manifest: add VersionEdit tests with virtual tables

Improve the debug parsing methods to parse virtual tables and backing
operations and add some `version_edit_apply` tests with virtual
tables.

internal/manifest/testdata/version_edit_apply

@@ -169,3 +169,49 @@ new version edit
 ----
 L2:
   000005:[s#3,SET-z#4,SET] seqnums:[0-0] points:[s#3,SET-z#4,SET]
+
+define v6
+L1:
+  000001:[a#2,SET-e#2,SET]
+L2:
+  000002:[c#1,SET-f#1,SET]
+----
+L1:
+  000001:[a#2,SET-e#2,SET] seqnums:[0-0] points:[a#2,SET-e#2,SET]
+L2:
+  000002:[c#1,SET-f#1,SET] seqnums:[0-0] points:[c#1,SET-f#1,SET]
+
+# Convert a physical table to virtual tables.
+apply v6
+  del-table: L1 000001
+  add-table: L1 000003(000009):[a#2,SET-b#2,SET]
+  add-table: L1 000004(000009):[c#2,SET-e#2,SET]
+  add-backing: 000009
+----
+L1:
+  000003(000009):[a#2,SET-b#2,SET] seqnums:[0-0] points:[a#2,SET-b#2,SET]
+  000004(000009):[c#2,SET-e#2,SET] seqnums:[0-0] points:[c#2,SET-e#2,SET]
+L2:
+  000002:[c#1,SET-f#1,SET] seqnums:[0-0] points:[c#1,SET-f#1,SET]
+
+define v7
+L1:
+  000003(000009):[a#2,SET-b#2,SET] seqnums:[0-0] points:[a#2,SET-b#2,SET]
+  000004(000009):[c#2,SET-e#2,SET] seqnums:[0-0] points:[c#2,SET-e#2,SET]
+L2:
+  000002:[c#1,SET-f#1,SET] seqnums:[0-0] points:[c#1,SET-f#1,SET]
+----
+L1:
+  000003(000009):[a#2,SET-b#2,SET] seqnums:[0-0] points:[a#2,SET-b#2,SET]
+  000004(000009):[c#2,SET-e#2,SET] seqnums:[0-0] points:[c#2,SET-e#2,SET]
+L2:
+  000002:[c#1,SET-f#1,SET] seqnums:[0-0] points:[c#1,SET-f#1,SET]
+
+# Remove virtual tables and their backing.
+apply v7
+  del-table: L1 000003
+  del-table: L1 000004
+  del-backing: 000009
+----
+L2:
+  000002:[c#1,SET-f#1,SET] seqnums:[0-0] points:[c#1,SET-f#1,SET]

internal/manifest/testutils.go

@@ -18,9 +18,9 @@ import (
 // ParseFileMetadataDebug.
 //
 // It takes a string and splits it into tokens. Tokens are separated by
-// whitespace; in addition separators ':', '[', ']', '-' are always separate
-// tokens. For example, the string `000001:[a - b]` results in tokens `000001`,
-// `:`, `[`, `a`, `-`, `b`, `]`.
+// whitespace; in addition separators "_-[]()" are always separate tokens. For
+// example, the string `000001:[a - b]` results in tokens `000001`,
+// `:`, `[`, `a`, `-`, `b`, `]`, .
 //
 // All debugParser methods throw panics instead of returning errors. The code
 // that uses a debugParser can recover them and convert them to errors.
@@ -30,7 +30,7 @@ type debugParser struct {
 	lastToken string
 }
 
-const debugParserSeparators = ":[]-"
+const debugParserSeparators = ":-[]()"
 
 func makeDebugParser(s string) debugParser {
 	p := debugParser{
@@ -138,6 +138,11 @@ func (p *debugParser) FileNum() base.FileNum {
 	return base.FileNum(p.Int())
 }
 
+// DiskFileNum parses the next token as a DiskFileNum.
+func (p *debugParser) DiskFileNum() base.DiskFileNum {
+	return base.DiskFileNum(p.Int())
+}
+
 // InternalKey parses the next token as an internal key.
 func (p *debugParser) InternalKey() base.InternalKey {
 	return base.ParsePrettyInternalKey(p.Next())

internal/manifest/version.go

@@ -822,6 +822,12 @@ func ParseFileMetadataDebug(s string) (_ *FileMetadata, err error) {
 	m := &FileMetadata{}
 	p := makeDebugParser(s)
 	m.FileNum = p.FileNum()
+	var backingNum base.DiskFileNum
+	if p.Peek() == "(" {
+		p.Expect("(")
+		backingNum = p.DiskFileNum()
+		p.Expect(")")
+	}
 	p.Expect(":", "[")
 	m.Smallest = p.InternalKey()
 	p.Expect("-")
@@ -862,7 +868,12 @@ func ParseFileMetadataDebug(s string) (_ *FileMetadata, err error) {
 		m.SmallestPointKey, m.LargestPointKey = m.Smallest, m.Largest
 		m.HasPointKeys = true
 	}
-	m.InitPhysicalBacking()
+	if backingNum == 0 {
+		m.InitPhysicalBacking()
+	} else {
+		m.Virtual = true
+		m.InitProviderBacking(backingNum, 0 /* size */)
+	}
 	return m, nil
 }
 

internal/manifest/version_edit.go

@@ -588,6 +588,17 @@ func ParseVersionEditDebug(s string) (_ *VersionEdit, err error) {
 				FileNum: num,
 			}] = nil
 
+		case "add-backing":
+			n := p.DiskFileNum()
+			ve.CreatedBackingTables = append(ve.CreatedBackingTables, &FileBacking{
+				DiskFileNum: n,
+				Size:        100,
+			})
+
+		case "del-backing":
+			n := p.DiskFileNum()
+			ve.RemovedBackingTables = append(ve.RemovedBackingTables, n)
+
 		default:
 			return nil, errors.Errorf("field %q not implemented", field)
 		}

internal/manifest/version_test.go

@@ -404,6 +404,10 @@ func TestFileMetadata_ParseRoundTrip(t *testing.T) {
 			input:  " 000001 : [ a#0,SET - z#0,DEL] points : [ a#0,SET - z#0,DEL] ",
 			output: "000001:[a#0,SET-z#0,DEL] seqnums:[0-0] points:[a#0,SET-z#0,DEL]",
 		},
+		{
+			name:  "virtual",
+			input: "000001(000008):[a#0,SET-z#0,DEL] seqnums:[0-0] points:[a#0,SET-z#0,DEL]",
+		},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {