From 0b12010d843dc322128807a55f9ae4e2e5747775 Mon Sep 17 00:00:00 2001
From: Nick Johnson <arachnid@notdot.net>
Date: Mon, 31 Oct 2016 12:09:26 +0000
Subject: [PATCH] eth/trie: Implement upgrade process for direct cache

---
 eth/db_upgrade.go   | 30 +++++++++++++++++++++++++++++-
 trie/directcache.go | 18 +++++++++---------
 2 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/eth/db_upgrade.go b/eth/db_upgrade.go
index d53ca2930f..6e2657e010 100644
--- a/eth/db_upgrade.go
+++ b/eth/db_upgrade.go
@@ -26,11 +26,13 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/ethereum/go-ethereum/trie"
 )
 
 var useSequentialKeys = []byte("dbUpgrade_20160530sequentialKeys")
@@ -355,6 +357,32 @@ func addMipmapBloomBins(db ethdb.Database) (err error) {
 	return nil
 }
 
-func populateDirectCache(db ethdb.Database, blockchain *core.BlockChain) error {
+func populateDirectCache(db ethdb.Database, bc *core.BlockChain) error {
+	blockHash, status := trie.GetMigrationState(state.DirectCachePrefix, db)
+	if status == trie.NotStarted {
+		blockHash = core.GetHeadBlockHash(db)
+		status = trie.Running
+		trie.SetMigrationState(state.DirectCachePrefix, blockHash, status, db)
+	}
+	blockNum := core.GetBlockNumber(db, blockHash)
+
+	if status == trie.Running {
+		tr, err := trie.New(core.GetBlock(db, blockHash, blockNum).Root(), db, 0)
+		if err != nil {
+			return err
+		}
+		dc := trie.NewDirectCache(tr, db, state.DirectCachePrefix, blockNum, blockHash, bc, false)
+		go func() {
+			for core.GetBlockNumber(db, core.GetHeadBlockHash(db)) < blockNum + 8 {
+				time.Sleep(10 * time.Second)
+			}
+			glog.Infof("Beginning direct cache upgrade at block %v", blockNum)
+
+			if err := dc.Populate(); err != nil {
+				glog.Errorf("Direct cache upgrade failed: %v", err)
+			}
+			trie.SetMigrationState(state.DirectCachePrefix, blockHash, trie.Complete, db)
+		}()
+	}
 	return nil
 }
diff --git a/trie/directcache.go b/trie/directcache.go
index 89825615b3..c7e114c1bc 100644
--- a/trie/directcache.go
+++ b/trie/directcache.go
@@ -189,7 +189,7 @@ func (dc *DirectCache) Populate() (err error) {
 	it := dc.Iterator()
 	for it.Next() {
 		if err := DirectCacheTransaction(func() error {
-			if HasDirectCache(dc.keyPrefix, it.Key, dc.db) {
+			if !HasDirectCache(dc.keyPrefix, it.Key, dc.db) {
 				writes += 1
 				if err = WriteDirectCache(dc.keyPrefix, it.Key, it.Value, dc.blockNum, dc.blockHash, dc.db); err != nil {
 					return err
@@ -202,7 +202,7 @@ func (dc *DirectCache) Populate() (err error) {
 
 		i += 1
 		if i % 10000 == 0 && glog.V(logger.Info) {
-			glog.V(logger.Info).Infof("Constructing direct cache: processed %v entries, writing %v", i, writes)
+			glog.V(logger.Info).Infof("Constructing direct cache: processed %v entries, written %v", i, writes)
 		}
 	}
 	return nil
@@ -271,29 +271,29 @@ func HasDirectCache(prefix, key []byte, db Database) bool {
 
 type migrationState struct {
 	Status MigrationStatus
-	Number uint64
+	Hash   common.Hash
 }
 
 // GetMigrationState returns the block number of the migration to the direct cache, and
 // whether or not it's complete.
-func GetMigrationState(prefix []byte, db Database) (uint64, MigrationStatus) {
+func GetMigrationState(prefix []byte, db Database) (common.Hash, MigrationStatus) {
 	enc, _ := db.Get(append(MigrationPrefix, prefix...))
 	if len(enc) == 0 {
-		return 0, NotStarted
+		return common.Hash{}, NotStarted
 	}
 
 	var data migrationState
 	if err := rlp.DecodeBytes(enc, &data); err != nil {
 		glog.Errorf("Could not decode migration status: %v", err)
-		return 0, NotStarted
+		return common.Hash{}, NotStarted
 	}
 
-	return data.Number, data.Status
+	return data.Hash, data.Status
 }
 
 // SetMigrationState updates the migration state in the database
-func SetMigrationState(prefix []byte, blockNum uint64, status MigrationStatus, db Database) error {
-	enc, _ := rlp.EncodeToBytes(migrationState{status, blockNum})
+func SetMigrationState(prefix []byte, blockHash common.Hash, status MigrationStatus, db Database) error {
+	enc, _ := rlp.EncodeToBytes(migrationState{status, blockHash})
 	return db.Put(append(MigrationPrefix, prefix...), enc)
 }