sstable: support columnar blocks in Layout.Describe

Adapt Layout.Describe to support describing sstables containing columnar
blocks.

internal/binfmt/binfmt.go

@@ -36,9 +36,15 @@ type Formatter struct {
 
 	// config
 	lineWidth       int
+	linePrefix      string
 	offsetFormatStr string
 }
 
+// SetLinePrefix sets a prefix for each line of formatted output.
+func (f *Formatter) SetLinePrefix(prefix string) {
+	f.linePrefix = prefix
+}
+
 // SetAnchorOffset sets the reference point for relative offset calculations to
 // the current offset. Future calls to RelativeOffset() will return an offset
 // relative to the current offset.
@@ -183,6 +189,7 @@ func (f *Formatter) String() string {
 		binaryLineWidth = max(binaryLineWidth, len(lineData[0]))
 	}
 	for _, lineData := range f.lines {
+		fmt.Fprint(&f.buf, f.linePrefix)
 		fmt.Fprint(&f.buf, lineData[0])
 		if len(lineData[1]) > 0 {
 			if len(lineData[0]) == 0 {

sstable/colblk/data_block.go

@@ -759,8 +759,9 @@ func (i *DataBlockIter) Init(
 		keyIter:       PrefixBytesIter{},
 	}
 	// Allocate a keyIter buffer that's large enough to hold the largest user
-	// key in the block.
-	n := int(r.maximumKeyLength)
+	// key in the block with 1 byte to spare (so that pointer arithmetic is
+	// never pointing beyond the allocation, which would violate Go rules).
+	n := int(r.maximumKeyLength) + 1
 	if cap(i.keyIter.buf) < n {
 		ptr := mallocgc(uintptr(n), nil, false)
 		i.keyIter.buf = unsafe.Slice((*byte)(ptr), n)[:0]

sstable/colblk_writer.go

@@ -662,7 +662,6 @@ func (w *RawColumnWriter) flushBufferedIndexBlocks() (rootIndex block.Handle, er
 	// writing a large file or the index separators happen to be excessively
 	// long, we may have several index blocks and need to construct a
 	// "two-level" index structure.
-	w.props.IndexPartitions = uint64(len(w.indexBuffering.partitions))
 	switch len(w.indexBuffering.partitions) {
 	case 0:
 		// This is impossible because we'll flush the index block immediately
@@ -696,6 +695,7 @@ func (w *RawColumnWriter) flushBufferedIndexBlocks() (rootIndex block.Handle, er
 		}
 		w.props.IndexSize += rootIndex.Length + block.TrailerLen
 		w.props.IndexType = twoLevelIndex
+		w.props.IndexPartitions = uint64(len(w.indexBuffering.partitions))
 	}
 	return rootIndex, nil
 }

sstable/colblk_writer_test.go

@@ -5,6 +5,7 @@
 package sstable
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"testing"
@@ -30,8 +31,10 @@ func TestColumnarWriter(t *testing.T) {
 		}
 	}()
 	keySchema := colblk.DefaultKeySchema(testkeys.Comparer, 16)
+	var buf bytes.Buffer
 	datadriven.Walk(t, "testdata/columnar_writer", func(t *testing.T, path string) {
 		datadriven.RunTest(t, path, func(t *testing.T, td *datadriven.TestData) string {
+			buf.Reset()
 			switch td.Cmd {
 			case "build":
 				var writerOpts WriterOptions
@@ -60,6 +63,13 @@ func TestColumnarWriter(t *testing.T) {
 				})
 				require.NoError(t, err)
 				return "ok"
+			case "layout":
+				l, err := r.Layout()
+				if err != nil {
+					return err.Error()
+				}
+				l.Describe(&buf, true /* verbose */, r, nil)
+				return buf.String()
 			case "props":
 				return r.Properties.String()
 			case "describe-binary":

sstable/format.go

@@ -7,6 +7,9 @@ package sstable
 import (
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/pebble/internal/base"
+	"github.com/cockroachdb/pebble/sstable/block"
+	"github.com/cockroachdb/pebble/sstable/colblk"
+	"github.com/cockroachdb/pebble/sstable/rowblk"
 )
 
 // TableFormat specifies the format version for sstables. The legacy LevelDB
@@ -251,6 +254,13 @@ func (f TableFormat) BlockColumnar() bool {
 	return f >= TableFormatPebblev5
 }
 
+func (f TableFormat) newIndexIter() block.IndexBlockIterator {
+	if !f.BlockColumnar() {
+		return new(rowblk.IndexIter)
+	}
+	return new(colblk.IndexIter)
+}
+
 // AsTuple returns the TableFormat's (Magic String, Version) tuple.
 func (f TableFormat) AsTuple() (string, uint32) {
 	switch f {