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 

    37 static Mutex& hashTableStatsMutex()

    38 {

    39     AtomicallyInitializedStatic(Mutex&, mutex = *new Mutex);

    40     return mutex;

    41 }

    42 

    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 

    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