core: Added EVM configuration options

The EVM is now initialised with an additional configured object that
allows you to turn on debugging options.

20 files changed, 385 insertions, 194 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index 534318ecd..cecb914a8 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -891,7 +891,7 @@ func (self *BlockChain) InsertChain(chain types.Blocks) (int, error) {
 			return i, err
 		}
 		// Process block using the parent state as reference point.
-		receipts, logs, usedGas, err := self.processor.Process(block, statedb)
+		receipts, logs, usedGas, err := self.processor.Process(block, statedb, nil)
 		if err != nil {
 			reportBlock(block, err)
 			return i, err
diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index df979578e..d7cd24fa8 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -141,7 +141,7 @@ func testBlockChainImport(chain types.Blocks, blockchain *BlockChain) error {
 		if err != nil {
 			return err
 		}
-		receipts, _, usedGas, err := blockchain.Processor().Process(block, statedb)
+		receipts, _, usedGas, err := blockchain.Processor().Process(block, statedb, nil)
 		if err != nil {
 			reportBlock(block, err)
 			return err
@@ -435,7 +435,7 @@ func (bproc) ValidateHeader(*types.Header, *types.Header, bool) error { return n
 func (bproc) ValidateState(block, parent *types.Block, state *state.StateDB, receipts types.Receipts, usedGas *big.Int) error {
 	return nil
 }
-func (bproc) Process(block *types.Block, statedb *state.StateDB) (types.Receipts, vm.Logs, *big.Int, error) {
+func (bproc) Process(block *types.Block, statedb *state.StateDB, cfg *vm.Config) (types.Receipts, vm.Logs, *big.Int, error) {
 	return nil, nil, nil, nil
 }
 
diff --git a/core/chain_makers.go b/core/chain_makers.go
index 0e1ca5fff..7ae3c98b0 100644
--- a/core/chain_makers.go
+++ b/core/chain_makers.go
@@ -91,7 +91,7 @@ func (b *BlockGen) AddTx(tx *types.Transaction) {
 		b.SetCoinbase(common.Address{})
 	}
 	b.statedb.StartRecord(tx.Hash(), common.Hash{}, len(b.txs))
-	receipt, _, _, err := ApplyTransaction(nil, b.gasPool, b.statedb, b.header, tx, b.header.GasUsed)
+	receipt, _, _, err := ApplyTransaction(nil, b.gasPool, b.statedb, b.header, tx, b.header.GasUsed, nil)
 	if err != nil {
 		panic(err)
 	}
diff --git a/core/state/state_object.go b/core/state/state_object.go
index 0f86325c6..326708118 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -38,7 +38,7 @@ func (self Code) String() string {
 	return string(self) //strings.Join(Disassemble(self), " ")
 }
 
-type Storage map[string]common.Hash
+type Storage map[common.Hash]common.Hash
 
 func (self Storage) String() (str string) {
 	for key, value := range self {
@@ -112,13 +112,13 @@ func (c *StateObject) getAddr(addr common.Hash) common.Hash {
 	return common.BytesToHash(ret)
 }
 
-func (c *StateObject) setAddr(addr []byte, value common.Hash) {
+func (c *StateObject) setAddr(addr, value common.Hash) {
 	v, err := rlp.EncodeToBytes(bytes.TrimLeft(value[:], "\x00"))
 	if err != nil {
 		// if RLPing failed we better panic and not fail silently. This would be considered a consensus issue
 		panic(err)
 	}
-	c.trie.Update(addr, v)
+	c.trie.Update(addr[:], v)
 }
 
 func (self *StateObject) Storage() Storage {
@@ -126,20 +126,19 @@ func (self *StateObject) Storage() Storage {
 }
 
 func (self *StateObject) GetState(key common.Hash) common.Hash {
-	strkey := key.Str()
-	value, exists := self.storage[strkey]
+	value, exists := self.storage[key]
 	if !exists {
 		value = self.getAddr(key)
 		if (value != common.Hash{}) {
-			self.storage[strkey] = value
+			self.storage[key] = value
 		}
 	}
 
 	return value
 }
 
-func (self *StateObject) SetState(k, value common.Hash) {
-	self.storage[k.Str()] = value
+func (self *StateObject) SetState(key, value common.Hash) {
+	self.storage[key] = value
 	self.dirty = true
 }
 
@@ -147,10 +146,10 @@ func (self *StateObject) SetState(k, value common.Hash) {
 func (self *StateObject) Update() {
 	for key, value := range self.storage {
 		if (value == common.Hash{}) {
-			self.trie.Delete([]byte(key))
+			self.trie.Delete(key[:])
 			continue
 		}
-		self.setAddr([]byte(key), value)
+		self.setAddr(key, value)
 	}
 }
 
@@ -245,24 +244,22 @@ func (self *StateObject) Value() *big.Int {
 	panic("Value on StateObject should never be called")
 }
 
-func (self *StateObject) EachStorage(cb func(key, value []byte)) {
+func (self *StateObject) ForEachStorage(cb func(key, value common.Hash) bool) {
 	// When iterating over the storage check the cache first
-	for h, v := range self.storage {
-		cb([]byte(h), v.Bytes())
+	for h, value := range self.storage {
+		cb(h, value)
 	}
 
 	it := self.trie.Iterator()
 	for it.Next() {
 		// ignore cached values
-		key := self.trie.GetKey(it.Key)
-		if _, ok := self.storage[string(key)]; !ok {
-			cb(key, it.Value)
+		key := common.BytesToHash(self.trie.GetKey(it.Key))
+		if _, ok := self.storage[key]; !ok {
+			cb(key, common.BytesToHash(it.Value))
 		}
 	}
 }
 
-// Encoding
-
 type extStateObject struct {
 	Nonce    uint64
 	Balance  *big.Int
diff --git a/core/state_processor.go b/core/state_processor.go
index 3ca36a43a..38cd0e675 100644
--- a/core/state_processor.go
+++ b/core/state_processor.go
@@ -31,7 +31,7 @@ func NewStateProcessor(bc *BlockChain) *StateProcessor {
 // Process returns the receipts and logs accumulated during the process and
 // returns the amount of gas that was used in the process. If any of the
 // transactions failed to execute due to insufficient gas it will return an error.
-func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB) (types.Receipts, vm.Logs, *big.Int, error) {
+func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg *vm.Config) (types.Receipts, vm.Logs, *big.Int, error) {
 	var (
 		receipts     types.Receipts
 		totalUsedGas = big.NewInt(0)
@@ -43,7 +43,7 @@ func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB) (ty
 
 	for i, tx := range block.Transactions() {
 		statedb.StartRecord(tx.Hash(), block.Hash(), i)
-		receipt, logs, _, err := ApplyTransaction(p.bc, gp, statedb, header, tx, totalUsedGas)
+		receipt, logs, _, err := ApplyTransaction(p.bc, gp, statedb, header, tx, totalUsedGas, cfg)
 		if err != nil {
 			return nil, nil, totalUsedGas, err
 		}
@@ -60,8 +60,8 @@ func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB) (ty
 //
 // ApplyTransactions returns the generated receipts and vm logs during the
 // execution of the state transition phase.
-func ApplyTransaction(bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int) (*types.Receipt, vm.Logs, *big.Int, error) {
-	_, gas, err := ApplyMessage(NewEnv(statedb, bc, tx, header), tx, gp)
+func ApplyTransaction(bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, cfg *vm.Config) (*types.Receipt, vm.Logs, *big.Int, error) {
+	_, gas, err := ApplyMessage(NewEnv(statedb, bc, tx, header, cfg), tx, gp)
 	if err != nil {
 		return nil, nil, nil, err
 	}
diff --git a/core/state_transition.go b/core/state_transition.go
index 2887f6228..cc357aaca 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -137,6 +137,7 @@ func (self *StateTransition) from() (vm.Account, error) {
 	}
 	return self.state.GetAccount(f), nil
 }
+
 func (self *StateTransition) to() vm.Account {
 	if self.msg == nil {
 		return nil
@@ -193,7 +194,6 @@ func (self *StateTransition) preCheck() (err error) {
 	}
 
 	// Make sure this transaction's nonce is correct
-	//if sender.Nonce() != msg.Nonce() {
 	if n := self.state.GetNonce(sender.Address()); n != msg.Nonce() {
 		return NonceError(msg.Nonce(), n)
 	}
@@ -253,10 +253,6 @@ func (self *StateTransition) transitionDb() (ret []byte, usedGas *big.Int, err e
 		err = nil
 	}
 
-	if vm.Debug {
-		vm.StdErrFormat(vmenv.StructLogs())
-	}
-
 	self.refundGas()
 	self.state.AddBalance(self.env.Coinbase(), new(big.Int).Mul(self.gasUsed(), self.gasPrice))
 
diff --git a/core/types.go b/core/types.go
index 022528374..af9bc567b 100644
--- a/core/types.go
+++ b/core/types.go
@@ -61,7 +61,7 @@ type HeaderValidator interface {
 // of gas used in the process and return an error if any of the internal rules
 // failed.
 type Processor interface {
-	Process(block *types.Block, statedb *state.StateDB) (types.Receipts, vm.Logs, *big.Int, error)
+	Process(block *types.Block, statedb *state.StateDB, cfg *vm.Config) (types.Receipts, vm.Logs, *big.Int, error)
 }
 
 // Backend is an interface defining the basic functionality for an operable node
diff --git a/core/vm/common.go b/core/vm/common.go
index f73bc1527..2878b92d2 100644
--- a/core/vm/common.go
+++ b/core/vm/common.go
@@ -24,11 +24,6 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-// Global Debug flag indicating Debug VM (full logging)
-var Debug bool
-
-var GenerateStructLogs bool = false
-
 // Type is the VM type accepted by **NewVm**
 type Type byte
 
diff --git a/core/vm/contract.go b/core/vm/contract.go
index d23995218..59e8f1aa6 100644
--- a/core/vm/contract.go
+++ b/core/vm/contract.go
@@ -28,7 +28,7 @@ type ContractRef interface {
 	Address() common.Address
 	Value() *big.Int
 	SetCode([]byte)
-	EachStorage(cb func(key, value []byte))
+	ForEachStorage(callback func(key, value common.Hash) bool)
 }
 
 // Contract represents an ethereum contract in the state database. It contains
@@ -156,6 +156,6 @@ func (self *Contract) SetCallCode(addr *common.Address, code []byte) {
 
 // EachStorage iterates the contract's storage and calls a method for every key
 // value pair.
-func (self *Contract) EachStorage(cb func(key, value []byte)) {
-	self.caller.EachStorage(cb)
+func (self *Contract) ForEachStorage(cb func(key, value common.Hash) bool) {
+	self.caller.ForEachStorage(cb)
 }
diff --git a/core/vm/environment.go b/core/vm/environment.go
index 3c530962b..568218edd 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -22,9 +22,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
-// Environment is is required by the virtual machine to get information from
-// it's own isolated environment.
-
 // Environment is an EVM requirement and helper which allows access to outside
 // information such as states.
 type Environment interface {
@@ -54,12 +51,8 @@ type Environment interface {
 	Transfer(from, to Account, amount *big.Int)
 	// Adds a LOG to the state
 	AddLog(*Log)
-	// Adds a structured log to the env
-	AddStructLog(StructLog)
-	// Returns all coalesced structured logs
-	StructLogs() []StructLog
 	// Type of the VM
-	Vm() *Vm
+	Vm() Vm
 	// Current calling depth
 	Depth() int
 	SetDepth(i int)
@@ -74,7 +67,15 @@ type Environment interface {
 	Create(me ContractRef, data []byte, gas, price, value *big.Int) ([]byte, common.Address, error)
 }
 
-// Database is a EVM database for full state querying
+// Vm is the basic interface for an implementation of the EVM.
+type Vm interface {
+	// Run should execute the given contract with the input given in in
+	// and return the contract execution return bytes or an error if it
+	// failed.
+	Run(c *Contract, in []byte) ([]byte, error)
+}
+
+// Database is a EVM database for full state querying.
 type Database interface {
 	GetAccount(common.Address) Account
 	CreateAccount(common.Address) Account
@@ -99,19 +100,7 @@ type Database interface {
 	IsDeleted(common.Address) bool
 }
 
-// StructLog is emitted to the Environment each cycle and lists information about the current internal state
-// prior to the execution of the statement.
-type StructLog struct {
-	Pc      uint64
-	Op      OpCode
-	Gas     *big.Int
-	GasCost *big.Int
-	Memory  []byte
-	Stack   []*big.Int
-	Storage map[common.Hash][]byte
-	Err     error
-}
-
+// Account represents a contract or basic ethereum account.
 type Account interface {
 	SubBalance(amount *big.Int)
 	AddBalance(amount *big.Int)
@@ -121,6 +110,6 @@ type Account interface {
 	Address() common.Address
 	ReturnGas(*big.Int, *big.Int)
 	SetCode([]byte)
-	EachStorage(cb func(key, value []byte))
+	ForEachStorage(cb func(key, value common.Hash) bool)
 	Value() *big.Int
 }
diff --git a/core/vm/jit_test.go b/core/vm/jit_test.go
index 5fac0156f..43b1dee2a 100644
--- a/core/vm/jit_test.go
+++ b/core/vm/jit_test.go
@@ -125,17 +125,17 @@ type vmBench struct {
 
 type account struct{}
 
-func (account) SubBalance(amount *big.Int)             {}
-func (account) AddBalance(amount *big.Int)             {}
-func (account) SetAddress(common.Address)              {}
-func (account) Value() *big.Int                        { return nil }
-func (account) SetBalance(*big.Int)                    {}
-func (account) SetNonce(uint64)                        {}
-func (account) Balance() *big.Int                      { return nil }
-func (account) Address() common.Address                { return common.Address{} }
-func (account) ReturnGas(*big.Int, *big.Int)           {}
-func (account) SetCode([]byte)                         {}
-func (account) EachStorage(cb func(key, value []byte)) {}
+func (account) SubBalance(amount *big.Int)                          {}
+func (account) AddBalance(amount *big.Int)                          {}
+func (account) SetAddress(common.Address)                           {}
+func (account) Value() *big.Int                                     { return nil }
+func (account) SetBalance(*big.Int)                                 {}
+func (account) SetNonce(uint64)                                     {}
+func (account) Balance() *big.Int                                   { return nil }
+func (account) Address() common.Address                             { return common.Address{} }
+func (account) ReturnGas(*big.Int, *big.Int)                        {}
+func (account) SetCode([]byte)                                      {}
+func (account) ForEachStorage(cb func(key, value common.Hash) bool) {}
 
 func runVmBench(test vmBench, b *testing.B) {
 	var sender account
@@ -165,16 +165,16 @@ func runVmBench(test vmBench, b *testing.B) {
 type Env struct {
 	gasLimit *big.Int
 	depth    int
-	evm      *Vm
+	evm      *EVM
 }
 
 func NewEnv() *Env {
 	env := &Env{gasLimit: big.NewInt(10000), depth: 0}
-	env.evm = EVM(env)
+	env.evm = New(env, nil)
 	return env
 }
 
-func (self *Env) Vm() *Vm                { return self.evm }
+func (self *Env) Vm() Vm                 { return self.evm }
 func (self *Env) Origin() common.Address { return common.Address{} }
 func (self *Env) BlockNumber() *big.Int  { return big.NewInt(0) }
 func (self *Env) AddStructLog(log StructLog) {
diff --git a/core/vm/logger.go b/core/vm/logger.go
index 2bd02319f..8d333dfd2 100644
--- a/core/vm/logger.go
+++ b/core/vm/logger.go
@@ -18,12 +18,143 @@ package vm
 
 import (
 	"fmt"
+	"math/big"
 	"os"
 	"unicode"
 
