Add wallet API to set better earliest block height.

sockets.go

@@ -597,6 +597,11 @@ func NotifyNewBlockChainHeight(reply chan []byte, height int32) {
 
 // NtfnBlockConnected handles btcd notifications resulting from newly
 // connected blocks to the main blockchain.
+//
+// TODO(jrick): Send block time with notification.  This will be used
+// to mark wallet files with a possibly-better earliest block height,
+// and will greatly reduce rescan times for wallets created with an
+// out of sync btcd.
 func NtfnBlockConnected(n btcws.Notification) {
 	bcn, ok := n.(*btcws.BlockConnectedNtfn)
 	if !ok {

wallet/wallet.go

@@ -1090,6 +1090,16 @@ func (w *Wallet) EarliestBlockHeight() int32 {
 	return height
 }
 
+// SetBetterEarliestBlockHeight sets a better earliest block height.
+// At wallet creation time, a earliest block is guessed, but this
+// could be incorrect if btcd is out of sync.  This function can be
+// used to correct a previous guess with a better value.
+func (w *Wallet) SetBetterEarliestBlockHeight(height int32) {
+	if height > w.keyGenerator.firstBlock {
+		w.keyGenerator.firstBlock = height
+	}
+}
+
 // ImportPrivateKey creates a new encrypted btcAddress with a
 // user-provided private key and adds it to the wallet.  If the
 // import is successful, the payment address string is returned.
@@ -1136,6 +1146,13 @@ func (w *Wallet) ImportPrivateKey(privkey []byte, compressed bool,
 	return addrstr, nil
 }
 
+// CreateDate returns the Unix time of the wallet creation time.  This
+// is used to compare the wallet creation time against block headers and
+// set a better minimum block height of where to being rescans.
+func (w *Wallet) CreateDate() int64 {
+	return w.createDate
+}
+
 // AddressInfo holds information regarding an address needed to manage
 // a complete wallet.
 type AddressInfo struct {