From 0bbf38141a6498f661d6c956c9f45066c312d90e Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Fri, 20 Oct 2017 21:19:25 -0400
Subject: [PATCH] blockchain/pool: some comments and small changes

---
 blockchain/pool.go    | 23 ++++++++++++++++++++---
 blockchain/reactor.go |  4 ++--
 p2p/pex_reactor.go    |  1 +
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/blockchain/pool.go b/blockchain/pool.go
index aac4c77c3..348ba09b3 100644
--- a/blockchain/pool.go
+++ b/blockchain/pool.go
@@ -11,11 +11,25 @@ import (
 	"github.com/tendermint/tmlibs/log"
 )
 
+/*
+
+eg, L = latency = 0.1s
+	P = num peers = 10
+	FN = num full nodes
+	BS = 1kB block size
+	CB = 1 Mbit/s = 128 kB/s
+	CB/P = 12.8 kB
+	B/S = CB/P/BS = 12.8 blocks/s
+
+	12.8 * 0.1 = 1.28 blocks on conn
+
+*/
+
 const (
 	requestIntervalMS         = 250
 	maxTotalRequesters        = 300
 	maxPendingRequests        = maxTotalRequesters
-	maxPendingRequestsPerPeer = 75
+	maxPendingRequestsPerPeer = 10
 	minRecvRate               = 10240 // 10Kb/s
 )
 
@@ -186,15 +200,16 @@ func (pool *BlockPool) PopRequest() {
 // Remove the peer and redo request from others.
 func (pool *BlockPool) RedoRequest(height int) {
 	pool.mtx.Lock()
+	defer pool.mtx.Unlock()
+
 	request := pool.requesters[height]
-	pool.mtx.Unlock()
 
 	if request.block == nil {
 		cmn.PanicSanity("Expected block to be non-nil")
 	}
 	// RemovePeer will redo all requesters associated with this peer.
 	// TODO: record this malfeasance
-	pool.RemovePeer(request.peerID)
+	pool.removePeer(request.peerID)
 }
 
 // TODO: ensure that blocks come in order for each peer.
@@ -204,6 +219,8 @@ func (pool *BlockPool) AddBlock(peerID string, block *types.Block, blockSize int
 
 	requester := pool.requesters[block.Height]
 	if requester == nil {
+		// a block we didn't expect.
+		// TODO:if height is too far ahead, punish peer
 		return
 	}
 
diff --git a/blockchain/reactor.go b/blockchain/reactor.go
index 6ff010038..b46ad40fa 100644
--- a/blockchain/reactor.go
+++ b/blockchain/reactor.go
@@ -221,9 +221,9 @@ FOR_LOOP:
 			// ask for status updates
 			go bcR.BroadcastStatusRequest()
 		case <-switchToConsensusTicker.C:
-			height, numPending, _ := bcR.pool.GetStatus()
+			height, numPending, lenRequesters := bcR.pool.GetStatus()
 			outbound, inbound, _ := bcR.Switch.NumPeers()
-			bcR.Logger.Info("Consensus ticker", "numPending", numPending, "total", len(bcR.pool.requesters),
+			bcR.Logger.Info("Consensus ticker", "numPending", numPending, "total", lenRequesters,
 				"outbound", outbound, "inbound", inbound)
 			if bcR.pool.IsCaughtUp() {
 				bcR.Logger.Info("Time to switch to consensus reactor!", "height", height)
diff --git a/p2p/pex_reactor.go b/p2p/pex_reactor.go
index 69ab55cc9..54c2d06b5 100644
--- a/p2p/pex_reactor.go
+++ b/p2p/pex_reactor.go
@@ -139,6 +139,7 @@ func (r *PEXReactor) Receive(chID byte, src Peer, msgBytes []byte) {
 	switch msg := msg.(type) {
 	case *pexRequestMessage:
 		// src requested some peers.
+		// NOTE: we might send an empty selection
 		r.SendAddrs(src, r.book.GetSelection())
 	case *pexAddrsMessage:
 		// We received some peer addresses from src.