feat(Gnovm/std): GasUsed function for std

gnovm/stdlibs/std/gas_used.go

@@ -0,0 +1,26 @@
+package std
+
+/*
+	ref: https://github.com/gnolang/gno/issues/1998
+	this file contains std functions for query gas cost, gas used etc...
+*/
+import (
+	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
+	"github.com/gnolang/gno/tm2/pkg/store"
+)
+
+var (
+	gasUsedInvoked = "GasUsedCalled"
+	/*
+		Consider where to save this config
+		defaultGasConfig = store.DefaultGasConfig()
+	*/
+	// defaultGasConfig = int64(1000)
+	defaultInvokeCost = store.DefaultGasConfig().ReadCostFlat
+)
+
+// DefaultCost will be consumed whenever GasUsed is called, now set it ReadCostPerByte
+func GasUsed(m *gno.Machine) int64 {
+	m.GasMeter.ConsumeGas(defaultInvokeCost, gasUsedInvoked)
+	return m.GasMeter.GasConsumedToLimit()
+}

gnovm/stdlibs/std/gas_used_test.go

@@ -0,0 +1,57 @@
+package std
+
+import (
+	"testing"
+
+	gno "github.com/gnolang/gno/gnovm/pkg/gnolang"
+	"github.com/gnolang/gno/tm2/pkg/store"
+	"github.com/stretchr/testify/assert"
+)
+
+// Focus on test gasToConsume()
+func TestGasUsed(t *testing.T) {
+	t.Parallel()
+	m := gno.NewMachine("gasToConsume", nil)
+	gasCostConfig := store.DefaultGasConfig().ReadCostFlat
+	testTable := []struct {
+		tcName          string
+		gasToConsume    int64
+		gasLimit        int64
+		expectPastLimit bool
+		invokeCost      int64
+	}{
+		{"Test GasUsed Get", 10, 100000, false, gasCostConfig},
+		{"Test GasUsed Invoke Cost", 4, 4 + gasCostConfig, false, gasCostConfig},
+		{"Test GasUsed Past Limit", 4, 4, true, gasCostConfig},
+		// this case is OutOfGas's behavior
+		// {"Test GasUsed Get When Out Of Gas", 40, 4, true, cf.ReadCostPerByte},
+	}
+	for _, tc := range testTable {
+		t.Run(tc.tcName, func(t *testing.T) {
+			m.GasMeter = store.NewGasMeter(tc.gasLimit)
+			if tc.expectPastLimit {
+				m.GasMeter.ConsumeGas(tc.gasToConsume, tc.tcName)
+				// After consume gasToConsume, the remaining gas is lower than invokeCost
+				// then GasUsed() should panic(OutOfGas)
+				beforeInvoke := m.GasMeter.Remaining()
+				assert.Panics(t, func() {
+					GasUsed(m)
+				})
+				afterInvoke := m.GasMeter.Remaining()
+				// Check if GasMeter() acts as expected
+				assert.Equal(t, tc.expectPastLimit, m.GasMeter.IsOutOfGas())
+				// Check if GasUsed() will not consume invokeCost
+				assert.Equal(t, beforeInvoke, afterInvoke)
+			} else {
+				m.GasMeter.ConsumeGas(tc.gasToConsume, tc.tcName)
+				beforeInvoke := m.GasMeter.Remaining()
+				result := GasUsed(m)
+				afterInvoke := m.GasMeter.Remaining()
+				// Check if GasUsed() invoked the invokeCost
+				assert.Equal(t, beforeInvoke-afterInvoke, tc.invokeCost)
+				// Check if the process consumes ecxactly amount of gas
+				assert.Equal(t, tc.gasToConsume+tc.invokeCost, result)
+			}
+		})
+	}
+}

gnovm/stdlibs/std/native.gno

@@ -13,6 +13,8 @@ func IsOriginCall() bool // injected
 func GetChainID() string // injected
 func GetHeight() int64   // injected
 
+func GasUsed() int64           // injected
+
 func GetOrigSend() Coins {
 	den, amt := origSend()
 	coins := make(Coins, len(den))