 	"github.com/ethereum/go-ethereum/common"
 )
 
+type Storage map[common.Hash]common.Hash
+
+func (self Storage) Copy() Storage {
+	cpy := make(Storage)
+	for key, value := range self {
+		cpy[key] = value
+	}
+
+	return cpy
+}
+
+// StructLogCollector is the basic interface to capture emited logs by the EVM logger.
+type StructLogCollector interface {
+	// Adds the structured log to the collector.
+	AddStructLog(StructLog)
+}
+
+// LogConfig are the configuration options for structured logger the EVM
+type LogConfig struct {
+	DisableMemory  bool               // disable memory capture
+	DisableStack   bool               // disable stack capture
+	DisableStorage bool               // disable storage capture
+	FullStorage    bool               // show full storage (slow)
+	Collector      StructLogCollector // the log collector
+}
+
+// StructLog is emitted to the Environment each cycle and lists information about the current internal state
+// prior to the execution of the statement.
+type StructLog struct {
+	Pc      uint64
+	Op      OpCode
+	Gas     *big.Int
+	GasCost *big.Int
+	Memory  []byte
+	Stack   []*big.Int
+	Storage map[common.Hash]common.Hash
+	Depth   int
+	Err     error
+}
+
+// Logger is an EVM state logger and implements VmLogger.
+//
+// Logger can capture state based on the given Log configuration and also keeps
+// a track record of modified storage which is used in reporting snapshots of the
+// contract their storage.
+type Logger struct {
+	cfg LogConfig
+
+	env           Environment
+	changedValues map[common.Address]Storage
+}
+
+// newLogger returns a new logger
+func newLogger(cfg LogConfig, env Environment) *Logger {
+	return &Logger{
+		cfg:           cfg,
+		env:           env,
+		changedValues: make(map[common.Address]Storage),
+	}
+}
+
+// captureState logs a new structured log message and pushes it out to the environment
+//
+// captureState also tracks SSTORE ops to track dirty values.
+func (l *Logger) captureState(pc uint64, op OpCode, gas, cost *big.Int, memory *Memory, stack *stack, contract *Contract, err error) {
+	// short circuit if no log collector is present
+	if l.cfg.Collector == nil {
+		return
+	}
+
+	// initialise new changed values storage container for this contract
+	// if not present.
+	if l.changedValues[contract.Address()] == nil {
+		l.changedValues[contract.Address()] = make(Storage)
+	}
+
+	// capture SSTORE opcodes and determine the changed value and store
+	// it in the local storage container. NOTE: we do not need to do any
+	// range checks here because that's already handler prior to calling
+	// this function.
+	switch op {
+	case SSTORE:
+		var (
+			value   = common.BigToHash(stack.data[stack.len()-2])
+			address = common.BigToHash(stack.data[stack.len()-1])
+		)
+		l.changedValues[contract.Address()][address] = value
+	}
+
+	// copy a snapstot of the current memory state to a new buffer
+	var mem []byte
+	if !l.cfg.DisableMemory {
+		mem = make([]byte, len(memory.Data()))
+		copy(mem, memory.Data())
+	}
+
+	// copy a snapshot of the current stack state to a new buffer
+	var stck []*big.Int
+	if !l.cfg.DisableStack {
+		stck = make([]*big.Int, len(stack.Data()))
+		for i, item := range stack.Data() {
+			stck[i] = new(big.Int).Set(item)
+		}
+	}
+
+	// Copy the storage based on the settings specified in the log config. If full storage
+	// is disabled (default) we can use the simple Storage.Copy method, otherwise we use
+	// the state object to query for all values (slow process).
+	var storage Storage
+	if !l.cfg.DisableStorage {
+		if l.cfg.FullStorage {
+			storage = make(Storage)
+			// Get the contract account and loop over each storage entry. This may involve looping over
+			// the trie and is a very expensive process.
+			l.env.Db().GetAccount(contract.Address()).ForEachStorage(func(key, value common.Hash) bool {
+				storage[key] = value
+				// Return true, indicating we'd like to continue.
+				return true
+			})
+		} else {
+			// copy a snapshot of the current storage to a new container.
+			storage = l.changedValues[contract.Address()].Copy()
+		}
+	}
+	// create a new snaptshot of the EVM.
+	log := StructLog{pc, op, new(big.Int).Set(gas), cost, mem, stck, storage, l.env.Depth(), err}
+	// Add the log to the collector
+	l.cfg.Collector.AddStructLog(log)
+}
+
 // StdErrFormat formats a slice of StructLogs to human readable format
 func StdErrFormat(logs []StructLog) {
 	fmt.Fprintf(os.Stderr, "VM STAT %d OPs\n", len(logs))
@@ -61,7 +192,7 @@ func StdErrFormat(logs []StructLog) {
 
