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authorJustus Winter <4winter@informatik.uni-hamburg.de>2015-03-16 11:37:06 +0100
committerJustus Winter <4winter@informatik.uni-hamburg.de>2015-05-20 11:08:29 +0200
commit7d76ea075c248b2ed64c69a5e5dd4493d943e628 (patch)
tree9b8693e4d4509597d664b1aea1ff53c4fc17cd9c /kern/rdxtree.c
parent6eb79f812ee43a4e9142de61a5821e0cc8c52bb1 (diff)
kern: add radix tree library
Import a radix tree library from Richard Braun's librbraun. * Makefile.am (clib_routines): Steal `__ffsdi2'. * Makefrag.am (libkernel_a_SOURCES): Add new files. * kern/rdxtree.c: New file. * kern/rdxtree.h: Likewise. * kern/rdxtree_i.h: Likewise. * kern/startup.c (setup_main): Initialize radix tree library.
Diffstat (limited to 'kern/rdxtree.c')
-rw-r--r--kern/rdxtree.c830
1 files changed, 830 insertions, 0 deletions
diff --git a/kern/rdxtree.c b/kern/rdxtree.c
new file mode 100644
index 0000000..78868b1
--- /dev/null
+++ b/kern/rdxtree.c
@@ -0,0 +1,830 @@
+/*
+ * Copyright (c) 2011-2015 Richard Braun.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *
+ * Upstream site with license notes :
+ * http://git.sceen.net/rbraun/librbraun.git/
+ */
+
+#include <kern/assert.h>
+#include <kern/slab.h>
+#include <mach/kern_return.h>
+#include <stddef.h>
+#include <string.h>
+
+#include "macros.h"
+#include "rdxtree.h"
+#include "rdxtree_i.h"
+
+/* XXX */
+#define CHAR_BIT 8U
+#define ERR_SUCCESS KERN_SUCCESS
+#define ERR_BUSY KERN_INVALID_ARGUMENT
+#define ERR_NOMEM KERN_RESOURCE_SHORTAGE
+
+/*
+ * Mask applied on an entry to obtain its address.
+ */
+#define RDXTREE_ENTRY_ADDR_MASK (~0x3UL)
+
+/*
+ * Global properties used to shape radix trees.
+ */
+#define RDXTREE_RADIX 6
+#define RDXTREE_RADIX_SIZE (1UL << RDXTREE_RADIX)
+#define RDXTREE_RADIX_MASK (RDXTREE_RADIX_SIZE - 1)
+
+#if RDXTREE_RADIX < 6
+typedef unsigned long rdxtree_bm_t;
+#define rdxtree_ffs(x) __builtin_ffsl(x)
+#elif RDXTREE_RADIX == 6 /* RDXTREE_RADIX < 6 */
+typedef unsigned long long rdxtree_bm_t;
+#define rdxtree_ffs(x) __builtin_ffsll(x)
+#else /* RDXTREE_RADIX < 6 */
+#error "radix too high"
+#endif /* RDXTREE_RADIX < 6 */
+
+/*
+ * Allocation bitmap size in bits.
+ */
+#define RDXTREE_BM_SIZE (sizeof(rdxtree_bm_t) * CHAR_BIT)
+
+/*
+ * Empty/full allocation bitmap words.
+ */
+#define RDXTREE_BM_EMPTY ((rdxtree_bm_t)0)
+#define RDXTREE_BM_FULL \
+ ((~(rdxtree_bm_t)0) >> (RDXTREE_BM_SIZE - RDXTREE_RADIX_SIZE))
+
+/*
+ * These macros can be replaced by actual functions in an environment
+ * that provides lockless synchronization such as RCU.
+ */
+#define llsync_assign_ptr(ptr, value) ((ptr) = (value))
+#define llsync_read_ptr(ptr) (ptr)
+
+/*
+ * Radix tree node.
+ *
+ * The height of a tree is the number of nodes to traverse until stored
+ * pointers are reached. A height of 0 means the entries of a node (or the
+ * tree root) directly point to stored pointers.
+ *
+ * The index is valid if and only if the parent isn't NULL.
+ *
+ * Concerning the allocation bitmap, a bit is set when the node it denotes,
+ * or one of its children, can be used to allocate an entry. Conversely, a bit
+ * is clear when the matching node and all of its children have no free entry.
