/
pubsub.go
215 lines (176 loc) · 3.29 KB
/
pubsub.go
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package pubsub
import (
"errors"
"sync"
"github.com/benburkert/pubsub/abool"
)
var (
errClosed = errors.New("PubSub is closed")
errMaxSub = errors.New("maxSubCount reached")
)
type MarkerChan chan struct{}
type PubSub struct {
buffer *Buffer
donec MarkerChan
doneo sync.Once
doneb abool.Value
pubwg sync.WaitGroup
subwg sync.WaitGroup
submu sync.Mutex
subCount, subMax int
}
func New(minBufferSize, maxSubCount int) (*PubSub, error) {
if minBufferSize < 2 {
return nil, errors.New("minBufferSize must be > 1")
}
if maxSubCount < 1 {
return nil, errors.New("maxSubCount must be > 0")
}
return &PubSub{
buffer: NewBuffer(minBufferSize, maxSubCount),
donec: make(MarkerChan),
doneb: abool.New(false),
subMax: maxSubCount,
}, nil
}
func (ps *PubSub) AddPublisher(pub Publisher) error {
if ps.isClosed() {
return errClosed
}
ps.pubwg.Add(1)
ctx := &Context{
Buffer: ps.buffer,
Done: ps.donec,
Close: ps.pubwg.Done,
}
return pub.PublishTo(ctx)
}
func (ps *PubSub) AddSubscriber(sub Subscriber) error {
if ps.isClosed() {
return errClosed
}
if !ps.addSub() {
return errMaxSub
}
ctx := &Context{
Buffer: ps.buffer,
Done: ps.donec,
Close: ps.delSub,
}
return sub.SubscribeTo(ctx)
}
func (ps *PubSub) Close() {
ps.doneo.Do(func() {
ps.buffer.Write(ps.donec)
ps.doneb.Set()
close(ps.donec)
})
ps.pubwg.Wait()
ps.subwg.Wait()
}
func (ps *PubSub) Pub(v interface{}) error {
if ps.isClosed() {
return errClosed
}
ps.buffer.Write(v)
return nil
}
func (ps *PubSub) PubChan(ch <-chan interface{}) (<-chan struct{}, error) {
if ps.isClosed() {
return nil, errClosed
}
ps.pubwg.Add(1)
go func() {
defer ps.pubwg.Done()
for {
select {
case v := <-ch:
ps.buffer.Write(v)
case <-ps.donec:
for v := range ch {
ps.buffer.Write(v)
}
return
}
}
}()
return ps.donec, nil
}
func (ps *PubSub) PubSlice(vs []interface{}) error {
if ps.isClosed() {
return errClosed
}
ps.buffer.WriteSlice(vs)
return nil
}
func (ps *PubSub) SubChan(ch chan<- interface{}) (chan<- struct{}, error) {
if ps.isClosed() {
return nil, errClosed
}
if !ps.addSub() {
return nil, errMaxSub
}
unsubc := make(MarkerChan)
go func() {
<-unsubc
ps.Pub(unsubc)
}()
rfn := func(v interface{}) bool {
if vch, ok := v.(MarkerChan); ok {
if vch == ps.donec || vch == unsubc {
close(ch)
ps.delSub()
return false
}
} else {
ch <- v
}
return true
}
ps.buffer.ReadTo(rfn)
return unsubc, nil
}
func (ps *PubSub) SubFunc(fn func(interface{})) (func(), error) {
if ps.isClosed() {
return nil, errClosed
}
if !ps.addSub() {
return nil, errMaxSub
}
unsubc := make(MarkerChan)
unsubfn := func() {
ps.Pub(unsubc)
}
rfn := func(v interface{}) bool {
if vch, ok := v.(MarkerChan); ok {
if vch == ps.donec || vch == unsubc {
ps.delSub()
return false
}
} else {
fn(v)
}
return true
}
ps.buffer.ReadTo(rfn)
return unsubfn, nil
}
func (ps *PubSub) addSub() bool {
ps.submu.Lock()
defer ps.submu.Unlock()
if ps.subCount == ps.subMax {
return false
}
ps.subCount++
ps.subwg.Add(1)
return true
}
func (ps *PubSub) delSub() {
ps.submu.Lock()
defer ps.submu.Unlock()
ps.subCount--
ps.subwg.Done()
}
func (ps *PubSub) isClosed() bool {
return ps.doneb.Test()
}