+++ /dev/null
-/*
- * rculfhash.c
- *
- * Userspace RCU library - Lock-Free Resizable RCU Hash Table
- *
- * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * 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 Resizable 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 bucket nodes is kept. These bucket nodes are the hash
- * table "buckets", and they are also chained together in the
- * split-ordered list, which allows recursive expansion.
- * - The resize operation for small tables only allows expanding the hash table.
- * It is triggered automatically by detecting long chains in the add
- * operation.
- * - The resize operation for larger tables (and available through an
- * API) allows both expanding and shrinking the hash table.
- * - Split-counters are used to keep track of the number of
- * nodes within the hash table for automatic resize triggering.
- * - 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 bucket 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 "bucket node" tables.
- * - There is one bucket node table per hash index order. The size of
- * each bucket node table is half the number of hashes contained in
- * this order (except for order 0).
- * - synchronzie_rcu is used to garbage-collect the old bucket node table.
- * - The per-order bucket node tables contain a compact version of the
- * hash table nodes. These tables are invariant after they are
- * populated into the hash table.
- *
- * Bucket node tables:
- *
- * hash table hash table the last all bucket node tables
- * order size bucket 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 bucket 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 bucket node table
- * shrink hash table from order 6 to 5: fini the index=6 bucket node table
- *
- * A bit of ascii art explanation:
- *
- * Order index is the off-by-one compare to the actual power of 2 because
- * we use index 0 to deal with the 0 special-case.
- *
- * This shows the nodes for a small table ordered by reversed bits:
- *
- * bits reverse
- * 0 000 000
- * 4 100 001
- * 2 010 010
- * 6 110 011
- * 1 001 100
- * 5 101 101
- * 3 011 110
- * 7 111 111
- *
- * This shows the nodes in order of non-reversed bits, linked by
- * reversed-bit order.
- *
- * order bits reverse
- * 0 0 000 000
- * 1 | 1 001 100 <-
- * 2 | | 2 010 010 <- |
- * | | | 3 011 110 | <- |
- * 3 -> | | | 4 100 001 | |
- * -> | | 5 101 101 |
- * -> | 6 110 011
- * -> 7 111 111
- */
-
-#define _LGPL_SOURCE
-#include <stdlib.h>
-#include <errno.h>
-#include <assert.h>
-#include <stdio.h>
-#include <stdint.h>
-#include <string.h>
-
-#include "config.h"
-#include <urcu.h>
-#include <urcu-call-rcu.h>
-#include <urcu/arch.h>
-#include <urcu/uatomic.h>
-#include <urcu/compiler.h>
-#include <stdio.h>
-#include <pthread.h>
-
-#include "rculfhash.h"
-#include "rculfhash-internal.h"
-#include "urcu-flavor.h"
-
-/*
- * 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 DEFAULT_SPLIT_COUNT_MASK 0xFUL
-#define CHAIN_LEN_TARGET 1
-#define CHAIN_LEN_RESIZE_THRESHOLD 3
-
-/*
- * Define the minimum table size.
- */
-#define MIN_TABLE_ORDER 0
-#define MIN_TABLE_SIZE (1UL << MIN_TABLE_ORDER)
-
-/*
- * Minimum number of bucket nodes to touch per thread to parallelize grow/shrink.
- */
-#define MIN_PARTITION_PER_THREAD_ORDER 12
-#define MIN_PARTITION_PER_THREAD (1UL << MIN_PARTITION_PER_THREAD_ORDER)
-
-/*
- * The removed flag needs to be updated atomically with the pointer.
- * It indicates that no node must attach to the node scheduled for
- * removal, and that node garbage collection must be performed.
- * The bucket 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 BUCKET_FLAG (1UL << 1)
-#define REMOVAL_OWNER_FLAG (1UL << 2)
-#define FLAGS_MASK ((1UL << 3) - 1)
-
-/* Value of the end pointer. Should not interact with flags. */
-#define END_VALUE NULL
-
-DEFINE_RCU_FLAVOR(rcu_flavor);
-
-/*
- * ht_items_count: Split-counters counting the number of node addition
- * and removal in the table. Only used if the CDS_LFHT_ACCOUNTING flag
- * is set at hash table creation.
- *
- * These are free-running counters, never reset to zero. They count the
- * number of add/remove, and trigger every (1 << COUNT_COMMIT_ORDER)
- * operations to update the global counter. We choose a power-of-2 value
- * for the trigger to deal with 32 or 64-bit overflow of the counter.
- */
-struct ht_items_count {
- unsigned long add, del;
-} __attribute__((aligned(CAA_CACHE_LINE_SIZE)));
-
-/*
- * rcu_resize_work: Contains arguments passed to RCU worker thread
- * responsible for performing lazy resize.
- */
-struct rcu_resize_work {
- struct rcu_head head;
- struct cds_lfht *ht;
-};
-
-/*
- * partition_resize_work: Contains arguments passed to worker threads
- * executing the hash table resize on partitions of the hash table
- * assigned to each processor's worker thread.
- */
-struct partition_resize_work {
- pthread_t thread_id;
- struct cds_lfht *ht;
- unsigned long i, start, len;
- void (*fct)(struct cds_lfht *ht, unsigned long i,
- unsigned long start, unsigned long len);
-};
-
-/*
- * Algorithm to reverse bits in a word by lookup table, extended to
- * 64-bit words.
- * Source:
- * http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
- * Originally from Public Domain.
