p2p/protocols: comments for accounting simulation

p2p/protocols/accounting_simulation_test.go

@@ -1,3 +1,19 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library 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 Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
 package protocols
 
 import (
@@ -27,8 +43,8 @@ const (
 )
 
 var (
-	nodes    = flag.Int("nodes", 30, "number of nodes to create (default 10)")
-	msgs     = flag.Int("msgs", 100, "number of messages sent by node (default 10)")
+	nodes    = flag.Int("nodes", 30, "number of nodes to create (default 30)")
+	msgs     = flag.Int("msgs", 100, "number of messages sent by node (default 100)")
 	loglevel = flag.Int("loglevel", 0, "verbosity of logs")
 	rawlog   = flag.Bool("rawlog", false, "remove terminal formatting from logs")
 )
@@ -39,13 +55,24 @@ func init() {
 	log.Root().SetHandler(log.LvlFilterHandler(log.Lvl(*loglevel), log.StreamHandler(colorable.NewColorableStderr(), log.TerminalFormat(!*rawlog))))
 }
 
+//TestAccountingSimulation runs a p2p/simulations simulation
+//It creates a *nodes number of nodes, connects each one with each other,
+//then sends out a random selection of messages up to *msgs amount of messages
+//from the test protocol spec.
+//The spec has some accounted messages defined through the Prices interface.
+//The test does accounting for all the message exchanged, and then checks
+//that every node has the same balance with a peer, but with opposite signs.
+//Balance(AwithB) = 0 - Balance(BwithA) or Abs|Balance(AwithB)| == Abs|Balance(BwithA)|
 func TestAccountingSimulation(t *testing.T) {
+	//setup the balances objects for every node
 	bal := newBalances(*nodes)
+	//define the node.Service for this test
 	services := adapters.Services{
 		"accounting": func(ctx *adapters.ServiceContext) (node.Service, error) {
 			return bal.newNode(), nil
 		},
 	}
+	//setup the simulation
 	adapter := adapters.NewSimAdapter(services)
 	net := simulations.NewNetwork(adapter, &simulations.NetworkConfig{DefaultService: "accounting"})
 	defer net.Shutdown()
@@ -57,6 +84,8 @@ func TestAccountingSimulation(t *testing.T) {
 		// wait for all of them to arrive
 		bal.wg.Wait()
 		// then trigger a check
+		// the selected node for the trigger is irrelevant,
+		// we just want to trigger the end of the simulation
 		trigger <- net.Nodes[0].ID()
 	}()
 
@@ -102,10 +131,6 @@ func TestAccountingSimulation(t *testing.T) {
 		},
 	})
 
-	// check if balance matrix is symmetric
-	if err := bal.symmetric(); err != nil {
-		t.Fatal(err)
-	}
 	if result.Error != nil {
 		t.Fatal(result.Error)
 	}
@@ -116,11 +141,19 @@ func TestAccountingSimulation(t *testing.T) {
 	}
 }
 
+// matrix is a matrix of nodes and its balances
+// matrix is in fact a linear array of size n*n,
+// so the balance for any node A with B is at index
+// A*n + B, while the balance of node B with A is at
+// B*n + A
+// (n entries in the array will not be filled -
+//  the balance of a node with itself)
 type matrix struct {
-	n int
-	m []int64
+	n int     //number of nodes
+	m []int64 //array of balances
 }
 
+// create a new matrix
 func newMatrix(n int) *matrix {
 	return &matrix{
 		n: n,
@@ -128,16 +161,24 @@ func newMatrix(n int) *matrix {
 	}
 }
 
+// called from the testBalance's Add accounting function: register balance change
 func (m *matrix) add(i, j int, v int64) error {
+	// index for the balance of local node i with remote nodde j is
+	// i * number of nodes + remote node
 	mi := i*m.n + j
+	// register that balance
 	m.m[mi] += v
 	return nil
 }
 