 		fmt.Fprintln(os.Stderr, "STORAGE =", len(log.Storage))
 		for h, item := range log.Storage {
-			fmt.Fprintf(os.Stderr, "%x: %x\n", h, common.LeftPadBytes(item, 32))
+			fmt.Fprintf(os.Stderr, "%x: %x\n", h, item)
 		}
 		fmt.Fprintln(os.Stderr)
 	}
diff --git a/core/vm/logger_test.go b/core/vm/logger_test.go
new file mode 100644
index 000000000..77fee2c64
--- /dev/null
+++ b/core/vm/logger_test.go
@@ -0,0 +1,104 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package vm
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+)
+
+type dummyContractRef struct {
+	calledForEach bool
+}
+
+func (dummyContractRef) ReturnGas(*big.Int, *big.Int) {}
+func (dummyContractRef) Address() common.Address      { return common.Address{} }
+func (dummyContractRef) Value() *big.Int              { return new(big.Int) }
+func (dummyContractRef) SetCode([]byte)               {}
+func (d *dummyContractRef) ForEachStorage(callback func(key, value common.Hash) bool) {
+	d.calledForEach = true
+}
+func (d *dummyContractRef) SubBalance(amount *big.Int) {}
+func (d *dummyContractRef) AddBalance(amount *big.Int) {}
+func (d *dummyContractRef) SetBalance(*big.Int)        {}
+func (d *dummyContractRef) SetNonce(uint64)            {}
+func (d *dummyContractRef) Balance() *big.Int          { return new(big.Int) }
+
+type dummyEnv struct {
+	*Env
+	ref *dummyContractRef
+}
+
+func newDummyEnv(ref *dummyContractRef) *dummyEnv {
+	return &dummyEnv{
+		Env: NewEnv(),
+		ref: ref,
+	}
+}
+func (d dummyEnv) GetAccount(common.Address) Account {
+	return d.ref
+}
+func (d dummyEnv) AddStructLog(StructLog) {}
+
+func TestStoreCapture(t *testing.T) {
+	var (
+		env      = NewEnv()
+		logger   = newLogger(LogConfig{Collector: env}, env)
+		mem      = NewMemory()
+		stack    = newstack()
+		contract = NewContract(&dummyContractRef{}, &dummyContractRef{}, new(big.Int), new(big.Int), new(big.Int))
+	)
+	stack.push(big.NewInt(1))
+	stack.push(big.NewInt(0))
+
+	var index common.Hash
+
+	logger.captureState(0, SSTORE, new(big.Int), new(big.Int), mem, stack, contract, nil)
+	if len(logger.changedValues[contract.Address()]) == 0 {
+		t.Fatalf("expected exactly 1 changed value on address %x, got %d", contract.Address(), len(logger.changedValues[contract.Address()]))
+	}
+
+	exp := common.BigToHash(big.NewInt(1))
+	if logger.changedValues[contract.Address()][index] != exp {
+		t.Errorf("expected %x, got %x", exp, logger.changedValues[contract.Address()][index])
+	}
+}
+
+func TestStorageCapture(t *testing.T) {
+	t.Skip("implementing this function is difficult. it requires all sort of interfaces to be implemented which isn't trivial. The value (the actual test) isn't worth it")
+	var (
+		ref      = &dummyContractRef{}
+		contract = NewContract(ref, ref, new(big.Int), new(big.Int), new(big.Int))
+		env      = newDummyEnv(ref)
+		logger   = newLogger(LogConfig{Collector: env}, env)
+		mem      = NewMemory()
+		stack    = newstack()
+	)
+
+	logger.captureState(0, STOP, new(big.Int), new(big.Int), mem, stack, contract, nil)
+	if ref.calledForEach {
+		t.Error("didn't expect for each to be called")
+	}
+
+	logger = newLogger(LogConfig{Collector: env, FullStorage: true}, env)
+	logger.captureState(0, STOP, new(big.Int), new(big.Int), mem, stack, contract, nil)
+	if !ref.calledForEach {
+		t.Error("expected for each to be called")
+	}
+}
diff --git a/core/vm/runtime/env.go b/core/vm/runtime/env.go
index e9bf828ea..ce64d7117 100644
--- a/core/vm/runtime/env.go
+++ b/core/vm/runtime/env.go
@@ -42,7 +42,7 @@ type Env struct {
 
 	getHashFn func(uint64) common.Hash
 
-	evm *vm.Vm
+	evm *vm.EVM
 }
 
 // NewEnv returns a new vm.Environment
@@ -56,7 +56,15 @@ func NewEnv(cfg *Config, state *state.StateDB) vm.Environment {
 		difficulty: cfg.Difficulty,
 		gasLimit:   cfg.GasLimit,
 	}
-	env.evm = vm.EVM(env)
+	env.evm = vm.New(env, &vm.Config{
+		Debug:     cfg.Debug,
+		EnableJit: !cfg.DisableJit,
+		ForceJit:  !cfg.DisableJit,
+
+		Logger: vm.LogConfig{
+			Collector: env,
+		},
+	})
 
 	return env
 }
@@ -69,7 +77,7 @@ func (self *Env) AddStructLog(log vm.StructLog) {
 	self.logs = append(self.logs, log)
 }
 
-func (self *Env) Vm() *vm.Vm               { return self.evm }
+func (self *Env) Vm() vm.Vm                { return self.evm }
 func (self *Env) Origin() common.Address   { return self.origin }
 func (self *Env) BlockNumber() *big.Int    { return self.number }
 func (self *Env) Coinbase() common.Address { return self.coinbase }
diff --git a/core/vm/runtime/runtime.go b/core/vm/runtime/runtime.go
index 3e6057142..f88a20170 100644
--- a/core/vm/runtime/runtime.go
+++ b/core/vm/runtime/runtime.go
@@ -22,7 +22,6 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
-	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
 )
@@ -84,17 +83,6 @@ func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
 	}
 	setDefaults(cfg)
 
