* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+/*
+ * Based on the following articles:
+ * - Ori Shalev and Nir Shavit. Split-ordered lists: Lock-free
+ * extensible hash tables. J. ACM 53, 3 (May 2006), 379-405.
+ * - Michael, M. M. High performance dynamic lock-free hash tables
+ * and list-based sets. In Proceedings of the fourteenth annual ACM
+ * symposium on Parallel algorithms and architectures, ACM Press,
+ * (2002), 73-82.
+ *
+ * Some specificities of this Lock-Free Expandable RCU Hash Table
+ * implementation:
+ *
+ * - RCU read-side critical section allows readers to perform hash
+ * table lookups and use the returned objects safely by delaying
+ * memory reclaim of a grace period.
+ * - Add and remove operations are lock-free, and do not need to
+ * allocate memory. They need to be executed within RCU read-side
+ * critical section to ensure the objects they read are valid and to
+ * deal with the cmpxchg ABA problem.
+ * - add and add_unique operations are supported. add_unique checks if
+ * the node key already exists in the hash table. It ensures no key
+ * duplicata exists.
+ * - The resize operation executes concurrently with add/remove/lookup.
+ * - Hash table nodes are contained within a split-ordered list. This
+ * list is ordered by incrementing reversed-bits-hash value.
+ * - An index of dummy nodes is kept. These dummy nodes are the hash
+ * table "buckets", and they are also chained together in the
+ * split-ordered list, which allows recursive expansion.
+ * - The resize operation only allows expanding the hash table.
+ * It is triggered either through an API call or automatically by
+ * detecting long chains in the add operation.
+ * - Resize operation initiated by long chain detection is executed by a
+ * call_rcu thread, which keeps lock-freedom of add and remove.
+ * - Resize operations are protected by a mutex.
+ * - The removal operation is split in two parts: first, a "removed"
+ * flag is set in the next pointer within the node to remove. Then,
+ * a "garbage collection" is performed in the bucket containing the
+ * removed node (from the start of the bucket up to the removed node).
+ * All encountered nodes with "removed" flag set in their next
+ * pointers are removed from the linked-list. If the cmpxchg used for
+ * removal fails (due to concurrent garbage-collection or concurrent
+ * add), we retry from the beginning of the bucket. This ensures that
+ * the node with "removed" flag set is removed from the hash table
+ * (not visible to lookups anymore) before the RCU read-side critical
+ * section held across removal ends. Furthermore, this ensures that
+ * the node with "removed" flag set is removed from the linked-list
+ * before its memory is reclaimed. Only the thread which removal
+ * successfully set the "removed" flag (with a cmpxchg) into a node's
+ * next pointer is considered to have succeeded its removal (and thus
+ * owns the node to reclaim). Because we garbage-collect starting from
+ * an invariant node (the start-of-bucket dummy node) up to the
+ * "removed" node (or find a reverse-hash that is higher), we are sure
+ * that a successful traversal of the chain leads to a chain that is
+ * present in the linked-list (the start node is never removed) and
+ * that is does not contain the "removed" node anymore, even if
+ * concurrent delete/add operations are changing the structure of the
+ * list concurrently.
+ * - The add operation performs gargage collection of buckets if it
+ * encounters nodes with removed flag set in the bucket where it wants
+ * to add its new node. This ensures lock-freedom of add operation by
+ * helping the remover unlink nodes from the list rather than to wait
+ * for it do to so.
+ * - A RCU "order table" indexed by log2(hash index) is copied and
+ * expanded by the resize operation. This order table allows finding
+ * 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.
+ * - 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.
+ */
+
#define _LGPL_SOURCE
#include <stdlib.h>
#include <errno.h>
#include <stdint.h>
#include <string.h>
+#include "config.h"
#include <urcu.h>
#include <urcu-call-rcu.h>
#include <urcu/arch.h>
#include <stdio.h>
#include <pthread.h>
-#define DEBUG /* Test */
-
#ifdef DEBUG
-#define dbg_printf(args...) printf(args)
+#define dbg_printf(fmt, args...) printf("[debug rculfhash] " fmt, ## args)
#else
-#define dbg_printf(args...)
+#define dbg_printf(fmt, args...)
#endif
+/*
+ * Per-CPU split-counters lazily update the global counter each 1024
+ * addition/removal. It automatically keeps track of resize required.
+ * We use the bucket length as indicator for need to expand for small
+ * tables and machines lacking per-cpu data suppport.
