leveldb, manualtest: make filterbaselg configurable

leveldb/opt/options.go

@@ -41,6 +41,7 @@ var (
 	DefaultWriteBuffer                   = 4 * MiB
 	DefaultWriteL0PauseTrigger           = 12
 	DefaultWriteL0SlowdownTrigger        = 8
+	DefaultFilterBaseLg                  = 11
 )
 
 // Cacher is a caching algorithm.
@@ -373,6 +374,11 @@ type Options struct {
 	//
 	// The default value is 8.
 	WriteL0SlowdownTrigger int
+
+	// FilterBaseLg is the log size for filter block to create a bloom filter.
+	//
+	// The default value is 11(as well as 2KB)
+	FilterBaseLg int
 }
 
 func (o *Options) GetAltFilters() []filter.Filter {
@@ -641,6 +647,13 @@ func (o *Options) GetWriteL0SlowdownTrigger() int {
 	return o.WriteL0SlowdownTrigger
 }
 
+func (o *Options) GetFilterBaseLg() int {
+	if o == nil || o.FilterBaseLg == 0 {
+		return DefaultFilterBaseLg
+	}
+	return o.FilterBaseLg
+}
+
 // ReadOptions holds the optional parameters for 'read operation'. The
 // 'read operation' includes Get, Find and NewIterator.
 type ReadOptions struct {

leveldb/table/table.go

@@ -151,10 +151,6 @@ const (
 	// These constants are part of the file format and should not be changed.
 	blockTypeNoCompression     = 0
 	blockTypeSnappyCompression = 1
-
-	// Generate new filter every 2KB of data
-	filterBaseLg = 11
-	filterBase   = 1 << filterBaseLg
 )
 
 type blockHandle struct {

leveldb/table/writer.go

@@ -89,6 +89,7 @@ type filterWriter struct {
 	buf       util.Buffer
 	nKeys     int
 	offsets   []uint32
+	baseLg    int
 }
 
 func (w *filterWriter) add(key []byte) {
@@ -103,7 +104,7 @@ func (w *filterWriter) flush(offset uint64) {
 	if w.generator == nil {
 		return
 	}
-	for x := int(offset / filterBase); x > len(w.offsets); {
+	for x := int(offset / uint64(1<<w.baseLg)); x > len(w.offsets); {
 		w.generate()
 	}
 }
@@ -122,7 +123,7 @@ func (w *filterWriter) finish() {
 		buf4 := w.buf.Alloc(4)
 		binary.LittleEndian.PutUint32(buf4, x)
 	}
-	w.buf.WriteByte(filterBaseLg)
+	w.buf.WriteByte(byte(w.baseLg))
 }
 
 func (w *filterWriter) generate() {
@@ -369,6 +370,7 @@ func NewWriter(f io.Writer, o *opt.Options) *Writer {
 	// filter block
 	if w.filter != nil {
 		w.filterBlock.generator = w.filter.NewGenerator()
+		w.filterBlock.baseLg = o.GetFilterBaseLg()
 		w.filterBlock.flush(0)
 	}
 	return w

manualtest/dbstress/main.go

@@ -21,6 +21,7 @@ import (
 
 	"github.com/syndtr/goleveldb/leveldb"
 	"github.com/syndtr/goleveldb/leveldb/errors"
+	"github.com/syndtr/goleveldb/leveldb/filter"
 	"github.com/syndtr/goleveldb/leveldb/opt"
 	"github.com/syndtr/goleveldb/leveldb/storage"
 	"github.com/syndtr/goleveldb/leveldb/table"
@@ -350,6 +351,7 @@ func main() {
 		DisableBlockCache:      !enableBlockCache,
 		ErrorIfExist:           true,
 		Compression:            opt.NoCompression,
+		Filter:                 filter.NewBloomFilter(10),
 	}
 	if enableCompression {
 		o.Compression = opt.DefaultCompression