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
24namespace WTF {
25
26#if DUMP_HASHTABLE_STATS
27
28int HashTableStats::numAccesses;
29int HashTableStats::numCollisions;
30int HashTableStats::collisionGraph[4096];
31int HashTableStats::maxCollisions;
32int HashTableStats::numRehashes;
33int HashTableStats::numRemoves;
34int HashTableStats::numReinserts;
35
36static Mutex& hashTableStatsMutex()
37{
38    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
39    return mutex;
40}
41
42void HashTableStats::recordCollisionAtCount(int count)
43{
44    MutexLocker lock(hashTableStatsMutex());
45    if (count > maxCollisions)
46        maxCollisions = count;
47    numCollisions++;
48    collisionGraph[count]++;
49}
50
51void 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