Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 1 | /* xf86drmHash.c -- Small hash table support for integer -> integer mapping |
| 2 | * Created: Sun Apr 18 09:35:45 1999 by faith@precisioninsight.com |
| 3 | * |
| 4 | * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. |
| 5 | * All Rights Reserved. |
| 6 | * |
| 7 | * Permission is hereby granted, free of charge, to any person obtaining a |
| 8 | * copy of this software and associated documentation files (the "Software"), |
| 9 | * to deal in the Software without restriction, including without limitation |
| 10 | * the rights to use, copy, modify, merge, publish, distribute, sublicense, |
| 11 | * and/or sell copies of the Software, and to permit persons to whom the |
| 12 | * Software is furnished to do so, subject to the following conditions: |
| 13 | * |
| 14 | * The above copyright notice and this permission notice (including the next |
| 15 | * paragraph) shall be included in all copies or substantial portions of the |
| 16 | * Software. |
| 17 | * |
| 18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 19 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 20 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 21 | * PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR |
| 22 | * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, |
| 23 | * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
| 24 | * DEALINGS IN THE SOFTWARE. |
| 25 | * |
| 26 | * Authors: Rickard E. (Rik) Faith <faith@valinux.com> |
| 27 | * |
| 28 | * DESCRIPTION |
| 29 | * |
| 30 | * This file contains a straightforward implementation of a fixed-sized |
| 31 | * hash table using self-organizing linked lists [Knuth73, pp. 398-399] for |
| 32 | * collision resolution. There are two potentially interesting things |
| 33 | * about this implementation: |
| 34 | * |
| 35 | * 1) The table is power-of-two sized. Prime sized tables are more |
| 36 | * traditional, but do not have a significant advantage over power-of-two |
| 37 | * sized table, especially when double hashing is not used for collision |
| 38 | * resolution. |
| 39 | * |
| 40 | * 2) The hash computation uses a table of random integers [Hanson97, |
| 41 | * pp. 39-41]. |
| 42 | * |
| 43 | * FUTURE ENHANCEMENTS |
| 44 | * |
| 45 | * With a table size of 512, the current implementation is sufficient for a |
| 46 | * few hundred keys. Since this is well above the expected size of the |
| 47 | * tables for which this implementation was designed, the implementation of |
| 48 | * dynamic hash tables was postponed until the need arises. A common (and |
| 49 | * naive) approach to dynamic hash table implementation simply creates a |
| 50 | * new hash table when necessary, rehashes all the data into the new table, |
| 51 | * and destroys the old table. The approach in [Larson88] is superior in |
| 52 | * two ways: 1) only a portion of the table is expanded when needed, |
| 53 | * distributing the expansion cost over several insertions, and 2) portions |
| 54 | * of the table can be locked, enabling a scalable thread-safe |
| 55 | * implementation. |
| 56 | * |
| 57 | * REFERENCES |
| 58 | * |
| 59 | * [Hanson97] David R. Hanson. C Interfaces and Implementations: |
| 60 | * Techniques for Creating Reusable Software. Reading, Massachusetts: |
| 61 | * Addison-Wesley, 1997. |
| 62 | * |
| 63 | * [Knuth73] Donald E. Knuth. The Art of Computer Programming. Volume 3: |
| 64 | * Sorting and Searching. Reading, Massachusetts: Addison-Wesley, 1973. |
| 65 | * |
| 66 | * [Larson88] Per-Ake Larson. "Dynamic Hash Tables". CACM 31(4), April |
| 67 | * 1988, pp. 446-457. |
| 68 | * |
| 69 | */ |
| 70 | |
| 71 | #include <stdio.h> |
| 72 | #include <stdlib.h> |
| 73 | |
| 74 | #include "xf86drm.h" |
| 75 | #include "xf86drmHash.h" |
| 76 | |
| 77 | #define DIST_LIMIT 10 |
| 78 | static int dist[DIST_LIMIT]; |
| 79 | |
| 80 | static void clear_dist(void) { |
| 81 | int i; |
| 82 | |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 83 | for (i = 0; i < DIST_LIMIT; i++) |
| 84 | dist[i] = 0; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 85 | } |
| 86 | |
| 87 | static int count_entries(HashBucketPtr bucket) |
| 88 | { |
| 89 | int count = 0; |
| 90 | |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 91 | for (; bucket; bucket = bucket->next) |
| 92 | ++count; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 93 | return count; |
| 94 | } |
| 95 | |
| 96 | static void update_dist(int count) |
| 97 | { |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 98 | if (count >= DIST_LIMIT) |
| 99 | ++dist[DIST_LIMIT-1]; |
| 100 | else |
| 101 | ++dist[count]; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 102 | } |
| 103 | |
| 104 | static void compute_dist(HashTablePtr table) |
| 105 | { |
| 106 | int i; |
| 107 | HashBucketPtr bucket; |
| 108 | |
| 109 | printf("Entries = %ld, hits = %ld, partials = %ld, misses = %ld\n", |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 110 | table->entries, table->hits, table->partials, table->misses); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 111 | clear_dist(); |
