types: make timely predicate adaptive per round

types/proposal.go

@@ -3,6 +3,7 @@ package types
 import (
 	"errors"
 	"fmt"
+	"math"
 	"time"
 
 	"github.com/tendermint/tendermint/internal/libs/protoio"
@@ -89,11 +90,19 @@ func (p *Proposal) ValidateBasic() error {
 //
 // For more information on the meaning of 'timely', see the proposer-based timestamp specification:
 // https://github.com/tendermint/spec/tree/master/spec/consensus/proposer-based-timestamp
-func (p *Proposal) IsTimely(recvTime time.Time, sp SynchronyParams) bool {
+func (p *Proposal) IsTimely(recvTime time.Time, sp SynchronyParams, round int32) bool {
+	// The message delay values are scaled as rounds progress.
+	// Every 10 rounds, the message delay is doubled to allow consensus to
+	// proceed in the case that the choosen value was too small for the given network conditions.
+	// For more information and discussion on this mechanism, see the relevant github issue:
+	// https://github.com/tendermint/spec/issues/371
+	roundModifier := time.Duration(math.Exp2(float64(round / 10)))
+	msgDelay := sp.MessageDelay * roundModifier
+
 	// lhs is `proposedBlockTime - Precision` in the first inequality
 	lhs := p.Timestamp.Add(-sp.Precision)
 	// rhs is `proposedBlockTime + MsgDelay + Precision` in the second inequality
-	rhs := p.Timestamp.Add(sp.MessageDelay).Add(sp.Precision)
+	rhs := p.Timestamp.Add(msgDelay).Add(sp.Precision)
 
 	if recvTime.Before(lhs) || recvTime.After(rhs) {
 		return false

types/proposal_test.go

@@ -216,54 +216,61 @@ func TestIsTimely(t *testing.T) {
 	genesisTime, err := time.Parse(time.RFC3339, "2019-03-13T23:00:00Z")
 	require.NoError(t, err)
 	testCases := []struct {
-		name           string
-		proposalHeight int64
-		proposalTime   time.Time
-		recvTime       time.Time
-		precision      time.Duration
-		msgDelay       time.Duration
-		expectTimely   bool
+		name         string
+		proposalTime time.Time
+		recvTime     time.Time
+		precision    time.Duration
+		msgDelay     time.Duration
+		expectTimely bool
+		round        int32
 	}{
 		// proposalTime - precision <= localTime <= proposalTime + msgDelay + precision
 		{
 			// Checking that the following inequality evaluates to true:
 			// 0 - 2 <= 1 <= 0 + 1 + 2
-			name:           "basic timely",
-			proposalHeight: 2,
-			proposalTime:   genesisTime,
-			recvTime:       genesisTime.Add(1 * time.Nanosecond),
-			precision:      time.Nanosecond * 2,
-			msgDelay:       time.Nanosecond,
-			expectTimely:   true,
+			name:         "basic timely",
+			proposalTime: genesisTime,
+			recvTime:     genesisTime.Add(1 * time.Nanosecond),
+			precision:    time.Nanosecond * 2,
+			msgDelay:     time.Nanosecond,
+			expectTimely: true,
 		},
 		{
 			// Checking that the following inequality evaluates to false:
 			// 0 - 2 <= 4 <= 0 + 1 + 2
-			name:           "local time too large",
-			proposalHeight: 2,
-			proposalTime:   genesisTime,
-			recvTime:       genesisTime.Add(4 * time.Nanosecond),
-			precision:      time.Nanosecond * 2,
-			msgDelay:       time.Nanosecond,
-			expectTimely:   false,
+			name:         "local time too large",
+			proposalTime: genesisTime,
+			recvTime:     genesisTime.Add(4 * time.Nanosecond),
+			precision:    time.Nanosecond * 2,
+			msgDelay:     time.Nanosecond,
+			expectTimely: false,
 		},
 		{
 			// Checking that the following inequality evaluates to false:
 			// 4 - 2 <= 0 <= 4 + 2 + 1
-			name:           "proposal time too large",
-			proposalHeight: 2,
-			proposalTime:   genesisTime.Add(4 * time.Nanosecond),
-			recvTime:       genesisTime,
-			precision:      time.Nanosecond * 2,
-			msgDelay:       time.Nanosecond,
-			expectTimely:   false,
+			name:         "proposal time too large",
+			proposalTime: genesisTime.Add(4 * time.Nanosecond),
+			recvTime:     genesisTime,
+			precision:    time.Nanosecond * 2,
+			msgDelay:     time.Nanosecond,
+			expectTimely: false,
+		},
+		{
+			// Checking that the following inequality evaluates to true:
+			// 0 - (2 * 2)  <= 4 <= 0 + (1 * 2) + 2
+			name:         "message delay adapts after 10 rounds",
+			proposalTime: genesisTime,
+			recvTime:     genesisTime.Add(4 * time.Nanosecond),
+			precision:    time.Nanosecond * 2,
+			msgDelay:     time.Nanosecond,
+			expectTimely: true,
+			round:        10,
 		},
 	}
 
 	for _, testCase := range testCases {
 		t.Run(testCase.name, func(t *testing.T) {
 			p := Proposal{
-				Height:    testCase.proposalHeight,
 				Timestamp: testCase.proposalTime,
 			}
 
@@ -272,7 +279,7 @@ func TestIsTimely(t *testing.T) {
 				MessageDelay: testCase.msgDelay,
 			}
 
-			ti := p.IsTimely(testCase.recvTime, sp)
+			ti := p.IsTimely(testCase.recvTime, sp, testCase.round)
 			assert.Equal(t, testCase.expectTimely, ti)
 		})
 	}