Make bytesPipe use linear allocations

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

ioutils/bytespipe_test.go

@@ -1,6 +1,10 @@
 package ioutils
 
-import "testing"
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"testing"
+)
 
 func TestBytesPipeRead(t *testing.T) {
 	buf := NewBytesPipe(nil)
@@ -49,11 +53,67 @@ func TestBytesPipeWrite(t *testing.T) {
 	buf.Write([]byte("56"))
 	buf.Write([]byte("78"))
 	buf.Write([]byte("90"))
-	if string(buf.buf) != "1234567890" {
+	if string(buf.buf[0]) != "1234567890" {
 		t.Fatalf("Buffer %s, must be %s", buf.buf, "1234567890")
 	}
 }
 
+// Write and read in different speeds/chunk sizes and check valid data is read.
+func TestBytesPipeWriteRandomChunks(t *testing.T) {
+	cases := []struct{ iterations, writesPerLoop, readsPerLoop int }{
+		{100, 10, 1},
+		{1000, 10, 5},
+		{1000, 100, 0},
+		{1000, 5, 6},
+		{10000, 50, 25},
+	}
+
+	testMessage := []byte("this is a random string for testing")
+	// random slice sizes to read and write
+	writeChunks := []int{25, 35, 15, 20}
+	readChunks := []int{5, 45, 20, 25}
+
+	for _, c := range cases {
+		// first pass: write directly to hash
+		hash := sha1.New()
+		for i := 0; i < c.iterations*c.writesPerLoop; i++ {
+			if _, err := hash.Write(testMessage[:writeChunks[i%len(writeChunks)]]); err != nil {
+				t.Fatal(err)
+			}
+		}
+		expected := hex.EncodeToString(hash.Sum(nil))
+
+		// write/read through buffer
+		buf := NewBytesPipe(nil)
+		hash.Reset()
+		for i := 0; i < c.iterations; i++ {
+			for w := 0; w < c.writesPerLoop; w++ {
+				buf.Write(testMessage[:writeChunks[(i*c.writesPerLoop+w)%len(writeChunks)]])
+			}
+			for r := 0; r < c.readsPerLoop; r++ {
+				p := make([]byte, readChunks[(i*c.readsPerLoop+r)%len(readChunks)])
+				n, _ := buf.Read(p)
+				hash.Write(p[:n])
+			}
+		}
+		// read rest of the data from buffer
+		for i := 0; ; i++ {
+			p := make([]byte, readChunks[(c.iterations*c.readsPerLoop+i)%len(readChunks)])
+			n, _ := buf.Read(p)
+			if n == 0 {
+				break
+			}
+			hash.Write(p[:n])
+		}
+		actual := hex.EncodeToString(hash.Sum(nil))
+
+		if expected != actual {
+			t.Fatalf("BytesPipe returned invalid data. Expected checksum %v, got %v", expected, actual)
+		}
+
+	}
+}
+
 func BenchmarkBytesPipeWrite(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		buf := NewBytesPipe(nil)