From 3f9aa8d8fa328fee897d0295fb8024f1cf67c9f4 Mon Sep 17 00:00:00 2001
From: Anton Kaliaev <anton.kalyaev@gmail.com>
Date: Thu, 8 Feb 2018 13:09:46 +0400
Subject: [PATCH] document that msgBytes in p2p/connection change

---
 p2p/base_reactor.go    | 5 ++++-
 p2p/conn/connection.go | 8 ++------
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/p2p/base_reactor.go b/p2p/base_reactor.go
index 8217d46b..f0dd1414 100644
--- a/p2p/base_reactor.go
+++ b/p2p/base_reactor.go
@@ -23,7 +23,10 @@ type Reactor interface {
 
 	// Receive is called when msgBytes is received from peer.
 	//
-	// CONTRACT: msgBytes are not nil
+	// NOTE reactor can not keep msgBytes around after Receive completes without
+	// copying.
+	//
+	// CONTRACT: msgBytes are not nil.
 	Receive(chID byte, peer Peer, msgBytes []byte)
 }
 
diff --git a/p2p/conn/connection.go b/p2p/conn/connection.go
index 6b491250..7727ee32 100644
--- a/p2p/conn/connection.go
+++ b/p2p/conn/connection.go
@@ -679,7 +679,8 @@ func writeMsgPacketTo(packet msgPacket, w io.Writer, n *int, err *error) {
 	wire.WriteBinary(packet, w, n, err)
 }
 
-// Handles incoming msgPackets. Returns a msg bytes if msg is complete.
+// Handles incoming msgPackets. It returns a message bytes if message is
+// complete. NOTE message bytes may change on next call to recvMsgPacket.
 // Not goroutine-safe
 func (ch *Channel) recvMsgPacket(packet msgPacket) ([]byte, error) {
 	ch.Logger.Debug("Read Msg Packet", "conn", ch.conn, "packet", packet)
@@ -688,11 +689,6 @@ func (ch *Channel) recvMsgPacket(packet msgPacket) ([]byte, error) {
 	}
 	ch.recving = append(ch.recving, packet.Bytes...)
 	if packet.EOF == byte(0x01) {
-		// TODO: document that these returned msgBytes will change under you after Receive finishes.
-		// TODO: document it in the Reactor interface especially - implementations of a Reactor
-		// can not keep these bytes around after the Receive completes without copying!
-		// In general that's fine, because the first thing we do is unmarshal into a msg type and then
-		// we never use the bytes again
 		msgBytes := ch.recving
 
 		// clear the slice without re-allocating.