| /*************************************************************************** |
| * _ _ ____ _ |
| * Project ___| | | | _ \| | |
| * / __| | | | |_) | | |
| * | (__| |_| | _ <| |___ |
| * \___|\___/|_| \_\_____| |
| * |
| * Copyright (C) 1997 - 2019, 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 https://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. |
| */ |
| struct Curl_tree *Curl_splay(struct curltime i, |
| struct Curl_tree *t) |
| { |
| struct Curl_tree N, *l, *r, *y; |
| |
| if(t == NULL) |
| return t; |
| N.smaller = N.larger = NULL; |
| l = r = &N; |
| |
| for(;;) { |
| long 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 curltime i, |
| struct Curl_tree *t, |
| struct Curl_tree *node) |
| { |
| static const struct curltime KEY_NOTUSED = { |
| (time_t)-1, (unsigned int)-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 doubly-linked circular list of nodes. We add the new 'node' struct |
| to the end of this list. */ |
| |
| node->key = KEY_NOTUSED; /* we set the key in the sub node to NOTUSED |
| to quickly identify this node as a subnode */ |
| node->samen = t; |
| node->samep = t->samep; |
| t->samep->samen = node; |
| t->samep = node; |
| |
| return t; /* the root node always stays the same */ |
| } |
| } |
| |
| 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; |
| |
| /* no identical nodes (yet), we are the only one in the list of nodes */ |
| node->samen = node; |
| node->samep = node; |
| return node; |
| } |
| |
| /* Finds and deletes the best-fit node from the tree. Return a pointer to the |
| resulting tree. best-fit means the smallest node if it is not larger than |
| the key */ |
| struct Curl_tree *Curl_splaygetbest(struct curltime i, |
| struct Curl_tree *t, |
| struct Curl_tree **removed) |
| { |
| static struct curltime tv_zero = {0, 0}; |
| struct Curl_tree *x; |
| |
| if(!t) { |
| *removed = NULL; /* none removed since there was no root */ |
| return NULL; |
| } |
| |
| /* find smallest */ |
| t = Curl_splay(tv_zero, t); |
| if(compare(i, t->key) < 0) { |
| /* even the smallest is too big */ |
| *removed = NULL; |
| return t; |
| } |
| |
| /* FIRST! Check if there is a list with identical keys */ |
| x = t->samen; |
| if(x != t) { |
| /* 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; |
| x->samep = t->samep; |
| t->samep->samen = x; |
| |
| *removed = t; |
| return x; /* new root */ |
| } |
| |
| /* we splayed the tree to the smallest element, there is no smaller */ |
| x = t->larger; |
| *removed = t; |
| |
| return x; |
| } |
| |
| |
| /* 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! |
| * 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 const struct curltime KEY_NOTUSED = { |
| (time_t)-1, (unsigned int)-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. */ |
| if(removenode->samen == removenode) |
| /* A non-subnode should never be set to KEY_NOTUSED */ |
| return 3; |
| |
| removenode->samep->samen = removenode->samen; |
| removenode->samen->samep = removenode->samep; |
| |
| /* Ensures that double-remove gets caught. */ |
| removenode->samen = removenode; |
| |
| *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->samen; |
| if(x != t) { |
| /* '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; |
| x->samep = t->samep; |
| t->samep->samen = x; |
| } |
| 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; |
| } |
