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  • How to customize live Ubuntu CD?

    - by karthick87
    I would like to customize Ubuntu live CD by installing some additional packages. I have followed this link but it doesn't seems to work. Can anyone provide clear instructions? Thanks in advance! Customization Packages that I want to install: Thunderbird Samba SSH Changes that I need: Remove Games menu from the Application menu Firefox shortcut on desktop Radiance as the default theme Different default Ubuntu wallpaper Note I do not prefer Remastersys, manual way will be appreciated. updates I want the panel to be placed at the bottom. I want to paste my samba configuration file instead of default samba configuration. And i have few firefox shortcuts and Folders, i have to show that in Desktop. Also it will be nice if you say me how to change the icon sets. Recent Updates I have customized ubuntu 10.10 with firefox shortcuts and few folders on desktops. Everything went smooth. But the installer gets crashes after choosing the timezone. How do i fix this issue? Also setting wallpaper affects the login screen. The wallpaper which i set is displayed on the login screen also. I just want the default one for the login screen.

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  • Creating a shim Stream

    - by spender
    A decompression API that I am using has the following API: Decode(Stream inStream,Stream outStream) I'd like to create a wrapper around this API, such that I can create my own Stream class which offers up the decoded data. Stream decodedStream=new BlaDecodeStream(inStream); So that I can than use this stream as a parameter to the XmlReader constructor in the same way one might use the System.IO.Compression.GZipStream. As far as I can tell, the only other option is set outStream stream to a MemoryStream or to a FileStream and go in two hops. The files I am dealing with are enormous, so neither of these options are particularly attractive. Before I go reinventing the wheel, is there any prior art that I might be able to draw from, or something in the BCL I might have missed? The CircularStream implementation here would go some of the way to helping, but I'm really looking for something similar that would block (as opposed to over/underrun) when the Stream's internal buffer is 'empty' when reading from it and block when the internal buffer is full when writing to it. In this way it could serve as parameter outStream and simultaneously (i.e. from another thread) could be read from by the XmlReader.

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  • x-dom-event-stream in Opera 10 Only Working on First Event

    - by Brad
    I have a python script (in the CherryPy framework) that sends Event: and data: text as this Opera blog post describes to a client browser. The javascript that recieves the x-dom-event-stream content is almost identical to what they show in the blog post. However, the browser displays only the first event sent. Anyone know what I'm missing? I tried a few older versions of Opera and found that it works in Opera 9.52 but not in any newer versions. What did they change? Here is the python code: class dumpData(object): def index(self): cherrypy.response.headers['Content-Type'] = "application/x-dom-event-stream" def yieldData(): i = 0 while 1: yield "Event: count\n" yield "data: " yield i yield "\n\n" i = i + 1 time.sleep(3); return yieldData() index._cp_config = {'response.stream': True} index.exposed = True And here is the javascript/html. Making a request to /data/ runs the python function above. <head> <script> onload = function() { document.getElementById("count").addEventListener("cout", cout, false); } function count(e) { document.getElementById("stream").firstChild.nodeValue = e.data; } </script> <event-source id="count" src="/data/"> </head> <body> <div id="stream"></div> </body> Opening the direct /data/ url in Firefox saves the stream to a file. So I know the output is in the correct format and that the stream works at all.

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  • Why Stream/lazy val implementation using is faster than ListBuffer one

    - by anrizal
    I coded the following implementation of lazy sieve algorithms using Stream and lazy val below : def primes(): Stream[Int] = { lazy val ps = 2 #:: sieve(3) def sieve(p: Int): Stream[Int] = { p #:: sieve( Stream.from(p + 2, 2). find(i=> ps.takeWhile(j => j * j <= i). forall(i % _ > 0)).get) } ps } and the following implementation using (mutable) ListBuffer: import scala.collection.mutable.ListBuffer def primes(): Stream[Int] = { def sieve(p: Int, ps: ListBuffer[Int]): Stream[Int] = { p #:: { val nextprime = Stream.from(p + 2, 2). find(i=> ps.takeWhile(j => j * j <= i). forall(i % _ > 0)).get sieve(nextprime, ps += nextprime) } } sieve(3, ListBuffer(3))} When I did primes().takeWhile(_ < 1000000).size , the first implementation is 3 times faster than the second one. What's the explanation for this ? I edited the second version: it should have been sieve(3, ListBuffer(3)) instead of sieve(3, ListBuffer()) .

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  • Can't play stream from TorrentFlux stream

    - by thegreyspot
    Hi I am trying to stream a video from my TorrentFlux-b4rt server. I tried multiple media players, none work. Only VLC was able to produce an error message: input can't be opened: VLC is unable to open the MRL 'mms://...:8080/'. Check the log for details. I have tried multiple computers on different networks and all have the same issue. I am using Windows 7 to play the videos, and the server is Torrentflux-b4rt 1.0-beta2 with ubuntu 9.10. Thank you.

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  • Implementing a robust async stream reader for a console

    - by Jon
    I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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  • Ubuntu live session crashes and boots to a black screen

    - by Bsc
    I heard about Ubuntu from a friend and wanted to test it out. I made a Pendrive Ubuntu 12.04 with a persistent file using Universal USB Installer. The first time I booted Ubuntu from the USB everything went like usual. I was just a bit exploring Ubuntu and had installed a few apps nothing more. Today after using Windows 7 for while again, I wanted to boot Ubuntu again. When I boot it, the usual loading screen comes up but after that it crashes and gave me a black screen. Is there a possibility to check the USB on errors or do I need to reinstall Ubuntu on the USB?

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  • trying live-usb 12.04.1 image on an old desktop

    - by 213441265152351
    I am trying to load Ubuntu 12.04.1 32-bit desktop image on an old desktop computer. The system shows the initial menu, but after a while, I get an error like the one in the following two screenshots (it takes a few seconds to go from one to the other in the screen): I tried to load it using the different USB ports at the back of the computer, just in case, and I get basically the same error. Find another screenshot from another try: Any ideas what might be happening? NOTES: I checked the md5sum of the iso file to be e235b63c02644e219b7bf3668f479c9e *ubuntu-12.04.1-desktop-i386.iso. I did the 'Test' on the laptop where I created the USB drive, and it loads up correctly. The desktop computer in question is an old AMD Duron 1800MHz with 512MB RAM. I ran a memtest on the computer, and all went fine.

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  • Creating a live CD with pre installed users

    - by juzerali
    I want to create my own customized Ubuntu derivative and this question already gave me a very good start. My requirements are quite specific I want to roll out a CD with Set of users who are supposed to run them (root, admin, guest) pre-installed With their passwords already set Installation not asking for creating users on booting or during OS installation Autologin to guest user Is this even possible? Thanks to the community in advance :)

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  • Ubuntu 12.10 Live USB BootError

    - by Sivan
    I am a Linux Newbee, running ubuntu 12.04 i386 on a 64-bit machine. Now I just downloaded Ubuntu 12.10 AMD64 iso and made a bootable USB using Startup Disk Creator. I was directed to install available updated packages, which I did install. The Startup Disk was succesfully created. But when I tried to boot from the USB I am getting a BootError message and nothing else. What could have gone wrong?

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  • Not able to create Live CD

    - by Jagannath Harati
    I downloaded 12.04.1 on a Windows 7 machine. I burnt a DVD from the ISO image using Windows Disc Image Burner. I had 'verify disc' on. The disc was created successfully with no errors. I was not able to use this disc for installing Ubuntu on another Windows 7 machine. I do not get the Welcome Screen on booting. I find that on the disc I burnt, I do not find bin, disc tree, programs directories and cdromupgrade, start.*, ubuntu* files. I found the boot directory and WUBI executable file. I tried downloading several times with the same result. I had similar problem earlier with 11.04. Can you please let me where the problem is?

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  • Can't boot from Ubuntu 12.04 live USB

    - by 8vius
    I'm trying to recover GRUB after installing Windows 7. I installed Ubuntu 12.04 first, then installed Windows 7 so I lost the GRUB at startup. Made a USB stick with Ubuntu to boot from, I get the menu tell it to start and it takes off but then gets stuck. The last line showing on the screen is: ata10: PATA max UDMA/100 cmd 0xc800 ctl 0xc480 irq 17 or this: [4.793048] scsi9 : pata_jmicron Then it just gets stuck there and the screen flashes from time to time.

