void teardown()
{
ahtable_free(T);
str_map_destroy(M);
size_t i;
for (i = 0; i < n; ++i) {
free(xs[i]);
}
free(xs);
}
/* Split hybrid node - this is similar operation to burst. */
static void hattrie_split_h(node_ptr parent, node_ptr node)
{
/* Find split point. */
unsigned left_m, right_m;
unsigned char j = hattrie_split_mid(node, &left_m, &right_m);
/* now split into two node cooresponding to ranges [0, j] and
* [j + 1, TRIE_MAXCHAR], respectively. */
/* create new left and right nodes
* one node may reuse existing if it keeps hybrid flag
* hybrid -> pure always needs a new table
*/
unsigned char c0 = node.b->c0, c1 = node.b->c1;
node_ptr left, right;
if (j + 1 == c1) { /* right will be pure */
right.b = ahtable_create();
if (j == c0) { /* left will be pure as well */
left.b = ahtable_create();
} else { /* left will be hybrid */
left.b = node.b;
}
} else { /* right will be hybrid */
right.b = node.b;
left.b = ahtable_create();
}
/* setup created nodes */
left.b->c0 = c0;
left.b->c1 = j;
left.b->flag = c0 == j ? NODE_TYPE_PURE_BUCKET : NODE_TYPE_HYBRID_BUCKET; // need to force it
right.b->c0 = j + 1;
right.b->c1 = c1;
right.b->flag = right.b->c0 == right.b->c1 ?
NODE_TYPE_PURE_BUCKET : NODE_TYPE_HYBRID_BUCKET;
/* update the parent's pointer */
unsigned int c;
for (c = c0; c <= j; ++c) parent.t->xs[c] = left;
for (; c <= c1; ++c) parent.t->xs[c] = right;
/* fill new tables */
hattrie_split_fill(node, left, right, j);
if (node.b != left.b && node.b != right.b) {
ahtable_free(node.b);
}
}
static void hattrie_free_node(node_ptr node)
{
if (*node.flag & NODE_TYPE_TRIE) {
size_t i;
for (i = 0; i < NODE_CHILDS; ++i) {
if (i > 0 && node.t->xs[i].t == node.t->xs[i - 1].t) continue;
/* XXX: recursion might not be the best choice here. It is possible
* to build a very deep trie. */
if (node.t->xs[i].t) hattrie_free_node(node.t->xs[i]);
}
free(node.t);
}
else {
ahtable_free(node.b);
}
}
/* Perform one split operation on the given node with the given parent.
*/
static void hattrie_split(hattrie_t* T, node_ptr parent, node_ptr node)
{
/* only buckets may be split */
assert(*node.flag & NODE_TYPE_PURE_BUCKET ||
*node.flag & NODE_TYPE_HYBRID_BUCKET);
assert(*parent.flag & NODE_TYPE_TRIE);
if (*node.flag & NODE_TYPE_PURE_BUCKET) {
/* turn the pure bucket into a hybrid bucket */
parent.t->xs[node.b->c0].t = alloc_trie_node(T, node);
/* if the bucket had an empty key, move it to the new trie node */
value_t* val = ahtable_tryget(node.b, NULL, 0);
if (val) {
parent.t->xs[node.b->c0].t->val = *val;
parent.t->xs[node.b->c0].t->flag |= NODE_HAS_VAL;
*val = 0;
ahtable_del(node.b, NULL, 0);
}
node.b->c0 = 0x00;
node.b->c1 = NODE_MAXCHAR;
node.b->flag = NODE_TYPE_HYBRID_BUCKET;
return;
}
/* This is a hybrid bucket. Perform a proper split. */
/* count the number of occourances of every leading character */
unsigned int cs[NODE_CHILDS]; // occurance count for leading chars
memset(cs, 0, NODE_CHILDS * sizeof(unsigned int));
size_t len;
const char* key;
ahtable_iter_t* i = ahtable_iter_begin(node.b, false);
while (!ahtable_iter_finished(i)) {
key = ahtable_iter_key(i, &len);
assert(len > 0);
cs[(unsigned char) key[0]] += 1;
ahtable_iter_next(i);
}
ahtable_iter_free(i);
/* choose a split point */
unsigned int left_m, right_m, all_m;
unsigned char j = node.b->c0;
all_m = ahtable_size(node.b);
left_m = cs[j];
right_m = all_m - left_m;
int d;
while (j + 1 < node.b->c1) {
d = abs((int) (left_m + cs[j + 1]) - (int) (right_m - cs[j + 1]));
if (d <= abs(left_m - right_m) && left_m + cs[j + 1] < all_m) {
j += 1;
left_m += cs[j];
right_m -= cs[j];
}
else break;
}
/* now split into two node cooresponding to ranges [0, j] and
* [j + 1, NODE_MAXCHAR], respectively. */
/* create new left and right nodes */
/* TODO: Add a special case if either node is a hybrid bucket containing all
* the keys. In such a case, do not build a new table, just use the old one.
* */
size_t num_slots;
for (num_slots = ahtable_initial_size;
(double) left_m > ahtable_max_load_factor * (double) num_slots;
num_slots *= 2);
node_ptr left, right;
left.b = ahtable_create_n(num_slots);
left.b->c0 = node.b->c0;
left.b->c1 = j;
left.b->flag = left.b->c0 == left.b->c1 ?
NODE_TYPE_PURE_BUCKET : NODE_TYPE_HYBRID_BUCKET;
for (num_slots = ahtable_initial_size;
(double) right_m > ahtable_max_load_factor * (double) num_slots;
num_slots *= 2);
right.b = ahtable_create_n(num_slots);
right.b->c0 = j + 1;
right.b->c1 = node.b->c1;
right.b->flag = right.b->c0 == right.b->c1 ?
NODE_TYPE_PURE_BUCKET : NODE_TYPE_HYBRID_BUCKET;
/* update the parent's pointer */
unsigned int c;
for (c = node.b->c0; c <= j; ++c) parent.t->xs[c] = left;
for (; c <= node.b->c1; ++c) parent.t->xs[c] = right;
/* distribute keys to the new left or right node */
value_t* u;
value_t* v;
i = ahtable_iter_begin(node.b, false);
while (!ahtable_iter_finished(i)) {
key = ahtable_iter_key(i, &len);
u = ahtable_iter_val(i);
assert(len > 0);
/* left */
if ((unsigned char) key[0] <= j) {
if (*left.flag & NODE_TYPE_PURE_BUCKET) {
v = ahtable_get(left.b, key + 1, len - 1);
}
else {
v = ahtable_get(left.b, key, len);
}
*v = *u;
}
/* right */
else {
if (*right.flag & NODE_TYPE_PURE_BUCKET) {
v = ahtable_get(right.b, key + 1, len - 1);
}
else {
v = ahtable_get(right.b, key, len);
}
*v = *u;
}
ahtable_iter_next(i);
}
ahtable_iter_free(i);
ahtable_free(node.b);
}
