- Qt 6.10
- Qt Concurrent
- QtConcurrent Namespace
- Qt 6.10.2 Reference Documentation

# QtConcurrent Namespace

The QtConcurrent namespace provides high-level APIs that make it possible to write multi-threaded programs without using low-level threading primitives. More...

Header: | `#include <QtConcurrent>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Concurrent)` `target_link_libraries(mytarget PRIVATE Qt6::Concurrent)`
qmake: | `QT += concurrent`

- QtConcurrent is part of Threading Classes.

## Classes

`(since 6.0)` class | QTaskBuilder

## Types

enum class | FutureResult { Ignore }
| InvokeResultType
enum | ReduceOption { UnorderedReduce, OrderedReduce, SequentialReduce }
flags | ReduceOptions

## Functions

void | blockingFilter(Sequence &sequence, KeepFunctor &&filterFunction)
void | blockingFilter(QThreadPool *pool, Sequence &sequence, KeepFunctor &&filterFunction)
std::decay_t<Sequence> | blockingFiltered(Sequence &&sequence, KeepFunctor &&filterFunction)
OutputSequence | blockingFiltered(Iterator begin, Iterator end, KeepFunctor &&filterFunction)
std::decay_t<Sequence> | blockingFiltered(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction)
OutputSequence | blockingFiltered(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction)
ResultType | blockingFilteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingFilteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
void | blockingMap(Sequence &&sequence, MapFunctor &&function)
void | blockingMap(Iterator begin, Iterator end, MapFunctor &&function)
void | blockingMap(QThreadPool *pool, Sequence &&sequence, MapFunctor function)
void | blockingMap(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)
OutputSequence | blockingMapped(InputSequence &&sequence, MapFunctor &&function)
Sequence | blockingMapped(Iterator begin, Iterator end, MapFunctor &&function)
OutputSequence | blockingMapped(QThreadPool *pool, InputSequence &&sequence, MapFunctor &&function)
Sequence | blockingMapped(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)
ResultType | blockingMappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
ResultType | blockingMappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<void> | filter(Sequence &sequence, KeepFunctor &&filterFunction)
QFuture<void> | filter(QThreadPool *pool, Sequence &sequence, KeepFunctor &&filterFunction)
QFuture<typename std::decay_t<Sequence>::value_type> | filtered(Sequence &&sequence, KeepFunctor &&filterFunction)
QFuture<typename qValueType<Iterator>::value_type> | filtered(Iterator begin, Iterator end, KeepFunctor &&filterFunction)
QFuture<typename std::decay_t<Sequence>::value_type> | filtered(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction)
QFuture<typename qValueType<Iterator>::value_type> | filtered(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction)
QFuture<ResultType> | filteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | filteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<void> | map(Sequence &&sequence, MapFunctor &&function)
QFuture<void> | map(Iterator begin, Iterator end, MapFunctor &&function)
QFuture<void> | map(QThreadPool *pool, Sequence &&sequence, MapFunctor &&function)
QFuture<void> | map(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)
QFuture<QtPrivate::MapResultType<Sequence, MapFunctor>> | mapped(Sequence &&sequence, MapFunctor &&function)
QFuture<QtPrivate::MapResultType<Iterator, MapFunctor>> | mapped(Iterator begin, Iterator end, MapFunctor &&function)
QFuture<QtPrivate::MapResultType<Sequence, MapFunctor>> | mapped(QThreadPool *pool, Sequence &&sequence, MapFunctor &&function)
QFuture<QtPrivate::MapResultType<Iterator, MapFunctor>> | mapped(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)
QFuture<ResultType> | mappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<ResultType> | mappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))
QFuture<T> | run(Function function, ...)
QFuture<T> | run(QThreadPool *pool, Function function, ...)
`(since 6.0)` QtConcurrent::QTaskBuilder<Task> | task(Task &&task)

## Detailed Description

See the Qt Concurrent module documentation for an overview of available functions, or see below for detailed information on each function.

### Optimize includes

If you include the `<QtConcurrent>` header, the entire Qt Concurrent module with the entire Qt Core module will be included, which may increase compilation times and binary sizes. To use individual functions from the QtConcurrent namespace, you can include more specific headers.

The table below lists the functions in the QtConcurrent namespace and their corresponding headers:

Function | Header
--- | ---
QtConcurrent::run() | `<QtConcurrentRun>`
QtConcurrent::task() | `<QtConcurrentTask>`
QtConcurrent::filter(), QtConcurrent::filtered(), QtConcurrent::filteredReduced() | `<QtConcurrentFilter>`
QtConcurrent::map(), QtConcurrent::mapped(), QtConcurrent::mappedReduced() | `<QtConcurrentMap>`

## Classes

### class QTaskBuilder

The QTaskBuilder class is used for adjusting task parameters. More...

## Type Documentation

### enum class QtConcurrent::FutureResult

This enum type is used to invoke a special overload of QtConcurrent::QTaskBuilder::spawn(QtConcurrent::FutureResult) that doesn't return a future object.

Constant | Value | Description
--- | --- | ---
`QtConcurrent::FutureResult::Ignore` | `0` | An auxiliary tag which introduced to improve code readability.

### `[alias]` InvokeResultType

The simplified definition of this type looks like this:

     template <class Task, class ...Args>
     using InvokeResultType = std::invoke_result_t<std::decay_t<Task>, std::decay_t<Args>...>;

The real implementation also contains a compile-time check for whether the task can be invoked with the specified arguments or not.

### enum QtConcurrent::ReduceOption
flags QtConcurrent::ReduceOptions

This enum specifies the order of which results from the map or filter function are passed to the reduce function.

Constant | Value | Description
--- | --- | ---
`QtConcurrent::UnorderedReduce` | `0x1` | Reduction is done in an arbitrary order.
`QtConcurrent::OrderedReduce` | `0x2` | Reduction is done in the order of the original sequence.
`QtConcurrent::SequentialReduce` | `0x4` | Reduction is done sequentially: only one thread will enter the reduce function at a time. (Parallel reduction might be supported in a future version of Qt Concurrent.)

The ReduceOptions type is a typedef for QFlags<ReduceOption>. It stores an OR combination of ReduceOption values.

## Function Documentation

### template <typename Sequence, typename KeepFunctor> void QtConcurrent::blockingFilter(Sequence &sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence. If filterFunction returns `true`, the item is kept in sequence; otherwise, the item is removed from sequence.

Note that this method doesn't have an overload working with iterators, because it invalidates the iterators of the sequence it operates on.

Note: This function will block until all items in the sequence have been processed.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> void QtConcurrent::blockingFilter(QThreadPool *pool, Sequence &sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, the item is kept in sequence; otherwise, the item is removed from sequence.

Note that this method doesn't have an overload working with iterators, because it invalidates the iterators of the sequence it operates on.

Note: This function will block until all items in the sequence have been processed.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> std::decay_t<Sequence> QtConcurrent::blockingFiltered(Sequence &&sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence and returns a new Sequence of kept items. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

Note: This function will block until all items in the sequence have been processed.

See also filtered() and Concurrent Filter and Filter-Reduce.

### template <typename OutputSequence, typename Iterator, typename KeepFunctor> OutputSequence QtConcurrent::blockingFiltered(Iterator begin, Iterator end, KeepFunctor &&filterFunction)

Calls filterFunction once for each item from begin to end and returns a new Sequence of kept items. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filtered() and Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> std::decay_t<Sequence> QtConcurrent::blockingFiltered(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence and returns a new Sequence of kept items. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

Note: This function will block until all items in the sequence have been processed.

See also filtered() and Concurrent Filter and Filter-Reduce.

