From 936c8e19ff3db376fdd1ed53772c51c817a72112 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Thu, 23 Apr 2015 14:51:41 +0200
Subject: [PATCH] p2p/discover: store nodes in leveldb

---
 p2p/discover/node.go  | 83 ++++++++++++++++++++++++++++++++++++-------
 p2p/discover/table.go |  3 +-
 2 files changed, 73 insertions(+), 13 deletions(-)

diff --git a/p2p/discover/node.go b/p2p/discover/node.go
index 6662a6cb7..d8a5cc351 100644
--- a/p2p/discover/node.go
+++ b/p2p/discover/node.go
@@ -1,8 +1,10 @@
 package discover
 
 import (
+	"bytes"
 	"crypto/ecdsa"
 	"crypto/elliptic"
+	"encoding/binary"
 	"encoding/hex"
 	"errors"
 	"fmt"
@@ -11,13 +13,16 @@ import (
 	"math/rand"
 	"net"
 	"net/url"
+	"os"
 	"strconv"
 	"strings"
-	"sync"
 
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/crypto/secp256k1"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/syndtr/goleveldb/leveldb"
+	"github.com/syndtr/goleveldb/leveldb/opt"
+	"github.com/syndtr/goleveldb/leveldb/storage"
 )
 
 const nodeIDBits = 512
@@ -308,23 +313,77 @@ func randomID(a NodeID, n int) (b NodeID) {
 
 // nodeDB stores all nodes we know about.
 type nodeDB struct {
-	mu   sync.RWMutex
-	byID map[NodeID]*Node
+	ldb *leveldb.DB
+}
+
+var dbVersionKey = []byte("pv")
+
+// Opens the backing LevelDB. If path is "", we use an in-memory database.
+func newNodeDB(path string, version int64) (db *nodeDB, err error) {
+	db = new(nodeDB)
+	opts := new(opt.Options)
+	if path == "" {
+		db.ldb, err = leveldb.Open(storage.NewMemStorage(), opts)
+	} else {
+		db.ldb, err = openLDB(path, opts, version)
+	}
+	return db, err
+}
+
+func openLDB(path string, opts *opt.Options, version int64) (*leveldb.DB, error) {
+	ldb, err := leveldb.OpenFile(path, opts)
+	if _, iscorrupted := err.(leveldb.ErrCorrupted); iscorrupted {
+		ldb, err = leveldb.RecoverFile(path, opts)
+	}
+	if err != nil {
+		return nil, err
+	}
+	// The nodes contained in the database correspond to a certain
+	// protocol version. Flush all nodes if the DB version doesn't match.
+	// There is no need to do this for memory databases because they
+	// won't ever be used with a different protocol version.
+	shouldVal := make([]byte, binary.MaxVarintLen64)
+	shouldVal = shouldVal[:binary.PutVarint(shouldVal, version)]
+	val, err := ldb.Get(dbVersionKey, nil)
+	if err == leveldb.ErrNotFound {
+		err = ldb.Put(dbVersionKey, shouldVal, nil)
+	} else if err == nil && !bytes.Equal(val, shouldVal) {
+		// Delete and start over.
+		ldb.Close()
+		if err = os.RemoveAll(path); err != nil {
+			return nil, err
+		}
+		return openLDB(path, opts, version)
+	}
+	if err != nil {
+		ldb.Close()
+		ldb = nil
+	}
+	return ldb, err
 }
 
 func (db *nodeDB) get(id NodeID) *Node {
-	db.mu.RLock()
-	defer db.mu.RUnlock()
-	return db.byID[id]
+	v, err := db.ldb.Get(id[:], nil)
+	if err != nil {
+		return nil
+	}
+	n := new(Node)
+	if err := rlp.DecodeBytes(v, n); err != nil {
+		return nil
+	}
+	return n
+}
+
+func (db *nodeDB) update(n *Node) error {
+	v, err := rlp.EncodeToBytes(n)
+	if err != nil {
+		return err
+	}
+	return db.ldb.Put(n.ID[:], v, nil)
 }
 
 func (db *nodeDB) add(id NodeID, addr *net.UDPAddr, tcpPort uint16) *Node {
-	db.mu.Lock()
-	defer db.mu.Unlock()
-	if db.byID == nil {
-		db.byID = make(map[NodeID]*Node)
-	}
 	n := &Node{ID: id, IP: addr.IP, DiscPort: addr.Port, TCPPort: int(tcpPort)}
-	db.byID[n.ID] = n
+	db.update(n)
 	return n
 }
diff --git a/p2p/discover/table.go b/p2p/discover/table.go
index e2e846456..ba2f9b8ec 100644
--- a/p2p/discover/table.go
+++ b/p2p/discover/table.go
@@ -59,9 +59,10 @@ type bucket struct {
 }
 
 func newTable(t transport, ourID NodeID, ourAddr *net.UDPAddr) *Table {
+	db, _ := newNodeDB("", Version)
 	tab := &Table{
 		net:       t,
-		db:        new(nodeDB),
+		db:        db,
 		self:      newNode(ourID, ourAddr),
 		bonding:   make(map[NodeID]*bondproc),
 		bondslots: make(chan struct{}, maxBondingPingPongs),