#define dbg_printf(fmt, args...)
#endif
-/* For testing */
-#define POISON_FREE
-
/*
* Per-CPU split-counters lazily update the global counter each 1024
* addition/removal. It automatically keeps track of resize required.
#define CHAIN_LEN_RESIZE_THRESHOLD 3
/*
- * Define the minimum table size. Protects against hash table resize overload
- * when too many entries are added quickly before the resize can complete.
- * This is especially the case if the table could be shrinked to a size of 1.
- * TODO: we might want to make the add/remove operations help the resize to
- * add or remove dummy nodes when a resize is ongoing to ensure upper-bound on
- * chain length.
+ * Define the minimum table size.
*/
#define MIN_TABLE_SIZE 128
+#if (CAA_BITS_PER_LONG == 32)
+#define MAX_TABLE_ORDER 32
+#else
+#define MAX_TABLE_ORDER 64
+#endif
+
+#ifndef min
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
#ifndef max
#define max(a, b) ((a) > (b) ? (a) : (b))
#endif
};
struct rcu_table {
- unsigned long size; /* always a power of 2 */
+ unsigned long size; /* always a power of 2, shared (RCU) */
unsigned long resize_target;
int resize_initiated;
- struct rcu_head head;
- struct rcu_level *tbl[0];
+ struct rcu_level *tbl[MAX_TABLE_ORDER];
};
struct cds_lfht {
- struct rcu_table *t; /* shared */
+ struct rcu_table t;
cds_lfht_hash_fct hash_fct;
cds_lfht_compare_fct compare_fct;
unsigned long hash_seed;
int flags;
+ /*
+ * We need to put the work threads offline (QSBR) when taking this
+ * mutex, because we use synchronize_rcu within this mutex critical
+ * section, which waits on read-side critical sections, and could
+ * therefore cause grace-period deadlock if we hold off RCU G.P.
+ * completion.
+ */
pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */
unsigned int in_progress_resize, in_progress_destroy;
void (*cds_lfht_call_rcu)(struct rcu_head *head,
void (*cds_lfht_synchronize_rcu)(void);
void (*cds_lfht_rcu_read_lock)(void);
void (*cds_lfht_rcu_read_unlock)(void);
+ void (*cds_lfht_rcu_thread_offline)(void);
+ void (*cds_lfht_rcu_thread_online)(void);
unsigned long count; /* global approximate item count */
struct ht_items_count *percpu_count; /* per-cpu item count */
};
struct cds_lfht *ht;
};
+static
+struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
+ unsigned long size,
+ struct cds_lfht_node *node,
+ int unique, int dummy);
+
/*
* Algorithm to reverse bits in a word by lookup table, extended to
* 64-bit words.
#endif
static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth);
+void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth);
/*
* If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
unsigned long count);
static long nr_cpus_mask = -1;
}
static
-void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_add(struct cds_lfht *ht, unsigned long size)
{
unsigned long percpu_count;
int cpu;
1UL << COUNT_COMMIT_ORDER);
/* If power of 2 */
if (!(count & (count - 1))) {
- if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
- < t->size)
+ if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
return;
dbg_printf("add set global %lu\n", count);
- cds_lfht_resize_lazy_count(ht, t,
+ cds_lfht_resize_lazy_count(ht, size,
count >> (CHAIN_LEN_TARGET - 1));
}
}
}
static
-void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_remove(struct cds_lfht *ht, unsigned long size)
{
unsigned long percpu_count;
int cpu;
-(1UL << COUNT_COMMIT_ORDER));
/* If power of 2 */
if (!(count & (count - 1))) {
- if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
- >= t->size)
+ if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
return;
dbg_printf("remove set global %lu\n", count);
- cds_lfht_resize_lazy_count(ht, t,
+ cds_lfht_resize_lazy_count(ht, size,
count >> (CHAIN_LEN_TARGET - 1));
}
}
}
static
-void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_add(struct cds_lfht *ht, unsigned long size)
{
}
static
-void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
+void ht_count_remove(struct cds_lfht *ht, unsigned long size)
{
}
static
-void check_resize(struct cds_lfht *ht, struct rcu_table *t,
- uint32_t chain_len)
+void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
{
unsigned long count;
dbg_printf("WARNING: large chain length: %u.\n",
chain_len);
if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
- cds_lfht_resize_lazy(ht, t,
+ cds_lfht_resize_lazy(ht, size,
get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
}
return v;
}
-static
-void cds_lfht_free_table_cb(struct rcu_head *head)
-{
- struct rcu_table *t =
- caa_container_of(head, struct rcu_table, head);
- poison_free(t);
-}
-
static
void cds_lfht_free_level(struct rcu_head *head)
{
* Remove all logically deleted nodes from a bucket up to a certain node key.