+ */
+#define COUNT_COMMIT_ORDER 10
#define CHAIN_LEN_TARGET 1
-#define CHAIN_LEN_RESIZE_THRESHOLD 2
+#define CHAIN_LEN_RESIZE_THRESHOLD 3
#ifndef max
#define max(a, b) ((a) > (b) ? (a) : (b))
#endif
+/*
+ * The removed flag needs to be updated atomically with the pointer.
+ * The dummy flag does not require to be updated atomically with the
+ * pointer, but it is added as a pointer low bit flag to save space.
+ */
+#define REMOVED_FLAG (1UL << 0)
+#define DUMMY_FLAG (1UL << 1)
+#define FLAGS_MASK ((1UL << 2) - 1)
+
+struct ht_items_count {
+ unsigned long add, remove;
+} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
+
struct rcu_table {
unsigned long size; /* always a power of 2 */
unsigned long resize_target;
int resize_initiated;
struct rcu_head head;
- struct rcu_ht_node *tbl[0];
+ struct _cds_lfht_node *tbl[0];
};
-struct rcu_ht {
+struct cds_lfht {
struct rcu_table *t; /* shared */
- ht_hash_fct hash_fct;
- ht_compare_fct compare_fct;
+ cds_lfht_hash_fct hash_fct;
+ cds_lfht_compare_fct compare_fct;
unsigned long hash_seed;
pthread_mutex_t resize_mutex; /* resize mutex: add/del mutex */
- unsigned int in_progress_resize;
- void (*ht_call_rcu)(struct rcu_head *head,
+ unsigned int in_progress_resize, in_progress_destroy;
+ void (*cds_lfht_call_rcu)(struct rcu_head *head,
void (*func)(struct rcu_head *head));
+ unsigned long count; /* global approximate item count */
+ struct ht_items_count *percpu_count; /* per-cpu item count */
};
struct rcu_resize_work {
struct rcu_head head;
- struct rcu_ht *ht;
+ struct cds_lfht *ht;
};
/*
}
/*
- * Algorithm to find the log2 of a 32-bit unsigned integer.
- * source: http://graphics.stanford.edu/~seander/bithacks.html#IntegerLogLookup
- * Originally from Public Domain.
+ * fls: returns the position of the most significant bit.
+ * Returns 0 if no bit is set, else returns the position of the most
+ * significant bit (from 1 to 32 on 32-bit, from 1 to 64 on 64-bit).
*/
-static const char LogTable256[256] =
+#if defined(__i386) || defined(__x86_64)
+static inline
+unsigned int fls_u32(uint32_t x)
{
-#define LT(n) n, n, n, n, n, n, n, n, n, n, n, n, n, n, n, n
- -1, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3,
- LT(4), LT(5), LT(5), LT(6), LT(6), LT(6), LT(6),
- LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7), LT(7)
-};
+ int r;
+
+ asm("bsrl %1,%0\n\t"
+ "jnz 1f\n\t"
+ "movl $-1,%0\n\t"
+ "1:\n\t"
+ : "=r" (r) : "rm" (x));
+ return r + 1;
+}
+#define HAS_FLS_U32
+#endif
+
+#if defined(__x86_64)
+static inline
+unsigned int fls_u64(uint64_t x)
+{
+ long r;
+
+ asm("bsrq %1,%0\n\t"
+ "jnz 1f\n\t"
+ "movq $-1,%0\n\t"
+ "1:\n\t"
+ : "=r" (r) : "rm" (x));
+ return r + 1;
+}
+#define HAS_FLS_U64
+#endif
+
+#ifndef HAS_FLS_U64
+static __attribute__((unused))
+unsigned int fls_u64(uint64_t x)
+{
+ unsigned int r = 64;
+
+ if (!x)
+ return 0;
+
+ if (!(x & 0xFFFFFFFF00000000ULL)) {
+ x <<= 32;
+ r -= 32;
+ }
+ if (!(x & 0xFFFF000000000000ULL)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xFF00000000000000ULL)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xF000000000000000ULL)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xC000000000000000ULL)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x8000000000000000ULL)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+#endif
+
+#ifndef HAS_FLS_U32
+static __attribute__((unused))
+unsigned int fls_u32(uint32_t x)
+{
+ unsigned int r = 32;
+
+ if (!x)
+ return 0;
+ if (!(x & 0xFFFF0000U)) {
+ x <<= 16;
+ r -= 16;
+ }
+ if (!(x & 0xFF000000U)) {
+ x <<= 8;
+ r -= 8;
+ }
+ if (!(x & 0xF0000000U)) {
+ x <<= 4;
+ r -= 4;
+ }
+ if (!(x & 0xC0000000U)) {
+ x <<= 2;
+ r -= 2;
+ }
+ if (!(x & 0x80000000U)) {
+ x <<= 1;
+ r -= 1;
+ }
+ return r;
+}
+#endif
+
+unsigned int fls_ulong(unsigned long x)
+{
+#if (CAA_BITS_PER_lONG == 32)
+ return fls_u32(x);
+#else
+ return fls_u64(x);
+#endif
+}
-uint32_t log2_u32(uint32_t v)
+int get_count_order_u32(uint32_t x)
{
- uint32_t t, tt;
+ int order;
+
+ order = fls_u32(x) - 1;
+ if (x & (x - 1))
+ order++;
+ return order;
+}
+
+int get_count_order_ulong(unsigned long x)
+{
+ int order;
+
+ order = fls_ulong(x) - 1;
+ if (x & (x - 1))
+ order++;
+ return order;
+}
+
+static
+void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth);
+
+/*
+ * If the sched_getcpu() and sysconf(_SC_NPROCESSORS_CONF) calls are
+ * available, then we support hash table item accounting.
