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p2p, p2p/discover: track bootstrap state in p2p/discover

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This change simplifies the dial scheduling logic because it
no longer needs to track whether the discovery table has been
bootstrapped.
This commit is contained in:
Felix Lange 2015-12-07 12:06:49 +01:00
parent d1f507b7f1
commit 04c6369a09
6 changed files with 110 additions and 91 deletions
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33
p2p/dial.go
View File

@ -46,7 +46,6 @@ type dialstate struct {
ntab discoverTable
lookupRunning bool
bootstrapped bool
dialing map[discover.NodeID]connFlag
lookupBuf []*discover.Node // current discovery lookup results
@ -58,7 +57,6 @@ type dialstate struct {
type discoverTable interface {
Self() *discover.Node
Close()
Bootstrap([]*discover.Node)
Lookup(target discover.NodeID) []*discover.Node
ReadRandomNodes([]*discover.Node) int
}
@ -84,13 +82,9 @@ type dialTask struct {
// discoverTask runs discovery table operations.
// Only one discoverTask is active at any time.
//
// If bootstrap is true, the task runs Table.Bootstrap,
// otherwise it performs a random lookup and leaves the
// results in the task.
// discoverTask.Do performs a random lookup.
type discoverTask struct {
bootstrap bool
results []*discover.Node
results []*discover.Node
}
// A waitExpireTask is generated if there are no other tasks
@ -154,7 +148,7 @@ func (s *dialstate) newTasks(nRunning int, peers map[discover.NodeID]*Peer, now
// Use random nodes from the table for half of the necessary
// dynamic dials.
randomCandidates := needDynDials / 2
if randomCandidates > 0 && s.bootstrapped {
if randomCandidates > 0 {
n := s.ntab.ReadRandomNodes(s.randomNodes)
for i := 0; i < randomCandidates && i < n; i++ {
if addDial(dynDialedConn, s.randomNodes[i]) {
@ -171,12 +165,10 @@ func (s *dialstate) newTasks(nRunning int, peers map[discover.NodeID]*Peer, now
}
}
s.lookupBuf = s.lookupBuf[:copy(s.lookupBuf, s.lookupBuf[i:])]
// Launch a discovery lookup if more candidates are needed. The
// first discoverTask bootstraps the table and won't return any
// results.
// Launch a discovery lookup if more candidates are needed.
if len(s.lookupBuf) < needDynDials && !s.lookupRunning {
s.lookupRunning = true
newtasks = append(newtasks, &discoverTask{bootstrap: !s.bootstrapped})
newtasks = append(newtasks, &discoverTask{})
}
// Launch a timer to wait for the next node to expire if all
@ -196,9 +188,6 @@ func (s *dialstate) taskDone(t task, now time.Time) {
s.hist.add(t.dest.ID, now.Add(dialHistoryExpiration))
delete(s.dialing, t.dest.ID)
case *discoverTask:
if t.bootstrap {
s.bootstrapped = true
}
s.lookupRunning = false
s.lookupBuf = append(s.lookupBuf, t.results...)
}
@ -221,10 +210,6 @@ func (t *dialTask) String() string {
}
func (t *discoverTask) Do(srv *Server) {
if t.bootstrap {
srv.ntab.Bootstrap(srv.BootstrapNodes)
return
}
// newTasks generates a lookup task whenever dynamic dials are
// necessary. Lookups need to take some time, otherwise the
// event loop spins too fast.
@ -238,12 +223,8 @@ func (t *discoverTask) Do(srv *Server) {
t.results = srv.ntab.Lookup(target)
}
func (t *discoverTask) String() (s string) {
if t.bootstrap {
s = "discovery bootstrap"
} else {
s = "discovery lookup"
}
func (t *discoverTask) String() string {
s := "discovery lookup"
if len(t.results) > 0 {
s += fmt.Sprintf(" (%d results)", len(t.results))
}

28
p2p/dial_test.go
View File

@ -76,15 +76,10 @@ func runDialTest(t *testing.T, test dialtest) {
type fakeTable []*discover.Node
func (t fakeTable) Self() *discover.Node { return new(discover.Node) }
func (t fakeTable) Close() {}
func (t fakeTable) Bootstrap([]*discover.Node) {}
func (t fakeTable) Lookup(target discover.NodeID) []*discover.Node {
return nil
}
func (t fakeTable) ReadRandomNodes(buf []*discover.Node) int {
return copy(buf, t)
}
func (t fakeTable) Self() *discover.Node { return new(discover.Node) }
func (t fakeTable) Close() {}
func (t fakeTable) Lookup(discover.NodeID) []*discover.Node { return nil }
func (t fakeTable) ReadRandomNodes(buf []*discover.Node) int { return copy(buf, t) }
// This test checks that dynamic dials are launched from discovery results.
func TestDialStateDynDial(t *testing.T) {
@ -98,7 +93,7 @@ func TestDialStateDynDial(t *testing.T) {
{rw: &conn{flags: dynDialedConn, id: uintID(1)}},
{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
},
new: []task{&discoverTask{bootstrap: true}},
new: []task{&discoverTask{}},
},
// Dynamic dials are launched when it completes.
{
@ -108,7 +103,7 @@ func TestDialStateDynDial(t *testing.T) {
{rw: &conn{flags: dynDialedConn, id: uintID(2)}},
},
done: []task{
&discoverTask{bootstrap: true, results: []*discover.Node{
&discoverTask{results: []*discover.Node{
{ID: uintID(2)}, // this one is already connected and not dialed.
{ID: uintID(3)},
{ID: uintID(4)},
@ -238,22 +233,15 @@ func TestDialStateDynDialFromTable(t *testing.T) {
runDialTest(t, dialtest{
init: newDialState(nil, table, 10),
rounds: []round{
// Discovery bootstrap is launched.
{
new: []task{&discoverTask{bootstrap: true}},
},
// 5 out of 8 of the nodes returned by ReadRandomNodes are dialed.
{
done: []task{
&discoverTask{bootstrap: true},
},
new: []task{
&dialTask{dynDialedConn, &discover.Node{ID: uintID(1)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(2)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(3)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(4)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(5)}},
&discoverTask{bootstrap: false},
&discoverTask{},
},
},
// Dialing nodes 1,2 succeeds. Dials from the lookup are launched.
@ -275,7 +263,7 @@ func TestDialStateDynDialFromTable(t *testing.T) {
&dialTask{dynDialedConn, &discover.Node{ID: uintID(10)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(11)}},
&dialTask{dynDialedConn, &discover.Node{ID: uintID(12)}},
&discoverTask{bootstrap: false},
&discoverTask{},
},
},
// Dialing nodes 3,4,5 fails. The dials from the lookup succeed.

20
p2p/discover/node.go
View File

@ -80,6 +80,24 @@ func (n *Node) Incomplete() bool {
return n.IP == nil
}
// checks whether n is a valid complete node.
func (n *Node) validateComplete() error {
if n.Incomplete() {
return errors.New("incomplete node")
}
if n.UDP == 0 {
return errors.New("missing UDP port")
}
if n.TCP == 0 {
return errors.New("missing TCP port")
}
if n.IP.IsMulticast() || n.IP.IsUnspecified() {
return errors.New("invalid IP (multicast/unspecified)")
}
_, err := n.ID.Pubkey() // validate the key (on curve, etc.)
return err
}
// The string representation of a Node is a URL.
// Please see ParseNode for a description of the format.
func (n *Node) String() string {
@ -249,7 +267,7 @@ func (id NodeID) Pubkey() (*ecdsa.PublicKey, error) {
p.X.SetBytes(id[:half])
p.Y.SetBytes(id[half:])
if !p.Curve.IsOnCurve(p.X, p.Y) {
return nil, errors.New("not a point on the S256 curve")
return nil, errors.New("id is invalid secp256k1 curve point")
}
return p, nil
}

