diff options
Diffstat (limited to 'tests/auto/corelib/tools/qcache/tst_qcache.cpp')
-rw-r--r-- | tests/auto/corelib/tools/qcache/tst_qcache.cpp | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/tests/auto/corelib/tools/qcache/tst_qcache.cpp b/tests/auto/corelib/tools/qcache/tst_qcache.cpp index eb024e8f9e..d53e8bf880 100644 --- a/tests/auto/corelib/tools/qcache/tst_qcache.cpp +++ b/tests/auto/corelib/tools/qcache/tst_qcache.cpp @@ -50,6 +50,7 @@ private slots: void largeCache(); void internalChainOrderAfterEntryUpdate(); void emplaceLowerCost(); + void trimWithMovingAcrossSpans(); }; @@ -446,5 +447,70 @@ void tst_QCache::emplaceLowerCost() QVERIFY(cache.isEmpty()); } +struct TrivialHashType { + int i = -1; + size_t hash = 0; + + TrivialHashType(int i, size_t hash) : i(i), hash(hash) {} + TrivialHashType(const TrivialHashType &o) noexcept = default; + TrivialHashType &operator=(const TrivialHashType &o) noexcept = default; + TrivialHashType(TrivialHashType &&o) noexcept : i(o.i), hash(o.hash) { + o.i = -1; + o.hash = 0; + } + TrivialHashType &operator=(TrivialHashType &&o) noexcept { + i = o.i; + hash = o.hash; + o.i = -1; + o.hash = 0; + return *this; + } + + + friend bool operator==(const TrivialHashType &lhs, const TrivialHashType &rhs) + { + return lhs.i == rhs.i; + } +}; +quint64 qHash(TrivialHashType t, size_t seed = 0) +{ + return t.hash; +} + +// During trim(), if the Node we have a pointer to in the function is moved +// to another span in the hash table, our pointer would end up pointing to +// garbage memory. Test that this no longer happens +void tst_QCache::trimWithMovingAcrossSpans() +{ + qsizetype numBuckets = [](){ + QHash<int, int> h; + h.reserve(1); + // Beholden to QHash internals: + return h.capacity() << 1; + }(); + + QCache<TrivialHashType, int> cache; + cache.setMaxCost(1000); + + auto lastBucketInSpan = size_t(numBuckets - 1); + // If this fails then the test is no longer valid + QCOMPARE(QHashPrivate::GrowthPolicy::bucketForHash(numBuckets, lastBucketInSpan), + lastBucketInSpan); + + // Pad some space so we have two spans: + for (int i = 2; i < numBuckets; ++i) + cache.insert({i, 0}, nullptr); + + // These two are vying for the last bucket in the first span, + // when '0' is deleted, '1' is moved across the span boundary, + // invalidating any pointer to its Node. + cache.insert({0, lastBucketInSpan}, nullptr); + cache.insert({1, lastBucketInSpan}, nullptr); + + QCOMPARE(cache.size(), numBuckets); + cache.setMaxCost(0); + QCOMPARE(cache.size(), 0); +} + QTEST_APPLESS_MAIN(tst_QCache) #include "tst_qcache.moc" |