+ *
+ * In order to support safe lockless lookups, in particular during a resize,
+ * each node includes the height of its subtree, which is invariant during
+ * the entire node lifetime. Since the tree height does vary, it can't be
+ * used to determine whether the tree root is a node or a stored pointer.
+ * This implementation assumes that all nodes and stored pointers are at least
+ * 4-byte aligned, and uses the least significant bit of entries to indicate
+ * the pointer type. This bit is set for internal nodes, and clear for stored
+ * pointers so that they can be accessed from slots without conversion.
+ */
+struct rdxtree_node {
+ struct rdxtree_node *parent;
+ unsigned int index;
+ unsigned int height;
+ unsigned int nr_entries;
+ rdxtree_bm_t alloc_bm;
+ void *entries[RDXTREE_RADIX_SIZE];
+};
+
+/*
+ * We allocate nodes using the slab allocator.
+ */
+static struct kmem_cache rdxtree_node_cache;
+
+void
+rdxtree_cache_init(void)
+{
+ kmem_cache_init(&rdxtree_node_cache, "rdxtree_node",
+ sizeof(struct rdxtree_node), 0, NULL, NULL, NULL, 0);
+}
+
+#ifdef RDXTREE_ENABLE_NODE_CREATION_FAILURES
+unsigned int rdxtree_fail_node_creation_threshold;
+unsigned int rdxtree_nr_node_creations;
+#endif /* RDXTREE_ENABLE_NODE_CREATION_FAILURES */
+
+static inline int
+rdxtree_check_alignment(const void *ptr)
+{
+ return ((unsigned long)ptr & ~RDXTREE_ENTRY_ADDR_MASK) == 0;
+}
+
+static inline void *
+rdxtree_entry_addr(void *entry)
+{
+ return (void *)((unsigned long)entry & RDXTREE_ENTRY_ADDR_MASK);
+}
+
+static inline int
+rdxtree_entry_is_node(const void *entry)
+{
+ return ((unsigned long)entry & 1) != 0;
+}
+
+static inline void *
+rdxtree_node_to_entry(struct rdxtree_node *node)
+{
+ return (void *)((unsigned long)node | 1);
+}
+
+static int
+rdxtree_node_create(struct rdxtree_node **nodep, unsigned int height)
+{
+ struct rdxtree_node *node;
+
+#ifdef RDXTREE_ENABLE_NODE_CREATION_FAILURES
+ if (rdxtree_fail_node_creation_threshold != 0) {
+ rdxtree_nr_node_creations++;
+
+ if (rdxtree_nr_node_creations == rdxtree_fail_node_creation_threshold)
+ return ERR_NOMEM;
+ }
+#endif /* RDXTREE_ENABLE_NODE_CREATION_FAILURES */
+
+ node = (struct rdxtree_node *) kmem_cache_alloc(&rdxtree_node_cache);
+
+ if (node == NULL)
+ return ERR_NOMEM;
+
+ assert(rdxtree_check_alignment(node));
+ node->parent = NULL;
+ node->height = height;
+ node->nr_entries = 0;
+ node->alloc_bm = RDXTREE_BM_FULL;
+ memset(node->entries, 0, sizeof(node->entries));
+ *nodep = node;
+ return 0;
+}
+
+static void
+rdxtree_node_schedule_destruction(struct rdxtree_node *node)
+{
+ /*
+ * This function is intended to use the appropriate interface to defer
+ * destruction until all read-side references are dropped in an
+ * environment that provides lockless synchronization.
+ *
+ * Otherwise, it simply "schedules" destruction immediately.
+ */
+ kmem_cache_free(&rdxtree_node_cache, (vm_offset_t) node);
+}
+
+static inline void
+rdxtree_node_link(struct rdxtree_node *node, struct rdxtree_node *parent,
+ unsigned int index)
+{
+ node->parent = parent;
+ node->index = index;
+}
+
+static inline void
+rdxtree_node_unlink(struct rdxtree_node *node)
+{
+ assert(node->parent != NULL);
+ node->parent = NULL;
+}
+
+static inline int
+rdxtree_node_full(struct rdxtree_node *node)
+{
+ return (node->nr_entries == ARRAY_SIZE(node->entries));
+}
+
+static inline int
+rdxtree_node_empty(struct rdxtree_node *node)
+{
+ return (node->nr_entries == 0);
+}
+
+static inline void
+rdxtree_node_insert(struct rdxtree_node *node, unsigned int index,
+ void *entry)
+{
+ assert(index < ARRAY_SIZE(node->entries));
+ assert(node->entries[index] == NULL);
+
+ node->nr_entries++;
+ llsync_assign_ptr(node->entries[index], entry);
+}
+
+static inline void
+rdxtree_node_insert_node(struct rdxtree_node *node, unsigned int index,
+ struct rdxtree_node *child)
+{
+ rdxtree_node_insert(node, index, rdxtree_node_to_entry(child));
+}
+
+static inline void
+rdxtree_node_remove(struct rdxtree_node *node, unsigned int index)
+{
+ assert(index < ARRAY_SIZE(node->entries));
+ assert(node->entries[index] != NULL);
+
+ node->nr_entries--;
+ llsync_assign_ptr(node->entries[index], NULL);
+}
+
+static inline void *
+rdxtree_node_find(struct rdxtree_node *node, unsigned int *indexp)
+{
+ unsigned int index;
+ void *ptr;
+
+ index = *indexp;
+
+ while (index < ARRAY_SIZE(node->entries)) {
+ ptr = rdxtree_entry_addr(llsync_read_ptr(node->entries[index]));
+
+ if (ptr != NULL) {
+ *indexp = index;
+ return ptr;
+ }
+
+ index++;
+ }
+
+ return NULL;
+}
+
+static inline void
+rdxtree_node_bm_set(struct rdxtree_node *node, unsigned int index)
+{
+ node->alloc_bm |= (rdxtree_bm_t)1 << index;
+}
+
+static inline void
+rdxtree_node_bm_clear(struct rdxtree_node *node, unsigned int index)
+{
+ node->alloc_bm &= ~((rdxtree_bm_t)1 << index);
+}
+
+static inline int
+rdxtree_node_bm_is_set(struct rdxtree_node *node, unsigned int index)
+{
+ return (node->alloc_bm & ((rdxtree_bm_t)1 << index));
+}
+
+static inline int
+rdxtree_node_bm_empty(struct rdxtree_node *node)
+{
+ return (node->alloc_bm == RDXTREE_BM_EMPTY);
+}
+
+static inline unsigned int
+rdxtree_node_bm_first(struct rdxtree_node *node)
+{
+ return rdxtree_ffs(node->alloc_bm) - 1;
+}
+
+static inline rdxtree_key_t
+rdxtree_max_key(unsigned int height)
+{
+ size_t shift;
+
+ shift = RDXTREE_RADIX * height;
+
+ if (likely(shift < (sizeof(rdxtree_key_t) * CHAR_BIT)))
+ return ((rdxtree_key_t)1 << shift) - 1;
+ else
+ return ~((rdxtree_key_t)0);
+}
+
+static void
+rdxtree_shrink(struct rdxtree *tree)
+{
+ struct rdxtree_node *node;
+ void *entry;
+
+ while (tree->height > 0) {
+ node = rdxtree_entry_addr(tree->root);
+
+ if (node->nr_entries != 1)
+ break;
+
+ entry = node->entries[0];
+
+ if (entry == NULL)
+ break;
+
+ tree->height--;
+
+ if (tree->height > 0)
+ rdxtree_node_unlink(rdxtree_entry_addr(entry));
+
+ llsync_assign_ptr(tree->root, entry);
+ rdxtree_node_schedule_destruction(node);
+ }
+}
+
+static int
+rdxtree_grow(struct rdxtree *tree, rdxtree_key_t key)
+{
+ struct rdxtree_node *root, *node;
+ unsigned int new_height;
+ int error;
+
+ new_height = tree->height + 1;
+
+ while (key > rdxtree_max_key(new_height))
+ new_height++;
+
+ if (tree->root == NULL) {
+ tree->height = new_height;
+ return ERR_SUCCESS;
+ }
+
+ root = rdxtree_entry_addr(tree->root);
+
+ do {
+ error = rdxtree_node_create(&node, tree->height);
+
+ if (error) {
+ rdxtree_shrink(tree);
+ return error;
+ }
+
+ if (tree->height == 0)
+ rdxtree_node_bm_clear(node, 0);
+ else {
+ rdxtree_node_link(root, node, 0);
+
+ if (rdxtree_node_bm_empty(root))
+ rdxtree_node_bm_clear(node, 0);
+ }
+
+ rdxtree_node_insert(node, 0, tree->root);
+ tree->height++;
+ llsync_assign_ptr(tree->root, rdxtree_node_to_entry(node));
+ root = node;
+ } while (new_height > tree->height);
+
+ return ERR_SUCCESS;
+}
+
+static void
+rdxtree_cleanup(struct rdxtree *tree, struct rdxtree_node *node)
+{
+ struct rdxtree_node *prev;
+
+ for (;;) {
+ if (likely(!rdxtree_node_empty(node))) {
+ if (unlikely(node->parent == NULL))
+ rdxtree_shrink(tree);
+
+ break;
+ }
+
+ if (node->parent == NULL) {
+ tree->height = 0;
+ llsync_assign_ptr(tree->root, NULL);
+ rdxtree_node_schedule_destruction(node);
+ break;
+ }
+
+ prev = node;
+ node = node->parent;
+ rdxtree_node_unlink(prev);
+ rdxtree_node_remove(node, prev->index);
+ rdxtree_node_schedule_destruction(prev);
+ }
+}
+
+static void
+rdxtree_insert_bm_clear(struct rdxtree_node *node, unsigned int index)
+{
+ for (;;) {
+ rdxtree_node_bm_clear(node, index);
+
+ if (!rdxtree_node_full(node) || (node->parent == NULL))
+ break;
+
+ index = node->index;
+ node = node->parent;
+ }
+}
+
+int
+rdxtree_insert_common(struct rdxtree *tree, rdxtree_key_t key,
+ void *ptr, void ***slotp)
+{
+ struct rdxtree_node *node, *prev;
+ unsigned int height, shift, index = index;
+ int error;
+
+ assert(ptr != NULL);
+ assert(rdxtree_check_alignment(ptr));
+
+ if (unlikely(key > rdxtree_max_key(tree->height))) {
+ error = rdxtree_grow(tree, key);
+
+ if (error)
+ return error;
+ }
+
+ height = tree->height;
+
+ if (unlikely(height == 0)) {
+ if (tree->root != NULL)
+ return ERR_BUSY;
+
+ llsync_assign_ptr(tree->root, ptr);
+
+ if (slotp != NULL)
+ *slotp = &tree->root;
+
+ return ERR_SUCCESS;
+ }
+
+ node = rdxtree_entry_addr(tree->root);
+ shift = (height - 1) * RDXTREE_RADIX;
+ prev = NULL;
+
+ do {
+ if (node == NULL) {
+ error = rdxtree_node_create(&node, height - 1);
+
+ if (error) {
+ if (prev == NULL)
+ tree->height = 0;
+ else
+ rdxtree_cleanup(tree, prev);
+
+ return error;
+ }
+
+ if (prev == NULL)
+ llsync_assign_ptr(tree->root, rdxtree_node_to_entry(node));
+ else {
+ rdxtree_node_link(node, prev, index);
+ rdxtree_node_insert_node(prev, index, node);
+ }
+ }
+
+ prev = node;
+ index = (unsigned int)(key >> shift) & RDXTREE_RADIX_MASK;
+ node = rdxtree_entry_addr(prev->entries[index]);
+ shift -= RDXTREE_RADIX;
+ height--;
+ } while (height > 0);
+
+ if (unlikely(node != NULL))
+ return ERR_BUSY;
+
+ rdxtree_node_insert(prev, index, ptr);
+ rdxtree_insert_bm_clear(prev, index);
