1 files changed, 101 insertions, 0 deletions
diff --git a/PrinterRecommendationExample/app/src/main/java/com/android/discovery/recommendation/ServiceResolveQueue.java b/PrinterRecommendationExample/app/src/main/java/com/android/discovery/recommendation/ServiceResolveQueue.java
new file mode 100644
index 0000000..cdfd937
--- /dev/null
+++ b/PrinterRecommendationExample/app/src/main/java/com/android/discovery/recommendation/ServiceResolveQueue.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package com.android.discovery.recommendation;
+
+import android.net.nsd.NsdManager;
+import android.net.nsd.NsdServiceInfo;
+import android.util.Pair;
+
+import java.util.LinkedList;
+
+public final class ServiceResolveQueue {
+
+    private final NsdManager mNsdManager;
+    private final LinkedList<Pair<NsdServiceInfo, ResolveCallback>> mQueue = new LinkedList<>();
+    private final Object mLock = new Object();
+
+    private static ServiceResolveQueue sInstance = null;
+    private Pair<NsdServiceInfo, ResolveCallback> mCurrentRequest = null;
+
+    public static void createInstance(NsdManager nsdManager) {
+        if (sInstance == null) sInstance = new ServiceResolveQueue(nsdManager);
+    }
+
+    public static ServiceResolveQueue getInstance() {
+        return sInstance;
+    }
+
+    public static void destroyInstance() {
+        sInstance = null;
+    }
+
+    public interface ResolveCallback {
+        void serviceResolved(NsdServiceInfo nsdServiceInfo);
+    }
+
+    public ServiceResolveQueue(NsdManager nsdManager) {
+        mNsdManager = nsdManager;
+    }
+
+    public void queueRequest(NsdServiceInfo serviceInfo, ResolveCallback callback) {
+        synchronized (mLock) {
+            Pair<NsdServiceInfo, ResolveCallback> newRequest = Pair.create(serviceInfo, callback);
+            if (mQueue.contains(newRequest)) return;
+            mQueue.add(newRequest);
+            makeNextRequest();
+        }
+    }
+
+    public void removeRequest(NsdServiceInfo serviceInfo, ResolveCallback callback) {
+        synchronized (mLock) {
+            Pair<NsdServiceInfo, ResolveCallback> newRequest = Pair.create(serviceInfo, callback);
+            mQueue.remove(newRequest);
+            if ((mCurrentRequest != null) && newRequest.equals(mCurrentRequest)) mCurrentRequest = null;
+        }
+    }
+
+    private void makeNextRequest() {
+        synchronized (mLock) {
+            if (mCurrentRequest != null) return;
+            if (mQueue.isEmpty()) return;
+            mCurrentRequest = mQueue.removeFirst();
+            mNsdManager.resolveService(mCurrentRequest.first, new NsdManager.ResolveListener() {
+                @Override
+                public void onResolveFailed(NsdServiceInfo nsdServiceInfo, int i) {
+                    synchronized (mLock) {
+                        if (mCurrentRequest != null) mQueue.add(mCurrentRequest);
+                        makeNextRequest();
+                    }
+                }
+
+                @Override
+                public void onServiceResolved(NsdServiceInfo nsdServiceInfo) {
+                    synchronized (mLock) {
+                        if (mCurrentRequest != null) {
+                            mCurrentRequest.second.serviceResolved(nsdServiceInfo);
+                            mCurrentRequest = null;
+                        }
+                        makeNextRequest();
+                    }
+                }
+            });
+
+        }
+    }
+
+
+}