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publish.go
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publish.go
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// Copyright (c) 2019-2020 Zededa, Inc.
// SPDX-License-Identifier: Apache-2.0
package socketdriver
import (
"encoding/base64"
"errors"
"fmt"
"io/ioutil"
"net"
"os"
"strconv"
"strings"
"time"
"github.com/lf-edge/eve/pkg/pillar/base"
"github.com/lf-edge/eve/pkg/pillar/pubsub"
fileutils "github.com/lf-edge/eve/pkg/pillar/utils/file"
logutils "github.com/lf-edge/eve/pkg/pillar/utils/logging"
"github.com/sirupsen/logrus"
)
// Publisher implementation of `pubsub.DriverPublisher` for `SocketDriver`.
// Implements Unix-domain socket or directory publication,
// and directory-based persistence.
type Publisher struct {
persistent bool
sock net.Conn // For socket subscriptions
sockName string // there is one socket per publishing agent
listener net.Listener
dirName string
shouldPopulate bool // indicate on start if we need to populate
name string
topic string
updaters *pubsub.Updaters
differ pubsub.Differ
restarted pubsub.Restarted
logger *logrus.Logger
log *base.LogObject
doneChan chan struct{}
rootDir string
}
// Publish publish a key-value pair
func (s *Publisher) Publish(key string, item []byte) error {
if len(item) == 0 {
return fmt.Errorf("empty content published for %s/%s", s.name, key)
}
fileName := s.dirName + "/" + key + ".json"
s.log.Tracef("Publish writing %s\n", fileName)
var err error
if s.persistent {
err = fileutils.WriteRenameWithBackup(fileName, item)
} else {
err = fileutils.WriteRename(fileName, item)
}
if err != nil {
return err
}
return nil
}
// Unpublish delete a key and publish its deletion
func (s *Publisher) Unpublish(key string) error {
fileName := s.dirName + "/" + key + ".json"
s.log.Tracef("Unpublish deleting file %s\n", fileName)
// First remove backup file so that unpublished item will not be accidentally recovered.
if s.persistent {
err := os.Remove(fileName + ".bak")
// Ignore if backup file is missing.
if err != nil && !os.IsNotExist(err) {
return fmt.Errorf("Unpublish(%s/%s): failed to remove backup: %w",
s.name, key, err)
}
}
if err := os.Remove(fileName); err != nil {
return fmt.Errorf("Unpublish(%s/%s): failed: %w", s.name, key, err)
}
if err := fileutils.DirSync(s.dirName); err != nil {
return fmt.Errorf("Unpublish(%s/%s): failed to sync directory %s: %w",
s.name, key, s.dirName, err)
}
return nil
}
// Load load entire persisted data set into a map
func (s *Publisher) Load() (map[string][]byte, int, error) {
dirName := s.dirName
restartCounter := 0
items := make(map[string][]byte)
s.log.Tracef("Load(%s)\n", s.name)
files, err := ioutil.ReadDir(dirName)
if err != nil {
// Drive on?
s.log.Error(err)
return items, restartCounter, err
}
for _, file := range files {
if !strings.HasSuffix(file.Name(), ".json") {
if file.Name() == "restarted" {
statusFile := dirName + "/" + file.Name()
sb, err := ioutil.ReadFile(statusFile)
if err != nil {
s.log.Errorf("Load: %s for %s\n", err, statusFile)
continue
}
restartCounter, err = strconv.Atoi(string(sb))
// Treat present but empty file as "1" to
// handle old file in /persist
if err != nil {
s.log.Warnf("Load: %s for %s; treat as 1", err, statusFile)
restartCounter = 1
}
}
continue
}
// Remove .json from name */
key := strings.Split(file.Name(), ".json")[0]
statusFile := dirName + "/" + file.Name()
if _, err := os.Stat(statusFile); err != nil {
// File just vanished!
s.log.Errorf("populate: File disappeared <%s>\n",
statusFile)
continue
}
s.log.Tracef("Load found key %s file %s\n", key, statusFile)
sb, err := ioutil.ReadFile(statusFile)
if err != nil {
s.log.Errorf("Load: %s for %s\n", err, statusFile)
continue
}
if len(sb) == 0 {
s.log.Errorf("Load: %s is empty", statusFile)
continue
}
items[key] = sb
}
// Try to recover lost items (have backup but missing the original).
if s.persistent {
const backupSuffix = ".json.bak"
var keysToRecover []string
for _, file := range files {
if strings.HasSuffix(file.Name(), backupSuffix) {
key := strings.TrimSuffix(file.Name(), backupSuffix)
if _, loaded := items[key]; !loaded {
keysToRecover = append(keysToRecover, key)
}
}
}
for _, key := range keysToRecover {
sb, err := s.recoverFromBackup(key)
if err != nil {
s.log.Errorf("Failed to recover %s/%s: %v", s.name, key, err)
continue
}
items[key] = sb
s.log.Warnf("Using backup of %s/%s", s.name, key)
}
}
return items, restartCounter, err
}
// recoverFromBackup tries to recover lost item from a backup file.