+
+ if (slotp != NULL)
+ *slotp = &prev->entries[index];
+
+ return ERR_SUCCESS;
+}
+
+int
+rdxtree_insert_alloc_common(struct rdxtree *tree, void *ptr,
+ rdxtree_key_t *keyp, void ***slotp)
+{
+ struct rdxtree_node *node, *prev;
+ unsigned int height, shift, index = index;
+ rdxtree_key_t key;
+ int error;
+
+ assert(ptr != NULL);
+ assert(rdxtree_check_alignment(ptr));
+
+ height = tree->height;
+
+ if (unlikely(height == 0)) {
+ if (tree->root == NULL) {
+ llsync_assign_ptr(tree->root, ptr);
+ *keyp = 0;
+
+ if (slotp != NULL)
+ *slotp = &tree->root;
+
+ return ERR_SUCCESS;
+ }
+
+ goto grow;
+ }
+
+ node = rdxtree_entry_addr(tree->root);
+ key = 0;
+ shift = (height - 1) * RDXTREE_RADIX;
+ prev = NULL;
+
+ do {
+ if (node == NULL) {
+ error = rdxtree_node_create(&node, height - 1);
+
+ if (error) {
+ rdxtree_cleanup(tree, prev);
+ return error;
+ }
+
+ rdxtree_node_link(node, prev, index);
+ rdxtree_node_insert_node(prev, index, node);
+ }
+
+ prev = node;
+ index = rdxtree_node_bm_first(node);
+
+ if (index == (unsigned int)-1)
+ goto grow;
+
+ key |= (rdxtree_key_t)index << shift;
+ node = rdxtree_entry_addr(node->entries[index]);
+ shift -= RDXTREE_RADIX;
+ height--;
+ } while (height > 0);
+
+ rdxtree_node_insert(prev, index, ptr);
+ rdxtree_insert_bm_clear(prev, index);
+
+ if (slotp != NULL)
+ *slotp = &prev->entries[index];
+
+ goto out;
+
+grow:
+ key = rdxtree_max_key(height) + 1;
+ error = rdxtree_insert_common(tree, key, ptr, slotp);
+
+ if (error)
+ return error;
+
+out:
+ *keyp = key;
+ return ERR_SUCCESS;
+}
+
+static void
+rdxtree_remove_bm_set(struct rdxtree_node *node, unsigned int index)
+{
+ do {
+ rdxtree_node_bm_set(node, index);
+
+ if (node->parent == NULL)
+ break;
+
+ index = node->index;
+ node = node->parent;
+ } while (!rdxtree_node_bm_is_set(node, index));
+}
+
+void *
+rdxtree_remove(struct rdxtree *tree, rdxtree_key_t key)
+{
+ struct rdxtree_node *node, *prev;
+ unsigned int height, shift, index;
+
+ height = tree->height;
+
+ if (unlikely(key > rdxtree_max_key(height)))
+ return NULL;
+
+ node = rdxtree_entry_addr(tree->root);
+
+ if (unlikely(height == 0)) {
+ llsync_assign_ptr(tree->root, NULL);
+ return node;
+ }
+
+ shift = (height - 1) * RDXTREE_RADIX;
+
+ do {
+ if (node == NULL)
+ return NULL;
+
+ prev = node;
+ index = (unsigned int)(key >> shift) & RDXTREE_RADIX_MASK;
+ node = rdxtree_entry_addr(node->entries[index]);
+ shift -= RDXTREE_RADIX;
+ height--;
+ } while (height > 0);
+
+ if (node == NULL)
+ return NULL;
+
+ rdxtree_node_remove(prev, index);
+ rdxtree_remove_bm_set(prev, index);
+ rdxtree_cleanup(tree, prev);
+ return node;
+}
+
+void *
+rdxtree_lookup_common(const struct rdxtree *tree, rdxtree_key_t key,
+ int get_slot)
+{
+ struct rdxtree_node *node, *prev;
+ unsigned int height, shift, index;
+ void *entry;
+
+ entry = llsync_read_ptr(tree->root);
+
+ if (entry == NULL) {
+ node = NULL;
+ height = 0;
+ } else {
+ node = rdxtree_entry_addr(entry);
+ height = rdxtree_entry_is_node(entry) ? node->height + 1 : 0;
+ }
+
+ if (key > rdxtree_max_key(height))
+ return NULL;
+