-	// defer the call to setting back the original values
-	defer func(debug, forceJit, enableJit bool) {
-		vm.Debug = debug
-		vm.ForceJit = forceJit
-		vm.EnableJit = enableJit
-	}(vm.Debug, vm.ForceJit, vm.EnableJit)
-
-	vm.ForceJit = !cfg.DisableJit
-	vm.EnableJit = !cfg.DisableJit
-	vm.Debug = cfg.Debug
-
 	if cfg.State == nil {
 		db, _ := ethdb.NewMemDatabase()
 		cfg.State, _ = state.New(common.Hash{}, db)
@@ -117,9 +105,6 @@ func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
 		cfg.Value,
 	)
 
-	if cfg.Debug {
-		vm.StdErrFormat(vmenv.StructLogs())
-	}
 	return ret, cfg.State, err
 }
 
@@ -131,17 +116,6 @@ func Execute(code, input []byte, cfg *Config) ([]byte, *state.StateDB, error) {
 func Call(address common.Address, input []byte, cfg *Config) ([]byte, error) {
 	setDefaults(cfg)
 
-	// defer the call to setting back the original values
-	defer func(debug, forceJit, enableJit bool) {
-		vm.Debug = debug
-		vm.ForceJit = forceJit
-		vm.EnableJit = enableJit
-	}(vm.Debug, vm.ForceJit, vm.EnableJit)
-
-	vm.ForceJit = !cfg.DisableJit
-	vm.EnableJit = !cfg.DisableJit
-	vm.Debug = cfg.Debug
-
 	vmenv := NewEnv(cfg, cfg.State)
 
 	sender := cfg.State.GetOrNewStateObject(cfg.Origin)
@@ -155,8 +129,5 @@ func Call(address common.Address, input []byte, cfg *Config) ([]byte, error) {
 		cfg.Value,
 	)
 
-	if cfg.Debug {
-		vm.StdErrFormat(vmenv.StructLogs())
-	}
 	return ret, err
 }
diff --git a/core/vm/runtime/runtime_test.go b/core/vm/runtime/runtime_test.go
index e5183052f..88c76c731 100644
--- a/core/vm/runtime/runtime_test.go
+++ b/core/vm/runtime/runtime_test.go
@@ -117,21 +117,6 @@ func TestCall(t *testing.T) {
 	}
 }
 
-func TestRestoreDefaults(t *testing.T) {
-	Execute(nil, nil, &Config{Debug: true})
-	if vm.ForceJit {
-		t.Error("expected force jit to be disabled")
-	}
-
-	if vm.Debug {
-		t.Error("expected debug to be disabled")
-	}
-
-	if vm.EnableJit {
-		t.Error("expected jit to be disabled")
-	}
-}
-
 func BenchmarkCall(b *testing.B) {
 	var definition = `[{"constant":true,"inputs":[],"name":"seller","outputs":[{"name":"","type":"address"}],"type":"function"},{"constant":false,"inputs":[],"name":"abort","outputs":[],"type":"function"},{"constant":true,"inputs":[],"name":"value","outputs":[{"name":"","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[],"name":"refund","outputs":[],"type":"function"},{"constant":true,"inputs":[],"name":"buyer","outputs":[{"name":"","type":"address"}],"type":"function"},{"constant":false,"inputs":[],"name":"confirmReceived","outputs":[],"type":"function"},{"constant":true,"inputs":[],"name":"state","outputs":[{"name":"","type":"uint8"}],"type":"function"},{"constant":false,"inputs":[],"name":"confirmPurchase","outputs":[],"type":"function"},{"inputs":[],"type":"constructor"},{"anonymous":false,"inputs":[],"name":"Aborted","type":"event"},{"anonymous":false,"inputs":[],"name":"PurchaseConfirmed","type":"event"},{"anonymous":false,"inputs":[],"name":"ItemReceived","type":"event"},{"anonymous":false,"inputs":[],"name":"Refunded","type":"event"}]`
 
diff --git a/core/vm/virtual_machine.go b/core/vm/virtual_machine.go
index 9b3340bb2..629108884 100644
--- a/core/vm/virtual_machine.go
+++ b/core/vm/virtual_machine.go
@@ -18,6 +18,5 @@ package vm
 
 // VirtualMachine is an EVM interface
 type VirtualMachine interface {
-	Env() Environment
 	Run(*Contract, []byte) ([]byte, error)
 }
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 26df8aef4..f72c853a2 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -28,24 +28,54 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
-// Vm is an EVM and implements VirtualMachine
-type Vm struct {
+// Config are the configuration options for the EVM
+type Config struct {
+	Debug     bool
+	EnableJit bool
+	ForceJit  bool
+	Logger    LogConfig
+}
+
+// EVM is used to run Ethereum based contracts and will utilise the
+// passed environment to query external sources for state information.
+// The EVM will run the byte code VM or JIT VM based on the passed
+// configuration.
+type EVM struct {
 	env       Environment
 	jumpTable vmJumpTable
+	cfg       *Config
+
+	logger *Logger
 }
 