// Called when the original file is missing or empty.
func (s *Publisher) recoverFromBackup(key string) ([]byte, error) {
origFileName := s.dirName + "/" + key + ".json"
backupFileName := origFileName + ".bak"
bakData, err := ioutil.ReadFile(backupFileName)
if err != nil {
err = fmt.Errorf("failed to read backup file %s: %w", backupFileName, err)
return nil, err
}
if len(bakData) == 0 {
err = fmt.Errorf("empty backup file %s: %w", backupFileName, err)
return nil, err
}
if err := fileutils.WriteRename(origFileName, bakData); err != nil {
err = fmt.Errorf("failed to overwrite %s with backup data: %w", origFileName, err)
return nil, err
}
return bakData, nil
}
// Start start publishing on the socket
func (s *Publisher) Start() error {
// we only do this for not publishing to dir, and publishing to socket
// which already was indicated by having the listener set up
if s.listener == nil {
return nil
}
s.log.Functionf("Creating %s at %s", "func", logutils.GetMyStack())
go func(s *Publisher) {
instance := 0
done := false
for !done {
if areWeDone(s.log, s.doneChan) {
done = true
continue
}
// We interrupt this accept by closing s.listener
// when we close s.doneChan
c, err := s.listener.Accept()
if err != nil {
s.log.Errorf("publisher(%s) failed %s\n", s.name, err)
// Assume error and bail
done = true
continue
}
s.log.Functionf("Creating %s at %s", "s.serveConnection", logutils.GetMyStack())
go s.serveConnection(c, instance)
maybeLogAllocated(s.log)
instance++
}
s.log.Warnf("Start(%s) acceptor goroutine exiting", s.name)
}(s)
return nil
}
// Stop the publisher
func (s *Publisher) Stop() error {
s.log.Functionf("Stop(%s)", s.name)
if s.listener == nil {
// Nothing to do
return nil
}
close(s.doneChan)
// Trigger any goroutine blocked in Accept to wake up and exit
s.listener.Close()
return nil
}
// Restart indicate that the topic is restarted if counter is non-zero
func (s *Publisher) Restart(restartCounter int) error {
restartFile := s.dirName + "/" + "restarted"
if restartCounter != 0 {
str := strconv.Itoa(restartCounter)
cb := []byte(str)
err := fileutils.WriteRename(restartFile, cb)
if err != nil {
errStr := fmt.Sprintf("pub.restartImpl(%s): openfile failed %s", s.name, err)
return errors.New(errStr)
}
} else {
if err := os.Remove(restartFile); err != nil {
errStr := fmt.Sprintf("pub.restartImpl(%s): remove failed %s", s.name, err)
return errors.New(errStr)
}
}
return nil
}
// LargeDirName where to put large fields
func (s *Publisher) LargeDirName() string {
return fmt.Sprintf("%s/persist/pubsub-large", s.rootDir)
}
func (s *Publisher) serveConnection(conn net.Conn, instance int) {
s.log.Functionf("serveConnection(%s/%d)\n", s.name, instance)
defer conn.Close()
// Track the set of keys/values we are sending to the peer
sendToPeer := make(pubsub.LocalCollection)
sentRestartCounter := 0
// Small buffer since we only read "request <topic>"
buf := make([]byte, 256)
// Read request
res, err := conn.Read(buf)
if err != nil {
// Peer process could have died
s.log.Errorf("serveConnection(%s/%d) error: %v", s.name, instance, err)
return
}
if res == len(buf) {
// Likely truncated
// Peer process could have died
s.log.Errorf("serveConnection(%s/%d) request likely truncated\n", s.name, instance)
return
}
request := strings.Split(string(buf[0:res]), " ")
s.log.Functionf("serveConnection read %d: %v\n", len(request), request)
if len(request) != 2 || request[0] != "request" || request[1] != s.topic {
s.log.Errorf("Invalid request message: %v\n", request)
return
}
_, err = conn.Write([]byte(fmt.Sprintf("hello %s", s.topic)))
if err != nil {
s.log.Errorf("serveConnection(%s/%d) failed %s\n", s.name, instance, err)
return
}
// Insert our notification channel before we get the initial
// snapshot to avoid missing any updates/deletes.
updater := make(chan pubsub.Notify, 1)
s.updaters.Add(s.log, updater, s.name, instance)
defer s.updaters.Remove(s.log, updater)
// Get a local snapshot of the collection and the set of keys
// we need to send these. Updates the local collection.