105
p2p/discover/table.go
View File

@ -25,6 +25,7 @@ package discover
import (
"crypto/rand"
"encoding/binary"
"fmt"
"net"
"sort"
"sync"
@ -56,7 +57,7 @@ type Table struct {
nursery []*Node // bootstrap nodes
db *nodeDB // database of known nodes
refreshReq chan struct{}
refreshReq chan chan struct{}
closeReq chan struct{}
closed chan struct{}
@ -102,7 +103,7 @@ func newTable(t transport, ourID NodeID, ourAddr *net.UDPAddr, nodeDBPath string
self: NewNode(ourID, ourAddr.IP, uint16(ourAddr.Port), uint16(ourAddr.Port)),
bonding: make(map[NodeID]*bondproc),
bondslots: make(chan struct{}, maxBondingPingPongs),
refreshReq: make(chan struct{}),
refreshReq: make(chan chan struct{}),
closeReq: make(chan struct{}),
closed: make(chan struct{}),
}
@ -179,21 +180,27 @@ func (tab *Table) Close() {
}
}
// Bootstrap sets the bootstrap nodes. These nodes are used to connect
// to the network if the table is empty. Bootstrap will also attempt to
// fill the table by performing random lookup operations on the
// network.
func (tab *Table) Bootstrap(nodes []*Node) {
// SetFallbackNodes sets the initial points of contact. These nodes
// are used to connect to the network if the table is empty and there
// are no known nodes in the database.
func (tab *Table) SetFallbackNodes(nodes []*Node) error {
for _, n := range nodes {
if err := n.validateComplete(); err != nil {
return fmt.Errorf("bad bootstrap/fallback node %q (%v)", n, err)
}
}
tab.mutex.Lock()
// TODO: maybe filter nodes with bad fields (nil, etc.) to avoid strange crashes
tab.nursery = make([]*Node, 0, len(nodes))
for _, n := range nodes {
cpy := *n
// Recompute cpy.sha because the node might not have been
// created by NewNode or ParseNode.
cpy.sha = crypto.Sha3Hash(n.ID[:])
tab.nursery = append(tab.nursery, &cpy)
}
tab.mutex.Unlock()
tab.requestRefresh()
tab.refresh()
return nil
}
// Resolve searches for a specific node with the given ID.
@ -224,26 +231,36 @@ func (tab *Table) Resolve(targetID NodeID) *Node {
// The given target does not need to be an actual node
// identifier.
func (tab *Table) Lookup(targetID NodeID) []*Node {
return tab.lookup(targetID, true)
}
func (tab *Table) lookup(targetID NodeID, refreshIfEmpty bool) []*Node {
var (
target = crypto.Sha3Hash(targetID[:])
asked = make(map[NodeID]bool)
seen = make(map[NodeID]bool)
reply = make(chan []*Node, alpha)
pendingQueries = 0
result *nodesByDistance
)
// don't query further if we hit ourself.
// unlikely to happen often in practice.
asked[tab.self.ID] = true
tab.mutex.Lock()
// generate initial result set
result := tab.closest(target, bucketSize)
tab.mutex.Unlock()
// If the result set is empty, all nodes were dropped, refresh.
if len(result.entries) == 0 {
tab.requestRefresh()
return nil
for {
tab.mutex.Lock()
// generate initial result set
result = tab.closest(target, bucketSize)
tab.mutex.Unlock()
if len(result.entries) > 0 || !refreshIfEmpty {
break
}
// The result set is empty, all nodes were dropped, refresh.
// We actually wait for the refresh to complete here. The very
// first query will hit this case and run the bootstrapping
// logic.
<-tab.refresh()
refreshIfEmpty = false
}
for {
@ -287,24 +304,24 @@ func (tab *Table) Lookup(targetID NodeID) []*Node {
return result.entries
}
func (tab *Table) requestRefresh() {
func (tab *Table) refresh() <-chan struct{} {
done := make(chan struct{})
select {
case tab.refreshReq <- struct{}{}:
case tab.refreshReq <- done:
case <-tab.closed:
close(done)
}
return done
}
// refreshLoop schedules doRefresh runs and coordinates shutdown.
func (tab *Table) refreshLoop() {
defer func() {
tab.db.close()
if tab.net != nil {
tab.net.close()
}
close(tab.closed)
}()
timer := time.NewTicker(autoRefreshInterval)
var done chan struct{}
var (
timer = time.NewTicker(autoRefreshInterval)
waiting []chan struct{} // accumulates waiting callers while doRefresh runs
done chan struct{} // where doRefresh reports completion
)
loop:
for {
select {
case <-timer.C:
@ -312,20 +329,34 @@ func (tab *Table) refreshLoop() {
done = make(chan struct{})
go tab.doRefresh(done)
}
case <-tab.refreshReq:
case req := <-tab.refreshReq:
waiting = append(waiting, req)
if done == nil {
done = make(chan struct{})
go tab.doRefresh(done)
}
case <-done:
for _, ch := range waiting {
close(ch)
}
waiting = nil
done = nil
case <-tab.closeReq:
if done != nil {
<-done
}
return
break loop
}
}
if tab.net != nil {
tab.net.close()
}
if done != nil {
<-done
}
for _, ch := range waiting {
close(ch)
}
tab.db.close()
close(tab.closed)
}
// doRefresh performs a lookup for a random target to keep buckets
@ -342,7 +373,7 @@ func (tab *Table) doRefresh(done chan struct{}) {
// We perform a lookup with a random target instead.
var target NodeID
rand.Read(target[:])
result := tab.Lookup(target)
result := tab.lookup(target, false)
if len(result) > 0 {
return
}
@ -366,7 +397,7 @@ func (tab *Table) doRefresh(done chan struct{}) {
tab.mutex.Unlock()
// Finally, do a self lookup to fill up the buckets.
tab.Lookup(tab.self.ID)
tab.lookup(tab.self.ID, false)
}
// closest returns the n nodes in the table that are closest to the

12
p2p/discover/udp.go
View File

@ -114,13 +114,11 @@ func makeEndpoint(addr *net.UDPAddr, tcpPort uint16) rpcEndpoint {
return rpcEndpoint{IP: ip, UDP: uint16(addr.Port), TCP: tcpPort}
}
func nodeFromRPC(rn rpcNode) (n *Node, valid bool) {
func nodeFromRPC(rn rpcNode) (*Node, error) {
// TODO: don't accept localhost, LAN addresses from internet hosts
// TODO: check public key is on secp256k1 curve
if rn.IP.IsMulticast() || rn.IP.IsUnspecified() || rn.UDP == 0 {
return nil, false
}
return NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP), true
n := NewNode(rn.ID, rn.IP, rn.UDP, rn.TCP)
err := n.validateComplete()
return n, err
}
func nodeToRPC(n *Node) rpcNode {
@ -271,7 +269,7 @@ func (t *udp) findnode(toid NodeID, toaddr *net.UDPAddr, target NodeID) ([]*Node
reply := r.(*neighbors)
for _, rn := range reply.Nodes {
nreceived++
if n, valid := nodeFromRPC(rn); valid {
if n, err := nodeFromRPC(rn); err == nil {
nodes = append(nodes, n)
}
}

3
p2p/server.go
View File

@ -334,6 +334,9 @@ func (srv *Server) Start() (err error) {
if err != nil {
return err
}
if err := ntab.SetFallbackNodes(srv.BootstrapNodes); err != nil {
return err
}
srv.ntab = ntab
}