--- /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, as well as traversals, and use the returned objects
+ * safely by allowing memory reclaim to take place only after 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 not to
+ * populate a duplicate key if the node key already exists in the hash
+ * table.
+ * - The resize operation executes concurrently with
+ * add/add_unique/add_replace/remove/lookup/traversal.
+ * - 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". These buckets are internal nodes that allow to
+ * perform a fast hash lookup, similarly to a skip list. These
+ * buckets are chained together in the split-ordered list, which
+ * allows recursive expansion by inserting new buckets between the
+ * existing buckets. The split-ordered list allows adding new buckets
+ * between existing buckets as the table needs to grow.
+ * - 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
+ * worker 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. After setting the "removal" flag,
+ * only the thread which removal is the first to set the "removal
+ * owner" flag (with an xchg) 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 it does not
+ * contain the "removed" node anymore, even if concurrent delete/add
+ * operations are changing the structure of the list concurrently.
+ * - The add operations perform garbage collection of buckets if they
+ * encounter nodes with removed flag set in the bucket where they want
+ * to add their 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.
+ * - There are three memory backends for the hash table buckets: the
+ * "order table", the "chunks", and the "mmap".
+ * - These bucket containers contain a compact version of the hash table
+ * nodes.
+ * - The RCU "order table":
+ * - has a first level table indexed by log2(hash index) which 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).
+ * - The RCU "chunks" is best suited for close interaction with a page
+ * allocator. It uses a linear array as index to "chunks" containing
+ * each the same number of buckets.
+ * - The RCU "mmap" memory backend uses a single memory map to hold
+ * all buckets.
+ * - synchronize_rcu is used to garbage-collect the old bucket node table.
+ *
+ * Ordering Guarantees:
+ *
+ * To discuss these guarantees, we first define "read" operation as any
+ * of the the basic lttng_ust_lfht_lookup, lttng_ust_lfht_next_duplicate,
+ * lttng_ust_lfht_first, lttng_ust_lfht_next operation, as well as
+ * lttng_ust_lfht_add_unique (failure).
+ *
+ * We define "read traversal" operation as any of the following
+ * group of operations
+ * - lttng_ust_lfht_lookup followed by iteration with lttng_ust_lfht_next_duplicate
+ * (and/or lttng_ust_lfht_next, although less common).
+ * - lttng_ust_lfht_add_unique (failure) followed by iteration with
+ * lttng_ust_lfht_next_duplicate (and/or lttng_ust_lfht_next, although less
+ * common).
+ * - lttng_ust_lfht_first followed iteration with lttng_ust_lfht_next (and/or
+ * lttng_ust_lfht_next_duplicate, although less common).
+ *
+ * We define "write" operations as any of lttng_ust_lfht_add, lttng_ust_lfht_replace,
+ * lttng_ust_lfht_add_unique (success), lttng_ust_lfht_add_replace, lttng_ust_lfht_del.
+ *
+ * When lttng_ust_lfht_add_unique succeeds (returns the node passed as
+ * parameter), it acts as a "write" operation. When lttng_ust_lfht_add_unique
+ * fails (returns a node different from the one passed as parameter), it
+ * acts as a "read" operation. A lttng_ust_lfht_add_unique failure is a
+ * lttng_ust_lfht_lookup "read" operation, therefore, any ordering guarantee
+ * referring to "lookup" imply any of "lookup" or lttng_ust_lfht_add_unique
+ * (failure).
+ *
+ * We define "prior" and "later" node as nodes observable by reads and
+ * read traversals respectively before and after a write or sequence of
+ * write operations.
+ *
+ * Hash-table operations are often cascaded, for example, the pointer
+ * returned by a lttng_ust_lfht_lookup() might be passed to a lttng_ust_lfht_next(),
+ * whose return value might in turn be passed to another hash-table
+ * operation. This entire cascaded series of operations must be enclosed
+ * by a pair of matching rcu_read_lock() and rcu_read_unlock()
+ * operations.
+ *
+ * The following ordering guarantees are offered by this hash table:
+ *
+ * A.1) "read" after "write": if there is ordering between a write and a
+ * later read, then the read is guaranteed to see the write or some
+ * later write.
+ * A.2) "read traversal" after "write": given that there is dependency
+ * ordering between reads in a "read traversal", if there is
+ * ordering between a write and the first read of the traversal,
+ * then the "read traversal" is guaranteed to see the write or
+ * some later write.
+ * B.1) "write" after "read": if there is ordering between a read and a
+ * later write, then the read will never see the write.
+ * B.2) "write" after "read traversal": given that there is dependency
+ * ordering between reads in a "read traversal", if there is
+ * ordering between the last read of the traversal and a later
+ * write, then the "read traversal" will never see the write.
+ * C) "write" while "read traversal": if a write occurs during a "read
+ * traversal", the traversal may, or may not, see the write.
+ * D.1) "write" after "write": if there is ordering between a write and
+ * a later write, then the later write is guaranteed to see the
+ * effects of the first write.
+ * D.2) Concurrent "write" pairs: The system will assign an arbitrary
+ * order to any pair of concurrent conflicting writes.
+ * Non-conflicting writes (for example, to different keys) are
+ * unordered.
+ * E) If a grace period separates a "del" or "replace" operation
+ * and a subsequent operation, then that subsequent operation is
+ * guaranteed not to see the removed item.
+ * F) Uniqueness guarantee: given a hash table that does not contain
+ * duplicate items for a given key, there will only be one item in
+ * the hash table after an arbitrary sequence of add_unique and/or
+ * add_replace operations. Note, however, that a pair of
+ * concurrent read operations might well access two different items
+ * with that key.
+ * G.1) If a pair of lookups for a given key are ordered (e.g. by a
+ * memory barrier), then the second lookup will return the same
+ * node as the previous lookup, or some later node.
+ * G.2) A "read traversal" that starts after the end of a prior "read
+ * traversal" (ordered by memory barriers) is guaranteed to see the
+ * same nodes as the previous traversal, or some later nodes.
+ * G.3) Concurrent "read" pairs: concurrent reads are unordered. For
+ * example, if a pair of reads to the same key run concurrently
+ * with an insertion of that same key, the reads remain unordered
+ * regardless of their return values. In other words, you cannot
+ * rely on the values returned by the reads to deduce ordering.
+ *
+ * Progress guarantees:
+ *
+ * * Reads are wait-free. These operations always move forward in the
+ * hash table linked list, and this list has no loop.
+ * * Writes are lock-free. Any retry loop performed by a write operation
+ * is triggered by progress made within another update operation.
+ *
+ * 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:
+ *
+ * The order index is the off-by-one compared 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
+ */
+
+/*
+ * Note on port to lttng-ust: auto-resize and accounting features are
+ * removed.
+ */
+
+#define _LGPL_SOURCE
+#include <stdlib.h>
+#include <errno.h>
+#include <assert.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <sched.h>
+#include <unistd.h>
+
+#include <lttng/urcu/pointer.h>
+#include <urcu/arch.h>
+#include <urcu/uatomic.h>
+#include <urcu/compiler.h>
+#include "rculfhash.h"
+#include "rculfhash-internal.h"
+#include <stdio.h>
+#include <pthread.h>
+#include <signal.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 support.
+ */
+#define COUNT_COMMIT_ORDER 10
+
+/*
+ * 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.
+ * The "removal owner" flag is used to detect which of the "del"
+ * operation that has set the "removed flag" gets to return the removed
+ * node to its caller. Note that the replace operation does not need to
+ * iteract with the "removal owner" flag, because it validates that
+ * the "removed" flag is not set before performing its cmpxchg.