- */
-
-static const uint8_t BitReverseTable256[256] =
-{
-#define R2(n) (n), (n) + 2*64, (n) + 1*64, (n) + 3*64
-#define R4(n) R2(n), R2((n) + 2*16), R2((n) + 1*16), R2((n) + 3*16)
-#define R6(n) R4(n), R4((n) + 2*4 ), R4((n) + 1*4 ), R4((n) + 3*4 )
- R6(0), R6(2), R6(1), R6(3)
-};
-#undef R2
-#undef R4
-#undef R6
-
-static
-uint8_t bit_reverse_u8(uint8_t v)
-{
- return BitReverseTable256[v];
-}
-
-static __attribute__((unused))
-uint32_t bit_reverse_u32(uint32_t v)
-{
- return ((uint32_t) bit_reverse_u8(v) << 24) |
- ((uint32_t) bit_reverse_u8(v >> 8) << 16) |
- ((uint32_t) bit_reverse_u8(v >> 16) << 8) |
- ((uint32_t) bit_reverse_u8(v >> 24));
-}
-
-static __attribute__((unused))
-uint64_t bit_reverse_u64(uint64_t v)
-{
- return ((uint64_t) bit_reverse_u8(v) << 56) |
- ((uint64_t) bit_reverse_u8(v >> 8) << 48) |
- ((uint64_t) bit_reverse_u8(v >> 16) << 40) |
- ((uint64_t) bit_reverse_u8(v >> 24) << 32) |
- ((uint64_t) bit_reverse_u8(v >> 32) << 24) |
- ((uint64_t) bit_reverse_u8(v >> 40) << 16) |
- ((uint64_t) bit_reverse_u8(v >> 48) << 8) |
- ((uint64_t) bit_reverse_u8(v >> 56));
-}
-
-static
-unsigned long bit_reverse_ulong(unsigned long v)
-{
-#if (CAA_BITS_PER_LONG == 32)
- return bit_reverse_u32(v);
-#else
- return bit_reverse_u64(v);
-#endif
-}
-
-/*
- * 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).
- */
-#if defined(__i386) || defined(__x86_64)
-static inline
-unsigned int fls_u32(uint32_t x)
-{
- 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 cds_lfht_fls_ulong(unsigned long x)
-{
-#if (CAA_BITS_PER_LONG == 32)
- return fls_u32(x);
-#else
- return fls_u64(x);
-#endif
-}
-
-/*
- * Return the minimum order for which x <= (1UL << order).
- * Return -1 if x is 0.
- */
-int cds_lfht_get_count_order_u32(uint32_t x)
-{
- if (!x)
- return -1;
-
- return fls_u32(x - 1);
-}
-
-/*
- * Return the minimum order for which x <= (1UL << order).
- * Return -1 if x is 0.
- */
-int cds_lfht_get_count_order_ulong(unsigned long x)
-{
- if (!x)
- return -1;
-
- return cds_lfht_fls_ulong(x - 1);
-}
-
-static
-void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth);
-
-static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
- unsigned long count);
-
-static long nr_cpus_mask = -1;
-static long split_count_mask = -1;
-
-#if defined(HAVE_SYSCONF)
-static void ht_init_nr_cpus_mask(void)
-{
- long maxcpus;
-
- maxcpus = sysconf(_SC_NPROCESSORS_CONF);
- if (maxcpus <= 0) {
- nr_cpus_mask = -2;
- return;
- }
- /*
- * round up number of CPUs to next power of two, so we
- * can use & for modulo.
- */
- maxcpus = 1UL << cds_lfht_get_count_order_ulong(maxcpus);
- nr_cpus_mask = maxcpus - 1;
-}
-#else /* #if defined(HAVE_SYSCONF) */
-static void ht_init_nr_cpus_mask(void)
-{
- nr_cpus_mask = -2;
-}
-#endif /* #else #if defined(HAVE_SYSCONF) */
-
-static
-void alloc_split_items_count(struct cds_lfht *ht)
-{
- struct ht_items_count *count;
-
- if (nr_cpus_mask == -1) {
- ht_init_nr_cpus_mask();
- if (nr_cpus_mask < 0)
- split_count_mask = DEFAULT_SPLIT_COUNT_MASK;
- else
- split_count_mask = nr_cpus_mask;
- }
-
- assert(split_count_mask >= 0);
-
- if (ht->flags & CDS_LFHT_ACCOUNTING) {
- ht->split_count = calloc(split_count_mask + 1, sizeof(*count));
- assert(ht->split_count);
- } else {
- ht->split_count = NULL;
- }
-}
-
-static
-void free_split_items_count(struct cds_lfht *ht)
-{
- poison_free(ht->split_count);
-}
-
-#if defined(HAVE_SCHED_GETCPU)
-static
-int ht_get_split_count_index(unsigned long hash)
-{
- int cpu;
-
- assert(split_count_mask >= 0);
- cpu = sched_getcpu();
- if (caa_unlikely(cpu < 0))
- return hash & split_count_mask;
- else
- return cpu & split_count_mask;
-}
-#else /* #if defined(HAVE_SCHED_GETCPU) */
-static
-int ht_get_split_count_index(unsigned long hash)
-{
- return hash & split_count_mask;
-}
-#endif /* #else #if defined(HAVE_SCHED_GETCPU) */
-
-static
-void ht_count_add(struct cds_lfht *ht, unsigned long size, unsigned long hash)
-{
- unsigned long split_count;
- int index;
- long count;
-
- if (caa_unlikely(!ht->split_count))
- return;
- index = ht_get_split_count_index(hash);
- split_count = uatomic_add_return(&ht->split_count[index].add, 1);
- if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))
- return;
- /* Only if number of add multiple of 1UL << COUNT_COMMIT_ORDER */
-
- dbg_printf("add split count %lu\n", split_count);
- count = uatomic_add_return(&ht->count,
- 1UL << COUNT_COMMIT_ORDER);
- if (caa_likely(count & (count - 1)))
- return;
- /* Only if global count is power of 2 */
-
- if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) < size)
- return;
- dbg_printf("add set global %ld\n", count);
- cds_lfht_resize_lazy_count(ht, size,
- count >> (CHAIN_LEN_TARGET - 1));
-}
-
-static
-void ht_count_del(struct cds_lfht *ht, unsigned long size, unsigned long hash)
-{
- unsigned long split_count;
- int index;
- long count;
-
- if (caa_unlikely(!ht->split_count))
- return;
- index = ht_get_split_count_index(hash);
- split_count = uatomic_add_return(&ht->split_count[index].del, 1);
- if (caa_likely(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))
- return;
- /* Only if number of deletes multiple of 1UL << COUNT_COMMIT_ORDER */
-
- dbg_printf("del split count %lu\n", split_count);
- count = uatomic_add_return(&ht->count,
- -(1UL << COUNT_COMMIT_ORDER));
- if (caa_likely(count & (count - 1)))
- return;
- /* Only if global count is power of 2 */
-
- if ((count >> CHAIN_LEN_RESIZE_THRESHOLD) >= size)
- return;
- dbg_printf("del set global %ld\n", count);
- /*
- * Don't shrink table if the number of nodes is below a
- * certain threshold.
