--- /dev/null
+/*
+ * rculfhash.c
+ *
+ * Userspace RCU library - Lock-Free Resizable RCU Hash Table
+ *
+ * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.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 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 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 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 (except for order 0).
+ * - synchronzie_rcu is used to garbage-collect the old dummy node table.
+ * - The per-order dummy node tables contain a compact version of the
+ * hash table nodes. These tables are invariant after they are
+ * populated into the hash table.
+ *
+ * Dummy node tables:
+ *
+ * hash table hash table the last all dummy node tables
+ * order size dummy node 0 1 2 3 4 5 6(index)
+ * table size
+ * 0 1 1 1
+ * 1 2 1 1 1
+ * 2 4 2 1 1 2
+ * 3 8 4 1 1 2 4
+ * 4 16 8 1 1 2 4 8
+ * 5 32 16 1 1 2 4 8 16
+ * 6 64 32 1 1 2 4 8 16 32
+ *
+ * When growing/shrinking, we only focus on the last dummy node table
+ * which size is (!order ? 1 : (1 << (order -1))).
+ *
+ * Example for growing/shrinking:
+ * grow hash table from order 5 to 6: init the index=6 dummy node table
+ * shrink hash table from order 6 to 5: fini the index=6 dummy node table
+ *
+ * A bit of ascii art explanation:
+ *
+ * Order index is the off-by-one compare to the actual power of 2 because
+ * 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"
+
+#ifdef DEBUG
+#define dbg_printf(fmt, args...) printf("[debug rculfhash] " fmt, ## args)
+#else
+#define dbg_printf(fmt, args...)
+#endif
+
+/*
+ * 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_SIZE 1
+
+#if (CAA_BITS_PER_LONG == 32)
+#define MAX_TABLE_ORDER 32
+#else
+#define MAX_TABLE_ORDER 64
+#endif
+
+/*
+ * Minimum number of dummy 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)
+
+#ifndef min
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef max
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
+/*
+ * 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 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)
+
+/* Value of the end pointer. Should not interact with flags. */
+#define END_VALUE NULL
+
+/*
+ * 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_level: Contains the per order-index-level dummy node table. The
+ * size of each dummy node table is half the number of hashes contained
+ * in this order (except for order 0). The minimum allocation size
+ * parameter allows combining the dummy node arrays of the lowermost
+ * levels to improve cache locality for small index orders.
+ */
+struct rcu_level {
+ /* Note: manually update allocation length when adding a field */
+ struct _cds_lfht_node nodes[0];
+};
+
+/*
+ * rcu_table: Contains the size and desired new size if a resize
+ * operation is in progress, as well as the statically-sized array of
+ * rcu_level pointers.
+ */
+struct rcu_table {
+ unsigned long size; /* always a power of 2, shared (RCU) */
+ unsigned long resize_target;
+ int resize_initiated;
+ struct rcu_level *tbl[MAX_TABLE_ORDER];
+};
+
+/*
+ * cds_lfht: Top-level data structure representing a lock-free hash
+ * table. Defined in the implementation file to make it be an opaque
+ * cookie to users.
