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broker.go
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broker.go
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// Copyright (C) 2023 Gobalsky Labs Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package broker
import (
"context"
"fmt"
"sync"
"time"
"code.vegaprotocol.io/vega/core/events"
"code.vegaprotocol.io/vega/libs/broker"
"code.vegaprotocol.io/vega/logging"
)
type Stats interface {
IncrementEventCount(count uint64)
}
// Interface interface (horribly named) is declared here to provide a drop-in replacement for broker mocks used throughout
// in addition to providing the classical mockgen functionality, this mock can be used to check the actual events that will be generated
// so we don't have to rely on test-only helper functions
//
//go:generate go run github.com/golang/mock/mockgen -destination mocks/broker_mock.go -package mocks code.vegaprotocol.io/vega/core/broker Interface
type Interface interface {
Stage(event events.Event)
Send(event events.Event)
SendBatch(events []events.Event)
Subscribe(s broker.Subscriber) int
SubscribeBatch(subs ...broker.Subscriber)
Unsubscribe(k int)
SetStreaming(on bool) bool
}
// SocketClient is an interface to send serialized events over a socket.
//
//go:generate go run github.com/golang/mock/mockgen -destination mocks/socket_client_mock.go -package mocks code.vegaprotocol.io/vega/core/broker SocketClient
type SocketClient interface {
SendBatch(events []events.Event) error
Receive(ctx context.Context) (<-chan events.Event, <-chan error)
}
type FileClientSend interface {
SendBatch(events []events.Event) error
}
type subscription struct {
broker.Subscriber
required bool
}
// Broker - the base broker type
// perhaps we can extend this to embed into type-specific brokers.
type Broker struct {
ctx context.Context
mu sync.Mutex
tSubs map[events.Type]map[int]*subscription
// these fields ensure a unique ID for all subscribers, regardless of what event types they subscribe to
// once the broker context is cancelled, this map will be used to notify all subscribers, who can then
// close their internal channels. We can then cleanly shut down (not having unclosed channels)
subs map[int]subscription
keys []int
eChans map[events.Type]chan []events.Event
seqGen *gen
log *logging.Logger
config Config
socketClient SocketClient
fileClient FileClientSend
canStream bool // whether not we should send events to the socketClient
stats Stats
staged []events.Event
}
// New creates a new base broker.
func New(ctx context.Context, log *logging.Logger, config Config, stats Stats) (*Broker, error) {
log = log.Named(namedLogger)
log.SetLevel(config.Level.Get())
b := &Broker{
ctx: ctx,
log: log,
tSubs: map[events.Type]map[int]*subscription{},
subs: map[int]subscription{},
keys: []int{},
eChans: map[events.Type]chan []events.Event{},
seqGen: newGen(),
config: config,
canStream: bool(config.Socket.Enabled),
stats: stats,
staged: []events.Event{},
}
if config.Socket.Enabled {
sc, err := newSocketClient(ctx, log, &config.Socket)
if err != nil {
return nil, fmt.Errorf("failed to initialize socket client: %w", err)
}
b.socketClient = sc
}
if config.File.Enabled {
fc, err := NewFileClient(log, &config.File)
if err != nil {
return nil, fmt.Errorf("failed to initialize file client: %w", err)
}
b.fileClient = fc
}
return b, nil
}
func (b *Broker) OnTick(ctx context.Context, _ time.Time) {
if len(b.staged) == 0 {
return
}
for _, evt := range b.staged {
evt.Replace(ctx)
b.Send(evt)
}
b.staged = []events.Event{}
}
func (b *Broker) sendChannel(sub broker.Subscriber, evts []events.Event) {
// wait for a max of 1 second
timeout := time.NewTimer(time.Second)
defer func() {
// drain the channel if we managed to leave the function before the timer expired
if !timeout.Stop() {
<-timeout.C
}
}()
select {
case <-b.ctx.Done():
return
case <-sub.Closed():
return
case sub.C() <- evts:
return
case <-timeout.C:
return
}
}
func (b *Broker) sendChannelSync(sub broker.Subscriber, evts []events.Event) bool {
select {
case <-b.ctx.Done():
return false
case <-sub.Skip():
return false
case <-sub.Closed():
return true
case sub.C() <- evts:
return false
default:
// @TODO perhaps log that we've encountered the channel buffer of a subscriber
// this could help us find out what combination of event types + batch sizes are
// problematic
go b.sendChannel(sub, evts)
return false
}
}
func (b *Broker) startSending(t events.Type, evts []events.Event) {
if b.StreamingEnabled() {
if err := b.socketClient.SendBatch(evts); err != nil {
b.log.Fatal("Failed to send to socket client", logging.Error(err))
}
}
if b.fileStreamEnabled() {
if err := b.fileClient.SendBatch(evts); err != nil {
b.log.Fatal("Failed to send to file client", logging.Error(err))
}
}
b.mu.Lock()
ch, ok := b.eChans[t]
if !ok {
subs := b.getSubsByType(t)
ln := len(subs) + 1 // at least buffer 1
ch = make(chan []events.Event, ln*20+20) // create a channel with buffer, min 40
b.eChans[t] = ch // assign the newly created channel
}
b.mu.Unlock()
select {
case <-b.ctx.Done():
return
default:
ch <- evts
}
if ok {
// we already started the routine to consume the channel
// we can return here
return
}
go func(ch chan []events.Event, t events.Type) {
defer func() {
b.mu.Lock()
delete(b.eChans, t)
close(ch)
b.mu.Unlock()
}()
for {
select {
case <-b.ctx.Done():
return
case evts := <-ch:
b.mu.Lock()
subs := b.getSubsByType(t)
b.mu.Unlock()
unsub := make([]int, 0, len(subs))
for k, sub := range subs {
select {
case <-b.ctx.Done():
return
case <-sub.Skip():
continue
case <-sub.Closed():
unsub = append(unsub, k)
default:
if sub.required {
sub.Push(evts...)