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  • Recording slow web stream

    - by Budric
    I'm trying to record an mpeg2 video stream from a website that doesn't have the greatest bandwidth. The video often buffers. I want to download the stream and watch it offline. The extract stream format received is: Stream #0.0[0x44]: Audio: mp2, 48000 Hz, stereo, s16, 192 kb/s Stream #0.1[0x45]: Video: mpeg2video (Main), yuv420p, 704x576 [PAR 16:11 DAR 16:9], 15000 kb/s, 27.19 fps, 25 tbr, 90k tbn, 50 tbc I use the following tool to transocde the stream: ffmpeg -i "http://url" -y -vcodec libx264 -b 3000k -acodec copy /tmp/stream.mp4 Unfortunately after a few seconds ffmpeg stops recording with an error [mpegts @ 0x1f0b9c0] PES packet size mismatch [mp2 @ 0x1f14640] incomplete frame Error while decoding stream #0.0 [mpeg2video @ 0x1f16860] ac-tex damaged at 0 26 [mpeg2video @ 0x1f16860] Warning MVs not available I've tried encoding with vlc as well with similar issues. Although vlc doesn't stop encoding, the output video has regions where it hangs. vlc -I dummy "http://url" --network-caching="1000" --sout="#transcode{vcodec=h264,vb=3000,acodec=mp3,ab=192}:std{access=file,mux=mp4,dst=/tmp/stream.mp4}" [mpeg2video @ 0x7f2d4c001e20] ac-tex damaged at 9 33 [mpeg2video @ 0x7f2d4c001e20] Warning MVs not available [mpeg2video @ 0x7f2d4c001e20] concealing 132 DC, 132 AC, 132 MV errors [mpeg2video @ 0x7f2d4c001e20] ac-tex damaged at 16 17 [mpeg2video @ 0x7f2d4c001e20] Warning MVs not available [mpeg2video @ 0x7f2d4c001e20] concealing 836 DC, 836 AC, 836 MV errors libdvbpsi error (PSI decoder): TS discontinuity (received 4, expected 3) for PID 0 I also tried flv transcoding and it shows up with its own set of issues, like output flv file hangs in certain parts. Anyone know what's wrong or how to fix this?

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  • Writing String to Stream and reading it back does not work

    - by Binary255
    I want to write a String to a Stream (a MemoryStream in this case) and read the bytes one by one. stringAsStream = new MemoryStream(); UnicodeEncoding uniEncoding = new UnicodeEncoding(); String message = "Message"; stringAsStream.Write(uniEncoding.GetBytes(message), 0, message.Length); Console.WriteLine("This:\t\t" + (char)uniEncoding.GetBytes(message)[0]); Console.WriteLine("Differs from:\t" + (char)stringAsStream.ReadByte()); The (undesired) result I get is: This: M Differs from: ? It looks like it's not being read correctly, as the first char of "Message" is 'M', which works when getting the bytes from the UnicodeEncoding instance but not when reading them back from the stream. What am I doing wrong? The bigger picture: I have an algorithm which will work on the bytes of a Stream, I'd like to be as general as possible and work with any Stream. I'd like to convert an ASCII-String into a MemoryStream, or maybe use another method to be able to work on the String as a Stream. The algorithm in question will work on the bytes of the Stream.

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  • Windows Live Writer fails to start

    - by Albert Bori
    I installed windows live writer and configured it to connect to my xmlrpc enabled blog engine. After doing so, it threw an unrecoverable error and closed down. After attempting to restart windows live writer, it throws the following exception each time: Description: Windows Live Writer has encountered a problem: Invalid URI: The hostname could not be parsed. Problem signature: Problem Event Name: WindowsLiveWriter Problem Signature 01: CreateThis Problem Signature 02: 115 Problem Signature 03: System.UriFormatException Problem Signature 04: 15.4.3555.308 Problem Signature 05: 2.0.50727.5456 Problem Signature 06: Windows Live Writer OS Version: 6.1.7601.2.1.0.256.1 Locale ID: 1033 Since I was unable to start windows live writer at all, I tried uninstalling it and removing all files associated with it in my "C:/users/[username]/appdata" folder. After that, I re-installed it and still get the error every time I try to launch the application. Does anyone know how I can get around this?

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  • Implementing an async "read all currently available data from stream" operation

    - by Jon
    I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a console's standard output Stream. Console output streams are of type FileStream; the implementation can cast to that, if needed. There is also an associated StreamReader already present to leverage. There is only one thing I need to implement in this class to achieve my desired functionality: an async "read all the data available this moment" operation. Reading to the end of the stream is not viable because the stream will not end unless the process closes the console output handle, and it will not do that because it is interactive and expecting input before continuing. I will be using that hypothetical async operation to implement event-based notification, which will be more convenient for my callers. The public interface of the class is this: public class ConsoleAutomator { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Remember that the goal here is to read all of the chunk and call event subscribers exactly once for each chunk. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream. private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer (in which case we know that there was no more data to be read during the last read operation), all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Never more than one event for each time data is available to be read Is almost agnostic to the buffer size The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this. Update: I definitely did not communicate the scenario well in my initial writeup. I have since revised the writeup quite a bit, but to be extra sure: The question is about how to implement an async "read all the data available this moment" operation. My apologies to the people who took the time to read and answer without me making my intent clear enough.

