perf(chunk): hold ChunkPutRequest content as Bytes for zero-copy fan-out#6
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perf(chunk): hold ChunkPutRequest content as Bytes for zero-copy fan-out#6jacderida wants to merge 1 commit into
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Replace `content: Vec<u8>` with `content: bytes::Bytes` on ChunkPutRequest. Wire format is unchanged — Bytes serialises as a byte sequence under postcard/serde, identical to Vec<u8> — but the in-memory representation is now refcounted, so callers that send the same chunk to multiple peers (notably close-group replication) share a single backing buffer instead of deep-copying the 4 MB payload per peer. Heaptrack against a 20 MB upload on a release ant binary showed the client's peak heap dominated by RawVecInner::finish_grow calls in ChunkPutRequest construction, with 168 MB consumed via ChunkMessage::encode → chunk_put_to_close_group. The fan-out path was running `content.to_vec()` once per recipient at chunk.rs:173, which the new Bytes-typed field eliminates from the caller side. This commit is the protocol-side half of the fix; the ant-client side drops the `to_vec()` in a follow-up PR. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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`ChunkPutRequest.content` is now `bytes::Bytes` upstream (WithAutonomi/ant-protocol#6) so that close-group fan-out on the client side can share one refcounted buffer across N peer sends instead of deep-copying the 4 MB chunk per peer. ant-node is on the receiving side of that wire format. The storage handler's existing reads — `.len()`, `compute_address(&request.content)`, `self.storage.put(&address, &request.content)` — all coerce `Bytes`/`&Bytes` to `&[u8]` transparently, so the production hot path needs no change. Two adjustments cover the remaining call sites: - `FreshWriteEvent.data: Vec<u8>` still owns the chunk for replication fan-out. Materialise once at the boundary via `request.content.to_vec()` on the success path. This is one copy on a node that has already accepted the chunk — node VMs aren't memory-constrained the way the client VMs are. Propagating `Bytes` deeper into the replication path is a worthwhile follow-up but out of scope for this fix. - Test sites that constructed `ChunkPutRequest::new(addr, content.to_vec())` from byte-string literals now use `Bytes::copy_from_slice(content)`, and the one site with an owned `Vec<u8>` uses `Bytes::from(content)`. [patch.crates-io] and [patch."https://github.com/WithAutonomi/ant-protocol"] override the dep with the jacderida/ant-protocol perf branch commit so ant-node builds against the new field type both from `main` (crates.io) and from testnet branches like `fix/stability-improvements` (which resolve ant-protocol via saorsa-core's git-source patch). The pin should be removed once a crates.io release including the ant-protocol change is published. Test plan --------- - `cargo check --lib` — clean - `cargo test --lib storage::handler` — 14/14 pass Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
ChunkPutRequest.content: Vec<u8>withcontent: bytes::Bytes.bytescrate'sserdefeature soBytesserialises identically toVec<u8>on the wire (both becomeseq[u8]under postcard).ChunkPutRequest::new/with_paymentsignatures and the two existing tests.Why
A heaptrack capture against a release
antbinary uploading a 20 MB file shows peak heap pinned to ~285 MB inalloc::raw_vec::RawVecInner::finish_grow, with the dominant call chain landing atChunkMessage::encode→chunk_put_to_close_group. The fan-out path atant-client/ant-core/src/data/client/chunk.rs:173does:The
contentparameter is already a refcountedbytes::Bytes, butto_vec()deep-copies the entire 4 MB chunk into a freshVec<u8>— once per recipient. WithCLOSE_GROUP_MAJORITY ≈ 5peers and the AIMD store cap at 64, peak in-flight chunk-content can reach ~2.5 GB on a single client, which exceeds the 4 GB VM budget once DHT/QUIC/etc. overhead is added.Switching
contenttoBytesremoves the requirement for the caller to copy. The ant-client follow-up PR drops theto_vec()and passes theBytesstraight through, so each peer's spawned task shares a single 4 MB backing buffer via refcount instead of holding N independent copies.Wire compatibility
Identical. Under postcard + serde, both
Vec<u8>andbytes::Bytesare encoded as a varint length followed by the raw bytes. A mixed network of old and new clients/servers will interoperate.Test plan
cargo check --all-featurescleancargo test --lib chunk— all 17 chunk tests pass (the two ChunkPutRequest tests updated to constructBytes::from_static(...))WithAutonomi/ant-client, which patches this branch in via[patch.crates-io]and drops theto_vec(). ant-node also readsrequest.contentasVec<u8>instorage/handler.rsand will need a matching update before its next release.🤖 Generated with Claude Code