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Diffstat (limited to 'vendor/rayon/src/iter/collect/consumer.rs')
| -rw-r--r-- | vendor/rayon/src/iter/collect/consumer.rs | 186 |
1 files changed, 0 insertions, 186 deletions
diff --git a/vendor/rayon/src/iter/collect/consumer.rs b/vendor/rayon/src/iter/collect/consumer.rs deleted file mode 100644 index acd67df..0000000 --- a/vendor/rayon/src/iter/collect/consumer.rs +++ /dev/null @@ -1,186 +0,0 @@ -use super::super::plumbing::*; -use crate::SendPtr; -use std::marker::PhantomData; -use std::ptr; -use std::slice; - -pub(super) struct CollectConsumer<'c, T: Send> { - /// See `CollectResult` for explanation of why this is not a slice - start: SendPtr<T>, - len: usize, - marker: PhantomData<&'c mut T>, -} - -impl<T: Send> CollectConsumer<'_, T> { - /// Create a collector for `len` items in the unused capacity of the vector. - pub(super) fn appender(vec: &mut Vec<T>, len: usize) -> CollectConsumer<'_, T> { - let start = vec.len(); - assert!(vec.capacity() - start >= len); - - // SAFETY: We already made sure to have the additional space allocated. - // The pointer is derived from `Vec` directly, not through a `Deref`, - // so it has provenance over the whole allocation. - unsafe { CollectConsumer::new(vec.as_mut_ptr().add(start), len) } - } -} - -impl<'c, T: Send + 'c> CollectConsumer<'c, T> { - /// The target memory is considered uninitialized, and will be - /// overwritten without reading or dropping existing values. - unsafe fn new(start: *mut T, len: usize) -> Self { - CollectConsumer { - start: SendPtr(start), - len, - marker: PhantomData, - } - } -} - -/// CollectResult represents an initialized part of the target slice. -/// -/// This is a proxy owner of the elements in the slice; when it drops, -/// the elements will be dropped, unless its ownership is released before then. -#[must_use] -pub(super) struct CollectResult<'c, T> { - /// This pointer and length has the same representation as a slice, - /// but retains the provenance of the entire array so that we can merge - /// these regions together in `CollectReducer`. - start: SendPtr<T>, - total_len: usize, - /// The current initialized length after `start` - initialized_len: usize, - /// Lifetime invariance guarantees that the data flows from consumer to result, - /// especially for the `scope_fn` callback in `Collect::with_consumer`. - invariant_lifetime: PhantomData<&'c mut &'c mut [T]>, -} - -unsafe impl<'c, T> Send for CollectResult<'c, T> where T: Send {} - -impl<'c, T> CollectResult<'c, T> { - /// The current length of the collect result - pub(super) fn len(&self) -> usize { - self.initialized_len - } - - /// Release ownership of the slice of elements, and return the length - pub(super) fn release_ownership(mut self) -> usize { - let ret = self.initialized_len; - self.initialized_len = 0; - ret - } -} - -impl<'c, T> Drop for CollectResult<'c, T> { - fn drop(&mut self) { - // Drop the first `self.initialized_len` elements, which have been recorded - // to be initialized by the folder. - unsafe { - ptr::drop_in_place(slice::from_raw_parts_mut( - self.start.0, - self.initialized_len, - )); - } - } -} - -impl<'c, T: Send + 'c> Consumer<T> for CollectConsumer<'c, T> { - type Folder = CollectResult<'c, T>; - type Reducer = CollectReducer; - type Result = CollectResult<'c, T>; - - fn split_at(self, index: usize) -> (Self, Self, CollectReducer) { - let CollectConsumer { start, len, .. } = self; - - // Produce new consumers. - // SAFETY: This assert checks that `index` is a valid offset for `start` - unsafe { - assert!(index <= len); - ( - CollectConsumer::new(start.0, index), - CollectConsumer::new(start.0.add(index), len - index), - CollectReducer, - ) - } - } - - fn into_folder(self) -> Self::Folder { - // Create a result/folder that consumes values and writes them - // into the region after start. The initial result has length 0. - CollectResult { - start: self.start, - total_len: self.len, - initialized_len: 0, - invariant_lifetime: PhantomData, - } - } - - fn full(&self) -> bool { - false - } -} - -impl<'c, T: Send + 'c> Folder<T> for CollectResult<'c, T> { - type Result = Self; - - fn consume(mut self, item: T) -> Self { - assert!( - self.initialized_len < self.total_len, - "too many values pushed to consumer" - ); - - // SAFETY: The assert above is a bounds check for this write, and we - // avoid assignment here so we do not drop an uninitialized T. - unsafe { - // Write item and increase the initialized length - self.start.0.add(self.initialized_len).write(item); - self.initialized_len += 1; - } - - self - } - - fn complete(self) -> Self::Result { - // NB: We don't explicitly check that the local writes were complete, - // but Collect will assert the total result length in the end. - self - } - - fn full(&self) -> bool { - false - } -} - -/// Pretend to be unindexed for `special_collect_into_vec`, -/// but we should never actually get used that way... -impl<'c, T: Send + 'c> UnindexedConsumer<T> for CollectConsumer<'c, T> { - fn split_off_left(&self) -> Self { - unreachable!("CollectConsumer must be indexed!") - } - fn to_reducer(&self) -> Self::Reducer { - CollectReducer - } -} - -/// CollectReducer combines adjacent chunks; the result must always -/// be contiguous so that it is one combined slice. -pub(super) struct CollectReducer; - -impl<'c, T> Reducer<CollectResult<'c, T>> for CollectReducer { - fn reduce( - self, - mut left: CollectResult<'c, T>, - right: CollectResult<'c, T>, - ) -> CollectResult<'c, T> { - // Merge if the CollectResults are adjacent and in left to right order - // else: drop the right piece now and total length will end up short in the end, - // when the correctness of the collected result is asserted. - unsafe { - let left_end = left.start.0.add(left.initialized_len); - if left_end == right.start.0 { - left.total_len += right.total_len; - left.initialized_len += right.release_ownership(); - } - left - } - } -} |