- */
- if (count < (1UL << COUNT_COMMIT_ORDER) * (split_count_mask + 1))
- return;
- cds_lfht_resize_lazy_count(ht, size,
- count >> (CHAIN_LEN_TARGET - 1));
-}
-
-static
-void check_resize(struct cds_lfht *ht, unsigned long size, uint32_t chain_len)
-{
- unsigned long count;
-
- if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
- return;
- 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)
- cds_lfht_resize_lazy_grow(ht, size,
- cds_lfht_get_count_order_u32(chain_len - (CHAIN_LEN_TARGET - 1)));
-}
-
-static
-struct cds_lfht_node *clear_flag(struct cds_lfht_node *node)
-{
- return (struct cds_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK);
-}
-
-static
-int is_removed(struct cds_lfht_node *node)
-{
- return ((unsigned long) node) & REMOVED_FLAG;
-}
-
-static
-struct cds_lfht_node *flag_removed(struct cds_lfht_node *node)
-{
- return (struct cds_lfht_node *) (((unsigned long) node) | REMOVED_FLAG);
-}
-
-static
-int is_bucket(struct cds_lfht_node *node)
-{
- return ((unsigned long) node) & BUCKET_FLAG;
-}
-
-static
-struct cds_lfht_node *flag_bucket(struct cds_lfht_node *node)
-{
- return (struct cds_lfht_node *) (((unsigned long) node) | BUCKET_FLAG);
-}
-
-static
-int is_removal_owner(struct cds_lfht_node *node)
-{
- return ((unsigned long) node) & REMOVAL_OWNER_FLAG;
-}
-
-static
-struct cds_lfht_node *flag_removal_owner(struct cds_lfht_node *node)
-{
- return (struct cds_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG);
-}
-
-static
-struct cds_lfht_node *get_end(void)
-{
- return (struct cds_lfht_node *) END_VALUE;
-}
-
-static
-int is_end(struct cds_lfht_node *node)
-{
- return clear_flag(node) == (struct cds_lfht_node *) END_VALUE;
-}
-
-static
-unsigned long _uatomic_xchg_monotonic_increase(unsigned long *ptr,
- unsigned long v)
-{
- unsigned long old1, old2;
-
- old1 = uatomic_read(ptr);
- do {
- old2 = old1;
- if (old2 >= v)
- return old2;
- } while ((old1 = uatomic_cmpxchg(ptr, old2, v)) != old2);
- return old2;
-}
-
-static
-void cds_lfht_alloc_bucket_table(struct cds_lfht *ht, unsigned long order)
-{
- return ht->mm->alloc_bucket_table(ht, order);
-}
-
-/*
- * cds_lfht_free_bucket_table() should be called with decreasing order.
- * When cds_lfht_free_bucket_table(0) is called, it means the whole
- * lfht is destroyed.
- */
-static
-void cds_lfht_free_bucket_table(struct cds_lfht *ht, unsigned long order)
-{
- return ht->mm->free_bucket_table(ht, order);
-}
-
-static inline
-struct cds_lfht_node *bucket_at(struct cds_lfht *ht, unsigned long index)
-{
- return ht->bucket_at(ht, index);
-}
-
-static inline
-struct cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
- unsigned long hash)
-{
- assert(size > 0);
- return bucket_at(ht, hash & (size - 1));
-}
-
-/*
- * Remove all logically deleted nodes from a bucket up to a certain node key.
- */
-static
-void _cds_lfht_gc_bucket(struct cds_lfht_node *bucket, struct cds_lfht_node *node)
-{
- struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
-
- assert(!is_bucket(bucket));
- assert(!is_removed(bucket));
- assert(!is_bucket(node));
- assert(!is_removed(node));
- for (;;) {
- iter_prev = bucket;
- /* We can always skip the bucket node initially */
- iter = rcu_dereference(iter_prev->next);
- assert(!is_removed(iter));
- assert(iter_prev->reverse_hash <= node->reverse_hash);
- /*
- * We should never be called with bucket (start of chain)
- * and logically removed node (end of path compression
- * marker) being the actual same node. This would be a
- * bug in the algorithm implementation.
- */
- assert(bucket != node);
- for (;;) {
- if (caa_unlikely(is_end(iter)))
- return;
- if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
- return;
- next = rcu_dereference(clear_flag(iter)->next);
- if (caa_likely(is_removed(next)))
- break;
- iter_prev = clear_flag(iter);
- iter = next;
- }
- assert(!is_removed(iter));
- if (is_bucket(iter))
- new_next = flag_bucket(clear_flag(next));
- else
- new_next = clear_flag(next);
- (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
- }
-}
-
-static
-int _cds_lfht_replace(struct cds_lfht *ht, unsigned long size,
- struct cds_lfht_node *old_node,
- struct cds_lfht_node *old_next,
- struct cds_lfht_node *new_node)
-{
- struct cds_lfht_node *bucket, *ret_next;
-
- if (!old_node) /* Return -ENOENT if asked to replace NULL node */
- return -ENOENT;
-
- assert(!is_removed(old_node));
- assert(!is_bucket(old_node));
- assert(!is_removed(new_node));
- assert(!is_bucket(new_node));
- assert(new_node != old_node);
- for (;;) {
- /* Insert after node to be replaced */
- if (is_removed(old_next)) {
- /*
- * Too late, the old node has been removed under us
- * between lookup and replace. Fail.
- */
- return -ENOENT;
- }
- assert(old_next == clear_flag(old_next));
- assert(new_node != old_next);
- new_node->next = old_next;
- /*
- * Here is the whole trick for lock-free replace: we add
- * the replacement node _after_ the node we want to
- * replace by atomically setting its next pointer at the
- * same time we set its removal flag. Given that
- * the lookups/get next use an iterator aware of the
- * next pointer, they will either skip the old node due
- * to the removal flag and see the new node, or use
- * the old node, but will not see the new one.
- * This is a replacement of a node with another node
- * that has the same value: we are therefore not
- * removing a value from the hash table.
- */
- ret_next = uatomic_cmpxchg(&old_node->next,
- old_next, flag_removed(new_node));
- if (ret_next == old_next)
- break; /* We performed the replacement. */
- old_next = ret_next;
- }
-
- /*
- * Ensure that the old node is not visible to readers anymore:
- * lookup for the node, and remove it (along with any other
- * logically removed node) if found.
