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  • Instantiating class with custom allocator in shared memory

    - by recipriversexclusion
    I'm pulling my hair due to the following problem: I am following the example given in boost.interprocess documentation to instantiate a fixed-size ring buffer buffer class that I wrote in shared memory. The skeleton constructor for my class is: template<typename ItemType, class Allocator > SharedMemoryBuffer<ItemType, Allocator>::SharedMemoryBuffer( unsigned long capacity ){ m_capacity = capacity; // Create the buffer nodes. m_start_ptr = this->allocator->allocate(); // allocate first buffer node BufferNode* ptr = m_start_ptr; for( int i = 0 ; i < this->capacity()-1; i++ ) { BufferNode* p = this->allocator->allocate(); // allocate a buffer node } } My first question: Does this sort of allocation guarantee that the buffer nodes are allocated in contiguous memory locations, i.e. when I try to access the n'th node from address m_start_ptr + n*sizeof(BufferNode) in my Read() method would it work? If not, what's a better way to keep the nodes, creating a linked list? My test harness is the following: // Define an STL compatible allocator of ints that allocates from the managed_shared_memory. // This allocator will allow placing containers in the segment typedef allocator<int, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef SharedMemoryBuffer<int, ShmemAllocator> MyBuf; int main(int argc, char *argv[]) { shared_memory_object::remove("MySharedMemory"); //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a buffer named "MyBuffer" in shared memory with argument alloc_inst MyBuf *pBuf = segment.construct<MyBuf>("MyBuffer")(100, alloc_inst); } This gives me all kinds of compilation errors related to templates for the last statement. What am I doing wrong?

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  • Segmentation in Linux : Segmentation & Paging are redundant?

    - by claws
    Hello, I'm reading "Understanding Linux Kernel". This is the snippet that explains how Linux uses Segmentation which I didn't understand. Segmentation has been included in 80 x 86 microprocessors to encourage programmers to split their applications into logically related entities, such as subroutines or global and local data areas. However, Linux uses segmentation in a very limited way. In fact, segmentation and paging are somewhat redundant, because both can be used to separate the physical address spaces of processes: segmentation can assign a different linear address space to each process, while paging can map the same linear address space into different physical address spaces. Linux prefers paging to segmentation for the following reasons: Memory management is simpler when all processes use the same segment register values that is, when they share the same set of linear addresses. One of the design objectives of Linux is portability to a wide range of architectures; RISC architectures in particular have limited support for segmentation. All Linux processes running in User Mode use the same pair of segments to address instructions and data. These segments are called user code segment and user data segment , respectively. Similarly, all Linux processes running in Kernel Mode use the same pair of segments to address instructions and data: they are called kernel code segment and kernel data segment , respectively. Table 2-3 shows the values of the Segment Descriptor fields for these four crucial segments. I'm unable to understand 1st and last paragraph.

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  • C# Collision Math Help

    - by user36037
    I am making my own collision detection in MonoGame. I have a PolyLine class That has a property to return the normal of that PolyLine instance. I have a ConvexPolySprite class that has a List LineSegments. I hav a CircleSprite class that has a Center Property and a Radius Property. I am using a static class for the collision detection method. I am testing it on a single line segment. Vector2(200,0) = Vector2(300, 200) The problem is it detects the collision anywhere along the path of line out into space. I cannot figure out why. Thanks in advance; public class PolyLine { //--------------------------------------------------------------------------------------------------------------------------- // Class Properties /// <summary> /// Property for the upper left-hand corner of the owner of this instance /// </summary> public Vector2 ParentPosition { get; set; } /// <summary> /// Relative start point of the line segment /// </summary> public Vector2 RelativeStartPoint { get; set; } /// <summary> /// Relative end point of the line segment /// </summary> public Vector2 RelativeEndPoint { get; set; } /// <summary> /// Property that gets the absolute position of the starting point of the line segment /// </summary> public Vector2 AbsoluteStartPoint { get { return ParentPosition + RelativeStartPoint; } }//end of AbsoluteStartPoint /// <summary> /// Gets the absolute position of the end point of the line segment /// </summary> public Vector2 AbsoluteEndPoint { get { return ParentPosition + RelativeEndPoint; } }//end of AbsoluteEndPoint public Vector2 NormalizedLeftNormal { get { Vector2 P = AbsoluteEndPoint - AbsoluteStartPoint; P.Normalize(); float x = P.X; float y = P.Y; return new Vector2(-y, x); } }//end of NormalizedLeftNormal //--------------------------------------------------------------------------------------------------------------------------- // Class Constructors /// <summary> /// Sole ctor /// </summary> /// <param name="parentPosition"></param> /// <param name="relStart"></param> /// <param name="relEnd"></param> public PolyLine(Vector2 parentPosition, Vector2 relStart, Vector2 relEnd) { ParentPosition = parentPosition; RelativeEndPoint = relEnd; RelativeStartPoint = relStart; }//end of ctor }//end of PolyLine class public static bool Collided(CircleSprite circle, ConvexPolygonSprite poly) { var distance = Vector2.Dot(circle.Position - poly.LineSegments[0].AbsoluteEndPoint, poly.LineSegments[0].NormalizedLeftNormal) + circle.Radius; if (distance <= 0) { return false; } else { return true; } }//end of collided

