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chain.go
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// Copyright (c) 2013-2015 The btcsuite developers
// Copyright (c) 2015-2016 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package chain
import (
"errors"
"sync"
"time"
"github.com/decred/dcrd/chaincfg"
"github.com/decred/dcrd/chaincfg/chainhash"
"github.com/decred/dcrd/dcrjson"
"github.com/decred/dcrrpcclient"
"github.com/decred/dcrutil"
"github.com/decred/dcrwallet/waddrmgr"
"github.com/decred/dcrwallet/wtxmgr"
)
// RPCClient represents a persistent client connection to a decred RPC server
// for information regarding the current best block chain.
type RPCClient struct {
*dcrrpcclient.Client
connConfig *dcrrpcclient.ConnConfig // Work around unexported field
chainParams *chaincfg.Params
reconnectAttempts int
enqueueNotification chan interface{}
dequeueNotification chan interface{}
enqueueVotingNotification chan interface{}
dequeueVotingNotification chan interface{}
currentBlock chan *waddrmgr.BlockStamp
// Information for reorganization handling.
reorganizingLock sync.Mutex
reorganizeToHash chainhash.Hash
reorganizing bool
quit chan struct{}
wg sync.WaitGroup
started bool
quitMtx sync.Mutex
}
// NewRPCClient creates a client connection to the server described by the
// connect string. If disableTLS is false, the remote RPC certificate must be
// provided in the certs slice. The connection is not established immediately,
// but must be done using the Start method. If the remote server does not
// operate on the same bitcoin network as described by the passed chain
// parameters, the connection will be disconnected.
func NewRPCClient(chainParams *chaincfg.Params, connect, user, pass string, certs []byte,
disableTLS bool, reconnectAttempts int) (*RPCClient, error) {
if reconnectAttempts < 0 {
return nil, errors.New("reconnectAttempts must be positive")
}
client := &RPCClient{
connConfig: &dcrrpcclient.ConnConfig{
Host: connect,
Endpoint: "ws",
User: user,
Pass: pass,
Certificates: certs,
DisableAutoReconnect: true,
DisableConnectOnNew: true,
DisableTLS: disableTLS,
},
reorganizeToHash: chainhash.Hash{},
reorganizing: false,
chainParams: chainParams,
reconnectAttempts: reconnectAttempts,
enqueueNotification: make(chan interface{}),
dequeueNotification: make(chan interface{}),
enqueueVotingNotification: make(chan interface{}),
dequeueVotingNotification: make(chan interface{}),
currentBlock: make(chan *waddrmgr.BlockStamp),
quit: make(chan struct{}),
}
ntfnCallbacks := &dcrrpcclient.NotificationHandlers{
OnClientConnected: client.onClientConnect,
OnBlockConnected: client.onBlockConnected,
OnBlockDisconnected: client.onBlockDisconnected,
OnReorganization: client.onReorganization,
OnWinningTickets: client.onWinningTickets,
OnSpentAndMissedTickets: client.onSpentAndMissedTickets,
OnStakeDifficulty: client.onStakeDifficulty,
OnRecvTx: client.onRecvTx,
OnRedeemingTx: client.onRedeemingTx,
OnRescanFinished: client.onRescanFinished,
OnRescanProgress: client.onRescanProgress,
}
rpcClient, err := dcrrpcclient.New(client.connConfig, ntfnCallbacks)
if err != nil {
return nil, err
}
client.Client = rpcClient
return client, nil
}
// Start attempts to establish a client connection with the remote server.
// If successful, handler goroutines are started to process notifications
// sent by the server. After a limited number of connection attempts, this
// function gives up, and therefore will not block forever waiting for the
// connection to be established to a server that may not exist.
func (c *RPCClient) Start() error {
err := c.Connect(c.reconnectAttempts)
if err != nil {
return err
}
// Verify that the server is running on the expected network.
net, err := c.GetCurrentNet()
if err != nil {
c.Disconnect()
return err
}
if net != c.chainParams.Net {
c.Disconnect()
return errors.New("mismatched networks")
}
c.quitMtx.Lock()
c.started = true
c.quitMtx.Unlock()
c.wg.Add(2)
go c.handler()
go c.handlerVoting()
return nil
}
// Stop disconnects the client and signals the shutdown of all goroutines
// started by Start.
