all: integrate the freezer with fast sync

* all: freezer style syncing

core, eth, les, light: clean up freezer relative APIs

core, eth, les, trie, ethdb, light: clean a bit

core, eth, les, light: add unit tests

core, light: rewrite setHead function

core, eth: fix downloader unit tests

core: add receipt chain insertion test

core: use constant instead of hardcoding table name

core: fix rollback

core: fix setHead

core/rawdb: remove canonical block first and then iterate side chain

core/rawdb, ethdb: add hasAncient interface

eth/downloader: calculate ancient limit via cht first

core, eth, ethdb: lots of fixes

* eth/downloader: print ancient disable log only for fast sync

3 files changed, 7 insertions, 9 deletions

diff --git a/trie/database.go b/trie/database.go
index 49a696bef..d8a0fa9c5 100644
--- a/trie/database.go
+++ b/trie/database.go
@@ -321,7 +321,7 @@ func NewDatabaseWithCache(diskdb ethdb.KeyValueStore, cache int) *Database {
 }
 
 // DiskDB retrieves the persistent storage backing the trie database.
-func (db *Database) DiskDB() ethdb.Reader {
+func (db *Database) DiskDB() ethdb.KeyValueReader {
 	return db.diskdb
 }
 
diff --git a/trie/proof.go b/trie/proof.go
index 3c4b8d653..9985e730d 100644
--- a/trie/proof.go
+++ b/trie/proof.go
@@ -33,7 +33,7 @@ import (
 // If the trie does not contain a value for key, the returned proof contains all
 // nodes of the longest existing prefix of the key (at least the root node), ending
 // with the node that proves the absence of the key.
-func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.Writer) error {
+func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.KeyValueWriter) error {
 	// Collect all nodes on the path to key.
 	key = keybytesToHex(key)
 	var nodes []node
@@ -96,16 +96,14 @@ func (t *Trie) Prove(key []byte, fromLevel uint, proofDb ethdb.Writer) error {
 // If the trie does not contain a value for key, the returned proof contains all
 // nodes of the longest existing prefix of the key (at least the root node), ending
 // with the node that proves the absence of the key.
-func (t *SecureTrie) Prove(key []byte, fromLevel uint, proofDb ethdb.Writer) error {
+func (t *SecureTrie) Prove(key []byte, fromLevel uint, proofDb ethdb.KeyValueWriter) error {
 	return t.trie.Prove(key, fromLevel, proofDb)
 }
 
 // VerifyProof checks merkle proofs. The given proof must contain the value for
 // key in a trie with the given root hash. VerifyProof returns an error if the
 // proof contains invalid trie nodes or the wrong value.
-//
-// Note, the method assumes that all key-values in proofDb satisfy key = hash(value).
-func VerifyProof(rootHash common.Hash, key []byte, proofDb ethdb.Reader) (value []byte, nodes int, err error) {
+func VerifyProof(rootHash common.Hash, key []byte, proofDb ethdb.KeyValueReader) (value []byte, nodes int, err error) {
 	key = keybytesToHex(key)
 	wantHash := rootHash
 	for i := 0; ; i++ {
diff --git a/trie/sync.go b/trie/sync.go
index d9564d783..6f40b45a1 100644
--- a/trie/sync.go
+++ b/trie/sync.go
@@ -72,7 +72,7 @@ func newSyncMemBatch() *syncMemBatch {
 // unknown trie hashes to retrieve, accepts node data associated with said hashes
 // and reconstructs the trie step by step until all is done.
 type Sync struct {
-	database ethdb.Reader             // Persistent database to check for existing entries
+	database ethdb.KeyValueReader     // Persistent database to check for existing entries
 	membatch *syncMemBatch            // Memory buffer to avoid frequent database writes
 	requests map[common.Hash]*request // Pending requests pertaining to a key hash
 	queue    *prque.Prque             // Priority queue with the pending requests
@@ -80,7 +80,7 @@ type Sync struct {
 }
 
 // NewSync creates a new trie data download scheduler.
-func NewSync(root common.Hash, database ethdb.Reader, callback LeafCallback, bloom *SyncBloom) *Sync {
+func NewSync(root common.Hash, database ethdb.KeyValueReader, callback LeafCallback, bloom *SyncBloom) *Sync {
 	ts := &Sync{
 		database: database,
 		membatch: newSyncMemBatch(),
@@ -224,7 +224,7 @@ func (s *Sync) Process(results []SyncResult) (bool, int, error) {
 
 // Commit flushes the data stored in the internal membatch out to persistent
 // storage, returning the number of items written and any occurred error.
-func (s *Sync) Commit(dbw ethdb.Writer) (int, error) {
+func (s *Sync) Commit(dbw ethdb.KeyValueWriter) (int, error) {
 	// Dump the membatch into a database dbw
 	for i, key := range s.membatch.order {
 		if err := dbw.Put(key[:], s.membatch.batch[key]); err != nil {