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    <p>Okay, so I tried to create a Fast A and AB and then a slow B. This means that my overall time is slower (mainly because of the b-only stream), but the combined time and a-only time is faster. Here are the results:</p> <pre><code>A's only: 00:00:00.3975499 Combine: 00:00:00.4234934 B's only: 00:00:02.0079422 Total: 00:00:02.8314751 0: 0 A: 700 B: 200 AB: 100 Generated A: 800, Sent A: 800 Generated B: 300, Sent B: 300 </code></pre> <p>Here's the code:</p> <pre><code> class MessageWrapper { object bMessageLock = new object(); object pendingBLock = new object(); int? pendingB; ManualResetEvent gateOpen = new ManualResetEvent(true); // Gate is open initially. private bool IsGateOpen() { return gateOpen.WaitOne(0); } private void OpenGate() { gateOpen.Set(); } private void CloseGate() { gateOpen.Reset(); } public Message WrapA(int a, int millisecondsTimeout) { // check if the gate is open. Use WaitOne(0) to return immediately. if (IsGateOpen()) { return new Message(a, null); } else { // This extra lock is to make sure that we don't get stale b's. lock (pendingBLock) { // and reopen the gate. OpenGate(); // there is a waiting b // Send combined message var message = new Message(a, pendingB); pendingB = null; return message; } } } public Message WrapB(int b, int millisecondsTimeout) { // Remove this if you don't have overlapping B's var timespentInLock = Stopwatch.StartNew(); lock (bMessageLock) // Only one B message can be sent at a time.... may need to fix this. { pendingB = b; // Close gate CloseGate(); // Wait for the gate to be opened again (meaning that the message has been sent) if (timespentInLock.ElapsedMilliseconds &lt; millisecondsTimeout &amp;&amp; gateOpen.WaitOne(millisecondsTimeout - (int)timespentInLock.ElapsedMilliseconds)) // If you don't have overlapping b's use this clause instead. //if (gateOpen.WaitOne(millisecondsTimeout)) { lock (pendingBLock) { // Gate was opened, so combined message was sent. return null; } } else { // Timeout expired, so send b-only message. lock (pendingBLock) { // reopen gate. OpenGate(); pendingB = null; return new Message(null, b); } } } } } </code></pre> <p>The main work is done my using a manual reset event. The idea is that if the gate is open, then you can send A's freely. When a 'b' arrives, you close the gate and force A to combine it. I must say that having a single <code>pendingB</code> field restricts this operation somewhat. Having only one variable means that only one thread can store it's b in pendingB. This is why I have the extra <code>bMessageLock</code>. </p> <p>Also, access to this variable needs to be controlled, hence the <code>pendingBLock</code>.</p> <p>There may still be bugs in this code, but as much as I test it, I still get all 100 messages combined.</p> <p>Lastly, I included the check against the time that WrapB was waiting. Originally the WrapB's would just queue up taking a total of 200 seconds. If you have overlapping calls, then you can add the check. If you don't mind them queuing up, use the simpler code instead.</p>
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    1. POImprove efficiency and fairness when combining temporally close events
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