Fix issues related to Ring

- RingConsumer is now used directly in the goroutine responsible for
  writing downstream messages. This allows the ring buffer not to be
  consumed on write error.
- RingConsumer now has a channel attached. This allows PRIVMSG messages
  to always use RingConsumer, instead of also directly pushing messages
  to all downstream connections.
- Multiple clients with the same history name are now supported.
- Ring is now protected by a mutex
This commit is contained in:
Simon Ser 2020-02-17 15:46:29 +01:00
parent 2a43dbd71a
commit 9a93c56cdf
No known key found for this signature in database
GPG Key ID: 0FDE7BE0E88F5E48
4 changed files with 159 additions and 56 deletions

View File

@ -45,10 +45,11 @@ type downstreamConn struct {
srv *Server
logger Logger
messages chan *irc.Message
consumers chan *RingConsumer
closed chan struct{}
registered bool
user *user
closed bool
nick string
username string
realname string
@ -61,6 +62,8 @@ func newDownstreamConn(srv *Server, netConn net.Conn) *downstreamConn {
srv: srv,
logger: &prefixLogger{srv.Logger, fmt.Sprintf("downstream %q: ", netConn.RemoteAddr())},
messages: make(chan *irc.Message, 64),
consumers: make(chan *RingConsumer),
closed: make(chan struct{}),
}
go func() {
@ -85,6 +88,15 @@ func (dc *downstreamConn) prefix() *irc.Prefix {
}
}
func (dc *downstreamConn) isClosed() bool {
select {
case <-dc.closed:
return true
default:
return false
}
}
func (dc *downstreamConn) readMessages() error {
dc.logger.Printf("new connection")
@ -104,7 +116,7 @@ func (dc *downstreamConn) readMessages() error {
return fmt.Errorf("failed to handle IRC command %q: %v", msg.Command, err)
}
if dc.closed {
if dc.isClosed() {
return nil
}
}
@ -113,16 +125,39 @@ func (dc *downstreamConn) readMessages() error {
}
func (dc *downstreamConn) writeMessages() error {
for msg := range dc.messages {
if err := dc.irc.WriteMessage(msg); err != nil {
for {
var err error
var closed bool
select {
case msg := <-dc.messages:
err = dc.irc.WriteMessage(msg)
case consumer := <-dc.consumers:
for {
msg := consumer.Peek()
if msg == nil {
break
}
err = dc.irc.WriteMessage(msg)
if err != nil {
break
}
consumer.Consume()
}
case <-dc.closed:
closed = true
}
if err != nil {
return err
}
if closed {
break
}
}
return nil
}
func (dc *downstreamConn) Close() error {
if dc.closed {
if dc.isClosed() {
return fmt.Errorf("downstream connection already closed")
}
@ -134,17 +169,9 @@ func (dc *downstreamConn) Close() error {
}
}
u.lock.Unlock()
// TODO: figure out a better way to advance the ring buffer consumer cursor
u.forEachUpstream(func(uc *upstreamConn) {
// TODO: let clients specify the ring buffer name in their username
uc.ring.Consumer("").Reset()
})
}
close(dc.messages)
dc.closed = true
close(dc.closed)
return nil
}
@ -211,6 +238,7 @@ func (dc *downstreamConn) register() error {
dc.user = u
u.lock.Lock()
firstDownstream := len(u.downstreamConns) == 0
u.downstreamConns = append(u.downstreamConns, dc)
u.lock.Unlock()
@ -249,15 +277,41 @@ func (dc *downstreamConn) register() error {
}
// TODO: let clients specify the ring buffer name in their username
consumer := uc.ring.Consumer("")
historyName := ""
var seqPtr *uint64
if firstDownstream {
seq, ok := uc.history[historyName]
if ok {
seqPtr = &seq
}
}
consumer, ch := uc.ring.Consumer(seqPtr)
go func() {
for {
// TODO: these messages will get lost if the connection is closed
msg := consumer.Consume()
if msg == nil {
var closed bool
select {
case <-ch:
dc.consumers <- consumer
case <-dc.closed:
closed = true
}
if closed {
break
}
dc.SendMessage(msg)
}
seq := consumer.Close()
dc.user.lock.Lock()
lastDownstream := len(dc.user.downstreamConns) == 0
dc.user.lock.Unlock()
if lastDownstream {
uc.history[historyName] = seq
}
}()
})
return nil

