routing+routerrpc: rename max_shards to max_parts

Don't introduce a new term and align with the P in MPP.

routing/integrated_routing_context_test.go

@@ -88,7 +88,7 @@ func (h htlcAttempt) String() string {
 
 // testPayment launches a test payment and asserts that it is completed after
 // the expected number of attempts.
-func (c *integratedRoutingContext) testPayment(maxShards uint32) ([]htlcAttempt,
+func (c *integratedRoutingContext) testPayment(maxParts uint32) ([]htlcAttempt,
 	error) {
 
 	var (
@@ -137,7 +137,7 @@ func (c *integratedRoutingContext) testPayment(maxShards uint32) ([]htlcAttempt,
 		DestFeatures:   lnwire.NewFeatureVector(mppFeatures, nil),
 		Amount:         c.amt,
 		CltvLimit:      math.MaxUint32,
-		MaxShards:      maxShards,
+		MaxParts:       maxParts,
 	}
 
 	session, err := newPaymentSession(

routing/integrated_routing_test.go

@@ -85,7 +85,7 @@ type mppSendTestCase struct {
 
 	graph           func(g *mockGraph)
 	expectedFailure bool
-	maxShards       uint32
+	maxParts        uint32
 }
 
 const (
@@ -152,7 +152,7 @@ var mppTestCases = []mppSendTestCase{
 				chans: []uint64{chanSourceIm2, chanIm2Target},
 			},
 		},
-		maxShards: 1000,
+		maxParts: 1000,
 	},
 
 	// Test that a cap on the max htlcs makes it impossible to pay.
@@ -165,7 +165,7 @@ var mppTestCases = []mppSendTestCase{
 		expectedAttempts:  2,
 		expectedSuccesses: []expectedHtlcSuccess{},
 		expectedFailure:   true,
-		maxShards:         1,
+		maxParts:          1,
 	},
 
 	// Test that an attempt is made to split the payment in multiple parts
@@ -190,7 +190,7 @@ var mppTestCases = []mppSendTestCase{
 			},
 		},
 		expectedFailure: true,
-		maxShards:       1000,
+		maxParts:        1000,
 	},
 
 	// Test that no attempts are made if the total local balance is
@@ -203,7 +203,7 @@ var mppTestCases = []mppSendTestCase{
 		amt:              300000,
 		expectedAttempts: 0,
 		expectedFailure:  true,
-		maxShards:        10,
+		maxParts:         10,
 	},
 }
 
@@ -226,7 +226,7 @@ func testMppSend(t *testing.T, testCase *mppSendTestCase) {
 
 	ctx.amt = lnwire.NewMSatFromSatoshis(testCase.amt)
 
-	attempts, err := ctx.testPayment(testCase.maxShards)
+	attempts, err := ctx.testPayment(testCase.maxParts)
 	switch {
 	case err == nil && testCase.expectedFailure:
 		t.Fatal("expected payment to fail")

routing/payment_session.go

@@ -263,11 +263,11 @@ func (p *paymentSession) RequestRoute(maxAmt, feeLimit lnwire.MilliSatoshi,
 			}
 
 			// No splitting if this is the last shard.
-			isLastShard := activeShards+1 >= p.payment.MaxShards
+			isLastShard := activeShards+1 >= p.payment.MaxParts
 			if isLastShard {
 				p.log.Debugf("not splitting because shard "+
 					"limit %v has been reached",
-					p.payment.MaxShards)
+					p.payment.MaxParts)
 
 				return nil, errNoPathFound
 			}

routing/router.go

@@ -1625,9 +1625,9 @@ type LightningPayment struct {
 	// fail.
 	DestCustomRecords record.CustomSet
 
-	// MaxShards is the maximum number of partial payments that may be used
+	// MaxParts is the maximum number of partial payments that may be used
 	// to complete the full amount.
-	MaxShards uint32
+	MaxParts uint32
 }
 
 // SendPayment attempts to send a payment as described within the passed