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Intel Threading Building Blocks
book

Intel Threading Building Blocks

by James Reinders
July 2007
Intermediate to advanced content levelIntermediate to advanced
332 pages
10h 4m
English
O'Reilly Media, Inc.
Content preview from Intel Threading Building Blocks

Name

parallel_while Template Class — Template class that processes work items.

Synopsis

#include "tbb/parallel_while.h"

template<typename Body> class parallel_while;

Description

A parallel_while<Body> performs parallel iteration over items. The processing to be performed on each item is defined by a function object of type Body. The items are specified in two ways:

  • An initial stream of items

  • Additional items that are added while the stream is being processed

Table 4-1 shows the requirements on the stream and body.

Table 4-1. Requirements for parallel_while stream and body

Pseudosignature

Semantics

boolS::pop_if_present(B::argument_type&item)

Get next stream item. parallel_while does not concurrently invoke the method on the same object.

B::operator()(B::argument_type&item) const

Process item. parallel_while may concurrently invoke the operator for the same object but a different item.

B::argument_type()

Default constructor.

B::argument_type(constB::argument_type&)

Copy constructor.

~B::argument_type()

Destructor.

For example, a unary function object, as defined in Section 20.3 of the C++ standard, models the requirements for B. A concurrent_queue models the requirements for S.

Tip

To achieve speedup, the grain size of B::operator() needs to be on the order of 10,000 instructions to execute. Otherwise, the internal over-heads of parallel_while swamp the useful work. The parallelism in parallel_while is not scalable if all the items come from the input stream. To achieve ...

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Publisher Resources

ISBN: 9780596514808Errata Page