1berry/qtbase
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

QVector: always grow exponentially

Browse Source 
For non-movable types (QTypeInfo<T>::isStatic), QVector would grow the
array linearly, and defer to qAllocMore otherwise. That property,
however, gives no indication as to how the vector will grow.

By forcing additional allocations for growing containers of such types,
this penalized exactly those objects which are more expensive to move.

We now let qAllocMore reign in growth decisions.

Change-Id: I843a89dcdc21d09868c6b62a846a7e1e4548e399
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
This commit is contained in:
João Abecasis 2012-02-16 23:53:58 +01:00 committed by Qt by Nokia
parent fb8be9905d
commit fd96115ae8
3 changed files with 8 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/corelib/tools/qvector.cpp
View File

@ -76,10 +76,8 @@ void QVectorData::free(QVectorData *x, int alignment)
::free(x);
}
int QVectorData::grow(int sizeofTypedData, int size, int sizeofT, bool excessive)
int QVectorData::grow(int sizeofTypedData, int size, int sizeofT)
{
if (excessive)
return size + size / 2;
return qAllocMore(size * sizeofT, sizeofTypedData - sizeofT) / sizeofT;
}

9
src/corelib/tools/qvector.h
View File

@ -80,7 +80,7 @@ struct Q_CORE_EXPORT QVectorData
static QVectorData *allocate(int size, int alignment);
static QVectorData *reallocate(QVectorData *old, int newsize, int oldsize, int alignment);
static void free(QVectorData *data, int alignment);
static int grow(int sizeofTypedData, int size, int sizeofT, bool excessive);
static int grow(int sizeofTypedData, int size, int sizeofT);
};
template <typename T>
@ -355,7 +355,7 @@ void QVector<T>::reserve(int asize)
template <typename T>
void QVector<T>::resize(int asize)
{ realloc(asize, (asize > d->alloc || (!d->capacity && asize < d->size && asize < (d->alloc >> 1))) ?
QVectorData::grow(sizeOfTypedData(), asize, sizeof(T), QTypeInfo<T>::isStatic)
QVectorData::grow(sizeOfTypedData(), asize, sizeof(T))
: d->alloc); }
template <typename T>
inline void QVector<T>::clear()
@ -582,7 +582,7 @@ void QVector<T>::append(const T &t)
if (!isDetached() || d->size + 1 > d->alloc) {
const T copy(t);
realloc(d->size, (d->size + 1 > d->alloc) ?
QVectorData::grow(sizeOfTypedData(), d->size + 1, sizeof(T), QTypeInfo<T>::isStatic)
QVectorData::grow(sizeOfTypedData(), d->size + 1, sizeof(T))
: d->alloc);
if (QTypeInfo<T>::isComplex)
new (p->array + d->size) T(copy);
@ -604,8 +604,7 @@ typename QVector<T>::iterator QVector<T>::insert(iterator before, size_type n, c
if (n != 0) {
const T copy(t);
if (!isDetached() || d->size + n > d->alloc)
realloc(d->size, QVectorData::grow(sizeOfTypedData(), d->size + n, sizeof(T),
QTypeInfo<T>::isStatic));
realloc(d->size, QVectorData::grow(sizeOfTypedData(), d->size + n, sizeof(T)));
if (QTypeInfo<T>::isStatic) {
T *b = p->array + d->size;
T *i = p->array + d->size + n;

8
tests/benchmarks/corelib/tools/qvector/qrawvector.h
View File

@ -308,7 +308,7 @@ void QRawVector<T>::reserve(int asize)
template <typename T>
void QRawVector<T>::resize(int asize)
{ realloc(asize, (asize > m_alloc || (asize < m_size && asize < (m_alloc >> 1)))
? QVectorData::grow(sizeOfTypedData(), asize, sizeof(T), QTypeInfo<T>::isStatic)
? QVectorData::grow(sizeOfTypedData(), asize, sizeof(T))
: m_alloc, false); }
template <typename T>
inline void QRawVector<T>::clear()
@ -510,8 +510,7 @@ void QRawVector<T>::append(const T &t)
{
if (m_size + 1 > m_alloc) {
const T copy(t);
realloc(m_size, QVectorData::grow(sizeOfTypedData(), m_size + 1, sizeof(T),
QTypeInfo<T>::isStatic), false);
realloc(m_size, QVectorData::grow(sizeOfTypedData(), m_size + 1, sizeof(T)), false);
if (QTypeInfo<T>::isComplex)
new (m_begin + m_size) T(copy);
else
@ -532,8 +531,7 @@ typename QRawVector<T>::iterator QRawVector<T>::insert(iterator before, size_typ
if (n != 0) {
const T copy(t);
if (m_size + n > m_alloc)
realloc(m_size, QVectorData::grow(sizeOfTypedData(), m_size + n, sizeof(T),
QTypeInfo<T>::isStatic), false);
realloc(m_size, QVectorData::grow(sizeOfTypedData(), m_size + n, sizeof(T)), false);
if (QTypeInfo<T>::isStatic) {
T *b = m_begin + m_size;
T *i = m_begin + m_size + n;