/**
* Synchronization fails for various reasons. Notify the user to retry.
*
* @param msg error message
*/
void notifyRetry(String msg) {
syncHelper.uiHandler.appendToTextView(
syncHelper.instructionView, msg + "\nSynchronization fails. Try again.\n");
syncHelper.startTime = -1;
syncHelper.uiHandler.enableButton(syncHelper.sync, true);
}
@Override
public void run() {
// send out sync pck
byte[] syncPckBytes;
try {
syncPckBytes = new Message(Message.SYNC).toBytes();
DatagramPacket syncPck =
new DatagramPacket(
syncPckBytes, syncPckBytes.length, syncHelper.group, MainActivity.PORT);
syncHelper.ms.send(syncPck);
} catch (JSONException e) {
Log.e(TAG, e.getMessage());
notifyRetry(e.getMessage());
return;
} catch (IOException e) {
Log.e(TAG, e.getMessage());
notifyRetry(e.getMessage());
return;
}
// record start_time
syncHelper.startTime = System.currentTimeMillis();
// wait for ACK
byte[] recvBuf = new byte[512];
DatagramPacket recvPck = new DatagramPacket(recvBuf, recvBuf.length);
try {
syncHelper.ms.setSoTimeout(RECV_TIMEOUT);
} catch (SocketException e1) {
Log.e(TAG, e1.getMessage());
notifyRetry(e1.getMessage());
return;
}
while (true) {
try {
syncHelper.ms.receive(recvPck);
} catch (SocketTimeoutException e) {
// No sync_ack received
notifyRetry("No SYNC_ACK received.");
break;
} catch (IOException e) {
Log.e(TAG, e.getMessage());
notifyRetry(e.getMessage());
break;
}
// check the recv pck
Message recvMsg;
try {
recvMsg = new Message(recvBuf, recvPck.getLength());
if (recvMsg.getInt("type") != Message.SYNC_ACK) {
syncHelper.uiHandler.appendToTextView(
syncHelper.instructionView, "Received non-ACK message.");
continue;
}
// sync_ack successfully received
syncHelper.uiHandler.appendToTextView(
syncHelper.instructionView,
"Synchronization succeeds. "
+ "Press start on both sender and receiver"
+ " to schedule one round's measurement.");
syncHelper.uiHandler.enableButton(syncHelper.start, true);
break;
} catch (JSONException e) {
Log.i(TAG, e.getMessage());
continue;
}
}
}
