Merge pull request #5611 from ipfs/features/streaming-ls-5600

Add --stream option to `ls` command

Author: Stebalien

core/commands/ls.go

@@ -1,13 +1,12 @@
 package commands
 
 import (
-	"bytes"
 	"fmt"
 	"io"
+	"os"
 	"text/tabwriter"
 
-	cmds "github.com/ipfs/go-ipfs/commands"
-	e "github.com/ipfs/go-ipfs/core/commands/e"
+	cmdenv "github.com/ipfs/go-ipfs/core/commands/cmdenv"
 	iface "github.com/ipfs/go-ipfs/core/coreapi/interface"
 
 	cid "gx/ipfs/QmR8BauakNcBa3RbE4nbQu76PDiJgoQgz8AJdhJuiU4TAw/go-cid"
@@ -16,29 +15,36 @@ import (
 	unixfspb "gx/ipfs/QmUnHNqhSB1JgzVCxL1Kz3yb4bdyB4q1Z9AD5AUBVmt3fZ/go-unixfs/pb"
 	blockservice "gx/ipfs/QmVDTbzzTwnuBwNbJdhW3u7LoBQp46bezm9yp4z1RoEepM/go-blockservice"
 	offline "gx/ipfs/QmYZwey1thDTynSrvd6qQkX24UpTka6TFhQ2v569UpoqxD/go-ipfs-exchange-offline"
+	cmds "gx/ipfs/Qma6uuSyjkecGhMFFLfzyJDPyoDtNJSHJNweDccZhaWkgU/go-ipfs-cmds"
 	merkledag "gx/ipfs/QmcGt25mrjuB2kKW2zhPbXVZNHc4yoTDQ65NA8m6auP2f1/go-merkledag"
 	ipld "gx/ipfs/QmcKKBwfz6FyQdHR2jsXrrF6XeSBXYL86anmWNewpFpoF5/go-ipld-format"
 	"gx/ipfs/Qmde5VP1qUkyQXKCfmEUA7bP64V2HAptbJ7phuPp7jXWwg/go-ipfs-cmdkit"
 )
 
+// LsLink contains printable data for a single ipld link in ls output
 type LsLink struct {
 	Name, Hash string
 	Size       uint64
 	Type       unixfspb.Data_DataType
 }
 
+// LsObject is an element of LsOutput
+// It can represent all or part of a directory
 type LsObject struct {
 	Hash  string
 	Links []LsLink
 }
 
+// LsOutput is a set of printable data for directories,
+// it can be complete or partial
 type LsOutput struct {
 	Objects []LsObject
 }
 
 const (
 	lsHeadersOptionNameTime = "headers"
 	lsResolveTypeOptionName = "resolve-type"
+	lsStreamOptionName      = "stream"
 )
 
 var LsCmd = &cmds.Command{
@@ -60,158 +66,235 @@ The JSON output contains type information.
 	Options: []cmdkit.Option{
 		cmdkit.BoolOption(lsHeadersOptionNameTime, "v", "Print table headers (Hash, Size, Name)."),
 		cmdkit.BoolOption(lsResolveTypeOptionName, "Resolve linked objects to find out their types.").WithDefault(true),
+		cmdkit.BoolOption(lsStreamOptionName, "s", "Enable exprimental streaming of directory entries as they are traversed."),
 	},
-	Run: func(req cmds.Request, res cmds.Response) {
-		nd, err := req.InvocContext().GetNode()
+	Run: func(req *cmds.Request, res cmds.ResponseEmitter, env cmds.Environment) error {
+		nd, err := cmdenv.GetNode(env)
 		if err != nil {
-			res.SetError(err, cmdkit.ErrNormal)
-			return
+			return err
 		}
 
-		api, err := req.InvocContext().GetApi()
+		api, err := cmdenv.GetApi(env)
 		if err != nil {
-			res.SetError(err, cmdkit.ErrNormal)
-			return
-		}
-
-		// get options early -> exit early in case of error
-		if _, _, err := req.Option(lsHeadersOptionNameTime).Bool(); err != nil {
-			res.SetError(err, cmdkit.ErrNormal)
-			return
-		}
-
-		resolve, _, err := req.Option(lsResolveTypeOptionName).Bool()
-		if err != nil {
-			res.SetError(err, cmdkit.ErrNormal)
-			return
+			return err
 		}
 
+		resolve, _ := req.Options[lsResolveTypeOptionName].(bool)
 		dserv := nd.DAG
 		if !resolve {
 			offlineexch := offline.Exchange(nd.Blockstore)
 			bserv := blockservice.New(nd.Blockstore, offlineexch)
 			dserv = merkledag.NewDAGService(bserv)
 		}
 
