.

t/neo/storage/fs1/cmd/fstail/fstail_test.go

@@ -45,6 +45,7 @@ func TestFsTail(t *testing.T) {
 }
 
 func BenchmarkFsTail(b *testing.B) {
+	// FIXME small testdata/1.fs is not representative for benchmarking
 	for i := 0; i < b.N; i++ {
 		err := fsTail(ioutil.Discard, "../../testdata/1.fs", 1000000)
 		if err != nil {

t/neo/storage/fs1/filestorage.go

@@ -19,11 +19,11 @@ package fs1
 import (
 	"encoding/binary"
 	"fmt"
-	"math/bits"
 	"io"
 	"os"
 
 	"../../zodb"
+	"../../xcommon/xmath"
 )
 
 // FileStorage is a ZODB storage which stores data in simple append-only file
@@ -315,7 +315,7 @@ func (txnh *TxnHeader) Load(r io.ReaderAt /* *os.File */, pos int64, flags TxnLo
 
 	// NOTE we encode whole strings length into len(.workMem)
 	if cap(txnh.workMem) < lstr {
-		txnh.workMem = make([]byte, lstr, ceilPow2(uint64(lstr)))
+		txnh.workMem = make([]byte, lstr, xmath.CeilPow2(uint64(lstr)))
 	} else {
 		txnh.workMem = txnh.workMem[:lstr]
 	}
@@ -635,12 +635,6 @@ func (dh *DataHeader) loadNext(r io.ReaderAt /* *os.File */, txnh *TxnHeader) er
 	return nil
 }
 
-// XXX move me out of here
-// ceilPow2 returns minimal y >= x, such as y = 2^i
-func ceilPow2(x uint64) uint64 {
-	return 1 << uint(bits.Len64(x))
-}
-
 // LoadData loads data for the data record taking backpointers into account
 // Data is loaded into *buf, which, if needed, is reallocated to hold all loading data size	XXX
 // NOTE on success dh state is changed to data header of original data transaction
@@ -660,9 +654,7 @@ func (dh *DataHeader) LoadData(r io.ReaderAt /* *os.File */, buf *[]byte)  error
 
 	// now read actual data
 	if int64(cap(*buf)) < dh.DataLen {
-		// ceilPow2 reduces much allocations but is still not enogh to
-		// remove them all from BenchmarkIterate
-		*buf = make([]byte, dh.DataLen, ceilPow2(uint64(dh.DataLen)))
+		*buf = make([]byte, dh.DataLen, xmath.CeilPow2(uint64(dh.DataLen)))
 	} else {
 		*buf = (*buf)[:dh.DataLen]
 	}

t/neo/xcommon/xcommon.go

+// Package xcommon is a staging place for common utilities not yet sorted out
+// to their proper homes
+package xcommon

t/neo/xcommon/xfmt/fmt.go

+package xfmt
+
+import (
+	"encoding/hex"
+
+	"../xslice"
+)
+
+// appendHex appends hex representation of x to b
+func AppendHex(b []byte, x []byte) []byte {
+	lx := hex.EncodedLen(len(x))
+	lb := len(b)
+	b = xslice.Grow(b, lx)
+	hex.Encode(b[lb:], x)
+	return b
+}

t/neo/xcommon/xmath/math.go

+// Package xmath provides addons over std math package	XXX text
+package xmath
+
+import (
+	"math/bits"
+)
+
+// CeilPow2 returns minimal y >= x, such that y = 2^i
+// XXX naming to reflect it works on uint64 ? CeilPow264 looks ambigous
+func CeilPow2(x uint64) uint64 {
+	switch bits.OnesCount64(x) {
+	case 0, 1:
+		return x // either 0 or 2^i already
+	default:
+		return 1 << uint(bits.Len64(x))
+	}
+}
+
+// XXX if needed: NextPow2 (y > x, such that y = 2^i) is
+//	1 << bits.Len64(x)

t/neo/xcommon/xmath/math_test.go

+package xmath
+
+import (
+	"testing"
+)
+
+func TestCeilPow2(t *testing.T) {
+	testv := []struct {in, out uint64} {
+		{0, 0},
+		{1, 1},
+		{2, 2},
+		{3, 4},
+		{4, 4},
+		{5, 8},
+		{5, 8},
+		{6, 8},
+		{7, 8},
+		{8, 8},
+		{9, 16},
+		{10, 16},
+		{11, 16},
+		{12, 16},
+		{13, 16},
+		{14, 16},
+		{15, 16},
+		{16, 16},
+		{1<<62 - 1, 1<<62},
+		{1<<62, 1<<62},
+		{1<<62+1, 1<<63},
+		{1<<63 - 1, 1<<63},
+		{1<<63, 1<<63},
+	}
+
+	for _, tt := range testv {
+		out := CeilPow2(tt.in)
+		if out != tt.out {
+			t.Errorf("CeilPow(%v) -> %v  ; want %v", tt.in, out, tt.out)
+		}
+	}
+
+}

