9243d0c0

refactor: egress_cap is an Egress tunable, not a wire agreement

a73x 2026-08-12 18:27

Commit message

refactor: egress_cap is an Egress tunable, not a wire agreement

The wire-constants banner promises numbers both ends must spell alike, and
egress_cap is not one: it sizes a LOCAL ring, while the windows a peer
actually respects arrive in the transport params. Two ends with different
ring sizes interoperate — so the constant belongs with the ring it sizes.

Moved to the top of the Egress section, above `Egress` itself. Doc unchanged;
line-multiset diff shows nothing added and nothing dropped.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/quic.zig

Old		New
@@ -53,12 +53,6 @@ pub const psk_identity: [*:0]const u8 = "mux";
53	pub const psk_ciphersuite: [*:0]const u8 = "TLS13-AES128-GCM-SHA256";	53	pub const psk_ciphersuite: [*:0]const u8 = "TLS13-AES128-GCM-SHA256";
54	pub const alpn = "\x03mux";	54	pub const alpn = "\x03mux";
55		55
56	/// How many outbound bytes one connection may hold. Sized to the stream
57	/// window the peer advertises, because holding much more than the peer will
58	/// let us send buys nothing: past this the daemon's own `pending_cap` is the
59	/// right place for the backlog to sit and be judged.
60	pub const egress_cap = 256 * 1024;
61
62	// ---------------------------------------------------------------------------	56	// ---------------------------------------------------------------------------
63	// The pre-shared key	57	// The pre-shared key
64	// ---------------------------------------------------------------------------	58	// ---------------------------------------------------------------------------
@@ -239,6 +233,12 @@ test "Key.load: refuses a permissive mode, a missing file, and a bad length" {
239	// Egress: the ring, and what one writev_stream return means for it	233	// Egress: the ring, and what one writev_stream return means for it
240	// ---------------------------------------------------------------------------	234	// ---------------------------------------------------------------------------
241		235
		236	/// How many outbound bytes one connection may hold. Sized to the stream
		237	/// window the peer advertises, because holding much more than the peer will
		238	/// let us send buys nothing: past this the daemon's own `pending_cap` is the
		239	/// right place for the backlog to sit and be judged.
		240	pub const egress_cap = 256 * 1024;
		241
242	/// Outbound stream bytes, in a ring that never moves a byte once written.	242	/// Outbound stream bytes, in a ring that never moves a byte once written.
243	///	243	///
244	/// A ring rather than a growable buffer, because ngtcp2 does NOT copy stream	244	/// A ring rather than a growable buffer, because ngtcp2 does NOT copy stream