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
23namespace WTF {
24
25#if DUMP_HASHTABLE_STATS
26
27int HashTableStats::numAccesses;
28int HashTableStats::numCollisions;
29int HashTableStats::collisionGraph[4096];
30int HashTableStats::maxCollisions;
31int HashTableStats::numRehashes;
32int HashTableStats::numRemoves;
33int HashTableStats::numReinserts;
34
35static HashTableStats logger;
36
37static Mutex& hashTableStatsMutex()
38{
39    AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
40    return mutex;
41}
42
43HashTableStats::~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
58void 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
70