git: 90710f4a3473 - main - pctrie: add parent pointer to nodes
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Date: Mon, 10 Feb 2025 20:20:07 UTC
The branch main has been updated by dougm:
URL: https://cgit.FreeBSD.org/src/commit/?id=90710f4a3473f7cf0dd1cfa17a7c3176cc471c71
commit 90710f4a3473f7cf0dd1cfa17a7c3176cc471c71
Author: Doug Moore <dougm@FreeBSD.org>
AuthorDate: 2025-02-10 20:17:28 +0000
Commit: Doug Moore <dougm@FreeBSD.org>
CommitDate: 2025-02-10 20:17:28 +0000
pctrie: add parent pointer to nodes
Add a parent pointer field to the pctrie_node struct, and maintain
it as part of inserting and removing pctrie items.
Much code is written to maintain one, or an array, of trailing
pointers; that maintenance can be dropped with parent pointers
available. Code affected includes remove, reclaim, lookup_le, and
lookup_ge. In places, functions written once for iterator-free
searching and again for iterator-maintaining searching can be replaced
with a single function that serves both purposes.
Fix an overflow error in lower-bound testing for lookup_le.
Reviewed by: markj
Tested by: pho
Differential Revision: https://reviews.freebsd.org/D48588
---
sys/kern/subr_pctrie.c | 656 ++++++++++++++++---------------------------------
sys/sys/pctrie.h | 162 +++++-------
2 files changed, 268 insertions(+), 550 deletions(-)
diff --git a/sys/kern/subr_pctrie.c b/sys/kern/subr_pctrie.c
index a078f0587f37..16690c3521bf 100644
--- a/sys/kern/subr_pctrie.c
+++ b/sys/kern/subr_pctrie.c
@@ -81,6 +81,7 @@ struct pctrie_node {
uint64_t pn_owner; /* Owner of record. */
pn_popmap_t pn_popmap; /* Valid children. */
uint8_t pn_clev; /* Level * WIDTH. */
+ smr_pctnode_t pn_parent; /* Parent node. */
smr_pctnode_t pn_child[PCTRIE_COUNT]; /* Child nodes. */
};
@@ -107,28 +108,6 @@ pctrie_keybarr(struct pctrie_node *node, uint64_t index, int *slot)
return (false);
}
-/*
- * Check radix node.
- */
-static __inline void
-pctrie_node_put(struct pctrie_node *node)
-{
-#ifdef INVARIANTS
- int slot;
-
- KASSERT(powerof2(node->pn_popmap),
- ("pctrie_node_put: node %p has too many children %04x", node,
- node->pn_popmap));
- for (slot = 0; slot < PCTRIE_COUNT; slot++) {
- if ((node->pn_popmap & (1 << slot)) != 0)
- continue;
- KASSERT(smr_unserialized_load(&node->pn_child[slot], true) ==
- PCTRIE_NULL,
- ("pctrie_node_put: node %p has a child", node));
- }
-#endif
-}
-
enum pctrie_access { PCTRIE_SMR, PCTRIE_LOCKED, PCTRIE_UNSERIALIZED };
/*
@@ -185,6 +164,16 @@ pctrie_root_load(struct pctrie *ptree, smr_t smr, enum pctrie_access access)
return (pctrie_node_load(pctrie_root(ptree), smr, access));
}
+/*
+ * Get the child of a node.
+ */
+static __inline smr_pctnode_t *
+pctrie_child(struct pctrie *ptree, struct pctrie_node *node, uint64_t index)
+{
+ return (node == NULL ? pctrie_root(ptree) :
+ &node->pn_child[pctrie_slot(node, index)]);
+}
+
/*
* Returns TRUE if the specified node is a leaf and FALSE otherwise.
*/
@@ -221,6 +210,24 @@ pctrie_toptr(struct pctrie_node *node, int keyoff)
return ((void *)(((uintptr_t)node & ~PCTRIE_FLAGS) - keyoff));
}
+/*
+ * Make 'parent' a parent of 'child'.
+ */
+static __inline void
+pctrie_setparent(struct pctrie_node *child, struct pctrie_node *parent)
+{
+ pctrie_node_store(&child->pn_parent, parent, PCTRIE_UNSERIALIZED);
+}
+
+/*
+ * Return the parent of 'node'.
+ */
+static __inline struct pctrie_node *
+pctrie_parent(struct pctrie_node *node)
+{
+ return (pctrie_node_load(&node->pn_parent, NULL, PCTRIE_UNSERIALIZED));
+}
+
/*
* Make 'child' a child of 'node'.
