Intel Threading Building Blocks

Name

parallel_for<Range,Body> Template Function — Template for a function that performs parallel iteration over a range of values.

Synopsis

#include "tbb/parallel_for.h"

template<typename Range, typename Body>

void parallel_for( const Range& range, const Body& body );

template<typename Range, typename Body, typename Partitioner>

  void parallel_for( const Range& range, const Body& body,

                      Partitioner &partitioner );

Description

A parallel_for<Range,Body> represents parallel execution of Body over each value in Range. Type Range must model the Range Concept. The body must model the requirements in Table 3-6.

Table 3-6. Requirements for parallel_for body

Pseudosignature	Semantics
Body::Body (const Body&)	Copy constructor
Body::~Body()	Destructor
void Body::operator()(Range&range) const	Apply body to range

A parallel_for recursively splits the range into subranges to the point where is_divisible() returns false for each subrange, and makes copies of the body for each of these subranges. For each such body/subrange pair, it invokes Body::operator(). The invocations are interleaved with the recursive splitting in order to minimize space overhead and efficiently use the cache.

Some of the copies of the range and body may be destroyed after parallel_for returns. This late destruction is not an issue in typical usage, but it is something to be aware of when looking at execution traces or writing range or body objects with complex side effects.

When worker threads are available, parallel_for ...