*/
static
-void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node)
+int _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node)
{
struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
- struct cds_lfht_node *iter_trace[64];
- unsigned long trace_idx = 0;
- memset(iter_trace, 0, sizeof(iter_trace));
assert(!is_dummy(dummy));
assert(!is_removed(dummy));
assert(!is_dummy(node));
assert(!is_removed(node));
for (;;) {
- iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x1;
iter_prev = dummy;
/* We can always skip the dummy node initially */
iter = rcu_dereference(iter_prev->p.next);
- iter_trace[trace_idx++ & (64 - 1)] = iter;
+ if (unlikely(iter == NULL)) {
+ /*
+ * We are executing concurrently with a hash table
+ * expand, so we see a dummy node with NULL next value.
+ * Help expand by linking this node into the list and
+ * retry.
+ */
+ return 1;
+ }
assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
/*
* We should never be called with dummy (start of chain)
assert(dummy != node);
for (;;) {
if (unlikely(!clear_flag(iter)))
- return;
+ return 0;
if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
- return;
+ return 0;
next = rcu_dereference(clear_flag(iter)->p.next);
if (likely(is_removed(next)))
break;
iter_prev = clear_flag(iter);
iter = next;
- iter_trace[trace_idx++ & (64 - 1)] = iter;
}
assert(!is_removed(iter));
if (is_dummy(iter))
else
new_next = clear_flag(next);
(void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
- iter_trace[trace_idx++ & (64 - 1)] = (void *) 0x2;
}
+ return 0;
}
static
-struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht, struct rcu_table *t,
- struct cds_lfht_node *node, int unique, int dummy)
+struct cds_lfht_node *_cds_lfht_add(struct cds_lfht *ht,
+ unsigned long size,
+ struct cds_lfht_node *node,
+ int unique, int dummy)
{
struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
*dummy_node;
assert(!is_dummy(node));
assert(!is_removed(node));
- if (!t->size) {
+ if (!size) {
assert(dummy);
node->p.next = flag_dummy(NULL);
return node; /* Initial first add (head) */
* iter_prev points to the non-removed node prior to the
* insert location.
*/
- index = hash & (t->size - 1);
+ index = hash & (size - 1);
order = get_count_order_ulong(index + 1);
- lookup = &t->tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)];
+ lookup = &ht->t.tbl[order]->nodes[index & ((!order ? 0 : (1UL << (order - 1))) - 1)];
iter_prev = (struct cds_lfht_node *) lookup;
/* We can always skip the dummy node initially */
iter = rcu_dereference(iter_prev->p.next);
+ if (unlikely(iter == NULL)) {
+ /*
+ * We are executing concurrently with a hash table
+ * expand, so we see a dummy node with NULL next value.
+ * Help expand by linking this node into the list and
+ * retry.
+ */
+ (void) _cds_lfht_add(ht, size >> 1, iter_prev, 0, 1);
+ continue; /* retry */
+ }
assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
for (;;) {
- /* TODO: check if removed */
+ /*
+ * When adding a dummy node, we allow concurrent
+ * add/removal to help. If we find the dummy node in
+ * place, skip its insertion.
