Moved execution from vm to chain.

This moves call and create to the specified environments. Vms are no
longer re-used. Vm uses environment's Call(Code) and Create in order to
execute new contracts or transfer value between accounts.

State transition now uses the same mechanism described above.

1 files changed, 80 insertions, 0 deletions

diff --git a/chain/execution.go b/chain/execution.go
new file mode 100644
index 000000000..932ffa868
--- /dev/null
+++ b/chain/execution.go
@@ -0,0 +1,80 @@
+package chain
+
+import (
+	"fmt"
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/ethutil"
+	"github.com/ethereum/go-ethereum/state"
+	"github.com/ethereum/go-ethereum/vm"
+)
+
+type Execution struct {
+	vm                vm.VirtualMachine
+	address, input    []byte
+	Gas, price, value *big.Int
+	object            *state.StateObject
+	SkipTransfer      bool
+}
+
+func NewExecution(vm vm.VirtualMachine, address, input []byte, gas, gasPrice, value *big.Int) *Execution {
+	return &Execution{vm: vm, address: address, input: input, Gas: gas, price: gasPrice, value: value}
+}
+
+func (self *Execution) Addr() []byte {
+	return self.address
+}
+
+func (self *Execution) Call(codeAddr []byte, caller vm.ClosureRef) ([]byte, error) {
+	// Retrieve the executing code
+	code := self.vm.Env().State().GetCode(codeAddr)
+
+	return self.exec(code, codeAddr, caller)
+}
+
+func (self *Execution) exec(code, caddr []byte, caller vm.ClosureRef) (ret []byte, err error) {
+	env := self.vm.Env()
+
+	chainlogger.Debugf("pre state %x\n", env.State().Root())
+	snapshot := env.State().Copy()
+	defer func() {
+		if vm.IsDepthErr(err) || vm.IsOOGErr(err) {
+			env.State().Set(snapshot)
+		}
+		chainlogger.Debugf("post state %x\n", env.State().Root())
+	}()
+
+	from, to := env.State().GetStateObject(caller.Address()), env.State().GetOrNewStateObject(self.address)
+	// Skipping transfer is used on testing for the initial call
+	if !self.SkipTransfer {
+		err = env.Transfer(from, to, self.value)
+	}
+
+	if err != nil {
+		caller.ReturnGas(self.Gas, self.price)
+
+		err = fmt.Errorf("Insufficient funds to transfer value. Req %v, has %v", self.value, from.Balance)
+	} else {
+		self.object = to
+		// Pre-compiled contracts (address.go) 1, 2 & 3.
+		naddr := ethutil.BigD(caddr).Uint64()
+		if p := vm.Precompiled[naddr]; p != nil {
+			if self.Gas.Cmp(p.Gas) >= 0 {
+				ret = p.Call(self.input)
+				self.vm.Printf("NATIVE_FUNC(%x) => %x", naddr, ret)
+				self.vm.Endl()
+			}
+		} else {
+			ret, err = self.vm.Run(to, caller, code, self.value, self.Gas, self.price, self.input)
+		}
+	}
+
+	return
+}
+
+func (self *Execution) Create(caller vm.ClosureRef) (ret []byte, err error, account *state.StateObject) {
+	ret, err = self.exec(self.input, nil, caller)
+	account = self.vm.Env().State().GetStateObject(self.address)
+
+	return
+}