188 строки
6.7 KiB
C
188 строки
6.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
|
|
/*
|
|
Interval Trees
|
|
(C) 2012 Michel Lespinasse <walken@google.com>
|
|
|
|
|
|
include/linux/interval_tree_generic.h
|
|
*/
|
|
|
|
#include <linux/rbtree_augmented.h>
|
|
|
|
/*
|
|
* Template for implementing interval trees
|
|
*
|
|
* ITSTRUCT: struct type of the interval tree nodes
|
|
* ITRB: name of struct rb_node field within ITSTRUCT
|
|
* ITTYPE: type of the interval endpoints
|
|
* ITSUBTREE: name of ITTYPE field within ITSTRUCT holding last-in-subtree
|
|
* ITSTART(n): start endpoint of ITSTRUCT node n
|
|
* ITLAST(n): last endpoint of ITSTRUCT node n
|
|
* ITSTATIC: 'static' or empty
|
|
* ITPREFIX: prefix to use for the inline tree definitions
|
|
*
|
|
* Note - before using this, please consider if generic version
|
|
* (interval_tree.h) would work for you...
|
|
*/
|
|
|
|
#define INTERVAL_TREE_DEFINE(ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, \
|
|
ITSTART, ITLAST, ITSTATIC, ITPREFIX) \
|
|
\
|
|
/* Callbacks for augmented rbtree insert and remove */ \
|
|
\
|
|
RB_DECLARE_CALLBACKS_MAX(static, ITPREFIX ## _augment, \
|
|
ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, ITLAST) \
|
|
\
|
|
/* Insert / remove interval nodes from the tree */ \
|
|
\
|
|
ITSTATIC void ITPREFIX ## _insert(ITSTRUCT *node, \
|
|
struct rb_root_cached *root) \
|
|
{ \
|
|
struct rb_node **link = &root->rb_root.rb_node, *rb_parent = NULL; \
|
|
ITTYPE start = ITSTART(node), last = ITLAST(node); \
|
|
ITSTRUCT *parent; \
|
|
bool leftmost = true; \
|
|
\
|
|
while (*link) { \
|
|
rb_parent = *link; \
|
|
parent = rb_entry(rb_parent, ITSTRUCT, ITRB); \
|
|
if (parent->ITSUBTREE < last) \
|
|
parent->ITSUBTREE = last; \
|
|
if (start < ITSTART(parent)) \
|
|
link = &parent->ITRB.rb_left; \
|
|
else { \
|
|
link = &parent->ITRB.rb_right; \
|
|
leftmost = false; \
|
|
} \
|
|
} \
|
|
\
|
|
node->ITSUBTREE = last; \
|
|
rb_link_node(&node->ITRB, rb_parent, link); \
|
|
rb_insert_augmented_cached(&node->ITRB, root, \
|
|
leftmost, &ITPREFIX ## _augment); \
|
|
} \
|
|
\
|
|
ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, \
|
|
struct rb_root_cached *root) \
|
|
{ \
|
|
rb_erase_augmented_cached(&node->ITRB, root, &ITPREFIX ## _augment); \
|
|
} \
|
|
\
|
|
/* \
|
|
* Iterate over intervals intersecting [start;last] \
|
|
* \
|
|
* Note that a node's interval intersects [start;last] iff: \
|
|
* Cond1: ITSTART(node) <= last \
|
|
* and \
|
|
* Cond2: start <= ITLAST(node) \
|
|
*/ \
|
|
\
|
|
static ITSTRUCT * \
|
|
ITPREFIX ## _subtree_search(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
|
|
{ \
|
|
while (true) { \
|
|
/* \
|
|
* Loop invariant: start <= node->ITSUBTREE \
|
|
* (Cond2 is satisfied by one of the subtree nodes) \
|
|
*/ \
|
|
if (node->ITRB.rb_left) { \
|
|
ITSTRUCT *left = rb_entry(node->ITRB.rb_left, \
|
|
ITSTRUCT, ITRB); \
|