### template <typename OutputSequence, typename Iterator, typename KeepFunctor> OutputSequence QtConcurrent::blockingFiltered(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction)

Calls filterFunction once for each item from begin to end and returns a new Sequence of kept items. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filtered() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingFilteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

Note: This function will block until all items in the sequence have been processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingFilteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingFilteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

Note: This function will block until all items in the sequence have been processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingFilteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

Note: This function will block until all items in the sequence have been processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingFilteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingFilteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingFilteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

Note: This function will block until all items in the sequence have been processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingFilteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also filteredReduced() and Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename MapFunctor> void QtConcurrent::blockingMap(Sequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence. The function takes a reference to the item, so that any modifications done to the item will appear in sequence.

Note: This function will block until all items in the sequence have been processed.

See also map() and Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> void QtConcurrent::blockingMap(Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end. The function takes a reference to the item, so that any modifications done to the item will appear in the sequence which the iterators belong to.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also map() and Concurrent Map and Map-Reduce.

### template <typename Sequence, typename MapFunctor> void QtConcurrent::blockingMap(QThreadPool *pool, Sequence &&sequence, MapFunctor function)

Calls function once for each item in sequence. All calls to function are invoked from the threads taken from the QThreadPool pool. The function takes a reference to the item, so that any modifications done to the item will appear in sequence.

Note: This function will block until all items in the sequence have been processed.

See also map() and Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> void QtConcurrent::blockingMap(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end. All calls to function are invoked from the threads taken from the QThreadPool pool. The function takes a reference to the item, so that any modifications done to the item will appear in the sequence which the iterators belong to.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also map() and Concurrent Map and Map-Reduce.

### template <typename OutputSequence, typename InputSequence, typename MapFunctor> OutputSequence QtConcurrent::blockingMapped(InputSequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence and returns an OutputSequence containing the results. The type of the results will match the type returned by the MapFunctor.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename Sequence, typename Iterator, typename MapFunctor> Sequence QtConcurrent::blockingMapped(Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end and returns a container with the results. You can specify the type of container as the a template argument, like this:

     QList<int> ints = QtConcurrent::blockingMapped<QList<int> >(beginIterator, endIterator, fn);

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename OutputSequence, typename InputSequence, typename MapFunctor> OutputSequence QtConcurrent::blockingMapped(QThreadPool *pool, InputSequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence and returns an OutputSequence containing the results. All calls to function are invoked from the threads taken from the QThreadPool pool. The type of the results will match the type returned by the MapFunctor.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename Sequence, typename Iterator, typename MapFunctor> Sequence QtConcurrent::blockingMapped(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end and returns a container with the results. All calls to function are invoked from the threads taken from the QThreadPool pool. You can specify the type of container as the a template argument, like this:

     QList<int> ints = QtConcurrent::blockingMapped<QList<int> >(beginIterator, endIterator, fn);

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingMappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingMappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also blockingMappedReduced() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingMappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingMappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingMappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also blockingMappedReduced() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor> ResultType QtConcurrent::blockingMappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also blockingMappedReduced() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingMappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

Note: This function will block until all items in the sequence have been processed.

See also mapped() and Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> ResultType QtConcurrent::blockingMappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined.

Note: This function will block until the iterator reaches the end of the sequence being processed.

See also blockingMappedReduced() and Concurrent Map and Map-Reduce.

### template <typename Sequence, typename KeepFunctor> QFuture<void> QtConcurrent::filter(Sequence &sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence. If filterFunction returns `true`, the item is kept in sequence; otherwise, the item is removed from sequence.

Note that this method doesn't have an overload working with iterators, because it invalidates the iterators of the sequence it operates on.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> QFuture<void> QtConcurrent::filter(QThreadPool *pool, Sequence &sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, the item is kept in sequence; otherwise, the item is removed from sequence.

