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Q[Multi]Hash: fix squeeze()

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When calling QHash::reserve(), or when creating the
internal QHashPrivate::Data structure, the value 0
for the size parameter is reserved for performing
the squeeze operation.

However commit 8a984ab772
broke it, by using the 0 value in QHashPrivate::Data
constructors as a mark that no resizing needs to be done.

This patch reverts the problematic commit (also applying
some later fixes to the code), and adds the missing
tests for Q[Multi]Hash::squeeze().

Pick-to: 6.3 6.2
Change-Id: Id644df7b2beb008e6a37b2c89b709adfbd893e25
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Ivan Solovev 2022-04-01 10:37:45 +02:00
parent d11941db41
commit 7c9afa8d00
2 changed files with 123 additions and 16 deletions
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44
src/corelib/tools/qhash.h
View File

@ -565,7 +565,6 @@ struct Data
}
};
Data(size_t reserve = 0)
{
numBuckets = GrowthPolicy::bucketsForCapacity(reserve);
@ -573,25 +572,16 @@ struct Data
spans = new Span[nSpans];
seed = QHashSeed::globalSeed();
}
Data(const Data &other, size_t reserved = 0)
: size(other.size),
numBuckets(other.numBuckets),
seed(other.seed)
{
if (reserved)
numBuckets = GrowthPolicy::bucketsForCapacity(qMax(size, reserved));
bool resized = numBuckets != other.numBuckets;
size_t nSpans = numBuckets >> SpanConstants::SpanShift;
spans = new Span[nSpans];
size_t otherNSpans = other.numBuckets >> SpanConstants::SpanShift;
for (size_t s = 0; s < otherNSpans; ++s) {
void reallocationHelper(const Data &other, size_t nSpans, bool resized)
{
for (size_t s = 0; s < nSpans; ++s) {
const Span &span = other.spans[s];
for (size_t index = 0; index < SpanConstants::NEntries; ++index) {
if (!span.hasNode(index))
continue;
const Node &n = span.at(index);
auto it = resized ? findBucket(n.key) : Bucket{ spans + s, index };
auto it = resized ? findBucket(n.key) : Bucket { spans + s, index };
Q_ASSERT(it.isUnused());
Node *newNode = it.insert();
new (newNode) Node(n);
@ -599,7 +589,31 @@ struct Data
}
}
static Data *detached(Data *d, size_t size = 0)
Data(const Data &other) : size(other.size), numBuckets(other.numBuckets), seed(other.seed)
{
size_t nSpans = numBuckets >> SpanConstants::SpanShift;
spans = new Span[nSpans];
reallocationHelper(other, nSpans, false);
}
Data(const Data &other, size_t reserved) : size(other.size), seed(other.seed)
{
numBuckets = GrowthPolicy::bucketsForCapacity(qMax(size, reserved));
size_t nSpans = numBuckets >> SpanConstants::SpanShift;
spans = new Span[nSpans];
size_t otherNSpans = other.numBuckets >> SpanConstants::SpanShift;
reallocationHelper(other, otherNSpans, true);
}
static Data *detached(Data *d)
{
if (!d)
return new Data;
Data *dd = new Data(*d);
if (!d->ref.deref())
delete d;
return dd;
}
static Data *detached(Data *d, size_t size)
{
if (!d)
return new Data(size);

95
tests/auto/corelib/tools/qhash/tst_qhash.cpp
View File

@ -105,6 +105,9 @@ private slots:
void detachAndReferences();
void lookupUsingKeyIterator();
void squeeze();
void squeezeShared();
};
struct IdentityTracker {
@ -2694,7 +2697,7 @@ void tst_QHash::reserveLessThanCurrentAmount()
// Make sure that hash still has all elements
for (int i = 0; i < 1000; ++i)
QCOMPARE(hash.values(i), QList<int>() << i * 10 + 1 << i * 10);
QCOMPARE(hash.values(i), QList<int>({ i * 10 + 1, i * 10 }));
}
}
@ -2774,5 +2777,95 @@ void tst_QHash::lookupUsingKeyIterator()
QVERIFY(!hash[*it].isEmpty());
}
void tst_QHash::squeeze()
{
{
QHash<int, int> hash;
hash.reserve(1000);
for (int i = 0; i < 10; ++i)
hash.insert(i, i * 10);
QVERIFY(hash.isDetached());
const size_t buckets = hash.bucket_count();
const qsizetype size = hash.size();
hash.squeeze();
QVERIFY(hash.bucket_count() < buckets);
QCOMPARE(hash.size(), size);
for (int i = 0; i < size; ++i)
QCOMPARE(hash.value(i), i * 10);
}
{
QMultiHash<int, int> hash;
hash.reserve(1000);
for (int i = 0; i < 10; ++i) {
hash.insert(i, i * 10);
hash.insert(i, i * 10 + 1);
}
QVERIFY(hash.isDetached());
const size_t buckets = hash.bucket_count();
const qsizetype size = hash.size();
hash.squeeze();
QVERIFY(hash.bucket_count() < buckets);
QCOMPARE(hash.size(), size);
for (int i = 0; i < (size / 2); ++i)
QCOMPARE(hash.values(i), QList<int>({ i * 10 + 1, i * 10 }));
}
}
void tst_QHash::squeezeShared()
{
{
QHash<int, int> hash;
hash.reserve(1000);
for (int i = 0; i < 10; ++i)
hash.insert(i, i * 10);
QHash<int, int> other = hash;
// Check that when squeezing a hash with shared d_ptr, the number of
// buckets actually decreases.
QVERIFY(!other.isDetached());
const size_t buckets = other.bucket_count();
const qsizetype size = other.size();
other.squeeze();
QCOMPARE(hash.bucket_count(), buckets);
QVERIFY(other.bucket_count() < buckets);
QCOMPARE(other.size(), size);
for (int i = 0; i < size; ++i)
QCOMPARE(other.value(i), i * 10);
}
{
QMultiHash<int, int> hash;
hash.reserve(1000);
for (int i = 0; i < 10; ++i) {
hash.insert(i, i * 10);
hash.insert(i, i * 10 + 1);
}
QMultiHash<int, int> other = hash;
// Check that when squeezing a hash with shared d_ptr, the number of
// buckets actually decreases.
QVERIFY(!other.isDetached());
const size_t buckets = other.bucket_count();
const qsizetype size = other.size();
other.squeeze();
QCOMPARE(hash.bucket_count(), buckets);
QVERIFY(other.bucket_count() < buckets);
QCOMPARE(other.size(), size);
for (int i = 0; i < (size / 2); ++i)
QCOMPARE(other.values(i), QList<int>({ i * 10 + 1, i * 10 }));
}
}
QTEST_APPLESS_MAIN(tst_QHash)
#include "tst_qhash.moc"