Reduce voucher check retry interval (#20)

* Reduce voucher check retry interval to 1s

* Remove unused variables

Author: prathamesh0

paymentsmanager/http_middleware.go

@@ -32,7 +32,7 @@ func HTTPMiddleware(next http.Handler, validator VoucherValidator, queryRates ma
 		// Validate voucher
 		r, err := extractAndValidateVoucher(r, validator, queryRates)
 		if err != nil {
-			if strings.Contains(err.Error(), ErrPayment) {
+			if isPaymentError(err) {
 				http.Error(w, err.Error(), http.StatusPaymentRequired)
 			} else {
 				http.Error(w, err.Error(), http.StatusBadRequest)
@@ -124,3 +124,7 @@ func isRpcCall(r *http.Request) (bool, string) {
 
 	return true, ReqBody.Method
 }
+
+func isPaymentError(err error) bool {
+	return strings.HasPrefix(err.Error(), ERR_PAYMENT)
+}

paymentsmanager/payments_manager.go

@@ -1,6 +1,7 @@
 package paymentsmanager
 
 import (
+	"fmt"
 	"log/slog"
 	"math/big"
 	"sync"
@@ -22,13 +23,15 @@ const (
 	DEFAULT_LRU_CACHE_MAX_PAYMENT_CHANNELS     = 10000
 	DEFAULT_LRU_CACHE_PAYMENT_CHANNEL_TTL      = DEFAULT_LRU_CACHE_ACCOUNT_TTL
 
-	DEFAULT_VOUCHER_CHECK_INTERVAL = 2
+	// Note: Make sure the transport has timeout > DEFAULT_VOUCHER_CHECK_ATTEMPTS * DEFAULT_VOUCHER_CHECK_INTERVAL
+	DEFAULT_VOUCHER_CHECK_INTERVAL = 1
 	DEFAULT_VOUCHER_CHECK_ATTEMPTS = 5
 )
 
 var (
-	ERR_PAYMENT_NOT_RECEIVED        = "ERR_PAYMENT_NOT_RECEIVED"
-	ERR_PAYMENT_AMOUNT_INSUFFICIENT = "ERR_PAYMENT_AMOUNT_INSUFFICIENT"
+	ERR_PAYMENT                     = "ERR_PAYMENT"
+	ERR_PAYMENT_NOT_RECEIVED        = fmt.Sprintf("%s_NOT_RECEIVED", ERR_PAYMENT)
+	ERR_PAYMENT_AMOUNT_INSUFFICIENT = fmt.Sprintf("%s_AMOUNT_INSUFFICIENT", ERR_PAYMENT)
 )
 
 type InFlightVoucher struct {

paymentsmanager/validator.go

@@ -7,12 +7,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
-var (
-	ErrPayment            = "Payment error:"
-	ErrPaymentNotReceived = fmt.Errorf("%s payment not received", ErrPayment)
-	ErrAmountInsufficient = fmt.Errorf("%s amount insufficient", ErrPayment)
-)
-
 // Voucher validator interface to be satisfied by implementations
 // using in / out of process Nitro nodes
 type VoucherValidator interface {