Make gas costs of counter increments uniform (#291)

Author: HerbertJordan

load/app/counter_app.go

@@ -128,7 +128,7 @@ func (g *CounterUser) GenerateTx(currentGasPrice *big.Int) (*types.Transaction,
 	}
 
 	// prepare tx
-	const gasLimit = 50000 // IncrementCounter method call takes 43426 of gas
+	const gasLimit = 28036
 	tx, err := createTx(g.sender, g.contract, big.NewInt(0), data, currentGasPrice, gasLimit)
 	if err == nil {
 		g.sentTxs.Add(1)

load/contracts/Counter.sol

@@ -2,17 +2,17 @@
 pragma solidity ^0.8.4;
 
 contract Counter {
-    int private count = 0;
+    // counter is an internal counter tracking the number of increment calls.
+    // The counter is initialized to 1 to make all increment-counter calls
+    // equally expensive. Otherwise, the first call incrementing the counter
+    // from 0 to 1 would have to pay extra gas for the storage allocation.
+    int private count = 1;
 
     function incrementCounter() public {
         count += 1;
     }
 
-    function decrementCounter() public {
-        count -= 1;
-    }
-
     function getCount() public view returns (int) {
-        return count;
+        return count-1;
     }
 }

load/contracts/abi/Counter.abi

@@ -1,16 +1,8 @@
 [
-  {
-    "inputs": [],
-    "name": "decrementCounter",
-    "outputs": [],
-    "stateMutability": "nonpayable",
-    "type": "function"
-  },
   {
     "inputs": [],
     "name": "getCount",
-    "outputs":
-    [
+    "outputs": [
       {
         "internalType": "int256",
         "name": "",

load/contracts/abi/Counter.bin

@@ -1 +1 @@
-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