*/
@@ -260,12 +267,6 @@ pctrie_node_size(void)
return (sizeof(struct pctrie_node));
}
-enum pctrie_insert_neighbor_mode {
- PCTRIE_INSERT_NEIGHBOR_NONE,
- PCTRIE_INSERT_NEIGHBOR_LT,
- PCTRIE_INSERT_NEIGHBOR_GT,
-};
-
/*
* Look for where to insert the key-value pair into the trie. Complete the
* insertion if it replaces a null leaf. Return the insertion location if the
@@ -273,19 +274,10 @@ enum pctrie_insert_neighbor_mode {
*
* If the key is already present in the trie, populate *found_out as if by
* pctrie_lookup().
- *
- * With mode PCTRIE_INSERT_NEIGHBOR_GT or PCTRIE_INSERT_NEIGHBOR_LT, set
- * *neighbor_out to the lowest level node we encounter during the insert lookup
- * that is a parent of the next greater or lesser entry. The value is not
- * defined if the key was already present in the trie.
- *
- * Note that mode is expected to be a compile-time constant, and this procedure
- * is expected to be inlined into callers with extraneous code optimized out.
*/
static __always_inline void *
pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val,
- uint64_t **found_out, struct pctrie_node **neighbor_out,
- enum pctrie_insert_neighbor_mode mode)
+ struct pctrie_node **parent_out, uint64_t **found_out)
{
uint64_t index;
struct pctrie_node *node, *parent;
@@ -308,51 +300,29 @@ pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val,
else
pctrie_addnode(parent, index,
pctrie_toleaf(val), PCTRIE_LOCKED);
+ *parent_out = parent;
return (NULL);
}
if (*pctrie_toval(node) == index) {
*found_out = pctrie_toval(node);
+ *parent_out = parent;
return (NULL);
}
break;
}
if (pctrie_keybarr(node, index, &slot))
break;
- /*
- * Descend. If we're tracking the next neighbor and this node
- * contains a neighboring entry in the right direction, record
- * it.
- */
- if (mode == PCTRIE_INSERT_NEIGHBOR_LT) {
- if ((node->pn_popmap & ((1 << slot) - 1)) != 0)
- *neighbor_out = node;
- } else if (mode == PCTRIE_INSERT_NEIGHBOR_GT) {
- if ((node->pn_popmap >> slot) > 1)
- *neighbor_out = node;
- }
parent = node;
node = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
- /*
- * The caller will split this node. If we're tracking the next
- * neighbor, record the old node if the old entry is in the right
- * direction.
- */
- if (mode == PCTRIE_INSERT_NEIGHBOR_LT) {
- if (*pctrie_toval(node) < index)
- *neighbor_out = node;
- } else if (mode == PCTRIE_INSERT_NEIGHBOR_GT) {
- if (*pctrie_toval(node) > index)
- *neighbor_out = node;
- }
-
/*
* 'node' must be replaced in the tree with a new branch node, with
* children 'node' and 'val'. Return the place that points to 'node'
* now, and will point to to the new branching node later.
*/
+ *parent_out = parent;
return ((parent == NULL) ? pctrie_root(ptree): &parent->pn_child[slot]);
}
@@ -361,14 +331,15 @@ pctrie_insert_lookup_compound(struct pctrie *ptree, uint64_t *val,
* if the key already exists, and do not look for neighboring entries.
*/
void *
-pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val)
+pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val,
+ struct pctrie_node **parent_out)
{
void *parentp;
uint64_t *found;
found = NULL;
- parentp = pctrie_insert_lookup_compound(ptree, val, &found, NULL,
- PCTRIE_INSERT_NEIGHBOR_NONE);
+ parentp = pctrie_insert_lookup_compound(ptree, val, parent_out,
+ &found);
if (__predict_false(found != NULL))
panic("%s: key %jx is already present", __func__,
(uintmax_t)*val);
@@ -381,71 +352,47 @@ pctrie_insert_lookup_strict(struct pctrie *ptree, uint64_t *val)
*/
void *
pctrie_insert_lookup(struct pctrie *ptree, uint64_t *val,
- uint64_t **found_out)
-{
- *found_out = NULL;
- return (pctrie_insert_lookup_compound(ptree, val, found_out, NULL,
- PCTRIE_INSERT_NEIGHBOR_NONE));
-}
-
-/*
- * Wrap pctrie_insert_lookup_compound to implement find or insert and find next
- * greater entry. Find a subtree that contains the next entry greater than the
- * newly-inserted or to-be-inserted entry.
