Add encoding stdlib interfaces

exp/lighthorizon/index/trie.go

@@ -2,6 +2,7 @@ package index
 
 import (
  "bufio"
+ "encoding"
  "io"
  "sync"
 
@@ -224,20 +225,48 @@ func (i *TrieIndex) Merge(other *TrieIndex) error {
  return nil
 }
 
-func (i *TrieIndex) ReadFrom(r io.Reader) (int64, error) {
- i.Lock()
- defer i.Unlock()
+func (i *TrieIndex) MarshalBinary() ([]byte, error) {
+ i.RLock()
+ defer i.RUnlock()
 
- br := bufio.NewReader(r)
- bytes, err := io.ReadAll(br)
+ xdrRoot := xdr.TrieNode{}
+
+ // Apparently this is possible?
+ if i.Root != nil {
+ xdrRoot.Prefix = i.Root.Prefix
+ xdrRoot.Value = i.Root.Value
+ xdrRoot.Children = make([]xdr.TrieNodeChild, 0, len(i.Root.Children))
+
+ for key, node := range i.Root.Children {
+ buildXdrTrie(key, node, &xdrRoot)
+ }
+ }
+
+ xdrIndex := xdr.TrieIndex{Version: TrieIndexVersion, Root: xdrRoot}
+ return xdrIndex.MarshalBinary()
+}
+
+func (i *TrieIndex) WriteTo(w io.Writer) (int64, error) {
+ i.RLock()
+ defer i.RUnlock()
+
+ bytes, err := i.MarshalBinary()
  if err != nil {
  return int64(len(bytes)), err
  }
 
+ count, err := w.Write(bytes)
+ return int64(count), err
+}
+
+func (i *TrieIndex) UnmarshalBinary(bytes []byte) error {
+ i.RLock()
+ defer i.RUnlock()
+
  xdrIndex := xdr.TrieIndex{}
- err = xdrIndex.UnmarshalBinary(bytes)
+ err := xdrIndex.UnmarshalBinary(bytes)
  if err != nil {
- return int64(len(bytes)), err
+ return err
  }
 
  i.Root = &trieNode{
@@ -250,9 +279,28 @@ func (i *TrieIndex) ReadFrom(r io.Reader) (int64, error) {
  buildTrie(&node, i.Root)
  }
 
- return int64(len(bytes)), nil
+ return nil
 }
 
+func (i *TrieIndex) ReadFrom(r io.Reader) (int64, error) {
+ i.RLock()
+ defer i.RUnlock()
+
+ br := bufio.NewReader(r)
+ bytes, err := io.ReadAll(br)
+ if err != nil {
+ return int64(len(bytes)), err
+ }
+
+ return int64(len(bytes)), i.UnmarshalBinary(bytes)
+}
+
+// buildTrie recursively builds the equivalent `TrieNode` structure from raw
+// XDR, creating the key->value child mapping from the flat list of children.
+// Here, `xdrNode` is the node we're processing and `parent` is its non-XDR
+// parent (i.e. the parent was already converted from XDR).
+//
+// This is the opposite of buildXdrTrie.
 func buildTrie(xdrNode *xdr.TrieNodeChild, parent *trieNode) {
  node := &trieNode{
  Prefix: xdrNode.Node.Prefix,
@@ -266,36 +314,12 @@ func buildTrie(xdrNode *xdr.TrieNodeChild, parent *trieNode) {
  }
 }
 
-func (i *TrieIndex) WriteTo(w io.Writer) (int64, error) {
- i.RLock()
- defer i.RUnlock()
-
- xdrRoot := xdr.TrieNode{}
-
- // Apparently this is possible?
- if i.Root != nil {
- xdrRoot.Prefix = i.Root.Prefix
- xdrRoot.Value = i.Root.Value
- xdrRoot.Children = make([]xdr.TrieNodeChild, 0, len(i.Root.Children))
-
- for key, node := range i.Root.Children {
- buildXdrTrie(key, node, &xdrRoot)
- }
- }
-
- xdrIndex := xdr.TrieIndex{Version: TrieIndexVersion, Root: xdrRoot}
- bytes, err := xdrIndex.MarshalBinary()
- if err != nil {
- return int64(len(bytes)), err
- }
-
- count, err := w.Write(bytes)
- return int64(count), err
-}
-
-// Recursively builds the XDR-equivalent Trie structure, where `i` is the node
-// we're converting and `parent` is the already-converted parent. That is, the
-// non-XDR version of `parent` should have had (`key`, `i`) as a child.
+// buildXdrTrie recursively builds the XDR-equivalent TrieNode structure, where
+// `i` is the node we're converting and `parent` is the already-converted
+// parent. That is, the non-XDR version of `parent` should have had (`key`, `i`)
+// as a child.
+//
+// This is the opposite of buildTrie.
 func buildXdrTrie(key byte, node *trieNode, parent *xdr.TrieNode) {
  self := xdr.TrieNode{
  Prefix: node.Prefix,
@@ -316,3 +340,6 @@ func buildXdrTrie(key byte, node *trieNode, parent *xdr.TrieNode) {
 // Ensure we're compatible with stdlib interfaces.
 var _ io.WriterTo = &TrieIndex{}
 var _ io.ReaderFrom = &TrieIndex{}
+
+var _ encoding.BinaryMarshaler = &TrieIndex{}
+var _ encoding.BinaryUnmarshaler = &TrieIndex{}

exp/lighthorizon/index/xdr/xdr_generated.go

@@ -14,7 +14,7 @@ import (
  "fmt"
  "io"
 
- "github.com/stellar/go-xdr/xdr3"
+ xdr "github.com/stellar/go-xdr/xdr3"
 )
 
 type xdrType interface {