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  • Xen won't start after it had been working

    - by Paul Tomblin
    I've been setting up this Debian Stable system with a dom0 and 3 domUs. It was working fine for several days, and I'm almost ready to deploy it to the rack. But last night I shut it down with all three domUs still running for the first time, and today when I started it up, xend won't start. In /var/log/messages, I have: Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: blktapctrl: v1.0.0 Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Found driver: [raw image (aio)] Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Found driver: [raw image (sync)] Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Found driver: [vmware image (vmdk)] Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Found driver: [ramdisk image (ram)] Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Found driver: [qcow disk (qcow)] Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: couldn't find device number for 'blktap0' Apr 18 13:01:33 xen-test BLKTAPCTRL[4248]: Unable to start blktapctrl and in /var/log/xen/xend.log, I have this: [2010-04-18 12:46:32 3523] INFO (SrvDaemon:219) Xend exited with status 1. [2010-04-18 13:01:34 4255] INFO (SrvDaemon:331) Xend Daemon started [2010-04-18 13:01:34 4255] INFO (SrvDaemon:335) Xend changeset: unavailable. [2010-04-18 13:01:34 4255] INFO (SrvDaemon:342) Xend version: Unknown. [2010-04-18 13:01:34 4255] ERROR (SrvDaemon:353) Exception starting xend (no element found: line 1, column 0) Traceback (most recent call last): File "/usr/lib/xen-3.2-1/lib/python/xen/xend/server/SrvDaemon.py", line 345, in run servers = SrvServer.create() File "/usr/lib/xen-3.2-1/lib/python/xen/xend/server/SrvServer.py", line 251, in create root.putChild('xend', SrvRoot()) File "/usr/lib/xen-3.2-1/lib/python/xen/xend/server/SrvRoot.py", line 40, in __init__ self.get(name) File "/usr/lib/xen-3.2-1/lib/python/xen/web/SrvDir.py", line 82, in get val = val.getobj() File "/usr/lib/xen-3.2-1/lib/python/xen/web/SrvDir.py", line 52, in getobj File "/usr/lib/xen-3.2-1/lib/python/xen/xend/server/SrvNode.py", line 30, in _ _init__ self.xn = XendNode.instance() File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendNode.py", line 709, in instance inst = XendNode() File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendNode.py", line 164, in __init__ saved_pifs = self.state_store.load_state('pif') File "/usr/lib/xen-3.2-1/lib/python/xen/xend/XendStateStore.py", line 104, in load_state dom = minidom.parse(xml_path) File "/usr/lib/python2.5/xml/dom/minidom.py", line 1915, in parse return expatbuilder.parse(file) File "/usr/lib/python2.5/xml/dom/expatbuilder.py", line 924, in parse result = builder.parseFile(fp) File "/usr/lib/python2.5/xml/dom/expatbuilder.py", line 211, in parseFile parser.Parse("", True) ExpatError: no element found: line 1, column 0 [2010-04-18 13:01:34 4253] INFO (SrvDaemon:219) Xend exited with status 1. Any clues as to what might be going wrong?

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  • Is quoted-printable enough to make a mail compliant with the line-length-restriction posed in RFC 2822?

    - by Mnementh
    In RFC 2822 (defining E-Mail) is defined, that no line SHOULD be longer than 78 chars (excluding CRLF) and MUST not longer than 998 characters. With quoted-printable longer lines will be broken into more lines, ending each with a '=' until the real linebreak is reached. Conforms a mail to the standard, if it contains lines longer than 78 (or 998) characters but is encoded with quoted-printable? There are arguments, that this isn't compliant, because the receiving mail-client has longer lines after decoding the quoted-printable message.

