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Subject[RFC PATCH 1/3] Weight-balanced tree
Date
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
include/linux/wbtree.h | 55 ++++++++++++++++
lib/Makefile | 3 +
lib/wbtree.c | 170 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 227 insertions(+), 1 deletions(-)
create mode 100644 include/linux/wbtree.h
create mode 100644 lib/wbtree.c
diff --git a/include/linux/wbtree.h b/include/linux/wbtree.h
new file mode 100644
index 0000000..ef70f6f
--- /dev/null
+++ b/include/linux/wbtree.h
@@ -0,0 +1,55 @@
+/*
+ * Weight-balanced binary tree
+ *
+ * The balance of this tree is based on search probability. The
+ * heaviest weighted nodes (the ones we're most likely to hit), are
+ * at the top of each subtree.
+ *
+ * Copywrite (C) 2011 Red Hat, Inc.
+ *
+ * Authors:
+ * Alex Williamson <alex.williamson@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+#ifndef _LINUX_WBTREE_H
+#define _LINUX_WBTREE_H
+
+#include <linux/kernel.h>
+#include <linux/stddef.h>
+
+struct wb_node {
+ struct wb_node *wb_parent;
+ struct wb_node *wb_left;
+ struct wb_node *wb_right;
+ unsigned long wb_weight;
+};
+
+struct wb_root {
+ struct wb_node *wb_node;
+};
+
+#define WB_ROOT (struct wb_root) { NULL, }
+#define wb_entry(ptr, type, member) container_of(ptr, type, member)
+
+extern void wb_rebalance(struct wb_node *node, struct wb_root *root);
+extern void wb_erase(struct wb_node *node, struct wb_root *root);
+extern struct wb_node *wb_first(struct wb_root *root);
+extern struct wb_node *wb_last(struct wb_root *root);
+extern struct wb_node *wb_next(struct wb_node *node);
+extern struct wb_node *wb_prev(struct wb_node *node);
+
+static inline void wb_set_weight(struct wb_node *node, unsigned long weight)
+{
+ node->wb_weight = weight;
+}
+
+static inline void wb_link_node(struct wb_node *node, struct wb_node *parent,
+ struct wb_node **wb_link)
+{
+ node->wb_left = node->wb_right = NULL;
+ node->wb_parent = parent;
+ *wb_link = node;
+}
+#endif /* _LINUX_WBTREE_H */
diff --git a/lib/Makefile b/lib/Makefile
index cbb774f..5c42e63 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -21,7 +21,8 @@ lib-y += kobject.o kref.o klist.o

obj-y += bcd.o div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
bust_spinlocks.o hexdump.o kasprintf.o bitmap.o scatterlist.o \
- string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o
+ string_helpers.o gcd.o lcm.o list_sort.o uuid.o flex_array.o \
+ wbtree.o

ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG
diff --git a/lib/wbtree.c b/lib/wbtree.c
new file mode 100644
index 0000000..54c3817
--- /dev/null
+++ b/lib/wbtree.c
@@ -0,0 +1,170 @@
+/*
+ * Weight-balanced binary tree
+ *
+ * The balance of this tree is based on search probability. The
+ * heaviest weighted nodes (the ones we're most likely to hit), are
+ * at the top of each subtree.
+ *
+ * Copywrite (C) 2011 Red Hat, Inc.
+ *
+ * Authors:
+ * Alex Williamson <alex.williamson@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+#include <linux/wbtree.h>
+#include <linux/module.h>
+
+static void __wb_rotate_left(struct wb_node *node, struct wb_root *root)
+{
+ struct wb_node *right = node->wb_right;
+ struct wb_node *parent = node->wb_parent;
+
+ if ((node->wb_right = right->wb_left))
+ right->wb_left->wb_parent = node;
+ right->wb_left = node;
+
+ right->wb_parent = parent;
+
+ if (parent) {
+ if (node == parent->wb_left)
+ parent->wb_left = right;
+ else
+ parent->wb_right = right;
+ } else
+ root->wb_node = right;
+
+ node->wb_parent = right;
+}
+
+static void __wb_rotate_right(struct wb_node *node, struct wb_root *root)
+{
+ struct wb_node *left = node->wb_left;
+ struct wb_node *parent = node->wb_parent;
+
+ if ((node->wb_left = left->wb_right))
+ left->wb_right->wb_parent = node;
+ left->wb_right = node;
+
+ left->wb_parent = parent;
+
+ if (parent) {
+ if (node == parent->wb_right)
+ parent->wb_right = left;
+ else
+ parent->wb_left = left;
+ } else
+ root->wb_node = left;
+
+ node->wb_parent = left;
+}
+
+void wb_rebalance(struct wb_node *node, struct wb_root *root)
+{
+ while (node->wb_parent && node->wb_parent->wb_weight < node->wb_weight) {
+ if (node == node->wb_parent->wb_left)
+ __wb_rotate_right(node->wb_parent, root);
+ else
+ __wb_rotate_left(node->wb_parent, root);
+ }
+}
+EXPORT_SYMBOL(wb_rebalance);
+
+void wb_erase(struct wb_node *node, struct wb_root *root)
+{
+ while (node->wb_left || node->wb_right) {
+ if (!node->wb_left)
+ __wb_rotate_left(node, root);
+ else if (!node->wb_right)
+ __wb_rotate_right(node, root);
+ else {
+ if (node->wb_left->wb_weight >
+ node->wb_right->wb_weight)
+ __wb_rotate_right(node, root);
+ else
+ __wb_rotate_left(node, root);
+ }
+ }
+
+ if (node->wb_parent) {
+ if (node->wb_parent->wb_left == node)
+ node->wb_parent->wb_left = NULL;
+ else
+ node->wb_parent->wb_right = NULL;
+ } else
+ root->wb_node = NULL;
+}
+EXPORT_SYMBOL(wb_erase);
+
+struct wb_node *wb_first(struct wb_root *root)
+{
+ struct wb_node *node;
+
+ node = root->wb_node;
+ if (!node)
+ return NULL;
+
+ while (node->wb_left)
+ node = node->wb_left;
+
+ return node;
+}
+EXPORT_SYMBOL(wb_first);
+
+struct wb_node *wb_last(struct wb_root *root)
+{
+ struct wb_node *node;
+
+ node = root->wb_node;
+ if (!node)
+ return NULL;
+
+ while (node->wb_right)
+ node = node->wb_right;
+
+ return node;
+}
+EXPORT_SYMBOL(wb_last);
+
+struct wb_node *wb_next(struct wb_node *node)
+{
+ struct wb_node *parent;
+
+ if (node->wb_parent == node)
+ return NULL;
+
+ if (node->wb_right) {
+ node = node->wb_right;
+ while (node->wb_left)
+ node = node->wb_left;
+ return node;
+ }
+
+ while ((parent = node->wb_parent) && node == parent->wb_right)
+ node = parent;
+
+ return parent;
+}
+EXPORT_SYMBOL(wb_next);
+
+struct wb_node *wb_prev(struct wb_node *node)
+{
+ struct wb_node *parent;
+
+ if (node->wb_parent == node)
+ return NULL;
+
+ if (node->wb_left) {
+ node = node->wb_left;
+ while (node->wb_right)
+ node = node->wb_right;
+ return node;
+ }
+
+ while ((parent = node->wb_parent) && node == parent->wb_left)
+ node = parent;
+
+ return parent;
+}
+EXPORT_SYMBOL(wb_prev);


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