-func EVM(env Environment) *Vm {
-	return &Vm{env: env, jumpTable: newJumpTable(env.BlockNumber())}
+// New returns a new instance of the EVM.
+func New(env Environment, cfg *Config) *EVM {
+	// initialise a default config if none is present
+	if cfg == nil {
+		cfg = new(Config)
+	}
+
+	var logger *Logger
+	if cfg.Debug {
+		logger = newLogger(cfg.Logger, env)
+	}
+
+	return &EVM{
+		env:       env,
+		jumpTable: newJumpTable(env.BlockNumber()),
+		cfg:       cfg,
+		logger:    logger,
+	}
 }
 
 // Run loops and evaluates the contract's code with the given input data
-func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
-	self.env.SetDepth(self.env.Depth() + 1)
-	defer self.env.SetDepth(self.env.Depth() - 1)
+func (evm *EVM) Run(contract *Contract, input []byte) (ret []byte, err error) {
+	evm.env.SetDepth(evm.env.Depth() + 1)
+	defer evm.env.SetDepth(evm.env.Depth() - 1)
 
 	if contract.CodeAddr != nil {
 		if p := Precompiled[contract.CodeAddr.Str()]; p != nil {
-			return self.RunPrecompiled(p, input, contract)
+			return evm.RunPrecompiled(p, input, contract)
 		}
 	}
 
@@ -58,21 +88,21 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 		codehash = crypto.Keccak256Hash(contract.Code) // codehash is used when doing jump dest caching
 		program  *Program
 	)
-	if EnableJit {
+	if evm.cfg.EnableJit {
 		// If the JIT is enabled check the status of the JIT program,
 		// if it doesn't exist compile a new program in a separate
 		// goroutine or wait for compilation to finish if the JIT is
 		// forced.
 		switch GetProgramStatus(codehash) {
 		case progReady:
-			return RunProgram(GetProgram(codehash), self.env, contract, input)
+			return RunProgram(GetProgram(codehash), evm.env, contract, input)
 		case progUnknown:
-			if ForceJit {
+			if evm.cfg.ForceJit {
 				// Create and compile program
 				program = NewProgram(contract.Code)
 				perr := CompileProgram(program)
 				if perr == nil {
-					return RunProgram(program, self.env, contract, input)
+					return RunProgram(program, evm.env, contract, input)
 				}
 				glog.V(logger.Info).Infoln("error compiling program", err)
 			} else {
@@ -95,10 +125,10 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 		code       = contract.Code
 		instrCount = 0
 
-		op      OpCode          // current opcode
-		mem     = NewMemory()   // bound memory
-		stack   = newstack()    // local stack
-		statedb = self.env.Db() // current state
+		op      OpCode         // current opcode
+		mem     = NewMemory()  // bound memory
+		stack   = newstack()   // local stack
+		statedb = evm.env.Db() // current state
 		// For optimisation reason we're using uint64 as the program counter.
 		// It's theoretically possible to go above 2^64. The YP defines the PC to be uint256. Practically much less so feasible.
 		pc = uint64(0) // program counter
@@ -123,8 +153,8 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 
 	// User defer pattern to check for an error and, based on the error being nil or not, use all gas and return.
 	defer func() {
-		if err != nil {
-			self.log(pc, op, contract.Gas, cost, mem, stack, contract, err)
+		if err != nil && evm.cfg.Debug {
+			evm.logger.captureState(pc, op, contract.Gas, cost, mem, stack, contract, err)
 		}
 	}()
 
@@ -143,7 +173,7 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 					// move execution
 					fmt.Println("moved", it)
 					glog.V(logger.Info).Infoln("Moved execution to JIT")
-					return runProgram(program, pc, mem, stack, self.env, contract, input)
+					return runProgram(program, pc, mem, stack, evm.env, contract, input)
 				}
 			}
 		*/
@@ -151,7 +181,7 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = contract.GetOp(pc)
 		// calculate the new memory size and gas price for the current executing opcode
-		newMemSize, cost, err = calculateGasAndSize(self.env, contract, caller, op, statedb, mem, stack)
+		newMemSize, cost, err = calculateGasAndSize(evm.env, contract, caller, op, statedb, mem, stack)
 		if err != nil {
 			return nil, err
 		}
@@ -165,14 +195,17 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 		// Resize the memory calculated previously
 		mem.Resize(newMemSize.Uint64())
 		// Add a log message
-		self.log(pc, op, contract.Gas, cost, mem, stack, contract, nil)
-		if opPtr := self.jumpTable[op]; opPtr.valid {
+		if evm.cfg.Debug {
+			evm.logger.captureState(pc, op, contract.Gas, cost, mem, stack, contract, nil)
+		}
+
+		if opPtr := evm.jumpTable[op]; opPtr.valid {
 			if opPtr.fn != nil {
-				opPtr.fn(instruction{}, &pc, self.env, contract, mem, stack)
+				opPtr.fn(instruction{}, &pc, evm.env, contract, mem, stack)
 			} else {
 				switch op {
 				case PC:
-					opPc(instruction{data: new(big.Int).SetUint64(pc)}, &pc, self.env, contract, mem, stack)
+					opPc(instruction{data: new(big.Int).SetUint64(pc)}, &pc, evm.env, contract, mem, stack)
 				case JUMP:
 					if err := jump(pc, stack.pop()); err != nil {
 						return nil, err
@@ -195,7 +228,7 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 
 					return ret, nil
 				case SUICIDE:
-					opSuicide(instruction{}, nil, self.env, contract, mem, stack)
+					opSuicide(instruction{}, nil, evm.env, contract, mem, stack)
 
 					fallthrough
 				case STOP: // Stop the contract
@@ -347,7 +380,7 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 }
 
 // RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
-func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, contract *Contract) (ret []byte, err error) {
+func (evm *EVM) RunPrecompiled(p *PrecompiledAccount, input []byte, contract *Contract) (ret []byte, err error) {
 	gas := p.Gas(len(input))
 	if contract.UseGas(gas) {
 		ret = p.Call(input)
@@ -357,27 +390,3 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, contract *Co
 		return nil, OutOfGasError
 	}
 }
-
-// log emits a log event to the environment for each opcode encountered. This is not to be confused with the
-// LOG* opcode.
-func (self *Vm) log(pc uint64, op OpCode, gas, cost *big.Int, memory *Memory, stack *stack, contract *Contract, err error) {
-	if Debug || GenerateStructLogs {
-		mem := make([]byte, len(memory.Data()))
-		copy(mem, memory.Data())
-
-		stck := make([]*big.Int, len(stack.Data()))
-		for i, item := range stack.Data() {
-			stck[i] = new(big.Int).Set(item)
-		}
-		storage := make(map[common.Hash][]byte)
-		contract.self.EachStorage(func(k, v []byte) {
-			storage[common.BytesToHash(k)] = v
-		})
-		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), cost, mem, stck, storage, err})
-	}
-}
-
-// Environment returns the current workable state of the VM
-func (self *Vm) Env() Environment {
-	return self.env
-}
diff --git a/core/vm/vm_jit_fake.go b/core/vm/vm_jit_fake.go
index 192f3615d..b26cf1ad0 100644
--- a/core/vm/vm_jit_fake.go
+++ b/core/vm/vm_jit_fake.go
@@ -22,5 +22,5 @@ import "fmt"
 
 func NewJitVm(env Environment) VirtualMachine {
 	fmt.Printf("Warning! EVM JIT not enabled.\n")
-	return EVM(env)
+	return New(env, nil)
 }
diff --git a/core/vm_env.go b/core/vm_env.go
index 0fab4a090..880baa7b0 100644
--- a/core/vm_env.go
+++ b/core/vm_env.go
@@ -41,33 +41,42 @@ func GetHashFn(ref common.Hash, chain *BlockChain) func(n uint64) common.Hash {
 }
 
 type VMEnv struct {
-	state  *state.StateDB
-	header *types.Header
-	msg    Message
-	depth  int
-	chain  *BlockChain
-	typ    vm.Type
-
-	getHashFn func(uint64) common.Hash
-	// structured logging
-	logs []vm.StructLog
-	evm  *vm.Vm
+	state *state.StateDB // State to use for executing
+	evm   *vm.EVM        // The Ethereum Virtual Machine
+	depth int            // Current execution depth
+	msg   Message        // Message appliod
+
+	header    *types.Header            // Header information
+	chain     *BlockChain              // Blockchain handle
+	logs      []vm.StructLog           // Logs for the custom structured logger
+	getHashFn func(uint64) common.Hash // getHashFn callback is used to retrieve block hashes
+
 }
 
-func NewEnv(state *state.StateDB, chain *BlockChain, msg Message, header *types.Header) *VMEnv {
+func NewEnv(state *state.StateDB, chain *BlockChain, msg Message, header *types.Header, cfg *vm.Config) *VMEnv {
 	env := &VMEnv{
 		chain:     chain,
 		state:     state,
 		header:    header,
 		msg:       msg,
-		typ:       vm.StdVmTy,
 		getHashFn: GetHashFn(header.ParentHash, chain),
 	}
-	env.evm = vm.EVM(env)
+
+	// initialise a default config if none present
+	if cfg == nil {
+		cfg = new(vm.Config)
+	}
+
+	// if no log collector is present set self as the collector
+	if cfg.Logger.Collector == nil {
+		cfg.Logger.Collector = env
+	}
+
+	env.evm = vm.New(env, cfg)
 	return env
 }
 
-func (self *VMEnv) Vm() *vm.Vm               { return self.evm }
+func (self *VMEnv) Vm() vm.Vm                { return self.evm }
 func (self *VMEnv) Origin() common.Address   { f, _ := self.msg.From(); return f }
 func (self *VMEnv) BlockNumber() *big.Int    { return self.header.Number }
 func (self *VMEnv) Coinbase() common.Address { return self.header.Coinbase }
@@ -78,8 +87,6 @@ func (self *VMEnv) Value() *big.Int          { return self.msg.Value() }
 func (self *VMEnv) Db() vm.Database          { return self.state }
 func (self *VMEnv) Depth() int               { return self.depth }
 func (self *VMEnv) SetDepth(i int)           { self.depth = i }
-func (self *VMEnv) VmType() vm.Type          { return self.typ }
-func (self *VMEnv) SetVmType(t vm.Type)      { self.typ = t }
 func (self *VMEnv) GetHash(n uint64) common.Hash {
 	return self.getHashFn(n)
 }