provide gossipSubParams D values

Author: algorandskiy

network/p2p/pubsub.go

@@ -58,10 +58,24 @@ const TXTopicName = "algotx01"
 
 const incomingThreads = 20 // matches to number wsNetwork workers
 
-func makePubSub(ctx context.Context, cfg config.Local, host host.Host, opts ...pubsub.Option) (*pubsub.PubSub, error) {
-	//defaultParams := pubsub.DefaultGossipSubParams()
+// deriveGossipSubParams derives the gossip sub parameters from the cfg.GossipFanout value
+// by using the same proportions as pubsub defaults - see GossipSubD, GossipSubDlo, etc.
+func deriveGossipSubParams(cfg config.Local) pubsub.GossipSubParams {
+	params := pubsub.DefaultGossipSubParams()
+	params.D = cfg.GossipFanout
+	params.Dlo = params.D - 1
+	if params.Dlo <= 0 {
+		params.Dlo = params.D
+	}
+	params.Dscore = params.D * 2 / 3
+	params.Dout = params.D * 1 / 3
+	return params
+}
 
+func makePubSub(ctx context.Context, cfg config.Local, host host.Host, opts ...pubsub.Option) (*pubsub.PubSub, error) {
+	gossipSubParams := deriveGossipSubParams(cfg)
 	options := []pubsub.Option{
+		pubsub.WithGossipSubParams(gossipSubParams),
 		pubsub.WithPeerScore(&pubsub.PeerScoreParams{
 			DecayInterval: pubsub.DefaultDecayInterval,
 			DecayToZero:   pubsub.DefaultDecayToZero,

network/p2p/pubsub_test.go

@@ -0,0 +1,73 @@
+// Copyright (C) 2019-2025 Algorand, Inc.
+// This file is part of go-algorand
+//
+// go-algorand is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// go-algorand 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with go-algorand.  If not, see <https://www.gnu.org/licenses/>.
+
+package p2p
+
+import (
+	"testing"
+
+	pubsub "github.com/libp2p/go-libp2p-pubsub"
+	"github.com/stretchr/testify/require"
+
+	"github.com/algorand/go-algorand/config"
+	"github.com/algorand/go-algorand/test/partitiontest"
+)
+
+func TestPubsub_GossipSubParamsBasic(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+
+	cfg := config.GetDefaultLocal()
+
+	for _, fanout := range []int{4, 8} {
+		cfg.GossipFanout = fanout
+
+		params := deriveGossipSubParams(cfg)
+
+		require.Equal(t, fanout, params.D)
+		require.Equal(t, fanout-1, params.Dlo)
+		require.Equal(t, fanout*2/3, params.Dscore)
+		require.Equal(t, fanout*1/3, params.Dout)
+
+		// Sanity: other defaults are preserved (not zeroed). Avoid asserting exact values to reduce brittleness.
+		def := pubsub.DefaultGossipSubParams()
+		require.Equal(t, def.HeartbeatInitialDelay, params.HeartbeatInitialDelay)
+		require.Equal(t, def.HistoryLength, params.HistoryLength)
+	}
+}
+
+func TestPubsub_GossipSubParamsEdgeCases(t *testing.T) {
+	partitiontest.PartitionTest(t)
+	t.Parallel()
+
+	// D = 1 => Dlo must not drop below 1
+	cfg := config.GetDefaultLocal()
+	cfg.GossipFanout = 1
+	p := deriveGossipSubParams(cfg)
+	require.Equal(t, 1, p.D)
+	require.Equal(t, 1, p.Dlo)
+	require.Equal(t, 0, p.Dscore)
+	require.Equal(t, 0, p.Dout)
+
+	// D = 0 => keep Dlo = D (0) instead of negative
+	cfg = config.GetDefaultLocal()
+	cfg.GossipFanout = 0
+	p = deriveGossipSubParams(cfg)
+	require.Equal(t, 0, p.D)
+	require.Equal(t, 0, p.Dlo)
+	require.Equal(t, 0, p.Dscore)
+	require.Equal(t, 0, p.Dout)
+}