Issue #213: Make sure we wait for configuration to be saved

There might be a case where the program is terminated before
configuration is saved.

Also, avoid calling save() multiple times on shutdowns.

License: MIT
Signed-off-by: Hector Sanjuan <hector@protocol.ai>

cluster.go

@@ -424,7 +424,6 @@ func (c *Cluster) Shutdown() error {
 			time.Sleep(2 * time.Second)
 		}
 		c.config.Bootstrap = c.peerManager.peersAddrs()
-		c.config.NotifySave()
 		c.peerManager.resetPeers()
 	}
 

config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -67,6 +68,9 @@ type jsonSection map[string]*json.RawMessage
 // central configuration file when doing LoadJSON(), and saved to it
 // when doing SaveJSON().
 type Manager struct {
+	ctx    context.Context
+	cancel func()
+	wg     sync.WaitGroup
 
 	// The Cluster configuration has a top-level
 	// special section.
@@ -87,17 +91,31 @@ type Manager struct {
 // NewManager returns a correctly initialized Manager
 // which is ready to accept component configurations.
 func NewManager() *Manager {
+	ctx, cancel := context.WithCancel(context.Background())
 	return &Manager{
+		ctx:      ctx,
+		cancel:   cancel,
 		sections: make(map[SectionType]Section),
 	}
 
 }
 
+func (cfg *Manager) Shutdown() {
+	cfg.cancel()
+	cfg.wg.Wait()
+}
+
 func (cfg *Manager) watchSave(save <-chan struct{}) {
+	defer cfg.wg.Done()
 	for {
 		select {
 		case <-save:
-			cfg.SaveJSON("")
+			err := cfg.SaveJSON("")
+			if err != nil {
+				logger.Error(err)
+			}
+		case <-cfg.ctx.Done():
+			return
 		}
 	}
 }
@@ -141,6 +159,7 @@ func (cfg *Manager) Default() error {
 
 // RegisterComponent lets the Manager load and save component configurations
 func (cfg *Manager) RegisterComponent(t SectionType, ccfg ComponentConfig) {
+	cfg.wg.Add(1)
 	go cfg.watchSave(ccfg.SaveCh())
 
 	if t == Cluster {
@@ -278,8 +297,7 @@ func (cfg *Manager) SaveJSON(path string) error {
 		return err
 	}
 
-	err = ioutil.WriteFile(path, bs, 0600)
-	return err
+	return ioutil.WriteFile(path, bs, 0600)
 }
 
 // ToJSON provides a JSON representation of the configuration by
@@ -297,6 +315,7 @@ func (cfg *Manager) ToJSON() ([]byte, error) {
 
 	if cfg.clusterConfig != nil {
 		raw, err := cfg.clusterConfig.ToJSON()
+
 		if err != nil {
 			return nil, err
 		}

ipfs-cluster-service/main.go

@@ -317,6 +317,7 @@ func daemon(c *cli.Context) error {
 		case <-signalChan:
 			err = cluster.Shutdown()
 			checkErr("shutting down cluster", err)
+			cfg.Shutdown()
 		case <-cluster.Done():
 			return nil
 

peer_manager.go

@@ -67,7 +67,6 @@ func (pm *peerManager) rmPeer(pid peer.ID, selfShutdown bool) error {
 				time.Sleep(1 * time.Second)
 				pm.cluster.consensus.Shutdown()
 				pm.cluster.config.Bootstrap = pm.peersAddrs()
-				pm.cluster.config.NotifySave()
 				pm.resetPeers()
 				time.Sleep(4 * time.Second)
 				pm.cluster.Shutdown()
@@ -79,7 +78,9 @@ func (pm *peerManager) rmPeer(pid peer.ID, selfShutdown bool) error {
 }
 
 func (pm *peerManager) savePeers() {
-	pm.cluster.config.Peers = pm.peersAddrs()
+	peers := pm.peersAddrs()
+	logger.Debugf("saving peers: %s", peers)
+	pm.cluster.config.Peers = peers
 	pm.cluster.config.NotifySave()
 }