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configpublisher.go
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/
configpublisher.go
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// Copyright 2020 Anapaya Systems
//
// 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 control
import (
"sync"
"github.com/scionproto/scion/gateway/routing"
"github.com/scionproto/scion/pkg/addr"
"github.com/scionproto/scion/pkg/log"
)
// ConfigPublisher can be used to send configs to multiple clients via different
// means (channels, getters).
type ConfigPublisher struct {
mtx sync.RWMutex
// sessionPolicies holds the session policies that were loaded last.
sessionPolicies SessionPolicies
// routingPolicy holds the routing policy that was loaded last.
routingPolicy *routing.Policy
sessionPoliciesSubscribers []chan SessionPolicies
routingPoliciesSubscribers []chan *routing.Policy
remoteIAsSubscribers []chan []addr.IA
}
// Publish notifies clients of the Publisher about new configurations. Nil
// values are allowed and mean the nil config is not published, this is to
// allow updates of only one config.
func (n *ConfigPublisher) Publish(sp SessionPolicies, rp *routing.Policy) {
n.mtx.Lock()
defer n.mtx.Unlock()
var wg sync.WaitGroup
if sp != nil {
n.sessionPolicies = sp.Copy()
wg.Add(len(n.sessionPoliciesSubscribers))
for _, c := range n.sessionPoliciesSubscribers {
c := c
go func() {
defer log.HandlePanic()
defer wg.Done()
c <- sp.Copy()
}()
}
wg.Add(len(n.remoteIAsSubscribers))
for _, c := range n.remoteIAsSubscribers {
c := c
go func() {
defer log.HandlePanic()
defer wg.Done()
c <- sp.RemoteIAs()
}()
}
}
if rp != nil {
n.routingPolicy = rp.Copy()
wg.Add(len(n.routingPoliciesSubscribers))
for _, c := range n.routingPoliciesSubscribers {
c := c
go func() {
defer log.HandlePanic()
defer wg.Done()
c <- rp.Copy()
}()
}
}
wg.Wait()
}
// SubscribeSessionPolicies returns a channel on which new session policies will
// be sent. The channel has capacity 0. If a reader is slow to process the
// subscription, it will prevent the Publisher from publishing new
// configurations.
//
// Subscriptions happening prior to a Publish are guaranteed to return the new
// state read by the NotPublishify.
func (n *ConfigPublisher) SubscribeSessionPolicies() <-chan SessionPolicies {
n.mtx.Lock()
defer n.mtx.Unlock()
c := make(chan SessionPolicies)
n.sessionPoliciesSubscribers = append(n.sessionPoliciesSubscribers, c)
return c
}
func (n *ConfigPublisher) SubscribeRoutingPolicies() <-chan *routing.Policy {
n.mtx.Lock()
defer n.mtx.Unlock()
c := make(chan *routing.Policy)
n.routingPoliciesSubscribers = append(n.routingPoliciesSubscribers, c)
return c
}
// SubscribeRemoteIAs returns a channel on which remote IAs will
// be sent. The channel has capacity 0. If a reader is slow to process the
// subscription, it will prevent the Publisher from publishing new
// configurations.
//
// Subscriptions happening prior to a Publish are guaranteed to return the new
// state read by the NotPublishify.
func (n *ConfigPublisher) SubscribeRemoteIAs() <-chan []addr.IA {
n.mtx.Lock()
defer n.mtx.Unlock()
c := make(chan []addr.IA)
n.remoteIAsSubscribers = append(n.remoteIAsSubscribers, c)
return c
}
// RoutingPolicy returns the last routing policy that was published.
// The returned object is a deep-copy, and can be edited by the caller.
func (n *ConfigPublisher) RoutingPolicy() *routing.Policy {
n.mtx.RLock()
defer n.mtx.RUnlock()
if n.routingPolicy == nil {
return nil
}
return n.routingPolicy.Copy()
}