+ */
+ if (unlikely(dummy && clear_flag(iter) == node))
+ return node;
if (unlikely(!clear_flag(iter)))
goto insert;
- /* TODO: check if removed */
if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
goto insert;
next = rcu_dereference(clear_flag(iter)->p.next);
/* Only account for identical reverse hash once */
if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash
&& !is_dummy(next))
- check_resize(ht, t, ++chain_len);
+ check_resize(ht, size, ++chain_len);
iter_prev = clear_flag(iter);
iter = next;
}
}
gc_end:
/* Garbage collect logically removed nodes in the bucket */
- index = hash & (t->size - 1);
+ index = hash & (size - 1);
order = get_count_order_ulong(index + 1);
- lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+ lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
dummy_node = (struct cds_lfht_node *) lookup;
- _cds_lfht_gc_bucket(dummy_node, node);
+ if (_cds_lfht_gc_bucket(dummy_node, node)) {
+ /* Help expand */
+ (void) _cds_lfht_add(ht, size >> 1, dummy_node, 0, 1);
+ goto gc_end; /* retry */
+ }
return node;
}
static
-int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t,
- struct cds_lfht_node *node, int dummy_removal)
+int _cds_lfht_remove(struct cds_lfht *ht, unsigned long size,
+ struct cds_lfht_node *node,
+ int dummy_removal)
{
struct cds_lfht_node *dummy, *next, *old;
struct _cds_lfht_node *lookup;
* the node, and remove it (along with any other logically removed node)
* if found.
*/
+gc_retry:
hash = bit_reverse_ulong(node->p.reverse_hash);
- assert(t->size > 0);
- index = hash & (t->size - 1);
+ assert(size > 0);
+ index = hash & (size - 1);
order = get_count_order_ulong(index + 1);
- lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
+ lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1)) - 1))];
dummy = (struct cds_lfht_node *) lookup;
- _cds_lfht_gc_bucket(dummy, node);
+ if (_cds_lfht_gc_bucket(dummy, node)) {
+ /* Help expand */
+ (void) _cds_lfht_add(ht, size >> 1, dummy, 0, 1);
+ goto gc_retry; /* retry */
+ }
end:
/*
* Only the flagging action indicated that we (and no other)
return -ENOENT;
}
+static
+void init_table_hash(struct cds_lfht *ht, unsigned long i,
+ unsigned long len)
+{
+ unsigned long j;
+
+ for (j = 0; j < len; j++) {
+ struct cds_lfht_node *new_node =
+ (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
+
+ dbg_printf("init hash entry: i %lu j %lu hash %lu\n",
+ i, j, !i ? 0 : (1UL << (i - 1)) + j);
+ new_node->p.reverse_hash =
+ bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
+ if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+ break;
+ }
+}
+
/*
* Holding RCU read lock to protect _cds_lfht_add against memory
* reclaim that could be performed by other call_rcu worker threads (ABA
* problem).
*/
static
-void init_table(struct cds_lfht *ht, struct rcu_table *t,
+void init_table_link(struct cds_lfht *ht, unsigned long i, unsigned long len)
+{
+ unsigned long j;
+
+ ht->cds_lfht_rcu_thread_online();
+ ht->cds_lfht_rcu_read_lock();
+ for (j = 0; j < len; j++) {
+ struct cds_lfht_node *new_node =
+ (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
+
+ dbg_printf("init link: i %lu j %lu hash %lu\n",
+ i, j, !i ? 0 : (1UL << (i - 1)) + j);
+ (void) _cds_lfht_add(ht, !i ? 0 : (1UL << (i - 1)),
+ new_node, 0, 1);
