Intel Threading Building Blocks

Name

Partitioner Concept — Requirements for a type that decides whether a range should be operated on by a task body or further split. Table 3-4 lists the requirements for a partitioner type P.

Synopsis

Table 3-4. Partitioner Concept

Pseudosignature	Semantics
P::~P()	Destructor.
template <typename Range> bool P::should_execute_range( const Range &r, const task &t)	True if r should be passed to the body of t.False if r should instead be split.
P::P( P& p, split )	Split pinto two partitioners.

Description

The partitioner implements rules for deciding when a given range should no longer be subdivided, but should be operated over as a whole by a task’s body.

The default behavior of the algorithms parallel_for, parallel_reduce, and parallel_scan is to recursively split a range until no subrange remains that is divisible, as decided by the function is_divisible of the Range Concept. The Partitioner Concept models rules for the early termination of the recursive splitting of a range, providing the ability to change the default behavior. A Partitioner object’s decision making is implemented using two functions: a splitting constructor and the function should_execute_range.

Within the parallel algorithms, each Range object is associated with a Partitioner object. Whenever a Range object is split using its splitting constructor to create two subranges, the associated Partitioner object is likewise split to create two matching Partitioner objects.

When a parallel_for, parallel_reduce ...