forked from hyperledger/fabric-sdk-go
/
dispatcher.go
executable file
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/
dispatcher.go
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/*
Copyright SecureKey Technologies Inc. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package dispatcher
import (
"fmt"
"sync"
"time"
"github.com/hyperledger/fabric-sdk-go/pkg/common/logging"
"github.com/hyperledger/fabric-sdk-go/pkg/common/options"
"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/context"
"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/fab"
"github.com/hyperledger/fabric-sdk-go/pkg/fab/events/api"
"github.com/hyperledger/fabric-sdk-go/pkg/fab/events/client/peerresolver"
esdispatcher "github.com/hyperledger/fabric-sdk-go/pkg/fab/events/service/dispatcher"
"github.com/pkg/errors"
)
var logger = logging.NewLogger("fabsdk/fab")
// Dispatcher is responsible for handling all events, including connection and registration events originating from the client,
// and events originating from the event server. All events are processed in a single Go routine
// in order to avoid any race conditions and to ensure that events are processed in the order that they are received.
// This avoids the need for synchronization.
type Dispatcher struct {
*esdispatcher.Dispatcher
params
context context.Client
chConfig fab.ChannelCfg
connection api.Connection
connectionRegistration *ConnectionReg
connectionProvider api.ConnectionProvider
discoveryService fab.DiscoveryService
peerResolver peerresolver.Resolver
peerMonitorDone chan struct{}
peer fab.Peer
lock sync.RWMutex
}
// New creates a new dispatcher
func New(context context.Client, chConfig fab.ChannelCfg, discoveryService fab.DiscoveryService, connectionProvider api.ConnectionProvider, opts ...options.Opt) *Dispatcher {
params := defaultParams(context, chConfig.ID())
options.Apply(params, opts)
dispatcher := &Dispatcher{
Dispatcher: esdispatcher.New(opts...),
params: *params,
context: context,
chConfig: chConfig,
discoveryService: discoveryService,
connectionProvider: connectionProvider,
}
dispatcher.peerResolver = params.peerResolverProvider(dispatcher, context, chConfig.ID(), opts...)
return dispatcher
}
// Start starts the dispatcher
func (ed *Dispatcher) Start() error {
ed.registerHandlers()
if err := ed.Dispatcher.Start(); err != nil {
return errors.WithMessage(err, "error starting client event dispatcher")
}
return nil
}
// ChannelConfig returns the channel configuration
func (ed *Dispatcher) ChannelConfig() fab.ChannelCfg {
return ed.chConfig
}
// Connection returns the connection to the event server
func (ed *Dispatcher) Connection() api.Connection {
return ed.connection
}
// HandleStopEvent handles a Stop event by clearing all registrations
// and stopping the listener
func (ed *Dispatcher) HandleStopEvent(e esdispatcher.Event) {
// Remove all registrations and close the associated event channels
// so that the client is notified that the registration has been removed
ed.clearConnectionRegistration()
if ed.peerMonitorDone != nil {
close(ed.peerMonitorDone)
ed.peerMonitorDone = nil
}
ed.Dispatcher.HandleStopEvent(e)
}
// HandleConnectEvent initiates a connection to the event server
func (ed *Dispatcher) HandleConnectEvent(e esdispatcher.Event) {
evt := e.(*ConnectEvent)
if ed.connection != nil {
// Already connected. No error.
evt.ErrCh <- nil
return
}
eventch, err := ed.EventCh()
if err != nil {
evt.ErrCh <- err
return
}
peers, err := ed.discoveryService.GetPeers()
if err != nil {
evt.ErrCh <- err
return
}
if len(peers) == 0 {
evt.ErrCh <- errors.New("no peers to connect to")
return
}
peer, err := ed.peerResolver.Resolve(peers)
if err != nil {
evt.ErrCh <- err
return
}
conn, err := ed.connectionProvider(ed.context, ed.chConfig, peer)
if err != nil {
logger.Warnf("error creating connection: %s", err)
evt.ErrCh <- errors.WithMessage(err, fmt.Sprintf("could not create client conn"))
return
}
ed.connection = conn
ed.setConnectedPeer(peer)
go ed.connection.Receive(eventch)
evt.ErrCh <- nil
}
// HandleDisconnectEvent disconnects from the event server
func (ed *Dispatcher) HandleDisconnectEvent(e esdispatcher.Event) {
evt := e.(*DisconnectEvent)
if ed.connection == nil {
evt.Errch <- errors.New("connection already closed")
return
}
logger.Debug("Closing connection due to disconnect event...")
ed.connection.Close()
ed.connection = nil
ed.setConnectedPeer(nil)
evt.Errch <- nil
}
// HandleRegisterConnectionEvent registers a connection listener
func (ed *Dispatcher) HandleRegisterConnectionEvent(e esdispatcher.Event) {
evt := e.(*RegisterConnectionEvent)
if ed.connectionRegistration != nil {
evt.ErrCh <- errors.New("registration already exists for connection event")
return
}
ed.connectionRegistration = evt.Reg
evt.RegCh <- evt.Reg
}
// HandleConnectedEvent sends a 'connected' event to any registered listener
func (ed *Dispatcher) HandleConnectedEvent(e esdispatcher.Event) {
evt := e.(*ConnectedEvent)
logger.Debugf("Handling connected event: %+v", evt)
if ed.connectionRegistration != nil && ed.connectionRegistration.Eventch != nil {
select {
case ed.connectionRegistration.Eventch <- NewConnectionEvent(true, nil):
default:
logger.Warn("Unable to send to connection event channel.")
}
}
if ed.peerMonitorPeriod > 0 {
ed.peerMonitorDone = make(chan struct{})
go ed.monitorPeer(ed.peerMonitorDone)
}
}
// HandleDisconnectedEvent sends a 'disconnected' event to any registered listener
func (ed *Dispatcher) HandleDisconnectedEvent(e esdispatcher.Event) {
evt := e.(*DisconnectedEvent)
logger.Debugf("Disconnecting from event server: %s", evt.Err)
if ed.connection != nil {
ed.connection.Close()
ed.connection = nil
}
if ed.connectionRegistration != nil {
logger.Debugf("Disconnected from event server: %s", evt.Err)
select {
case ed.connectionRegistration.Eventch <- NewConnectionEvent(false, evt.Err):
default:
logger.Warn("Unable to send to connection event channel.")
}
} else {
logger.Warnf("Disconnected from event server: %s", evt.Err)
}
if ed.peerMonitorDone != nil {
close(ed.peerMonitorDone)
ed.peerMonitorDone = nil
}
}
func (ed *Dispatcher) registerHandlers() {
// Override existing handlers
ed.RegisterHandler(&esdispatcher.StopEvent{}, ed.HandleStopEvent)
// Register new handlers
ed.RegisterHandler(&ConnectEvent{}, ed.HandleConnectEvent)
ed.RegisterHandler(&DisconnectEvent{}, ed.HandleDisconnectEvent)
ed.RegisterHandler(&ConnectedEvent{}, ed.HandleConnectedEvent)
ed.RegisterHandler(&DisconnectedEvent{}, ed.HandleDisconnectedEvent)
ed.RegisterHandler(&RegisterConnectionEvent{}, ed.HandleRegisterConnectionEvent)
}
func (ed *Dispatcher) clearConnectionRegistration() {
if ed.connectionRegistration != nil {
logger.Debug("Closing connection registration event channel.")
close(ed.connectionRegistration.Eventch)
ed.connectionRegistration = nil
}
}
func (ed *Dispatcher) monitorPeer(done chan struct{}) {
logger.Debugf("Starting peer monitor on channel [%s]", ed.chConfig.ID())
ticker := time.NewTicker(ed.peerMonitorPeriod)
defer ticker.Stop()
for {
select {
case <-ticker.C:
if ed.disconnected() {
// Disconnected
logger.Debugf("Client on channel [%s] has disconnected - stopping disconnect monitor", ed.chConfig.ID())
return
}
case <-done:
logger.Debugf("Stopping block height monitor on channel [%s]", ed.chConfig.ID())
return
}
}
}
// disconnected checks if the currently connected peer should be disconnected
// Returns true if the client has been disconnected; false otherwise
func (ed *Dispatcher) disconnected() bool {
connectedPeer := ed.ConnectedPeer()
if connectedPeer == nil {
logger.Debugf("Not connected yet")
return false
}
logger.Debugf("Checking if event client should disconnect from peer [%s] on channel [%s]...", connectedPeer.URL(), ed.chConfig.ID())
peers, err := ed.discoveryService.GetPeers()
if err != nil {
logger.Warnf("Error calling peer resolver: %s", err)
return false
}
if !ed.peerResolver.ShouldDisconnect(peers, connectedPeer) {
logger.Debugf("Event client will not disconnect from peer [%s] on channel [%s]...", connectedPeer.URL(), ed.chConfig.ID())
return false
}
logger.Warnf("The peer resolver determined that the event client should be disconnected from connected peer [%s] on channel [%s]. Disconnecting ...", connectedPeer.URL(), ed.chConfig.ID())
if err := ed.disconnect(); err != nil {
logger.Warnf("Error disconnecting event client from peer [%s] on channel [%s]: %s", connectedPeer.URL(), ed.chConfig.ID(), err)
return false
}
logger.Warnf("Successfully disconnected event client from peer [%s] on channel [%s]", connectedPeer.URL(), ed.chConfig.ID())
return true
}
func (ed *Dispatcher) disconnect() error {
eventch, err := ed.EventCh()
if err != nil {
return errors.WithMessage(err, "unable to get event dispatcher channel")
}
errch := make(chan error)
eventch <- NewDisconnectEvent(errch)
err = <-errch
if err != nil {
return err
}
// Send a DisconnectedEvent. This will trigger a reconnect.
eventch <- NewDisconnectedEvent(nil)
return nil
}
func (ed *Dispatcher) setConnectedPeer(peer fab.Peer) {
ed.lock.Lock()
defer ed.lock.Unlock()
ed.peer = peer
}
// ConnectedPeer returns the connected peer
func (ed *Dispatcher) ConnectedPeer() fab.Peer {
ed.lock.RLock()
defer ed.lock.RUnlock()
return ed.peer
}