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
hashTableStatsMutex()37 static Mutex& hashTableStatsMutex()
38 {
39 AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);
40 return mutex;
41 }
42
~HashTableStats()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
recordCollisionAtCount(int count)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
70