- */
-void *
-pctrie_insert_lookup_gt(struct pctrie *ptree, uint64_t *val,
- uint64_t **found_out, struct pctrie_node **neighbor_out)
+ struct pctrie_node **parent_out, uint64_t **found_out)
{
*found_out = NULL;
- *neighbor_out = NULL;
- return (pctrie_insert_lookup_compound(ptree, val, found_out,
- neighbor_out, PCTRIE_INSERT_NEIGHBOR_GT));
+ return (pctrie_insert_lookup_compound(ptree, val, parent_out,
+ found_out));
}
/*
- * Wrap pctrie_insert_lookup_compound to implement find or insert and find next
- * lesser entry. Find a subtree that contains the next entry less than the
- * newly-inserted or to-be-inserted entry.
- */
-void *
-pctrie_insert_lookup_lt(struct pctrie *ptree, uint64_t *val,
- uint64_t **found_out, struct pctrie_node **neighbor_out)
-{
- *found_out = NULL;
- *neighbor_out = NULL;
- return (pctrie_insert_lookup_compound(ptree, val, found_out,
- neighbor_out, PCTRIE_INSERT_NEIGHBOR_LT));
-}
-
-/*
- * Uses new node to insert key-value pair into the trie at given location.
+ * Inserts newly allocated node 'child' into trie at location 'parentp', with
+ * parent 'parent' and two children, 'val' and whatever non-NULL node or leaf
+ * was at 'parentp' to begin with.
*/
void
-pctrie_insert_node(void *parentp, struct pctrie_node *parent, uint64_t *val)
+pctrie_insert_node(uint64_t *val, struct pctrie_node *parent, void *parentp,
+ struct pctrie_node *child)
{
struct pctrie_node *node;
uint64_t index, newind;
/*
- * Clear the last child pointer of the newly allocated parent. We want
+ * Clear the last child pointer of the newly allocated child. We want
* to clear it after the final section has exited so lookup can not
* return false negatives. It is done here because it will be
* cache-cold in the dtor callback.
*/
- if (parent->pn_popmap != 0) {
- pctrie_node_store(&parent->pn_child[ffs(parent->pn_popmap) - 1],
+ if (child->pn_popmap != 0) {
+ pctrie_node_store(&child->pn_child[ffs(child->pn_popmap) - 1],
PCTRIE_NULL, PCTRIE_UNSERIALIZED);
- parent->pn_popmap = 0;
+ child->pn_popmap = 0;
}
/*
- * Recover the values of the two children of the new parent node. If
+ * Recover the values of the two children of the new child node. If
* 'node' is not a leaf, this stores into 'newind' the 'owner' field,
* which must be first in the node.
*/
index = *val;
node = pctrie_node_load(parentp, NULL, PCTRIE_UNSERIALIZED);
+ pctrie_setparent(child, parent);
+ if (!pctrie_isleaf(node))
+ pctrie_setparent(node, child);
newind = *pctrie_toval(node);
/*
@@ -456,17 +403,17 @@ pctrie_insert_node(void *parentp, struct pctrie_node *parent, uint64_t *val)
_Static_assert(sizeof(long long) >= sizeof(uint64_t),
"uint64 too wide");
_Static_assert(sizeof(uint64_t) * NBBY <=
- (1 << (sizeof(parent->pn_clev) * NBBY)), "pn_clev too narrow");
- parent->pn_clev = rounddown(ilog2(index ^ newind), PCTRIE_WIDTH);
- parent->pn_owner = PCTRIE_COUNT;
- parent->pn_owner = index & -(parent->pn_owner << parent->pn_clev);
+ (1 << (sizeof(child->pn_clev) * NBBY)), "pn_clev too narrow");
+ child->pn_clev = rounddown(ilog2(index ^ newind), PCTRIE_WIDTH);
+ child->pn_owner = PCTRIE_COUNT;
+ child->pn_owner = index & -(child->pn_owner << child->pn_clev);
/* These writes are not yet visible due to ordering. */
- pctrie_addnode(parent, index, pctrie_toleaf(val), PCTRIE_UNSERIALIZED);
- pctrie_addnode(parent, newind, node, PCTRIE_UNSERIALIZED);
+ pctrie_addnode(child, index, pctrie_toleaf(val), PCTRIE_UNSERIALIZED);
+ pctrie_addnode(child, newind, node, PCTRIE_UNSERIALIZED);
/* Synchronize to make the above visible. */
- pctrie_node_store(parentp, parent, PCTRIE_LOCKED);
+ pctrie_node_store(parentp, child, PCTRIE_LOCKED);
}
/*
@@ -531,41 +478,44 @@ pctrie_lookup_unlocked(struct pctrie *ptree, uint64_t index, smr_t smr)
}
/*
- * Returns the last node examined in the search for the index, and updates the
- * search path to that node.
+ * Returns the last node examined in the search for the index, and sets the
+ * parent of that node.
*/
static __always_inline struct pctrie_node *
-_pctrie_iter_lookup_node(struct pctrie_iter *it, uint64_t index, smr_t smr,
- enum pctrie_access access)
+_pctrie_lookup_node(struct pctrie *ptree, struct pctrie_node *node,
+ uint64_t index, struct pctrie_node **parent_out,
+ smr_t smr, enum pctrie_access access)
{
- struct pctrie_node *node;
+ struct pctrie_node *parent;
int slot;
/*
* Climb the search path to find the lowest node from which to start the
* search for a value matching 'index'.
*/
- while (it->top != 0) {
- node = it->path[it->top - 1];
+ while (node != NULL) {
KASSERT(!powerof2(node->pn_popmap),
("%s: freed node in iter path", __func__));
- if (!pctrie_keybarr(node, index, &slot)) {
- node = pctrie_node_load(
- &node->pn_child[slot], smr, access);
+ if (!pctrie_keybarr(node, index, &slot))
break;
- }
- --it->top;
+ node = pctrie_parent(node);
+ }
+
+ if (node == NULL) {
+ parent = NULL;
+ node = pctrie_root_load(ptree, smr, access);
+ } else {
+ parent = node;
+ node = pctrie_node_load(&node->pn_child[slot], smr, access);
}
- if (it->top == 0)
- node = pctrie_root_load(it->ptree, smr, access);
/* Seek a node that matches index. */
while (!pctrie_isleaf(node) && !pctrie_keybarr(node, index, &slot)) {
- KASSERT(it->top < nitems(it->path),
- ("%s: path overflow in trie %p", __func__, it->ptree));
- it->path[it->top++] = node;
+ parent = node;
node = pctrie_node_load(&node->pn_child[slot], smr, access);
}
+ if (parent_out != NULL)
+ *parent_out = parent;
return (node);
}
@@ -579,7 +529,8 @@ _pctrie_iter_lookup(struct pctrie_iter *it, uint64_t index, smr_t smr,
struct pctrie_node *node;
it->index = index;
- node = _pctrie_iter_lookup_node(it, index, smr, access);
+ node = _pctrie_lookup_node(it->ptree, it->node, index, &it->node,
+ smr, access);
return (pctrie_match_value(node, index));
}
@@ -603,13 +554,14 @@ pctrie_iter_insert_lookup(struct pctrie_iter *it, uint64_t *val)
struct pctrie_node *node;
it->index = *val;
- node = _pctrie_iter_lookup_node(it, *val, NULL, PCTRIE_LOCKED);
+ node = _pctrie_lookup_node(it->ptree, it->node, *val, &it->node,
+ NULL, PCTRIE_LOCKED);
if (node == PCTRIE_NULL) {
- if (it->top == 0)
+ if (it->node == NULL)
pctrie_node_store(pctrie_root(it->ptree),
pctrie_toleaf(val), PCTRIE_LOCKED);
else
- pctrie_addnode(it->path[it->top - 1], it->index,
+ pctrie_addnode(it->node, it->index,
pctrie_toleaf(val), PCTRIE_LOCKED);
return (NULL);
}
@@ -622,10 +574,7 @@ pctrie_iter_insert_lookup(struct pctrie_iter *it, uint64_t *val)
* children 'node' and 'val'. Return the place that points to 'node'
* now, and will point to to the new branching node later.
*/
- if (it->top == 0)
- return (pctrie_root(it->ptree));
- node = it->path[it->top - 1];
- return (&node->pn_child[pctrie_slot(node, it->index)]);
+ return (pctrie_child(it->ptree, it->node, it->index));
}
/*
@@ -678,122 +627,21 @@ pctrie_iter_prev(struct pctrie_iter *it)
return (_pctrie_iter_stride(it, -1, NULL, PCTRIE_LOCKED));
}
-/*
- * Returns the value with the least index that is greater than or equal to the
- * specified index, or NULL if there are no such values.
- *
- * Requires that access be externally synchronized by a lock.
- */
-static __inline uint64_t *
-pctrie_lookup_ge_node(struct pctrie_node *node, uint64_t index)
-{
- struct pctrie_node *succ;
- uint64_t *m;
- int slot;
-
- /*
- * Descend the trie as if performing an ordinary lookup for the
- * specified value. However, unlike an ordinary lookup, as we descend
- * the trie, we use "succ" to remember the last branching-off point,
- * that is, the interior node under which the least value that is both
- * outside our current path down the trie and greater than the specified
- * index resides. (The node's popmap makes it fast and easy to
- * recognize a branching-off point.) If our ordinary lookup fails to
- * yield a value that is greater than or equal to the specified index,
- * then we will exit this loop and perform a lookup starting from
- * "succ". If "succ" is not NULL, then that lookup is guaranteed to
- * succeed.
- */
- succ = NULL;
- for (;;) {
- if (pctrie_isleaf(node)) {
- if ((m = pctrie_toval(node)) != NULL && *m >= index)
- return (m);
- break;
- }
- if (pctrie_keybarr(node, index, &slot)) {
- /*
- * If all values in this subtree are > index, then the
- * least value in this subtree is the answer.
- */
- if (node->pn_owner > index)
- succ = node;
- break;
- }
-
- /*
- * Just in case the next search step leads to a subtree of all
- * values < index, check popmap to see if a next bigger step, to
- * a subtree of all pages with values > index, is available. If
- * so, remember to restart the search here.
- */
- if ((node->pn_popmap >> slot) > 1)
- succ = node;
- node = pctrie_node_load(&node->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
-
- /*
- * Restart the search from the last place visited in the subtree that
- * included some values > index, if there was such a place.
- */
- if (succ == NULL)
- return (NULL);
- if (succ != node) {
- /*
- * Take a step to the next bigger sibling of the node chosen
- * last time. In that subtree, all values > index.
- */
- slot = pctrie_slot(succ, index) + 1;
- KASSERT((succ->pn_popmap >> slot) != 0,
- ("%s: no popmap siblings past slot %d in node %p",
- __func__, slot, succ));
- slot += ffs(succ->pn_popmap >> slot) - 1;
- succ = pctrie_node_load(&succ->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
-
- /*
- * Find the value in the subtree rooted at "succ" with the least index.
- */
- while (!pctrie_isleaf(succ)) {
- KASSERT(succ->pn_popmap != 0,
- ("%s: no popmap children in node %p", __func__, succ));
- slot = ffs(succ->pn_popmap) - 1;
- succ = pctrie_node_load(&succ->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
- return (pctrie_toval(succ));
-}
-
-uint64_t *
-pctrie_lookup_ge(struct pctrie *ptree, uint64_t index)
-{
- return (pctrie_lookup_ge_node(
- pctrie_root_load(ptree, NULL, PCTRIE_LOCKED), index));
-}
-
-uint64_t *
-pctrie_subtree_lookup_gt(struct pctrie_node *node, uint64_t index)
-{
- if (node == NULL || index + 1 == 0)
- return (NULL);
- return (pctrie_lookup_ge_node(node, index + 1));
-}
-
/*
* Find first leaf >= index, and fill iter with the path to the parent of that
* leaf. Return NULL if there is no such leaf less than limit.
*/
-uint64_t *
-pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index)
+static __inline uint64_t *
+_pctrie_lookup_ge(struct pctrie *ptree, struct pctrie_node *node,
+ uint64_t index, struct pctrie_node **parent_out, uint64_t limit)
{
- struct pctrie_node *node;
+ struct pctrie_node *parent;
uint64_t *m;
int slot;
/* Seek a node that matches index. */
- node = _pctrie_iter_lookup_node(it, index, NULL, PCTRIE_LOCKED);
+ node = _pctrie_lookup_node(ptree, node, index, &parent,
+ NULL, PCTRIE_LOCKED);
/*
* If no such node was found, and instead this path leads only to nodes
@@ -801,36 +649,58 @@ pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index)
*/
if (node == PCTRIE_NULL || *pctrie_toval(node) < index) {
/* Climb the path to find a node with a descendant > index. */
- while (it->top != 0) {
- node = it->path[it->top - 1];
+ for (node = parent; node != NULL; node = pctrie_parent(node)) {
slot = pctrie_slot(node, index) + 1;
if ((node->pn_popmap >> slot) != 0)
break;
- --it->top;
}
- if (it->top == 0)
+ if (node == NULL) {
+ if (parent_out != NULL)
+ *parent_out = NULL;
return (NULL);
+ }
/* Step to the least child with a descendant > index. */
slot += ffs(node->pn_popmap >> slot) - 1;
+ parent = node;
node = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
/* Descend to the least leaf of the subtrie. */
while (!pctrie_isleaf(node)) {
- if (it->limit != 0 && node->pn_owner >= it->limit)
+ if (limit != 0 && node->pn_owner >= limit)
return (NULL);
slot = ffs(node->pn_popmap) - 1;
- KASSERT(it->top < nitems(it->path),
- ("%s: path overflow in trie %p", __func__, it->ptree));
- it->path[it->top++] = node;
+ parent = node;
node = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
+ if (parent_out != NULL)
+ *parent_out = parent;
m = pctrie_toval(node);
- if (it->limit != 0 && *m >= it->limit)
+ if (limit != 0 && *m >= limit)
return (NULL);
- it->index = *m;
+ return (m);
+}
+
+uint64_t *
+pctrie_lookup_ge(struct pctrie *ptree, uint64_t index)
+{
+ return (_pctrie_lookup_ge(ptree, NULL, index, NULL, 0));
+}
+
+/*
+ * Find first leaf >= index, and fill iter with the path to the parent of that
+ * leaf. Return NULL if there is no such leaf less than limit.
