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a1d1f43e6a
curl/lib/splay.c
Yang Tse 59e378f48f remove unnecessary typecasting of malloc()
2008-09-06 05:29:05 +00:00

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11 KiB
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/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1997 - 2008, 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.
*
* $Id$
***************************************************************************/
#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. */
struct Curl_tree *Curl_splayinsert(struct timeval i,
struct Curl_tree *t,
struct Curl_tree *node)
{
static struct timeval KEY_NOTUSED = {-1,-1}; /* key that 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;
}
#if 0
/* Deletes 'i' from the tree if it's there (with an exact match). Returns a
pointer to the resulting tree.
Function not used in libcurl.
*/
struct Curl_tree *Curl_splayremove(struct timeval i,
struct Curl_tree *t,
struct Curl_tree **removed)
{
struct Curl_tree *x;
*removed = NULL; /* default to no removed */
if(t==NULL)
return NULL;
t = Curl_splay(i,t);
if(compare(i, t->key) == 0) { /* found it */
/* FIRST! Check if there is a list with identical sizes */
if((x = t->same) != NULL) {
/* 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
return t; /* It wasn't there */
}
#endif
/* 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.
*/
int Curl_splayremovebyaddr(struct Curl_tree *t,
struct Curl_tree *removenode,
struct Curl_tree **newroot)
{
static struct timeval KEY_NOTUSED = {-1,-1}; /* key that 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;
}
#ifdef CURLDEBUG
void Curl_splayprint(struct Curl_tree * t, int d, char output)
{
struct Curl_tree *node;
int i;
int count;
if(t == NULL)
return;
Curl_splayprint(t->larger, d+1, output);
for (i=0; i<d; i++)
if(output)
printf(" ");
if(output) {
#ifdef TEST_SPLAY
printf("%ld[%d]", (long)t->key.tv_usec, i);
#else
printf("%ld.%ld[%d]", (long)t->key.tv_sec, (long)t->key.tv_usec, i);
#endif
}
for(count=0, node = t->same; node; node = node->same, count++)
;
if(output) {
if(count)
printf(" [%d more]\n", count);
else
printf("\n");
}
Curl_splayprint(t->smaller, d+1, output);
}
#endif
#ifdef TEST_SPLAY
/*#define TEST2 */
#define MAX 50
#define TEST2
/* A sample use of these functions. Start with the empty tree, insert some
stuff into it, and then delete it */
int main(int argc, argv_item_t argv[])
{
struct Curl_tree *root, *t;
void *ptrs[MAX];
int adds=0;
int rc;
static const long sizes[]={
50, 60, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200, 300,
220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120, 200,
300, 220, 80, 90, 50, 100, 60, 200, 120, 300, 400, 200, 256, 122, 60, 120,
200, 300, 220, 80, 90};
int i;
root = NULL; /* the empty tree */
for (i = 0; i < MAX; i++) {
struct timeval key;
ptrs[i] = t = malloc(sizeof(struct Curl_tree));
key.tv_sec = 0;
#ifdef TEST2
key.tv_usec = sizes[i];
#elif defined(TEST1)
key.tv_usec = (541*i)%1023;
#elif defined(TEST3)
key.tv_usec = 100;
#endif
t->payload = (void *)key.tv_usec; /* for simplicity */
if(!t) {
puts("out of memory!");
return 0;
}
root = Curl_splayinsert(key, root, t);
}
#if 0
puts("Result:");
Curl_splayprint(root, 0, 1);
#endif
#if 1
for (i = 0; i < MAX; i++) {
int rem = (i+7)%MAX;
struct Curl_tree *r;
printf("Tree look:\n");
Curl_splayprint(root, 0, 1);
printf("remove pointer %d, payload %ld\n", rem,
(long)((struct Curl_tree *)ptrs[rem])->payload);
rc = Curl_splayremovebyaddr(root, (struct Curl_tree *)ptrs[rem], &root);
if(rc)
/* failed! */
printf("remove %d failed!\n", rem);
}
#endif
return 0;
}
#endif /* TEST_SPLAY */
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