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 #include "DataLog.h"
23
24 namespace WTF {
25
26 #if DUMP_HASHTABLE_STATS
27
28 int HashTableStats::numAccesses;
29 int HashTableStats::numCollisions;
30 int HashTableStats::collisionGraph[4096];
31 int HashTableStats::maxCollisions;
32 int HashTableStats::numRehashes;
33 int HashTableStats::numRemoves;
34 int HashTableStats::numReinserts;
35
hashTableStatsMutex()36 static Mutex& hashTableStatsMutex()
37 {
38 AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
39 return mutex;
40 }
41
recordCollisionAtCount(int count)42 void HashTableStats::recordCollisionAtCount(int count)
43 {
44 MutexLocker lock(hashTableStatsMutex());
45 if (count > maxCollisions)
46 maxCollisions = count;
47 numCollisions++;
48 collisionGraph[count]++;
49 }
50
dumpStats()51 void HashTableStats::dumpStats()
52 {
53 MutexLocker lock(hashTableStatsMutex());
54
55 dataLogF("\nWTF::HashTable statistics\n\n");
56 dataLogF("%d accesses\n", numAccesses);
57 dataLogF("%d total collisions, average %.2f probes per access\n", numCollisions, 1.0 * (numAccesses + numCollisions) / numAccesses);
58 dataLogF("longest collision chain: %d\n", maxCollisions);
59 for (int i = 1; i <= maxCollisions; i++) {
60 dataLogF(" %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);
61 }
62 dataLogF("%d rehashes\n", numRehashes);
63 dataLogF("%d reinserts\n", numReinserts);
64 }
65
66 #endif
67
68 } // namespace WTF
69