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/*
Copyright (C) 2005 Apple Inc. All rights reserved.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "wtf/HashTable.h"
#if DUMP_HASHTABLE_STATS
#include "wtf/DataLog.h"
#include "wtf/ThreadingPrimitives.h"
namespace WTF {
static Mutex& hashTableStatsMutex() {
DEFINE_THREAD_SAFE_STATIC_LOCAL(Mutex, mutex, new Mutex);
return mutex;
}
HashTableStats& HashTableStats::instance() {
DEFINE_THREAD_SAFE_STATIC_LOCAL(HashTableStats, stats, new HashTableStats);
return stats;
}
void HashTableStats::copy(const HashTableStats* other) {
numAccesses = other->numAccesses;
numRehashes = other->numRehashes;
numRemoves = other->numRemoves;
numReinserts = other->numReinserts;
maxCollisions = other->maxCollisions;
numCollisions = other->numCollisions;
memcpy(collisionGraph, other->collisionGraph, sizeof(collisionGraph));
}
void HashTableStats::recordCollisionAtCount(int count) {
// The global hash table singleton needs to be atomically updated.
bool isGlobalSingleton = this == &instance();
if (isGlobalSingleton)
hashTableStatsMutex().lock();
if (count > maxCollisions)
maxCollisions = count;
numCollisions++;
collisionGraph[count]++;
if (isGlobalSingleton)
hashTableStatsMutex().unlock();
}
void HashTableStats::dumpStats() {
// Lock the global hash table singleton while dumping.
bool isGlobalSingleton = this == &instance();
if (isGlobalSingleton)
hashTableStatsMutex().lock();
dataLogF("\nWTF::HashTable statistics\n\n");
dataLogF("%d accesses\n", numAccesses);
dataLogF("%d total collisions, average %.2f probes per access\n",
numCollisions, 1.0 * (numAccesses + numCollisions) / numAccesses);
dataLogF("longest collision chain: %d\n", maxCollisions);
for (int i = 1; i <= maxCollisions; i++) {
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);
}
dataLogF("%d rehashes\n", numRehashes);
dataLogF("%d reinserts\n", numReinserts);
if (isGlobalSingleton)
hashTableStatsMutex().unlock();
}
} // namespace WTF
#endif
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