You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
312 lines
8.3 KiB
312 lines
8.3 KiB
package statesync
|
|
|
|
import (
|
|
"context"
|
|
"errors"
|
|
"fmt"
|
|
"sync"
|
|
|
|
"github.com/tendermint/tendermint/internal/p2p"
|
|
"github.com/tendermint/tendermint/light/provider"
|
|
ssproto "github.com/tendermint/tendermint/proto/tendermint/statesync"
|
|
tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
|
|
"github.com/tendermint/tendermint/types"
|
|
)
|
|
|
|
var (
|
|
errNoConnectedPeers = errors.New("no available peers to dispatch request to")
|
|
errUnsolicitedResponse = errors.New("unsolicited light block response")
|
|
errPeerAlreadyBusy = errors.New("peer is already processing a request")
|
|
errDisconnected = errors.New("dispatcher disconnected")
|
|
)
|
|
|
|
// A Dispatcher multiplexes concurrent requests by multiple peers for light blocks.
|
|
// Only one request per peer can be sent at a time. Subsequent concurrent requests will
|
|
// report an error from the LightBlock method.
|
|
// NOTE: It is not the responsibility of the dispatcher to verify the light blocks.
|
|
type Dispatcher struct {
|
|
// the channel with which to send light block requests on
|
|
requestCh chan<- p2p.Envelope
|
|
closeCh chan struct{}
|
|
|
|
mtx sync.Mutex
|
|
// all pending calls that have been dispatched and are awaiting an answer
|
|
calls map[types.NodeID]chan *types.LightBlock
|
|
}
|
|
|
|
func NewDispatcher(requestCh chan<- p2p.Envelope) *Dispatcher {
|
|
return &Dispatcher{
|
|
requestCh: requestCh,
|
|
closeCh: make(chan struct{}),
|
|
calls: make(map[types.NodeID]chan *types.LightBlock),
|
|
}
|
|
}
|
|
|
|
// LightBlock uses the request channel to fetch a light block from a given peer
|
|
// tracking, the call and waiting for the reactor to pass back the response. A nil
|
|
// LightBlock response is used to signal that the peer doesn't have the requested LightBlock.
|
|
func (d *Dispatcher) LightBlock(ctx context.Context, height int64, peer types.NodeID) (*types.LightBlock, error) {
|
|
// dispatch the request to the peer
|
|
callCh, err := d.dispatch(peer, height)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// clean up the call after a response is returned
|
|
defer func() {
|
|
d.mtx.Lock()
|
|
defer d.mtx.Unlock()
|
|
if call, ok := d.calls[peer]; ok {
|
|
delete(d.calls, peer)
|
|
close(call)
|
|
}
|
|
}()
|
|
|
|
// wait for a response, cancel or timeout
|
|
select {
|
|
case resp := <-callCh:
|
|
return resp, nil
|
|
|
|
case <-ctx.Done():
|
|
return nil, ctx.Err()
|
|
|
|
case <-d.closeCh:
|
|
return nil, errDisconnected
|
|
}
|
|
}
|
|
|
|
// dispatch takes a peer and allocates it a channel so long as it's not already
|
|
// busy and the receiving channel is still running. It then dispatches the message
|
|
func (d *Dispatcher) dispatch(peer types.NodeID, height int64) (chan *types.LightBlock, error) {
|
|
d.mtx.Lock()
|
|
defer d.mtx.Unlock()
|
|
select {
|
|
case <-d.closeCh:
|
|
return nil, errDisconnected
|
|
default:
|
|
}
|
|
|
|
ch := make(chan *types.LightBlock, 1)
|
|
|
|
// check if a request for the same peer has already been made
|
|
if _, ok := d.calls[peer]; ok {
|
|
close(ch)
|
|
return ch, errPeerAlreadyBusy
|
|
}
|
|
d.calls[peer] = ch
|
|
|
|
// send request
|
|
d.requestCh <- p2p.Envelope{
|
|
To: peer,
|
|
Message: &ssproto.LightBlockRequest{
|
|
Height: uint64(height),
|
|
},
|
|
}
|
|
|
|
return ch, nil
|
|
}
|
|
|
|
// Respond allows the underlying process which receives requests on the
|
|
// requestCh to respond with the respective light block. A nil response is used to
|
|
// represent that the receiver of the request does not have a light block at that height.
|
|
func (d *Dispatcher) Respond(lb *tmproto.LightBlock, peer types.NodeID) error {
|
|
d.mtx.Lock()
|
|
defer d.mtx.Unlock()
|
|
|
|
// check that the response came from a request
|
|
answerCh, ok := d.calls[peer]
|
|
if !ok {
|
|
// this can also happen if the response came in after the timeout
|
|
return errUnsolicitedResponse
|
|
}
|
|
|
|
// If lb is nil we take that to mean that the peer didn't have the requested light
|
|
// block and thus pass on the nil to the caller.
|
|
if lb == nil {
|
|
answerCh <- nil
|
|
return nil
|
|
}
|
|
|
|
block, err := types.LightBlockFromProto(lb)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
answerCh <- block
|
|
return nil
|
|
}
|
|
|
|
// Close shuts down the dispatcher and cancels any pending calls awaiting responses.
|
|
// Peers awaiting responses that have not arrived are delivered a nil block.
|
|
func (d *Dispatcher) Close() {
|
|
d.mtx.Lock()
|
|
defer d.mtx.Unlock()
|
|
close(d.closeCh)
|
|
for peer, call := range d.calls {
|
|
delete(d.calls, peer)
|
|
close(call)
|
|
}
|
|
}
|
|
|
|
func (d *Dispatcher) Done() <-chan struct{} {
|
|
return d.closeCh
|
|
}
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
// BlockProvider is a p2p based light provider which uses a dispatcher connected
|
|
// to the state sync reactor to serve light blocks to the light client
|
|
//
|
|
// TODO: This should probably be moved over to the light package but as we're
|
|
// not yet officially supporting p2p light clients we'll leave this here for now.
|
|
//
|
|
// NOTE: BlockProvider will return an error with concurrent calls. However, we don't
|
|
// need a mutex because a light client (and the backfill process) will never call a
|
|
// method more than once at the same time
|
|
type BlockProvider struct {
|
|
peer types.NodeID
|
|
chainID string
|
|
dispatcher *Dispatcher
|
|
}
|
|
|
|
// Creates a block provider which implements the light client Provider interface.
|
|
func NewBlockProvider(peer types.NodeID, chainID string, dispatcher *Dispatcher) *BlockProvider {
|
|
return &BlockProvider{
|
|
peer: peer,
|
|
chainID: chainID,
|
|
dispatcher: dispatcher,
|
|
}
|
|
}
|
|
|
|
// LightBlock fetches a light block from the peer at a specified height returning either a
|
|
// light block or an appropriate error.
|
|
func (p *BlockProvider) LightBlock(ctx context.Context, height int64) (*types.LightBlock, error) {
|
|
lb, err := p.dispatcher.LightBlock(ctx, height, p.peer)
|
|
switch err {
|
|
case nil:
|
|
if lb == nil {
|
|
return nil, provider.ErrLightBlockNotFound
|
|
}
|
|
case context.DeadlineExceeded, context.Canceled:
|
|
return nil, err
|
|
case errPeerAlreadyBusy:
|
|
return nil, provider.ErrLightBlockNotFound
|
|
default:
|
|
return nil, provider.ErrUnreliableProvider{Reason: err.Error()}
|
|
}
|
|
|
|
// check that the height requested is the same one returned
|
|
if lb.Height != height {
|
|
return nil, provider.ErrBadLightBlock{
|
|
Reason: fmt.Errorf("expected height %d, got height %d", height, lb.Height),
|
|
}
|
|
}
|
|
|
|
// perform basic validation
|
|
if err := lb.ValidateBasic(p.chainID); err != nil {
|
|
return nil, provider.ErrBadLightBlock{Reason: err}
|
|
}
|
|
|
|
return lb, nil
|
|
}
|
|
|
|
// ReportEvidence should allow for the light client to report any light client
|
|
// attacks. This is a no op as there currently isn't a way to wire this up to
|
|
// the evidence reactor (we should endeavor to do this in the future but for now
|
|
// it's not critical for backwards verification)
|
|
func (p *BlockProvider) ReportEvidence(ctx context.Context, ev types.Evidence) error {
|
|
return nil
|
|
}
|
|
|
|
// String implements stringer interface
|
|
func (p *BlockProvider) String() string { return string(p.peer) }
|
|
|
|
//----------------------------------------------------------------
|
|
|
|
// peerList is a rolling list of peers. This is used to distribute the load of
|
|
// retrieving blocks over all the peers the reactor is connected to
|
|
type peerList struct {
|
|
mtx sync.Mutex
|
|
peers []types.NodeID
|
|
waiting []chan types.NodeID
|
|
}
|
|
|
|
func newPeerList() *peerList {
|
|
return &peerList{
|
|
peers: make([]types.NodeID, 0),
|
|
waiting: make([]chan types.NodeID, 0),
|
|
}
|
|
}
|
|
|
|
func (l *peerList) Len() int {
|
|
l.mtx.Lock()
|
|
defer l.mtx.Unlock()
|
|
return len(l.peers)
|
|
}
|
|
|
|
func (l *peerList) Pop(ctx context.Context) types.NodeID {
|
|
l.mtx.Lock()
|
|
if len(l.peers) == 0 {
|
|
// if we don't have any peers in the list we block until a peer is
|
|
// appended
|
|
wait := make(chan types.NodeID, 1)
|
|
l.waiting = append(l.waiting, wait)
|
|
// unlock whilst waiting so that the list can be appended to
|
|
l.mtx.Unlock()
|
|
select {
|
|
case peer := <-wait:
|
|
return peer
|
|
|
|
case <-ctx.Done():
|
|
return ""
|
|
}
|
|
}
|
|
|
|
peer := l.peers[0]
|
|
l.peers = l.peers[1:]
|
|
l.mtx.Unlock()
|
|
return peer
|
|
}
|
|
|
|
func (l *peerList) Append(peer types.NodeID) {
|
|
l.mtx.Lock()
|
|
defer l.mtx.Unlock()
|
|
if len(l.waiting) > 0 {
|
|
wait := l.waiting[0]
|
|
l.waiting = l.waiting[1:]
|
|
wait <- peer
|
|
close(wait)
|
|
} else {
|
|
l.peers = append(l.peers, peer)
|
|
}
|
|
}
|
|
|
|
func (l *peerList) Remove(peer types.NodeID) {
|
|
l.mtx.Lock()
|
|
defer l.mtx.Unlock()
|
|
for i, p := range l.peers {
|
|
if p == peer {
|
|
l.peers = append(l.peers[:i], l.peers[i+1:]...)
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func (l *peerList) All() []types.NodeID {
|
|
l.mtx.Lock()
|
|
defer l.mtx.Unlock()
|
|
return l.peers
|
|
}
|
|
|
|
func (l *peerList) Contains(id types.NodeID) bool {
|
|
l.mtx.Lock()
|
|
defer l.mtx.Unlock()
|
|
|
|
for _, p := range l.peers {
|
|
if id == p {
|
|
return true
|
|
}
|
|
}
|
|
|
|
return false
|
|
}
|