func (c *RPCClient) Stop() {
c.quitMtx.Lock()
select {
case <-c.quit:
default:
close(c.quit)
c.Client.Shutdown()
if !c.started {
close(c.dequeueNotification)
close(c.dequeueVotingNotification)
}
}
c.quitMtx.Unlock()
}
// WaitForShutdown blocks until both the client has finished disconnecting
// and all handlers have exited.
func (c *RPCClient) WaitForShutdown() {
c.Client.WaitForShutdown()
c.wg.Wait()
}
// Notification types. These are defined here and processed from from reading
// a notificationChan to avoid handling these notifications directly in
// dcrrpcclient callbacks, which isn't very Go-like and doesn't allow
// blocking client calls.
type (
// ClientConnected is a notification for when a client connection is
// opened or reestablished to the chain server.
ClientConnected struct{}
// BlockConnected is a notification for a newly-attached block to the
// best chain.
BlockConnected wtxmgr.BlockMeta
// BlockDisconnected is a notifcation that the block described by the
// BlockStamp was reorganized out of the best chain.
BlockDisconnected wtxmgr.BlockMeta
Reorganization struct {
OldHash *chainhash.Hash
OldHeight int64
NewHash *chainhash.Hash
NewHeight int64
}
WinningTickets struct {
BlockHash *chainhash.Hash
BlockHeight int64
Tickets []*chainhash.Hash
}
MissedTickets struct {
BlockHash *chainhash.Hash
BlockHeight int64
Tickets []*chainhash.Hash
}
StakeDifficulty struct {
BlockHash *chainhash.Hash
BlockHeight int64
StakeDiff int64
}
// RelevantTx is a notification for a transaction which spends wallet
// inputs or pays to a watched address.
RelevantTx struct {
TxRecord *wtxmgr.TxRecord
Block *wtxmgr.BlockMeta // nil if unmined
}
// RescanProgress is a notification describing the current status
// of an in-progress rescan.
RescanProgress struct {
Hash *chainhash.Hash
Height int32
Time time.Time
}
// RescanFinished is a notification that a previous rescan request
// has finished.
RescanFinished struct {
Hash *chainhash.Hash
Height int32
Time time.Time
}
)
// SetReorganizing allows you to set the flag for blockchain reorganization.
func (c *RPCClient) SetReorganizingState(is bool, hash chainhash.Hash) {
c.reorganizingLock.Lock()
defer c.reorganizingLock.Unlock()
c.reorganizing = is
c.reorganizeToHash = hash
}
// SetReorganizing allows you to set the flag for blockchain reorganization.
func (c *RPCClient) GetReorganizing() (bool, chainhash.Hash) {
c.reorganizingLock.Lock()
defer c.reorganizingLock.Unlock()
return c.reorganizing, c.reorganizeToHash
}
// Notifications returns a channel of parsed notifications sent by the remote
// decred RPC server. This channel must be continually read or the process
// may abort for running out memory, as unread notifications are queued for
// later reads.
func (c *RPCClient) Notifications() <-chan interface{} {
return c.dequeueNotification
}
// NotificationsVoting returns a channel of parsed voting notifications sent
// by the remote RPC server. This channel must be continually read or the
// process may abort for running out memory, as unread notifications are
// queued for later reads.
func (c *RPCClient) NotificationsVoting() <-chan interface{} {
return c.dequeueVotingNotification
}
// BlockStamp returns the latest block notified by the client, or an error
// if the client has been shut down.
func (c *RPCClient) BlockStamp() (*waddrmgr.BlockStamp, error) {
select {
case bs := <-c.currentBlock:
return bs, nil
case <-c.quit:
return nil, errors.New("disconnected")
}
}
// parseBlock parses a dcrws definition of the block a tx is mined it to the
// Block structure of the wtxmgr package, and the block index. This is done
// here since dcrrpcclient doesn't parse this nicely for us.