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  • Implementing a robust async stream reader

    - by Jon
    I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output, but that is a detail and does not play an important role. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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  • Stream classes ... design, pattern for creating views over streams

    - by ToxicAvenger
    A question regarding the design of stream classes - I need a pattern to create independent views over a single stream instance (in my case for reading). A view would be a consecutive part of the stream. The problem I have with the stream classes is that the state (reading or writing) is coupled with the underlying data/storage. So if I need to partition a stream into different segments (whether segments overlap or not doesn't matter), I cannot easily create views over the stream, the views would store start and end position. Because reading from a view - which would translate to reading from the underlying stream adjusted based on the start/end positions - would change the state of the underlying stream instance. So what I could do is take a read on a view instance, adjust the Position of the stream, read the chunks I need. But I cannot do that concurrently. Why is it designed in such a way, and what kind of pattern could I implement to create independet views over a single stream instance which would allow to read/write independently (and concurrently)?

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  • ffmpeg, vlc - Unable to find input stream

    - by zozo
    Good day to all... I have some "little" problems with ffserver and ffmpeg... What I need to do is to broadcast a live video. So I got the cam... used vlc and used send stream option. I sent it to 192.168.1.9:64555, which is a virtual machine on the same computer, running centos. On the virtual machine I run the command ffmpeg -i 192.168.1.9:64555 output.mpg. The response is "unable to find file whatever". Can any1 tell me what I did wrong? Thank you and have a great day. Print-screen with error:

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  • How to find other end of unix socket connection?

    - by depesz
    I have a process (dbus-daemon) which has many open connection over UNIX sockets. One of these connections is fd #36: =$ ps uw -p 23284 USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND depesz 23284 0.0 0.0 24680 1772 ? Ss 15:25 0:00 /bin/dbus-daemon --fork --print-pid 5 --print-address 7 --session =$ ls -l /proc/23284/fd/36 lrwx------ 1 depesz depesz 64 2011-03-28 15:32 /proc/23284/fd/36 -> socket:[1013410] =$ netstat -nxp | grep 1013410 (Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.) unix 3 [ ] STREAM CONNECTED 1013410 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD =$ netstat -nxp | grep dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013953 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013825 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013726 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013471 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1013410 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012325 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012302 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012289 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1012151 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011957 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011937 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011900 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011775 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011771 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011769 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011766 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011663 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011635 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011627 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011540 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011480 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011349 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011312 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011284 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011250 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011231 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011155 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011061 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011049 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011035 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1011013 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1010961 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD unix 3 [ ] STREAM CONNECTED 1010945 23284/dbus-daemon @/tmp/dbus-3XDU4PYEzD Based on number connections, I assume that dbus-daemon is actually server. Which is OK. But how can I find which process is connected to it - using the connection that is 36th file handle in dbus-launcher? Tried lsof and even greps on /proc/net/unix but I can't figure out a way to find the client process.

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  • Booting the liveCD/USB in EFI mode fails on Samsung Tablet XE700T1A

    - by F.L.
    My tablet is Samsung Series 7 Slate (XE700T1A-A02FR (French Language)). It operates an Intel Sandy Bridge architecture. The main issue about this tablet is that it ships with an installed Windows 7 in (U)EFI mode (GPT partition table, etc.), so I'd like to get an EFI dual boot with Ubuntu. But it seems I can't boot on the liveCD in EFI mode. It starts loading (up to initrd), but I then get a blank (black) screen. I've tried the nomodeset kernel option (as well as removing quiet and splash) with no luck. [2012-09-27] I have used the Ubuntu 12.04.1 Desktop ISO (I have read somewhere that it is the only one that can boot in EFI mode). I'd say this has something to do with UEFI since the LiveCD boots in bios mode but not in efi mode. Besides, I am not sure my boot info will help, since I can't boot the LiveCD in EFI mode. As a result I can't install ubuntu in EFI mode. So it would be the boot info from the liveCD boot in bios mode. This happens on a ubuntu-12.04.1-desktop-amd64 iso used on a LiveUSB. Live USB was created by dd'ing the iso onto the full disk device (i.e. /dev/sdx no number) of the Flash drive. I have also tried copying the LiveCD files on a primary GPT partition, but with no luck, I just get the grub shell, no menu, no install option. [2012-09-28] I tried today a flash drive created with Ubuntu's Startup Disk Creator and the alternate 12.04.1 64 bit ISO. I get a grub menu in text mode (which meens it did start in efi mode) with install options / test options. But when I start any of these, I simply get a black screen (no cursor, neither mouse nor text-mode cursor). I tried removing the 'quiet' option and adding nomodeset and acpi=off, but it didn't do any good. So this is the same result as for the LiveCD. [2012-10-01] I have tried with a version of the secure remix version via usb-creator-gtk. The boot on the USB key has the same symptoms. Boot in EFI mode is impossible (I have menu but whatever entry I choose, I get the blank screen problem). The boot in BIOS mode works, I did the install. Then I used boot-repair to try installing grub-efi and get a system that would boot in efi mode. But I can't boot this system, because the EFI firmware doesn't seem to detect that sda contains a valid efi partition. Here is the resulting boot-info Boot info 1253554 [2012-10-01] Today, I have reinstalled the pre-shipped version of windows 7, and then installed ubuntu from a secure-remix iso dumped on USB flash drive vie usb-creator-gtk booted in BIOS mode. When install ended, I said "continue testing" then I used boot-repair to try get the bootloader installed. Now, when I boot the tablet, I get the grub menu, it can chainload windows 7 flawlessly. But when I try to start one of the ubuntu options I get the same old blank screen. Here is the new boot-info: Boot info 1253927 [2012-10-01] I tried installing the 3.3 kernel by chrooting a live usb boot (secure remix again) into the installed system. Same symptoms. I feel the key to this is that the device's efi firmware (which is EFI v2.0) would expose the graphics hardware in a way that prevents the kernel to initialize it, and thus prevents it from booting (the kernel stops all drive access just after the screen turns kind of very dark purple). Here is some info on the UEFI firmware as given by rEFInd: EFI revision: 2.00 Platform: x86_64 (64 bit) Firmware: American Megatrends 4.635 Screen Output: Graphics Output (UEFI), 800x600 [2012-10-08] This week end I tried loading the kernel with elilo. Eventhough I didn't have more luck on booting the kernel, elilo gives more info when loading the kernel. I think the next step is trying to load a kernel with EFI stub directly.

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  • Stream data with Node.js

    - by Saif Bechan
    I want to know if it is possible to stream data from the server to the client with Node.js. From what I can understand all over the internet is that this has to be possible, yet I fail to find a correct example or solution. What I want is a single http post to node.js with AJAX. Than leave the connection open and continuously stream data to the client. The client will receive this stream and update the page continuously.

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  • Concepts: Channel vs. Stream

    - by hotzen
    Hello, is there a conceptual difference between the terms "Channel" and "Stream"? Do the terms require/determine, for example, the allowed number of concurrent Consumers or Producers? I'm currently developing a Channel/Stream of DataFlowVariables, which may be written by one producer and read by one consumer as the implementation is destructive/mutable. Would this be a Channel or Stream, is there any difference at all? Thanks

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  • Does isEmpty method in Stream evaluate the whole Stream?

    - by abhin4v
    In Scala, does calling isEmtpy method on an instance of Stream class cause the stream to be evaluated completely? My code is like this: import Stream.cons private val odds: Stream[Int] = cons(3, odds.map(_ + 2)) private val primes: Stream[Int] = cons(2, odds filter isPrime) private def isPrime(n: Int): Boolean = n match { case 1 => false case 2 => true case 3 => true case 5 => true case 7 => true case x if n % 3 == 0 => false case x if n % 5 == 0 => false case x if n % 7 == 0 => false case x if (x + 1) % 6 == 0 || (x - 1) % 6 == 0 => true case x => primeDivisors(x) isEmpty } import Math.{sqrt, ceil} private def primeDivisors(n: Int) = primes takeWhile { _ <= ceil(sqrt(n))} filter {n % _ == 0 } So, does the call to isEmpty on the line case x => primeDivisors(x) isEmpty cause all the prime divisors to be evaluated or only the first one?

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