Signed-off-by: Lai Jiangshan <[email protected]>
---
rculfhash.c | 60 ++++++++++++++++++++++++++++++++++++++--------------------
1 files changed, 39 insertions(+), 21 deletions(-)
diff --git a/rculfhash.c b/rculfhash.c
index 0f36899..63a7ee4 100644
--- a/rculfhash.c
+++ b/rculfhash.c
@@ -91,12 +91,32 @@
* the "dummy node" tables.
* - There is one dummy node table per hash index order. The size of
* each dummy node table is half the number of hashes contained in
- * this order.
- * - call_rcu is used to garbage-collect the old order table.
+ * this order(except order=0).
+ * - synchronzie_rcu is used to garbage-collect the old dummy node table.
* - The per-order dummy node tables contain a compact version of the
* hash table nodes. These tables are invariant after they are
* populated into the hash table.
- *
+ *
+ * Dummy node tables:
+ *
+ * hash table hash table the last all dummy node tables
+ * order size dummy node 0 1 2 3 4 5 6(index)
+ * table size
+ * 0 1 1 1
+ * 1 2 1 1 1
+ * 2 4 2 1 1 2
+ * 3 8 4 1 1 2 4
+ * 4 16 8 1 1 2 4 8
+ * 5 32 16 1 1 2 4 8 16
+ * 6 64 32 1 1 2 4 8 16 32
+ *
+ * When growing/shrinking, We only focus on the last dummy node table
+ * which size is (!order ? 1 : (1 << (order -1))).
+ *
+ * Example for growing/shrinking:
+ * grow hash table from order 5 to 6: init the index=6 dummy node table
+ * shrink hash table from order 6 to 5: fini the index=6 dummy node table
+ *
* A bit of ascii art explanation:
*
* Order index is the off-by-one compare to the actual power of 2 because
@@ -1093,14 +1113,13 @@ void init_table_populate(struct cds_lfht *ht, unsigned
long i,
static
void init_table(struct cds_lfht *ht,
- unsigned long first_order, unsigned long len_order)
+ unsigned long first_order, unsigned long end_order)
{
- unsigned long i, end_order;
+ unsigned long i;
dbg_printf("init table: first_order %lu end_order %lu\n",
- first_order, first_order + len_order);
- end_order = first_order + len_order;
- for (i = first_order; i < end_order; i++) {
+ first_order, end_order);
+ for (i = first_order; i <= end_order; i++) {
unsigned long len;
len = !i ? 1 : 1UL << (i - 1);
@@ -1193,16 +1212,15 @@ void remove_table(struct cds_lfht *ht, unsigned long i,
unsigned long len)
static
void fini_table(struct cds_lfht *ht,
- unsigned long first_order, unsigned long len_order)
+ unsigned long first_order, unsigned long end_order)
{
- long i, end_order;
+ long i;
void *free_by_rcu = NULL;
dbg_printf("fini table: first_order %lu end_order %lu\n",
- first_order, first_order + len_order);
- end_order = first_order + len_order;
+ first_order, end_order);
assert(first_order > 0);
- for (i = end_order - 1; i >= first_order; i--) {
+ for (i = end_order; i >= first_order; i--) {
unsigned long len;
len = !i ? 1 : 1UL << (i - 1);
@@ -1285,11 +1303,11 @@ struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct
hash_fct,
ht->percpu_count = alloc_per_cpu_items_count();
/* this mutex should not nest in read-side C.S. */
pthread_mutex_init(&ht->resize_mutex, NULL);
- order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE)) + 1;
+ order = get_count_order_ulong(max(init_size, MIN_TABLE_SIZE));
ht->flags = flags;
ht->cds_lfht_rcu_thread_offline();
pthread_mutex_lock(&ht->resize_mutex);
- ht->t.resize_target = 1UL << (order - 1);
+ ht->t.resize_target = 1UL << order;
init_table(ht, 0, order);
pthread_mutex_unlock(&ht->resize_mutex);
ht->cds_lfht_rcu_thread_online();
@@ -1596,12 +1614,12 @@ void _do_cds_lfht_grow(struct cds_lfht *ht,
{
unsigned long old_order, new_order;
- old_order = get_count_order_ulong(old_size) + 1;
- new_order = get_count_order_ulong(new_size) + 1;
+ old_order = get_count_order_ulong(old_size);
+ new_order = get_count_order_ulong(new_size);
dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
old_size, old_order, new_size, new_order);
assert(new_size > old_size);
- init_table(ht, old_order, new_order - old_order);
+ init_table(ht, old_order + 1, new_order);
}
/* called with resize mutex held */
@@ -1612,14 +1630,14 @@ void _do_cds_lfht_shrink(struct cds_lfht *ht,
unsigned long old_order, new_order;
new_size = max(new_size, MIN_TABLE_SIZE);
- old_order = get_count_order_ulong(old_size) + 1;
- new_order = get_count_order_ulong(new_size) + 1;
+ old_order = get_count_order_ulong(old_size);
+ new_order = get_count_order_ulong(new_size);
dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
old_size, old_order, new_size, new_order);
assert(new_size < old_size);
/* Remove and unlink all dummy nodes to remove. */
- fini_table(ht, new_order, old_order - new_order);
+ fini_table(ht, new_order + 1, old_order);
}
--
1.7.4.4
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