- */
- bucket = lookup_bucket(ht, size, bit_reverse_ulong(old_node->reverse_hash));
- _cds_lfht_gc_bucket(bucket, new_node);
-
- assert(is_removed(rcu_dereference(old_node->next)));
- return 0;
-}
-
-/*
- * A non-NULL unique_ret pointer uses the "add unique" (or uniquify) add
- * mode. A NULL unique_ret allows creation of duplicate keys.
- */
-static
-void _cds_lfht_add(struct cds_lfht *ht,
- unsigned long hash,
- cds_lfht_match_fct match,
- const void *key,
- unsigned long size,
- struct cds_lfht_node *node,
- struct cds_lfht_iter *unique_ret,
- int bucket_flag)
-{
- struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
- *return_node;
- struct cds_lfht_node *bucket;
-
- assert(!is_bucket(node));
- assert(!is_removed(node));
- bucket = lookup_bucket(ht, size, hash);
- for (;;) {
- uint32_t chain_len = 0;
-
- /*
- * iter_prev points to the non-removed node prior to the
- * insert location.
- */
- iter_prev = bucket;
- /* We can always skip the bucket node initially */
- iter = rcu_dereference(iter_prev->next);
- assert(iter_prev->reverse_hash <= node->reverse_hash);
- for (;;) {
- if (caa_unlikely(is_end(iter)))
- goto insert;
- if (caa_likely(clear_flag(iter)->reverse_hash > node->reverse_hash))
- goto insert;
-
- /* bucket node is the first node of the identical-hash-value chain */
- if (bucket_flag && clear_flag(iter)->reverse_hash == node->reverse_hash)
- goto insert;
-
- next = rcu_dereference(clear_flag(iter)->next);
- if (caa_unlikely(is_removed(next)))
- goto gc_node;
-
- /* uniquely add */
- if (unique_ret
- && !is_bucket(next)
- && clear_flag(iter)->reverse_hash == node->reverse_hash) {
- struct cds_lfht_iter d_iter = { .node = node, .next = iter, };
-
- /*
- * uniquely adding inserts the node as the first
- * node of the identical-hash-value node chain.
- *
- * This semantic ensures no duplicated keys
- * should ever be observable in the table
- * (including observe one node by one node
- * by forward iterations)
- */
- cds_lfht_next_duplicate(ht, match, key, &d_iter);
- if (!d_iter.node)
- goto insert;
-
- *unique_ret = d_iter;
- return;
- }
-
- /* Only account for identical reverse hash once */
- if (iter_prev->reverse_hash != clear_flag(iter)->reverse_hash
- && !is_bucket(next))
- check_resize(ht, size, ++chain_len);
- iter_prev = clear_flag(iter);
- iter = next;
- }
-
- insert:
- assert(node != clear_flag(iter));
- assert(!is_removed(iter_prev));
- assert(!is_removed(iter));
- assert(iter_prev != node);
- if (!bucket_flag)
- node->next = clear_flag(iter);
- else
- node->next = flag_bucket(clear_flag(iter));
- if (is_bucket(iter))
- new_node = flag_bucket(node);
- else
- new_node = node;
- if (uatomic_cmpxchg(&iter_prev->next, iter,
- new_node) != iter) {
- continue; /* retry */
- } else {
- return_node = node;
- goto end;
- }
-
- gc_node:
- assert(!is_removed(iter));
- if (is_bucket(iter))
- new_next = flag_bucket(clear_flag(next));
- else
- new_next = clear_flag(next);
- (void) uatomic_cmpxchg(&iter_prev->next, iter, new_next);
- /* retry */
- }
-end:
- if (unique_ret) {
- unique_ret->node = return_node;
- /* unique_ret->next left unset, never used. */
- }
-}
-
-static
-int _cds_lfht_del(struct cds_lfht *ht, unsigned long size,
- struct cds_lfht_node *node)
-{
- struct cds_lfht_node *bucket, *next;
-
- if (!node) /* Return -ENOENT if asked to delete NULL node */
- return -ENOENT;
-
- /* logically delete the node */
- assert(!is_bucket(node));
- assert(!is_removed(node));
- assert(!is_removal_owner(node));
-
- /*
- * We are first checking if the node had previously been
- * logically removed (this check is not atomic with setting the
- * logical removal flag). Return -ENOENT if the node had
- * previously been removed.
- */
- next = rcu_dereference(node->next);
- if (caa_unlikely(is_removed(next)))
- return -ENOENT;
- assert(!is_bucket(next));
- /*
- * We set the REMOVED_FLAG unconditionally. Note that there may
- * be more than one concurrent thread setting this flag.
- * Knowing which wins the race will be known after the garbage
- * collection phase, stay tuned!
- */
- uatomic_or(&node->next, REMOVED_FLAG);
- /* We performed the (logical) deletion. */
-
- /*
- * Ensure that the node is not visible to readers anymore: lookup for
- * the node, and remove it (along with any other logically removed node)
- * if found.
- */
- bucket = lookup_bucket(ht, size, bit_reverse_ulong(node->reverse_hash));
- _cds_lfht_gc_bucket(bucket, node);
-
- assert(is_removed(rcu_dereference(node->next)));
- /*
- * Last phase: atomically exchange node->next with a version
- * having "REMOVAL_OWNER_FLAG" set. If the returned node->next
- * pointer did _not_ have "REMOVAL_OWNER_FLAG" set, we now own
- * the node and win the removal race.
- * It is interesting to note that all "add" paths are forbidden
- * to change the next pointer starting from the point where the
- * REMOVED_FLAG is set, so here using a read, followed by a
- * xchg() suffice to guarantee that the xchg() will ever only
- * set the "REMOVAL_OWNER_FLAG" (or change nothing if the flag
- * was already set).
- */
- if (!is_removal_owner(uatomic_xchg(&node->next,
- flag_removal_owner(node->next))))
- return 0;
- else
- return -ENOENT;
-}
-
-static
-void *partition_resize_thread(void *arg)
-{
- struct partition_resize_work *work = arg;
-
- work->ht->flavor->register_thread();
- work->fct(work->ht, work->i, work->start, work->len);
- work->ht->flavor->unregister_thread();
- return NULL;
-}
-
-static
-void partition_resize_helper(struct cds_lfht *ht, unsigned long i,
- unsigned long len,
- void (*fct)(struct cds_lfht *ht, unsigned long i,
- unsigned long start, unsigned long len))
-{
- unsigned long partition_len;
- struct partition_resize_work *work;
- int thread, ret;
- unsigned long nr_threads;
-
- /*
- * Note: nr_cpus_mask + 1 is always power of 2.
