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      1 /*
      2  * Copyright (C) 2016 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.printservice.recommendation.plugin.hp;
     18 
     19 import android.net.nsd.NsdManager;
     20 import android.net.nsd.NsdServiceInfo;
     21 import android.util.Pair;
     22 import com.android.printservice.recommendation.util.NsdResolveQueue;
     23 
     24 import java.util.LinkedList;
     25 
     26 final class ServiceResolveQueue {
     27 
     28     private final NsdManager mNsdManager;
     29     private final LinkedList<Pair<NsdServiceInfo, ResolveCallback>> mQueue = new LinkedList<>();
     30     private final Object mLock = new Object();
     31 
     32     private static Object sLock = new Object();
     33     private static ServiceResolveQueue sInstance = null;
     34     private final NsdResolveQueue mNsdResolveQueue;
     35     private Pair<NsdServiceInfo, ResolveCallback> mCurrentRequest = null;
     36 
     37     public static void createInstance(NsdManager nsdManager) {
     38         if (sInstance == null) sInstance = new ServiceResolveQueue(nsdManager);
     39     }
     40 
     41     public static ServiceResolveQueue getInstance(NsdManager nsdManager) {
     42         synchronized (sLock) {
     43             createInstance(nsdManager);
     44             return sInstance;
     45         }
     46     }
     47 
     48     public static void destroyInstance() {
     49         sInstance = null;
     50     }
     51 
     52     public interface ResolveCallback {
     53         void serviceResolved(NsdServiceInfo nsdServiceInfo);
     54     }
     55 
     56     public ServiceResolveQueue(NsdManager nsdManager) {
     57         mNsdManager = nsdManager;
     58         mNsdResolveQueue = NsdResolveQueue.getInstance();
     59     }
     60 
     61     public void queueRequest(NsdServiceInfo serviceInfo, ResolveCallback callback) {
     62         synchronized (mLock) {
     63             Pair<NsdServiceInfo, ResolveCallback> newRequest = Pair.create(serviceInfo, callback);
     64             if (mQueue.contains(newRequest)) return;
     65             mQueue.add(newRequest);
     66             makeNextRequest();
     67         }
     68     }
     69 
     70     public void removeRequest(NsdServiceInfo serviceInfo, ResolveCallback callback) {
     71         synchronized (mLock) {
     72             Pair<NsdServiceInfo, ResolveCallback> newRequest = Pair.create(serviceInfo, callback);
     73             mQueue.remove(newRequest);
     74             if ((mCurrentRequest != null) && newRequest.equals(mCurrentRequest)) mCurrentRequest = null;
     75         }
     76     }
     77 
     78     private void makeNextRequest() {
     79         synchronized (mLock) {
     80             if (mCurrentRequest != null) return;
     81             if (mQueue.isEmpty()) return;
     82             mCurrentRequest = mQueue.removeFirst();
     83             mNsdResolveQueue.resolve(mNsdManager, mCurrentRequest.first,
     84                     new NsdManager.ResolveListener() {
     85                 @Override
     86                 public void onResolveFailed(NsdServiceInfo nsdServiceInfo, int i) {
     87                     synchronized (mLock) {
     88                         if (mCurrentRequest != null) mQueue.add(mCurrentRequest);
     89                         makeNextRequest();
     90                     }
     91                 }
     92 
     93                 @Override
     94                 public void onServiceResolved(NsdServiceInfo nsdServiceInfo) {
     95                     synchronized (mLock) {
     96                         if (mCurrentRequest != null) {
     97                             mCurrentRequest.second.serviceResolved(nsdServiceInfo);
     98                             mCurrentRequest = null;
     99                         }
    100                         makeNextRequest();
    101                     }
    102                 }
    103             });
    104 
    105         }
    106     }
    107 
    108 
    109 }
    110