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author | Sergey Poznyakoff <gray@gnu.org.ua> | 2016-08-25 16:06:58 +0300 |
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committer | Sergey Poznyakoff <gray@gnu.org.ua> | 2016-08-25 16:06:58 +0300 |
commit | c2f02c56a38a3e6d50b8ca2081db9d2de658b8ed (patch) | |
tree | a6c80fd81a6b5aad899d8fb0e3e41ece650eed9b /src/symtab.c | |
parent | 102d1b9c1a94548dfa0c498845c77933db6a7738 (diff) | |
download | grecs-c2f02c56a38a3e6d50b8ca2081db9d2de658b8ed.tar.gz grecs-c2f02c56a38a3e6d50b8ca2081db9d2de658b8ed.tar.bz2 |
symtabs: allow to modify the list during iteration over it.
* include/grecs/list.h (grecs_list_remove): New proto.
* include/grecs/symtab.h (grecs_symtab_count_entries):
Rename to grecs_symtab_count.
* src/list.c (grecs_list_remove): New function.
(grecs_list_remove_tail, grecs_list_clear)
(grecs_list_locate,grecs_list_index): Treat NULL list
as empty list.
* src/symtab.c: Defer table modifications during iteration
(symtab_defer_type): New enum.
(grecs_symtab)<elcount,itr_level,defer_list>: New members.
(symtab_defer_op): New static function.
(grecs_symtab_remove): When called during iteration, add the
entry to the defer_del deferment list, unless it is already
in defer_add, in which case remove it from there.
Update elcount.
(grecs_symtab_lookup_or_install): Defer addition when iterating.
Update elcount.
(grecs_symtab_clear): Reset elcount to 0.
(grecs_symtab_create): Initialize elcount.
(grecs_symtab_foreach): Process deferred modifications.
Diffstat (limited to 'src/symtab.c')
-rw-r--r-- | src/symtab.c | 113 |
1 files changed, 91 insertions, 22 deletions
diff --git a/src/symtab.c b/src/symtab.c index 540ea0f..3647a81 100644 --- a/src/symtab.c +++ b/src/symtab.c @@ -33,16 +33,36 @@ static unsigned int hash_size[] = { /* |max_rehash| keeps the number of entries in |hash_size| table. */ static unsigned int max_rehash = sizeof(hash_size) / sizeof(hash_size[0]); +enum symtab_defer_type { + defer_add, + defer_del +}; + struct grecs_symtab { int flags; - unsigned int hash_num; /* Index to hash_size table */ - size_t elsize; /* Size of an element */ - struct grecs_syment **tab; - unsigned (*hash_fun)(void *, unsigned long hash_num); + unsigned int hash_num; /* Index to hash_size table */ + size_t elsize; /* Size of an element */ + size_t elcount; /* Number of elements in use */ + struct grecs_syment **tab; /* Table of element pointers */ + + /* Functions that can be overridden when creating the symtab: */ + unsigned (*hash_fun)(void *, unsigned long); int (*cmp_fun)(const void *, const void *); int (*copy_fun)(void *, void *); - void *(*syment_alloc_fun)(size_t size); + void *(*syment_alloc_fun)(size_t); void (*syment_free_fun) (void *); + + /* Support for deferred operations. When an insertion or deletion + is requested while the symtab is being iterated over, this operation + is deferred until the iteration is finished. */ + + /* Iteration level. Gets increased upon entry to grecs_symtab_foreach, + and decreased right before leaving it. */ + unsigned int itr_level; + /* Two deferment lists keep track of the deferred additions and + removals: + */ + grecs_list_ptr_t defer_list[2]; }; static void @@ -72,7 +92,17 @@ syment_alloc(struct grecs_symtab *st, void *key) } return ent; } - + +static void +symtab_defer_op(struct grecs_symtab *st, enum symtab_defer_type type, + struct grecs_syment *ent) +{ + if (!st->defer_list[type]) { + st->defer_list[type] = grecs_list_create(); + st->defer_list[type]->cmp = st->cmp_fun; + } + grecs_list_append(st->defer_list[type], ent); +} unsigned grecs_hash_string(const char *name, unsigned long hashsize) @@ -101,8 +131,8 @@ grecs_hash_string_ci(const char *name, unsigned long hashsize) static unsigned def_hash(void *data, unsigned long hashsize) { - struct grecs_syment *sym = data; - return grecs_hash_string(sym->name, hashsize); + struct grecs_syment *sym = data; + return grecs_hash_string(sym->name, hashsize); } static int @@ -218,6 +248,11 @@ grecs_symtab_remove(struct grecs_symtab *st, void *elt) unsigned int pos, i, j, r; struct grecs_syment *entry; + if (st->itr_level) { + if (grecs_list_remove(st->defer_list[defer_add], elt) == 0) + return 0; + } + pos = st->hash_fun(elt, hash_size[st->hash_num]); for (i = pos; (entry = st->tab[i]);) { if (st->cmp_fun(entry, elt) == 0) @@ -231,7 +266,14 @@ grecs_symtab_remove(struct grecs_symtab *st, void *elt) if (!entry) return ENOENT; + if (st->itr_level) { + symtab_defer_op(st, defer_del, entry); + //FIXME: mark the entry as deleted + return 0; + } + syment_free(st, entry); + st->elcount--; for (;;) { st->tab[i] = NULL; @@ -312,10 +354,20 @@ grecs_symtab_lookup_or_install(struct grecs_symtab *st, void *key, errno = ENOMEM; return NULL; } - st->tab[i] = ent; + if (st->itr_level) { + symtab_defer_op(st, defer_add, ent); + } else { + st->tab[i] = ent; + st->elcount++; + } return ent; } else return st->tab[i]; + } else if (rc == ENOENT && st->itr_level) { + void *ptr = grecs_list_locate(st->defer_list[defer_add], key); + if (ptr) + return ptr; + rc = ENOENT; } errno = rc; return NULL; @@ -337,6 +389,7 @@ grecs_symtab_clear(struct grecs_symtab *st) st->tab[i] = NULL; } } + st->elcount = 0; } struct grecs_symtab * @@ -350,6 +403,7 @@ grecs_symtab_create(size_t elsize, if (st) { memset(st, 0, sizeof(*st)); st->elsize = elsize; + st->elcount = 0; st->hash_fun = hash_fun ? hash_fun : def_hash; st->cmp_fun = cmp_fun ? cmp_fun : def_cmp; st->copy_fun = copy_fun ? copy_fun : def_copy; @@ -381,39 +435,54 @@ grecs_symtab_free(struct grecs_symtab *st) { if (st) { grecs_symtab_clear(st); + grecs_list_free(st->defer_list[defer_add]); + grecs_list_free(st->defer_list[defer_del]); free(st->tab); free(st); } } size_t -grecs_symtab_count_entries(struct grecs_symtab *st) +grecs_symtab_count(struct grecs_symtab *st) { - unsigned i; - size_t count = 0; - - for (i = 0; i < hash_size[st->hash_num]; i++) - if (st->tab[i]) - count++; - return count; + return st->elcount; } int -grecs_symtab_enumerate(struct grecs_symtab *st, grecs_symtab_enumerator_t fun, - void *data) +grecs_symtab_foreach(struct grecs_symtab *st, grecs_symtab_enumerator_t fun, + void *data) { unsigned i; - + struct grecs_syment *ep; + if (!st) return 0; + + ++st->itr_level; + for (i = 0; i < hash_size[st->hash_num]; i++) { - struct grecs_syment *ep = st->tab[i]; - if (ep) { + ep = st->tab[i]; + if (ep && !grecs_list_locate(st->defer_list[defer_del], ep)) { int rc = fun(ep, data); if (rc) return rc; } } + + if (--st->itr_level == 0) { + while ((ep = grecs_list_pop(st->defer_list[defer_del])) != NULL) + grecs_symtab_remove(st, ep); + + while ((ep = grecs_list_pop(st->defer_list[defer_add])) != NULL) { + int install = 1; + if (grecs_symtab_get_index(&i, st, ep, + &install) == 0) { + st->tab[i] = ep; + st->elcount++; + } + } + } + return 0; } |