Patch txpool core/list for managing multi currencies (#43) (#55)

Modifies the legacypool, list, and priceheap to allow for multi currency txs.

common/celo_types.go

@@ -1,5 +1,34 @@
 package common
 
+import (
+	"math/big"
+)
+
 var (
 	ZeroAddress = BytesToAddress([]byte{})
 )
+
+type ExchangeRates = map[Address]*big.Rat
+
+func IsCurrencyWhitelisted(exchangeRates ExchangeRates, feeCurrency *Address) bool {
+	if feeCurrency == nil {
+		return true
+	}
+
+	// Check if fee currency is registered
+	_, ok := exchangeRates[*feeCurrency]
+	return ok
+}
+
+func AreSameAddress(a, b *Address) bool {
+	// both are nil or point to the same address
+	if a == b {
+		return true
+	}
+	// if only one is nil
+	if a == nil || b == nil {
+		return false
+	}
+	// if they point to the same
+	return *a == *b
+}

common/celo_types_test.go

@@ -0,0 +1,47 @@
+package common
+
+import (
+	"math/big"
+	"testing"
+)
+
+var (
+	currA         = HexToAddress("0xA")
+	currB         = HexToAddress("0xB")
+	currX         = HexToAddress("0xF")
+	exchangeRates = ExchangeRates{
+		currA: big.NewRat(47, 100),
+		currB: big.NewRat(45, 100),
+	}
+)
+
+func TestIsWhitelisted(t *testing.T) {
+	tests := []struct {
+		name        string
+		feeCurrency *Address
+		want        bool
+	}{
+		{
+			name:        "no fee currency",
+			feeCurrency: nil,
+			want:        true,
+		},
+		{
+			name:        "valid fee currency",
+			feeCurrency: &currA,
+			want:        true,
+		},
+		{
+			name:        "invalid fee currency",
+			feeCurrency: &currX,
+			want:        false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := IsCurrencyWhitelisted(exchangeRates, tt.feeCurrency); got != tt.want {
+				t.Errorf("IsWhitelisted() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

common/exchange/rates.go

@@ -0,0 +1,102 @@
+package exchange
+
+import (
+	"errors"
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/log"
+)
+
+var (
+	unitRate = big.NewRat(1, 1)
+	// ErrNonWhitelistedFeeCurrency is returned if the currency specified to use for the fees
+	// isn't one of the currencies whitelisted for that purpose.
+	ErrNonWhitelistedFeeCurrency = errors.New("non-whitelisted fee currency address")
+)
+
+// ConvertCurrency does an exchange conversion from currencyFrom to currencyTo of the value given.
+func ConvertCurrency(exchangeRates common.ExchangeRates, val1 *big.Int, currencyFrom *common.Address, currencyTo *common.Address) *big.Int {
+	goldAmount, err := ConvertCurrencyToGold(exchangeRates, val1, currencyFrom)
+	if err != nil {
+		log.Error("Error trying to convert from currency to gold.", "value", val1, "fromCurrency", currencyFrom.Hex())
+	}
+	toAmount, err := ConvertGoldToCurrency(exchangeRates, currencyTo, goldAmount)
+	if err != nil {
+		log.Error("Error trying to convert from gold to currency.", "value", goldAmount, "toCurrency", currencyTo.Hex())
+	}
+	return toAmount
+}
+
+func ConvertCurrencyToGold(exchangeRates common.ExchangeRates, currencyAmount *big.Int, feeCurrency *common.Address) (*big.Int, error) {
+	if feeCurrency == nil {
+		return currencyAmount, nil
+	}
+	exchangeRate, ok := exchangeRates[*feeCurrency]
+	if !ok {
+		return nil, ErrNonWhitelistedFeeCurrency
+	}
+	return new(big.Int).Div(new(big.Int).Mul(currencyAmount, exchangeRate.Denom()), exchangeRate.Num()), nil
+}
+
+func ConvertGoldToCurrency(exchangeRates common.ExchangeRates, feeCurrency *common.Address, goldAmount *big.Int) (*big.Int, error) {
+	if feeCurrency == nil {
+		return goldAmount, nil
+	}
+	exchangeRate, ok := exchangeRates[*feeCurrency]
+	if !ok {
+		return nil, ErrNonWhitelistedFeeCurrency
+	}
+	return new(big.Int).Div(new(big.Int).Mul(goldAmount, exchangeRate.Num()), exchangeRate.Denom()), nil
+}
+
+func getRate(exchangeRates common.ExchangeRates, feeCurrency *common.Address) (*big.Rat, error) {
+	if feeCurrency == nil {
+		return unitRate, nil
+	}
+	rate, ok := exchangeRates[*feeCurrency]
+	if !ok {
+		return nil, fmt.Errorf("fee currency not registered: %s", feeCurrency.Hex())
+	}
+	return rate, nil
+}
+
+// CompareValue compares values in different currencies (nil currency is native currency)
+// returns -1 0 or 1 depending if val1 < val2, val1 == val2, or val1 > val2 respectively.
+func CompareValue(exchangeRates common.ExchangeRates, val1 *big.Int, feeCurrency1 *common.Address, val2 *big.Int, feeCurrency2 *common.Address) (int, error) {
+	// Short circuit if the fee currency is the same.
+	if feeCurrency1 == feeCurrency2 {
+		return val1.Cmp(val2), nil
+	}
+
+	exchangeRate1, err := getRate(exchangeRates, feeCurrency1)
+	if err != nil {
+		return 0, err
+	}
+	exchangeRate2, err := getRate(exchangeRates, feeCurrency2)
+	if err != nil {
+		return 0, err
+	}
+
+	// Below code block is basically evaluating this comparison:
+	// val1 * exchangeRate1.denominator / exchangeRate1.numerator < val2 * exchangeRate2.denominator / exchangeRate2.numerator
+	// It will transform that comparison to this, to remove having to deal with fractional values.
+	// val1 * exchangeRate1.denominator * exchangeRate2.numerator < val2 * exchangeRate2.denominator * exchangeRate1.numerator
+	leftSide := new(big.Int).Mul(
+		val1,
+		new(big.Int).Mul(
+			exchangeRate1.Denom(),
+			exchangeRate2.Num(),
+		),
+	)
+	rightSide := new(big.Int).Mul(
+		val2,
+		new(big.Int).Mul(
+			exchangeRate2.Denom(),
+			exchangeRate1.Num(),
+		),
+	)
+
+	return leftSide.Cmp(rightSide), nil
+}

