Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 329 insertions, 0 deletions

diff --git a/third_party/rust/range-alloc/src/lib.rs b/third_party/rust/range-alloc/src/lib.rs
new file mode 100644
index 0000000000..767d31e909
--- /dev/null
+++ b/third_party/rust/range-alloc/src/lib.rs
@@ -0,0 +1,329 @@
+use std::{
+    fmt::Debug,
+    iter::Sum,
+    ops::{Add, AddAssign, Range, Sub},
+};
+
+#[derive(Debug)]
+pub struct RangeAllocator<T> {
+    /// The range this allocator covers.
+    initial_range: Range<T>,
+    /// A Vec of ranges in this heap which are unused.
+    /// Must be ordered with ascending range start to permit short circuiting allocation.
+    /// No two ranges in this vec may overlap.
+    free_ranges: Vec<Range<T>>,
+}
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct RangeAllocationError<T> {
+    pub fragmented_free_length: T,
+}
+
+impl<T> RangeAllocator<T>
+where
+    T: Clone + Copy + Add<Output = T> + AddAssign + Sub<Output = T> + Eq + PartialOrd + Debug,
+{
+    pub fn new(range: Range<T>) -> Self {
+        RangeAllocator {
+            initial_range: range.clone(),
+            free_ranges: vec![range],
+        }
+    }
+
+    pub fn initial_range(&self) -> &Range<T> {
+        &self.initial_range
+    }
+
+    pub fn grow_to(&mut self, new_end: T) {
+        if let Some(last_range) = self.free_ranges.last_mut() {
+            last_range.end = new_end;
+        } else {
+            self.free_ranges.push(self.initial_range.end..new_end);
+        }
+
+        self.initial_range.end = new_end;
+    }
+
+    pub fn allocate_range(&mut self, length: T) -> Result<Range<T>, RangeAllocationError<T>> {
+        assert_ne!(length + length, length);
+        let mut best_fit: Option<(usize, Range<T>)> = None;
+
+        // This is actually correct. With the trait bound as it is, we have
+        // no way to summon a value of 0 directly, so we make one by subtracting
+        // something from itself. Once the trait bound can be changed, this can
+        // be fixed.
+        #[allow(clippy::eq_op)]
+        let mut fragmented_free_length = length - length;
+        for (index, range) in self.free_ranges.iter().cloned().enumerate() {
+            let range_length = range.end - range.start;
+            fragmented_free_length += range_length;
+            if range_length < length {
+                continue;
+            } else if range_length == length {
+                // Found a perfect fit, so stop looking.
+                best_fit = Some((index, range));
+                break;
+            }
+            best_fit = Some(match best_fit {
+                Some((best_index, best_range)) => {
+                    // Find best fit for this allocation to reduce memory fragmentation.
+                    if range_length < best_range.end - best_range.start {
+                        (index, range)
+                    } else {
+                        (best_index, best_range.clone())
+                    }
+                }
+                None => (index, range),
+            });
+        }
+        match best_fit {
+            Some((index, range)) => {
+                if range.end - range.start == length {
+                    self.free_ranges.remove(index);
+                } else {
+                    self.free_ranges[index].start += length;
+                }
+                Ok(range.start..(range.start + length))
+            }
+            None => Err(RangeAllocationError {
+                fragmented_free_length,
+            }),
+        }
+    }
+
+    pub fn free_range(&mut self, range: Range<T>) {
+        assert!(self.initial_range.start <= range.start && range.end <= self.initial_range.end);
+        assert!(range.start < range.end);
+
+        // Get insertion position.
+        let i = self
+            .free_ranges
+            .iter()
+            .position(|r| r.start > range.start)
+            .unwrap_or(self.free_ranges.len());
+
+        // Try merging with neighboring ranges in the free list.
+        // Before: |left|-(range)-|right|
+        if i > 0 && range.start == self.free_ranges[i - 1].end {
+            // Merge with |left|.
+            self.free_ranges[i - 1].end =
+                if i < self.free_ranges.len() && range.end == self.free_ranges[i].start {
+                    // Check for possible merge with |left| and |right|.
+                    let right = self.free_ranges.remove(i);
+                    right.end
+                } else {
+                    range.end
+                };
+
+            return;
+        } else if i < self.free_ranges.len() && range.end == self.free_ranges[i].start {
+            // Merge with |right|.
+            self.free_ranges[i].start = if i > 0 && range.start == self.free_ranges[i - 1].end {
+                // Check for possible merge with |left| and |right|.