func parseBlock(block *dcrjson.BlockDetails) (*wtxmgr.BlockMeta, error) {
if block == nil {
return nil, nil
}
blksha, err := chainhash.NewHashFromStr(block.Hash)
if err != nil {
return nil, err
}
blk := &wtxmgr.BlockMeta{
Block: wtxmgr.Block{
Height: block.Height,
Hash: *blksha,
},
Time: time.Unix(block.Time, 0),
VoteBits: block.VoteBits,
}
return blk, nil
}
func (c *RPCClient) onClientConnect() {
select {
case c.enqueueNotification <- ClientConnected{}:
case <-c.quit:
}
}
func (c *RPCClient) onBlockConnected(hash *chainhash.Hash, height int32, time time.Time, voteBits uint16) {
select {
case c.enqueueNotification <- BlockConnected{
Block: wtxmgr.Block{
Hash: *hash,
Height: height,
},
VoteBits: voteBits,
Time: time,
}:
case <-c.quit:
}
}
func (c *RPCClient) onBlockDisconnected(hash *chainhash.Hash, height int32, time time.Time, voteBits uint16) {
select {
case c.enqueueNotification <- BlockDisconnected{
Block: wtxmgr.Block{
Hash: *hash,
Height: height,
},
VoteBits: voteBits,
Time: time,
}:
case <-c.quit:
}
}
// onReorganization handles reorganization notifications and passes them
// downstream to the notifications queue.
func (c *RPCClient) onReorganization(oldHash *chainhash.Hash, oldHeight int32,
newHash *chainhash.Hash, newHeight int32) {
c.enqueueNotification <- Reorganization{
oldHash,
int64(oldHeight),
newHash,
int64(newHeight),
}
}
// onWinningTickets handles winning tickets notifications data and passes it
// downstream to the notifications queue.
func (c *RPCClient) onWinningTickets(hash *chainhash.Hash, height int64,
tickets []*chainhash.Hash) {
c.enqueueVotingNotification <- WinningTickets{
hash,
height,
tickets,
}
}
// onSpentAndMissedTickets handles missed tickets notifications data and passes it
// downstream to the notifications queue.
func (c *RPCClient) onSpentAndMissedTickets(hash *chainhash.Hash,
height int64,
stakeDiff int64,
tickets map[chainhash.Hash]bool) {
missedTickets := make([]*chainhash.Hash, 0)
// Copy the missing ticket hashes to a slice.
for ticket, isSpent := range tickets {
newTicket := ticket
if !isSpent { // if missed
missedTickets = append(missedTickets, &newTicket)
}
}
c.enqueueVotingNotification <- MissedTickets{
hash,
height,
missedTickets,
}
}
// onStakeDifficulty handles stake difficulty notifications data and passes it
// downstream to the notification queue.
func (c *RPCClient) onStakeDifficulty(hash *chainhash.Hash,
height int64,
stakeDiff int64) {
c.enqueueNotification <- StakeDifficulty{
hash,
height,
stakeDiff,
}
}
func (c *RPCClient) onRecvTx(tx *dcrutil.Tx, block *dcrjson.BlockDetails) {
blk, err := parseBlock(block)
if err != nil {
// Log and drop improper notification.
log.Errorf("recvtx notification bad block: %v", err)
return
}
rec, err := wtxmgr.NewTxRecordFromMsgTx(tx.MsgTx(), time.Now())
if err != nil {
log.Errorf("Cannot create transaction record for relevant "+
"tx: %v", err)
return
}
select {
case c.enqueueNotification <- RelevantTx{rec, blk}:
case <-c.quit:
}
}
func (c *RPCClient) onRedeemingTx(tx *dcrutil.Tx, block *dcrjson.BlockDetails) {
// Handled exactly like recvtx notifications.
c.onRecvTx(tx, block)
}
func (c *RPCClient) onRescanProgress(hash *chainhash.Hash, height int32, blkTime time.Time) {
select {
case c.enqueueNotification <- &RescanProgress{hash, height, blkTime}:
case <-c.quit:
}
}
func (c *RPCClient) onRescanFinished(hash *chainhash.Hash, height int32, blkTime time.Time) {
select {
case c.enqueueNotification <- &RescanFinished{hash, height, blkTime}:
case <-c.quit:
}
}
// handler maintains a queue of notifications and the current state (best
// block) of the chain.
