docs(tvix/store/protos): add docstring for Directory::digest() r/5778

Change-Id: I361dbca444a267fea28cd212d563ee2d03497c16
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7952
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

1 files changed, 2 insertions, 0 deletions

diff --git a/tvix/store/src/proto.rs b/tvix/store/src/proto.rs
index 706041d6a3..0b4e11bebf 100644
--- a/tvix/store/src/proto.rs
+++ b/tvix/store/src/proto.rs
@@ -189,6 +189,8 @@ impl Directory {
                 .fold(0, |acc: u32, e| (acc + 1 + e.size) as u32)
     }
 
+    /// Calculates the digest of a Directory, which is the blake3 hash of a
+    /// Directory protobuf message, serialized in protobuf canonical form.
     pub fn digest(&self) -> Vec<u8> {
         let mut hasher = blake3::Hasher::new();