+ * In the unfortunate event the number of CPUs reported would be
+ * inaccurate, we use modulo arithmetic on the number of CPUs we got.
+ */
+#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
+
+static
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+ unsigned long count);
+
+static long nr_cpus_mask = -1;
+
+static
+struct ht_items_count *alloc_per_cpu_items_count(void)
+{
+ struct ht_items_count *count;
+
+ switch (nr_cpus_mask) {
+ case -2:
+ return NULL;
+ case -1:
+ {
+ long maxcpus;
+
+ maxcpus = sysconf(_SC_NPROCESSORS_CONF);
+ if (maxcpus <= 0) {
+ nr_cpus_mask = -2;
+ return NULL;
+ }
+ /*
+ * round up number of CPUs to next power of two, so we
+ * can use & for modulo.
+ */
+ maxcpus = 1UL << get_count_order_ulong(maxcpus);
+ nr_cpus_mask = maxcpus - 1;
+ }
+ /* Fall-through */
+ default:
+ return calloc(nr_cpus_mask + 1, sizeof(*count));
+ }
+}
- if ((tt = (v >> 16)))
- return (t = (tt >> 8))
- ? 24 + LogTable256[t]
- : 16 + LogTable256[tt];
+static
+void free_per_cpu_items_count(struct ht_items_count *count)
+{
+ free(count);
+}
+
+static
+int ht_get_cpu(void)
+{
+ int cpu;
+
+ assert(nr_cpus_mask >= 0);
+ cpu = sched_getcpu();
+ if (unlikely(cpu < 0))
+ return cpu;
else
- return (t = (v >> 8))
- ? 8 + LogTable256[t]
- : LogTable256[v];
+ return cpu & nr_cpus_mask;
}
static
-void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth);
+void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
+{
+ unsigned long percpu_count;
+ int cpu;
+
+ if (unlikely(!ht->percpu_count))
+ return;
+ cpu = ht_get_cpu();
+ if (unlikely(cpu < 0))
+ return;
+ percpu_count = uatomic_add_return(&ht->percpu_count[cpu].add, 1);
+ if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+ unsigned long count;
+
+ dbg_printf("add percpu %lu\n", percpu_count);
+ count = uatomic_add_return(&ht->count,
+ 1UL << COUNT_COMMIT_ORDER);
+ /* If power of 2 */
+ if (!(count & (count - 1))) {
+ if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
+ < t->size)
+ return;
+ dbg_printf("add set global %lu\n", count);
+ cds_lfht_resize_lazy_count(ht, t,
+ count >> (CHAIN_LEN_TARGET - 1));
+ }
+ }
+}
static
-void check_resize(struct rcu_ht *ht, struct rcu_table *t,
+void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
+{
+ unsigned long percpu_count;
+ int cpu;
+
+ if (unlikely(!ht->percpu_count))
+ return;
+ cpu = ht_get_cpu();
+ if (unlikely(cpu < 0))
+ return;
+ percpu_count = uatomic_add_return(&ht->percpu_count[cpu].remove, -1);
+ if (unlikely(!(percpu_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+ unsigned long count;
+
+ dbg_printf("remove percpu %lu\n", percpu_count);
+ count = uatomic_add_return(&ht->count,
+ -(1UL << COUNT_COMMIT_ORDER));
+ /* If power of 2 */
+ if (!(count & (count - 1))) {
+ if ((count >> CHAIN_LEN_RESIZE_THRESHOLD)
+ >= t->size)
+ return;
+ dbg_printf("remove set global %lu\n", count);
+ cds_lfht_resize_lazy_count(ht, t,
+ count >> (CHAIN_LEN_TARGET - 1));
+ }
+ }
+}
+
+#else /* #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
+
+static const long nr_cpus_mask = -1;
+
+static
+struct ht_items_count *alloc_per_cpu_items_count(void)
+{
+ return NULL;
+}
+
+static
+void free_per_cpu_items_count(struct ht_items_count *count)
+{
+}
+
+static
+void ht_count_add(struct cds_lfht *ht, struct rcu_table *t)
+{
+}
+
+static
+void ht_count_remove(struct cds_lfht *ht, struct rcu_table *t)
+{
+}
+
+#endif /* #else #if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF) */
+
+
+static
+void check_resize(struct cds_lfht *ht, struct rcu_table *t,
uint32_t chain_len)
{
+ unsigned long count;
+
+ count = uatomic_read(&ht->count);
+ /*
+ * Use bucket-local length for small table expand and for
+ * environments lacking per-cpu data support.
