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controller.go
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controller.go
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// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package trafficcontrol
import (
"time"
"github.com/m3db/m3/src/cluster/kv"
"github.com/m3db/m3/src/cluster/kv/util"
"github.com/m3db/m3/src/x/watch"
"go.uber.org/atomic"
)
const (
defaultInitTimeout = 2 * time.Second
)
// Controller controls traffic.
type Controller interface {
// Allow returns true if traffic is allowed.
Allow() bool
// Init initializes the traffic controller to watch the runtime updates.
Init() error
// Close closes the traffic controller.
Close()
}
type trafficEnabler struct {
enabled *atomic.Bool
value watch.Value
opts Options
}
// NewTrafficEnabler creates a new traffic enabler.
func NewTrafficEnabler(opts Options) Controller {
enabled := atomic.NewBool(opts.DefaultValue())
iOpts := opts.InstrumentOptions()
newUpdatableFn := func() (watch.Updatable, error) {
w, err := opts.Store().Watch(opts.RuntimeKey())
return w, err
}
getFn := func(updatable watch.Updatable) (interface{}, error) {
return updatable.(kv.ValueWatch).Get(), nil
}
processFn := func(update interface{}) error {
b, err := util.BoolFromValue(
update.(kv.Value),
opts.RuntimeKey(),
opts.DefaultValue(),
util.NewOptions().SetLogger(iOpts.Logger()),
)
if err != nil {
return err
}
enabled.Store(b)
return nil
}
vOptions := watch.NewOptions().
SetInitWatchTimeout(opts.InitTimeout()).
SetInstrumentOptions(iOpts).
SetNewUpdatableFn(newUpdatableFn).
SetGetUpdateFn(getFn).
SetProcessFn(processFn)
return &trafficEnabler{
enabled: enabled,
value: watch.NewValue(vOptions),
opts: opts,
}
}
func (c *trafficEnabler) Init() error {
err := c.value.Watch()
if err == nil {
return nil
}
if _, ok := err.(watch.CreateWatchError); ok {
return err
}
return nil
}
func (c *trafficEnabler) Close() {
c.value.Unwatch()
}
func (c *trafficEnabler) Allow() bool {
return c.enabled.Load()
}
type trafficDisabler struct {
Controller
}
// NewTrafficDisabler creates a new traffic disabler.
func NewTrafficDisabler(opts Options) Controller {
return &trafficDisabler{
Controller: NewTrafficEnabler(opts),
}
}
func (c *trafficDisabler) Allow() bool {
return !c.Controller.Allow()
}