+ */
+struct cds_lfht {
+ struct rcu_table t;
+ cds_lfht_hash_fct hash_fct;
+ cds_lfht_compare_fct compare_fct;
+ unsigned long min_alloc_order;
+ unsigned long min_alloc_size;
+ 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 (*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_thread_offline)(void);
+ void (*cds_lfht_rcu_thread_online)(void);
+ void (*cds_lfht_rcu_register_thread)(void);
+ void (*cds_lfht_rcu_unregister_thread)(void);
+ pthread_attr_t *resize_attr; /* Resize threads attributes */
+ long count; /* global approximate item count */
+ struct ht_items_count *split_count; /* split item count */
+};
+
+/*
+ * 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);
+};
+
+static
+void _cds_lfht_add(struct cds_lfht *ht,
+ unsigned long size,
+ struct cds_lfht_node *node,
+ struct cds_lfht_iter *unique_ret,
+ int dummy);
+
+/*
+ * 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 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 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 get_count_order_ulong(unsigned long x)
+{
+ if (!x)
+ return -1;
+
+ return fls_ulong(x - 1);
+}
+
+#ifdef POISON_FREE
+#define poison_free(ptr) \
+ do { \
+ if (ptr) { \
+ memset(ptr, 0x42, sizeof(*(ptr))); \
+ free(ptr); \
+ } \
+ } while (0)
+#else
+#define poison_free(ptr) free(ptr)
+#endif
+
+static
+void cds_lfht_resize_lazy(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 << 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;
+
+ 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_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+ long count;
+
+ dbg_printf("add split count %lu\n", split_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) < 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;
+
+ 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_unlikely(!(split_count & ((1UL << COUNT_COMMIT_ORDER) - 1)))) {
+ long count;
+
+ dbg_printf("del split count %lu\n", split_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) >= 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(ht, size,
+ 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_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
+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_max(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 v;
+}
+
+static
+struct _cds_lfht_node *lookup_bucket(struct cds_lfht *ht, unsigned long size,
+ unsigned long hash)
+{
+ unsigned long index, order;
+
+ assert(size > 0);
+ index = hash & (size - 1);
+
+ if (index < ht->min_alloc_size) {
+ dbg_printf("lookup hash %lu index %lu order 0 aridx 0\n",
+ hash, index);
+ return &ht->t.tbl[0]->nodes[index];
+ }
+ /*
+ * equivalent to get_count_order_ulong(index + 1), but optimizes
+ * away the non-existing 0 special-case for
+ * get_count_order_ulong.
+ */
+ order = fls_ulong(index);
+ dbg_printf("lookup hash %lu index %lu order %lu aridx %lu\n",
+ hash, index, order, index & ((1UL << (order - 1)) - 1));
+ return &ht->t.tbl[order]->nodes[index & ((1UL << (order - 1)) - 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 *dummy, struct cds_lfht_node *node)
+{
+ struct cds_lfht_node *iter_prev, *iter, *next, *new_next;
+
+ assert(!is_dummy(dummy));
+ assert(!is_removed(dummy));
+ assert(!is_dummy(node));
+ assert(!is_removed(node));
+ for (;;) {
+ iter_prev = dummy;
+ /* We can always skip the dummy node initially */
+ iter = rcu_dereference(iter_prev->p.next);
+ assert(!is_removed(iter));
+ assert(iter_prev->p.reverse_hash <= node->p.reverse_hash);
+ /*
+ * We should never be called with dummy (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(dummy != node);
+ for (;;) {
+ if (caa_unlikely(is_end(iter)))
+ return;
+ if (caa_likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+ return;
+ next = rcu_dereference(clear_flag(iter)->p.next);
+ if (caa_likely(is_removed(next)))
+ break;
+ iter_prev = clear_flag(iter);
+ iter = next;
+ }
+ assert(!is_removed(iter));
+ 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);
+ }
+ return;
+}
+
+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 *dummy, *ret_next;
+ struct _cds_lfht_node *lookup;
+
+ if (!old_node) /* Return -ENOENT if asked to replace NULL node */
+ return -ENOENT;
+
+ assert(!is_removed(old_node));
+ assert(!is_dummy(old_node));
+ assert(!is_removed(new_node));
+ assert(!is_dummy(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(!is_dummy(old_next));
+ assert(new_node != clear_flag(old_next));
+ new_node->p.next = clear_flag(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.
+ */
+ ret_next = uatomic_cmpxchg(&old_node->p.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.
+ */
+ lookup = lookup_bucket(ht, size, bit_reverse_ulong(old_node->p.reverse_hash));
+ dummy = (struct cds_lfht_node *) lookup;
+ _cds_lfht_gc_bucket(dummy, new_node);
+
+ assert(is_removed(rcu_dereference(old_node->p.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 size,
+ struct cds_lfht_node *node,
+ struct cds_lfht_iter *unique_ret,
+ int dummy)
+{
+ struct cds_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
+ *return_node;
+ struct _cds_lfht_node *lookup;
+
+ assert(!is_dummy(node));
+ assert(!is_removed(node));
+ lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash));
+ for (;;) {
+ uint32_t chain_len = 0;
+
+ /*
+ * iter_prev points to the non-removed node prior to the
+ * insert location.