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  • How do I make ncat not send a line-feed?

    - by tladuke
    I'm on Windows 7 Powershell and have ncat from http://nmap.org/ncat/ I'm trying to send "foo" to some network device PS> ncat -u 192.168.1.255 6061 foo but it sends "foo\n" (66 6f 6f 0a) and the line-feed makes the device not recognize the command. there's a -C option to add a carriage return, but that's no help. I made a text file containing "foo" and did PS> cat .\test.txt | ncat -u 192.168.1.255 6061 but that also adds CRLF

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  • Is there a good command-line OS from which I can launch VMs?

    - by Dredj
    Generally speaking, I'm interested in something that can load quickly and, depending on what I want to do, can choose to launch a Virtual Machine that is tailored to my desired activity. So, something that loads to (preferably) a command line, then if I want to run my Windows 7 machine that has all of my programming junk on it, I can simply enter the command to launch some VM player and close it when I'm done.

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  • How does NMap decide to print a progress line?

    - by Andrew Bolster
    Checking a larger subnet than I normally do; mapping out a cluster suite in a university for a traffic mapping project (permission attained), and I was wondering something. NMap usually prints its progress periodically, but I'm unclear to what that 'periodically' is, because the cirrent scan printed a line for basically every 100th of a percent up to 1% done, then one at 1.5%, and has said nothing since. I suspect that it changes at different 'levels' but does anyone have an actual answer?

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  • How to start "explorer" process using command line (Vista)?

    - by Amby
    Is there a way to start windows "explorer" process from command line? Because of some problem in my Vista OS, explorer process crashes frequently (i can not see TaskBar after that) but using the open windows i can access the cmd.exe ( ctrl+alt+delete does not work). If there could be a command to start "explorer" process again or to start the Task manager then that would help a lot. Thanks Edit: explorer command starts the explorer process, but alt+ctrl+del is still not working, any help?

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  • How to start "explorer" process using command line (Vista)?

    - by Amby
    Is there a way to start windows "explorer" process from command line? Because of some problem in my Vista OS, explorer process crashes frequently (i can not see TaskBar after that) but using the open windows i can access the cmd.exe ( ctrl+alt+delete does not work). If there could be a command to start "explorer" process again or to start the Task manager then that would help a lot. Thanks

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  • Screen Snip/Capture Utility callable from API or command line?

    - by Raymond
    I am looking for a screen capture tool that is controllable from the command line. Ideally I would pass the filename, and possibly some options (capture mouse pointer or not, etc..), then it would take control, allow the user to select a region of the screen, and then save it to the specified file and disappear. screensnip.exe /output c:\users\public\pictures\screenshot.png /hidecursor user draws rectangle on screen control passes back to batch file, script, etc....

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  • How to check if windows has automatic updates waiting from the command line?

    - by Lee
    If a Windows server (2k3/2k8) is set to "download but not install" updates, is there a way to check from the command line.. perhaps a log file or something I can check with powershell, to see if there are any updates actually waiting to be installed? I'm trying to prevent having to manually log on to each server to check, even though they want the "trigger" pulled manually. We have an automation system in place I can use (CA Autosys) - just not sure what to have it look for.

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  • Any script or command line tool that will allow me to sync a local folder with webdav?

    - by daniels
    I have a local folder on my mac that I want to sync with a webdav server. There are a lot of files in my folder and I would need that after I edit some files or add/remove folder to be able to sync the changes to the webdav server ignoring what it is on the server and always using my files. Is there any script or tool that I can use from command line to do that? And mounting the resource is not a solution.

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  • Update Windows Defender schedule via command line or gpo?

    - by Zenox
    I'm looking to find a way to update some Windows Defender settings via command line, gpo etc. From my research it looks like windows defender creates a hidden scheduled task named 'MP Scheduled Scan', but modifying this task does not seem to make a difference as to what shows up in the Windows Defender UI. I have also done some process monitoring to see what data Windows Defender uses and I can see that it reads/writes to the 'HKLM:\SOFTWARE\Microsoft\Windows Defender\Scan' ScheduleDay key, but if I attempt to modify this key, I get an "Error Writing the new values contents" error message.

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