func (c *RPCClient) handler() {
hash, height, err := c.GetBestBlock()
if err != nil {
log.Errorf("Failed to receive best block from chain server: %v", err)
c.Stop()
c.wg.Done()
return
}
bs := &waddrmgr.BlockStamp{Hash: *hash, Height: height}
// TODO: Rather than leaving this as an unbounded queue for all types of
// notifications, try dropping ones where a later enqueued notification
// can fully invalidate one waiting to be processed. For example,
// blockconnected notifications for greater block heights can remove the
// need to process earlier blockconnected notifications still waiting
// here.
var notifications []interface{}
enqueue := c.enqueueNotification
var dequeue chan interface{}
var next interface{}
pingChan := time.After(time.Minute)
out:
for {
select {
case n, ok := <-enqueue:
if !ok {
// If no notifications are queued for handling,
// the queue is finished.
if len(notifications) == 0 {
break out
}
// nil channel so no more reads can occur.
enqueue = nil
continue
}
if len(notifications) == 0 {
next = n
dequeue = c.dequeueNotification
}
notifications = append(notifications, n)
pingChan = time.After(time.Minute)
case dequeue <- next:
if n, ok := next.(BlockConnected); ok {
bs = &waddrmgr.BlockStamp{
Height: n.Height,
Hash: n.Hash,
}
}
notifications[0] = nil
notifications = notifications[1:]
if len(notifications) != 0 {
next = notifications[0]
} else {
// If no more notifications can be enqueued, the
// queue is finished.
if enqueue == nil {
break out
}
dequeue = nil
}
case <-pingChan:
// No notifications were received in the last 60s.
// Ensure the connection is still active by making a new
// request to the server.
// TODO: A minute timeout is used to prevent the handler
// loop from blocking here forever, but this is much larger
// than it needs to be due to dcrd processing websocket
// requests synchronously (see
// https://github.com/btcsuite/btcd/issues/504). Decrease
// this to something saner like 3s when the above issue is
// fixed.
type sessionResult struct {
err error
}
sessionResponse := make(chan sessionResult, 1)
go func() {
_, err := c.Session()
sessionResponse <- sessionResult{err}
}()
select {
case resp := <-sessionResponse:
if resp.err != nil {
log.Errorf("Failed to receive session "+
"result: %v", resp.err)
c.Stop()
break out
}
pingChan = time.After(time.Minute)
case <-time.After(time.Minute):
log.Errorf("Timeout waiting for session RPC")
c.Stop()
break out
}
case c.currentBlock <- bs:
case <-c.quit:
break out
}
}
c.Stop()
close(c.dequeueNotification)
c.wg.Done()
}
// handler maintains a queue of notifications and the current state (best
// block) of the chain.
func (c *RPCClient) handlerVoting() {
var notifications []interface{}
enqueue := c.enqueueVotingNotification
var dequeue chan interface{}
var next interface{}
out:
for {
select {
case n, ok := <-enqueue:
if !ok {
// If no notifications are queued for handling,
// the queue is finished.
if len(notifications) == 0 {
break out
}
// nil channel so no more reads can occur.
enqueue = nil
continue
}
if len(notifications) == 0 {
next = n
dequeue = c.dequeueVotingNotification
}
notifications = append(notifications, n)
case dequeue <- next:
notifications[0] = nil
notifications = notifications[1:]
if len(notifications) != 0 {
next = notifications[0]
} else {
// If no more notifications can be enqueued, the
// queue is finished.
if enqueue == nil {
break out
}
dequeue = nil
}
case <-c.quit:
break out
}
}
close(c.dequeueVotingNotification)
c.wg.Done()
}
// POSTClient creates the equivalent HTTP POST dcrrpcclient.Client.
func (c *RPCClient) POSTClient() (*dcrrpcclient.Client, error) {
configCopy := *c.connConfig
configCopy.HTTPPostMode = true
return dcrrpcclient.New(&configCopy, nil)
}