consensus, core/*, params: metropolis preparation refactor

This commit is a preparation for the upcoming metropolis hardfork. It
prepares the state, core and vm packages such that integration with
metropolis becomes less of a hassle.

* Difficulty calculation requires header instead of individual
  parameters
* statedb.StartRecord renamed to statedb.Prepare and added Finalise
  method required by metropolis, which removes unwanted accounts from
  the state (i.e. selfdestruct)
* State keeps record of destructed objects (in addition to dirty
  objects)
* core/vm pre-compiles may now return errors
* core/vm pre-compiles gas check now take the full byte slice as argument
  instead of just the size
* core/vm now keeps several hard-fork instruction tables instead of a
  single instruction table and removes the need for hard-fork checks in
  the instructions
* core/vm contains a empty restruction function which is added in
  preparation of metropolis write-only mode operations
* Adds the bn256 curve
* Adds and sets the metropolis chain config block parameters (2^64-1)

1 files changed, 57 insertions, 34 deletions

diff --git a/core/state/statedb.go b/core/state/statedb.go
index 3b753a2e6..8e4ba21c0 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -62,8 +62,9 @@ type StateDB struct {
 	codeSizeCache *lru.Cache
 
 	// This map holds 'live' objects, which will get modified while processing a state transition.
-	stateObjects      map[common.Address]*stateObject
-	stateObjectsDirty map[common.Address]struct{}
+	stateObjects           map[common.Address]*stateObject
+	stateObjectsDirty      map[common.Address]struct{}
+	stateObjectsDestructed map[common.Address]struct{}
 
 	// The refund counter, also used by state transitioning.
 	refund *big.Int
@@ -92,14 +93,15 @@ func New(root common.Hash, db ethdb.Database) (*StateDB, error) {
 	}
 	csc, _ := lru.New(codeSizeCacheSize)
 	return &StateDB{
-		db:                db,
-		trie:              tr,
-		codeSizeCache:     csc,
-		stateObjects:      make(map[common.Address]*stateObject),
-		stateObjectsDirty: make(map[common.Address]struct{}),
-		refund:            new(big.Int),
-		logs:              make(map[common.Hash][]*types.Log),
-		preimages:         make(map[common.Hash][]byte),
+		db:                     db,
+		trie:                   tr,
+		codeSizeCache:          csc,
+		stateObjects:           make(map[common.Address]*stateObject),
+		stateObjectsDirty:      make(map[common.Address]struct{}),
+		stateObjectsDestructed: make(map[common.Address]struct{}),
+		refund:                 new(big.Int),
+		logs:                   make(map[common.Hash][]*types.Log),
+		preimages:              make(map[common.Hash][]byte),
 	}, nil
 }
 
@@ -114,14 +116,15 @@ func (self *StateDB) New(root common.Hash) (*StateDB, error) {
 		return nil, err
 	}
 	return &StateDB{
-		db:                self.db,
-		trie:              tr,
-		codeSizeCache:     self.codeSizeCache,
-		stateObjects:      make(map[common.Address]*stateObject),
-		stateObjectsDirty: make(map[common.Address]struct{}),
-		refund:            new(big.Int),
-		logs:              make(map[common.Hash][]*types.Log),
-		preimages:         make(map[common.Hash][]byte),
+		db:                     self.db,
+		trie:                   tr,
+		codeSizeCache:          self.codeSizeCache,
+		stateObjects:           make(map[common.Address]*stateObject),
+		stateObjectsDirty:      make(map[common.Address]struct{}),
+		stateObjectsDestructed: make(map[common.Address]struct{}),
+		refund:                 new(big.Int),
+		logs:                   make(map[common.Hash][]*types.Log),
+		preimages:              make(map[common.Hash][]byte),
 	}, nil
 }
 
@@ -138,6 +141,7 @@ func (self *StateDB) Reset(root common.Hash) error {
 	self.trie = tr
 	self.stateObjects = make(map[common.Address]*stateObject)
 	self.stateObjectsDirty = make(map[common.Address]struct{})
+	self.stateObjectsDestructed = make(map[common.Address]struct{})
 	self.thash = common.Hash{}
 	self.bhash = common.Hash{}
 	self.txIndex = 0
@@ -173,12 +177,6 @@ func (self *StateDB) pushTrie(t *trie.SecureTrie) {
 	}
 }
 
-func (self *StateDB) StartRecord(thash, bhash common.Hash, ti int) {
-	self.thash = thash
-	self.bhash = bhash
-	self.txIndex = ti
-}
-
 func (self *StateDB) AddLog(log *types.Log) {
 	self.journal = append(self.journal, addLogChange{txhash: self.thash})
 
@@ -510,21 +508,25 @@ func (self *StateDB) Copy() *StateDB {
 
 	// Copy all the basic fields, initialize the memory ones
 	state := &StateDB{
-		db:                self.db,
-		trie:              self.trie,
-		pastTries:         self.pastTries,
-		codeSizeCache:     self.codeSizeCache,
-		stateObjects:      make(map[common.Address]*stateObject, len(self.stateObjectsDirty)),
-		stateObjectsDirty: make(map[common.Address]struct{}, len(self.stateObjectsDirty)),
-		refund:            new(big.Int).Set(self.refund),
-		logs:              make(map[common.Hash][]*types.Log, len(self.logs)),
-		logSize:           self.logSize,
-		preimages:         make(map[common.Hash][]byte),
+		db:                     self.db,
+		trie:                   self.trie,
+		pastTries:              self.pastTries,
+		codeSizeCache:          self.codeSizeCache,
+		stateObjects:           make(map[common.Address]*stateObject, len(self.stateObjectsDirty)),
+		stateObjectsDirty:      make(map[common.Address]struct{}, len(self.stateObjectsDirty)),
+		stateObjectsDestructed: make(map[common.Address]struct{}, len(self.stateObjectsDestructed)),
+		refund:                 new(big.Int).Set(self.refund),
+		logs:                   make(map[common.Hash][]*types.Log, len(self.logs)),
+		logSize:                self.logSize,
+		preimages:              make(map[common.Hash][]byte),
 	}
 	// Copy the dirty states, logs, and preimages
 	for addr := range self.stateObjectsDirty {
 		state.stateObjects[addr] = self.stateObjects[addr].deepCopy(state, state.MarkStateObjectDirty)
 		state.stateObjectsDirty[addr] = struct{}{}
+		if self.stateObjects[addr].suicided {
+			state.stateObjectsDestructed[addr] = struct{}{}
+		}
 	}
 	for hash, logs := range self.logs {
 		state.logs[hash] = make([]*types.Log, len(logs))
@@ -590,6 +592,27 @@ func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
 	return s.trie.Hash()
 }
 
+// Prepare sets the current transaction hash and index and block hash which is
+// used when the EVM emits new state logs.
+func (self *StateDB) Prepare(thash, bhash common.Hash, ti int) {
+	self.thash = thash
+	self.bhash = bhash
+	self.txIndex = ti
+}
+
+// Finalise finalises the state by removing the self destructed objects
+// in the current stateObjectsDestructed buffer and clears the journal
+// as well as the refunds.
+//
+// Please note that Finalise is used by EIP#98 and is used instead of
+// IntermediateRoot.
+func (s *StateDB) Finalise() {
+	for addr := range s.stateObjectsDestructed {
+		s.deleteStateObject(s.stateObjects[addr])
+	}
+	s.clearJournalAndRefund()
+}
+
 // DeleteSuicides flags the suicided objects for deletion so that it
 // won't be referenced again when called / queried up on.
 //