+ */
+uint64_t *
+pctrie_iter_lookup_ge(struct pctrie_iter *it, uint64_t index)
+{
+ uint64_t *m;
+
+ m = _pctrie_lookup_ge(it->ptree, it->node, index, &it->node, it->limit);
+ if (m != NULL)
+ it->index = *m;
return (m);
}
@@ -851,91 +721,76 @@ pctrie_iter_jump_ge(struct pctrie_iter *it, int64_t jump)
return (pctrie_iter_lookup_ge(it, index));
}
-#ifdef INVARIANTS
-void
-pctrie_subtree_lookup_gt_assert(struct pctrie_node *node, uint64_t index,
- struct pctrie *ptree, uint64_t *res)
-{
- uint64_t *expected;
-
- if (index + 1 == 0)
- expected = NULL;
- else
- expected = pctrie_lookup_ge(ptree, index + 1);
- KASSERT(res == expected,
- ("pctrie subtree lookup gt result different from root lookup: "
- "ptree %p, index %ju, subtree %p, found %p, expected %p", ptree,
- (uintmax_t)index, node, res, expected));
-}
-#endif
-
/*
- * Returns the value with the greatest index that is less than or equal to the
- * specified index, or NULL if there are no such values.
- *
- * Requires that access be externally synchronized by a lock.
+ * Find first leaf <= index, and fill iter with the path to the parent of that
+ * leaf. Return NULL if there is no such leaf greater than limit.
*/
static __inline uint64_t *
-pctrie_lookup_le_node(struct pctrie_node *node, uint64_t index)
+_pctrie_lookup_le(struct pctrie *ptree, struct pctrie_node *node,
+ uint64_t index, struct pctrie_node **parent_out, uint64_t limit)
{
- struct pctrie_node *pred;
+ struct pctrie_node *parent;
uint64_t *m;
int slot;
+ /* Seek a node that matches index. */
+ node = _pctrie_lookup_node(ptree, node, index, &parent, NULL,
+ PCTRIE_LOCKED);
+
/*
- * Mirror the implementation of pctrie_lookup_ge_node, described above.
+ * If no such node was found, and instead this path leads only to nodes
+ * > index, back up to find a subtrie with the greatest value < index.
*/
- pred = NULL;
- for (;;) {
- if (pctrie_isleaf(node)) {
- if ((m = pctrie_toval(node)) != NULL && *m <= index)
- return (m);
- break;
+ if (node == PCTRIE_NULL || *pctrie_toval(node) > index) {
+ /* Climb the path to find a node with a descendant < index. */
+ for (node = parent; node != NULL; node = pctrie_parent(node)) {
+ slot = pctrie_slot(node, index);
+ if ((node->pn_popmap & ((1 << slot) - 1)) != 0)
+ break;
}
- if (pctrie_keybarr(node, index, &slot)) {
- if (node->pn_owner < index)
- pred = node;
- break;
+ if (node == NULL) {
+ if (parent_out != NULL)
+ *parent_out = NULL;
+ return (NULL);
}
- if ((node->pn_popmap & ((1 << slot) - 1)) != 0)
- pred = node;
+
+ /* Step to the greatest child with a descendant < index. */
+ slot = ilog2(node->pn_popmap & ((1 << slot) - 1));
+ parent = node;
node = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
- if (pred == NULL)
- return (NULL);
- if (pred != node) {
- slot = pctrie_slot(pred, index);
- KASSERT((pred->pn_popmap & ((1 << slot) - 1)) != 0,
- ("%s: no popmap siblings before slot %d in node %p",
- __func__, slot, pred));
- slot = ilog2(pred->pn_popmap & ((1 << slot) - 1));
- pred = pctrie_node_load(&pred->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
- while (!pctrie_isleaf(pred)) {
- KASSERT(pred->pn_popmap != 0,
- ("%s: no popmap children in node %p", __func__, pred));
- slot = ilog2(pred->pn_popmap);
- pred = pctrie_node_load(&pred->pn_child[slot], NULL,
+ /* Descend to the greatest leaf of the subtrie. */
+ while (!pctrie_isleaf(node)) {
+ if (limit != 0 && limit >= node->pn_owner +
+ ((uint64_t)PCTRIE_COUNT << node->pn_clev) - 1)
+ return (NULL);
+ slot = ilog2(node->pn_popmap);
+ parent = node;