+ */
+#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
+
+/*
+ * ht_items_count: Split-counters counting the number of node addition
+ * and removal in the table. Only used if the LTTNG_UST_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)));
+
+#ifdef CONFIG_LTTNG_UST_LFHT_ITER_DEBUG
+
+static
+void lttng_ust_lfht_iter_debug_set_ht(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
+{
+ iter->lfht = ht;
+}
+
+#define lttng_ust_lfht_iter_debug_assert(...) assert(__VA_ARGS__)
+
+#else
+
+static
+void lttng_ust_lfht_iter_debug_set_ht(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
+{
+}
+
+#define lttng_ust_lfht_iter_debug_assert(...)
+
+#endif
+
+/*
+ * 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];
+}
+
+#if (CAA_BITS_PER_LONG == 32)
+static
+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));
+}
+#else
+static
+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));
+}
+#endif
+
+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 lttng_ust_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 lttng_ust_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 lttng_ust_lfht_get_count_order_ulong(unsigned long x)
+{
+ if (!x)
+ return -1;
+
+ return lttng_ust_lfht_fls_ulong(x - 1);
+}
+
+static
+struct lttng_ust_lfht_node *clear_flag(struct lttng_ust_lfht_node *node)
+{
+ return (struct lttng_ust_lfht_node *) (((unsigned long) node) & ~FLAGS_MASK);
+}
+
+static
+int is_removed(const struct lttng_ust_lfht_node *node)
+{
+ return ((unsigned long) node) & REMOVED_FLAG;
+}
+
+static
+int is_bucket(struct lttng_ust_lfht_node *node)
+{
+ return ((unsigned long) node) & BUCKET_FLAG;
+}
+
+static
+struct lttng_ust_lfht_node *flag_bucket(struct lttng_ust_lfht_node *node)
+{
+ return (struct lttng_ust_lfht_node *) (((unsigned long) node) | BUCKET_FLAG);
+}
+
+static
+int is_removal_owner(struct lttng_ust_lfht_node *node)
+{
+ return ((unsigned long) node) & REMOVAL_OWNER_FLAG;
+}
+
+static
+struct lttng_ust_lfht_node *flag_removal_owner(struct lttng_ust_lfht_node *node)
+{
+ return (struct lttng_ust_lfht_node *) (((unsigned long) node) | REMOVAL_OWNER_FLAG);
+}
+
+static
+struct lttng_ust_lfht_node *flag_removed_or_removal_owner(struct lttng_ust_lfht_node *node)
+{
+ return (struct lttng_ust_lfht_node *) (((unsigned long) node) | REMOVED_FLAG | REMOVAL_OWNER_FLAG);
+}
+
+static
+struct lttng_ust_lfht_node *get_end(void)
+{
+ return (struct lttng_ust_lfht_node *) END_VALUE;
+}
+
+static
+int is_end(struct lttng_ust_lfht_node *node)
+{
+ return clear_flag(node) == (struct lttng_ust_lfht_node *) END_VALUE;
+}
+
+static
+void lttng_ust_lfht_alloc_bucket_table(struct lttng_ust_lfht *ht, unsigned long order)
+{
+ return ht->mm->alloc_bucket_table(ht, order);
+}
+
+/*
+ * lttng_ust_lfht_free_bucket_table() should be called with decreasing order.
+ * When lttng_ust_lfht_free_bucket_table(0) is called, it means the whole
+ * lfht is destroyed.
