refactor(core) Close in teardown

This declarative style is simpler to compose than the imperative wiring
up of objects.

+ pass context to StartOnlineServices as parameter. one by one, trying
to remove dependencies on node state so these initialization steps can
be broken down.

Author: Brian Tiger Chow

core/core.go

@@ -2,6 +2,7 @@ package core
 
 import (
 	"fmt"
+	"io"
 
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/code.google.com/p/go.net/context"
 	b58 "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-base58"
@@ -97,11 +98,22 @@ type Mounts struct {
 
 type ConfigOption func(ctx context.Context) (*IpfsNode, error)
 
-func NewIPFSNode(ctx context.Context, option ConfigOption) (*IpfsNode, error) {
+func NewIPFSNode(parent context.Context, option ConfigOption) (*IpfsNode, error) {
+	ctxg := ctxgroup.WithContext(parent)
+	ctx := ctxg.Context()
+	success := false // flip to true after all sub-system inits succeed
+	defer func() {
+		if !success {
+			ctxg.Close()
+		}
+	}()
+
 	node, err := option(ctx)
 	if err != nil {
 		return nil, err
 	}
+	node.ContextGroup = ctxg
+	ctxg.SetTeardown(node.teardown)
 
 	// Need to make sure it's perfectly clear 1) which variables are expected
 	// to be initialized at this point, and 2) which variables will be
@@ -120,6 +132,7 @@ func NewIPFSNode(ctx context.Context, option ConfigOption) (*IpfsNode, error) {
 		node.Pinning = pin.NewPinner(node.Repo.Datastore(), node.DAG)
 	}
 	node.Resolver = &path.Resolver{DAG: node.DAG}
+	success = true
 	return node, nil
 }
 
@@ -135,13 +148,6 @@ func Online(r repo.Repo) ConfigOption {
 func Standard(r repo.Repo, online bool) ConfigOption {
 	return func(ctx context.Context) (n *IpfsNode, err error) {
 
-		success := false // flip to true after all sub-system inits succeed
-		defer func() {
-			if !success && n != nil {
-				n.Close()
-			}
-		}()
-
 		if r == nil {
 			return nil, debugerror.Errorf("repo required")
 		}
@@ -155,9 +161,6 @@ func Standard(r repo.Repo, online bool) ConfigOption {
 			Repo: r,
 		}
 
-		n.ContextGroup = ctxgroup.WithContextAndTeardown(ctx, n.teardown)
-		ctx = n.ContextGroup.Context()
-
 		// setup Peerstore
 		n.Peerstore = peer.NewPeerstore()
 
@@ -173,20 +176,18 @@ func Standard(r repo.Repo, online bool) ConfigOption {
 
 		// setup online services
 		if online {
-			if err := n.StartOnlineServices(); err != nil {
+			if err := n.StartOnlineServices(ctx); err != nil {
 				return nil, err // debugerror.Wraps.
 			}
 		} else {
 			n.Exchange = offline.Exchange(n.Blockstore)
 		}
 
-		success = true
 		return n, nil
 	}
 }
 
-func (n *IpfsNode) StartOnlineServices() error {
-	ctx := n.Context()
+func (n *IpfsNode) StartOnlineServices(ctx context.Context) error {
 
 	if n.PeerHost != nil { // already online.
 		return debugerror.New("node already online")
@@ -197,7 +198,7 @@ func (n *IpfsNode) StartOnlineServices() error {
 		return err
 	}
 
-	peerhost, err := constructPeerHost(ctx, n.ContextGroup, n.Repo.Config(), n.Identity, n.Peerstore)
+	peerhost, err := constructPeerHost(ctx, n.Repo.Config(), n.Identity, n.Peerstore)
 	if err != nil {
 		return debugerror.Wrap(err)
 	}
@@ -207,7 +208,7 @@ func (n *IpfsNode) StartOnlineServices() error {
 	n.Diagnostics = diag.NewDiagnostics(n.Identity, n.PeerHost)
 
 	// setup routing service
-	dhtRouting, err := constructDHTRouting(ctx, n.ContextGroup, n.PeerHost, n.Repo.Datastore())
+	dhtRouting, err := constructDHTRouting(ctx, n.PeerHost, n.Repo.Datastore())
 	if err != nil {
 		return debugerror.Wrap(err)
 	}
@@ -243,9 +244,27 @@ func (n *IpfsNode) StartOnlineServices() error {
 	return nil
 }
 
+// teardown closes children
 func (n *IpfsNode) teardown() error {
-	if err := n.Repo.Close(); err != nil {
-		return err
+	var errs []error
+	closers := []io.Closer{
+		n.Repo,
+	}
+	if n.DHT != nil {
+		closers = append(closers, n.DHT)
+	}
+	if n.PeerHost != nil {
+		closers = append(closers, n.PeerHost)
+	}
+	for _, closer := range closers {
+		if closer != nil {
+			if err := closer.Close(); err != nil {
+				errs = append(errs, err)
+			}
+		}
+	}
+	if len(errs) > 0 {
+		return errs[0]
 	}
 	return nil
 }
@@ -344,7 +363,7 @@ func listenAddresses(cfg *config.Config) ([]ma.Multiaddr, error) {
 }
 
 // isolates the complex initialization steps
-func constructPeerHost(ctx context.Context, ctxg ctxgroup.ContextGroup, cfg *config.Config, id peer.ID, ps peer.Peerstore) (p2phost.Host, error) {
+func constructPeerHost(ctx context.Context, cfg *config.Config, id peer.ID, ps peer.Peerstore) (p2phost.Host, error) {
 	listenAddrs, err := listenAddresses(cfg)
 	if err != nil {
 		return nil, debugerror.Wrap(err)
@@ -362,7 +381,6 @@ func constructPeerHost(ctx context.Context, ctxg ctxgroup.ContextGroup, cfg *con
 	if err != nil {
 		return nil, debugerror.Wrap(err)
 	}
-	ctxg.AddChildGroup(network.CtxGroup())
 
 	peerhost := p2pbhost.New(network)
 	// explicitly set these as our listen addrs.
@@ -377,9 +395,8 @@ func constructPeerHost(ctx context.Context, ctxg ctxgroup.ContextGroup, cfg *con
 	return peerhost, nil
 }
 
-func constructDHTRouting(ctx context.Context, ctxg ctxgroup.ContextGroup, host p2phost.Host, ds datastore.ThreadSafeDatastore) (*dht.IpfsDHT, error) {
+func constructDHTRouting(ctx context.Context, host p2phost.Host, ds datastore.ThreadSafeDatastore) (*dht.IpfsDHT, error) {
 	dhtRouting := dht.NewDHT(ctx, host, ds)
 	dhtRouting.Validators[IpnsValidatorTag] = namesys.ValidateIpnsRecord
-	ctxg.AddChildGroup(dhtRouting)
 	return dhtRouting, nil
 }