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manager.go
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manager.go
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// Copyright 2023 The ClusterLink 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 runnable
import (
"errors"
"fmt"
"sync"
"github.com/sirupsen/logrus"
)
// Runnable represents a runnable instance.
type Instance interface {
Name() string
Start() error
Stop() error
GracefulStop() error
}
// Server represents a runnable server.
type Server interface {
Instance
Listen(address string) error
Close() error
}
// Manager manages a set of runnables.
type Manager struct {
lock sync.Mutex
runnables []Instance
serverAddress map[Server]string
errors map[Instance]error
logger *logrus.Entry
}
// AddServer adds a new server.
func (c *Manager) AddServer(listenAddress string, server Server) {
c.Add(server)
c.serverAddress[server] = listenAddress
}
// Add a new runnable.
func (c *Manager) Add(runnable Instance) {
c.runnables = append(c.runnables, runnable)
}
// Run starts all runnables.
func (c *Manager) Run() error {
defer func() {
// close all servers
for server := range c.serverAddress {
if err := server.Close(); err != nil {
c.logger.Warnf("Error closing server '%s': %v.", server.Name(), err)
}
}
}()
// start server listeners
for server, listenAddress := range c.serverAddress {
if err := server.Listen(listenAddress); err != nil {
return fmt.Errorf("unable to create listener for server '%s' on %s: %w",
server.Name(), listenAddress, err)
}
}
lock := &sync.Mutex{}
stop := sync.NewCond(lock)
// goroutine for stopping all runnables if one fails
go func(stop *sync.Cond) {
stop.L.Lock()
stop.Wait()
stop.L.Unlock()
c.lock.Lock()
pending := len(c.errors) < len(c.runnables)
c.lock.Unlock()
if pending {
if err := c.Stop(); err != nil {
c.logger.Warnf("Error stopping: %v.", err)
} else {
c.logger.Infof("Asked all runnables to stop.")
}
}
}(stop)
// initialize wait group
wg := &sync.WaitGroup{}
wg.Add(len(c.runnables))
// start runnables in goroutines
for _, runnable := range c.runnables {
go func(runnable Instance) {
defer wg.Done()
c.logger.Infof("Starting runnable '%s'.", runnable.Name())
err := runnable.Start()
c.logger.Infof("Runnable '%s' stopped: %v.", runnable.Name(), err)
c.lock.Lock()
c.errors[runnable] = err
c.lock.Unlock()
if err != nil {
// signal to stop other runnables
stop.Signal()
}
}(runnable)
}
// wait for all runnables to stop
wg.Wait()
// terminate error-waiting goroutine
stop.Signal()
// collect and return errors
var errs []error
for runnable, err := range c.errors {
if err != nil {
errs = append(errs, fmt.Errorf(
"error running '%s': %w", runnable.Name(), err))
}
}
return errors.Join(errs...)
}
// Stop all runnables.
func (c *Manager) Stop() error {
c.logger.Info("Stopping.")
var errs []error
for _, runnable := range c.runnables {
if err := runnable.Stop(); err != nil {
errs = append(errs, fmt.Errorf(
"unable to stop '%s': %w", runnable.Name(), err))
}
}
return errors.Join(errs...)
}
// GracefulStop gracefully stops all runnables.
func (c *Manager) GracefulStop() error {
c.logger.Info("Gracefully stopping.")
var errs []error
for _, runnable := range c.runnables {
if err := runnable.GracefulStop(); err != nil {
errs = append(errs, fmt.Errorf(
"unable to gracefully stop '%s': %w", runnable.Name(), err))
}
}
return errors.Join(errs...)
}
// NewManager returns a new empty runnable manager.
func NewManager() *Manager {
return &Manager{
serverAddress: make(map[Server]string),
errors: make(map[Instance]error),
logger: logrus.WithField("component", "util.controller"),
}
}