From 682f23e7bb4a52bedf46eff5c4859e1308eda124 Mon Sep 17 00:00:00 2001 From: Michał Cichoń Date: Tue, 25 Aug 2015 19:56:24 +0200 Subject: Update build ref --- libcurl/src/lib/splay.c | 288 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 288 insertions(+) create mode 100644 libcurl/src/lib/splay.c (limited to 'libcurl/src/lib/splay.c') diff --git a/libcurl/src/lib/splay.c b/libcurl/src/lib/splay.c new file mode 100644 index 0000000..6f8227e --- /dev/null +++ b/libcurl/src/lib/splay.c @@ -0,0 +1,288 @@ +/*************************************************************************** + * _ _ ____ _ + * Project ___| | | | _ \| | + * / __| | | | |_) | | + * | (__| |_| | _ <| |___ + * \___|\___/|_| \_\_____| + * + * Copyright (C) 1997 - 2015, Daniel Stenberg, , et al. + * + * This software is licensed as described in the file COPYING, which + * you should have received as part of this distribution. The terms + * are also available at http://curl.haxx.se/docs/copyright.html. + * + * You may opt to use, copy, modify, merge, publish, distribute and/or sell + * copies of the Software, and permit persons to whom the Software is + * furnished to do so, under the terms of the COPYING file. + * + * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY + * KIND, either express or implied. + * + ***************************************************************************/ + +#include "curl_setup.h" + +#include "splay.h" + +/* + * This macro compares two node keys i and j and returns: + * + * negative value: when i is smaller than j + * zero : when i is equal to j + * positive when : when i is larger than j + */ +#define compare(i,j) Curl_splaycomparekeys((i),(j)) + +/* + * Splay using the key i (which may or may not be in the tree.) The starting + * root is t. + */ +CURL_STATIC struct Curl_tree *Curl_splay(struct timeval i, + struct Curl_tree *t) +{ + struct Curl_tree N, *l, *r, *y; + long comp; + + if(t == NULL) + return t; + N.smaller = N.larger = NULL; + l = r = &N; + + for(;;) { + comp = compare(i, t->key); + if(comp < 0) { + if(t->smaller == NULL) + break; + if(compare(i, t->smaller->key) < 0) { + y = t->smaller; /* rotate smaller */ + t->smaller = y->larger; + y->larger = t; + t = y; + if(t->smaller == NULL) + break; + } + r->smaller = t; /* link smaller */ + r = t; + t = t->smaller; + } + else if(comp > 0) { + if(t->larger == NULL) + break; + if(compare(i, t->larger->key) > 0) { + y = t->larger; /* rotate larger */ + t->larger = y->smaller; + y->smaller = t; + t = y; + if(t->larger == NULL) + break; + } + l->larger = t; /* link larger */ + l = t; + t = t->larger; + } + else + break; + } + + l->larger = t->smaller; /* assemble */ + r->smaller = t->larger; + t->smaller = N.larger; + t->larger = N.smaller; + + return t; +} + +/* Insert key i into the tree t. Return a pointer to the resulting tree or + * NULL if something went wrong. + * + * @unittest: 1309 + */ +CURL_STATIC struct Curl_tree *Curl_splayinsert(struct timeval i, + struct Curl_tree *t, + struct Curl_tree *node) +{ + static const struct timeval KEY_NOTUSED = {-1, -1}; /* will *NEVER* appear */ + + if(node == NULL) + return t; + + if(t != NULL) { + t = Curl_splay(i, t); + if(compare(i, t->key)==0) { + /* There already exists a node in the tree with the very same key. Build + a linked list of nodes. We make the new 'node' struct the new master + node and make the previous node the first one in the 'same' list. */ + + node->same = t; + node->key = i; + node->smaller = t->smaller; + node->larger = t->larger; + + t->smaller = node; /* in the sub node for this same key, we use the + smaller pointer to point back to the master + node */ + + t->key = KEY_NOTUSED; /* and we set the key in the sub node to NOTUSED + to quickly identify this node as a subnode */ + + return node; /* new root node */ + } + } + + if(t == NULL) { + node->smaller = node->larger = NULL; + } + else if(compare(i, t->key) < 0) { + node->smaller = t->smaller; + node->larger = t; + t->smaller = NULL; + + } + else { + node->larger = t->larger; + node->smaller = t; + t->larger = NULL; + } + node->key = i; + + node->same = NULL; /* no identical node (yet) */ + return node; +} + +/* Finds and deletes the best-fit node from the tree. Return a pointer to the + resulting tree. best-fit means the node with the given or lower key */ +CURL_STATIC struct Curl_tree *Curl_splaygetbest(struct timeval i, + struct Curl_tree *t, + struct Curl_tree **removed) +{ + struct Curl_tree *x; + + if(!t) { + *removed = NULL; /* none removed since there was no root */ + return NULL; + } + + t = Curl_splay(i, t); + if(compare(i, t->key) < 0) { + /* too big node, try the smaller chain */ + if(t->smaller) + t=Curl_splay(t->smaller->key, t); + else { + /* fail */ + *removed = NULL; + return t; + } + } + + if(compare(i, t->key) >= 0) { /* found it */ + /* FIRST! Check if there is a list with identical keys */ + x = t->same; + if(x) { + /* there is, pick one from the list */ + + /* 'x' is the new root node */ + + x->key = t->key; + x->larger = t->larger; + x->smaller = t->smaller; + + *removed = t; + return x; /* new root */ + } + + if(t->smaller == NULL) { + x = t->larger; + } + else { + x = Curl_splay(i, t->smaller); + x->larger = t->larger; + } + *removed = t; + + return x; + } + else { + *removed = NULL; /* no match */ + return t; /* It wasn't there */ + } +} + + +/* Deletes the very node we point out from the tree if it's there. Stores a + * pointer to the new resulting tree in 'newroot'. + * + * Returns zero on success and non-zero on errors! TODO: document error codes. + * When returning error, it does not touch the 'newroot' pointer. + * + * NOTE: when the last node of the tree is removed, there's no tree left so + * 'newroot' will be made to point to NULL. + * + * @unittest: 1309 + */ +CURL_STATIC int Curl_splayremovebyaddr(struct Curl_tree *t, + struct Curl_tree *removenode, + struct Curl_tree **newroot) +{ + static const struct timeval KEY_NOTUSED = {-1, -1}; /* will *NEVER* appear */ + struct Curl_tree *x; + + if(!t || !removenode) + return 1; + + if(compare(KEY_NOTUSED, removenode->key) == 0) { + /* Key set to NOTUSED means it is a subnode within a 'same' linked list + and thus we can unlink it easily. The 'smaller' link of a subnode + links to the parent node. */ + if(removenode->smaller == NULL) + return 3; + + removenode->smaller->same = removenode->same; + if(removenode->same) + removenode->same->smaller = removenode->smaller; + + /* Ensures that double-remove gets caught. */ + removenode->smaller = NULL; + + /* voila, we're done! */ + *newroot = t; /* return the same root */ + return 0; + } + + t = Curl_splay(removenode->key, t); + + /* First make sure that we got the same root node as the one we want + to remove, as otherwise we might be trying to remove a node that + isn't actually in the tree. + + We cannot just compare the keys here as a double remove in quick + succession of a node with key != KEY_NOTUSED && same != NULL + could return the same key but a different node. */ + if(t != removenode) + return 2; + + /* Check if there is a list with identical sizes, as then we're trying to + remove the root node of a list of nodes with identical keys. */ + x = t->same; + if(x) { + /* 'x' is the new root node, we just make it use the root node's + smaller/larger links */ + + x->key = t->key; + x->larger = t->larger; + x->smaller = t->smaller; + } + else { + /* Remove the root node */ + if(t->smaller == NULL) + x = t->larger; + else { + x = Curl_splay(removenode->key, t->smaller); + x->larger = t->larger; + } + } + + *newroot = x; /* store new root pointer */ + + return 0; +} + -- cgit v1.2.3