+ if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+ break;
+ }
+ ht->cds_lfht_rcu_read_unlock();
+ ht->cds_lfht_rcu_thread_offline();
+}
+
+static
+void init_table(struct cds_lfht *ht,
unsigned long first_order, unsigned long len_order)
{
unsigned long i, end_order;
dbg_printf("init table: first_order %lu end_order %lu\n",
first_order, first_order + len_order);
end_order = first_order + len_order;
- t->size = !first_order ? 0 : (1UL << (first_order - 1));
for (i = first_order; i < end_order; i++) {
- unsigned long j, len;
+ unsigned long len;
len = !i ? 1 : 1UL << (i - 1);
dbg_printf("init order %lu len: %lu\n", i, len);
- t->tbl[i] = calloc(1, sizeof(struct rcu_level)
+
+ /* Stop expand if the resize target changes under us */
+ if (CMM_LOAD_SHARED(ht->t.resize_target) < (!i ? 1 : (1UL << i)))
+ break;
+
+ ht->t.tbl[i] = calloc(1, sizeof(struct rcu_level)
+ (len * sizeof(struct _cds_lfht_node)));
- ht->cds_lfht_rcu_read_lock();
- for (j = 0; j < len; j++) {
- struct cds_lfht_node *new_node =
- (struct cds_lfht_node *) &t->tbl[i]->nodes[j];
-
- dbg_printf("init entry: i %lu j %lu hash %lu\n",
- i, j, !i ? 0 : (1UL << (i - 1)) + j);
- new_node->p.reverse_hash =
- bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
- (void) _cds_lfht_add(ht, t, new_node, 0, 1);
- if (CMM_LOAD_SHARED(ht->in_progress_destroy))
- break;
- }
- ht->cds_lfht_rcu_read_unlock();
- /* Update table size */
- t->size = !i ? 1 : (1UL << i);
- dbg_printf("init new size: %lu\n", t->size);
+
+ /* Set all dummy nodes reverse hash values for a level */
+ init_table_hash(ht, i, len);
+
+ /*
+ * Update table size. At this point, concurrent add/remove see
+ * dummy nodes with correctly initialized reverse hash value,
+ * but with NULL next pointers. If they do, they can help us
+ * link the dummy nodes into the list and retry.
+ */
+ cmm_smp_wmb(); /* populate data before RCU size */
+ CMM_STORE_SHARED(ht->t.size, !i ? 1 : (1UL << i));
+
+ /*
+ * Link all dummy nodes into the table. Concurrent
+ * add/remove are helping us.
+ */
+ init_table_link(ht, i, len);
+
+ dbg_printf("init new size: %lu\n", !i ? 1 : (1UL << i));
if (CMM_LOAD_SHARED(ht->in_progress_destroy))
break;
}
- t->resize_target = t->size;
- t->resize_initiated = 0;
}
/*
* Holding RCU read lock to protect _cds_lfht_remove against memory
* reclaim that could be performed by other call_rcu worker threads (ABA
* problem).
+ * For a single level, we logically remove and garbage collect each node.
+ *
+ * As a design choice, we perform logical removal and garbage collection on a
+ * node-per-node basis to simplify this algorithm. We also assume keeping good
+ * cache locality of the operation would overweight possible performance gain
+ * that could be achieved by batching garbage collection for multiple levels.
+ * However, this would have to be justified by benchmarks.
+ *
+ * Concurrent removal and add operations are helping us perform garbage
+ * collection of logically removed nodes. We guarantee that all logically
+ * removed nodes have been garbage-collected (unlinked) before call_rcu is
+ * invoked to free a hole level of dummy nodes (after a grace period).
+ *
+ * Logical removal and garbage collection can therefore be done in batch or on a
+ * node-per-node basis, as long as the guarantee above holds.
