Add merge command.

[lightning.git] / tilelib.go

diff --git a/tilelib.go b/tilelib.go
index 857b56683095dc9ddd1c7169fa3b2b1487c0edda..0a8d857cf1226e2d8146c48b64819b549807ec4e 100644 (file)
--- a/tilelib.go
+++ b/tilelib.go
@@ -162,9 +162,25 @@ func (tilelib *tileLibrary) getRef(tag tagID, seq []byte) tileLibRef {
        // if tilelib.seq == nil {
        //      tilelib.seq = map[[blake2b.Size]byte][]byte{}
        // }
-       if tilelib.variant == nil {
+       if tilelib.variant == nil && tilelib.taglib != nil {
                tilelib.variant = make([][][blake2b.Size256]byte, tilelib.taglib.Len())
        }
+       if int(tag) >= len(tilelib.variant) {
+               // If we haven't seen the tag library yet (as in a
+               // merge), tilelib.taglib.Len() is zero. We can still
+               // behave correctly, we just need to expand the
+               // tilelib.variant slice as needed.
+               if int(tag) >= cap(tilelib.variant) {
+                       // Allocate 2x capacity.
+                       newslice := make([][][blake2b.Size256]byte, int(tag)+1, (int(tag)+1)*2)
+                       copy(newslice, tilelib.variant)
+                       tilelib.variant = newslice[:int(tag)+1]
+               } else {
+                       // Use previously allocated capacity, avoiding
+                       // copy.
+                       tilelib.variant = tilelib.variant[:int(tag)+1]
+               }
+       }
        seqhash := blake2b.Sum256(seq)
        for i, varhash := range tilelib.variant[tag] {
                if varhash == seqhash {
@@ -176,7 +192,6 @@ func (tilelib *tileLibrary) getRef(tag tagID, seq []byte) tileLibRef {
        tilelib.variant[tag] = append(tilelib.variant[tag], seqhash)
        // tilelib.seq[seqhash] = append([]byte(nil), seq...)
        variant := tileVariantID(len(tilelib.variant[tag]))
-       ret := tileLibRef{tag: tag, variant: variant}
        tilelib.mtx.Unlock()
 
        if tilelib.encoder != nil {
@@ -189,5 +204,5 @@ func (tilelib *tileLibrary) getRef(tag tagID, seq []byte) tileLibRef {
                        }},
                })
        }
-       return ret
+       return tileLibRef{tag: tag, variant: variant}
 }