[WIP] lint a bit, update deps

vendor/github.com/cockroachdb/pebble/sstable/table.go

@@ -68,8 +68,8 @@
 package sstable // import "github.com/cockroachdb/pebble/sstable"
 
 import (
+	"context"
 	"encoding/binary"
-	"io"
 
 	"github.com/cockroachdb/errors"
 	"github.com/cockroachdb/pebble/internal/base"
@@ -160,8 +160,27 @@ The metaindex block also contains block handles as values, with keys being
 the names of the meta blocks.
 
 For a description of value blocks and the meta value index block, see
-value_block.go
+value_block.go.
 
+Data blocks have some additional features:
+- For TableFormatPebblev3 onwards:
+  - For SETs, the value has a 1 byte value prefix, which indicates whether the
+    value is inline, or in a separate value block, and indicates whether the
+    prefix of the userkey (as defined by split) has changed or not. See
+    value_block.go for details.
+  - The most significant bit of the restart points is used to indicate whether
+    userkey prefix has changed since the last restart point. See the detailed
+    comment in blockWriter.
+  - The maximum length of the "shared prefix" when encoding the key, is the
+    length of the prefix of the userkey (as defined by split) of the previous
+    key.
+
+- For TableFormatPebblev4 onwards:
+  - The key kinds may be altered to set the
+    InternalKeyKindSSTableInternalObsoleteBit if the key-value pair is obsolete
+    in the context of that sstable (for a reader that reads at a higher seqnum
+    than the highest seqnum in the sstable). For details, see the comment in
+    format.go.
 */
 
 const (
@@ -316,12 +335,11 @@ func readFooter(f objstorage.Readable) (footer, error) {
 	off := size - maxFooterLen
 	if off < 0 {
 		off = 0
+		buf = buf[:size]
 	}
-	n, err := f.ReadAt(buf, off)
-	if err != nil && err != io.EOF {
+	if err := f.ReadAt(context.TODO(), buf, off); err != nil {
 		return footer, errors.Wrap(err, "pebble/table: invalid table (could not read footer)")
 	}
-	buf = buf[:n]
 
 	switch magic := buf[len(buf)-len(rocksDBMagic):]; string(magic) {
 	case levelDBMagic:
@@ -429,7 +447,7 @@ func supportsTwoLevelIndex(format TableFormat) bool {
 	switch format {
 	case TableFormatLevelDB:
 		return false
-	case TableFormatRocksDBv2, TableFormatPebblev1, TableFormatPebblev2, TableFormatPebblev3:
+	case TableFormatRocksDBv2, TableFormatPebblev1, TableFormatPebblev2, TableFormatPebblev3, TableFormatPebblev4:
 		return true
 	default:
 		panic("sstable: unspecified table format version")