| 1 | /* |
| 2 | Copyright (C) 2005 Apple Inc. All rights reserved. |
| 3 | |
| 4 | This library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Library General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2 of the License, or (at your option) any later version. |
| 8 | |
| 9 | This library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Library General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Library General Public License |
| 15 | along with this library; see the file COPYING.LIB. If not, write to |
| 16 | the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| 17 | Boston, MA 02110-1301, USA. |
| 18 | */ |
| 19 | |
| 20 | #include "config.h" |
| 21 | #include "HashTable.h" |
| 22 | |
| 23 | namespace WTF { |
| 24 | |
| 25 | #if DUMP_HASHTABLE_STATS |
| 26 | |
| 27 | int HashTableStats::numAccesses; |
| 28 | int HashTableStats::numCollisions; |
| 29 | int HashTableStats::collisionGraph[4096]; |
| 30 | int HashTableStats::maxCollisions; |
| 31 | int HashTableStats::numRehashes; |
| 32 | int HashTableStats::numRemoves; |
| 33 | int HashTableStats::numReinserts; |
| 34 | |
| 35 | static HashTableStats logger; |
| 36 | |
| 37 | static Mutex& hashTableStatsMutex() |
| 38 | { |
| 39 | AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex); |
| 40 | return mutex; |
| 41 | } |
| 42 | |
| 43 | HashTableStats::~HashTableStats() |
| 44 | { |
| 45 | // Don't lock hashTableStatsMutex here because it can cause deadlocks at shutdown |
| 46 | // if any thread was killed while holding the mutex. |
| 47 | printf("\nWTF::HashTable statistics\n\n"); |
| 48 | printf("%d accesses\n", numAccesses); |
| 49 | printf("%d total collisions, average %.2f probes per access\n", numCollisions, 1.0 * (numAccesses + numCollisions) / numAccesses); |
| 50 | printf("longest collision chain: %d\n", maxCollisions); |
| 51 | for (int i = 1; i <= maxCollisions; i++) { |
| 52 | printf(" %d lookups with exactly %d collisions (%.2f%% , %.2f%% with this many or more)\n", collisionGraph[i], i, 100.0 * (collisionGraph[i] - collisionGraph[i+1]) / numAccesses, 100.0 * collisionGraph[i] / numAccesses); |
| 53 | } |
| 54 | printf("%d rehashes\n", numRehashes); |
| 55 | printf("%d reinserts\n", numReinserts); |
| 56 | } |
| 57 | |
| 58 | void HashTableStats::recordCollisionAtCount(int count) |
| 59 | { |
| 60 | MutexLocker lock(hashTableStatsMutex()); |
| 61 | if (count > maxCollisions) |
| 62 | maxCollisions = count; |
| 63 | numCollisions++; |
| 64 | collisionGraph[count]++; |
| 65 | } |
| 66 | |
| 67 | #endif |
| 68 | |
| 69 | } // namespace WTF |