*/
static
-void fini_table(struct cds_lfht *ht, struct rcu_table *t,
+void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len)
+{
+ unsigned long j;
+
+ ht->cds_lfht_rcu_thread_online();
+ ht->cds_lfht_rcu_read_lock();
+ for (j = 0; j < len; j++) {
+ struct cds_lfht_node *fini_node =
+ (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
+
+ dbg_printf("remove entry: i %lu j %lu hash %lu\n",
+ i, j, !i ? 0 : (1UL << (i - 1)) + j);
+ fini_node->p.reverse_hash =
+ bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
+ (void) _cds_lfht_remove(ht, !i ? 0 : (1UL << (i - 1)),
+ fini_node, 1);
+ if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+ break;
+ }
+ ht->cds_lfht_rcu_read_unlock();
+ ht->cds_lfht_rcu_thread_offline();
+}
+
+static
+void fini_table(struct cds_lfht *ht,
unsigned long first_order, unsigned long len_order)
{
long i, end_order;
first_order, first_order + len_order);
end_order = first_order + len_order;
assert(first_order > 0);
- assert(t->size == (1UL << (end_order - 1)));
for (i = end_order - 1; i >= first_order; i--) {
- unsigned long j, len;
+ unsigned long len;
len = !i ? 1 : 1UL << (i - 1);
dbg_printf("fini order %lu len: %lu\n", i, len);
+
+ /* Stop shrink if the resize target changes under us */
+ if (CMM_LOAD_SHARED(ht->t.resize_target) > (1UL << (i - 1)))
+ break;
+
+ cmm_smp_wmb(); /* populate data before RCU size */
+ CMM_STORE_SHARED(ht->t.size, 1UL << (i - 1));
+
/*
- * Update table size. Need to shrink this table prior to
- * removal so gc lookups use non-logically-removed dummy
- * nodes.
+ * We need to wait for all add operations to reach Q.S. (and
+ * thus use the new table for lookups) before we can start
+ * releasing the old dummy nodes. Otherwise their lookup will
+ * return a logically removed node as insert position.
*/
- t->size = 1UL << (i - 1);
- /* Unlink */
- ht->cds_lfht_rcu_read_lock();
- for (j = 0; j < len; j++) {
- struct cds_lfht_node *fini_node =
- (struct cds_lfht_node *) &t->tbl[i]->nodes[j];
-
- dbg_printf("fini entry: i %lu j %lu hash %lu\n",
- i, j, !i ? 0 : (1UL << (i - 1)) + j);
- fini_node->p.reverse_hash =
- bit_reverse_ulong(!i ? 0 : (1UL << (i - 1)) + j);
- (void) _cds_lfht_remove(ht, t, fini_node, 1);
- if (CMM_LOAD_SHARED(ht->in_progress_destroy))
- break;
- }
- ht->cds_lfht_rcu_read_unlock();
- ht->cds_lfht_call_rcu(&t->tbl[i]->head, cds_lfht_free_level);
- dbg_printf("fini new size: %lu\n", t->size);
+ ht->cds_lfht_synchronize_rcu();
+
+ /*
+ * Set "removed" flag in dummy nodes about to be removed.
+ * Unlink all now-logically-removed dummy node pointers.
+ * Concurrent add/remove operation are helping us doing
+ * the gc.
+ */
+ remove_table(ht, i, len);
+
+ ht->cds_lfht_call_rcu(&ht->t.tbl[i]->head, cds_lfht_free_level);
+
+ dbg_printf("fini new size: %lu\n", 1UL << i);
if (CMM_LOAD_SHARED(ht->in_progress_destroy))
break;
}
- t->resize_target = t->size;
- t->resize_initiated = 0;
}
struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
void (*func)(struct rcu_head *head)),
void (*cds_lfht_synchronize_rcu)(void),
void (*cds_lfht_rcu_read_lock)(void),
- void (*cds_lfht_rcu_read_unlock)(void))
+ void (*cds_lfht_rcu_read_unlock)(void),
+ void (*cds_lfht_rcu_thread_offline)(void),
+ void (*cds_lfht_rcu_thread_online)(void))
{
struct cds_lfht *ht;
unsigned long order;
ht->cds_lfht_synchronize_rcu = cds_lfht_synchronize_rcu;
