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 <wtf/HashTable.h>
22
23#include <mutex>
24#include <wtf/DataLog.h>
25
26namespace WTF {
27
28#if DUMP_HASHTABLE_STATS
29
30std::atomic<unsigned> HashTableStats::numAccesses;
31std::atomic<unsigned> HashTableStats::numRehashes;
32std::atomic<unsigned> HashTableStats::numRemoves;
33std::atomic<unsigned> HashTableStats::numReinserts;
34
35unsigned HashTableStats::numCollisions;
36unsigned HashTableStats::collisionGraph[4096];
37unsigned HashTableStats::maxCollisions;
38
39static Lock hashTableStatsMutex;
40
41void HashTableStats::recordCollisionAtCount(unsigned count)
42{
43 std::lock_guard<Lock> lock(hashTableStatsMutex);
44
45 if (count > maxCollisions)
46 maxCollisions = count;
47 numCollisions++;
48 collisionGraph[count]++;
49}
50
51void HashTableStats::dumpStats()
52{
53 std::lock_guard<Lock> lock(hashTableStatsMutex);
54
55 dataLogF("\nWTF::HashTable statistics\n\n");
56 dataLogF("%u accesses\n", numAccesses.load());
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 (unsigned i = 1; i <= maxCollisions; i++) {
60 dataLogF(" %u lookups with exactly %u 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.load());
63 dataLogF("%d reinserts\n", numReinserts.load());
64}
65
66#endif
67
68} // namespace WTF
69