+ */
+ 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 (caa_unlikely(is_end(iter)))
+ goto insert;
+ if (caa_likely(clear_flag(iter)->p.reverse_hash > node->p.reverse_hash))
+ goto insert;
+
+ /* dummy node is the first node of the identical-hash-value chain */
+ if (dummy && clear_flag(iter)->p.reverse_hash == node->p.reverse_hash)
+ goto insert;
+
+ next = rcu_dereference(clear_flag(iter)->p.next);
+ if (caa_unlikely(is_removed(next)))
+ goto gc_node;
+
+ /* uniquely add */
+ if (unique_ret
+ && !is_dummy(next)
+ && clear_flag(iter)->p.reverse_hash == node->p.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, &d_iter);
+ if (!d_iter.node)
+ goto insert;
+
+ *unique_ret = d_iter;
+ return;
+ }
+
+ /* 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, 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 (!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,
+ new_node) != iter) {
+ continue; /* retry */
+ } else {
+ return_node = node;
+ goto end;
+ }
+
+ gc_node:
+ assert(!is_removed(iter));
+ 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 */
+ }
+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,
+ int dummy_removal)
+{
+ struct cds_lfht_node *dummy, *next, *old;
+ struct _cds_lfht_node *lookup;
+
+ if (!node) /* Return -ENOENT if asked to delete NULL node */
+ return -ENOENT;
+
+ /* logically delete the node */
+ assert(!is_dummy(node));
+ assert(!is_removed(node));
+ old = rcu_dereference(node->p.next);
+ do {
+ struct cds_lfht_node *new_next;
+
+ next = old;
+ if (caa_unlikely(is_removed(next)))
+ return -ENOENT;
+ if (dummy_removal)
+ assert(is_dummy(next));
+ else
+ assert(!is_dummy(next));
+ new_next = flag_removed(next);
+ old = uatomic_cmpxchg(&node->p.next, next, new_next);
+ } while (old != next);
+ /* 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.
+ */
+ lookup = lookup_bucket(ht, size, bit_reverse_ulong(node->p.reverse_hash));
+ dummy = (struct cds_lfht_node *) lookup;
+ _cds_lfht_gc_bucket(dummy, node);
+
+ assert(is_removed(rcu_dereference(node->p.next)));
+ return 0;
+}
+
+static
+void *partition_resize_thread(void *arg)
+{
+ struct partition_resize_work *work = arg;
+
+ work->ht->cds_lfht_rcu_register_thread();
+ work->fct(work->ht, work->i, work->start, work->len);
+ work->ht->cds_lfht_rcu_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 >> 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 dummy 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;
+
+ assert(i > ht->min_alloc_order);
+ ht->cds_lfht_rcu_read_lock();
+ for (j = start; j < start + len; j++) {
+ struct cds_lfht_node *new_node =
+ (struct cds_lfht_node *) &ht->t.tbl[i]->nodes[j];
+
+ dbg_printf("init populate: i %lu j %lu hash %lu\n",
+ i, j, (1UL << (i - 1)) + j);
+ new_node->p.reverse_hash =
+ bit_reverse_ulong((1UL << (i - 1)) + j);
+ _cds_lfht_add(ht, 1UL << (i - 1),
+ new_node, NULL, 1);
+ }
+ ht->cds_lfht_rcu_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->cds_lfht_rcu_thread_online();
+ init_table_populate_partition(ht, i, 0, len);
+ ht->cds_lfht_rcu_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 > ht->min_alloc_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->t.resize_target) < (1UL << i))
+ break;
+
+ ht->t.tbl[i] = calloc(1, len * sizeof(struct _cds_lfht_node));
+ assert(ht->t.tbl[i]);
+
+ /*
+ * Set all dummy nodes reverse hash values for a level and
+ * link all dummy 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->t.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 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.
+ *
+ * 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;
+
+ assert(i > ht->min_alloc_order);
+ ht->cds_lfht_rcu_read_lock();
+ for (j = start; j < start + 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, (1UL << (i - 1)) + j);
+ fini_node->p.reverse_hash =
+ bit_reverse_ulong((1UL << (i - 1)) + j);
+ (void) _cds_lfht_del(ht, 1UL << (i - 1), fini_node, 1);
+ }
+ ht->cds_lfht_rcu_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->cds_lfht_rcu_thread_online();
+ remove_table_partition(ht, i, 0, len);
+ ht->cds_lfht_rcu_thread_offline();
+ return;
+ }
+ partition_resize_helper(ht, i, len, remove_table_partition);
+}
+
+static
+void fini_table(struct cds_lfht *ht,
+ unsigned long first_order, unsigned long last_order)
+{
+ long i;
+ void *free_by_rcu = NULL;
+
+ dbg_printf("fini table: first_order %lu last_order %lu\n",
+ first_order, last_order);
+ assert(first_order > ht->min_alloc_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->t.resize_target) > (1UL << (i - 1)))
+ break;
+
+ cmm_smp_wmb(); /* populate data before RCU size */
+ CMM_STORE_SHARED(ht->t.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 dummy nodes. Otherwise their lookup will
+ * return a logically removed node as insert position.
+ */
+ ht->cds_lfht_synchronize_rcu();
+ if (free_by_rcu)
+ free(free_by_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);
+
+ free_by_rcu = ht->t.tbl[i];
+
+ dbg_printf("fini new size: %lu\n", 1UL << i);
+ if (CMM_LOAD_SHARED(ht->in_progress_destroy))
+ break;
+ }
+
+ if (free_by_rcu) {
+ ht->cds_lfht_synchronize_rcu();
+ free(free_by_rcu);
+ }
+}
+
+static
+void cds_lfht_create_dummy(struct cds_lfht *ht, unsigned long size)
+{
+ struct _cds_lfht_node *prev, *node;
+ unsigned long order, len, i, j;
+
+ ht->t.tbl[0] = calloc(1, ht->min_alloc_size * sizeof(struct _cds_lfht_node));
+ assert(ht->t.tbl[0]);
+
+ dbg_printf("create dummy: order %lu index %lu hash %lu\n", 0, 0, 0);
+ ht->t.tbl[0]->nodes[0].next = flag_dummy(get_end());
+ ht->t.tbl[0]->nodes[0].reverse_hash = 0;
+
+ for (order = 1; order < get_count_order_ulong(size) + 1; order++) {
+ len = 1UL << (order - 1);
+ if (order <= ht->min_alloc_order) {
+ ht->t.tbl[order] = (struct rcu_level *) (ht->t.tbl[0]->nodes + len);
+ } else {
+ ht->t.tbl[order] = calloc(1, len * sizeof(struct _cds_lfht_node));
+ assert(ht->t.tbl[order]);
+ }
+
+ i = 0;
+ prev = ht->t.tbl[i]->nodes;
+ for (j = 0; j < len; j++) {
+ if (j & (j - 1)) { /* Between power of 2 */
+ prev++;
+ } else if (j) { /* At each power of 2 */
+ i++;
+ prev = ht->t.tbl[i]->nodes;
+ }
+
+ node = &ht->t.tbl[order]->nodes[j];
+ dbg_printf("create dummy: order %lu index %lu hash %lu\n",
+ order, j, j + len);
+ node->next = prev->next;
+ assert(is_dummy(node->next));
+ node->reverse_hash = bit_reverse_ulong(j + len);
+ prev->next = flag_dummy((struct cds_lfht_node *)node);
+ }
+ }
+}
+
+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,
+ unsigned long min_alloc_size,
+ int flags,
+ void (*cds_lfht_call_rcu)(struct rcu_head *head,
+ 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_thread_offline)(void),
+ void (*cds_lfht_rcu_thread_online)(void),
+ void (*cds_lfht_rcu_register_thread)(void),
+ void (*cds_lfht_rcu_unregister_thread)(void),
+ pthread_attr_t *attr)
+{
+ struct cds_lfht *ht;
+ unsigned long order;
+
+ /* min_alloc_size must be power of two */