ht->cds_lfht_rcu_read_lock = cds_lfht_rcu_read_lock;
ht->cds_lfht_rcu_read_unlock = cds_lfht_rcu_read_unlock;
- ht->in_progress_resize = 0;
+ ht->cds_lfht_rcu_thread_offline = cds_lfht_rcu_thread_offline;
+ ht->cds_lfht_rcu_thread_online = cds_lfht_rcu_thread_online;
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;
- ht->t = calloc(1, sizeof(struct cds_lfht)
- + (order * sizeof(struct rcu_level *)));
- ht->t->size = 0;
ht->flags = flags;
+ ht->cds_lfht_rcu_thread_offline();
pthread_mutex_lock(&ht->resize_mutex);
- init_table(ht, ht->t, 0, order);
+ ht->t.resize_target = 1UL << (order - 1);
+ init_table(ht, 0, order);
pthread_mutex_unlock(&ht->resize_mutex);
+ ht->cds_lfht_rcu_thread_online();
return ht;
}
struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len)
{
- struct rcu_table *t;
struct cds_lfht_node *node, *next;
struct _cds_lfht_node *lookup;
- unsigned long hash, reverse_hash, index, order;
+ unsigned long hash, reverse_hash, index, order, size;
hash = ht->hash_fct(key, key_len, ht->hash_seed);
reverse_hash = bit_reverse_ulong(hash);
- t = rcu_dereference(ht->t);
- index = hash & (t->size - 1);
+ size = rcu_dereference(ht->t.size);
+ index = hash & (size - 1);
order = get_count_order_ulong(index + 1);
- lookup = &t->tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)];
+ lookup = &ht->t.tbl[order]->nodes[index & (!order ? 0 : ((1UL << (order - 1))) - 1)];
dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
hash, index, order, index & (!order ? 0 : ((1UL << (order - 1)) - 1)));
node = (struct cds_lfht_node *) lookup;
void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node)
{
- struct rcu_table *t;
- unsigned long hash;
+ unsigned long hash, size;
hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
- t = rcu_dereference(ht->t);
- (void) _cds_lfht_add(ht, t, node, 0, 0);
- ht_count_add(ht, t);
+ size = rcu_dereference(ht->t.size);
+ (void) _cds_lfht_add(ht, size, node, 0, 0);
+ ht_count_add(ht, size);
}
struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
struct cds_lfht_node *node)
{
- struct rcu_table *t;
- unsigned long hash;
+ unsigned long hash, size;
struct cds_lfht_node *ret;
hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
- t = rcu_dereference(ht->t);
- ret = _cds_lfht_add(ht, t, node, 1, 0);
+ size = rcu_dereference(ht->t.size);
+ ret = _cds_lfht_add(ht, size, node, 1, 0);
if (ret != node)
- ht_count_add(ht, t);
+ ht_count_add(ht, size);
return ret;
}
int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node)
{
- struct rcu_table *t;
+ unsigned long size;
int ret;
- t = rcu_dereference(ht->t);
- ret = _cds_lfht_remove(ht, t, node, 0);
+ size = rcu_dereference(ht->t.size);
+ ret = _cds_lfht_remove(ht, size, node, 0);
if (!ret)
- ht_count_remove(ht, t);
+ ht_count_remove(ht, size);
return ret;
}
static
int cds_lfht_delete_dummy(struct cds_lfht *ht)
{
- struct rcu_table *t;
struct cds_lfht_node *node;
struct _cds_lfht_node *lookup;
- unsigned long order, i;
+ unsigned long order, i, size;
- t = ht->t;
/* Check that the table is empty */
- lookup = &t->tbl[0]->nodes[0];
+ lookup = &ht->t.tbl[0]->nodes[0];
node = (struct cds_lfht_node *) lookup;
do {
node = clear_flag(node)->p.next;
return -EPERM;
assert(!is_removed(node));
} while (clear_flag(node));
+ /*
+ * size accessed without rcu_dereference because hash table is
+ * being destroyed.