} else if shouldUnsubscribe := b.sendChannelSync(sub, evts); shouldUnsubscribe {
unsub = append(unsub, k)
}
}
}
if len(unsub) != 0 {
b.mu.Lock()
b.rmSubs(unsub...)
b.mu.Unlock()
}
}
}
}(ch, t)
}
// SendBatch sends a slice of events to subscribers that can handle the events in the slice
// the events don't have to be of the same type, and most subscribers will ignore unknown events
// but this will slow down those subscribers, so avoid doing silly things.
func (b *Broker) SendBatch(events []events.Event) {
if len(events) == 0 {
return
}
b.stats.IncrementEventCount(uint64(len(events)))
evts := b.seqGen.setSequence(events...)
b.startSending(events[0].Type(), evts)
}
// Send sends an event to all subscribers.
func (b *Broker) Send(event events.Event) {
b.stats.IncrementEventCount(1)
b.startSending(event.Type(), b.seqGen.setSequence(event))
}
// Stages an event to be sent at the start of the next block.
func (b *Broker) Stage(event events.Event) {
b.staged = append(b.staged, event)
}
// simplified version for better performance - unfortunately, we'll still need to copy the map.
func (b *Broker) getSubsByType(t events.Type) map[int]*subscription {
// we add the entire ALL map to type-specific maps, so if set, we can return this map directly
subs, ok := b.tSubs[t]
if !ok {
// if a typed map isn't set (yet), and it's not the error event, we can return
// ALL subscribers directly instead
subs = b.tSubs[events.All]
}
// we still need to create a copy to keep the race detector happy
cpy := make(map[int]*subscription, len(subs))
for k, v := range subs {
cpy[k] = v
}
return cpy
}
// Subscribe registers a new subscriber, returning the key.
func (b *Broker) Subscribe(s broker.Subscriber) int {
b.mu.Lock()
k := b.subscribe(s)
s.SetID(k)
b.mu.Unlock()
return k
}
func (b *Broker) SubscribeBatch(subs ...broker.Subscriber) {
b.mu.Lock()
for _, s := range subs {
k := b.subscribe(s)
s.SetID(k)
}
b.mu.Unlock()
}
func (b *Broker) subscribe(s broker.Subscriber) int {
k := b.getKey()
sub := subscription{
Subscriber: s,
required: s.Ack(),
}
b.subs[k] = sub
types := sub.Types()
// filter out weird types values like []events.Type{events.PartyEvent, events.All,}
// those subscribers subscribe to all events no matter what, so treat them accordingly
isAll := false
if len(types) == 0 {
isAll = true
types = []events.Type{events.All}
} else {
for _, t := range types {
if t == events.All {
types = []events.Type{events.All}
isAll = true
break
}
}
}
for _, t := range types {
if _, ok := b.tSubs[t]; !ok {
b.tSubs[t] = map[int]*subscription{}
if !isAll {
// not the ALL event, so can be added to the map, and as the "all" subscribers should be
for ak, as := range b.tSubs[events.All] {
b.tSubs[t][ak] = as
}
}
}
b.tSubs[t][k] = &sub
}
if isAll {
for t := range b.tSubs {
// Don't add ALL subs to the map they're already in, and don't add it to the
// special TxErrEvent map, but we should add them to all other maps
if t != events.All {
b.tSubs[t][k] = &sub
}
}
}
return k
}
// Unsubscribe removes subscriber from broker
// this does not change the state of the subscriber.
func (b *Broker) Unsubscribe(k int) {
b.mu.Lock()
b.rmSubs(k)
b.mu.Unlock()
}
func (b *Broker) getKey() int {
if len(b.keys) > 0 {
k := b.keys[0]
b.keys = b.keys[1:] // pop first element
return k
}
return len(b.subs) + 1 // add 1 to avoid zero value
}
func (b *Broker) rmSubs(keys ...int) {
for _, k := range keys {
// if the sub doesn't exist, this could be a duplicate call
// we do not want the keys slice to contain duplicate values
// and so we have to check this first
s, ok := b.subs[k]
if !ok {
return
}
types := s.Types()
for _, t := range types {
if t == events.All {
types = nil
break
}
}
if len(types) == 0 {
// remove in all subscribers then
for _, v := range b.tSubs {
delete(v, k)
}
} else {
for _, t := range types {
delete(b.tSubs[t], k) // remove key from typed subs map
}
}
delete(b.subs, k)
b.keys = append(b.keys, k)
}
}
// SetStreaming allows the ability to toggle on and off sending events to the socketClient.
func (b *Broker) SetStreaming(on bool) bool {
old := b.canStream
b.canStream = on
return old
}
func (b *Broker) StreamingEnabled() bool {
return b.canStream && b.socketClient != nil
}
func (b *Broker) SocketClient() SocketClient {
return b.socketClient
}
func (b *Broker) fileStreamEnabled() bool {
return b.fileClient != nil
}