-		paths := req.Arguments()
+		err = req.ParseBodyArgs()
+		if err != nil {
+			return err
+		}
+
+		paths := req.Arguments
 
 		var dagnodes []ipld.Node
 		for _, fpath := range paths {
 			p, err := iface.ParsePath(fpath)
 			if err != nil {
-				res.SetError(err, cmdkit.ErrNormal)
-				return
+				return err
 			}
-
-			dagnode, err := api.ResolveNode(req.Context(), p)
+			dagnode, err := api.ResolveNode(req.Context, p)
 			if err != nil {
-				res.SetError(err, cmdkit.ErrNormal)
-				return
+				return err
 			}
 			dagnodes = append(dagnodes, dagnode)
 		}
-
-		output := make([]LsObject, len(req.Arguments()))
-		ng := merkledag.NewSession(req.Context(), nd.DAG)
+		ng := merkledag.NewSession(req.Context, nd.DAG)
 		ro := merkledag.NewReadOnlyDagService(ng)
 
+		stream, _ := req.Options[lsStreamOptionName].(bool)
+
+		if !stream {
+			output := make([]LsObject, len(req.Arguments))
+
+			for i, dagnode := range dagnodes {
+				dir, err := uio.NewDirectoryFromNode(ro, dagnode)
+				if err != nil && err != uio.ErrNotADir {
+					return fmt.Errorf("the data in %s (at %q) is not a UnixFS directory: %s", dagnode.Cid(), paths[i], err)
+				}
+
+				var links []*ipld.Link
+				if dir == nil {
+					links = dagnode.Links()
+				} else {
+					links, err = dir.Links(req.Context)
+					if err != nil {
+						return err
+					}
+				}
+				outputLinks := make([]LsLink, len(links))
+				for j, link := range links {
+					lsLink, err := makeLsLink(req, dserv, resolve, link)
+					if err != nil {
+						return err
+					}
+					outputLinks[j] = *lsLink
+				}
+				output[i] = LsObject{
+					Hash:  paths[i],
+					Links: outputLinks,
+				}
+			}
+
+			return cmds.EmitOnce(res, &LsOutput{output})
+		}
+
 		for i, dagnode := range dagnodes {
 			dir, err := uio.NewDirectoryFromNode(ro, dagnode)
 			if err != nil && err != uio.ErrNotADir {
-				res.SetError(fmt.Errorf("the data in %s (at %q) is not a UnixFS directory: %s", dagnode.Cid(), paths[i], err), cmdkit.ErrNormal)
-				return
+				return fmt.Errorf("the data in %s (at %q) is not a UnixFS directory: %s", dagnode.Cid(), paths[i], err)
 			}
 
-			var links []*ipld.Link
+			var linkResults <-chan unixfs.LinkResult
 			if dir == nil {
-				links = dagnode.Links()
+				linkResults = makeDagNodeLinkResults(req, dagnode)
 			} else {
-				links, err = dir.Links(req.Context())
-				if err != nil {
-					res.SetError(err, cmdkit.ErrNormal)
-					return
-				}
-			}
-
-			output[i] = LsObject{
-				Hash:  paths[i],
-				Links: make([]LsLink, len(links)),
+				linkResults = dir.EnumLinksAsync(req.Context)
 			}
 
-			for j, link := range links {
-				t := unixfspb.Data_DataType(-1)
-
-				switch link.Cid.Type() {
-				case cid.Raw:
-					// No need to check with raw leaves
-					t = unixfs.TFile
-				case cid.DagProtobuf:
-					linkNode, err := link.GetNode(req.Context(), dserv)
-					if err == ipld.ErrNotFound && !resolve {
-						// not an error
-						linkNode = nil
-					} else if err != nil {
-						res.SetError(err, cmdkit.ErrNormal)
-						return
-					}
+			for linkResult := range linkResults {
 
-					if pn, ok := linkNode.(*merkledag.ProtoNode); ok {
-						d, err := unixfs.FSNodeFromBytes(pn.Data())
-						if err != nil {
-							res.SetError(err, cmdkit.ErrNormal)
-							return
-						}
-						t = d.Type()
-					}
+				if linkResult.Err != nil {
+					return linkResult.Err
+				}
+				link := linkResult.Link
+				lsLink, err := makeLsLink(req, dserv, resolve, link)
+				if err != nil {
+					return err
 				}
-				output[i].Links[j] = LsLink{
-					Name: link.Name,
-					Hash: link.Cid.String(),
-					Size: link.Size,
-					Type: t,
+				output := []LsObject{{
+					Hash:  paths[i],
+					Links: []LsLink{*lsLink},
+				}}
+				if err = res.Emit(&LsOutput{output}); err != nil {
+					return err
 				}
 			}
 		}
+		return nil
+	},
+	PostRun: cmds.PostRunMap{
+		cmds.CLI: func(res cmds.Response, re cmds.ResponseEmitter) error {
+			req := res.Request()
+			lastObjectHash := ""
 