keys := s.differ.DetermineDiffs(sendToPeer)
// Send the keys we just determined; all since this is the initial
err = s.serialize(conn, keys, sendToPeer)
if err != nil {
s.log.Errorf("serveConnection(%s/%d) serialize failed %s\n", s.name, instance, err)
return
}
err = s.sendComplete(conn)
if err != nil {
s.log.Errorf("serveConnection(%s/%d) sendComplete failed %s\n", s.name, instance, err)
return
}
if s.restarted.RestartCounter() != sentRestartCounter {
err = s.sendRestarted(conn, s.restarted.RestartCounter())
if err != nil {
s.log.Errorf("serveConnection(%s/%d) sendRestarted failed %s\n", s.name, instance, err)
return
}
sentRestartCounter = s.restarted.RestartCounter()
}
// Handle any changes
done := false
for !done {
s.log.Tracef("serveConnection(%s/%d) waiting for notification\n", s.name, instance)
startWait := time.Now()
select {
case _, ok := <-s.doneChan:
if !ok {
done = true
continue
} else {
s.log.Fatal("Received message on doneChan")
}
case <-updater:
}
waitTime := time.Since(startWait)
s.log.Tracef("serveConnection(%s/%d) received notification waited %d seconds\n", s.name, instance, waitTime/time.Second)
// Grab any change to restartCounter before we determine diffs
newRestartCounter := s.restarted.RestartCounter()
// Update and determine which keys changed
keys := s.differ.DetermineDiffs(sendToPeer)
// Send the updates and deletes for those keys
err = s.serialize(conn, keys, sendToPeer)
if err != nil {
s.log.Errorf("serveConnection(%s/%d) serialize failed %s\n", s.name, instance, err)
return
}
if newRestartCounter != sentRestartCounter {
err = s.sendRestarted(conn, newRestartCounter)
if err != nil {
s.log.Errorf("serveConnection(%s/%d) sendRestarted failed %s\n", s.name, instance, err)
return
}
sentRestartCounter = newRestartCounter
}
}
s.log.Warnf("serveConnection(%s) goroutine exiting", s.name)
}
func (s *Publisher) serialize(sock net.Conn, keys []string,
sendToPeer pubsub.LocalCollection) error {
s.log.Tracef("serialize(%s, %v)\n", s.name, keys)
for _, key := range keys {
val, ok := sendToPeer[key]
if ok {
err := s.sendUpdate(sock, key, val)
if err != nil {
s.log.Errorf("serialize(%s) sendUpdate failed %s\n", s.name, err)
return err
}
} else {
err := s.sendDelete(sock, key)
if err != nil {
s.log.Errorf("serialize(%s) sendDelete failed %s\n", s.name, err)
return err
}
}
}
return nil
}
func (s *Publisher) sendUpdate(sock net.Conn, key string,
val []byte) error {
s.log.Tracef("sendUpdate(%s): key %s\n", s.name, key)
// base64-encode to avoid having spaces in the key and val
sendKey := base64.StdEncoding.EncodeToString([]byte(key))
sendVal := base64.StdEncoding.EncodeToString(val)
buf := fmt.Sprintf("update %s %s %s", s.topic, sendKey, sendVal)
if len(buf) >= maxsize {
s.log.Fatalf("Too large message (%d bytes) sent to %s topic %s key %s",
len(buf), s.name, s.topic, key)
}
_, err := sock.Write([]byte(buf))
return err
}
func (s *Publisher) sendDelete(sock net.Conn, key string) error {
s.log.Tracef("sendDelete(%s): key %s\n", s.name, key)
// base64-encode to avoid having spaces in the key
sendKey := base64.StdEncoding.EncodeToString([]byte(key))
buf := fmt.Sprintf("delete %s %s", s.topic, sendKey)
if len(buf) >= maxsize {
s.log.Fatalf("Too large message (%d bytes) sent to %s topic %s key %s",
len(buf), s.name, s.topic, key)
}
_, err := sock.Write([]byte(buf))
return err
}
func (s *Publisher) sendRestarted(sock net.Conn, restartCounter int) error {
s.log.Functionf("sendRestarted(%s)\n", s.name)
buf := fmt.Sprintf("restarted %s %d", s.topic, restartCounter)
if len(buf) >= maxsize {
s.log.Fatalf("Too large message (%d bytes) sent to %s topic %s",
len(buf), s.name, s.topic)
}
_, err := sock.Write([]byte(buf))
return err
}
func (s *Publisher) sendComplete(sock net.Conn) error {
s.log.Functionf("sendComplete(%s)\n", s.name)
buf := fmt.Sprintf("complete %s", s.topic)
if len(buf) >= maxsize {
s.log.Fatalf("Too large message (%d bytes) sent to %s topic %s",
len(buf), s.name, s.topic)
}
_, err := sock.Write([]byte(buf))
return err
}
// CheckMaxSize returns an error if too large
func (s *Publisher) CheckMaxSize(key string, val []byte) error {
s.log.Tracef("CheckMaxSize(%s): key %s\n", s.name, key)
// base64-encode to avoid having spaces in the key and val
sendKey := base64.StdEncoding.EncodeToString([]byte(key))
sendVal := base64.StdEncoding.EncodeToString(val)
buf := fmt.Sprintf("update %s %s %s", s.topic, sendKey, sendVal)
if len(buf) >= maxsize {
return fmt.Errorf("key %s serialized to size %d exceeds max %d",
key, len(buf), maxsize)
}
return nil
}