+ */
+ if (count >= (1UL << COUNT_COMMIT_ORDER))
+ return;
+ if (chain_len > 100)
+ dbg_printf("WARNING: large chain length: %u.\n",
+ chain_len);
if (chain_len >= CHAIN_LEN_RESIZE_THRESHOLD)
- ht_resize_lazy(ht, t,
- log2_u32(chain_len - CHAIN_LEN_TARGET - 1));
+ cds_lfht_resize_lazy(ht, t,
+ get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
}
static
-struct rcu_ht_node *clear_flag(struct rcu_ht_node *node)
+struct cds_lfht_node *clear_flag(struct cds_lfht_node *node)
{
- return (struct rcu_ht_node *) (((unsigned long) node) & ~0x1);
+ return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK);
}
static
-int is_removed(struct rcu_ht_node *node)
+int is_removed(struct cds_lfht_node *node)
{
- return ((unsigned long) node) & 0x1;
+ return ((unsigned long) node) & REMOVED_FLAG;
}
static
-struct rcu_ht_node *flag_removed(struct rcu_ht_node *node)
+struct cds_lfht_node *flag_removed(struct cds_lfht_node *node)
{
- return (struct rcu_ht_node *) (((unsigned long) node) | 0x1);
+ return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG);
}
+static
+int is_dummy(struct cds_lfht_node *node)
+{
+ return ((unsigned long) node) & DUMMY_FLAG;
+}
+
+static
+struct cds_lfht_node *flag_dummy(struct cds_lfht_node *node)
+{
+ return (struct cds_lfht_node *) (((unsigned long) node) | DUMMY_FLAG);
+}
+
static
unsigned long _uatomic_max(unsigned long *ptr, unsigned long v)
{
* Remove all logically deleted nodes from a bucket up to a certain node key.
*/
static
-void _ht_gc_bucket(struct rcu_ht_node *dummy, struct rcu_ht_node *node)
+void _cds_lfht_gc_bucket(struct cds_lfht_node *dummy, struct cds_lfht_node *node)
{
- struct rcu_ht_node *iter_prev, *iter, *next;
+ struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
for (;;) {
iter_prev = dummy;
iter = rcu_dereference(iter_prev->p.next);
assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
for (;;) {
- if (unlikely(!iter))
+ if (unlikely(!clear_flag(iter)))
return;
- if (clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)
+ if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
return;
next = rcu_dereference(clear_flag(iter)->p.next);
- if (is_removed(next))
+ if (likely(is_removed(next)))
break;
- iter_prev = iter;
+ iter_prev = clear_flag(iter);
iter = next;
}
assert(!is_removed(iter));
- (void) uatomic_cmpxchg(&iter_prev->p.next, iter, clear_flag(next));
+ if (is_dummy(iter))
+ new_next = flag_dummy(clear_flag(next));
+ else
+ new_next = clear_flag(next);
+ (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
}
}
static
-struct rcu_ht_node *_ht_add(struct rcu_ht *ht, struct rcu_table *t,
- struct rcu_ht_node *node, int unique)
+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 rcu_ht_node *iter_prev, *dummy, *iter, *next;
- unsigned long hash;
+ struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
+ *dummy_node;
+ struct _cds_lfht_node *lookup;
+ unsigned long hash, index, order;
if (!t->size) {
- assert(node->p.dummy);
+ assert(dummy);
+ node->p.next = flag_dummy(NULL);
return node; /* Initial first add (head) */
}
hash = bit_reverse_ulong(node->p.reverse_hash);
* iter_prev points to the non-removed node prior to the
* insert location.
