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// Copyright 2022 CloudWeGo Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build linux
package netpoll
import (
"net"
"runtime"
"sync"
"sync/atomic"
"syscall"
"testing"
"time"
)
// TestTCPConnectionIsHealthyForReuseIdle covers the uncontended healthy fast
// path with no buffered or socket data.
func TestTCPConnectionIsHealthyForReuseIdle(t *testing.T) {
conn, _ := newReusableTCPPair(t)
if !conn.IsHealthyForReuse(time.Second) {
t.Fatal("idle connection should be reusable")
}
}
// TestTCPConnectionIsHealthyForReuseWaitsForPoller proves temporary receive
// ownership contention waits instead of immediately rejecting a healthy peer.
func TestTCPConnectionIsHealthyForReuseWaitsForPoller(t *testing.T) {
// Arrange: hold the operator to model a poller inside its receive section.
conn, _ := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
// Act: start the probe and prove it cannot bypass the current owner.
result := make(chan bool, 1)
go func() {
result <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, result)
// Assert: releasing ownership lets the healthy connection remain reusable.
releaseOperator()
if !waitReuseCheckResult(t, result) {
t.Fatal("healthy connection should remain reusable after the poller releases it")
}
}
// The poller reads from the kernel socket before it acknowledges bytes to the
// LinkBuffer. The reuse check must wait for that ownership interval, otherwise
// it can see an empty kernel socket and an empty LinkBuffer at the same time.
func TestTCPConnectionIsHealthyForReuseRejectsDataBeforeInputAck(t *testing.T) {
// Arrange: own the operator so the test controls the read/InputAck handoff.
conn, peer := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
// Move one byte out of the kernel queue without publishing it to LinkBuffer.
if _, err := peer.Write([]byte("x")); err != nil {
t.Fatalf("write peer data: %v", err)
}
buffers := conn.inputs(make([][]byte, 1))
n, err := readForReuseTest(conn.fd, buffers)
if err != nil || n != 1 {
_ = conn.inputAck(0)
t.Fatalf("drain socket before InputAck: n=%d err=%v", n, err)
}
// Act: launch the probe in that handoff gap and require it to wait.
result := make(chan bool, 1)
go func() {
result <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, result)
// Publish the byte and release ownership so the resumed probe can classify it.
if err := conn.inputAck(n); err != nil {
t.Fatalf("ack input: %v", err)
}
releaseOperator()
if waitReuseCheckResult(t, result) {
t.Fatal("connection with data drained before InputAck must not be reusable")
}
// Assert: the pending byte rejects reuse but remains intact for the reader.
data, err := conn.Peek(1)
if err != nil {
t.Fatalf("peek data after reuse check: %v", err)
}
if string(data) != "x" {
t.Fatalf("reuse check consumed or changed data: got %q", data)
}
}
// TestTCPConnectionIsHealthyForReuseRejectsUnreadDataWithoutConsuming proves
// socket data is rejected while remaining available to the application reader.
func TestTCPConnectionIsHealthyForReuseRejectsUnreadDataWithoutConsuming(t *testing.T) {
// Arrange: hold receive ownership so the peer byte stays in the socket queue.
conn, peer := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
if _, err := peer.Write([]byte("x")); err != nil {
t.Fatalf("write peer data: %v", err)
}
// Act: queue the probe behind the simulated poller, then release ownership.
result := make(chan bool, 1)
go func() {
result <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, result)
releaseOperator()
// Assert: unread data rejects reuse without being consumed by MSG_PEEK.
if waitReuseCheckResult(t, result) {
t.Fatal("connection with unread data must not be reusable")
}
data, err := conn.Peek(1)
if err != nil {
t.Fatalf("peek data after reuse check: %v", err)
}
if string(data) != "x" {
t.Fatalf("reuse check consumed or changed data: got %q", data)
}
}
// TestTCPConnectionIsHealthyForReuseRejectsPeerClose covers a FIN observed
// while the health check waits for receive ownership.
func TestTCPConnectionIsHealthyForReuseRejectsPeerClose(t *testing.T) {
// Arrange: delay the probe behind receive ownership before sending FIN.
conn, peer := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
// Act: close the peer and queue the probe before releasing the operator.
if err := peer.Close(); err != nil {
t.Fatalf("close peer: %v", err)
}
result := make(chan bool, 1)
go func() {
result <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, result)
releaseOperator()
// Assert: either the direct probe or asynchronous HUP path must reject reuse.
if waitReuseCheckResult(t, result) {
if !waitForUnhealthyForReuse(conn) {
t.Fatal("peer-closed connection must not be reusable")
}
}
}
// appendHup writes detached before it asynchronously calls OnHup. Model that
// published state directly so this contract test cannot unregister a live test
// socket from the shared poller.
func TestTCPConnectionIsHealthyForReuseRejectsDetachedOperatorBeforeOnHup(t *testing.T) {
// Arrange: publish only detached and restore it before shared-poller cleanup.
conn, _ := newReusableTCPPair(t)
atomic.StoreInt32(&conn.operator.detached, 1)
t.Cleanup(func() {
atomic.StoreInt32(&conn.operator.detached, 0)
})
// Assert the fixture isolates detach-before-OnHup, then reject reuse.
if !conn.IsActive() {
t.Fatal("probe setup unexpectedly published the closing state")
}
if conn.operator.isUnused() {
t.Fatal("probe setup unexpectedly released the operator")
}
if conn.IsHealthyForReuse(time.Second) {
t.Fatal("detached operator before OnHup must not be reusable")
}
}
// TestTCPConnectionIsHealthyForReuseRejectsClosedConnection rejects a local
// close before any receive-owner or socket work is attempted.
func TestTCPConnectionIsHealthyForReuseRejectsClosedConnection(t *testing.T) {
conn, _ := newReusableTCPPair(t)
if err := conn.Close(); err != nil {
t.Fatalf("close connection: %v", err)
}
if conn.IsHealthyForReuse(time.Second) {
t.Fatal("closed connection must not be reusable")
}
}
// TestTCPConnectionIsHealthyForReuseRejectsPeerReset covers an RST returned by
// the single nonblocking socket probe.
func TestTCPConnectionIsHealthyForReuseRejectsPeerReset(t *testing.T) {
// Arrange: configure an abortive peer close so Linux reports RST.
conn, peer := newReusableTCPPair(t)
resetPeer, ok := peer.(*net.TCPConn)
if !ok {
t.Fatalf("unexpected peer type %T", peer)
}
if err := resetPeer.SetLinger(0); err != nil {
t.Fatalf("set linger: %v", err)
}
// Act: hold receive ownership, close the peer, and queue the probe.
releaseOperator := acquireOperatorForReuseTest(t, conn)
if err := peer.Close(); err != nil {
t.Fatalf("close reset peer: %v", err)
}
result := make(chan bool, 1)
go func() {
result <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, result)
releaseOperator()
if waitReuseCheckResult(t, result) {
t.Fatal("peer-reset connection must not be reusable")
}
}
// TestTCPConnectionIsHealthyForReuseRejectsInterruptedProbe freezes the
// fail-closed EINTR classification without installing process-wide signals.
func TestTCPConnectionIsHealthyForReuseRejectsInterruptedProbe(t *testing.T) {
conn, _ := newReusableTCPPair(t)
if conn.isHealthyForReuseAfterPeek(conn.operator, syscall.EINTR) {
t.Fatal("interrupted nonblocking probe must fail closed")
}
}
// TestTCPConnectionIsHealthyForReuseRejectsNilConnection keeps the optional
// capability safe for callers holding a typed nil connection.
func TestTCPConnectionIsHealthyForReuseRejectsNilConnection(t *testing.T) {
var conn *TCPConnection
if conn.IsHealthyForReuse(time.Second) {
t.Fatal("nil connection must not be reusable")
}
}
// TestTCPConnectionIsHealthyForReuseTimesOutWaitingForPoller verifies bounded
// owner acquisition and proves a timeout does not leak operator ownership.
func TestTCPConnectionIsHealthyForReuseTimesOutWaitingForPoller(t *testing.T) {
// Arrange: retain receive ownership beyond the short probe budget.
conn, _ := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
defer releaseOperator()
// Act: measure the bounded wait while the operator remains unavailable.
timeout := 20 * time.Millisecond
started := time.Now()
if conn.IsHealthyForReuse(timeout) {
t.Fatal("connection must not be reusable when owner acquisition times out")
}
elapsed := time.Since(started)
// Assert no early return and no unbounded wait beyond test-only tolerance.
if elapsed < timeout {
t.Fatalf("reuse check returned before timeout: elapsed=%v timeout=%v", elapsed, timeout)
}
if elapsed > 10*timeout {
t.Fatalf("reuse check exceeded bounded wait: elapsed=%v timeout=%v", elapsed, timeout)
}
releaseOperator()
if !conn.IsHealthyForReuse(time.Second) {
t.Fatal("timeout must not leave operator ownership locked")
}
}
// TestTCPConnectionIsHealthyForReuseRejectsCloseWhileWaitingForPoller covers
// close serialization while the probe is queued behind the receive owner.
func TestTCPConnectionIsHealthyForReuseRejectsCloseWhileWaitingForPoller(t *testing.T) {
// Arrange: hold receive ownership and queue the probe behind it.
conn, _ := newReusableTCPPair(t)
releaseOperator := acquireOperatorForReuseTest(t, conn)
reuseResult := make(chan bool, 1)
go func() {
reuseResult <- conn.IsHealthyForReuse(time.Second)
}()
waitForReuseCheckToLockFlushing(t, conn)
assertReuseCheckBlocked(t, reuseResult)
// Act: start close only after the probe enters its flushing critical section.