+ */
+static
+void lttng_ust_lfht_free_bucket_table(struct lttng_ust_lfht *ht, unsigned long order)
+{
+ return ht->mm->free_bucket_table(ht, order);
+}
+
+static inline
+struct lttng_ust_lfht_node *bucket_at(struct lttng_ust_lfht *ht, unsigned long index)
+{
+ return ht->bucket_at(ht, index);
+}
+
+static inline
+struct lttng_ust_lfht_node *lookup_bucket(struct lttng_ust_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 _lttng_ust_lfht_gc_bucket(struct lttng_ust_lfht_node *bucket, struct lttng_ust_lfht_node *node)
+{
+ struct lttng_ust_lfht_node *iter_prev, *iter, *next, *new_next;
+
+ assert(!is_bucket(bucket));
+ assert(!is_removed(bucket));
+ assert(!is_removal_owner(bucket));
+ assert(!is_bucket(node));
+ assert(!is_removed(node));
+ assert(!is_removal_owner(node));
+ for (;;) {
+ iter_prev = bucket;
+ /* We can always skip the bucket node initially */
+ iter = lttng_ust_rcu_dereference(iter_prev->next);
+ assert(!is_removed(iter));
+ assert(!is_removal_owner(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 = lttng_ust_rcu_dereference(clear_flag(iter)->next);
+ if (caa_likely(is_removed(next)))
+ break;
+ iter_prev = clear_flag(iter);
+ iter = next;
+ }
+ assert(!is_removed(iter));
+ assert(!is_removal_owner(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 _lttng_ust_lfht_replace(struct lttng_ust_lfht *ht, unsigned long size,
+ struct lttng_ust_lfht_node *old_node,
+ struct lttng_ust_lfht_node *old_next,
+ struct lttng_ust_lfht_node *new_node)
+{
+ struct lttng_ust_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_removal_owner(old_node));
+ assert(!is_bucket(old_node));
+ assert(!is_removed(new_node));
+ assert(!is_removal_owner(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);
+ /*
+ * REMOVAL_OWNER flag is _NEVER_ set before the REMOVED
+ * flag. It is either set atomically at the same time
+ * (replace) or after (del).
+ */
+ assert(!is_removal_owner(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. We set both the
+ * REMOVED and REMOVAL_OWNER flags atomically so we own
+ * the node after successful cmpxchg.
+ */
+ ret_next = uatomic_cmpxchg(&old_node->next,
+ old_next, flag_removed_or_removal_owner(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));
+ _lttng_ust_lfht_gc_bucket(bucket, new_node);
+
+ assert(is_removed(CMM_LOAD_SHARED(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 _lttng_ust_lfht_add(struct lttng_ust_lfht *ht,
+ unsigned long hash,
+ lttng_ust_lfht_match_fct match,
+ const void *key,
+ unsigned long size,
+ struct lttng_ust_lfht_node *node,
+ struct lttng_ust_lfht_iter *unique_ret,
+ int bucket_flag)
+{
+ struct lttng_ust_lfht_node *iter_prev, *iter, *next, *new_node, *new_next,
+ *return_node;
+ struct lttng_ust_lfht_node *bucket;
+
+ assert(!is_bucket(node));
+ assert(!is_removed(node));
+ assert(!is_removal_owner(node));
+ bucket = lookup_bucket(ht, size, hash);
+ for (;;) {
+ /*
+ * 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 = lttng_ust_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 = lttng_ust_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 lttng_ust_lfht_iter d_iter = {
+ .node = node,
+ .next = iter,
+#ifdef CONFIG_LTTNG_UST_LFHT_ITER_DEBUG
+ .lfht = ht,
+#endif
+ };
+
+ /*
+ * 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 traversing the table node by
+ * node by forward iterations)
+ */
+ lttng_ust_lfht_next_duplicate(ht, match, key, &d_iter);
+ if (!d_iter.node)
+ goto insert;
+
+ *unique_ret = d_iter;
+ return;
+ }
+
+ iter_prev = clear_flag(iter);
+ iter = next;
+ }
+
+ insert:
+ assert(node != clear_flag(iter));
+ assert(!is_removed(iter_prev));
+ assert(!is_removal_owner(iter_prev));
+ assert(!is_removed(iter));
+ assert(!is_removal_owner(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));
+ assert(!is_removal_owner(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 _lttng_ust_lfht_del(struct lttng_ust_lfht *ht, unsigned long size,
+ struct lttng_ust_lfht_node *node)
+{
+ struct lttng_ust_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 = CMM_LOAD_SHARED(node->next); /* next is not dereferenced */
+ if (caa_unlikely(is_removed(next)))
+ return -ENOENT;
+ assert(!is_bucket(next));
+ /*
+ * The del operation semantic guarantees a full memory barrier
+ * before the uatomic_or atomic commit of the deletion flag.
