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Move existing items when inserting instead of copying them

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Use move operations to move existing items instead of copying
them. This speeds up insertions for non relocatable types
significantly (e.g. for std::string).

Change-Id: I308f381ac2242e50505f02675c2d2afbf21069d1
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Lars Knoll 2020-11-04 12:07:06 +01:00 committed by Andrei Golubev
parent 2768270573
commit 1d309843a1
1 changed files with 28 additions and 33 deletions
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61
src/corelib/tools/qarraydataops.h
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@ -566,8 +566,8 @@ public:
// Array may be truncated at where in case of exceptions
T *const end = this->end();
const T *readIter = end;
T *end = this->end();
T *readIter = end;
T *writeIter = end + (e - b);
const T *const step1End = where + qMax(e - b, end - where);
@ -578,7 +578,7 @@ public:
while (writeIter != step1End) {
--readIter;
// If exception happens on construction, we should not call ~T()
new (writeIter - 1) T(*readIter);
new (writeIter - 1) T(std::move(*readIter));
--writeIter;
}
@ -596,7 +596,7 @@ public:
while (readIter != where) {
--readIter;
--writeIter;
*writeIter = *readIter;
*writeIter = std::move(*readIter);
}
while (writeIter != where) {
@ -617,8 +617,8 @@ public:
typedef typename QArrayExceptionSafetyPrimitives<T>::template Destructor<T *> Destructor;
T *const begin = this->begin();
const T *readIter = begin;
T *begin = this->begin();
T *readIter = begin;
T *writeIter = begin - (e - b);
const T *const step1End = where - qMax(e - b, where - begin);
@ -627,7 +627,7 @@ public:
// Construct new elements in array
while (writeIter != step1End) {
new (writeIter) T(*readIter);
new (writeIter) T(std::move(*readIter));
++readIter;
++writeIter;
}
@ -644,7 +644,7 @@ public:
// Copy assign over existing elements
while (readIter != where) {
*writeIter = *readIter;
*writeIter = std::move(*readIter);
++readIter;
++writeIter;
}
@ -669,8 +669,8 @@ public:
typedef typename QArrayExceptionSafetyPrimitives<T>::template Destructor<T *> Destructor;
// Array may be truncated at where in case of exceptions
T *const end = this->end();
const T *readIter = end;
T *end = this->end();
T *readIter = end;
T *writeIter = end + n;
const T *const step1End = where + qMax<size_t>(n, end - where);
@ -681,7 +681,7 @@ public:
while (writeIter != step1End) {
--readIter;
// If exception happens on construction, we should not call ~T()
new (writeIter - 1) T(*readIter);
new (writeIter - 1) T(std::move(*readIter));
--writeIter;
}
@ -699,7 +699,7 @@ public:
while (readIter != where) {
--readIter;
--writeIter;
*writeIter = *readIter;
*writeIter = std::move(*readIter);
}
while (writeIter != where) {
@ -718,8 +718,8 @@ public:
typedef typename QArrayExceptionSafetyPrimitives<T>::template Destructor<T *> Destructor;
T *const begin = this->begin();
const T *readIter = begin;
T *begin = this->begin();
T *readIter = begin;
T *writeIter = begin - n;
const T *const step1End = where - qMax<size_t>(n, where - begin);
@ -728,7 +728,7 @@ public:
// Construct new elements in array
while (writeIter != step1End) {
new (writeIter) T(*readIter);
new (writeIter) T(std::move(*readIter));
++readIter;
++writeIter;
}
@ -744,7 +744,7 @@ public:
// Copy assign over existing elements
while (readIter != where) {
*writeIter = *readIter;
*writeIter = std::move(*readIter);
++readIter;
++writeIter;
}
@ -1225,23 +1225,18 @@ public:
detached->copyAppend(where, this->constEnd());
this->swap(detached);
} else {
// we're detached and we can just move data around
if (i == this->size && n <= this->freeSpaceAtEnd()) {
copyAppend(n, t);
} else {
T copy(t);
// Insert elements based on the divided distance. Good case: only 1
// insert happens (either to the front part or to the back part). Bad
// case: both inserts happen, meaning that we touch all N elements in
// the container (this should be handled "outside" by ensuring enough
// free space by reallocating more frequently)
T *where = this->begin() + i;
const auto beginSize = sizeToInsertAtBegin(where, n);
if (beginSize)
Base::insert(GrowsBackwardsTag{}, where, beginSize, copy);
if (n - beginSize)
Base::insert(GrowsForwardTag{}, where, n - beginSize, copy);
}
T copy(t);
// Insert elements based on the divided distance. Good case: only 1
// insert happens (either to the front part or to the back part). Bad
// case: both inserts happen, meaning that we touch all N elements in
// the container (this should be handled "outside" by ensuring enough
// free space by reallocating more frequently)
T *where = this->begin() + i;
const auto beginSize = sizeToInsertAtBegin(where, n);
if (beginSize)
Base::insert(GrowsBackwardsTag{}, where, beginSize, copy);
if (n - beginSize)
Base::insert(GrowsForwardTag{}, where, n - beginSize, copy);
}
}