*/
- iter_prev = rcu_dereference(t->tbl[hash & (t->size - 1)]);
+ index = hash & (t->size - 1);
+ order = get_count_order_ulong(index + 1);
+ lookup = &t->tbl[order][index & ((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);
assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
for (;;) {
- if (unlikely(!iter))
+ if (unlikely(!clear_flag(iter)))
goto insert;
- if (clear_flag(iter)->p.reverse_hash > node->p.reverse_hash)
+ if (likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
goto insert;
next = rcu_dereference(clear_flag(iter)->p.next);
- if (is_removed(next))
+ if (unlikely(is_removed(next)))
goto gc_node;
if (unique
- && !clear_flag(iter)->p.dummy
+ && !is_dummy(next)
&& !ht->compare_fct(node->key, node->key_len,
clear_flag(iter)->key,
clear_flag(iter)->key_len))
return clear_flag(iter);
/* Only account for identical reverse hash once */
- if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash)
+ if (iter_prev->p.reverse_hash != clear_flag(iter)->p.reverse_hash
+ && !is_dummy(next))
check_resize(ht, t, ++chain_len);
iter_prev = clear_flag(iter);
iter = next;
assert(node != clear_flag(iter));
assert(!is_removed(iter_prev));
assert(iter_prev != node);
- node->p.next = iter;
+ if (!dummy)
+ node->p.next = clear_flag(iter);
+ else
+ node->p.next = flag_dummy(clear_flag(iter));
+ if (is_dummy(iter))
+ new_node = flag_dummy(node);
+ else
+ new_node = node;
if (uatomic_cmpxchg(&iter_prev->p.next, iter,
- node) != iter)
+ new_node) != iter)
continue; /* retry */
else
goto gc_end;
gc_node:
assert(!is_removed(iter));
- (void) uatomic_cmpxchg(&iter_prev->p.next, iter, clear_flag(next));
+ if (is_dummy(iter))
+ new_next = flag_dummy(clear_flag(next));
+ else
+ new_next = clear_flag(next);
+ (void) uatomic_cmpxchg(&iter_prev->p.next, iter, new_next);
/* retry */
}
gc_end:
/* Garbage collect logically removed nodes in the bucket */
- dummy = rcu_dereference(t->tbl[hash & (t->size - 1)]);
- _ht_gc_bucket(dummy, node);
+ index = hash & (t->size - 1);
+ order = get_count_order_ulong(index + 1);
+ lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)];
+ dummy_node = (struct cds_lfht_node *) lookup;
+ _cds_lfht_gc_bucket(dummy_node, node);
return node;
}
static
-int _ht_remove(struct rcu_ht *ht, struct rcu_table *t, struct rcu_ht_node *node)
+int _cds_lfht_remove(struct cds_lfht *ht, struct rcu_table *t,
+ struct cds_lfht_node *node)
{
- struct rcu_ht_node *dummy, *next, *old;
+ struct cds_lfht_node *dummy, *next, *old;
+ struct _cds_lfht_node *lookup;
int flagged = 0;
- unsigned long hash;
+ unsigned long hash, index, order;
/* logically delete the node */
old = rcu_dereference(node->p.next);
do {
next = old;
- if (is_removed(next))
+ if (unlikely(is_removed(next)))
goto end;
- assert(!node->p.dummy);
+ assert(!is_dummy(next));
old = uatomic_cmpxchg(&node->p.next, next,
flag_removed(next));
} while (old != next);
* if found.