common/exchange/rates_test.go

@@ -0,0 +1,171 @@
+package exchange
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+var (
+	currA         = common.HexToAddress("0xA")
+	currB         = common.HexToAddress("0xB")
+	currX         = common.HexToAddress("0xF")
+	exchangeRates = common.ExchangeRates{
+		currA: big.NewRat(47, 100),
+		currB: big.NewRat(45, 100),
+	}
+)
+
+func TestCompareFees(t *testing.T) {
+	type args struct {
+		val1         *big.Int
+		feeCurrency1 *common.Address
+		val2         *big.Int
+		feeCurrency2 *common.Address
+	}
+	tests := []struct {
+		name       string
+		args       args
+		wantResult int
+		wantErr    bool
+	}{
+		// Native currency
+		{
+			name: "Same amount of native currency",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: nil,
+				val2:         big.NewInt(1),
+				feeCurrency2: nil,
+			},
+			wantResult: 0,
+		}, {
+			name: "Different amounts of native currency 1",
+			args: args{
+				val1:         big.NewInt(2),
+				feeCurrency1: nil,
+				val2:         big.NewInt(1),
+				feeCurrency2: nil,
+			},
+			wantResult: 1,
+		}, {
+			name: "Different amounts of native currency 2",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: nil,
+				val2:         big.NewInt(5),
+				feeCurrency2: nil,
+			},
+			wantResult: -1,
+		},
+		// Mixed currency
+		{
+			name: "Same amount of mixed currency",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: nil,
+				val2:         big.NewInt(1),
+				feeCurrency2: &currA,
+			},
+			wantResult: -1,
+		}, {
+			name: "Different amounts of mixed currency 1",
+			args: args{
+				val1:         big.NewInt(100),
+				feeCurrency1: nil,
+				val2:         big.NewInt(47),
+				feeCurrency2: &currA,
+			},
+			wantResult: 0,
+		}, {
+			name: "Different amounts of mixed currency 2",
+			args: args{
+				val1:         big.NewInt(45),
+				feeCurrency1: &currB,
+				val2:         big.NewInt(100),
+				feeCurrency2: nil,
+			},
+			wantResult: 0,
+		},
+		// Two fee currencies
+		{
+			name: "Same amount of same currency",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(1),
+				feeCurrency2: &currA,
+			},
+			wantResult: 0,
+		}, {
+			name: "Different amounts of same currency 1",
+			args: args{
+				val1:         big.NewInt(3),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(1),
+				feeCurrency2: &currA,
+			},
+			wantResult: 1,
+		}, {
+			name: "Different amounts of same currency 2",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(7),
+				feeCurrency2: &currA,
+			},
+			wantResult: -1,
+		}, {
+			name: "Different amounts of different currencies 1",
+			args: args{
+				val1:         big.NewInt(47),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(45),
+				feeCurrency2: &currB,
+			},
+			wantResult: 0,
+		}, {
+			name: "Different amounts of different currencies 2",
+			args: args{
+				val1:         big.NewInt(48),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(45),
+				feeCurrency2: &currB,
+			},
+			wantResult: 1,
+		}, {
+			name: "Different amounts of different currencies 3",
+			args: args{
+				val1:         big.NewInt(47),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(46),
+				feeCurrency2: &currB,
+			},
+			wantResult: -1,
+		},
+		// Unregistered fee currency
+		{
+			name: "Different amounts of different currencies",
+			args: args{
+				val1:         big.NewInt(1),
+				feeCurrency1: &currA,
+				val2:         big.NewInt(1),
+				feeCurrency2: &currX,
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := CompareValue(exchangeRates, tt.args.val1, tt.args.feeCurrency1, tt.args.val2, tt.args.feeCurrency2)
+
+			if tt.wantErr && err == nil {
+				t.Error("Expected error in CompareValue()")
+			}
+			if got != tt.wantResult {
+				t.Errorf("CompareValue() = %v, want %v", got, tt.wantResult)
+			}
+		})
+	}
+}