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package ringbuf
import (
"bytes"
"io"
"testing"
)
func TestRingBufferReader(t *testing.T) {
buf := make([]byte, 2)
ring := makeRing(2, 0)
n, err := ring.Read(buf)
if err != io.EOF {
t.Error("Expected io.EOF, got", err)
}
if n != 2 {
t.Errorf("Expected to read 2 bytes, got %d", n)
}
if !bytes.Equal(buf, []byte{0, 1}) {
t.Error("Expected [0, 1], got", buf)
}
n, err = ring.Read(buf)
if err != io.EOF {
t.Error("Expected io.EOF, got", err)
}
if n != 0 {
t.Error("Expected to read 0 bytes, got", n)
}
buf = make([]byte, 4)
ring = makeRing(4, 4)
n, err = io.ReadFull(ring, buf)
if err != nil {
t.Error("Expected nil, got", err)
}
if n != 4 {
t.Errorf("Expected to read 4 bytes, got %d", n)
}
if !bytes.Equal(buf, []byte{0, 1, 2, 3}) {
t.Error("Expected [0, 1, 2, 3], got", buf)
}
n, err = ring.Read(buf)
if err != io.EOF {
t.Error("Expected io.EOF, got", err)
}
if n != 0 {
t.Error("Expected to read 0 bytes, got", n)
}
}
func makeRing(size, offset int) *ringReader {
if size != 0 && (size&(size-1)) != 0 {
panic("size must be power of two")
}
ring := make([]byte, 2*size)
for i := range ring {
ring[i] = byte(i)
}
consumer := uint64(offset)
producer := uint64(len(ring)/2 + offset)
return newRingReader(&consumer, &producer, ring)
}
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