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hub.go
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hub.go
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// Copyright 2019 Drone IO, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package pubsub
import (
"context"
"sync"
"github.com/drone/drone/core"
)
type hub struct {
sync.Mutex
subs map[*subscriber]struct{}
}
// New creates a new publish subscriber.
func New() core.Pubsub {
return &hub{
subs: map[*subscriber]struct{}{},
}
}
func (h *hub) Publish(ctx context.Context, e *core.Message) error {
h.Lock()
for s := range h.subs {
s.publish(e)
}
h.Unlock()
return nil
}
func (h *hub) Subscribe(ctx context.Context) (<-chan *core.Message, <-chan error) {
h.Lock()
s := &subscriber{
handler: make(chan *core.Message, 100),
quit: make(chan struct{}),
}
h.subs[s] = struct{}{}
h.Unlock()
errc := make(chan error)
go func() {
defer close(errc)
select {
case <-ctx.Done():
h.Lock()
delete(h.subs, s)
h.Unlock()
s.close()
}
}()
return s.handler, errc
}
func (h *hub) Subscribers() int {
h.Lock()
c := len(h.subs)
h.Unlock()
return c
}