-		res.SetOutput(&LsOutput{output})
+			for {
+				v, err := res.Next()
+				if err != nil {
+					if err == io.EOF {
+						return nil
+					}
+					return err
+				}
+				out := v.(*LsOutput)
+				lastObjectHash = tabularOutput(req, os.Stdout, out, lastObjectHash, false)
+			}
+		},
+	},
+	Encoders: cmds.EncoderMap{
+		cmds.Text: cmds.MakeTypedEncoder(func(req *cmds.Request, w io.Writer, out *LsOutput) error {
+			// when streaming over HTTP using a text encoder, we cannot render breaks
+			// between directories because we don't know the hash of the last
+			// directory encoder
+			ignoreBreaks, _ := req.Options[lsStreamOptionName].(bool)
+			tabularOutput(req, w, out, "", ignoreBreaks)
+			return nil
+		}),
 	},
-	Marshalers: cmds.MarshalerMap{
-		cmds.Text: func(res cmds.Response) (io.Reader, error) {
+	Type: LsOutput{},
+}
 
-			v, err := unwrapOutput(res.Output())
+func makeDagNodeLinkResults(req *cmds.Request, dagnode ipld.Node) <-chan unixfs.LinkResult {
+	links := dagnode.Links()
+	linkResults := make(chan unixfs.LinkResult, len(links))
+	defer close(linkResults)
+	for _, l := range links {
+		linkResults <- unixfs.LinkResult{
+			Link: l,
+			Err:  nil,
+		}
+	}
+	return linkResults
+}
+
+func makeLsLink(req *cmds.Request, dserv ipld.DAGService, resolve bool, link *ipld.Link) (*LsLink, error) {
+	t := unixfspb.Data_DataType(-1)
+
+	switch link.Cid.Type() {
+	case cid.Raw:
+		// No need to check with raw leaves
+		t = unixfs.TFile
+	case cid.DagProtobuf:
+		linkNode, err := link.GetNode(req.Context, dserv)
+		if err == ipld.ErrNotFound && !resolve {
+			// not an error
+			linkNode = nil
+		} else if err != nil {
+			return nil, err
+		}
+
+		if pn, ok := linkNode.(*merkledag.ProtoNode); ok {
+			d, err := unixfs.FSNodeFromBytes(pn.Data())
 			if err != nil {
 				return nil, err
 			}
+			t = d.Type()
+		}
+	}
+	return &LsLink{
+		Name: link.Name,
+		Hash: link.Cid.String(),
+		Size: link.Size,
+		Type: t,
+	}, nil
+}
 
-			headers, _, _ := res.Request().Option(lsHeadersOptionNameTime).Bool()
-			output, ok := v.(*LsOutput)
-			if !ok {
-				return nil, e.TypeErr(output, v)
-			}
+func tabularOutput(req *cmds.Request, w io.Writer, out *LsOutput, lastObjectHash string, ignoreBreaks bool) string {
+	headers, _ := req.Options[lsHeadersOptionNameTime].(bool)
+	stream, _ := req.Options[lsStreamOptionName].(bool)
+	// in streaming mode we can't automatically align the tabs
+	// so we take a best guess
+	var minTabWidth int
+	if stream {
+		minTabWidth = 10
+	} else {
+		minTabWidth = 1
+	}
 
-			buf := new(bytes.Buffer)
-			w := tabwriter.NewWriter(buf, 1, 2, 1, ' ', 0)
-			for _, object := range output.Objects {
-				if len(output.Objects) > 1 {
-					fmt.Fprintf(w, "%s:\n", object.Hash)
-				}
-				if headers {
-					fmt.Fprintln(w, "Hash\tSize\tName")
-				}
-				for _, link := range object.Links {
-					if link.Type == unixfs.TDirectory {
-						link.Name += "/"
-					}
-					fmt.Fprintf(w, "%s\t%v\t%s\n", link.Hash, link.Size, link.Name)
-				}
-				if len(output.Objects) > 1 {
-					fmt.Fprintln(w)
+	multipleFolders := len(req.Arguments) > 1
+
+	tw := tabwriter.NewWriter(w, minTabWidth, 2, 1, ' ', 0)
+
+	for _, object := range out.Objects {
+
+		if !ignoreBreaks && object.Hash != lastObjectHash {
+			if multipleFolders {
+				if lastObjectHash != "" {
+					fmt.Fprintln(tw)
 				}
+				fmt.Fprintf(tw, "%s:\n", object.Hash)
 			}
-			w.Flush()
+			if headers {
+				fmt.Fprintln(tw, "Hash\tSize\tName")
+			}
+			lastObjectHash = object.Hash
+		}
 
-			return buf, nil
-		},
-	},
-	Type: LsOutput{},
+		for _, link := range object.Links {
+			if link.Type == unixfs.TDirectory {
+				link.Name += "/"
+			}
+
+			fmt.Fprintf(tw, "%s\t%v\t%s\n", link.Hash, link.Size, link.Name)
+		}
+	}
+	tw.Flush()
+	return lastObjectHash
 }