joroKr21 commented on code in PR #5222:
URL: https://github.com/apache/arrow-rs/pull/5222#discussion_r1571070089
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object_store/src/util.rs:
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@@ -167,6 +173,119 @@ fn merge_ranges(ranges: &[std::ops::Range<usize>],
coalesce: usize) -> Vec<std::
ret
}
+/// Request only a portion of an object's bytes
+///
+/// These can be created from [usize] ranges, like
+///
+/// ```rust
+/// # use object_store::GetRange;
+/// let range1: GetRange = (50..150).into();
+/// let range2: GetRange = (50..=150).into();
+/// let range3: GetRange = (50..).into();
+/// let range4: GetRange = (..150).into();
+/// ```
+///
+/// Implementations may wish to inspect [`GetResult`] for the exact byte
+/// range returned.
+///
+/// [`GetResult`]: crate::GetResult
+#[derive(Debug, PartialEq, Eq, Clone)]
+pub enum GetRange {
+ /// Request a specific range of bytes
+ ///
+ /// If the given range is zero-length or starts after the end of the
object,
+ /// an error will be returned. Additionally, if the range ends after the
end
+ /// of the object, the entire remainder of the object will be returned.
+ /// Otherwise, the exact requested range will be returned.
+ Bounded(Range<usize>),
+ /// Request all bytes starting from a given byte offset
+ Offset(usize),
+ /// Request up to the last n bytes
+ Suffix(usize),
+}
+
+#[derive(Debug, Snafu)]
+pub(crate) enum InvalidGetRange {
+ #[snafu(display(
+ "Wanted range starting at {requested}, but object was only {length}
bytes long"
+ ))]
+ StartTooLarge { requested: usize, length: usize },
+
+ #[snafu(display("Range started at {start} and ended at {end}"))]
+ Inconsistent { start: usize, end: usize },
+}
+
+impl GetRange {
+ pub(crate) fn is_valid(&self) -> Result<(), InvalidGetRange> {
+ match self {
+ Self::Bounded(r) if r.end <= r.start => {
+ return Err(InvalidGetRange::Inconsistent {
+ start: r.start,
+ end: r.end,
+ });
+ }
+ _ => (),
+ };
+ Ok(())
+ }
+
+ /// Convert to a [`Range`] if valid.
+ pub(crate) fn as_range(&self, len: usize) -> Result<Range<usize>,
InvalidGetRange> {
Review Comment:
Why not make this public? It looks like this is needed by anyone
implementing an `ObjectStore`
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