+ node = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
- return (pctrie_toval(pred));
+ if (parent_out != NULL)
+ *parent_out = parent;
+ m = pctrie_toval(node);
+ if (limit != 0 && *m <= limit)
+ return (NULL);
+ return (m);
}
uint64_t *
pctrie_lookup_le(struct pctrie *ptree, uint64_t index)
{
- return (pctrie_lookup_le_node(
- pctrie_root_load(ptree, NULL, PCTRIE_LOCKED), index));
+ return (_pctrie_lookup_le(ptree, NULL, index, NULL, 0));
}
uint64_t *
-pctrie_subtree_lookup_lt(struct pctrie_node *node, uint64_t index)
+pctrie_subtree_lookup_lt(struct pctrie *ptree, struct pctrie_node *node,
+ uint64_t index)
{
- if (node == NULL || index == 0)
+ if (index == 0)
return (NULL);
- return (pctrie_lookup_le_node(node, index - 1));
+ return (_pctrie_lookup_le(ptree, node, index - 1, NULL, 0));
}
/*
@@ -945,50 +800,11 @@ pctrie_subtree_lookup_lt(struct pctrie_node *node, uint64_t index)
uint64_t *
pctrie_iter_lookup_le(struct pctrie_iter *it, uint64_t index)
{
- struct pctrie_node *node;
uint64_t *m;
- int slot;
-
- /* Seek a node that matches index. */
- node = _pctrie_iter_lookup_node(it, index, NULL, PCTRIE_LOCKED);
- /*
- * If no such node was found, and instead this path leads only to nodes
- * > index, back up to find a subtrie with the greatest value < index.
- */
- if (node == PCTRIE_NULL || *pctrie_toval(node) > index) {
- /* Climb the path to find a node with a descendant < index. */
- while (it->top != 0) {
- node = it->path[it->top - 1];
- slot = pctrie_slot(node, index);
- if ((node->pn_popmap & ((1 << slot) - 1)) != 0)
- break;
- --it->top;
- }
- if (it->top == 0)
- return (NULL);
-
- /* Step to the greatest child with a descendant < index. */
- slot = ilog2(node->pn_popmap & ((1 << slot) - 1));
- node = pctrie_node_load(&node->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
- /* Descend to the greatest leaf of the subtrie. */
- while (!pctrie_isleaf(node)) {
- if (it->limit != 0 && it->limit >=
- node->pn_owner + (PCTRIE_COUNT << node->pn_clev) - 1)
- return (NULL);
- slot = ilog2(node->pn_popmap);
- KASSERT(it->top < nitems(it->path),
- ("%s: path overflow in trie %p", __func__, it->ptree));
- it->path[it->top++] = node;
- node = pctrie_node_load(&node->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- }
- m = pctrie_toval(node);
- if (it->limit != 0 && *m <= it->limit)
- return (NULL);
- it->index = *m;
+ m = _pctrie_lookup_le(it->ptree, it->node, index, &it->node, it->limit);
+ if (m != NULL)
+ it->index = *m;
return (m);
}
@@ -1009,35 +825,27 @@ pctrie_iter_jump_le(struct pctrie_iter *it, int64_t jump)
return (pctrie_iter_lookup_le(it, index));
}
-#ifdef INVARIANTS
-void
-pctrie_subtree_lookup_lt_assert(struct pctrie_node *node, uint64_t index,
- struct pctrie *ptree, uint64_t *res)
-{
- uint64_t *expected;
-
- if (index == 0)
- expected = NULL;
- else
- expected = pctrie_lookup_le(ptree, index - 1);
- KASSERT(res == expected,
- ("pctrie subtree lookup lt result different from root lookup: "
- "ptree %p, index %ju, subtree %p, found %p, expected %p", ptree,
- (uintmax_t)index, node, res, expected));
-}
-#endif
-
-static void
-pctrie_remove(struct pctrie *ptree, uint64_t index, struct pctrie_node *parent,
- struct pctrie_node *node, struct pctrie_node **freenode)
+/*
+ * If 'child', a leaf and a child of 'parent', is not NULL and has key 'index',
+ * then remove it from the pctrie and return its value. If doing so produces an
+ * internal node with only one child, purge it from the pctrie and save it in
+ * *freenode for later disposal.
