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fix: increase handshake channel capacity from 32 to 1024 #59

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Merged
jacderida merged 1 commit into from
Apr 14, 2026
Merged

fix: increase handshake channel capacity from 32 to 1024 #59

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16 changes: 12 additions & 4 deletions src/nat_traversal_api.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1474,8 +1474,12 @@ impl NatTraversalEndpoint {
let (nack_tx, nack_rx) = mpsc::unbounded_channel();
inner_endpoint.set_nack_tx(nack_tx);

// Channel for background handshake completion (persistent across accept calls)
let (hs_tx, hs_rx) = mpsc::channel(32);
// Channel for background handshake completion (persistent across accept calls).
// Capacity 1024: the consumer (accept_connection_direct → P2pEndpoint::accept)
// can stall briefly under write-lock contention in saorsa-core's accept loop.
// A small buffer (32) caused the pipeline to back up after 15+ hours in a
// 1000-node testnet, blocking all new connection handoffs.
let (hs_tx, hs_rx) = mpsc::channel(1024);
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@greptile-apps greptile-apps Bot Apr 14, 2026

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P2 Capacity duplicated in two constructors

The value 1024 appears at both line 1482 and line 1958. A named constant would make future adjustments atomic and signal intent:

/// Buffer for completed handshakes. Sized above the peak backlog observed
/// in the ant-rc-18 testnet (1 079 connections) so transient consumer
/// stalls don't block the accept loop.
const HANDSHAKE_CHANNEL_CAPACITY: usize = 1024;

Then mpsc::channel(HANDSHAKE_CHANNEL_CAPACITY) at both sites.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: src/nat_traversal_api.rs
Line: 1482

Comment:
**Capacity duplicated in two constructors**

The value `1024` appears at both line 1482 and line 1958. A named constant would make future adjustments atomic and signal intent:

```rust
/// Buffer for completed handshakes. Sized above the peak backlog observed
/// in the ant-rc-18 testnet (1 079 connections) so transient consumer
/// stalls don't block the accept loop.
const HANDSHAKE_CHANNEL_CAPACITY: usize = 1024;
```

Then `mpsc::channel(HANDSHAKE_CHANNEL_CAPACITY)` at both sites.

How can I resolve this? If you propose a fix, please make it concise.


// Compute local peer ID = BLAKE3(public_key_spki) for
// deterministic simultaneous-connect tie-breaking.
Expand Down Expand Up @@ -1946,8 +1950,12 @@ impl NatTraversalEndpoint {
let (nack_tx, nack_rx) = mpsc::unbounded_channel();
inner_endpoint.set_nack_tx(nack_tx);

// Channel for background handshake completion (persistent across accept calls)
let (hs_tx, hs_rx) = mpsc::channel(32);
// Channel for background handshake completion (persistent across accept calls).
// Capacity 1024: the consumer (accept_connection_direct → P2pEndpoint::accept)
// can stall briefly under write-lock contention in saorsa-core's accept loop.
// A small buffer (32) caused the pipeline to back up after 15+ hours in a
// 1000-node testnet, blocking all new connection handoffs.
let (hs_tx, hs_rx) = mpsc::channel(1024);

// Compute local peer ID = BLAKE3(public_key_spki) for
// deterministic simultaneous-connect tie-breaking.
Expand Down
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