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targetlist.go
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targetlist.go
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/*
* Minio Cloud Storage, (C) 2018 Minio, 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 event
import (
"fmt"
"sync"
)
// Target - event target interface
type Target interface {
ID() TargetID
Send(Event) error
Close() error
}
// TargetList - holds list of targets indexed by target ID.
type TargetList struct {
sync.RWMutex
targets map[TargetID]Target
}
// Add - adds unique target to target list.
func (list *TargetList) Add(target Target) error {
list.Lock()
defer list.Unlock()
if _, ok := list.targets[target.ID()]; ok {
return fmt.Errorf("target %v already exists", target.ID())
}
list.targets[target.ID()] = target
return nil
}
// Exists - checks whether target by target ID exists or not.
func (list *TargetList) Exists(id TargetID) bool {
list.RLock()
defer list.RUnlock()
_, found := list.targets[id]
return found
}
// TargetIDErr returns error associated for a targetID
type TargetIDErr struct {
// ID where the remove or send were initiated.
ID TargetID
// Stores any error while removing a target or while sending an event.
Err error
}
// Remove - closes and removes targets by given target IDs.
func (list *TargetList) Remove(targetids ...TargetID) <-chan TargetIDErr {
errCh := make(chan TargetIDErr)
go func() {
defer close(errCh)
var wg sync.WaitGroup
for _, id := range targetids {
list.RLock()
target, ok := list.targets[id]
list.RUnlock()
if ok {
wg.Add(1)
go func(id TargetID, target Target) {
defer wg.Done()
if err := target.Close(); err != nil {
errCh <- TargetIDErr{
ID: id,
Err: err,
}
}
}(id, target)
}
}
wg.Wait()
list.Lock()
for _, id := range targetids {
delete(list.targets, id)
}
list.Unlock()
}()
return errCh
}
// List - returns available target IDs.
func (list *TargetList) List() []TargetID {
list.RLock()
defer list.RUnlock()
keys := []TargetID{}
for k := range list.targets {
keys = append(keys, k)
}
return keys
}
// Send - sends events to targets identified by target IDs.
func (list *TargetList) Send(event Event, targetIDs ...TargetID) <-chan TargetIDErr {
errCh := make(chan TargetIDErr)
go func() {
defer close(errCh)
var wg sync.WaitGroup
for _, id := range targetIDs {
list.RLock()
target, ok := list.targets[id]
list.RUnlock()
if ok {
wg.Add(1)
go func(id TargetID, target Target) {
defer wg.Done()
if err := target.Send(event); err != nil {
errCh <- TargetIDErr{
ID: id,
Err: err,
}
}
}(id, target)
}
}
wg.Wait()
}()
return errCh
}
// NewTargetList - creates TargetList.
func NewTargetList() *TargetList {
return &TargetList{targets: make(map[TargetID]Target)}
}