- * We spawn just the number of threads we need to satisfy the minimum
- * partition size, up to the number of CPUs in the system.
- */
- if (nr_cpus_mask > 0) {
- nr_threads = min(nr_cpus_mask + 1,
- len >> MIN_PARTITION_PER_THREAD_ORDER);
- } else {
- nr_threads = 1;
- }
- partition_len = len >> cds_lfht_get_count_order_ulong(nr_threads);
- work = calloc(nr_threads, sizeof(*work));
- assert(work);
- for (thread = 0; thread < nr_threads; thread++) {
- work[thread].ht = ht;
- work[thread].i = i;
- work[thread].len = partition_len;
- work[thread].start = thread * partition_len;
- work[thread].fct = fct;
- ret = pthread_create(&(work[thread].thread_id), ht->resize_attr,
- partition_resize_thread, &work[thread]);
- assert(!ret);
- }
- for (thread = 0; thread < nr_threads; thread++) {
- ret = pthread_join(work[thread].thread_id, NULL);
- assert(!ret);
- }
- free(work);
-}
-
-/*
- * Holding RCU read lock to protect _cds_lfht_add against memory
- * reclaim that could be performed by other call_rcu worker threads (ABA
- * problem).
- *
- * When we reach a certain length, we can split this population phase over
- * many worker threads, based on the number of CPUs available in the system.
- * This should therefore take care of not having the expand lagging behind too
- * many concurrent insertion threads by using the scheduler's ability to
- * schedule bucket node population fairly with insertions.
- */
-static
-void init_table_populate_partition(struct cds_lfht *ht, unsigned long i,
- unsigned long start, unsigned long len)
-{
- unsigned long j, size = 1UL << (i - 1);
-
- assert(i > MIN_TABLE_ORDER);
- ht->flavor->read_lock();
- for (j = size + start; j < size + start + len; j++) {
- struct cds_lfht_node *new_node = bucket_at(ht, j);
-
- assert(j >= size && j < (size << 1));
- dbg_printf("init populate: order %lu index %lu hash %lu\n",
- i, j, j);
- new_node->reverse_hash = bit_reverse_ulong(j);
- _cds_lfht_add(ht, j, NULL, NULL, size, new_node, NULL, 1);
- }
- ht->flavor->read_unlock();
-}
-
-static
-void init_table_populate(struct cds_lfht *ht, unsigned long i,
- unsigned long len)
-{
- assert(nr_cpus_mask != -1);
- if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
- ht->flavor->thread_online();
- init_table_populate_partition(ht, i, 0, len);
- ht->flavor->thread_offline();
- return;
- }
- partition_resize_helper(ht, i, len, init_table_populate_partition);
-}
-
-static
-void init_table(struct cds_lfht *ht,
- unsigned long first_order, unsigned long last_order)
-{
- unsigned long i;
-
- dbg_printf("init table: first_order %lu last_order %lu\n",
- first_order, last_order);
- assert(first_order > MIN_TABLE_ORDER);
- for (i = first_order; i <= last_order; i++) {
- unsigned long len;
-
- len = 1UL << (i - 1);
- dbg_printf("init order %lu len: %lu\n", i, len);
-
- /* Stop expand if the resize target changes under us */
- if (CMM_LOAD_SHARED(ht->resize_target) < (1UL << i))
- break;
-
- cds_lfht_alloc_bucket_table(ht, i);
-
- /*
- * Set all bucket nodes reverse hash values for a level and
- * link all bucket nodes into the table.
- */
- init_table_populate(ht, i, len);
-
- /*
- * Update table size.
- */
- cmm_smp_wmb(); /* populate data before RCU size */
- CMM_STORE_SHARED(ht->size, 1UL << i);
-
- dbg_printf("init new size: %lu\n", 1UL << i);
- if (CMM_LOAD_SHARED(ht->in_progress_destroy))
- break;
- }
-}
-
-/*
- * 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 bucket 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.
- *
- * When we reach a certain length, we can split this removal over many worker
- * threads, based on the number of CPUs available in the system. This should
- * take care of not letting resize process lag behind too many concurrent
- * updater threads actively inserting into the hash table.
- */
-static
-void remove_table_partition(struct cds_lfht *ht, unsigned long i,
- unsigned long start, unsigned long len)
-{
- unsigned long j, size = 1UL << (i - 1);
-
- assert(i > MIN_TABLE_ORDER);
- ht->flavor->read_lock();
- for (j = size + start; j < size + start + len; j++) {
- struct cds_lfht_node *fini_bucket = bucket_at(ht, j);
- struct cds_lfht_node *parent_bucket = bucket_at(ht, j - size);
-
- assert(j >= size && j < (size << 1));
- dbg_printf("remove entry: order %lu index %lu hash %lu\n",
- i, j, j);
- /* Set the REMOVED_FLAG to freeze the ->next for gc */
- uatomic_or(&fini_bucket->next, REMOVED_FLAG);
- _cds_lfht_gc_bucket(parent_bucket, fini_bucket);
- }
- ht->flavor->read_unlock();
-}
-
-static
-void remove_table(struct cds_lfht *ht, unsigned long i, unsigned long len)
-{
-
- assert(nr_cpus_mask != -1);
- if (nr_cpus_mask < 0 || len < 2 * MIN_PARTITION_PER_THREAD) {
- ht->flavor->thread_online();
- remove_table_partition(ht, i, 0, len);
- ht->flavor->thread_offline();
- return;
- }
- partition_resize_helper(ht, i, len, remove_table_partition);
-}
-
-/*
- * fini_table() is never called for first_order == 0, which is why
- * free_by_rcu_order == 0 can be used as criterion to know if free must
- * be called.
- */
-static
-void fini_table(struct cds_lfht *ht,
- unsigned long first_order, unsigned long last_order)
-{
- long i;
- unsigned long free_by_rcu_order = 0;
-
- dbg_printf("fini table: first_order %lu last_order %lu\n",
- first_order, last_order);
- assert(first_order > MIN_TABLE_ORDER);
- for (i = last_order; i >= first_order; i--) {
- unsigned long len;
-
- len = 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->resize_target) > (1UL << (i - 1)))
- break;
-
- cmm_smp_wmb(); /* populate data before RCU size */
- CMM_STORE_SHARED(ht->size, 1UL << (i - 1));
-
- /*
- * 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 bucket nodes. Otherwise their lookup will
- * return a logically removed node as insert position.
