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buffering algorithm

Posted on 2013-12-06
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Last Modified: 2013-12-07
Hi Experts,
I have been struggling for days now how to solve this problem  and couldn't get it right.
Here is the problem:
I receive startPlay command | stopPlay command from the User Interface layer
every command contains a code so e.g.
at 10.33 I receive startPlay (#1)
after 100 ms I receive stopPlay()
I calculate the duration = diff between start time and stop time and send that to network using some protocol.
Then I receive second command and third command etc...
in order to have those commands working at the network side, the duration should be at least 85 ms and the spacing between command e.g command1 and command2 needs to be 45 ms.
There is some delay at the UI layer ( that I cannot control), so sometimes I receive the start command and stop command too short (less than 85 ms), sometimes the gap between command1 and command 2 is less than 45 sec.
I tried to write a buffering algorithm to solve that delay so I can raise the duration to 85 ms if it is less than that and same for the time between stopping first command and starting  the next one.
As of yet I could n't get it working right and came here to seek your advice how to approach this problem.
I thought about having two queues one for the start command and one for the stop command
and a Timer when it kicks check the first queue and run the command then after some time check the second queue and run the stop command but I'm still not clear how to solve it right.
I'm pretty sure this kind of problems was already solved.
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Question by:bachra04
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dpearson earned 500 total points
ID: 39703899
Something like this might do it for you?

private ExecutorService m_Executor = Executors.newFixedThreadPool(1) ;

// For a start
m_Executor.execute(new Runnable() {			
	public void run() {
              long startTime = System.currentTimeMillis() ;
              startPlay() ;
              long elapsed = System.currentTimeMillis() - startTime ;
              long timeToSleepMs = Math.Max(85-elapsed, 0) ;
              sleep(timeToSleepMs) ;
	}
}) ;

// For a stop
m_Executor.execute(new Runnable() {			
	public void run() {
            stopPlay() ;
	}
}) ;

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The idea is to handle the start and stops on a separate thread.  So you can add a sleep() into the start logic making sure the start call takes at least 85 ms.
As the stop is executed on the same thread, it will wait for the first sleep to finish before executing.

However, your thread can continue to receive these and add them to the executor as quickly as you like - they'll just build up and execute in order for you.  So you don't block the UI as it calls to you.

Any help?

Doug
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LVL 2

Author Closing Comment

by:bachra04
ID: 39703947
Now I just need to code it in C/C++ with pthread.
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