put remake content into blobs

1 files changed, 21 insertions, 4 deletions

diff --git a/src/swarm/blob.rs b/src/swarm/blob.rs
index 6ff1618..8c891ae 100644
--- a/src/swarm/blob.rs
+++ b/src/swarm/blob.rs
@@ -2,8 +2,9 @@
 //!
 //! Large transfers can't go in one Mycelium message (it must arrive within Mycelium's
 //! five-minute deadline), and a blob every node holds identically can come from many
-//! of them. Today the only kind of blob is an Automerge change by its hash, e.g. an
-//! epoch's snapshot change, which every node on that epoch holds byte for byte.
+//! of them. A blob is an Automerge change by its hash (e.g. an epoch's snapshot change,
+//! which every node on that epoch holds byte for byte), or content by its BLAKE3 hash
+//! (e.g. the new document of a `replace` or `import` remake).
 //!
 //! * Serving: a request without chunks gets the manifest (size, chunk size, a BLAKE3
 //!   hash per chunk); one with chunks gets each chunk as a message of its own. A node
@@ -62,7 +63,7 @@ pub(crate) struct Blobs {
 }
 
 struct Prepared {
-    bytes: Vec<u8>,
+    bytes: Arc<Vec<u8>>,
     hashes: Vec<[u8; 32]>,
 }
 
@@ -152,8 +153,10 @@ async fn prepare(state: &AppState, id: BlobId) -> Option<Arc<Prepared>> {
             })
             .await
             .ok()
-            .flatten()?
+            .flatten()
+            .map(Arc::new)?
         }
+        BlobId::Content(hash) => state.remake.content(&hash)?,
     };
     let chunk_size = state.blobs.chunk_size;
     let prepared = tokio::task::spawn_blocking(move || {
@@ -454,6 +457,20 @@ fn expected_len(manifest: &Manifest, slot: usize) -> usize {
 }
 
 /// Downloads change `hash` from `peers` and checks it.
+/// Downloads the content with BLAKE3 hash `hash` from `peers` and checks it.
+pub(crate) async fn fetch_content(
+    state: &AppState,
+    hash: [u8; 32],
+    peers: Vec<String>,
+) -> Result<Vec<u8>> {
+    let id = BlobId::Content(hash);
+    let bytes = fetch(state, id, peers).await?;
+    if *blake3::hash(&bytes).as_bytes() != hash {
+        bail!("downloaded {id} doesn't match its hash");
+    }
+    Ok(bytes)
+}
+
 pub(crate) async fn fetch_change(
     state: &AppState,
     hash: ChangeHash,