gpointer
mono_conc_hashtable_lookup (MonoConcurrentHashTable *hash_table, gpointer key)
{
MonoThreadHazardPointers* hp;
conc_table *table;
int hash, i, table_mask;
key_value_pair *kvs;
hash = mix_hash (hash_table->hash_func (key));
hp = mono_hazard_pointer_get ();
retry:
table = (conc_table *)mono_get_hazardous_pointer ((gpointer volatile*)&hash_table->table, hp, 0);
table_mask = table->table_size - 1;
kvs = table->kvs;
i = hash & table_mask;
if (G_LIKELY (!hash_table->equal_func)) {
while (kvs [i].key) {
if (key == kvs [i].key) {
gpointer value;
/* The read of keys must happen before the read of values */
mono_memory_barrier ();
value = kvs [i].value;
/* FIXME check for NULL if we add suppport for removal */
mono_hazard_pointer_clear (hp, 0);
return value;
}
i = (i + 1) & table_mask;
}
} else {
GEqualFunc equal = hash_table->equal_func;
while (kvs [i].key) {
if (kvs [i].key != TOMBSTONE && equal (key, kvs [i].key)) {
gpointer value;
/* The read of keys must happen before the read of values */
mono_memory_barrier ();
value = kvs [i].value;
/* We just read a value been deleted, try again. */
if (G_UNLIKELY (!value))
goto retry;
mono_hazard_pointer_clear (hp, 0);
return value;
}
i = (i + 1) & table_mask;
}
}
/* The table might have expanded and the value is now on the newer table */
mono_memory_barrier ();
if (hash_table->table != table)
goto retry;
mono_hazard_pointer_clear (hp, 0);
return NULL;
}
static Descriptor*
desc_alloc (MonoMemAccountType type)
{
MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
Descriptor *desc;
for (;;) {
gboolean success;
desc = (Descriptor *) mono_get_hazardous_pointer ((volatile gpointer *)&desc_avail, hp, 1);
if (desc) {
Descriptor *next = desc->next;
success = (mono_atomic_cas_ptr ((volatile gpointer *)&desc_avail, next, desc) == desc);
} else {
size_t desc_size = sizeof (Descriptor);
Descriptor *d;
int i;
desc = (Descriptor *) mono_valloc (NULL, desc_size * NUM_DESC_BATCH, prot_flags_for_activate (TRUE), type);
g_assertf (desc, "Failed to allocate memory for the lock free allocator");
/* Organize into linked list. */
d = desc;
for (i = 0; i < NUM_DESC_BATCH; ++i) {
Descriptor *next = (i == (NUM_DESC_BATCH - 1)) ? NULL : (Descriptor*)((char*)desc + ((i + 1) * desc_size));
d->next = next;
mono_lock_free_queue_node_init (&d->node, TRUE);
d = next;
}
mono_memory_write_barrier ();
success = (mono_atomic_cas_ptr ((volatile gpointer *)&desc_avail, desc->next, NULL) == NULL);
if (!success)
mono_vfree (desc, desc_size * NUM_DESC_BATCH, type);
}
mono_hazard_pointer_clear (hp, 1);
if (success)
break;
}
g_assert (!desc->in_use);
desc->in_use = TRUE;
return desc;
}