+ */
+ cmm_smp_mb__before_uatomic_or();
+ /*
+ * 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));
+ _lttng_ust_lfht_gc_bucket(bucket, node);
+
+ assert(is_removed(CMM_LOAD_SHARED(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;
+}
+
+/*
+ * Never called with size < 1.
+ */
+static
+void lttng_ust_lfht_create_bucket(struct lttng_ust_lfht *ht, unsigned long size)
+{
+ struct lttng_ust_lfht_node *prev, *node;
+ unsigned long order, len, i;
+ int bucket_order;
+
+ lttng_ust_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;
+
+ bucket_order = lttng_ust_lfht_get_count_order_ulong(size);
+ assert(bucket_order >= 0);
+
+ for (order = 1; order < (unsigned long) bucket_order + 1; order++) {
+ len = 1UL << (order - 1);
+ lttng_ust_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);
+ }
+ }
+}
+
+#if (CAA_BITS_PER_LONG > 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. Otherwise,
+ * fallback to the order allocator.
+ */
+static
+const struct lttng_ust_lfht_mm_type *get_mm_type(unsigned long max_nr_buckets)
+{
+ if (max_nr_buckets && max_nr_buckets <= (1ULL << 32))
+ return <tng_ust_lfht_mm_mmap;
+ else
+ return <tng_ust_lfht_mm_order;
+}
+#else
+/*
+ * For 32-bit architectures, use the order allocator.
+ */
+static
+const struct lttng_ust_lfht_mm_type *get_mm_type(unsigned long max_nr_buckets)
+{
+ return <tng_ust_lfht_mm_order;
+}
+#endif
+
+struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size,
+ unsigned long min_nr_alloc_buckets,
+ unsigned long max_nr_buckets,
+ int flags,
+ const struct lttng_ust_lfht_mm_type *mm)
+{
+ struct lttng_ust_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)
+ mm = get_mm_type(max_nr_buckets);
+
+ /* max_nr_buckets == 0 for order based mm means infinite */
+ if (mm == <tng_ust_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;
+
+ if (flags & LTTNG_UST_LFHT_AUTO_RESIZE)
+ 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_lttng_ust_lfht(min_nr_alloc_buckets, max_nr_buckets);
+ assert(ht);
+ assert(ht->mm == mm);
+ assert(ht->bucket_at == mm->bucket_at);
+
+ ht->flags = flags;
+ /* this mutex should not nest in read-side C.S. */
+ pthread_mutex_init(&ht->resize_mutex, NULL);
+ order = lttng_ust_lfht_get_count_order_ulong(init_size);
+ ht->resize_target = 1UL << order;
+ lttng_ust_lfht_create_bucket(ht, 1UL << order);
+ ht->size = 1UL << order;
+ return ht;
+}
+
+void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash,
+ lttng_ust_lfht_match_fct match, const void *key,
+ struct lttng_ust_lfht_iter *iter)
+{
+ struct lttng_ust_lfht_node *node, *next, *bucket;
+ unsigned long reverse_hash, size;
+
+ lttng_ust_lfht_iter_debug_set_ht(ht, iter);
+
+ reverse_hash = bit_reverse_ulong(hash);
+
+ size = lttng_ust_rcu_dereference(ht->size);
+ bucket = lookup_bucket(ht, size, hash);
+ /* We can always skip the bucket node initially */
+ node = lttng_ust_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 = lttng_ust_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(CMM_LOAD_SHARED(node->next)));
+ iter->node = node;
+ iter->next = next;
+}
+
+void lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht, lttng_ust_lfht_match_fct match,
+ const void *key, struct lttng_ust_lfht_iter *iter)
+{
+ struct lttng_ust_lfht_node *node, *next;
+ unsigned long reverse_hash;
+
+ lttng_ust_lfht_iter_debug_assert(ht == iter->lfht);
+ 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 = lttng_ust_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(CMM_LOAD_SHARED(node->next)));
+ iter->node = node;
+ iter->next = next;
+}
+