+ */
+ size = ht->t.size;
/* Internal sanity check: all nodes left should be dummy */
- for (order = 0; order < get_count_order_ulong(t->size) + 1; order++) {
+ for (order = 0; order < get_count_order_ulong(size) + 1; order++) {
unsigned long len;
len = !order ? 1 : 1UL << (order - 1);
for (i = 0; i < len; i++) {
dbg_printf("delete order %lu i %lu hash %lu\n",
order, i,
- bit_reverse_ulong(t->tbl[order]->nodes[i].reverse_hash));
- assert(is_dummy(t->tbl[order]->nodes[i].next));
+ bit_reverse_ulong(ht->t.tbl[order]->nodes[i].reverse_hash));
+ assert(is_dummy(ht->t.tbl[order]->nodes[i].next));
}
- poison_free(t->tbl[order]);
+ poison_free(ht->t.tbl[order]);
}
return 0;
}
ret = cds_lfht_delete_dummy(ht);
if (ret)
return ret;
- poison_free(ht->t);
free_per_cpu_items_count(ht->percpu_count);
poison_free(ht);
return ret;
unsigned long *count,
unsigned long *removed)
{
- struct rcu_table *t;
struct cds_lfht_node *node, *next;
struct _cds_lfht_node *lookup;
unsigned long nr_dummy = 0;
*count = 0;
*removed = 0;
- t = rcu_dereference(ht->t);
/* Count non-dummy nodes in the table */
- lookup = &t->tbl[0]->nodes[0];
+ lookup = &ht->t.tbl[0]->nodes[0];
node = (struct cds_lfht_node *) lookup;
do {
next = rcu_dereference(node->p.next);
/* called with resize mutex held */
static
-void _do_cds_lfht_grow(struct cds_lfht *ht, struct rcu_table *old_t,
+void _do_cds_lfht_grow(struct cds_lfht *ht,
unsigned long old_size, unsigned long new_size)
{
unsigned long old_order, new_order;
- struct rcu_table *new_t;
old_order = get_count_order_ulong(old_size) + 1;
new_order = get_count_order_ulong(new_size) + 1;
printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
old_size, old_order, new_size, new_order);
- new_t = malloc(sizeof(struct cds_lfht)
- + (new_order * sizeof(struct rcu_level *)));
assert(new_size > old_size);
- memcpy(&new_t->tbl, &old_t->tbl,
- old_order * sizeof(struct rcu_level *));
- init_table(ht, new_t, old_order, new_order - old_order);
- /* Changing table and size atomically wrt lookups */
- rcu_assign_pointer(ht->t, new_t);
- ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb);
+ init_table(ht, old_order, new_order - old_order);
}
/* called with resize mutex held */
static
-void _do_cds_lfht_shrink(struct cds_lfht *ht, struct rcu_table *old_t,
+void _do_cds_lfht_shrink(struct cds_lfht *ht,
unsigned long old_size, unsigned long new_size)
{
unsigned long old_order, new_order;
- struct rcu_table *new_t;
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;
printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
old_size, old_order, new_size, new_order);
- new_t = malloc(sizeof(struct cds_lfht)
- + (new_order * sizeof(struct rcu_level *)));
assert(new_size < old_size);
- memcpy(&new_t->tbl, &old_t->tbl,
- new_order * sizeof(struct rcu_level *));
- new_t->size = !new_order ? 1 : (1UL << (new_order - 1));
- assert(new_t->size == new_size);
- new_t->resize_target = new_t->size;
- new_t->resize_initiated = 0;
-
- /* Changing table and size atomically wrt lookups */
- rcu_assign_pointer(ht->t, new_t);
-
- /*
- * We need to wait for all add operations to reach Q.S. (and
- * thus use the new table for lookups) before we can start
- * releasing the old dummy nodes. Otherwise their lookup will
- * return a logically removed node as insert position.
- */
- ht->cds_lfht_synchronize_rcu();
- /* Unlink and remove all now-unused dummy node pointers. */
- fini_table(ht, old_t, new_order, old_order - new_order);
- ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb);
+ /* Remove and unlink all dummy nodes to remove. */
+ fini_table(ht, new_order, old_order - new_order);
}
void _do_cds_lfht_resize(struct cds_lfht *ht)
{
unsigned long new_size, old_size;
- struct rcu_table *old_t;
-
- old_t = ht->t;
- old_size = old_t->size;
- new_size = CMM_LOAD_SHARED(old_t->resize_target);
- if (old_size < new_size)
- _do_cds_lfht_grow(ht, old_t, old_size, new_size);
- else if (old_size > new_size)
- _do_cds_lfht_shrink(ht, old_t, old_size, new_size);
- else
- CMM_STORE_SHARED(old_t->resize_initiated, 0);
+
+ /*
+ * Resize table, re-do if the target size has changed under us.