+ */
+static uint64_t *
+pctrie_remove(struct pctrie *ptree, struct pctrie_node *node, uint64_t index,
+ struct pctrie_node *child, struct pctrie_node **freenode)
{
- struct pctrie_node *child;
+ uint64_t *m;
int slot;
+ *freenode = NULL;
+ m = pctrie_match_value(child, index);
+ if (m == NULL)
+ return (m);
if (node == NULL) {
pctrie_node_store(pctrie_root(ptree),
PCTRIE_NULL, PCTRIE_LOCKED);
- return;
+ return (m);
}
slot = pctrie_slot(node, index);
KASSERT((node->pn_popmap & (1 << slot)) != 0,
@@ -1046,28 +854,19 @@ pctrie_remove(struct pctrie *ptree, uint64_t index, struct pctrie_node *parent,
node->pn_popmap ^= 1 << slot;
pctrie_node_store(&node->pn_child[slot], PCTRIE_NULL, PCTRIE_LOCKED);
if (!powerof2(node->pn_popmap))
- return;
+ return (m);
KASSERT(node->pn_popmap != 0, ("%s: bad popmap all zeroes", __func__));
slot = ffs(node->pn_popmap) - 1;
child = pctrie_node_load(&node->pn_child[slot], NULL, PCTRIE_LOCKED);
KASSERT(child != PCTRIE_NULL,
("%s: bad popmap slot %d in node %p", __func__, slot, node));
- if (parent == NULL)
- pctrie_node_store(pctrie_root(ptree), child, PCTRIE_LOCKED);
- else {
- slot = pctrie_slot(parent, index);
- KASSERT(node ==
- pctrie_node_load(&parent->pn_child[slot], NULL,
- PCTRIE_LOCKED), ("%s: invalid child value", __func__));
- pctrie_node_store(&parent->pn_child[slot], child,
- PCTRIE_LOCKED);
- }
- /*
- * The child is still valid and we can not zero the
- * pointer until all SMR references are gone.
- */
- pctrie_node_put(node);
*freenode = node;
+ node = pctrie_parent(node);
+ if (!pctrie_isleaf(child))
+ pctrie_setparent(child, node);
+ pctrie_node_store(pctrie_child(ptree, node, index), child,
+ PCTRIE_LOCKED);
+ return (m);
}
/*
@@ -1078,24 +877,18 @@ uint64_t *
pctrie_remove_lookup(struct pctrie *ptree, uint64_t index,
struct pctrie_node **freenode)
{
- struct pctrie_node *child, *node, *parent;
- uint64_t *m;
+ struct pctrie_node *child, *node;
int slot;
- DEBUG_POISON_POINTER(parent);
- *freenode = node = NULL;
+ node = NULL;
child = pctrie_root_load(ptree, NULL, PCTRIE_LOCKED);
while (!pctrie_isleaf(child)) {
- parent = node;
node = child;
slot = pctrie_slot(node, index);
child = pctrie_node_load(&node->pn_child[slot], NULL,
PCTRIE_LOCKED);
}
- m = pctrie_match_value(child, index);
- if (m != NULL)
- pctrie_remove(ptree, index, parent, node, freenode);
- return (m);
+ return (pctrie_remove(ptree, node, index, child, freenode));
}
/*
@@ -1105,27 +898,14 @@ pctrie_remove_lookup(struct pctrie *ptree, uint64_t index,
uint64_t *
pctrie_iter_remove(struct pctrie_iter *it, struct pctrie_node **freenode)
{
- struct pctrie_node *child, *node, *parent;
+ struct pctrie_node *child;
uint64_t *m;
- int slot;
- DEBUG_POISON_POINTER(parent);
- *freenode = NULL;
- if (it->top >= 1) {
- parent = (it->top >= 2) ? it->path[it->top - 2] : NULL;
- node = it->path[it->top - 1];
- slot = pctrie_slot(node, it->index);
- child = pctrie_node_load(&node->pn_child[slot], NULL,
- PCTRIE_LOCKED);
- } else {
- node = NULL;
- child = pctrie_root_load(it->ptree, NULL, PCTRIE_LOCKED);
- }
- m = pctrie_match_value(child, it->index);
- if (m != NULL)
- pctrie_remove(it->ptree, it->index, parent, node, freenode);
+ child = pctrie_node_load(pctrie_child(it->ptree, it->node, it->index),
+ NULL, PCTRIE_LOCKED);
+ m = pctrie_remove(it->ptree, it->node, it->index, child, freenode);
if (*freenode != NULL)
- --it->top;
+ it->node = pctrie_parent(it->node);
return (m);
}
@@ -1137,25 +917,16 @@ uint64_t *
pctrie_iter_value(struct pctrie_iter *it)
{
struct pctrie_node *node;
- int slot;
- if (it->top == 0)
- node = pctrie_root_load(it->ptree, NULL,
- PCTRIE_LOCKED);
- else {
- node = it->path[it->top - 1];
- slot = pctrie_slot(node, it->index);
*** 319 LINES SKIPPED ***