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Hash: iterable now per partes by an iterator

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It's now possible to pause iteration through hash. This requires
struct hash_iterator to be allocated somewhere handy.

The iteration itself is surrounded by HASH_WALK_ITER and
HASH_WALK_ITER_END. Call HASH_WALK_ITER_PUT to ask for pausing; it may
still do some more iterations until it comes to a suitable pausing
point. The iterator must be initalized to an empty structure. No cleanup
is needed if iteration is abandoned inbetween.
This commit is contained in:
Maria Matejka 2022-06-29 13:22:40 +02:00
parent b06911f6ef
commit d5e3272f3d
2 changed files with 71 additions and 10 deletions
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24
lib/hash.h
View File

@ -10,7 +10,7 @@
#ifndef _BIRD_HASH_H_
#define _BIRD_HASH_H_
#define HASH(type) struct { type **data; uint count, order; }
#define HASH(type) struct { type **data; uint count; u16 iterators; u8 order; u8 down_requested:1; }
#define HASH_TYPE(v) typeof(** (v).data)
#define HASH_SIZE(v) (1U << (v).order)
@ -125,19 +125,25 @@
#define HASH_MAY_STEP_DOWN_(v,pool,rehash_fn,args) \
({ \
if (((v).count < (HASH_SIZE(v) REHASH_LO_MARK(args))) && \
if ((v).iterators) \
(v).down_requested = 1; \
else if (((v).count < (HASH_SIZE(v) REHASH_LO_MARK(args))) && \
((v).order > (REHASH_LO_BOUND(args)))) \
rehash_fn(&(v), pool, -(REHASH_LO_STEP(args))); \
})
#define HASH_MAY_RESIZE_DOWN_(v,pool,rehash_fn,args) \
({ \
if ((v).iterators) \
(v).down_requested = 1; \
else { \
uint _o = (v).order; \
while (((v).count < ((1U << _o) REHASH_LO_MARK(args))) && \
(_o > (REHASH_LO_BOUND(args)))) \
_o -= (REHASH_LO_STEP(args)); \
if (_o < (v).order) \
rehash_fn(&(v), pool, _o - (v).order); \
} \
})
@ -195,6 +201,20 @@
#define HASH_WALK_FILTER_END } while (0)
#define HASH_WALK_ITER(v, id, n, iter) \
do { \
uint _hash_walk_iter_put = 0; \
uint _shift = 32 - (v).order; \
for ( ; !_hash_walk_iter_put; (iter) += (1U << _shift)) { \
_hash_walk_iter_put = ((iter) + (1U << _shift) == 0); \
for (HASH_TYPE(v) *n = (v).data[(iter) >> _shift]; n; n = id##_NEXT((n)))\
if (HASH_FN(v, id, id##_KEY(n)) >= ((iter) >> _shift)) \
#define HASH_WALK_ITER_PUT (_hash_walk_iter_put = 1)
#define HASH_WALK_ITER_END } } while (0)
static inline void
mem_hash_init(u64 *h)
{

41
lib/hash_test.c
View File

@ -285,6 +285,46 @@ t_walk_filter(void)
return 1;
}
static int
t_walk_iter(void)
{
init_hash();
fill_hash();
u32 hit = 0;
u32 prev_hash = ~0;
for (uint cnt = 0; cnt < MAX_NUM; )
{
u32 last_hash = ~0;
// printf("PUT!\n");
HASH_WALK_ITER(hash, TEST, n, hit)
{
cnt++;
u32 cur_hash = HASH_FN(hash, TEST, n->key);
/*
printf("C%08x L%08x P%08x K%08x H%08x N%p S%d I%ld\n",
cur_hash, last_hash, prev_hash, n->key, hit, n, _shift, n - &nodes[0]);
*/
if (last_hash == ~0U)
{
if (prev_hash != ~0U)
bt_assert(prev_hash < cur_hash);
last_hash = prev_hash = cur_hash;
}
else
bt_assert(last_hash == cur_hash);
if (cnt < MAX_NUM)
HASH_WALK_ITER_PUT;
}
HASH_WALK_ITER_END;
}
return 1;
}
int
main(int argc, char *argv[])
{
@ -299,6 +339,7 @@ main(int argc, char *argv[])
bt_test_suite(t_walk_delsafe_remove, "HASH_WALK_DELSAFE and HASH_REMOVE");
bt_test_suite(t_walk_delsafe_remove2, "HASH_WALK_DELSAFE and HASH_REMOVE2. HASH_REMOVE2 is HASH_REMOVE and smart auto-resize function");
bt_test_suite(t_walk_filter, "HASH_WALK_FILTER");
bt_test_suite(t_walk_iter, "HASH_WALK_ITER");
return bt_exit_value();
}