Note that this method doesn't have an overload working with iterators, because it invalidates the iterators of the sequence it operates on.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> QFuture<typename std::decay_t<Sequence>::value_type> QtConcurrent::filtered(Sequence &&sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence and returns a new Sequence of kept items. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename Iterator, typename KeepFunctor> QFuture<typename qValueType<Iterator>::value_type> QtConcurrent::filtered(Iterator begin, Iterator end, KeepFunctor &&filterFunction)

Calls filterFunction once for each item from begin to end and returns a new Sequence of kept items. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename KeepFunctor> QFuture<typename std::decay_t<Sequence>::value_type> QtConcurrent::filtered(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction)

Calls filterFunction once for each item in sequence and returns a new Sequence of kept items. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename Iterator, typename KeepFunctor> QFuture<typename qValueType<Iterator>::value_type> QtConcurrent::filtered(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction)

Calls filterFunction once for each item from begin to end and returns a new Sequence of kept items. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true`, a copy of the item is put in the new Sequence. Otherwise, the item will not appear in the new Sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::filteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::filteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::filteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::filteredReduced(Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::filteredReduced(Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::filteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Sequence, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::filteredReduced(QThreadPool *pool, Sequence &&sequence, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item in sequence. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename ResultType, typename Iterator, typename KeepFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::filteredReduced(QThreadPool *pool, Iterator begin, Iterator end, KeepFunctor &&filterFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls filterFunction once for each item from begin to end. All calls to filterFunction are invoked from the threads taken from the QThreadPool pool. If filterFunction returns `true` for an item, that item is then passed to reduceFunction. In other words, the return value is the result of reduceFunction for each item where filterFunction returns `true`. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while filterFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is undefined if reduceOptions is QtConcurrent::UnorderedReduce. If reduceOptions is QtConcurrent::OrderedReduce, the reduceFunction is called in the order of the original sequence.

See also Concurrent Filter and Filter-Reduce.

### template <typename Sequence, typename MapFunctor> QFuture<void> QtConcurrent::map(Sequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence. The function takes a reference to the item, so that any modifications done to the item will appear in sequence.

See also Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> QFuture<void> QtConcurrent::map(Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end. The function takes a reference to the item, so that any modifications done to the item will appear in the sequence which the iterators belong to.

See also Concurrent Map and Map-Reduce.

### template <typename Sequence, typename MapFunctor> QFuture<void> QtConcurrent::map(QThreadPool *pool, Sequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence. All calls to function are invoked from the threads taken from the QThreadPool pool. The function takes a reference to the item, so that any modifications done to the item will appear in sequence.

See also Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> QFuture<void> QtConcurrent::map(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end. All calls to function are invoked from the threads taken from the QThreadPool pool. The function takes a reference to the item, so that any modifications done to the item will appear in the sequence which the iterators belong to.

See also Concurrent Map and Map-Reduce.

### template <typename Sequence, typename MapFunctor> QFuture<QtPrivate::MapResultType<Sequence, MapFunctor>> QtConcurrent::mapped(Sequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence and returns a future with each mapped item as a result. You can use QFuture::const_iterator or QFutureIterator to iterate through the results.

See also Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> QFuture<QtPrivate::MapResultType<Iterator, MapFunctor>> QtConcurrent::mapped(Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end and returns a future with each mapped item as a result. You can use QFuture::const_iterator or QFutureIterator to iterate through the results.

See also Concurrent Map and Map-Reduce.

### template <typename Sequence, typename MapFunctor> QFuture<QtPrivate::MapResultType<Sequence, MapFunctor>> QtConcurrent::mapped(QThreadPool *pool, Sequence &&sequence, MapFunctor &&function)

Calls function once for each item in sequence and returns a future with each mapped item as a result. All calls to function are invoked from the threads taken from the QThreadPool pool. You can use QFuture::const_iterator or QFutureIterator to iterate through the results.

See also Concurrent Map and Map-Reduce.

### template <typename Iterator, typename MapFunctor> QFuture<QtPrivate::MapResultType<Iterator, MapFunctor>> QtConcurrent::mapped(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&function)

Calls function once for each item from begin to end and returns a future with each mapped item as a result. All calls to function are invoked from the threads taken from the QThreadPool pool. You can use QFuture::const_iterator or QFutureIterator to iterate through the results.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::mappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::mappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. By default, the order in which reduceFunction is called is undefined.

