Reduce unnecessary memory allocations

TODO.md

@@ -35,7 +35,7 @@
 - [ ] (minor) rename keys to ids in `LeaseEntry`, or actually put keys in there. either way
 - [X] (minor) make `add_available_item_from_parts` wrap `add_available_items_from_parts`, not the other way around
 - [ ] (minor) use a mockable clock when generating uuidv7s
-- [ ] (perf) reduce unnecessary allocs, such as when copying data or allocating buffers. some is called out in code comments
+- [X] (perf) reduce unnecessary allocs, such as when copying data or allocating buffers. some is called out in code comments
 - [ ] (perf) sort the keys in `LeaseEntry` so we can do bsearch on them
 - [ ] (major) ensure `extend` doesnt create multiple index entries for the same lease.
 - [ ] (perf) add lease expiry index key to `LeaseEntry` so we don't have to do scans to find it when extending

src/server.rs

@@ -116,9 +116,9 @@ impl crate::protocol::queue::Server for Server {
 
         // Generate ids upfront and copy request data into owned memory so we can move
         // it into a blocking task (capnp readers are not Send).
-        let ids: Vec<Vec<u8>> = items
+        let ids: Vec<[u8; 16]> = items
             .iter()
-            .map(|_| uuid::Uuid::now_v7().as_bytes().to_vec())
+            .map(|_| uuid::Uuid::now_v7().into_bytes())
             .collect();
 
         let items_owned = items
@@ -135,8 +135,6 @@ impl crate::protocol::queue::Server for Server {
 
         let storage = Arc::clone(&self.storage);
         let notify = Arc::clone(&self.notify);
-        let ids_for_resp = ids.clone();
-
         Promise::from_future(async move {
             // Offload RocksDB work to the blocking thread pool.
             let iter = ids
@@ -150,11 +148,8 @@ impl crate::protocol::queue::Server for Server {
             }
 
             // Build the response on the RPC thread.
-            let mut ids_builder = results
-                .get()
-                .init_resp()
-                .init_ids(ids_for_resp.len() as u32);
-            for (i, id) in ids_for_resp.iter().enumerate() {
+            let mut ids_builder = results.get().init_resp().init_ids(ids.len() as u32);
+            for (i, id) in ids.iter().enumerate() {
                 ids_builder.set(i as u32, id);
             }
             Ok(())

src/storage.rs

@@ -265,11 +265,10 @@ impl Storage {
 
         // Build the lease entry.
         let lease_entry = build_lease_entry_message(lease_validity_secs, &polled_items)?;
-        let mut lease_entry_bs = Vec::with_capacity(lease_entry.size_in_words() * 8); // TODO: avoid allocation
-        serialize::write_message(&mut lease_entry_bs, &lease_entry)?;
-
+        let mut lease_buf = Vec::with_capacity(lease_entry.size_in_words() * 8);
+        serialize::write_message(&mut lease_buf, &lease_entry)?;
         // Write the lease entry and its expiry index
-        txn.put(lease_key.as_ref(), &lease_entry_bs)?;
+        txn.put(lease_key.as_ref(), &lease_buf)?;
         txn.put(lease_expiry_index_key.as_ref(), lease_key.as_ref())?;
 
         drop(snapshot);
@@ -343,7 +342,7 @@ impl Storage {
                 out_keys.set(new_idx as u32, k);
                 new_idx += 1;
             }
-            let mut buf = Vec::with_capacity(msg.size_in_words() * 8); // TODO: reduce allocs
+            let mut buf = Vec::with_capacity(msg.size_in_words() * 8);
             serialize::write_message(&mut buf, &msg)?;
             txn.put(lease_key.as_ref(), &buf)?;
         }