+                let left = self.free_ranges.remove(i - 1);
+                left.start
+            } else {
+                range.start
+            };
+
+            return;
+        }
+
+        // Debug checks
+        assert!(
+            (i == 0 || self.free_ranges[i - 1].end < range.start)
+                && (i >= self.free_ranges.len() || range.end < self.free_ranges[i].start)
+        );
+
+        self.free_ranges.insert(i, range);
+    }
+
+    /// Returns an iterator over allocated non-empty ranges
+    pub fn allocated_ranges(&self) -> impl Iterator<Item = Range<T>> + '_ {
+        let first = match self.free_ranges.first() {
+            Some(Range { ref start, .. }) if *start > self.initial_range.start => {
+                Some(self.initial_range.start..*start)
+            }
+            None => Some(self.initial_range.clone()),
+            _ => None,
+        };
+
+        let last = match self.free_ranges.last() {
+            Some(Range { end, .. }) if *end < self.initial_range.end => {
+                Some(*end..self.initial_range.end)
+            }
+            _ => None,
+        };
+
+        let mid = self
+            .free_ranges
+            .iter()
+            .zip(self.free_ranges.iter().skip(1))
+            .map(|(ra, rb)| ra.end..rb.start);
+
+        first.into_iter().chain(mid).chain(last)
+    }
+
+    pub fn reset(&mut self) {
+        self.free_ranges.clear();
+        self.free_ranges.push(self.initial_range.clone());
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.free_ranges.len() == 1 && self.free_ranges[0] == self.initial_range
+    }
+}
+
+impl<T: Copy + Sub<Output = T> + Sum> RangeAllocator<T> {
+    pub fn total_available(&self) -> T {
+        self.free_ranges
+            .iter()
+            .map(|range| range.end - range.start)
+            .sum()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_basic_allocation() {
+        let mut alloc = RangeAllocator::new(0..10);
+        // Test if an allocation works
+        assert_eq!(alloc.allocate_range(4), Ok(0..4));
+        assert!(alloc.allocated_ranges().eq(std::iter::once(0..4)));
+        // Free the prior allocation
+        alloc.free_range(0..4);
+        // Make sure the free actually worked
+        assert_eq!(alloc.free_ranges, vec![0..10]);
+        assert!(alloc.allocated_ranges().eq(std::iter::empty()));
+    }
+
+    #[test]
+    fn test_out_of_space() {
+        let mut alloc = RangeAllocator::new(0..10);
+        // Test if the allocator runs out of space correctly
+        assert_eq!(alloc.allocate_range(10), Ok(0..10));
+        assert!(alloc.allocated_ranges().eq(std::iter::once(0..10)));
+        assert!(alloc.allocate_range(4).is_err());
+        alloc.free_range(0..10);
+    }
+
+    #[test]
+    fn test_grow() {
+        let mut alloc = RangeAllocator::new(0..11);
+        // Test if the allocator runs out of space correctly
+        assert_eq!(alloc.allocate_range(10), Ok(0..10));
+        assert!(alloc.allocated_ranges().eq(std::iter::once(0..10)));
+        assert!(alloc.allocate_range(4).is_err());
+        alloc.grow_to(20);
+        assert_eq!(alloc.allocate_range(4), Ok(10..14));
+        alloc.free_range(0..14);
+    }
+
+    #[test]
+    fn test_dont_use_block_that_is_too_small() {
+        let mut alloc = RangeAllocator::new(0..10);
+        // Allocate three blocks then free the middle one and check for correct state
+        assert_eq!(alloc.allocate_range(3), Ok(0..3));
+        assert_eq!(alloc.allocate_range(3), Ok(3..6));
+        assert_eq!(alloc.allocate_range(3), Ok(6..9));
+        alloc.free_range(3..6);
+        assert_eq!(alloc.free_ranges, vec![3..6, 9..10]);
+        assert_eq!(
+            alloc.allocated_ranges().collect::<Vec<Range<i32>>>(),
+            vec![0..3, 6..9]
+        );
+        // Now request space that the middle block can fill, but the end one can't.
+        assert_eq!(alloc.allocate_range(3), Ok(3..6));
+    }
+
+    #[test]
+    fn test_free_blocks_in_middle() {
+        let mut alloc = RangeAllocator::new(0..100);
+        // Allocate many blocks then free every other block.
+        assert_eq!(alloc.allocate_range(10), Ok(0..10));
+        assert_eq!(alloc.allocate_range(10), Ok(10..20));
+        assert_eq!(alloc.allocate_range(10), Ok(20..30));
+        assert_eq!(alloc.allocate_range(10), Ok(30..40));
+        assert_eq!(alloc.allocate_range(10), Ok(40..50));
+        assert_eq!(alloc.allocate_range(10), Ok(50..60));
+        assert_eq!(alloc.allocate_range(10), Ok(60..70));
+        assert_eq!(alloc.allocate_range(10), Ok(70..80));
+        assert_eq!(alloc.allocate_range(10), Ok(80..90));
+        assert_eq!(alloc.allocate_range(10), Ok(90..100));
+        assert_eq!(alloc.free_ranges, vec![]);
+        assert!(alloc.allocated_ranges().eq(std::iter::once(0..100)));
+        alloc.free_range(10..20);
+        alloc.free_range(30..40);
+        alloc.free_range(50..60);
+        alloc.free_range(70..80);
+        alloc.free_range(90..100);
+        // Check that the right blocks were freed.
+        assert_eq!(
+            alloc.free_ranges,
+            vec![10..20, 30..40, 50..60, 70..80, 90..100]
+        );
+        assert_eq!(
+            alloc.allocated_ranges().collect::<Vec<Range<i32>>>(),
+            vec![0..10, 20..30, 40..50, 60..70, 80..90]
+        );
+        // Fragment the memory on purpose a bit.
+        assert_eq!(alloc.allocate_range(6), Ok(10..16));
+        assert_eq!(alloc.allocate_range(6), Ok(30..36));
+        assert_eq!(alloc.allocate_range(6), Ok(50..56));
+        assert_eq!(alloc.allocate_range(6), Ok(70..76));
+        assert_eq!(alloc.allocate_range(6), Ok(90..96));
+        // Check for fragmentation.
+        assert_eq!(
+            alloc.free_ranges,
+            vec![16..20, 36..40, 56..60, 76..80, 96..100]
+        );
+        assert_eq!(
+            alloc.allocated_ranges().collect::<Vec<Range<i32>>>(),
+            vec![0..16, 20..36, 40..56, 60..76, 80..96]
+        );
+        // Fill up the fragmentation
+        assert_eq!(alloc.allocate_range(4), Ok(16..20));
+        assert_eq!(alloc.allocate_range(4), Ok(36..40));
+        assert_eq!(alloc.allocate_range(4), Ok(56..60));
+        assert_eq!(alloc.allocate_range(4), Ok(76..80));
+        assert_eq!(alloc.allocate_range(4), Ok(96..100));
+        // Check that nothing is free.
+        assert_eq!(alloc.free_ranges, vec![]);
+        assert!(alloc.allocated_ranges().eq(std::iter::once(0..100)));
+    }
+
+    #[test]
+    fn test_ignore_block_if_another_fits_better() {
+        let mut alloc = RangeAllocator::new(0..10);
+        // Allocate blocks such that the only free spaces available are 3..6 and 9..10
+        // in order to prepare for the next test.
+        assert_eq!(alloc.allocate_range(3), Ok(0..3));
+        assert_eq!(alloc.allocate_range(3), Ok(3..6));
+        assert_eq!(alloc.allocate_range(3), Ok(6..9));
+        alloc.free_range(3..6);
+        assert_eq!(alloc.free_ranges, vec![3..6, 9..10]);
+        assert_eq!(
+            alloc.allocated_ranges().collect::<Vec<Range<i32>>>(),
+            vec![0..3, 6..9]
+        );
+        // Now request space that can be filled by 3..6 but should be filled by 9..10
+        // because 9..10 is a perfect fit.
+        assert_eq!(alloc.allocate_range(1), Ok(9..10));
+    }
+
+    #[test]
+    fn test_merge_neighbors() {
+        let mut alloc = RangeAllocator::new(0..9);
+        assert_eq!(alloc.allocate_range(3), Ok(0..3));
+        assert_eq!(alloc.allocate_range(3), Ok(3..6));
+        assert_eq!(alloc.allocate_range(3), Ok(6..9));
+        alloc.free_range(0..3);
+        alloc.free_range(6..9);
+        alloc.free_range(3..6);
+        assert_eq!(alloc.free_ranges, vec![0..9]);
+        assert!(alloc.allocated_ranges().eq(std::iter::empty()));
+    }
+}