Initial commit

vendor/github.com/cockroachdb/pebble/internal/manifest/level.go

@@ -0,0 +1,46 @@
+// Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
+// of this source code is governed by a BSD-style license that can be found in
+// the LICENSE file.
+
+package manifest
+
+import "fmt"
+
+const (
+	// 3 bits are necessary to represent level values from 0-6.
+	levelBits = 3
+	levelMask = (1 << levelBits) - 1
+	// invalidSublevel denotes an invalid or non-applicable sublevel.
+	invalidSublevel = -1
+)
+
+// Level encodes a level and optional sublevel for use in log and error
+// messages. The encoding has the property that Level(0) ==
+// L0Sublevel(invalidSublevel).
+type Level uint32
+
+func makeLevel(level, sublevel int) Level {
+	return Level(((sublevel + 1) << levelBits) | level)
+}
+
+// LevelToInt returns the int representation of a Level
+func LevelToInt(l Level) int {
+	return int(l) & levelMask
+}
+
+// L0Sublevel returns a Level representing the specified L0 sublevel.
+func L0Sublevel(sublevel int) Level {
+	if sublevel < 0 {
+		panic(fmt.Sprintf("invalid L0 sublevel: %d", sublevel))
+	}
+	return makeLevel(0, sublevel)
+}
+
+func (l Level) String() string {
+	level := int(l) & levelMask
+	sublevel := (int(l) >> levelBits) - 1
+	if sublevel != invalidSublevel {
+		return fmt.Sprintf("L%d.%d", level, sublevel)
+	}
+	return fmt.Sprintf("L%d", level)
+}