closeResult := make(chan error, 1)
go func() {
closeResult <- conn.Close()
}()
assertCloseBlocked(t, closeResult)
releaseOperator()
if waitReuseCheckResult(t, reuseResult) {
t.Fatal("connection closed while waiting for the poller must not be reusable")
}
select {
case err := <-closeResult:
if err != nil {
t.Fatalf("close connection: %v", err)
}
case <-time.After(time.Second):
t.Fatal("close connection timed out")
}
}
// BenchmarkTCPConnectionIsHealthyForReuseIdle measures only the uncontended
// healthy probe after one untimed warm-up on a single loopback connection.
func BenchmarkTCPConnectionIsHealthyForReuseIdle(b *testing.B) {
conn, _ := newReusableTCPPair(b)
if !conn.IsHealthyForReuse(time.Second) {
b.Fatal("warmup rejected idle connection")
}
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
if !conn.IsHealthyForReuse(time.Second) {
b.Fatal("idle connection was rejected")
}
}
}
// newReusableTCPPair builds a real loopback connection through netpoll's
// production dialer and registers complete cleanup for both endpoints.
func newReusableTCPPair(t testing.TB) (*TCPConnection, net.Conn) {
t.Helper()
listener, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
t.Fatalf("listen: %v", err)
}
accepted := make(chan net.Conn, 1)
acceptErr := make(chan error, 1)
go func() {
peer, err := listener.Accept()
if err != nil {
acceptErr <- err
return
}
accepted <- peer
}()
rawConn, err := NewDialer().DialConnection("tcp", listener.Addr().String(), time.Second)
if err != nil {
_ = listener.Close()
t.Fatalf("dial: %v", err)
}
conn, ok := rawConn.(*TCPConnection)
if !ok {
_ = rawConn.Close()
_ = listener.Close()
t.Fatalf("unexpected connection type %T", rawConn)
}
var peer net.Conn
select {
case peer = <-accepted:
case err := <-acceptErr:
_ = conn.Close()
_ = listener.Close()
t.Fatalf("accept: %v", err)
case <-time.After(time.Second):
_ = conn.Close()
_ = listener.Close()
t.Fatal("accept timed out")
}
t.Cleanup(func() {
_ = conn.Close()
_ = peer.Close()
_ = listener.Close()
})
return conn, peer
}
// acquireOperatorForReuseTest models poller ownership and returns an idempotent
// release function so tests can safely release it explicitly and in cleanup.
func acquireOperatorForReuseTest(t *testing.T, conn *TCPConnection) func() {
t.Helper()
deadline := time.Now().Add(time.Second)
for !conn.operator.do() {
if time.Now().After(deadline) {
t.Fatal("acquire operator timed out")
}
runtime.Gosched()
}
var once sync.Once
release := func() {
once.Do(conn.operator.done)
}
t.Cleanup(release)
return release
}
// readForReuseTest drives the same ioread path as the poller until it observes
// data, an error, or the bounded test deadline.
func readForReuseTest(fd int, buffers [][]byte) (int, error) {
deadline := time.Now().Add(time.Second)
vectors := make([]syscall.Iovec, len(buffers))
for {
n, err := ioread(fd, buffers, vectors)
if n > 0 || err != nil || time.Now().After(deadline) {
return n, err
}
runtime.Gosched()
}
}
// assertReuseCheckBlocked proves the probe cannot complete while the simulated
// poller still owns the receive operator.
func assertReuseCheckBlocked(t *testing.T, result <-chan bool) {
t.Helper()
select {
case value := <-result:
t.Fatalf("reuse check returned before the poller handoff completed: %v", value)
case <-time.After(10 * time.Millisecond):
}
}
// waitForReuseCheckToLockFlushing waits until the probe has entered its close
// serialization region before the test advances a competing lifecycle event.
func waitForReuseCheckToLockFlushing(t *testing.T, conn *TCPConnection) {
t.Helper()
deadline := time.Now().Add(time.Second)
for conn.status(flushing) != 1 {
if time.Now().After(deadline) {
t.Fatal("reuse check did not acquire the flushing lock")
}
runtime.Gosched()
}
}
// assertCloseBlocked proves close remains serialized behind the in-flight
// probe and receive-owner handoff.
func assertCloseBlocked(t *testing.T, result <-chan error) {
t.Helper()
select {
case err := <-result:
t.Fatalf("close returned before the poller handoff completed: %v", err)
case <-time.After(10 * time.Millisecond):
}
}
// waitReuseCheckResult converts an asynchronous probe into a bounded test
// result and fails instead of allowing a stuck goroutine to hang the suite.
func waitReuseCheckResult(t *testing.T, result <-chan bool) bool {
t.Helper()
select {
case value := <-result:
return value
case <-time.After(time.Second):
t.Fatal("reuse check timed out")
return false
}
}
// waitForUnhealthyForReuse allows asynchronous HUP publication to converge
// when the first direct probe races the peer's FIN notification.
func waitForUnhealthyForReuse(conn *TCPConnection) bool {
deadline := time.Now().Add(time.Second)
for time.Now().Before(deadline) {
if !conn.IsHealthyForReuse(time.Second) {
return true
}
time.Sleep(time.Millisecond)
}
return false
}