From 44e36596c9c0e8d606ffb89b6fa171b3ff04f53d Mon Sep 17 00:00:00 2001
From: Robert Habermeier <rphmeier@gmail.com>
Date: Sun, 6 Nov 2016 19:04:30 +0100
Subject: [PATCH] buffer flow scaffolding

---
 ethcore/light/src/lib.rs             |  4 +--
 ethcore/light/src/net/buffer_flow.rs | 42 ++++++++++++++++++++++++++++
 ethcore/light/src/net/mod.rs         |  4 +--
 3 files changed, 46 insertions(+), 4 deletions(-)
 create mode 100644 ethcore/light/src/net/buffer_flow.rs

diff --git a/ethcore/light/src/lib.rs b/ethcore/light/src/lib.rs
index 1bfb6569a..63586f5a2 100644
--- a/ethcore/light/src/lib.rs
+++ b/ethcore/light/src/lib.rs
@@ -25,8 +25,8 @@
 //! low-latency applications, but perfectly suitable for simple everyday
 //! use-cases like sending transactions from a personal account.
 //!
-//! It starts by performing a header-only sync, verifying every header in
-//! the chain.
+//! It starts by performing a header-only sync, verifying random samples
+//! of members of the chain to varying degrees.
 
 pub mod client;
 pub mod net;
diff --git a/ethcore/light/src/net/buffer_flow.rs b/ethcore/light/src/net/buffer_flow.rs
new file mode 100644
index 000000000..ece9f7057
--- /dev/null
+++ b/ethcore/light/src/net/buffer_flow.rs
@@ -0,0 +1,42 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! LES buffer flow management.
+//!
+//! Every request in the LES protocol leads to a reduction
+//! of the requester's buffer value as a rate-limiting mechanism.
+//! This buffer value will recharge at a set rate.
+//!
+//! This module provides an interface for configuration of buffer
+//! flow costs and recharge rates.
+
+use request::{self, Request};
+
+/// Manages buffer flow costs for specific requests.
+pub struct FlowManager;
+
+impl FlowManager {
+	/// Estimate the maximum cost of this request.
+	pub fn estimate_cost(&self, req: &request::Request) -> usize {
+		unimplemented!()
+	}
+
+	/// Get an exact cost based on request kind and amount of requests fulfilled.
+	pub fn exact_cost(&self, kind: request::Kind, amount: usize) -> usize {
+		unimplemented!()
+	}
+}
+
diff --git a/ethcore/light/src/net/mod.rs b/ethcore/light/src/net/mod.rs
index 390c6a35b..efbc391e1 100644
--- a/ethcore/light/src/net/mod.rs
+++ b/ethcore/light/src/net/mod.rs
@@ -31,6 +31,8 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 use provider::Provider;
 use request::{self, Request};
 
+mod buffer_flow;
+
 const TIMEOUT: TimerToken = 0;
 const TIMEOUT_INTERVAL_MS: u64 = 1000;
 
@@ -40,8 +42,6 @@ const PROTOCOL_VERSION: u32 = 1;
 // TODO [rob] make configurable.
 const PROTOCOL_ID: [u8; 3] = *b"les";
 
-// TODO [rob] Buffer flow.
-
 // packet ID definitions.
 mod packet {
 	// the status packet.