+ */
+ do {
+ ht->t.resize_initiated = 1;
+ old_size = ht->t.size;
+ new_size = CMM_LOAD_SHARED(ht->t.resize_target);
+ if (old_size < new_size)
+ _do_cds_lfht_grow(ht, old_size, new_size);
+ else if (old_size > new_size)
+ _do_cds_lfht_shrink(ht, old_size, new_size);
+ ht->t.resize_initiated = 0;
+ /* write resize_initiated before read resize_target */
+ cmm_smp_mb();
+ } while (ht->t.size != CMM_LOAD_SHARED(ht->t.resize_target));
}
static
-unsigned long resize_target_update(struct rcu_table *t,
+unsigned long resize_target_update(struct cds_lfht *ht, unsigned long size,
int growth_order)
{
- return _uatomic_max(&t->resize_target,
- t->size << growth_order);
+ return _uatomic_max(&ht->t.resize_target,
+ size << growth_order);
}
static
-void resize_target_update_count(struct rcu_table *t,
+void resize_target_update_count(struct cds_lfht *ht,
unsigned long count)
{
count = max(count, MIN_TABLE_SIZE);
- uatomic_set(&t->resize_target, count);
+ uatomic_set(&ht->t.resize_target, count);
}
void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
{
- struct rcu_table *t = rcu_dereference(ht->t);
-
- resize_target_update_count(t, new_size);
- CMM_STORE_SHARED(t->resize_initiated, 1);
+ resize_target_update_count(ht, new_size);
+ CMM_STORE_SHARED(ht->t.resize_initiated, 1);
+ ht->cds_lfht_rcu_thread_offline();
pthread_mutex_lock(&ht->resize_mutex);
_do_cds_lfht_resize(ht);
pthread_mutex_unlock(&ht->resize_mutex);
+ ht->cds_lfht_rcu_thread_online();
}
static
caa_container_of(head, struct rcu_resize_work, head);
struct cds_lfht *ht = work->ht;
+ ht->cds_lfht_rcu_thread_offline();
pthread_mutex_lock(&ht->resize_mutex);
_do_cds_lfht_resize(ht);
pthread_mutex_unlock(&ht->resize_mutex);
+ ht->cds_lfht_rcu_thread_online();
poison_free(work);
cmm_smp_mb(); /* finish resize before decrement */
uatomic_dec(&ht->in_progress_resize);
}
static
-void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth)
+void cds_lfht_resize_lazy(struct cds_lfht *ht, unsigned long size, int growth)
{
struct rcu_resize_work *work;
unsigned long target_size;
- target_size = resize_target_update(t, growth);
- if (!CMM_LOAD_SHARED(t->resize_initiated) && t->size < target_size) {
+ target_size = resize_target_update(ht, size, growth);
+ /* Store resize_target before read resize_initiated */
+ cmm_smp_mb();
+ if (!CMM_LOAD_SHARED(ht->t.resize_initiated) && size < target_size) {
uatomic_inc(&ht->in_progress_resize);
cmm_smp_mb(); /* increment resize count before calling it */
work = malloc(sizeof(*work));
work->ht = ht;
ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
- CMM_STORE_SHARED(t->resize_initiated, 1);
+ CMM_STORE_SHARED(ht->t.resize_initiated, 1);
}
}
#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
unsigned long count)
{
struct rcu_resize_work *work;
if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
return;
- resize_target_update_count(t, count);
- if (!CMM_LOAD_SHARED(t->resize_initiated)) {
+ resize_target_update_count(ht, count);
+ /* Store resize_target before read resize_initiated */
+ cmm_smp_mb();
+ if (!CMM_LOAD_SHARED(ht->t.resize_initiated)) {
uatomic_inc(&ht->in_progress_resize);
cmm_smp_mb(); /* increment resize count before calling it */
work = malloc(sizeof(*work));
work->ht = ht;
ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
- CMM_STORE_SHARED(t->resize_initiated, 1);
+ CMM_STORE_SHARED(ht->t.resize_initiated, 1);
}
}
projects / urcu.git / blobdiff