/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 1997 - 2011, Daniel Stenberg, <daniel@haxx.se>, 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 "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. */ 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 */ struct Curl_tree *Curl_splayinsert(struct timeval i, struct Curl_tree *t, struct Curl_tree *node) { static 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 */ 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 */ int Curl_splayremovebyaddr(struct Curl_tree *t, struct Curl_tree *removenode, struct Curl_tree **newroot) { static 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; }