*/
hash = bit_reverse_ulong(node->p.reverse_hash);
- dummy = rcu_dereference(t->tbl[hash & (t->size - 1)]);
- _ht_gc_bucket(dummy, node);
+ index = hash & (t->size - 1);
+ order = get_count_order_ulong(index + 1);
+ lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)];
+ dummy = (struct cds_lfht_node *) lookup;
+ _cds_lfht_gc_bucket(dummy, node);
end:
/*
* Only the flagging action indicated that we (and no other)
}
static
-void init_table(struct rcu_ht *ht, struct rcu_table *t,
- unsigned long first, unsigned long len)
+void init_table(struct cds_lfht *ht, struct rcu_table *t,
+ unsigned long first_order, unsigned long len_order)
{
- unsigned long i, end;
-
- end = first + len;
- for (i = first; i < end; i++) {
- /* Update table size when power of two */
- if (i != 0 && !(i & (i - 1)))
- t->size = i;
- t->tbl[i] = calloc(1, sizeof(struct _rcu_ht_node));
- t->tbl[i]->p.dummy = 1;
- t->tbl[i]->p.reverse_hash = bit_reverse_ulong(i);
- (void) _ht_add(ht, t, t->tbl[i], 0);
+ 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;
+
+ len = !i ? 1 : 1UL << (i - 1);
+ dbg_printf("init order %lu len: %lu\n", i, len);
+ t->tbl[i] = calloc(len, sizeof(struct _cds_lfht_node));
+ for (j = 0; j < len; j++) {
+ dbg_printf("init entry: i %lu j %lu hash %lu\n",
+ i, j, !i ? 0 : (1UL << (i - 1)) + j);
+ struct cds_lfht_node *new_node =
+ (struct cds_lfht_node *) &t->tbl[i][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;
+ }
+ /* Update table size */
+ t->size = !i ? 1 : (1UL << i);
+ dbg_printf("init new size: %lu\n", t->size);
+ if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+ break;
}
- t->resize_target = t->size = end;
+ t->resize_target = t->size;
t->resize_initiated = 0;
}
-struct rcu_ht *ht_new(ht_hash_fct hash_fct,
- ht_compare_fct compare_fct,
- unsigned long hash_seed,
- unsigned long init_size,
- void (*ht_call_rcu)(struct rcu_head *head,
- void (*func)(struct rcu_head *head)))
+struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
+ cds_lfht_compare_fct compare_fct,
+ unsigned long hash_seed,
+ unsigned long init_size,
+ void (*cds_lfht_call_rcu)(struct rcu_head *head,
+ void (*func)(struct rcu_head *head)))
{
- struct rcu_ht *ht;
+ struct cds_lfht *ht;
+ unsigned long order;
- ht = calloc(1, sizeof(struct rcu_ht));
+ /* init_size must be power of two */
+ if (init_size && (init_size & (init_size - 1)))
+ return NULL;
+ ht = calloc(1, sizeof(struct cds_lfht));
ht->hash_fct = hash_fct;
ht->compare_fct = compare_fct;
ht->hash_seed = hash_seed;
- ht->ht_call_rcu = ht_call_rcu;
+ ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
ht->in_progress_resize = 0;
+ 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);
- ht->t = calloc(1, sizeof(struct rcu_table)
- + (max(init_size, 1) * sizeof(struct rcu_ht_node *)));
+ order = get_count_order_ulong(max(init_size, 1)) + 1;
+ ht->t = calloc(1, sizeof(struct cds_lfht)
+ + (order * sizeof(struct _cds_lfht_node *)));
ht->t->size = 0;
pthread_mutex_lock(&ht->resize_mutex);
- init_table(ht, ht->t, 0, max(init_size, 1));
+ init_table(ht, ht->t, 0, order);
pthread_mutex_unlock(&ht->resize_mutex);
return ht;
}
-struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len)
+struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len)
{
struct rcu_table *t;
- struct rcu_ht_node *node;
- unsigned long hash, reverse_hash;
+ struct cds_lfht_node *node, *next;
+ struct _cds_lfht_node *lookup;
+ unsigned long hash, reverse_hash, index, order;
hash = ht->hash_fct(key, key_len, ht->hash_seed);
reverse_hash = bit_reverse_ulong(hash);
t = rcu_dereference(ht->t);
- node = rcu_dereference(t->tbl[hash & (t->size - 1)]);
