/
reader_test.go
260 lines (219 loc) · 5.35 KB
/
reader_test.go
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package ringbuf
import (
"errors"
"syscall"
"testing"
"time"
"github.com/cilium/ebpf"
"github.com/cilium/ebpf/asm"
"github.com/cilium/ebpf/internal/testutils"
"github.com/google/go-cmp/cmp"
)
func TestRingbufReader(t *testing.T) {
testutils.SkipOnOldKernel(t, "5.8", "BPF ring buffer")
readerTests := []struct {
name string
messages []int
want map[int][]byte
}{
{
name: "send one short sample",
messages: []int{5},
want: map[int][]byte{
5: {1, 2, 3, 4, 4},
},
},
{
name: "send three short samples, the second is discarded",
messages: []int{5, 10, 15},
want: map[int][]byte{
5: {1, 2, 3, 4, 4},
15: {1, 2, 3, 4, 4, 3, 2, 1, 1, 2, 3, 4, 4, 3, 2},
},
},
}
for _, tt := range readerTests {
t.Run(tt.name, func(t *testing.T) {
prog, events := mustOutputSamplesProg(t, 0, tt.messages...)
rd, err := NewReader(events)
if err != nil {
t.Fatal(err)
}
defer rd.Close()
ret, _, err := prog.Test(make([]byte, 14))
testutils.SkipIfNotSupported(t, err)
if err != nil {
t.Fatal(err)
}
if errno := syscall.Errno(-int32(ret)); errno != 0 {
t.Fatal("Expected 0 as return value, got", errno)
}
raw := make(map[int][]byte)
for len(raw) < len(tt.want) {
record, err := rd.Read()
if err != nil {
t.Fatal("Can't read samples:", err)
}
raw[len(record.RawSample)] = record.RawSample
}
if diff := cmp.Diff(tt.want, raw); diff != "" {
t.Errorf("Read samples mismatch (-want +got):\n%s", diff)
}
})
}
}
func outputSamplesProg(flags int32, sampleSizes ...int) (*ebpf.Program, *ebpf.Map, error) {
events, err := ebpf.NewMap(&ebpf.MapSpec{
Type: ebpf.RingBuf,
MaxEntries: 4096,
})
if err != nil {
return nil, nil, err
}
var maxSampleSize int
for _, sampleSize := range sampleSizes {
if sampleSize > maxSampleSize {
maxSampleSize = sampleSize
}
}
insns := asm.Instructions{
asm.LoadImm(asm.R0, 0x0102030404030201, asm.DWord),
asm.Mov.Reg(asm.R9, asm.R1),
}
bufDwords := (maxSampleSize / 8) + 1
for i := 0; i < bufDwords; i++ {
insns = append(insns,
asm.StoreMem(asm.RFP, int16(i+1)*-8, asm.R0, asm.DWord),
)
}
for sampleIdx, sampleSize := range sampleSizes {
insns = append(insns,
asm.LoadMapPtr(asm.R1, events.FD()),
asm.Mov.Imm(asm.R2, int32(sampleSize)),
asm.Mov.Imm(asm.R3, int32(0)),
asm.FnRingbufReserve.Call(),
asm.JEq.Imm(asm.R0, 0, "exit"),
asm.Mov.Reg(asm.R5, asm.R0),
)
for i := 0; i < sampleSize; i++ {
insns = append(insns,
asm.LoadMem(asm.R4, asm.RFP, int16(i+1)*-1, asm.Byte),
asm.StoreMem(asm.R5, int16(i), asm.R4, asm.Byte),
)
}
// discard every even sample
if sampleIdx&1 != 0 {
insns = append(insns,
asm.Mov.Reg(asm.R1, asm.R5),
asm.Mov.Imm(asm.R2, flags),
asm.FnRingbufDiscard.Call(),
)
} else {
insns = append(insns,
asm.Mov.Reg(asm.R1, asm.R5),
asm.Mov.Imm(asm.R2, flags),
asm.FnRingbufSubmit.Call(),
)
}
}
insns = append(insns,
asm.Mov.Imm(asm.R0, int32(0)).WithSymbol("exit"),
asm.Return(),
)
prog, err := ebpf.NewProgram(&ebpf.ProgramSpec{
License: "MIT",
Type: ebpf.XDP,
Instructions: insns,
})
if err != nil {
events.Close()
return nil, nil, err
}
return prog, events, nil
}
func mustOutputSamplesProg(tb testing.TB, flags int32, sampleSizes ...int) (*ebpf.Program, *ebpf.Map) {
tb.Helper()
prog, events, err := outputSamplesProg(flags, sampleSizes...)
if err != nil {
tb.Fatal(err)
}
tb.Cleanup(func() {
prog.Close()
events.Close()
})
return prog, events
}
func TestRingbufReaderClose(t *testing.T) {
testutils.SkipOnOldKernel(t, "5.8", "BPF ring buffer")
_, events := mustOutputSamplesProg(t, 0, 5)
rd, err := NewReader(events)
if err != nil {
t.Fatal(err)
}
defer rd.Close()
errs := make(chan error, 1)
waiting := make(chan struct{})
go func() {
close(waiting)
_, err := rd.Read()
errs <- err
}()
<-waiting
// Close should interrupt blocking Read
if err := rd.Close(); err != nil {
t.Fatal(err)
}
select {
case err := <-errs:
if !errors.Is(err, ErrClosed) {
t.Fatal("Read from RingbufReader that got closed does return ErrClosed")
}
case <-time.After(time.Second):
t.Fatal("Close doesn't interrupt Read")
}
// And we should be able to call it multiple times
if err := rd.Close(); err != nil {
t.Fatal(err)
}
if _, err := rd.Read(); !errors.Is(err, ErrClosed) {
t.Fatal("Second Read on a closed RingbufReader doesn't return ErrClosed")
}
}
func BenchmarkReader(b *testing.B) {
testutils.SkipOnOldKernel(b, "5.8", "BPF ring buffer")
readerBenchmarks := []struct {
name string
flags int32
}{
{
name: "normal epoll with timeout -1",
},
}
for _, bm := range readerBenchmarks {
b.Run(bm.name, func(b *testing.B) {
prog, events := mustOutputSamplesProg(b, bm.flags, 80)
rd, err := NewReader(events)
if err != nil {
b.Fatal(err)
}
defer rd.Close()
buf := make([]byte, 14)
b.ResetTimer()
b.ReportAllocs()
var sampleBuf []byte
for i := 0; i < b.N; i++ {
ret, _, err := prog.Test(buf)
if err != nil {
b.Fatal(err)
} else if errno := syscall.Errno(-int32(ret)); errno != 0 {
b.Fatal("Expected 0 as return value, got", errno)
}
record, err := rd.ReadBuffer(sampleBuf)
if err != nil {
b.Fatal("Can't read samples:", err)
}
sampleBuf = record.RawSample
}
})
}
}