feat: add capnp

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/sq-storage/src/object_store/layout.rs

@@ -0,0 +1,93 @@
+/// S3 key layout for shipped WAL segments.
+///
+/// Format: `{cluster_id}/{topic}/{partition}/{base_offset:020}-{end_offset:020}.sqseg`
+///
+/// The 020 zero-padding ensures lexicographic ordering matches offset ordering.
+pub fn segment_key(
+    cluster_id: &str,
+    topic: &str,
+    partition: u32,
+    base_offset: u64,
+    end_offset: u64,
+) -> String {
+    format!(
+        "{}/{}/{}/{:020}-{:020}.sqseg",
+        cluster_id, topic, partition, base_offset, end_offset
+    )
+}
+
+/// Parse a segment key back into its components.
+/// Returns (cluster_id, topic, partition, base_offset, end_offset).
+pub fn parse_segment_key(key: &str) -> Option<(String, String, u32, u64, u64)> {
+    let parts: Vec<&str> = key.split('/').collect();
+    if parts.len() != 4 {
+        return None;
+    }
+
+    let cluster_id = parts[0].to_string();
+    let topic = parts[1].to_string();
+    let partition: u32 = parts[2].parse().ok()?;
+
+    let filename = parts[3].strip_suffix(".sqseg")?;
+    let offsets: Vec<&str> = filename.split('-').collect();
+    if offsets.len() != 2 {
+        return None;
+    }
+
+    let base_offset: u64 = offsets[0].parse().ok()?;
+    let end_offset: u64 = offsets[1].parse().ok()?;
+
+    Some((cluster_id, topic, partition, base_offset, end_offset))
+}
+
+/// S3 key prefix for listing segments of a topic-partition.
+pub fn topic_partition_prefix(cluster_id: &str, topic: &str, partition: u32) -> String {
+    format!("{}/{}/{}/", cluster_id, topic, partition)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_segment_key_format() {
+        let key = segment_key("cluster-1", "orders", 0, 0, 999);
+        assert_eq!(
+            key,
+            "cluster-1/orders/0/00000000000000000000-00000000000000000999.sqseg"
+        );
+    }
+
+    #[test]
+    fn test_segment_key_lexicographic_order() {
+        let k1 = segment_key("c", "t", 0, 0, 999);
+        let k2 = segment_key("c", "t", 0, 1000, 1999);
+        let k3 = segment_key("c", "t", 0, 2000, 2999);
+        assert!(k1 < k2);
+        assert!(k2 < k3);
+    }
+
+    #[test]
+    fn test_parse_segment_key() {
+        let key = segment_key("cluster-1", "orders", 2, 1000, 1999);
+        let parsed = parse_segment_key(&key).unwrap();
+        assert_eq!(parsed.0, "cluster-1");
+        assert_eq!(parsed.1, "orders");
+        assert_eq!(parsed.2, 2);
+        assert_eq!(parsed.3, 1000);
+        assert_eq!(parsed.4, 1999);
+    }
+
+    #[test]
+    fn test_parse_invalid_key() {
+        assert!(parse_segment_key("invalid").is_none());
+        assert!(parse_segment_key("a/b/c").is_none());
+        assert!(parse_segment_key("a/b/c/d.txt").is_none());
+    }
+
+    #[test]
+    fn test_topic_partition_prefix() {
+        let prefix = topic_partition_prefix("cluster-1", "orders", 0);
+        assert_eq!(prefix, "cluster-1/orders/0/");
+    }
+}