runtime: add a method into_segments to AggregatedBytes (#2525)

* start, add a method to AggregatedBytes called into_segments

* update CHANGELOG.next.toml

Author: do-not-use-parker-timmerman

CHANGELOG.next.toml

@@ -74,3 +74,9 @@ message = "Add support for omitting session token in canonical requests for SigV
 references = ["smithy-rs#2473"]
 meta = { "breaking" = false, "tada" = false, "bug" = false }
 author = "martinjlowm"
+
+[[aws-sdk-rust]]
+message = "Add `into_segments` method to `AggregatedBytes`, for zero-copy conversions."
+references = ["smithy-rs#2525"]
+meta = { "breaking" = false, "tada" = false, "bug" = false }
+author = "parker-timmerman"

rust-runtime/aws-smithy-http/src/byte_stream.rs

@@ -477,6 +477,11 @@ impl AggregatedBytes {
         self.0.copy_to_bytes(self.0.remaining())
     }
 
+    /// Convert this buffer into an [`Iterator`] of underlying non-contiguous segments of [`Bytes`]
+    pub fn into_segments(self) -> impl Iterator<Item = Bytes> {
+        self.0.into_inner().into_iter()
+    }
+
     /// Convert this buffer into a `Vec<u8>`
     pub fn to_vec(self) -> Vec<u8> {
         self.0