| 112 | for (i = 0; i < HASH_SIZE; i++) { |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 113 | bucket = table->buckets[i]; |
| 114 | update_dist(count_entries(bucket)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 115 | } |
| 116 | for (i = 0; i < DIST_LIMIT; i++) { |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 117 | if (i != DIST_LIMIT-1) |
| 118 | printf("%5d %10d\n", i, dist[i]); |
| 119 | else |
| 120 | printf("other %10d\n", dist[i]); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 121 | } |
| 122 | } |
| 123 | |
| 124 | static void check_table(HashTablePtr table, |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 125 | unsigned long key, void * value) |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 126 | { |
Emil Velikov | c53da3a | 2015-03-22 19:58:17 +0000 | [diff] [blame] | 127 | void *retval; |
| 128 | int retcode = drmHashLookup(table, key, &retval); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 129 | |
| 130 | switch (retcode) { |
| 131 | case -1: |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 132 | printf("Bad magic = 0x%08lx:" |
| 133 | " key = %lu, expected = %p, returned = %p\n", |
| 134 | table->magic, key, value, retval); |
| 135 | break; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 136 | case 1: |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 137 | printf("Not found: key = %lu, expected = %p, returned = %p\n", |
| 138 | key, value, retval); |
| 139 | break; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 140 | case 0: |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 141 | if (value != retval) |
| 142 | printf("Bad value: key = %lu, expected = %p, returned = %p\n", |
| 143 | key, value, retval); |
| 144 | break; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 145 | default: |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 146 | printf("Bad retcode = %d: key = %lu, expected = %p, returned = %p\n", |
| 147 | retcode, key, value, retval); |
| 148 | break; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 149 | } |
| 150 | } |
| 151 | |
| 152 | int main(void) |
| 153 | { |
Emil Velikov | c53da3a | 2015-03-22 19:58:17 +0000 | [diff] [blame] | 154 | HashTablePtr table; |
| 155 | unsigned long i; |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 156 | |
| 157 | printf("\n***** 256 consecutive integers ****\n"); |
| 158 | table = drmHashCreate(); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 159 | for (i = 0; i < 256; i++) |
| 160 | drmHashInsert(table, i, (void *)(i << 16 | i)); |
| 161 | for (i = 0; i < 256; i++) |
| 162 | check_table(table, i, (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 163 | compute_dist(table); |
| 164 | drmHashDestroy(table); |
| 165 | |
| 166 | printf("\n***** 1024 consecutive integers ****\n"); |
| 167 | table = drmHashCreate(); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 168 | for (i = 0; i < 1024; i++) |
| 169 | drmHashInsert(table, i, (void *)(i << 16 | i)); |
| 170 | for (i = 0; i < 1024; i++) |
| 171 | check_table(table, i, (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 172 | compute_dist(table); |
| 173 | drmHashDestroy(table); |
| 174 | |
| 175 | printf("\n***** 1024 consecutive page addresses (4k pages) ****\n"); |
| 176 | table = drmHashCreate(); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 177 | for (i = 0; i < 1024; i++) |
| 178 | drmHashInsert(table, i*4096, (void *)(i << 16 | i)); |
| 179 | for (i = 0; i < 1024; i++) |
| 180 | check_table(table, i*4096, (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 181 | compute_dist(table); |
| 182 | drmHashDestroy(table); |
| 183 | |
| 184 | printf("\n***** 1024 random integers ****\n"); |
| 185 | table = drmHashCreate(); |
| 186 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 187 | for (i = 0; i < 1024; i++) |
| 188 | drmHashInsert(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 189 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 190 | for (i = 0; i < 1024; i++) |
| 191 | check_table(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 192 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 193 | for (i = 0; i < 1024; i++) |
| 194 | check_table(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 195 | compute_dist(table); |
| 196 | drmHashDestroy(table); |
| 197 | |
| 198 | printf("\n***** 5000 random integers ****\n"); |
| 199 | table = drmHashCreate(); |
| 200 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 201 | for (i = 0; i < 5000; i++) |
| 202 | drmHashInsert(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 203 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 204 | for (i = 0; i < 5000; i++) |
| 205 | check_table(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 206 | srandom(0xbeefbeef); |
Emil Velikov | 4fcb663 | 2015-03-26 23:09:31 +0000 | [diff] [blame^] | 207 | for (i = 0; i < 5000; i++) |
| 208 | check_table(table, random(), (void *)(i << 16 | i)); |
Emil Velikov | 79f9cf3 | 2015-03-22 19:41:12 +0000 | [diff] [blame] | 209 | compute_dist(table); |
| 210 | drmHashDestroy(table); |
| 211 | |
| 212 | return 0; |
| 213 | } |