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Conform this function to match SV Node calculation #268

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Merged
shruggr merged 6 commits into from
Nov 12, 2025
Merged

Conform this function to match SV Node calculation #268

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d1a9849
add ArcBroadcast abstraction
shruggr Nov 3, 2025
a342376
add missing ARC status
shruggr Nov 4, 2025
43ca85f
Conform this function to match SV Node calculation
sirdeggen Nov 12, 2025
2ca2c8c
Refactor fee calculation and add unit tests for calculateFee function
shruggr Nov 12, 2025
578fc89
Merge branch 'feat/arc-broadcast' into fix/feemodel
shruggr Nov 12, 2025
d3b8b77
update changelog for v1.2.12
shruggr Nov 12, 2025
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6 changes: 5 additions & 1 deletion transaction/fee_model/sats_per_kb.go
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Original file line number Diff line number Diff line change
Expand Up @@ -33,5 +33,9 @@ func (s *SatoshisPerKilobyte) ComputeFee(tx *transaction.Transaction) (uint64, e
size += len(*o.LockingScript)
}
size += 4
return (uint64(math.Ceil(float64(size)/1000)) * s.Satoshis), nil
return calculateFee(size, s.Satoshis), nil
}

func calculateFee(txSizeBytes int, satoshisPerKB uint64) uint64 {
return uint64(math.Ceil(float64(txSizeBytes) / 1000 * float64(satoshisPerKB)))
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@kuba-4chain kuba-4chain Nov 13, 2025 •
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This changes the fee calculation. Assuming the fee rate is 100sat/KB, if the math.Ceil() is over the entire equation, it allows for the fee to be lower than 100 sats for transactions of size lower than 1 KB. If the math.Ceil() is only over the txSizeBytes / 1000, then the fee will never be lower than 100 sats

}
74 changes: 74 additions & 0 deletions transaction/fee_model/sats_per_kb_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,74 @@
package feemodel

import (
"testing"

"github.com/stretchr/testify/require"
)

func TestCalculateFee(t *testing.T) {
tests := []struct {
name string
txSize int
satoshisPerKB uint64
expectedFee uint64
description string
}{
{
name: "240 bytes at 100 sats/KB",
txSize: 240,
satoshisPerKB: 100,
expectedFee: 24,
description: "240/1000 * 100 = 24 - tests the bug where casting happened before multiplication",
},
{
name: "240 bytes at 1 sat/KB",
txSize: 240,
satoshisPerKB: 1,
expectedFee: 1,
description: "Edge case that would pass even with buggy implementation",
},
{
name: "240 bytes at 10 sats/KB",
txSize: 240,
satoshisPerKB: 10,
expectedFee: 3,
description: "240/1000 * 10 = 2.4, ceil = 3",
},
{
name: "250 bytes at 500 sats/KB",
txSize: 250,
satoshisPerKB: 500,
expectedFee: 125,
description: "250/1000 * 500 = 125",
},
{
name: "1000 bytes at 100 sats/KB",
txSize: 1000,
satoshisPerKB: 100,
expectedFee: 100,
description: "1000/1000 * 100 = 100",
},
{
name: "1500 bytes at 100 sats/KB",
txSize: 1500,
satoshisPerKB: 100,
expectedFee: 150,
description: "1500/1000 * 100 = 150",
},
{
name: "1500 bytes at 500 sats/KB",
txSize: 1500,
satoshisPerKB: 500,
expectedFee: 750,
description: "1500/1000 * 500 = 750",
},
}

for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
fee := calculateFee(tt.txSize, tt.satoshisPerKB)
require.Equal(t, tt.expectedFee, fee, tt.description)
})
}
}
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