NsdManager.discoverServicesの二重起動を行わないようにしたい

表題の件のついて質問があります。
NsdManagerを使用してDNS検索を5秒間行う機能を実装しました。
discoverServicesを実行中に再度discoverServicesを行うと

java.lang.IllegalArgumentException: listener already in use at android.net.nsd.NsdManager.resolveServiceが発生します。
discoverServicesが起動中かどうかを調べる方法を教えてください。

java
1public class DiscActivity extends Activity
2{
3    private static final String TAG = "DiscActivity";
4    private static final long DEFAULT_TIMEOUT = 5000;
5
6    private NsdManager mManager;
7    private NsdManager.DiscoveryListener mDiscListener = null;
8    private NsdManager.ResolveListener mFoundResListener = null;
9    private NsdManager.ResolveListener mLostResListener = null;
10
11    @Override
12    protected void onCreate(Bundle savedInstanceState)
13    {
14        super.onCreate(savedInstanceState);
15        setContentView(R.layout.activity_disc);
16
17        mContext = this;
18        mAdapter = new ServiceAdapter();
19
20        mManager = (NsdManager) mContext.getSystemService(Context.NSD_SERVICE);
21
22        mDiscListener = new NsdManager.DiscoveryListener()
23        {
24            String mService;
25
26            @Override
27            public void onDiscoveryStarted(String serviceType)
28            {
29                Log.v(TAG, "Service started for protocol: " + serviceType);
30            }
31
32            @Override
33            public void onDiscoveryStopped(String serviceType)
34            {
35                Log.v(TAG, "Service stopped for protocol: " + serviceType);
36            }
37
38            @Override
39            public void onServiceFound(NsdServiceInfo info)
40            {
41                Log.v(TAG, "Found service: " + info.getServiceName());
42                mManager.resolveService(info, mFoundResListener);
43            }
44
45            @Override
46            public void onServiceLost(NsdServiceInfo info)
47            {
48                Log.v(TAG, "Lost service: " + info.getServiceName());
49                mManager.resolveService(info, mLostResListener);
50            }
51
52            @Override
53            public void onStartDiscoveryFailed(String serviceType, int err)
54            {
55                mService = serviceType;
56                Log.v(TAG, "Service failed to start for protocol: " + serviceType + ", Err: " + err);
57            }
58
59            @Override
60            public void onStopDiscoveryFailed(String serviceType, int err)
61            {
62                mService = serviceType;
63
64                Log.v(TAG, "Service failed to stop for protocol: " + serviceType + ", Err: " + err);
65            }
66
67        };
68
69        mFoundResListener = new NsdManager.ResolveListener()
70        {
71            @Override
72            public void onServiceResolved(NsdServiceInfo info)
73            {
74                Log.v(TAG, "Resolve service complete");
75            }
76
77            @Override
78            public void onResolveFailed(NsdServiceInfo info, int err)
79            {
80                Log.e(TAG, "Cannot resolve service " + info.getServiceName() +
81                    ", Err: " + err);
82            }
83        };
84
85        mLostResListener = new NsdManager.ResolveListener()
86        {
87            @Override
88            public void onServiceResolved(NsdServiceInfo info)
89            {
90                Log.v(TAG, "Resolve service complete");
91            }
92
93            @Override
94            public void onResolveFailed(NsdServiceInfo info, int err)
95            {
96                Log.e(TAG, "Cannot resolve service " + info.getServiceName() +
97                    ", Err: " + err);
98            }
99        };
100
101        searchButton.setOnClickListener(new OnClickListener()
102        {
103            @Override
104            public void onClick(View v)
105            {
106                startDiscovery();
107            }
108        });
109
110    }
111
112    private void startDiscovery()
113    {
114        String service;
115
116        service = serviceNameEdit.getText().toString();
117
118        mManager.discoverServices(service, NsdManager.PROTOCOL_DNS_SD, mDiscListener);
119
120    }
121
122}