+ if (height == 0) {
+ if (node == NULL)
+ return NULL;
+
+ return get_slot ? (void *)&tree->root : node;
+ }
+
+ shift = (height - 1) * RDXTREE_RADIX;
+
+ do {
+ if (node == NULL)
+ return NULL;
+
+ prev = node;
+ index = (unsigned int)(key >> shift) & RDXTREE_RADIX_MASK;
+ entry = llsync_read_ptr(node->entries[index]);
+ node = rdxtree_entry_addr(entry);
+ shift -= RDXTREE_RADIX;
+ height--;
+ } while (height > 0);
+
+ if (node == NULL)
+ return NULL;
+
+ return get_slot ? (void *)&prev->entries[index] : node;
+}
+
+void *
+rdxtree_replace_slot(void **slot, void *ptr)
+{
+ void *old;
+
+ assert(ptr != NULL);
+ assert(rdxtree_check_alignment(ptr));
+
+ old = *slot;
+ assert(old != NULL);
+ assert(rdxtree_check_alignment(old));
+ llsync_assign_ptr(*slot, ptr);
+ return old;
+}
+
+static void *
+rdxtree_walk_next(struct rdxtree *tree, struct rdxtree_iter *iter)
+{
+ struct rdxtree_node *root, *node, *prev;
+ unsigned int height, shift, index, orig_index;
+ rdxtree_key_t key;
+ void *entry;
+
+ entry = llsync_read_ptr(tree->root);
+
+ if (entry == NULL)
+ return NULL;
+
+ if (!rdxtree_entry_is_node(entry)) {
+ if (iter->key != (rdxtree_key_t)-1)
+ return NULL;
+ else {
+ iter->key = 0;
+ return rdxtree_entry_addr(entry);
+ }
+ }
+
+ key = iter->key + 1;
+
+ if ((key == 0) && (iter->node != NULL))
+ return NULL;
+
+ root = rdxtree_entry_addr(entry);
+
+restart:
+ node = root;
+ height = root->height + 1;
+
+ if (key > rdxtree_max_key(height))
+ return NULL;
+
+ shift = (height - 1) * RDXTREE_RADIX;
+
+ do {
+ prev = node;
+ index = (key >> shift) & RDXTREE_RADIX_MASK;
+ orig_index = index;
+ node = rdxtree_node_find(node, &index);
+
+ if (node == NULL) {
+ shift += RDXTREE_RADIX;
+ key = ((key >> shift) + 1) << shift;
+
+ if (key == 0)
+ return NULL;
+
+ goto restart;
+ }
+
+ if (orig_index != index)
+ key = ((key >> shift) + (index - orig_index)) << shift;
+
+ shift -= RDXTREE_RADIX;
+ height--;
+ } while (height > 0);
+
+ iter->node = prev;
+ iter->key = key;
+ return node;
+}
+
+void *
+rdxtree_walk(struct rdxtree *tree, struct rdxtree_iter *iter)
+{
+ unsigned int index, orig_index;
+ void *ptr;
+
+ if (iter->node == NULL)
+ return rdxtree_walk_next(tree, iter);
+
+ index = (iter->key + 1) & RDXTREE_RADIX_MASK;
+
+ if (index != 0) {
+ orig_index = index;
+ ptr = rdxtree_node_find(iter->node, &index);
+
+ if (ptr != NULL) {
+ iter->key += (index - orig_index) + 1;
+ return ptr;
+ }
+ }
+
+ return rdxtree_walk_next(tree, iter);
+}
+
+void
+rdxtree_remove_all(struct rdxtree *tree)
+{
+ struct rdxtree_node *node, *parent;
+ struct rdxtree_iter iter;
+
+ if (tree->height == 0) {
+ if (tree->root != NULL)
+ llsync_assign_ptr(tree->root, NULL);
+
+ return;
+ }
+
+ for (;;) {
+ rdxtree_iter_init(&iter);
+ rdxtree_walk_next(tree, &iter);
+
+ if (iter.node == NULL)
+ break;
+
+ node = iter.node;
+ parent = node->parent;
+
+ if (parent == NULL)
+ rdxtree_init(tree);
+ else {
+ rdxtree_node_remove(parent, node->index);
+ rdxtree_remove_bm_set(parent, node->index);
+ rdxtree_cleanup(tree, parent);
+ node->parent = NULL;
+ }
+
+ rdxtree_node_schedule_destruction(node);
+ }
+}