- */
- ht->flavor->update_synchronize_rcu();
- if (free_by_rcu_order)
- cds_lfht_free_bucket_table(ht, free_by_rcu_order);
-
- /*
- * Set "removed" flag in bucket nodes about to be removed.
- * Unlink all now-logically-removed bucket node pointers.
- * Concurrent add/remove operation are helping us doing
- * the gc.
- */
- remove_table(ht, i, len);
-
- free_by_rcu_order = i;
-
- dbg_printf("fini new size: %lu\n", 1UL << i);
- if (CMM_LOAD_SHARED(ht->in_progress_destroy))
- break;
- }
-
- if (free_by_rcu_order) {
- ht->flavor->update_synchronize_rcu();
- cds_lfht_free_bucket_table(ht, free_by_rcu_order);
- }
-}
-
-static
-void cds_lfht_create_bucket(struct cds_lfht *ht, unsigned long size)
-{
- struct cds_lfht_node *prev, *node;
- unsigned long order, len, i;
-
- cds_lfht_alloc_bucket_table(ht, 0);
-
- dbg_printf("create bucket: order 0 index 0 hash 0\n");
- node = bucket_at(ht, 0);
- node->next = flag_bucket(get_end());
- node->reverse_hash = 0;
-
- for (order = 1; order < cds_lfht_get_count_order_ulong(size) + 1; order++) {
- len = 1UL << (order - 1);
- cds_lfht_alloc_bucket_table(ht, order);
-
- for (i = 0; i < len; i++) {
- /*
- * Now, we are trying to init the node with the
- * hash=(len+i) (which is also a bucket with the
- * index=(len+i)) and insert it into the hash table,
- * so this node has to be inserted after the bucket
- * with the index=(len+i)&(len-1)=i. And because there
- * is no other non-bucket node nor bucket node with
- * larger index/hash inserted, so the bucket node
- * being inserted should be inserted directly linked
- * after the bucket node with index=i.
- */
- prev = bucket_at(ht, i);
- node = bucket_at(ht, len + i);
-
- dbg_printf("create bucket: order %lu index %lu hash %lu\n",
- order, len + i, len + i);
- node->reverse_hash = bit_reverse_ulong(len + i);
-
- /* insert after prev */
- assert(is_bucket(prev->next));
- node->next = prev->next;
- prev->next = flag_bucket(node);
- }
- }
-}
-
-struct cds_lfht *_cds_lfht_new(unsigned long init_size,
- unsigned long min_nr_alloc_buckets,
- unsigned long max_nr_buckets,
- int flags,
- const struct cds_lfht_mm_type *mm,
- const struct rcu_flavor_struct *flavor,
- pthread_attr_t *attr)
-{
- struct cds_lfht *ht;
- unsigned long order;
-
- /* min_nr_alloc_buckets must be power of two */
- if (!min_nr_alloc_buckets || (min_nr_alloc_buckets & (min_nr_alloc_buckets - 1)))
- return NULL;
-
- /* init_size must be power of two */
- if (!init_size || (init_size & (init_size - 1)))
- return NULL;
-
- /*
- * Memory management plugin default.
- */
- if (!mm) {
- if (CAA_BITS_PER_LONG > 32
- && max_nr_buckets
- && max_nr_buckets <= (1ULL << 32)) {
- /*
- * For 64-bit architectures, with max number of
- * buckets small enough not to use the entire
- * 64-bit memory mapping space (and allowing a
- * fair number of hash table instances), use the
- * mmap allocator, which is faster than the
- * order allocator.
- */
- mm = &cds_lfht_mm_mmap;
- } else {
- /*
- * The fallback is to use the order allocator.
- */
- mm = &cds_lfht_mm_order;
- }
- }
-
- /* max_nr_buckets == 0 for order based mm means infinite */
- if (mm == &cds_lfht_mm_order && !max_nr_buckets)
- max_nr_buckets = 1UL << (MAX_TABLE_ORDER - 1);
-
- /* max_nr_buckets must be power of two */
- if (!max_nr_buckets || (max_nr_buckets & (max_nr_buckets - 1)))
- return NULL;
-
- min_nr_alloc_buckets = max(min_nr_alloc_buckets, MIN_TABLE_SIZE);
- init_size = max(init_size, MIN_TABLE_SIZE);
- max_nr_buckets = max(max_nr_buckets, min_nr_alloc_buckets);
- init_size = min(init_size, max_nr_buckets);
-
- ht = mm->alloc_cds_lfht(min_nr_alloc_buckets, max_nr_buckets);
- assert(ht);
- assert(ht->mm == mm);
- assert(ht->bucket_at == mm->bucket_at);
-
- ht->flags = flags;
- ht->flavor = flavor;
- ht->resize_attr = attr;
- alloc_split_items_count(ht);
- /* this mutex should not nest in read-side C.S. */
- pthread_mutex_init(&ht->resize_mutex, NULL);
- order = cds_lfht_get_count_order_ulong(init_size);
- ht->resize_target = 1UL << order;
- cds_lfht_create_bucket(ht, 1UL << order);
- ht->size = 1UL << order;
- return ht;
-}
-
-void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
- cds_lfht_match_fct match, const void *key,
- struct cds_lfht_iter *iter)
-{
- struct cds_lfht_node *node, *next, *bucket;
- unsigned long reverse_hash, size;
-
- reverse_hash = bit_reverse_ulong(hash);
-
- size = rcu_dereference(ht->size);
- bucket = lookup_bucket(ht, size, hash);
- /* We can always skip the bucket node initially */
- node = rcu_dereference(bucket->next);
- node = clear_flag(node);
- for (;;) {
- if (caa_unlikely(is_end(node))) {
- node = next = NULL;
- break;
- }
- if (caa_unlikely(node->reverse_hash > reverse_hash)) {
- node = next = NULL;
- break;
- }
- next = rcu_dereference(node->next);
- assert(node == clear_flag(node));
- if (caa_likely(!is_removed(next))
- && !is_bucket(next)
- && node->reverse_hash == reverse_hash
- && caa_likely(match(node, key))) {
- break;
- }
- node = clear_flag(next);
- }
- assert(!node || !is_bucket(rcu_dereference(node->next)));
- iter->node = node;
- iter->next = next;
-}
-
-void cds_lfht_next_duplicate(struct cds_lfht *ht, cds_lfht_match_fct match,
- const void *key, struct cds_lfht_iter *iter)
-{
- struct cds_lfht_node *node, *next;
- unsigned long reverse_hash;
-
- node = iter->node;
- reverse_hash = node->reverse_hash;
- next = iter->next;
- node = clear_flag(next);
-
- for (;;) {
- if (caa_unlikely(is_end(node))) {
- node = next = NULL;
- break;
- }
- if (caa_unlikely(node->reverse_hash > reverse_hash)) {
- node = next = NULL;
- break;
- }
- next = rcu_dereference(node->next);
- if (caa_likely(!is_removed(next))
- && !is_bucket(next)
- && caa_likely(match(node, key))) {
- break;
- }
- node = clear_flag(next);
- }
- assert(!node || !is_bucket(rcu_dereference(node->next)));
- iter->node = node;
- iter->next = next;
-}
-
-void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter)
-{
- struct cds_lfht_node *node, *next;
-
- node = clear_flag(iter->next);
- for (;;) {
- if (caa_unlikely(is_end(node))) {
- node = next = NULL;
- break;
- }
- next = rcu_dereference(node->next);
- if (caa_likely(!is_removed(next))
- && !is_bucket(next)) {
- break;
- }
- node = clear_flag(next);
- }
- assert(!node || !is_bucket(rcu_dereference(node->next)));
- iter->node = node;
- iter->next = next;
-}
-
-void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
-{
- /*
- * Get next after first bucket node. The first bucket node is the
- * first node of the linked list.
