+/*
+ * TODO: keys are currently assumed <= sizeof(void *). Key target never freed.
+ */
+
#define _LGPL_SOURCE
#include <stdlib.h>
#include <urcu.h>
#include <urcu-defer.h>
#include <errno.h>
#include <urcu-ht.h>
+#include <urcu/jhash.h>
+#include <stdio.h>
struct rcu_ht_node;
};
struct rcu_ht {
- struct rcu_ht_node *tbl[HASH_SIZE];
+ struct rcu_ht_node **tbl;
ht_hash_fct hash_fct;
void (*free_fct)(void *data); /* fct to free data */
+ uint32_t keylen;
+ uint32_t hashseed;
+ struct ht_size {
+ unsigned long add;
+ unsigned long lookup;
+ } size;
};
-struct rcu_ht *ht_new(ht_hash_fct hash_fct, void (*free_fct)(void *data))
+struct rcu_ht *ht_new(ht_hash_fct hash_fct, void (*free_fct)(void *data),
+ unsigned long init_size, uint32_t keylen,
+ uint32_t hashseed)
{
struct rcu_ht *ht;
ht = calloc(1, sizeof(struct rcu_ht));
ht->hash_fct = hash_fct;
ht->free_fct = free_fct;
+ ht->size.add = init_size;
+ ht->size.lookup = init_size;
+ ht->keylen = keylen;
+ ht->hashseed = hashseed;
+ ht->tbl = calloc(init_size, sizeof(struct rcu_ht_node *));
return ht;
}
-/* delete all elements */
-void ht_delete_all(struct rcu_ht *ht)
-{
- unsigned long i;
- struct rcu_ht_node **prev, *node;
-
- for (i = 0; i < HASH_SIZE; i++) {
- rcu_read_lock();
-
- prev = &ht->tbl[i];
- node = rcu_dereference(*prev);
- /*
- * Cut the head, therefore whole bucket will be unused
- * after GP. (except for concurrent additions)
- */
- rcu_assign_pointer(prev, NULL);
- for (;;) {
- if (likely(!node)) {
- break;
- }
- prev = &node->next;
- if (node->data)
- call_rcu(ht->free_fct, node->data);
- call_rcu(free, node);
- node = rcu_dereference(*prev);
- }
- rcu_read_unlock();
- }
-}
-
-/*
- * Should only be called when no more concurrent readers nor writers can
- * possibly access the table.
- */
-void ht_destroy(struct rcu_ht *ht)
-{
- ht_delete_all(ht);
- free(ht);
-}
-
void *ht_lookup(struct rcu_ht *ht, void *key)
{
unsigned long hash;
struct rcu_ht_node *node;
void *ret;
- hash = ht->hash_fct(key);
+ hash = ht->hash_fct(key, ht->keylen, ht->hashseed) % ht->size.lookup;
rcu_read_lock();
node = rcu_dereference(ht->tbl[hash]);
new_head = calloc(1, sizeof(struct rcu_ht_node));
new_head->key = key;
new_head->data = data;
- hash = ht->hash_fct(key);
-
/* here comes the fun and tricky part.
* Add at the beginning with a cmpxchg.
* Hold a read lock between the moment the first element is read
retry:
rcu_read_lock();
+ hash = ht->hash_fct(key, ht->keylen, ht->hashseed) % ht->size.add;
+
old_head = node = rcu_dereference(ht->tbl[hash]);
for (;;) {
if (likely(!node)) {
}
node = rcu_dereference(node->next);
}
+ new_head->next = old_head;
if (rcu_cmpxchg_pointer(&ht->tbl[hash], old_head, new_head) != old_head)
goto restart;
end:
unsigned long hash;
void *data;
- hash = ht->hash_fct(key);
-
retry:
rcu_read_lock();
+ hash = ht->hash_fct(key, ht->keylen, ht->hashseed) % ht->size.lookup;
+
prev = &ht->tbl[hash];
node = rcu_dereference(*prev);
for (;;) {
if (likely(!node)) {
data = (void *)(unsigned long)-ENOENT;
- goto end;
+ goto error;
}
if (node->key == key) {
break;
/* Found it ! pointer to object is in "prev" */
if (rcu_cmpxchg_pointer(prev, node, node->next) != node)
goto restart;
-end:
+
+ /* From that point, we own node. We can free it outside of read lock */
rcu_read_unlock();
data = node->data;
call_rcu(free, node);
+ return data;
+error:
+ rcu_read_unlock();
return data;
/* restart loop, release and re-take the read lock to be kind to GP */
void *data;
data = ht_steal(ht, key);
- if (data) {
- if (ht->free_fct && data)
+ if (data && data != (void *)(unsigned long)-ENOENT) {
+ if (ht->free_fct)
call_rcu(ht->free_fct, data);
return 0;
} else {
}
}
-unsigned long stupid_hash(void *key)
+/* Delete all old elements. Allow concurrent writer accesses. */
+int ht_delete_all(struct rcu_ht *ht)
{
- return (unsigned long)key % HASH_SIZE;
+ unsigned long i;
+ struct rcu_ht_node **prev, *node, *inext;
+ int cnt = 0;
+
+ for (i = 0; i < ht->size.lookup; i++) {
+ rcu_read_lock();
+ prev = &ht->tbl[i];
+ /*
+ * Cut the head. After that, we own the first element.
+ */
+ node = rcu_xchg_pointer(prev, NULL);
+ if (!node) {
+ rcu_read_unlock();
+ continue;
+ }
+ /*
+ * We manage a list shared with concurrent writers and readers.
+ * Note that a concurrent add may or may not be deleted by us,
+ * depending if it arrives before or after the head is cut.
+ * "node" points to our first node. Remove first elements
+ * iteratively.
+ */
+ for (;;) {
+ inext = NULL;
+ prev = &node->next;
+ if (prev)
+ inext = rcu_xchg_pointer(prev, NULL);
+ /*
+ * "node" is the first element of the list we have cut.
+ * We therefore own it, no concurrent writer may delete
+ * it. There can only be concurrent lookups. Concurrent
+ * add can only be done on a bucket head, but we've cut
+ * it already. inext is also owned by us, because we
+ * have exchanged it for "NULL". It will therefore be
+ * safe to use it after a G.P.
+ */
+ rcu_read_unlock();
+ if (node->data)
+ call_rcu(ht->free_fct, node->data);
+ call_rcu(free, node);
+ cnt++;
+ if (likely(!inext))
+ break;
+ rcu_read_lock();
+ node = inext;
+ }
+ }
+ return cnt;
+}
+
+/*
+ * Should only be called when no more concurrent readers nor writers can
+ * possibly access the table.
+ */
+int ht_destroy(struct rcu_ht *ht)
+{
+ int ret;
+
+ ret = ht_delete_all(ht);
+ free(ht->tbl);
+ free(ht);
+ return ret;
+}
+
+/*
+ * Expects keys <= than pointer size to be encoded in the pointer itself.
+ */
+uint32_t ht_jhash(void *key, uint32_t length, uint32_t initval)
+{
+ uint32_t ret;
+ void *vkey;
+
+ if (length <= sizeof(u32))
+ vkey = &key;
+ else
+ vkey = key;
+ ret = jhash(vkey, length, initval);
+ return ret;
}
projects / urcu.git / blobdiff