218 lines
7.1 KiB
C
218 lines
7.1 KiB
C
/* xf86drmHash.c -- Small hash table support for integer -> integer mapping
|
|
* Created: Sun Apr 18 09:35:45 1999 by faith@precisioninsight.com
|
|
*
|
|
* Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
|
|
* All Rights Reserved.
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a
|
|
* copy of this software and associated documentation files (the "Software"),
|
|
* to deal in the Software without restriction, including without limitation
|
|
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
|
|
* and/or sell copies of the Software, and to permit persons to whom the
|
|
* Software is furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice (including the next
|
|
* paragraph) shall be included in all copies or substantial portions of the
|
|
* Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
|
|
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
|
|
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
|
|
* DEALINGS IN THE SOFTWARE.
|
|
*
|
|
* Authors: Rickard E. (Rik) Faith <faith@valinux.com>
|
|
*
|
|
* DESCRIPTION
|
|
*
|
|
* This file contains a straightforward implementation of a fixed-sized
|
|
* hash table using self-organizing linked lists [Knuth73, pp. 398-399] for
|
|
* collision resolution. There are two potentially interesting things
|
|
* about this implementation:
|
|
*
|
|
* 1) The table is power-of-two sized. Prime sized tables are more
|
|
* traditional, but do not have a significant advantage over power-of-two
|
|
* sized table, especially when double hashing is not used for collision
|
|
* resolution.
|
|
*
|
|
* 2) The hash computation uses a table of random integers [Hanson97,
|
|
* pp. 39-41].
|
|
*
|
|
* FUTURE ENHANCEMENTS
|
|
*
|
|
* With a table size of 512, the current implementation is sufficient for a
|
|
* few hundred keys. Since this is well above the expected size of the
|
|
* tables for which this implementation was designed, the implementation of
|
|
* dynamic hash tables was postponed until the need arises. A common (and
|
|
* naive) approach to dynamic hash table implementation simply creates a
|
|
* new hash table when necessary, rehashes all the data into the new table,
|
|
* and destroys the old table. The approach in [Larson88] is superior in
|
|
* two ways: 1) only a portion of the table is expanded when needed,
|
|
* distributing the expansion cost over several insertions, and 2) portions
|
|
* of the table can be locked, enabling a scalable thread-safe
|
|
* implementation.
|
|
*
|
|
* REFERENCES
|
|
*
|
|
* [Hanson97] David R. Hanson. C Interfaces and Implementations:
|
|
* Techniques for Creating Reusable Software. Reading, Massachusetts:
|
|
* Addison-Wesley, 1997.
|
|
*
|
|
* [Knuth73] Donald E. Knuth. The Art of Computer Programming. Volume 3:
|
|
* Sorting and Searching. Reading, Massachusetts: Addison-Wesley, 1973.
|
|
*
|
|
* [Larson88] Per-Ake Larson. "Dynamic Hash Tables". CACM 31(4), April
|
|
* 1988, pp. 446-457.
