[−][src]Trait rayon::iter::plumbing::Producer
A Producer is effectively a "splittable IntoIterator". That
is, a producer is a value which can be converted into an iterator
at any time: at that point, it simply produces items on demand,
like any iterator. But what makes a Producer special is that,
before we convert to an iterator, we can also split it at a
particular point using the split_at method. This will yield up
two producers, one producing the items before that point, and one
producing the items after that point (these two producers can then
independently be split further, or be converted into iterators).
In Rayon, this splitting is used to divide between threads.
See the plumbing README for further details.
Note that each producer will always produce a fixed number of items N. However, this number N is not queryable through the API; the consumer is expected to track it.
NB. You might expect Producer to extend the IntoIterator
trait. However, rust-lang/rust#20671 prevents us from
declaring the DoubleEndedIterator and ExactSizeIterator
constraints on a required IntoIterator trait, so we inline
IntoIterator here until that issue is fixed.
Associated Types
type Item
The type of item that will be produced by this producer once it is converted into an iterator.
type IntoIter: Iterator<Item = Self::Item> + DoubleEndedIterator + ExactSizeIterator
The type of iterator we will become.
Required methods
fn into_iter(self) -> Self::IntoIter
Convert self into an iterator; at this point, no more parallel splits
are possible.
fn split_at(self, index: usize) -> (Self, Self)
Split into two producers; one produces items 0..index, the
other index..N. Index must be less than or equal to N.
Provided methods
fn min_len(&self) -> usize
The minimum number of items that we will process
sequentially. Defaults to 1, which means that we will split
all the way down to a single item. This can be raised higher
using the with_min_len method, which will force us to
create sequential tasks at a larger granularity. Note that
Rayon automatically normally attempts to adjust the size of
parallel splits to reduce overhead, so this should not be
needed.
fn max_len(&self) -> usize
The maximum number of items that we will process
sequentially. Defaults to MAX, which means that we can choose
not to split at all. This can be lowered using the
with_max_len method, which will force us to create more
parallel tasks. Note that Rayon automatically normally
attempts to adjust the size of parallel splits to reduce
overhead, so this should not be needed.
fn fold_with<F>(self, folder: F) -> F where
F: Folder<Self::Item>,
F: Folder<Self::Item>,
Iterate the producer, feeding each element to folder, and
stop when the folder is full (or all elements have been consumed).
The provided implementation is sufficient for most iterables.