Note: QtConcurrent::OrderedReduce results in the ordered reduction.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::mappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::mappedReduced(Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::mappedReduced(Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. By default, the order in which reduceFunction is called is undefined.

Note: QtConcurrent::OrderedReduce results in the ordered reduction.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor> QFuture<ResultType> QtConcurrent::mappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. By default, the order in which reduceFunction is called is undefined.

Note: QtConcurrent::OrderedReduce results in the ordered reduction.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Sequence, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::mappedReduced(QThreadPool *pool, Sequence &&sequence, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item in sequence. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. The order in which reduceFunction is called is determined by reduceOptions.

See also Concurrent Map and Map-Reduce.

### template <typename ResultType, typename Iterator, typename MapFunctor, typename ReduceFunctor, typename InitialValueType> QFuture<ResultType> QtConcurrent::mappedReduced(QThreadPool *pool, Iterator begin, Iterator end, MapFunctor &&mapFunction, ReduceFunctor &&reduceFunction, InitialValueType &&initialValue, QtConcurrent::ReduceOptions reduceOptions = ReduceOptions(UnorderedReduce | SequentialReduce))

Calls mapFunction once for each item from begin to end. All calls to mapFunction are invoked from the threads taken from the QThreadPool pool. The return value of each mapFunction is passed to reduceFunction. The result value is initialized to initialValue when the function is called, and the first call to reduceFunction will operate on this value.

Note that while mapFunction is called concurrently, only one thread at a time will call reduceFunction. By default, the order in which reduceFunction is called is undefined.

Note: QtConcurrent::OrderedReduce results in the ordered reduction.

See also Concurrent Map and Map-Reduce.

### template <typename T> QFuture<T> QtConcurrent::run(Function function, ...)

Equivalent to

     QtConcurrent::run(QThreadPool::globalInstance(), function, ...);

Runs function in a separate thread. The thread is taken from the global QThreadPool. Note that function may not run immediately; function will only be run once a thread becomes available.

In basic mode T is the same type as the return value of function. Non-void return values can be accessed via the QFuture::result() function.

In basic mode the QFuture returned can only be used to query for the running/finished status and the return value of the function. In particular, canceling or pausing can be issued only if the computations behind the future has not been started.

In run with promise mode, the function is expected to return void and must take an additional argument of `QPromise<T> &` type, placed as a first argument in function's argument list. T is the result type and it is the same for the returned `QFuture<T>`.

In run with promise mode, similar to basic mode, the QFuture returned can be used to query for the running/finished status and the value reported by the function. In addition, it may be used for suspending or canceling the running task, fetching multiple results from the called function or monitoring progress reported by the function.

See also Concurrent Run (basic mode), Concurrent Run With Promise, and QThreadPool::start().

### template <typename T> QFuture<T> QtConcurrent::run(QThreadPool *pool, Function function, ...)

Schedules function on pool. Note that function may not run immediately; function will only be run once a thread becomes available.

In basic mode T is the same type as the return value of function. Non-void return values can be accessed via the QFuture::result() function.

In basic mode the QFuture returned can only be used to query for the running/finished status and the return value of the function. In particular, canceling or pausing can be issued only if the computations behind the future has not been started.

In run with promise mode, the function is expected to return void and must take an additional argument of `QPromise<T> &` type, placed as a first argument in function's argument list. T is the result type and it is the same for the returned `QFuture<T>`.

In run with promise mode, similar to basic mode, the QFuture returned can be used to query for the running/finished status and the value reported by the function. In addition, it may be used for suspending or canceling the running task, fetching multiple results from the called function or monitoring progress reported by the function.

See also Concurrent Run (basic mode), Concurrent Run With Promise, and QThreadPool::start().

### `[since 6.0]` template <typename Task> QtConcurrent::QTaskBuilder<Task> QtConcurrent::task(Task &&task)

Creates an instance of QtConcurrent::QTaskBuilder. This object can be used to adjust some parameters and run task in a separate thread.

This function was introduced in Qt 6.0.

See also Concurrent Task and QtConcurrent::QTaskBuilder.