nonblocking | 易学教程

How to make sure a dialog is always front of the main window

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问题 I have not yet found the best solution for this. I have a non modal dialog that can be opened in unlimited instances by a hotkey in the application. Even the dialog itself can open a new instance. I want those dialogs to always be front of the main application window. I have tried a couple of things. Set FormStyle to fsStayOntop. This works but have the advantage that the dialog will be front of ALL windows even other applications. I only want it to be front of my main window. Set PopupMode

C /C++ Lock-free (or nonblocking) Ring Buffer that OVERWRITES oldest data?

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I'm trying to find a way to make a Lock Free OR Non-blocking way to make a Ring Buffer for single consumer / single consumer that will over-write the oldest data int the buffer. I've read a lot of lock-free algorithms that work when you "return false" if the buffer is full--ie, don't add; but I can't find even pseudo-code that talks about how to do it when you need to overwrite the oldest data. I am using GCC 4.1.2 (restriction at work, i can't upgrade the version...) and I have the Boost libraries, and in the past I made my own Atomic< T > variable type that follows pretty closely to the

How to do non blocking socket reads with Protobuf using C#?

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问题 Lets say I want to do non blocking reads from a network socket. I can async await for the socket to read x bytes and all is fine. But how do I combine this with deserialization via protobuf? Reading objects from a stream must be blocking? that is, if the stream contains too little data for the parser, then there has to be some blocking going on behind the scenes so that the reader can fetch all the bytes it needs. I guess I can use lengthprefix delimiters and read the first bytes and then

How is event driven programming implemented?

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问题 I was looking on how the twisted and node.js frameworks work and I am trying to understand exactly how the operating system supports I/O operations using callbacks. I understand it's good because we need less threads because we don't need to have blocked threads waiting for I/O operations. But something has to call the callback once the I/O is finished. How is this implemented by the operating system? 回答1: One approach is to have the OS attach information about anyone waiting for a callback

How does the UV_RUN_NOWAIT mode work in libuv?

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问题 When running an event loop in libuv using the uv_run function, there's a "mode" parameter that is used with the following values: UV_RUN_DEFAULT UV_RUN_ONCE UV_RUN_NOWAIT The first two are obvious. UV_RUN_DEFAULT runs the event loop until there are no more events, and UV_RUN_ONCE processing a single event from the loop. However, UV_RUN_NOWAIT doesn't seem to be a separate mode, but rather a flag that can be ORed with one of the other two values. By default, this function blocks until events

Cross-platform (linux/Win32) nonblocking C++ IO on stdin/stdout/stderr

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问题 I'm trying to find the best solution for nonblocking IO via stdin/stdout with the following characteristics: As long as there is enough data, read in n -sized chunks. If there's not enough data, read in a partial chunk. If there is no data available, block until there is some (even though it may be smaller than n ). The goal is to allow efficient transfer for large datasets while processing 'control' codes immediately (instead of having them linger in some partially-filled buffer somewhere).

How to make non-blocking raw_input when using eventlet.monkey_patch() and why it block everything, even when executed on another thread?

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I wrote this minimum code to explain my case: import threading import time import eventlet eventlet.monkey_patch() def printing_function(): while True: # here i want to do some work print "printing" time.sleep(1) if __name__ == '__main__': thread = threading.Thread(target=printing_function) thread.start() while True: # here i want to wait for users input raw_input("raw input\n") print "inside main loop" time.sleep(1) Even i have 2 threads, both of them are blocked when i call raw_input. When i comment out eventlet.monkey_patch(), only one thread is blocked and another keep printing "printing".

Should I use (non-blocking) NIO for UDP?

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According to this post , UDP just doesn't block. Are there any advantage using the (non-blocking) NIO API for UDP? Or should I just use the easier "traditional" io API? At the risk of just pointing you back, the comments to that post explain that UDP doesn't block on the TCP ACK, but you could still block on a kernel buffer overflow. This would happen only if you have a very big UDP burst. If you are working with a large number of streams, it may help you to have a dedicate threading model to handle those sockets. NIO provides some of the work (selectors) that would help. 来源： https:/

Waiting for multiple results in Akka

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问题 What is the proper way to wait for the result of multiple actors in Akka? The Principles of Reactive Programming Coursera course had an exercise with a replicated key-value store. Without going into the details of the assignment, it required waiting on the acknowledgement of multiple actors before it could indicate the replication was complete. I implemented the assignment using a mutable map containing the outstanding requests, but I felt the solution had a 'bad smell'. I hoped there was a

Context Switches on Sleeping/Waiting Threads

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问题 I'm trying to understand how operating systems handle context switching in different models to better understand why NIO performance is better in cases of large peaks in the number of requests. Apart from the fact that there may be a limit to the number of threads, I'm curious how blocking operations being done in those large number of requests can affect resource utilization. In a one request per thread model, say a servlet 2.5 based web application, if 499 threads are waiting for database