+++ /dev/null
-/*
- * SPDX-License-Identifier: LGPL-2.1-or-later
- *
- * Copyright 2010-2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com>
- *
- * Userspace RCU library - Lock-Free Resizable RCU Hash Table
- */
-
-/*
- * 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/ust-arch.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 __attribute__((unused)),
- struct lttng_ust_lfht_iter *iter __attribute__((unused)))
-{
-}
-
-#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(LTTNG_UST_ARCH_X86)
-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(LTTNG_UST_ARCH_AMD64)
-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
-unsigned int fls_u64(uint64_t x)
- __attribute__((unused));
-static
-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
-unsigned int fls_u32(uint32_t x)
- __attribute__((unused));
-static
-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 __attribute__((unused)),
- 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 __attribute__((unused)),
- 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 / lttng-ust.git / blobdiff