t/neo/xcommon/xslice/slice.go

+// Package xslice provides utilities for working with slices
+package xslice
+
+import (
+	"../xmath"
+)
+
+// Grow increase length of slice by n elements.
+// If there is not enough capacity the slice is reallocated.
+// The memory for grown elements are not initialized.
+func Grow(b []byte, n int) []byte {
+	ln := len(b) + n
+	if ln <= cap(b) {
+		return b[:ln]
+	}
+
+	bb := make([]byte, ln, xmath.CeilPow2(uint64(ln)))
+	copy(bb, b)
+	return bb
+}
+
+// Resize resized the slice to be of length n.
+// If slice length is increased and there is not enough capacity the slice is reallocated.
+// The memory for grown elements, if any, is not initialized.
+func Resize(b []byte, n int) []byte {
+	if cap(b) >= n {
+		return b[:n]
+	}
+
+	bb := make([]byte, n, xmath.CeilPow2(uint64(n)))
+	copy(bb, b)
+	return bb
+}
+
+
+// TODO Resize without copy ?
+
+// // GrowSlice makes sure cap(b) >= n.
+// // If not it reallocates/copies the slice appropriately.
+// // len of returned slice remains original len(b).
+// func GrowSlice(b []byte, n int) []byte {
+// 	if cap(b) >= n {
+// 		return b
+// 	}
+// 
+// 	bb := make([]byte, len(b), CeilPow2(uint64(n)))
+// 	copy(bb, b)
+// 	return bb
+// }
+// 
+// // makeRoom makes sure len([len(b):cap(b)]) >= n.
+// // If it is not it reallocates the slice appropriately.
+// // len of returned slice remains original len(b).
+// func MakeRoom(b []byte, n int) []byte {
+// 	return GrowSlice(b, len(b) + n)
+// }

t/neo/xcommon/xslice/slice_test.go

+package xslice
+
+//import (
+//	"testing"
+//)
+
+// TODO
+
+// func TestGrowSlice(t *testing) {
+// 	testv := []struct {in []byte, n int, Cap int} {
+// 		{nil, 0, 0},
+// 	}
+// 
+// }

t/neo/zodb/cmd/zodbdump/zodbdump_test.go

@@ -55,9 +55,7 @@ func loadZdumpPy(t *testing.T, path string) string {
 	return string(dump)
 }
 
-
-func TestZodbDump(t *testing.T) {
-	buf := bytes.Buffer{}
+func withTestdata1Fs(t testing.TB, f func(fs *fs1.FileStorage)) {
 	fs, err := fs1.Open("../../../storage/fs1/testdata/1.fs")	// XXX read-only, path?
 	if err != nil {
 		t.Fatal(err)
@@ -65,7 +63,14 @@ func TestZodbDump(t *testing.T) {
 
 	defer exc.XRun(fs.Close)
 
-	err = zodbDump(&buf, fs, 0, zodb.TidMax, false)
+	f(fs)
+}
+
+func TestZodbDump(t *testing.T) {
+	withTestdata1Fs(t, func(fs *fs1.FileStorage) {
+		buf := bytes.Buffer{}
+
+		err := zodbDump(&buf, fs, 0, zodb.TidMax, false)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -75,4 +80,22 @@ func TestZodbDump(t *testing.T) {
 		if dumpOk != buf.String() {
 			t.Errorf("dump different:\n%v", diff(dumpOk, buf.String()))
 		}
+	})
+}
+
+
+func BenchmarkZodbDump(b *testing.B) {
+	// FIXME small testdata/1.fs is not representative for benchmarking
+	withTestdata1Fs(b, func(fs *fs1.FileStorage) {
+		b.ResetTimer()
+
+		for i := 0; i < b.N; i++ {
+			err := zodbDump(ioutil.Discard, fs, 0, zodb.TidMax, false)
+			if err != nil {
+				b.Fatal(err)
+			}
+		}
+
+		b.StopTimer()
+	})
 }