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registrar.go
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registrar.go
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package registrar
import (
"encoding/json"
"fmt"
"os"
"path/filepath"
"sync"
"time"
"github.com/elastic/beats/filebeat/input/file"
helper "github.com/elastic/beats/libbeat/common/file"
"github.com/elastic/beats/libbeat/logp"
"github.com/elastic/beats/libbeat/monitoring"
"github.com/elastic/beats/libbeat/paths"
)
type Registrar struct {
Channel chan []file.State
out successLogger
done chan struct{}
registryFile string // Path to the Registry File
wg sync.WaitGroup
states *file.States // Map with all file paths inside and the corresponding state
flushTimeout time.Duration
bufferedStateUpdates int
}
type successLogger interface {
Published(n int) bool
}
var (
statesUpdate = monitoring.NewInt(nil, "registrar.states.update")
statesCleanup = monitoring.NewInt(nil, "registrar.states.cleanup")
statesCurrent = monitoring.NewInt(nil, "registrar.states.current")
registryWrites = monitoring.NewInt(nil, "registrar.writes")
)
func New(registryFile string, flushTimeout time.Duration, out successLogger) (*Registrar, error) {
r := &Registrar{
registryFile: registryFile,
done: make(chan struct{}),
states: file.NewStates(),
Channel: make(chan []file.State, 1),
flushTimeout: flushTimeout,
out: out,
wg: sync.WaitGroup{},
}
err := r.Init()
return r, err
}
// Init sets up the Registrar and make sure the registry file is setup correctly
func (r *Registrar) Init() error {
// The registry file is opened in the data path
r.registryFile = paths.Resolve(paths.Data, r.registryFile)
// Create directory if it does not already exist.
registryPath := filepath.Dir(r.registryFile)
err := os.MkdirAll(registryPath, 0750)
if err != nil {
return fmt.Errorf("Failed to created registry file dir %s: %v", registryPath, err)
}
// Check if files exists
fileInfo, err := os.Lstat(r.registryFile)
if os.IsNotExist(err) {
logp.Info("No registry file found under: %s. Creating a new registry file.", r.registryFile)
// No registry exists yet, write empty state to check if registry can be written
return r.writeRegistry()
}
if err != nil {
return err
}
// Check if regular file, no dir, no symlink
if !fileInfo.Mode().IsRegular() {
// Special error message for directory
if fileInfo.IsDir() {
return fmt.Errorf("Registry file path must be a file. %s is a directory.", r.registryFile)
}
return fmt.Errorf("Registry file path is not a regular file: %s", r.registryFile)
}
logp.Info("Registry file set to: %s", r.registryFile)
return nil
}
// GetStates return the registrar states
func (r *Registrar) GetStates() []file.State {
return r.states.GetStates()
}
// loadStates fetches the previous reading state from the configure RegistryFile file
// The default file is `registry` in the data path.
func (r *Registrar) loadStates() error {
f, err := os.Open(r.registryFile)
if err != nil {
return err
}
defer f.Close()
logp.Info("Loading registrar data from %s", r.registryFile)
decoder := json.NewDecoder(f)
states := []file.State{}
err = decoder.Decode(&states)
if err != nil {
return fmt.Errorf("Error decoding states: %s", err)
}
states = resetStates(states)
r.states.SetStates(states)
logp.Info("States Loaded from registrar: %+v", len(states))
return nil
}
// resetStates sets all states to finished and disable TTL on restart
// For all states covered by a prospector, TTL will be overwritten with the prospector value
func resetStates(states []file.State) []file.State {
for key, state := range states {
state.Finished = true
// Set ttl to -2 to easily spot which states are not managed by a prospector
state.TTL = -2
states[key] = state
}
return states
}
func (r *Registrar) Start() error {
// Load the previous log file locations now, for use in prospector
err := r.loadStates()
if err != nil {
return fmt.Errorf("Error loading state: %v", err)
}
r.wg.Add(1)
go r.Run()
return nil
}
func (r *Registrar) Run() {
logp.Info("Starting Registrar")
// Writes registry on shutdown
defer func() {
r.writeRegistry()
r.wg.Done()
}()
var (
timer *time.Timer
flushC <-chan time.Time
)
for {
select {
case <-r.done:
logp.Info("Ending Registrar")
return
case <-flushC:
flushC = nil
timer.Stop()
r.flushRegistry()
case states := <-r.Channel:
r.onEvents(states)
if r.flushTimeout <= 0 {
r.flushRegistry()
} else if flushC == nil {
timer = time.NewTimer(r.flushTimeout)
flushC = timer.C
}
}
}
}
// onEvents processes events received from the publisher pipeline
func (r *Registrar) onEvents(states []file.State) {
r.processEventStates(states)
beforeCount := r.states.Count()
cleanedStates := r.states.Cleanup()
statesCleanup.Add(int64(cleanedStates))
r.bufferedStateUpdates += len(states)
logp.Debug("registrar",
"Registrar states cleaned up. Before: %d, After: %d",
beforeCount, beforeCount-cleanedStates)
}
// processEventStates gets the states from the events and writes them to the registrar state
func (r *Registrar) processEventStates(states []file.State) {
logp.Debug("registrar", "Processing %d events", len(states))
for i := range states {
r.states.Update(states[i])
statesUpdate.Add(1)
}
}
// Stop stops the registry. It waits until Run function finished.
func (r *Registrar) Stop() {
logp.Info("Stopping Registrar")
close(r.done)
r.wg.Wait()
}
func (r *Registrar) flushRegistry() {
if err := r.writeRegistry(); err != nil {
logp.Err("Writing of registry returned error: %v. Continuing...", err)
}
if r.out != nil {
r.out.Published(r.bufferedStateUpdates)
}
r.bufferedStateUpdates = 0
}
// writeRegistry writes the new json registry file to disk.
func (r *Registrar) writeRegistry() error {
logp.Debug("registrar", "Write registry file: %s", r.registryFile)
tempfile := r.registryFile + ".new"
f, err := os.OpenFile(tempfile, os.O_RDWR|os.O_CREATE|os.O_TRUNC|os.O_SYNC, 0600)
if err != nil {
logp.Err("Failed to create tempfile (%s) for writing: %s", tempfile, err)
return err
}
// First clean up states
states := r.states.GetStates()
encoder := json.NewEncoder(f)
err = encoder.Encode(states)
if err != nil {
f.Close()
logp.Err("Error when encoding the states: %s", err)
return err
}
// Directly close file because of windows
f.Close()
err = helper.SafeFileRotate(r.registryFile, tempfile)
logp.Debug("registrar", "Registry file updated. %d states written.", len(states))
registryWrites.Add(1)
statesCurrent.Set(int64(len(states)))
return err
}