77
ring.go
View File

@ -1,6 +1,8 @@
package jounce
import (
"sync"
"gopkg.in/irc.v3"
)
@ -8,45 +10,68 @@ import (
// buffer size is fixed. The ring buffer is stored in memory.
type Ring struct {
buffer []*irc.Message
cap, cur uint64
cap uint64
consumers map[string]*RingConsumer
lock sync.Mutex
cur uint64
consumers []*RingConsumer
}
func NewRing(capacity int) *Ring {
return &Ring{
buffer: make([]*irc.Message, capacity),
cap: uint64(capacity),
consumers: make(map[string]*RingConsumer),
}
}
func (r *Ring) Produce(msg *irc.Message) {
r.lock.Lock()
defer r.lock.Unlock()
i := int(r.cur % r.cap)
r.buffer[i] = msg
r.cur++
for _, consumer := range r.consumers {
select {
case consumer.ch <- struct{}{}:
// This space is intentionally left blank
default:
// The channel already has a pending item
}
}
}
func (r *Ring) Consumer(name string) *RingConsumer {
consumer, ok := r.consumers[name]
if ok {
return consumer
}
consumer = &RingConsumer{
func (r *Ring) Consumer(seq *uint64) (*RingConsumer, <-chan struct{}) {
consumer := &RingConsumer{
ring: r,
cur: r.cur,
ch: make(chan struct{}, 1),
}
r.consumers[name] = consumer
return consumer
r.lock.Lock()
if seq != nil {
consumer.cur = *seq
} else {
consumer.cur = r.cur
}
if consumer.diff() > 0 {
consumer.ch <- struct{}{}
}
r.consumers = append(r.consumers, consumer)
r.lock.Unlock()
return consumer, consumer.ch
}
type RingConsumer struct {
ring *Ring
cur uint64
ch chan struct{}
closed bool
}
func (rc *RingConsumer) Diff() uint64 {
// diff returns the number of pending messages. It assumes the Ring is locked.
func (rc *RingConsumer) diff() uint64 {
if rc.cur > rc.ring.cur {
panic("jounce: consumer cursor greater than producer cursor")
}
@ -54,7 +79,14 @@ func (rc *RingConsumer) Diff() uint64 {
}
func (rc *RingConsumer) Peek() *irc.Message {
diff := rc.Diff()
if rc.closed {
panic("jounce: RingConsumer.Peek called after Close")
}
rc.ring.lock.Lock()
defer rc.ring.lock.Unlock()
diff := rc.diff()
if diff == 0 {
return nil
}
@ -78,6 +110,17 @@ func (rc *RingConsumer) Consume() *irc.Message {
return msg
}
func (rc *RingConsumer) Reset() {
rc.cur = rc.ring.cur
func (rc *RingConsumer) Close() uint64 {
rc.ring.lock.Lock()
for i := range rc.ring.consumers {
if rc.ring.consumers[i] == rc {
rc.ring.consumers = append(rc.ring.consumers[:i], rc.ring.consumers[i+1:]...)
break
}
}
rc.ring.lock.Unlock()
close(rc.ch)
rc.closed = true
return rc.cur
}

View File

@ -40,6 +40,13 @@ type user struct {
downstreamConns []*downstreamConn
}
func newUser(srv *Server, username string) *user {
return &user{
username: username,
srv: srv,
}
}
func (u *user) forEachUpstream(f func(uc *upstreamConn)) {
u.lock.Lock()
for _, uc := range u.upstreamConns {
@ -116,7 +123,7 @@ func (s *Server) prefix() *irc.Prefix {
func (s *Server) Run() {
// TODO: multi-user
u := &user{username: "jounce", srv: s}
u := newUser(s, "jounce")
s.lock.Lock()
s.users[u.username] = u

View File

@ -44,6 +44,7 @@ type upstreamConn struct {
closed bool
modes modeSet
channels map[string]*upstreamChannel
history map[string]uint64
}
func connectToUpstream(u *user, upstream *Upstream) (*upstreamConn, error) {
@ -66,6 +67,7 @@ func connectToUpstream(u *user, upstream *Upstream) (*upstreamConn, error) {
messages: msgs,
ring: NewRing(u.srv.RingCap),
channels: make(map[string]*upstreamChannel),
history: make(map[string]uint64),
}
go func() {
@ -305,9 +307,6 @@ func (uc *upstreamConn) handleMessage(msg *irc.Message) error {
})
case "PRIVMSG":
uc.ring.Produce(msg)
uc.user.forEachDownstream(func(dc *downstreamConn) {
dc.SendMessage(msg)
})
case irc.RPL_YOURHOST, irc.RPL_CREATED:
// Ignore
case irc.RPL_LUSERCLIENT, irc.RPL_LUSEROP, irc.RPL_LUSERUNKNOWN, irc.RPL_LUSERCHANNELS, irc.RPL_LUSERME: