Fixing locking; unlock still not working

litestream.go

@@ -2,7 +2,9 @@ package litestream
 
 import (
 	"encoding/binary"
+	"encoding/hex"
 	"io"
+	"strings"
 )
 
 // Magic number specified at the beginning of WAL files.
@@ -40,3 +42,38 @@ func Checksum(bo binary.ByteOrder, s uint64, b []byte) (_ uint64, err error) {
 	}
 	return uint64(s0)<<32 | uint64(s1), nil
 }
+
+// HexDump returns hexdump output but with duplicate lines removed.
+func HexDump(b []byte) string {
+	const prefixN = len("00000000")
+
+	var output []string
+	var prev string
+	var ellipsis bool
+
+	lines := strings.Split(strings.TrimSpace(hex.Dump(b)), "\n")
+	for i, line := range lines {
+		// Add line to output if it is not repeating or the last line.
+		if i == 0 || i == len(lines)-1 || trimPrefixN(line, prefixN) != trimPrefixN(prev, prefixN) {
+			output = append(output, line)
+			prev, ellipsis = line, false
+			continue
+		}
+
+		// Add an ellipsis for the first duplicate line.
+		if !ellipsis {
+			output = append(output, "...")
+			ellipsis = true
+			continue
+		}
+	}
+
+	return strings.Join(output, "\n")
+}
+
+func trimPrefixN(s string, n int) string {
+	if len(s) < n {
+		return ""
+	}
+	return s[n:]
+}