+void lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
+{
+ struct lttng_ust_lfht_node *node, *next;
+
+ lttng_ust_lfht_iter_debug_assert(ht == iter->lfht);
+ node = clear_flag(iter->next);
+ for (;;) {
+ if (caa_unlikely(is_end(node))) {
+ node = next = NULL;
+ break;
+ }
+ next = lttng_ust_rcu_dereference(node->next);
+ if (caa_likely(!is_removed(next))
+ && !is_bucket(next)) {
+ break;
+ }
+ node = clear_flag(next);
+ }
+ assert(!node || !is_bucket(CMM_LOAD_SHARED(node->next)));
+ iter->node = node;
+ iter->next = next;
+}
+
+void lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter)
+{
+ lttng_ust_lfht_iter_debug_set_ht(ht, 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;
+ lttng_ust_lfht_next(ht, iter);
+}
+
+void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash,
+ struct lttng_ust_lfht_node *node)
+{
+ unsigned long size;
+
+ node->reverse_hash = bit_reverse_ulong(hash);
+ size = lttng_ust_rcu_dereference(ht->size);
+ _lttng_ust_lfht_add(ht, hash, NULL, NULL, size, node, NULL, 0);
+}
+
+struct lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht,
+ unsigned long hash,
+ lttng_ust_lfht_match_fct match,
+ const void *key,
+ struct lttng_ust_lfht_node *node)
+{
+ unsigned long size;
+ struct lttng_ust_lfht_iter iter;
+
+ node->reverse_hash = bit_reverse_ulong(hash);
+ size = lttng_ust_rcu_dereference(ht->size);
+ _lttng_ust_lfht_add(ht, hash, match, key, size, node, &iter, 0);
+ return iter.node;
+}
+
+struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht,
+ unsigned long hash,
+ lttng_ust_lfht_match_fct match,
+ const void *key,
+ struct lttng_ust_lfht_node *node)
+{
+ unsigned long size;
+ struct lttng_ust_lfht_iter iter;
+
+ node->reverse_hash = bit_reverse_ulong(hash);
+ size = lttng_ust_rcu_dereference(ht->size);
+ for (;;) {
+ _lttng_ust_lfht_add(ht, hash, match, key, size, node, &iter, 0);
+ if (iter.node == node) {
+ return NULL;
+ }
+
+ if (!_lttng_ust_lfht_replace(ht, size, iter.node, iter.next, node))
+ return iter.node;
+ }
+}
+
+int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht,
+ struct lttng_ust_lfht_iter *old_iter,
+ unsigned long hash,
+ lttng_ust_lfht_match_fct match,
+ const void *key,
+ struct lttng_ust_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 = lttng_ust_rcu_dereference(ht->size);
+ return _lttng_ust_lfht_replace(ht, size, old_iter->node, old_iter->next,
+ new_node);
+}
+
+int lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node)
+{
+ unsigned long size;
+
+ size = lttng_ust_rcu_dereference(ht->size);
+ return _lttng_ust_lfht_del(ht, size, node);
+}
+
+int lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node)
+{
+ return is_removed(CMM_LOAD_SHARED(node->next));
+}
+
+static
+int lttng_ust_lfht_delete_bucket(struct lttng_ust_lfht *ht)
+{
+ struct lttng_ust_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));
+ assert(!is_removal_owner(node));
+ } while (!is_end(node));
+ /*
+ * size accessed without lttng_ust_rcu_dereference because hash table is
+ * being destroyed.
+ */
+ size = ht->size;
+ /* Internal sanity check: all nodes left should be buckets */
+ 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 = lttng_ust_lfht_get_count_order_ulong(size); (long)order >= 0; order--)
+ lttng_ust_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 lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht)
+{
+ int ret;
+
+ ret = lttng_ust_lfht_delete_bucket(ht);
+ if (ret)
+ return ret;
+ ret = pthread_mutex_destroy(&ht->resize_mutex);
+ if (ret)
+ ret = -EBUSY;
+ poison_free(ht);
+ return ret;
+}
projects / deliverable / lttng-ust.git / blobdiff