+// check that the balances are symmetric:
+// balance of node i with node j is the same as j with i but with inverted signs
 func (m *matrix) symmetric() error {
+	//iterate all nodes
 	for i := 0; i < m.n; i++ {
+		//iterate starting +1
 		for j := i + 1; j < m.n; j++ {
-			log.Warn("bal", "1", i, "2", j, "i,j", m.m[i*m.n+j], "j,i", m.m[j*m.n+i])
+			log.Debug("bal", "1", i, "2", j, "i,j", m.m[i*m.n+j], "j,i", m.m[j*m.n+i])
 			if m.m[i*m.n+j] != -m.m[j*m.n+i] {
 				return fmt.Errorf("value mismatch. m[%v, %v] = %v; m[%v, %v] = %v", i, j, m.m[i*m.n+j], j, i, m.m[j*m.n+i])
 			}
@@ -146,6 +187,7 @@ func (m *matrix) symmetric() error {
 	return nil
 }
 
+// all the balances
 type balances struct {
 	i int
 	*matrix
@@ -161,12 +203,13 @@ func newBalances(n int) *balances {
 	}
 }
 
+// create a new testNode for every node created as part of the service
 func (b *balances) newNode() *testNode {
 	defer func() { b.i++ }()
 	return &testNode{
 		bal:   b,
 		i:     b.i,
-		peers: make([]*testPeer, b.n),
+		peers: make([]*testPeer, b.n), //a node will be connected to n-1 peers
 	}
 }
 
@@ -178,30 +221,39 @@ type testNode struct {
 	peerCount int
 }
 
+// do the accounting for the peer's test protocol
+// testNode implements protocols.Balance
 func (t *testNode) Add(a int64, p *Peer) error {
+	//get the index for the remote peer
 	remote := t.bal.id2n[p.ID()]
-	log.Warn("add", "local", t.i, "remote", remote, "amount", a)
+	log.Debug("add", "local", t.i, "remote", remote, "amount", a)
 	return t.bal.add(t.i, remote, a)
 }
 
+//run the p2p protocol
+//for every node, represented by testNode, create a remote testPeer
 func (t *testNode) run(p *p2p.Peer, rw p2p.MsgReadWriter) error {
 	spec := createTestSpec()
+	//create accounting hook
 	spec.Hook = NewAccounting(t, &dummyPrices{})
 
+	//create a peer for this node
 	tp := &testPeer{NewPeer(p, rw, spec), t.i, t.bal.id2n[p.ID()], t.bal.wg}
 	t.lock.Lock()
 	t.peers[t.bal.id2n[p.ID()]] = tp
 	t.peerCount++
 	if t.peerCount == t.bal.n-1 {
+		//when all peer connections are established, start sending messages from this peer
 		go t.send()
 	}
 	t.lock.Unlock()
 	return tp.Run(tp.handle)
 }
 
+// p2p message receive handler function
 func (tp *testPeer) handle(ctx context.Context, msg interface{}) error {
 	tp.wg.Done()
-	log.Warn("receive", "from", tp.remote, "to", tp.local, "type", reflect.TypeOf(msg), "msg", msg)
+	log.Debug("receive", "from", tp.remote, "to", tp.local, "type", reflect.TypeOf(msg), "msg", msg)
 	return nil
 }
 
@@ -212,8 +264,9 @@ type testPeer struct {
 }
 
 func (t *testNode) send() {
-	log.Warn("start sending")
+	log.Debug("start sending")
 	for i := 0; i < *msgs; i++ {
+		//determine randomly to which peer to send
 		whom := rand.Intn(t.bal.n - 1)
 		if whom >= t.i {
 			whom++
@@ -222,6 +275,7 @@ func (t *testNode) send() {
 		p := t.peers[whom]
 		t.lock.Unlock()
 
+		//determine a random message from the spec's messages to be sent
 		which := rand.Intn(len(p.spec.Messages))
 		msg := p.spec.Messages[which]
 		switch msg.(type) {
@@ -230,11 +284,12 @@ func (t *testNode) send() {
 		case *perBytesMsgSenderPays:
 			msg = &perBytesMsgSenderPays{Content: content[:rand.Intn(len(content))]}
 		}
-		log.Warn("send", "from", t.i, "to", whom, "type", reflect.TypeOf(msg), "msg", msg)
+		log.Debug("send", "from", t.i, "to", whom, "type", reflect.TypeOf(msg), "msg", msg)
 		p.Send(context.TODO(), msg)
 	}
 }
 
+// define the protocol
 func (t *testNode) Protocols() []p2p.Protocol {
 	return []p2p.Protocol{{
 		Length: 100,