initial commit

pkg/fs/chunk.go

@@ -0,0 +1,52 @@
+// Copyright (C) 2022 Marius Schellenberger
+
+package fs
+
+import "sort"
+
+type Chunk [2]int64
+
+type Chunks []Chunk
+
+func (cs Chunks) Len() int           { return len(cs) }
+func (cs Chunks) Less(i, j int) bool { return cs[i][0] < cs[j][0] }
+func (cs Chunks) Swap(i, j int)      { cs[i], cs[j] = cs[j], cs[i] }
+
+func (cs Chunks) Exists(off int64, n int, size int64) bool {
+	end := off + int64(n)
+	if end > size {
+		end = size
+	}
+	for _, c := range cs {
+		if c[0] <= off && c[1] > off && c[1] >= end {
+			return true
+		}
+	}
+	return false
+}
+
+func (cs *Chunks) Add(off int64, n int) {
+	*cs = append(*cs, Chunk{off, off + int64(n)})
+	cs.merge()
+}
+
+func (cs *Chunks) merge() {
+	c := *cs
+	if len(c) < 2 {
+		return
+	}
+	sort.Sort(*cs)
+	for i := 0; i < len(c); i++ {
+		if i+1 == len(c) {
+			break
+		}
+		if c[i][1] >= c[i+1][0] {
+			if c[i+1][1] > c[i][1] {
+				c[i][1] = c[i+1][1]
+			}
+			c = append(c[:i+1], c[i+2:]...)
+			i--
+		}
+	}
+	*cs = c
+}