add a queue of Threads (aka channelWaitingQueue) that will be awake w…

…hen the channel is ready
paolosanchi · Feb 11, 2021 · 617c7ba · 617c7ba
1 parent 04f971f
commit 617c7ba
Showing 1 changed file with 25 additions and 1 deletion.
diff --git a/src/android/src/com/chariotsolutions/nfc/plugin/NfcPlugin.java b/src/android/src/com/chariotsolutions/nfc/plugin/NfcPlugin.java
@@ -79,6 +79,7 @@ public class NfcPlugin extends CordovaPlugin implements NfcAdapter.OnNdefPushCom
     private static final String TAG = "NfcPlugin";
     private final List<IntentFilter> intentFilters = new ArrayList<>();
     private final ArrayList<String[]> techLists = new ArrayList<>();
+    private final ArrayList<Thread> channelWaitingQueue = new ArrayList<>();
 
     private NdefMessage p2pMessage = null;
     private PendingIntent pendingIntent = null;
@@ -105,6 +106,7 @@ public boolean execute(String action, JSONArray data, CallbackContext callbackCo
         // the channel is set up when the plugin starts
         if (action.equalsIgnoreCase(CHANNEL)) {
             channelCallback = callbackContext;
+            awakeChannelWaitingQueue();
             return true; // short circuit
         }
 
@@ -197,6 +199,13 @@ public boolean execute(String action, JSONArray data, CallbackContext callbackCo
         return true;
     }
 
+    private void awakeChannelWaitingQueue() {
+        for (Thread t: channelWaitingQueue) {
+            t.interrupt();
+        }
+        channelWaitingQueue.clear();
+    }
+
     private String getNfcStatus() {
         NfcAdapter nfcAdapter = NfcAdapter.getDefaultAdapter(getActivity());
         if (nfcAdapter == null) {
@@ -737,14 +746,29 @@ private void sendEvent(String type, JSONObject tag) {
 
             PluginResult result = new PluginResult(PluginResult.Status.OK, event);
             result.setKeepCallback(true);
-            while(channelCallback == null) { }
+            waitForChannel();
             channelCallback.sendPluginResult(result);
         } catch (JSONException e) {
             Log.e(TAG, "Error sending NFC event through the channel", e);
         }
 
     }
 
+    private void waitForChannel() {
+        if(channelCallback == null) {
+            channelWaitingQueue.add(Thread.currentThread());
+
+            while (channelCallback == null) {
+                try {
+                    Thread.sleep(1000);
+                } catch (InterruptedException ie) {
+                    // the thread has been awakened, so channelCallback is set
+                    return;
+                }
+            }
+        }
+    }
+
     private void fireNdefEvent(String type, Ndef ndef, Parcelable[] messages) {
         JSONObject json = buildNdefJSON(ndef, messages);
         sendEvent(type, json);