func TestLimitedConnListenerAccept(t *testing.T) {
if _, err := runtime.FDUsage(); err != nil {
t.Skip("skip test due to unsupported runtime.FDUsage")
}
ln, err := net.Listen("tcp", ":0")
if err != nil {
t.Fatal(err)
}
fdNum, err := runtime.FDUsage()
if err != nil {
t.Fatal(err)
}
srv := &httptest.Server{
Listener: &LimitedConnListener{
Listener: ln,
RuntimeFDLimit: fdNum + 100,
},
Config: &http.Server{},
}
srv.Start()
defer srv.Close()
resp, err := http.Get(srv.URL)
defer resp.Body.Close()
if err != nil {
t.Fatalf("Get error = %v, want nil", err)
}
}
func monitorFileDescriptor(done <-chan struct{}) {
ticker := time.NewTicker(5 * time.Second)
defer ticker.Stop()
for {
used, err := runtime.FDUsage()
if err != nil {
plog.Errorf("cannot monitor file descriptor usage (%v)", err)
return
}
fileDescriptorUsed.Set(float64(used))
limit, err := runtime.FDLimit()
if err != nil {
plog.Errorf("cannot monitor file descriptor usage (%v)", err)
return
}
if used >= limit/5*4 {
plog.Warningf("80%% of the file descriptor limit is used [used = %d, limit = %d]", used, limit)
}
select {
case <-ticker.C:
case <-done:
return
}
}
}
func (l *LimitedConnListener) Accept() (net.Conn, error) {
conn, err := l.Listener.Accept()
if err != nil {
return nil, err
}
n, err := runtime.FDUsage()
// Check whether fd number in use exceeds the set limit.
if err == nil && n >= l.RuntimeFDLimit {
conn.Close()
plog.Errorf("accept error: closing connection, exceed file descriptor usage limitation (fd limit=%d)", l.RuntimeFDLimit)
return nil, &acceptError{error: errors.New("exceed file descriptor usage limitation"), temporary: true}
}
return conn, nil
}
func TestLimitedConnListenerLimit(t *testing.T) {
if _, err := runtime.FDUsage(); err != nil {
t.Skip("skip test due to unsupported runtime.FDUsage")
}
ln, err := net.Listen("tcp", ":0")
if err != nil {
t.Fatal(err)
}
srv := &httptest.Server{
Listener: &LimitedConnListener{
Listener: ln,
RuntimeFDLimit: 0,
},
Config: &http.Server{},
}
srv.Start()
defer srv.Close()
_, err = http.Get(srv.URL)
if err == nil {
t.Fatalf("unexpected nil Get error")
}
}