+ if (!min_alloc_size || (min_alloc_size & (min_alloc_size - 1)))
+ return NULL;
+ /* init_size must be power of two */
+ if (!init_size || (init_size & (init_size - 1)))
+ return NULL;
+ min_alloc_size = max(min_alloc_size, MIN_TABLE_SIZE);
+ init_size = max(init_size, min_alloc_size);
+ ht = calloc(1, sizeof(struct cds_lfht));
+ assert(ht);
+ ht->flags = flags;
+ ht->hash_fct = hash_fct;
+ ht->compare_fct = compare_fct;
+ ht->hash_seed = hash_seed;
+ ht->cds_lfht_call_rcu = cds_lfht_call_rcu;
+ 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->cds_lfht_rcu_thread_offline = cds_lfht_rcu_thread_offline;
+ ht->cds_lfht_rcu_thread_online = cds_lfht_rcu_thread_online;
+ ht->cds_lfht_rcu_register_thread = cds_lfht_rcu_register_thread;
+ ht->cds_lfht_rcu_unregister_thread = cds_lfht_rcu_unregister_thread;
+ 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 = get_count_order_ulong(init_size);
+ ht->t.resize_target = 1UL << order;
+ ht->min_alloc_size = min_alloc_size;
+ ht->min_alloc_order = get_count_order_ulong(min_alloc_size);
+ cds_lfht_create_dummy(ht, 1UL << order);
+ ht->t.size = 1UL << order;
+ return ht;
+}
+
+void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
+ struct cds_lfht_iter *iter)
+{
+ struct cds_lfht_node *node, *next, *dummy_node;
+ struct _cds_lfht_node *lookup;
+ unsigned long hash, reverse_hash, size;
+
+ hash = ht->hash_fct(key, key_len, ht->hash_seed);
+ reverse_hash = bit_reverse_ulong(hash);
+
+ size = rcu_dereference(ht->t.size);
+ lookup = lookup_bucket(ht, size, hash);
+ dummy_node = (struct cds_lfht_node *) lookup;
+ /* We can always skip the dummy node initially */
+ node = rcu_dereference(dummy_node->p.next);
+ node = clear_flag(node);
+ for (;;) {
+ if (caa_unlikely(is_end(node))) {
+ node = next = NULL;
+ break;
+ }
+ if (caa_unlikely(node->p.reverse_hash > reverse_hash)) {
+ node = next = NULL;
+ break;
+ }
+ next = rcu_dereference(node->p.next);
+ assert(node == clear_flag(node));
+ if (caa_likely(!is_removed(next))
+ && !is_dummy(next)
+ && node->p.reverse_hash == reverse_hash
+ && caa_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)));
+ iter->node = node;
+ iter->next = next;
+}
+
+void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter)
+{
+ struct cds_lfht_node *node, *next;
+ unsigned long reverse_hash;
+ void *key;
+ size_t key_len;
+
+ node = iter->node;
+ reverse_hash = node->p.reverse_hash;
+ key = node->key;
+ key_len = node->key_len;
+ next = iter->next;
+ node = clear_flag(next);
+
+ for (;;) {
+ if (caa_unlikely(is_end(node))) {
+ node = next = NULL;
+ break;
+ }
+ if (caa_unlikely(node->p.reverse_hash > reverse_hash)) {
+ node = next = NULL;
+ break;
+ }
+ next = rcu_dereference(node->p.next);
+ if (caa_likely(!is_removed(next))
+ && !is_dummy(next)
+ && caa_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)));
+ 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->p.next);
+ if (caa_likely(!is_removed(next))
+ && !is_dummy(next)) {
+ break;
+ }
+ node = clear_flag(next);
+ }
+ assert(!node || !is_dummy(rcu_dereference(node->p.next)));
+ iter->node = node;
+ iter->next = next;
+}
+
+void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter)
+{
+ struct _cds_lfht_node *lookup;
+
+ /*
+ * Get next after first dummy node. The first dummy node is the
+ * first node of the linked list.
+ */
+ lookup = &ht->t.tbl[0]->nodes[0];
+ iter->next = lookup->next;
+ cds_lfht_next(ht, iter);
+}
+
+void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node)
+{
+ 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);
+
+ size = rcu_dereference(ht->t.size);
+ _cds_lfht_add(ht, size, node, NULL, 0);
+ ht_count_add(ht, size, hash);
+}
+
+struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
+ struct cds_lfht_node *node)
+{
+ unsigned long hash, size;
+ struct cds_lfht_iter iter;
+
+ hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
+ node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
+
+ size = rcu_dereference(ht->t.size);
+ _cds_lfht_add(ht, 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,
+ struct cds_lfht_node *node)
+{
+ unsigned long hash, size;
+ struct cds_lfht_iter iter;
+
+ hash = ht->hash_fct(node->key, node->key_len, ht->hash_seed);
+ node->p.reverse_hash = bit_reverse_ulong((unsigned long) hash);
+
+ size = rcu_dereference(ht->t.size);
+ for (;;) {
+ _cds_lfht_add(ht, 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,
+ struct cds_lfht_node *new_node)
+{
+ unsigned long size;
+
+ size = rcu_dereference(ht->t.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_iter *iter)
+{
+ unsigned long size, hash;
+ int ret;
+
+ size = rcu_dereference(ht->t.size);
+ ret = _cds_lfht_del(ht, size, iter->node, 0);
+ if (!ret) {
+ hash = bit_reverse_ulong(iter->node->p.reverse_hash);
+ ht_count_del(ht, size, hash);
+ }
+ return ret;
+}
+
+static
+int cds_lfht_delete_dummy(struct cds_lfht *ht)
+{
+ struct cds_lfht_node *node;
+ struct _cds_lfht_node *lookup;
+ unsigned long order, i, size;
+
+ /* Check that the table is empty */
+ lookup = &ht->t.tbl[0]->nodes[0];
+ node = (struct cds_lfht_node *) lookup;
+ do {
+ node = clear_flag(node)->p.next;
+ if (!is_dummy(node))
+ return -EPERM;
+ assert(!is_removed(node));
+ } while (!is_end(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(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(ht->t.tbl[order]->nodes[i].reverse_hash));
+ assert(is_dummy(ht->t.tbl[order]->nodes[i].next));
+ }
+
+ if (order == ht->min_alloc_order)
+ poison_free(ht->t.tbl[0]);
+ else if (order > ht->min_alloc_order)
+ poison_free(ht->t.tbl[order]);
+ /* Nothing to delete for order < ht->min_alloc_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_dummy(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,
+ unsigned long *removed,
+ long *approx_after)
+{
+ struct cds_lfht_node *node, *next;
+ struct _cds_lfht_node *lookup;
+ unsigned long nr_dummy = 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;
+ *removed = 0;
+
+ /* Count non-dummy nodes in the table */
+ lookup = &ht->t.tbl[0]->nodes[0];
+ node = (struct cds_lfht_node *) lookup;
+ do {
+ next = rcu_dereference(node->p.next);
+ if (is_removed(next)) {
+ if (!is_dummy(next))
+ (*removed)++;
+ else
+ (nr_dummy)++;
+ } else if (!is_dummy(next))
+ (*count)++;
+ else
+ (nr_dummy)++;
+ node = clear_flag(next);
+ } while (!is_end(node));
+ dbg_printf("number of dummy nodes: %lu\n", nr_dummy);
+ *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 = get_count_order_ulong(old_size);
+ new_order = get_count_order_ulong(new_size);
+ dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
+ old_size, old_order, new_size, new_order);
+ assert(new_size > old_size);
+ init_table(ht, old_order + 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, ht->min_alloc_size);
+ old_order = get_count_order_ulong(old_size);
+ new_order = get_count_order_ulong(new_size);
+ dbg_printf("resize from %lu (order %lu) to %lu (order %lu) buckets\n",
+ old_size, old_order, new_size, new_order);
+ assert(new_size < old_size);
+
+ /* Remove and unlink all dummy nodes to remove. */
+ fini_table(ht, new_order + 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->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 cds_lfht *ht, unsigned long size,
+ int growth_order)
+{
+ return _uatomic_max(&ht->t.resize_target,
+ size << growth_order);
+}
+
+static
+void resize_target_update_count(struct cds_lfht *ht,
+ unsigned long count)
+{
+ count = max(count, ht->min_alloc_size);
+ uatomic_set(&ht->t.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->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
+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->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, unsigned long size, int growth)
+{
+ struct rcu_resize_work *work;
+ unsigned long 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 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->cds_lfht_call_rcu(&work->head, do_resize_cb);
+ CMM_STORE_SHARED(ht->t.resize_initiated, 1);
+ }
+}
+
+static
+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(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 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->cds_lfht_call_rcu(&work->head, do_resize_cb);
+ CMM_STORE_SHARED(ht->t.resize_initiated, 1);
+ }
+}
projects / lttng-tools.git / blobdiff