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reload.go
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reload.go
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package cfgfile
import (
"expvar"
"path/filepath"
"sync"
"time"
"github.com/elastic/beats/libbeat/common"
"github.com/elastic/beats/libbeat/logp"
"github.com/elastic/beats/libbeat/paths"
)
var (
DefaultReloadConfig = ReloadConfig{
Reload: Reload{
Period: 10 * time.Second,
Enabled: false,
},
}
debugf = logp.MakeDebug("cfgfile")
configReloads = expvar.NewInt("libbeat.config.reloads")
moduleStarts = expvar.NewInt("libbeat.config.module.starts")
moduleStops = expvar.NewInt("libbeat.config.module.stops")
moduleRunning = expvar.NewInt("libbeat.config.module.running")
)
type ReloadConfig struct {
// If path is a relative path, it is relative to the ${path.config}
Path string `config:"path"`
Reload Reload `config:"reload"`
}
type Reload struct {
Period time.Duration `config:"period"`
Enabled bool `config:"enabled"`
}
type RunnerFactory interface {
Create(*common.Config) (Runner, error)
}
type Runner interface {
Start()
Stop()
ID() uint64
}
// Reloader is used to register and reload modules
type Reloader struct {
registry *Registry
config ReloadConfig
done chan struct{}
wg sync.WaitGroup
}
// NewReloader creates new Reloader instance for the given config
func NewReloader(cfg *common.Config) *Reloader {
config := DefaultReloadConfig
cfg.Unpack(&config)
return &Reloader{
registry: NewRegistry(),
config: config,
done: make(chan struct{}),
}
}
// Run runs the reloader
func (rl *Reloader) Run(runnerFactory RunnerFactory) {
logp.Info("Config reloader started")
rl.wg.Add(1)
defer rl.wg.Done()
// Stop all running modules when method finishes
defer rl.stopRunners(rl.registry.CopyList())
path := rl.config.Path
if !filepath.IsAbs(path) {
path = paths.Resolve(paths.Config, path)
}
gw := NewGlobWatcher(path)
for {
select {
case <-rl.done:
logp.Info("Dynamic config reloader stopped")
return
case <-time.After(rl.config.Reload.Period):
debugf("Scan for new config files")
configReloads.Add(1)
files, updated, err := gw.Scan()
if err != nil {
// In most cases of error, updated == false, so will continue
// to next iteration below
logp.Err("Error fetching new config files: %v", err)
}
// no file changes
if !updated {
continue
}
// Load all config objects
configs := []*common.Config{}
for _, file := range files {
c, err := LoadList(file)
if err != nil {
logp.Err("Error loading config: %s", err)
continue
}
configs = append(configs, c...)
}
debugf("Number of module configs found: %v", len(configs))
startList := map[uint64]Runner{}
stopList := rl.registry.CopyList()
for _, c := range configs {
// Only add configs to startList which are enabled
if !c.Enabled() {
continue
}
runner, err := runnerFactory.Create(c)
if err != nil {
logp.Err("Error creating module: %s", err)
continue
}
debugf("Remove module from stoplist: %v", runner.ID())
delete(stopList, runner.ID())
// As module already exist, it must be removed from the stop list and not started
if !rl.registry.Has(runner.ID()) {
debugf("Add module to startlist: %v", runner.ID())
startList[runner.ID()] = runner
continue
}
}
rl.stopRunners(stopList)
rl.startRunners(startList)
}
}
}
// Stop stops the reloader and waits for all modules to properly stop
func (rl *Reloader) Stop() {
close(rl.done)
rl.wg.Wait()
}
func (rl *Reloader) startRunners(list map[uint64]Runner) {
logp.Info("Starting %v runners ...", len(list))
for id, runner := range list {
runner.Start()
rl.registry.Add(id, runner)
moduleStarts.Add(1)
moduleRunning.Add(1)
debugf("New runner started: %v", id)
}
}
func (rl *Reloader) stopRunners(list map[uint64]Runner) {
logp.Info("Stopping %v runners ...", len(list))
wg := sync.WaitGroup{}
for hash, runner := range list {
wg.Add(1)
// Stop modules in parallel
go func(h uint64, run Runner) {
defer func() {
moduleStops.Add(1)
moduleRunning.Add(-1)
debugf("Runner stopped: %v", h)
wg.Done()
}()
run.Stop()
rl.registry.Remove(h)
}(hash, runner)
}
wg.Wait()
}