Merge pull request #52 from ipfs/rvagg/nopreload-byte-ranges

feat: add entity matcher w/o preload, add matcher fn for consuming bytes

Author: hannahhoward

signaling.go

@@ -1,10 +1,13 @@
 package unixfsnode
 
 import (
+	"io"
+
 	"github.com/ipld/go-ipld-prime"
 	"github.com/ipld/go-ipld-prime/datamodel"
 	"github.com/ipld/go-ipld-prime/linking"
 	"github.com/ipld/go-ipld-prime/node/basicnode"
+	"github.com/ipld/go-ipld-prime/traversal"
 	"github.com/ipld/go-ipld-prime/traversal/selector"
 	"github.com/ipld/go-ipld-prime/traversal/selector/builder"
 )
@@ -26,10 +29,30 @@ var ExploreAllRecursivelySelector = specBuilder(func(ssb builder.SelectorSpecBui
 // not, but not its contents.
 // MatchUnixfsPreloadSelector is precompiled for use with
 // UnixFSPathSelectorBuilder().
+//
+// NOTE: This selector may be deprecated in a future release. Users should
+// instead use MatchUnixFSEntitySelector instead, which is intended to have the
+// same effect but doesn't use the "unixfs-preload" ADL.
 var MatchUnixFSPreloadSelector = specBuilder(func(ssb builder.SelectorSpecBuilder) builder.SelectorSpec {
 	return ssb.ExploreInterpretAs("unixfs-preload", ssb.Matcher())
 })
 
+// MatchUnixFSEntitySelector is a selector that will match a single node and its
+// direct children.
+//
+// For UnixFS files, this will match the file and its blocks.
+//
+// For UnixFS directories, and will iterate through the list of child links but
+// will not iterate _into_ the child directories.
+var MatchUnixFSEntitySelector = specBuilder(func(ssb builder.SelectorSpecBuilder) builder.SelectorSpec {
+	return ssb.ExploreInterpretAs("unixfs", ssb.ExploreUnion(ssb.Matcher(),
+		ssb.ExploreRecursive(
+			selector.RecursionLimitDepth(1),
+			ssb.ExploreAll(ssb.ExploreRecursiveEdge()),
+		),
+	))
+})
+
 // MatchUnixFSSelector is a selector that will match a single node, similar to
 // selectorparse.CommonSelector_MatchPoint, but uses the "unixfs" ADL to load
 // as UnixFS data. Unlike MatchUnixFSPreloadSelector, this selector will not
@@ -40,6 +63,26 @@ var MatchUnixFSSelector = specBuilder(func(ssb builder.SelectorSpecBuilder) buil
 	return ssb.ExploreInterpretAs("unixfs", ssb.Matcher())
 })
 
+// BytesConsumingMatcher is a traversal.WalkMatching matcher function that
+// consumes the bytes of a LargeBytesNode where one is matched. Use this in
+// conjunction with the Match* selectors in this package to ensure that all
+// blocks of sharded files are loaded during a traversal, or that the subset
+// of blocks required to fulful a range selector are loaded.
+func BytesConsumingMatcher(p traversal.Progress, n datamodel.Node) error {
+	if lbn, ok := n.(datamodel.LargeBytesNode); ok {
+		rdr, err := lbn.AsLargeBytes()
+		if err != nil {
+			return err
+		}
+		_, err = io.Copy(io.Discard, rdr)
+		return err
+	}
+	return nil
+}
+
+// AddUnixFSReificationToLinkSystem will add both unixfs and unixfs-preload
+// reifiers to a LinkSystem. This is primarily useful for traversals that use
+// an interpretAs clause, such as Match* selectors in this package.
 func AddUnixFSReificationToLinkSystem(lsys *ipld.LinkSystem) {
 	if lsys.KnownReifiers == nil {
 		lsys.KnownReifiers = make(map[string]linking.NodeReifier)

signalling_test.go

@@ -22,6 +22,9 @@ var exploreAllJson = mustDagJson(selectorparse.CommonSelector_ExploreAllRecursiv
 // explore interpret-as (~), next (>), match (.), interpreted as unixfs-preload
 var matchUnixfsPreloadJson = `{"~":{">":{".":{}},"as":"unixfs-preload"}}`
 
+// explore interpret-as (~), next (>), union (|) of match (.) and explore recursive (R) edge (@) with a depth of 1, interpreted as unixfs
+var matchUnixfsEntityJson = `{"~":{">":{"|":[{".":{}},{"R":{":>":{"a":{">":{"@":{}}}},"l":{"depth":1}}}]},"as":"unixfs"}}`
+
 // match interpret-as (~), next (>), match (.), interpreted as unixfs
 var matchUnixfsJson = `{"~":{">":{".":{}},"as":"unixfs"}}`
 
@@ -93,11 +96,17 @@ func TestUnixFSPathSelectorBuilder(t *testing.T) {
 			expextedSelector: exploreAllJson,
 		},
 		{
-			name:             "empty path shallow",
+			name:             "empty path shallow (preload)",
 			path:             "",
 			target:           unixfsnode.MatchUnixFSPreloadSelector,
 			expextedSelector: matchUnixfsPreloadJson,
 		},
+		{
+			name:             "empty path shallow (entity)",
+			path:             "",
+			target:           unixfsnode.MatchUnixFSEntitySelector,
+			expextedSelector: matchUnixfsEntityJson,
+		},
 		{
 			name:             "single field",
 			path:             "/foo",
@@ -112,11 +121,17 @@ func TestUnixFSPathSelectorBuilder(t *testing.T) {
 			matchPath:        true,
 		},
 		{
-			name:             "single field shallow",
+			name:             "single field shallow (preload)",
 			path:             "/foo",
 			expextedSelector: jsonFields(matchUnixfsPreloadJson, "foo"),
 			target:           unixfsnode.MatchUnixFSPreloadSelector,
 		},
+		{
+			name:             "single field shallow (entity)",
+			path:             "/foo",
+			expextedSelector: jsonFields(matchUnixfsEntityJson, "foo"),
+			target:           unixfsnode.MatchUnixFSEntitySelector,
+		},
 		{
 			name:             "multiple fields",
 			path:             "/foo/bar",