+ index = hash & (t->size - 1);
+ order = get_count_order_ulong(index + 1);
+ lookup = &t->tbl[order][index & ((1UL << (order - 1)) - 1)];
+ dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
+ hash, index, order, index & ((1UL << (order - 1)) - 1));
+ node = (struct cds_lfht_node *) lookup;
for (;;) {
if (unlikely(!node))
break;
node = NULL;
break;
}
- if (likely(!is_removed(rcu_dereference(node->p.next)))
- && !node->p.dummy
+ next = rcu_dereference(node->p.next);
+ if (likely(!is_removed(next))
+ && !is_dummy(next)
&& likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
break;
}
- node = clear_flag(rcu_dereference(node->p.next));
+ node = clear_flag(next);
}
- assert(!node || !node->p.dummy);
+ assert(!node || !is_dummy(rcu_dereference(node->p.next)));
return node;
}
-void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node)
+struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht,
+ struct cds_lfht_node *node)
+{
+ struct cds_lfht_node *next;
+ unsigned long reverse_hash;
+ void *key;
+ size_t key_len;
+
+ reverse_hash = node->p.reverse_hash;
+ key = node->key;
+ key_len = node->key_len;
+ next = rcu_dereference(node->p.next);
+ node = clear_flag(next);
+
+ for (;;) {
+ if (unlikely(!node))
+ break;
+ if (unlikely(node->p.reverse_hash > reverse_hash)) {
+ node = NULL;
+ break;
+ }
+ next = rcu_dereference(node->p.next);
+ if (likely(!is_removed(next))
+ && !is_dummy(next)
+ && likely(!ht->compare_fct(node->key, node->key_len, key, key_len))) {
+ break;
+ }
+ node = clear_flag(next);
+ }
+ assert(!node || !is_dummy(rcu_dereference(node->p.next)));
+ return node;
+}
+
+void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node)
{
struct rcu_table *t;
unsigned long hash;
node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
t = rcu_dereference(ht->t);
- (void) _ht_add(ht, t, node, 0);
+ (void) _cds_lfht_add(ht, t, node, 0, 0);
+ ht_count_add(ht, t);
}
-struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node)
+struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+ struct cds_lfht_node *node)
{
struct rcu_table *t;
unsigned long hash;
+ 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);
- return _ht_add(ht, t, node, 1);
+ ret = _cds_lfht_add(ht, t, node, 1, 0);
+ if (ret != node)
+ ht_count_add(ht, t);
+ return ret;
}
-int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node)
+int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node)
{
struct rcu_table *t;
+ int ret;
t = rcu_dereference(ht->t);
- return _ht_remove(ht, t, node);
+ ret = _cds_lfht_remove(ht, t, node);
+ if (!ret)
+ ht_count_remove(ht, t);
+ return ret;
}
static
-int ht_delete_dummy(struct rcu_ht *ht)
+int cds_lfht_delete_dummy(struct cds_lfht *ht)
{
struct rcu_table *t;
- struct rcu_ht_node *node;
- unsigned long i;
+ struct cds_lfht_node *node;
+ struct _cds_lfht_node *lookup;
+ unsigned long order, i;
t = ht->t;
/* Check that the table is empty */
- node = t->tbl[0];
+ lookup = &t->tbl[0][0];
+ node = (struct cds_lfht_node *) lookup;
do {
- if (!node->p.dummy)
+ node = clear_flag(node)->p.next;
+ if (!is_dummy(node))
return -EPERM;
- node = node->p.next;
assert(!is_removed(node));
- } while (node);
+ } while (clear_flag(node));
/* Internal sanity check: all nodes left should be dummy */
- for (i = 0; i < t->size; i++) {
- assert(t->tbl[i]->p.dummy);
- free(t->tbl[i]);
+ for (order = 0; order < get_count_order_ulong(t->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][i].reverse_hash));
+ assert(is_dummy(t->tbl[order][i].next));
+ }
+ free(t->tbl[order]);
}
return 0;
}
* Should only be called when no more concurrent readers nor writers can
* possibly access the table.
*/
-int ht_destroy(struct rcu_ht *ht)
+int cds_lfht_destroy(struct cds_lfht *ht)
{
int ret;
/* Wait for in-flight resize operations to complete */
+ CMM_STORE_SHARED(ht->in_progress_destroy, 1);
while (uatomic_read(&ht->in_progress_resize))
poll(NULL, 0, 100); /* wait for 100ms */
- ret = ht_delete_dummy(ht);
+ ret = cds_lfht_delete_dummy(ht);
if (ret)
return ret;
free(ht->t);
+ free_per_cpu_items_count(ht->percpu_count);
free(ht);
return ret;
}
-void ht_count_nodes(struct rcu_ht *ht,
+void cds_lfht_count_nodes(struct cds_lfht *ht,
unsigned long *count,
unsigned long *removed)
{
struct rcu_table *t;
- struct rcu_ht_node *node, *next;
+ 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);
- /* Check that the table is empty */
- node = rcu_dereference(t->tbl[0]);
+ /* Count non-dummy nodes in the table */
+ lookup = &t->tbl[0][0];
+ node = (struct cds_lfht_node *) lookup;
do {
next = rcu_dereference(node->p.next);
if (is_removed(next)) {
- assert(!node->p.dummy);
+ assert(!is_dummy(next));
(*removed)++;
- } else if (!node->p.dummy)
+ } else if (!is_dummy(next))
(*count)++;
+ else
+ (nr_dummy)++;
node = clear_flag(next);
} while (node);
+ dbg_printf("number of dummy nodes: %lu\n", nr_dummy);
}
static
-void ht_free_table_cb(struct rcu_head *head)
+void cds_lfht_free_table_cb(struct rcu_head *head)
{
struct rcu_table *t =
caa_container_of(head, struct rcu_table, head);
/* called with resize mutex held */
static
-void _do_ht_resize(struct rcu_ht *ht)
+void _do_cds_lfht_resize(struct cds_lfht *ht)
{
- unsigned long new_size, old_size;
+ unsigned long new_size, old_size, old_order, new_order;
struct rcu_table *new_t, *old_t;
old_t = ht->t;
old_size = old_t->size;
+ old_order = get_count_order_ulong(old_size) + 1;
new_size = CMM_LOAD_SHARED(old_t->resize_target);
- dbg_printf("rculfhash: resize from %lu to %lu buckets\n",
- old_size, new_size);
if (old_size == new_size)
return;
- new_t = malloc(sizeof(struct rcu_table)
- + (new_size * sizeof(struct rcu_ht_node *)));
+ 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 _cds_lfht_node *)));
assert(new_size > old_size);
memcpy(&new_t->tbl, &old_t->tbl,
- old_size * sizeof(struct rcu_ht_node *));
- init_table(ht, new_t, old_size, new_size - old_size);
+ old_order * sizeof(struct _cds_lfht_node *));
+ 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->ht_call_rcu(&old_t->head, ht_free_table_cb);
+ ht->cds_lfht_call_rcu(&old_t->head, cds_lfht_free_table_cb);
}
static
t->size << growth_order);
}
-void ht_resize(struct rcu_ht *ht, int growth)
+void cds_lfht_resize(struct cds_lfht *ht, int growth)
{
struct rcu_table *t = rcu_dereference(ht->t);
unsigned long target_size;
+ if (growth < 0) {
+ /*
+ * Silently refuse to shrink hash table. (not supported)
+ */
+ dbg_printf("shrinking hash table not supported.\n");
+ return;
+ }
+
target_size = resize_target_update(t, growth);
if (t->size < target_size) {
CMM_STORE_SHARED(t->resize_initiated, 1);
pthread_mutex_lock(&ht->resize_mutex);
- _do_ht_resize(ht);
+ _do_cds_lfht_resize(ht);
pthread_mutex_unlock(&ht->resize_mutex);
}
}
{
struct rcu_resize_work *work =
caa_container_of(head, struct rcu_resize_work, head);
- struct rcu_ht *ht = work->ht;
+ struct cds_lfht *ht = work->ht;
pthread_mutex_lock(&ht->resize_mutex);
- _do_ht_resize(ht);
+ _do_cds_lfht_resize(ht);
pthread_mutex_unlock(&ht->resize_mutex);
free(work);
cmm_smp_mb(); /* finish resize before decrement */
}
static
-void ht_resize_lazy(struct rcu_ht *ht, struct rcu_table *t, int growth)
+void cds_lfht_resize_lazy(struct cds_lfht *ht, struct rcu_table *t, int growth)
{
struct rcu_resize_work *work;
unsigned long target_size;
cmm_smp_mb(); /* increment resize count before calling it */
work = malloc(sizeof(*work));
work->ht = ht;
- ht->ht_call_rcu(&work->head, do_resize_cb);
+ ht->cds_lfht_call_rcu(&work->head, do_resize_cb);
+ CMM_STORE_SHARED(t->resize_initiated, 1);
+ }
+}
+
+#if defined(HAVE_SCHED_GETCPU) && defined(HAVE_SYSCONF)
+
+static
+unsigned long resize_target_update_count(struct rcu_table *t,
+ unsigned long count)
+{
+ return uatomic_set(&t->resize_target, count);
+}
+
+static
+void cds_lfht_resize_lazy_count(struct cds_lfht *ht, struct rcu_table *t,
+ unsigned long count)
+{
+ struct rcu_resize_work *work;
+ unsigned long target_size;
+
+ target_size = resize_target_update_count(t, count);
+ if (!CMM_LOAD_SHARED(t->resize_initiated) && t->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);
}
}
+
+#endif
projects / urcu.git / blobdiff