|
|
*
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
#include "xf86drm.h"
|
|
#include "xf86drmHash.h"
|
|
|
|
#define DIST_LIMIT 10
|
|
static int dist[DIST_LIMIT];
|
|
|
|
static void clear_dist(void) {
|
|
int i;
|
|
|
|
for (i = 0; i < DIST_LIMIT; i++)
|
|
dist[i] = 0;
|
|
}
|
|
|
|
static int count_entries(HashBucketPtr bucket)
|
|
{
|
|
int count = 0;
|
|
|
|
for (; bucket; bucket = bucket->next)
|
|
++count;
|
|
return count;
|
|
}
|
|
|
|
static void update_dist(int count)
|
|
{
|
|
if (count >= DIST_LIMIT)
|
|
++dist[DIST_LIMIT-1];
|
|
else
|
|
++dist[count];
|
|
}
|
|
|
|
static void compute_dist(HashTablePtr table)
|
|
{
|
|
int i;
|
|
HashBucketPtr bucket;
|
|
|
|
printf("Entries = %ld, hits = %ld, partials = %ld, misses = %ld\n",
|
|
table->entries, table->hits, table->partials, table->misses);
|
|
clear_dist();
|
|
for (i = 0; i < HASH_SIZE; i++) {
|
|
bucket = table->buckets[i];
|
|
update_dist(count_entries(bucket));
|
|
}
|
|
for (i = 0; i < DIST_LIMIT; i++) {
|
|
if (i != DIST_LIMIT-1)
|
|
printf("%5d %10d\n", i, dist[i]);
|
|
else
|
|
printf("other %10d\n", dist[i]);
|
|
}
|
|
}
|
|
|
|
static int check_table(HashTablePtr table,
|
|
unsigned long key, void * value)
|
|
{
|
|
void *retval;
|
|
int retcode = drmHashLookup(table, key, &retval);
|
|
|
|
switch (retcode) {
|
|
case -1:
|
|
printf("Bad magic = 0x%08lx:"
|
|
" key = %lu, expected = %p, returned = %p\n",
|
|
table->magic, key, value, retval);
|
|
break;
|
|
case 1:
|
|
printf("Not found: key = %lu, expected = %p, returned = %p\n",
|
|
key, value, retval);
|
|
break;
|
|
case 0:
|
|
if (value != retval) {
|
|
printf("Bad value: key = %lu, expected = %p, returned = %p\n",
|
|
key, value, retval);
|
|
retcode = -1;
|
|
}
|
|
break;
|
|
default:
|
|
printf("Bad retcode = %d: key = %lu, expected = %p, returned = %p\n",
|
|
retcode, key, value, retval);
|
|
break;
|
|
}
|
|
return retcode;
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
HashTablePtr table;
|
|
unsigned long i;
|
|
int ret = 0;
|
|
|
|
printf("\n***** 256 consecutive integers ****\n");
|
|
table = drmHashCreate();
|
|
for (i = 0; i < 256; i++)
|
|
drmHashInsert(table, i, (void *)(i << 16 | i));
|
|
for (i = 0; i < 256; i++)
|
|
ret |= check_table(table, i, (void *)(i << 16 | i));
|
|
compute_dist(table);
|
|
drmHashDestroy(table);
|
|
|
|
printf("\n***** 1024 consecutive integers ****\n");
|
|
table = drmHashCreate();
|
|
for (i = 0; i < 1024; i++)
|
|
drmHashInsert(table, i, (void *)(i << 16 | i));
|
|
for (i = 0; i < 1024; i++)
|
|
ret |= check_table(table, i, (void *)(i << 16 | i));
|
|
compute_dist(table);
|
|
drmHashDestroy(table);
|
|
|
|
printf("\n***** 1024 consecutive page addresses (4k pages) ****\n");
|
|
table = drmHashCreate();
|
|
for (i = 0; i < 1024; i++)
|
|
drmHashInsert(table, i*4096, (void *)(i << 16 | i));
|
|
for (i = 0; i < 1024; i++)
|
|
ret |= check_table(table, i*4096, (void *)(i << 16 | i));
|
|
compute_dist(table);
|
|
drmHashDestroy(table);
|
|
|
|
printf("\n***** 1024 random integers ****\n");
|
|
table = drmHashCreate();
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 1024; i++)
|
|
drmHashInsert(table, random(), (void *)(i << 16 | i));
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 1024; i++)
|
|
ret |= check_table(table, random(), (void *)(i << 16 | i));
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 1024; i++)
|
|
ret |= check_table(table, random(), (void *)(i << 16 | i));
|
|
compute_dist(table);
|
|
drmHashDestroy(table);
|
|
|
|
printf("\n***** 5000 random integers ****\n");
|
|
table = drmHashCreate();
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 5000; i++)
|
|
drmHashInsert(table, random(), (void *)(i << 16 | i));
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 5000; i++)
|
|
ret |= check_table(table, random(), (void *)(i << 16 | i));
|
|
srandom(0xbeefbeef);
|
|
for (i = 0; i < 5000; i++)
|
|
ret |= check_table(table, random(), (void *)(i << 16 | i));
|
|
compute_dist(table);
|
|
drmHashDestroy(table);
|
|
|
|
return ret;
|
|
}
|