- */
- iter->next = bucket_at(ht, 0)->next;
- cds_lfht_next(ht, iter);
-}
-
-void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
- struct cds_lfht_node *node)
-{
- unsigned long size;
-
- node->reverse_hash = bit_reverse_ulong(hash);
- size = rcu_dereference(ht->size);
- _cds_lfht_add(ht, hash, NULL, NULL, size, node, NULL, 0);
- ht_count_add(ht, size, hash);
-}
-
-struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
- unsigned long hash,
- cds_lfht_match_fct match,
- const void *key,
- struct cds_lfht_node *node)
-{
- unsigned long size;
- struct cds_lfht_iter iter;
-
- node->reverse_hash = bit_reverse_ulong(hash);
- size = rcu_dereference(ht->size);
- _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0);
- if (iter.node == node)
- ht_count_add(ht, size, hash);
- return iter.node;
-}
-
-struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
- unsigned long hash,
- cds_lfht_match_fct match,
- const void *key,
- struct cds_lfht_node *node)
-{
- unsigned long size;
- struct cds_lfht_iter iter;
-
- node->reverse_hash = bit_reverse_ulong(hash);
- size = rcu_dereference(ht->size);
- for (;;) {
- _cds_lfht_add(ht, hash, match, key, size, node, &iter, 0);
- if (iter.node == node) {
- ht_count_add(ht, size, hash);
- return NULL;
- }
-
- if (!_cds_lfht_replace(ht, size, iter.node, iter.next, node))
- return iter.node;
- }
-}
-
-int cds_lfht_replace(struct cds_lfht *ht,
- struct cds_lfht_iter *old_iter,
- unsigned long hash,
- cds_lfht_match_fct match,
- const void *key,
- struct cds_lfht_node *new_node)
-{
- unsigned long size;
-
- new_node->reverse_hash = bit_reverse_ulong(hash);
- if (!old_iter->node)
- return -ENOENT;
- if (caa_unlikely(old_iter->node->reverse_hash != new_node->reverse_hash))
- return -EINVAL;
- if (caa_unlikely(!match(old_iter->node, key)))
- return -EINVAL;
- size = rcu_dereference(ht->size);
- return _cds_lfht_replace(ht, size, old_iter->node, old_iter->next,
- new_node);
-}
-
-int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node)
-{
- unsigned long size, hash;
- int ret;
-
- size = rcu_dereference(ht->size);
- ret = _cds_lfht_del(ht, size, node);
- if (!ret) {
- hash = bit_reverse_ulong(node->reverse_hash);
- ht_count_del(ht, size, hash);
- }
- return ret;
-}
-
-static
-int cds_lfht_delete_bucket(struct cds_lfht *ht)
-{
- struct cds_lfht_node *node;
- unsigned long order, i, size;
-
- /* Check that the table is empty */
- node = bucket_at(ht, 0);
- do {
- node = clear_flag(node)->next;
- if (!is_bucket(node))
- return -EPERM;
- assert(!is_removed(node));
- } while (!is_end(node));
- /*
- * size accessed without rcu_dereference because hash table is
- * being destroyed.
- */
- size = ht->size;
- /* Internal sanity check: all nodes left should be bucket */
- for (i = 0; i < size; i++) {
- node = bucket_at(ht, i);
- dbg_printf("delete bucket: index %lu expected hash %lu hash %lu\n",
- i, i, bit_reverse_ulong(node->reverse_hash));
- assert(is_bucket(node->next));
- }
-
- for (order = cds_lfht_get_count_order_ulong(size); (long)order >= 0; order--)
- cds_lfht_free_bucket_table(ht, order);
-
- return 0;
-}
-
-/*
- * Should only be called when no more concurrent readers nor writers can
- * possibly access the table.
