core: set free GAS limit via config

config/config.go

@@ -54,6 +54,8 @@ type (
 		VerifyBlocks bool `yaml:"VerifyBlocks"`
 		// Whether to verify transactions in received blocks.
 		VerifyTransactions bool `yaml:"VerifyTransactions"`
+		// FreeGasLimit is an amount of GAS which can be spent for free.
+		FreeGasLimit util.Fixed8 `yaml:"FreeGasLimit"`
 	}
 
 	// SystemFee fees related to system.

config/protocol.mainnet.yml

@@ -29,6 +29,7 @@ ProtocolConfiguration:
     RegisterTransaction: 10000
   VerifyBlocks: true
   VerifyTransactions: false
+  FreeGasLimit: 10.0
 
 ApplicationConfiguration:
   # LogPath could be set up in case you need stdout logs to some proper file.

config/protocol.testnet.yml

@@ -29,6 +29,7 @@ ProtocolConfiguration:
     RegisterTransaction: 100
   VerifyBlocks: true
   VerifyTransactions: false
+  FreeGasLimit: 10.0
 
 ApplicationConfiguration:
   # LogPath could be set up in case you need stdout logs to some proper file.

pkg/core/blockchain.go

@@ -515,9 +515,9 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 			v.SetCheckedHash(tx.VerificationHash().BytesBE())
 			v.LoadScript(t.Script)
 			v.SetPriceGetter(getPrice)
-
-			gasAmount := util.Fixed8FromInt64(10) + t.Gas
-			v.SetGasLimit(gasAmount)
+			if bc.config.FreeGasLimit >= 0 {
+				v.SetGasLimit(bc.config.FreeGasLimit + t.Gas)
+			}
 
 			err := v.Run()
 			if !v.HasFailed() {