forked from istio/istio
/
distributor.go
129 lines (109 loc) · 3.43 KB
/
distributor.go
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// Copyright 2019 Istio Authors
//
// 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 runtime
import (
"sync"
sn "istio.io/istio/pkg/mcp/snapshot"
)
// Distributor interface allows processor to distribute snapshots of configuration.
type Distributor interface {
SetSnapshot(name string, snapshot sn.Snapshot)
ClearSnapshot(name string)
}
// InMemoryDistributor is an in-memory distributor implementation.
type InMemoryDistributor struct {
snapshotsLock sync.Mutex
snapshots map[string]sn.Snapshot
listenersLock sync.Mutex
listeners []*listenerEntry
}
type listenerEntry struct {
// action that the listener want to take once it get notified
action ListenerFn
// channel used to receive snapshot
snapshotChan chan sn.Snapshot
}
// ListenerFn is used by listeners for defining listen action
type ListenerFn func(s sn.Snapshot)
var _ Distributor = &InMemoryDistributor{}
// NewInMemoryDistributor returns a new instance of InMemoryDistributor
func NewInMemoryDistributor() *InMemoryDistributor {
return &InMemoryDistributor{
snapshots: make(map[string]sn.Snapshot),
}
}
// SetSnapshot is an implementation of Distributor.SetSnapshot
func (d *InMemoryDistributor) SetSnapshot(name string, snapshot sn.Snapshot) {
d.snapshotsLock.Lock()
defer d.snapshotsLock.Unlock()
d.snapshots[name] = snapshot
d.notifyListeners(snapshot)
}
// ClearSnapshot is an implementation of Distributor.ClearSnapshot
func (d *InMemoryDistributor) ClearSnapshot(name string) {
d.snapshotsLock.Lock()
defer d.snapshotsLock.Unlock()
delete(d.snapshots, name)
}
// GetSnapshot get the snapshot of the specified name
func (d *InMemoryDistributor) GetSnapshot(name string) sn.Snapshot {
d.snapshotsLock.Lock()
defer d.snapshotsLock.Unlock()
if s, ok := d.snapshots[name]; ok {
return s
}
return nil
}
// NumSnapshots returns the current number of snapshots.
func (d *InMemoryDistributor) NumSnapshots() int {
return len(d.snapshots)
}
// ListenChanges registered listener and start listening snapshot changes in the distributor
func (d *InMemoryDistributor) ListenChanges(cancel chan bool, fn ListenerFn) {
snapshotChan := make(chan sn.Snapshot, 1)
l := &listenerEntry{fn, snapshotChan}
d.listenersLock.Lock()
d.listeners = append(d.listeners, l)
d.listenersLock.Unlock()
for {
select {
case <-cancel:
d.deleteListener(l)
close(snapshotChan)
return
case s := <-snapshotChan:
fn(s)
}
}
}
// Called internally when a snapshot is set
func (d *InMemoryDistributor) notifyListeners(s sn.Snapshot) {
d.listenersLock.Lock()
defer d.listenersLock.Unlock()
for _, l := range d.listeners {
l.snapshotChan <- s
}
}
// Called internally when a listener is stopped
func (d *InMemoryDistributor) deleteListener(l *listenerEntry) {
d.listenersLock.Lock()
defer d.listenersLock.Unlock()
for i := len(d.listeners) - 1; i >= 0; i-- {
if d.listeners[i] == l {
d.listeners = append(d.listeners[:i], d.listeners[i+1:]...)
l = nil
return
}
}
}