tb) > fixated_by_me) { /* fixated by others? */ if (slot_ix != last_pseudo_delete) { - add_fixed_deletion(tb, slot_ix); - last_pseudo_delete = slot_ix; + if (!add_fixed_deletion(tb, slot_ix, fixated_by_me)) + goto do_erase; + last_pseudo_delete = slot_ix; } (*current)->hvalue = INVALID_HASH; } else { - HashDbTerm *del = *current; + do_erase: + del = *current; *current = (*current)->next; free_term(tb, del); did_erase = 1; @@ -1931,14 +1942,17 @@ static int db_select_delete_continue_hash(Process *p, int did_erase = 0; if (db_match_dbterm(&tb->common, p, mp, 0, &(*current)->dbterm, NULL, 0) == am_true) { + HashDbTerm *del; if (NFIXED(tb) > fixated_by_me) { /* fixated by others? */ if (slot_ix != last_pseudo_delete) { - add_fixed_deletion(tb, slot_ix); + if (!add_fixed_deletion(tb, slot_ix, fixated_by_me)) + goto do_erase; last_pseudo_delete = slot_ix; } (*current)->hvalue = INVALID_HASH; } else { - HashDbTerm *del = *current; + do_erase: + del = *current; *current = (*current)->next; free_term(tb, del); did_erase = 1; @@ -2089,9 +2103,9 @@ static int db_take_hash(Process *p, DbTable *tbl, Eterm key, Eterm *ret) *ret = get_term_list(p, tb, key, hval, b, &bend); while (b != bend) { --nitems_diff; - if (nitems_diff == -1 && IS_FIXED(tb)) { + if (nitems_diff == -1 && IS_FIXED(tb) + && add_fixed_deletion(tb, ix, 0)) { /* Pseudo remove (no need to keep several of same key) */ - add_fixed_deletion(tb, ix); bp = &b->next; b->hvalue = INVALID_HASH; b = b->next; @@ -2131,7 +2145,7 @@ int db_mark_all_deleted_hash(DbTable *tbl) for (i = 0; i < NACTIVE(tb); i++) { if ((list = BUCKET(tb,i)) != NULL) { - add_fixed_deletion(tb, i); + add_fixed_deletion(tb, i, 0); do { list->hvalue = INVALID_HASH; list = list->next; @@ -2908,8 +2922,8 @@ db_finalize_dbterm_hash(int cret, DbUpdateHandle* handle) ASSERT((&b->dbterm == handle->dbterm) == !(tb->common.compress && handle->flags & DB_MUST_RESIZE)); if (handle->flags & DB_NEW_OBJECT && cret != DB_ERROR_NONE) { - if (IS_FIXED(tb)) { - add_fixed_deletion(tb, hash_to_ix(tb, b->hvalue)); + if (IS_FIXED(tb) && add_fixed_deletion(tb, hash_to_ix(tb, b->hvalue), + 0)) { b->hvalue = INVALID_HASH; } else { *bp = b->next; |