mirror of
https://github.com/moparisthebest/curl
synced 2024-11-14 05:25:06 -05:00
8ece8177f1
They serve very little purpose and mostly just add noise. Most of them have been around for a very long time. I read them all before removing or rephrasing them. Ref: #3876 Closes #3883
277 lines
7.5 KiB
C
277 lines
7.5 KiB
C
/***************************************************************************
|
|
* _ _ ____ _
|
|
* 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;
|
|
}
|