initial commit

third_party/libhv/base/rbtree.h

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+/*
+  Red Black Trees
+  (C) 1999  Andrea Arcangeli <andrea@suse.de>
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+  linux/include/linux/rbtree.h
+
+  To use rbtrees you'll have to implement your own insert and search cores.
+  This will avoid us to use callbacks and to drop drammatically performances.
+  I know it's not the cleaner way,  but in C (not in C++) to get
+  performances and genericity...
+
+  Some example of insert and search follows here. The search is a plain
+  normal search over an ordered tree. The insert instead must be implemented
+  in two steps: First, the code must insert the element in order as a red leaf
+  in the tree, and then the support library function rb_insert_color() must
+  be called. Such function will do the not trivial work to rebalance the
+  rbtree, if necessary.
+
+-----------------------------------------------------------------------
+static inline struct page * rb_search_page_cache(struct inode * inode,
+                         unsigned long offset)
+{
+    struct rb_node * n = inode->i_rb_page_cache.rb_node;
+    struct page * page;
+
+    while (n)
+    {
+        page = rb_entry(n, struct page, rb_page_cache);
+
+        if (offset < page->offset)
+            n = n->rb_left;
+        else if (offset > page->offset)
+            n = n->rb_right;
+        else
+            return page;
+    }
+    return NULL;
+}
+
+static inline struct page * __rb_insert_page_cache(struct inode * inode,
+                           unsigned long offset,
+                           struct rb_node * node)
+{
+    struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
+    struct rb_node * parent = NULL;
+    struct page * page;
+
+    while (*p)
+    {
+        parent = *p;
+        page = rb_entry(parent, struct page, rb_page_cache);
+
+        if (offset < page->offset)
+            p = &(*p)->rb_left;
+        else if (offset > page->offset)
+            p = &(*p)->rb_right;
+        else
+            return page;
+    }
+
+    rb_link_node(node, parent, p);
+
+    return NULL;
+}
+
+static inline struct page * rb_insert_page_cache(struct inode * inode,
+                         unsigned long offset,
+                         struct rb_node * node)
+{
+    struct page * ret;
+    if ((ret = __rb_insert_page_cache(inode, offset, node)))
+        goto out;
+    rb_insert_color(node, &inode->i_rb_page_cache);
+ out:
+    return ret;
+}
+-----------------------------------------------------------------------
+*/
+
+#ifndef _LINUX_RBTREE_H
+#define _LINUX_RBTREE_H
+
+struct rb_node
+{
+    struct rb_node *rb_parent;
+    struct rb_node *rb_right;
+    struct rb_node *rb_left;
+    char            rb_color;
+#define RB_RED      0
+#define RB_BLACK    1
+};
+
+struct rb_root
+{
+    struct rb_node *rb_node;
+};
+
+#define RB_ROOT (struct rb_root){ (struct rb_node *)0, }
+#define rb_entry(ptr, type, member) \
+    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+void rb_insert_color(struct rb_node *node, struct rb_root *root);
+void rb_erase(struct rb_node *node, struct rb_root *root);
+
+/* Find logical next and previous nodes in a tree */
+struct rb_node *rb_next(struct rb_node *);
+struct rb_node *rb_prev(struct rb_node *);
+struct rb_node *rb_first(struct rb_root *);
+struct rb_node *rb_last(struct rb_root *);
+
+/* Fast replacement of a single node without remove/rebalance/add/rebalance */
+void rb_replace_node(struct rb_node *victim, struct rb_node *newnode,
+                struct rb_root *root);
+
+#ifdef __cplusplus
+}
+#endif
+
+static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
+                struct rb_node **link)
+{
+    node->rb_parent = parent;
+    node->rb_color = RB_RED;
+    node->rb_left = node->rb_right = (struct rb_node *)0;
+    *link = node;
+}
+
+#endif  /* _LINUX_RBTREE_H */