- */
-int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr)
-{
- int ret;
-
- /* Wait for in-flight resize operations to complete */
- _CMM_STORE_SHARED(ht->in_progress_destroy, 1);
- cmm_smp_mb(); /* Store destroy before load resize */
- while (uatomic_read(&ht->in_progress_resize))
- poll(NULL, 0, 100); /* wait for 100ms */
- ret = cds_lfht_delete_bucket(ht);
- if (ret)
- return ret;
- free_split_items_count(ht);
- if (attr)
- *attr = ht->resize_attr;
- poison_free(ht);
- return ret;
-}
-
-void cds_lfht_count_nodes(struct cds_lfht *ht,
- long *approx_before,
- unsigned long *count,
- long *approx_after)
-{
- struct cds_lfht_node *node, *next;
- unsigned long nr_bucket = 0, nr_removed = 0;
-
- *approx_before = 0;
- if (ht->split_count) {
- int i;
-
- for (i = 0; i < split_count_mask + 1; i++) {
- *approx_before += uatomic_read(&ht->split_count[i].add);
- *approx_before -= uatomic_read(&ht->split_count[i].del);
- }
- }
-
- *count = 0;
-
- /* Count non-bucket nodes in the table */
- node = bucket_at(ht, 0);
- do {
- next = rcu_dereference(node->next);
- if (is_removed(next)) {
- if (!is_bucket(next))
- (nr_removed)++;
- else
- (nr_bucket)++;
- } else if (!is_bucket(next))
- (*count)++;
- else
- (nr_bucket)++;
- node = clear_flag(next);
- } while (!is_end(node));
- dbg_printf("number of logically removed nodes: %lu\n", nr_removed);
- dbg_printf("number of bucket nodes: %lu\n", nr_bucket);
- *approx_after = 0;
- if (ht->split_count) {
- int i;
-
- for (i = 0; i < split_count_mask + 1; i++) {
- *approx_after += uatomic_read(&ht->split_count[i].add);
- *approx_after -= uatomic_read(&ht->split_count[i].del);
- }
- }
-}
-
-/* called with resize mutex held */
-static
-void _do_cds_lfht_grow(struct cds_lfht *ht,
- unsigned long old_size, unsigned long new_size)
-{
- unsigned long old_order, new_order;
-
- old_order = cds_lfht_get_count_order_ulong(old_size);
- new_order = cds_lfht_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 + 1, new_order);
-}
-
-/* called with resize mutex held */
-static
-void _do_cds_lfht_shrink(struct cds_lfht *ht,
- unsigned long old_size, unsigned long new_size)
-{
- unsigned long old_order, new_order;
-
- new_size = max(new_size, MIN_TABLE_SIZE);
- old_order = cds_lfht_get_count_order_ulong(old_size);
- new_order = cds_lfht_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 bucket nodes to remove. */
- fini_table(ht, new_order + 1, old_order);
-}
-
-
-/* called with resize mutex held */
-static
-void _do_cds_lfht_resize(struct cds_lfht *ht)
-{
- unsigned long new_size, old_size;
-
- /*
- * Resize table, re-do if the target size has changed under us.
- */
- do {
- assert(uatomic_read(&ht->in_progress_resize));
- if (CMM_LOAD_SHARED(ht->in_progress_destroy))
- break;
- ht->resize_initiated = 1;
- old_size = ht->size;
- new_size = CMM_LOAD_SHARED(ht->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->resize_initiated = 0;
- /* write resize_initiated before read resize_target */
- cmm_smp_mb();
- } while (ht->size != CMM_LOAD_SHARED(ht->resize_target));
-}
-
-static
-unsigned long resize_target_grow(struct cds_lfht *ht, unsigned long new_size)
-{
- return _uatomic_xchg_monotonic_increase(&ht->resize_target, new_size);
-}
-
-static
-void resize_target_update_count(struct cds_lfht *ht,
- unsigned long count)
-{
- count = max(count, MIN_TABLE_SIZE);
- count = min(count, ht->max_nr_buckets);
- uatomic_set(&ht->resize_target, count);
-}
-
-void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size)
-{
- resize_target_update_count(ht, new_size);
- CMM_STORE_SHARED(ht->resize_initiated, 1);
- ht->flavor->thread_offline();
- pthread_mutex_lock(&ht->resize_mutex);
- _do_cds_lfht_resize(ht);
- pthread_mutex_unlock(&ht->resize_mutex);
- ht->flavor->thread_online();
-}
-
-static
-void do_resize_cb(struct rcu_head *head)
-{
- struct rcu_resize_work *work =
- caa_container_of(head, struct rcu_resize_work, head);
- struct cds_lfht *ht = work->ht;
-
- ht->flavor->thread_offline();
- pthread_mutex_lock(&ht->resize_mutex);
- _do_cds_lfht_resize(ht);
- pthread_mutex_unlock(&ht->resize_mutex);
- ht->flavor->thread_online();
- poison_free(work);
- cmm_smp_mb(); /* finish resize before decrement */
- uatomic_dec(&ht->in_progress_resize);
-}
-
-static
-void __cds_lfht_resize_lazy_launch(struct cds_lfht *ht)
-{
- struct rcu_resize_work *work;
-
- /* Store resize_target before read resize_initiated */
- cmm_smp_mb();
- if (!CMM_LOAD_SHARED(ht->resize_initiated)) {
- uatomic_inc(&ht->in_progress_resize);
- cmm_smp_mb(); /* increment resize count before load destroy */
- if (CMM_LOAD_SHARED(ht->in_progress_destroy)) {
- uatomic_dec(&ht->in_progress_resize);
- return;
- }
- work = malloc(sizeof(*work));
- work->ht = ht;
- ht->flavor->update_call_rcu(&work->head, do_resize_cb);
- CMM_STORE_SHARED(ht->resize_initiated, 1);
- }
-}
-
-static
-void cds_lfht_resize_lazy_grow(struct cds_lfht *ht, unsigned long size, int growth)
-{
- unsigned long target_size = size << growth;
-
- target_size = min(target_size, ht->max_nr_buckets);
- if (resize_target_grow(ht, target_size) >= target_size)
- return;
-
- __cds_lfht_resize_lazy_launch(ht);
-}
-
-/*
- * We favor grow operations over shrink. A shrink operation never occurs
- * if a grow operation is queued for lazy execution. A grow operation
- * cancels any pending shrink lazy execution.
- */
-static
-void cds_lfht_resize_lazy_count(struct cds_lfht *ht, unsigned long size,
- unsigned long count)
-{
- if (!(ht->flags & CDS_LFHT_AUTO_RESIZE))
- return;
- count = max(count, MIN_TABLE_SIZE);
- count = min(count, ht->max_nr_buckets);
- if (count == size)
- return; /* Already the right size, no resize needed */
- if (count > size) { /* lazy grow */
- if (resize_target_grow(ht, count) >= count)
- return;
- } else { /* lazy shrink */
- for (;;) {
- unsigned long s;
-
- s = uatomic_cmpxchg(&ht->resize_target, size, count);
- if (s == size)
- break; /* no resize needed */
- if (s > size)
- return; /* growing is/(was just) in progress */
- if (s <= count)
- return; /* some other thread do shrink */
- size = s;
- }
- }
- __cds_lfht_resize_lazy_launch(ht);
-}
projects / lttng-tools.git / blobdiff