|
if (start <= left->ITSUBTREE) { \
|
|
/* \
|
|
* Some nodes in left subtree satisfy Cond2. \
|
|
* Iterate to find the leftmost such node N. \
|
|
* If it also satisfies Cond1, that's the \
|
|
* match we are looking for. Otherwise, there \
|
|
* is no matching interval as nodes to the \
|
|
* right of N can't satisfy Cond1 either. \
|
|
*/ \
|
|
node = left; \
|
|
continue; \
|
|
} \
|
|
} \
|
|
if (ITSTART(node) <= last) { /* Cond1 */ \
|
|
if (start <= ITLAST(node)) /* Cond2 */ \
|
|
return node; /* node is leftmost match */ \
|
|
if (node->ITRB.rb_right) { \
|
|
node = rb_entry(node->ITRB.rb_right, \
|
|
ITSTRUCT, ITRB); \
|
|
if (start <= node->ITSUBTREE) \
|
|
continue; \
|
|
} \
|
|
} \
|
|
return NULL; /* No match */ \
|
|
} \
|
|
} \
|
|
\
|
|
ITSTATIC ITSTRUCT * \
|
|
ITPREFIX ## _iter_first(struct rb_root_cached *root, \
|
|
ITTYPE start, ITTYPE last) \
|
|
{ \
|
|
ITSTRUCT *node, *leftmost; \
|
|
\
|
|
if (!root->rb_root.rb_node) \
|
|
return NULL; \
|
|
\
|
|
/* \
|
|
* Fastpath range intersection/overlap between A: [a0, a1] and \
|
|
* B: [b0, b1] is given by: \
|
|
* \
|
|
* a0 <= b1 && b0 <= a1 \
|
|
* \
|
|
* ... where A holds the lock range and B holds the smallest \
|
|
* 'start' and largest 'last' in the tree. For the later, we \
|
|
* rely on the root node, which by augmented interval tree \
|
|
* property, holds the largest value in its last-in-subtree. \
|
|
* This allows mitigating some of the tree walk overhead for \
|
|
* for non-intersecting ranges, maintained and consulted in O(1). \
|
|
*/ \
|
|
node = rb_entry(root->rb_root.rb_node, ITSTRUCT, ITRB); \
|
|
if (node->ITSUBTREE < start) \
|
|
return NULL; \
|
|
\
|
|
leftmost = rb_entry(root->rb_leftmost, ITSTRUCT, ITRB); \
|
|
if (ITSTART(leftmost) > last) \
|
|
return NULL; \
|
|
\
|
|
return ITPREFIX ## _subtree_search(node, start, last); \
|
|
} \
|
|
\
|
|
ITSTATIC ITSTRUCT * \
|
|
ITPREFIX ## _iter_next(ITSTRUCT *node, ITTYPE start, ITTYPE last) \
|
|
{ \
|
|
struct rb_node *rb = node->ITRB.rb_right, *prev; \
|
|
\
|
|
while (true) { \
|
|
/* \
|
|
* Loop invariants: \
|
|
* Cond1: ITSTART(node) <= last \
|
|
* rb == node->ITRB.rb_right \
|
|
* \
|
|
* First, search right subtree if suitable \
|
|
*/ \
|
|
if (rb) { \
|
|
ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB); \
|
|
if (start <= right->ITSUBTREE) \
|
|
return ITPREFIX ## _subtree_search(right, \
|
|
start, last); \
|
|
} \
|
|
\
|
|
/* Move up the tree until we come from a node's left child */ \
|
|
do { \
|
|
rb = rb_parent(&node->ITRB); \
|
|
if (!rb) \
|
|
return NULL; \
|
|
prev = &node->ITRB; \
|
|
node = rb_entry(rb, ITSTRUCT, ITRB); \
|
|
rb = node->ITRB.rb_right; \
|
|
} while (prev == rb); \
|
|
\
|
|
/* Check if the node intersects [start;last] */ \
|
|
if (last < ITSTART(node)) /* !Cond1 */ \
|
|
return NULL; \
|
|
else if (start <= ITLAST(node)) /* Cond2 */ \
|
|
return node; \
|
|
} \
|
|
}
|