Add BytesPipe datastructure to ioutils

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

ioutils/bytespipe_test.go

@@ -0,0 +1,81 @@
+package ioutils
+
+import "testing"
+
+func TestBytesPipeRead(t *testing.T) {
+	buf := NewBytesPipe(nil)
+	buf.Write([]byte("12"))
+	buf.Write([]byte("34"))
+	buf.Write([]byte("56"))
+	buf.Write([]byte("78"))
+	buf.Write([]byte("90"))
+	rd := make([]byte, 4)
+	n, err := buf.Read(rd)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != 4 {
+		t.Fatalf("Wrong number of bytes read: %d, should be %d", n, 4)
+	}
+	if string(rd) != "1234" {
+		t.Fatalf("Read %s, but must be %s", rd, "1234")
+	}
+	n, err = buf.Read(rd)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != 4 {
+		t.Fatalf("Wrong number of bytes read: %d, should be %d", n, 4)
+	}
+	if string(rd) != "5678" {
+		t.Fatalf("Read %s, but must be %s", rd, "5679")
+	}
+	n, err = buf.Read(rd)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != 2 {
+		t.Fatalf("Wrong number of bytes read: %d, should be %d", n, 2)
+	}
+	if string(rd[:n]) != "90" {
+		t.Fatalf("Read %s, but must be %s", rd, "90")
+	}
+}
+
+func TestBytesPipeWrite(t *testing.T) {
+	buf := NewBytesPipe(nil)
+	buf.Write([]byte("12"))
+	buf.Write([]byte("34"))
+	buf.Write([]byte("56"))
+	buf.Write([]byte("78"))
+	buf.Write([]byte("90"))
+	if string(buf.buf) != "1234567890" {
+		t.Fatalf("Buffer %s, must be %s", buf.buf, "1234567890")
+	}
+}
+
+func BenchmarkBytesPipeWrite(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		buf := NewBytesPipe(nil)
+		for j := 0; j < 1000; j++ {
+			buf.Write([]byte("pretty short line, because why not?"))
+		}
+	}
+}
+
+func BenchmarkBytesPipeRead(b *testing.B) {
+	rd := make([]byte, 1024)
+	for i := 0; i < b.N; i++ {
+		b.StopTimer()
+		buf := NewBytesPipe(nil)
+		for j := 0; j < 1000; j++ {
+			buf.Write(make([]byte, 1024))
+		}
+		b.StartTimer()
+		for j := 0; j < 1000; j++ {
+			if n, _ := buf.Read(rd); n != 1024 {
+				b.Fatalf("Wrong number of bytes: %d", n)
+			}
+		}
+	}
+}