From 48c2b8e067ef27b512f7e7a882eed563a1c0d626 Mon Sep 17 00:00:00 2001
From: "Brian L. Troutwine" <brian.troutwine@datadoghq.com>
Date: Tue, 15 Oct 2024 10:51:45 -0700
Subject: [PATCH] Allow `Cache` to return a single block

In some cases it is valuable for the block cache to be used without `spin`.
We expose `next_block` to return a `Block` reference as soon as one is
available, blocking the callers meanwhile.

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>
---
 lading_payload/src/block.rs | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/lading_payload/src/block.rs b/lading_payload/src/block.rs
index fd1783bff..59605d519 100644
--- a/lading_payload/src/block.rs
+++ b/lading_payload/src/block.rs
@@ -342,6 +342,23 @@ impl Cache {
             },
         }
     }
+
+    /// Return a `Block` from the `Cache`
+    ///
+    /// This is a blocking function that returns a single `Block` instance as
+    /// soon as one is ready, blocking the caller until one is available.
+    pub fn next_block(&mut self) -> &Block {
+        match self {
+            Self::Fixed {
+                ref mut idx,
+                blocks,
+            } => {
+                let block = &blocks[*idx];
+                *idx = (*idx + 1) % blocks.len();
+                block
+            }
+        }
+    }
 }
 
 /// Construct a new block cache of form defined by `serializer`.