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• boost::asio::async_write problem

  - by user368831

  Hi, I'm trying to figure out how asynchronous reads and writes work in boost asio by manipulating the echo example. Currently, I have a server that should, when sent a sentence, respond with only the first word. However, the boost::asio::async_write never seems to complete even though the write handler is being called. Can someone please explain what's going on? Here's the code: #include <cstdlib> #include <iostream> #include <boost/bind.hpp> #include <boost/asio.hpp> using boost::asio::ip::tcp; class session { public: session(boost::asio::io_service& io_service) : socket_(io_service) { } tcp::socket& socket() { return socket_; } void start() { std::cout<<"starting"<<std::endl; boost::asio::async_read_until(socket_, buffer, ' ', boost::bind(&session::handle_read, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } void handle_read(const boost::system::error_code& error, size_t bytes_transferred) { // std::ostringstream ss; // ss<<&buffer; char* c = new char[bytes_transferred]; //std::string s; buffer.sgetn(c,bytes_transferred); std::cout<<"data: "<< c<<" bytes: "<<bytes_transferred<<std::endl; if (!error) { boost::asio::async_write(socket_, boost::asio::buffer(c,bytes_transferred), boost::bind(&session::handle_write, this, boost::asio::placeholders::error)); } else { delete this; } } void handle_write(const boost::system::error_code& error) { std::cout<<"handling write"<<std::endl; if (!error) { } else { delete this; } } private: tcp::socket socket_; boost::asio::streambuf buffer; }; class server { public: server(boost::asio::io_service& io_service, short port) : io_service_(io_service), acceptor_(io_service, tcp::endpoint(tcp::v4(), port)) { session* new_session = new session(io_service_); acceptor_.async_accept(new_session->socket(), boost::bind(&server::handle_accept, this, new_session, boost::asio::placeholders::error)); } void handle_accept(session* new_session, const boost::system::error_code& error) { if (!error) { new_session->start(); new_session = new session(io_service_); acceptor_.async_accept(new_session->socket(), boost::bind(&server::handle_accept, this, new_session, boost::asio::placeholders::error)); } else { delete new_session; } } private: boost::asio::io_service& io_service_; tcp::acceptor acceptor_; }; int main(int argc, char* argv[]) { try { if (argc != 2) { std::cerr << "Usage: async_tcp_echo_server <port>\n"; return 1; } boost::asio::io_service io_service; using namespace std; // For atoi. server s(io_service, atoi(argv[1])); io_service.run(); } catch (std::exception& e) { std::cerr << "Exception: " << e.what() << "\n"; } return 0; } Thanks!

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• Filtering in a HierarchicalDataTemplate via MarkupExtension?

  - by Dan Bryant

  I'm trying to create a MarkupExtension to allow filtering of items in an ItemsSource of a HierarchicalDataTemplate. In particular, I'd like to be able to supply a method name that will be executed on the DataContext in order to perform the filtering. The usage syntax I'm after looks like this: <HierarchicalDataTemplate DataType="{x:Type src:DeviceBindingViewModel}" ItemsSource="{Utilities:FilterCollection {Binding Definition.Entries}, MethodName=FilterEntries}"> <StackPanel Orientation="Horizontal"> <Image Source="{StaticResource BindingImage}" Width="24" Height="24" Margin="3"/> <TextBlock Text="{Binding DisplayName}" FontSize="12" VerticalAlignment="Center"/> </StackPanel> </HierarchicalDataTemplate> My code for the custom MarkupExtension looks like this: public sealed class FilterCollectionExtension : MarkupExtension { private readonly MultiBinding _binding; private Predicate<Object> _filterMethod; public string MethodName { get; set; } public FilterCollectionExtension(Binding binding) { _binding = new MultiBinding(); _binding.Bindings.Add(binding); //We package a reference to the DataContext with the binding so that the Converter has access to it var selfBinding = new Binding {RelativeSource = RelativeSource.Self}; _binding.Bindings.Add(selfBinding); _binding.Converter = new InternalConverter(this); } public FilterCollectionExtension(Binding binding, string methodName) : this(binding) { MethodName = methodName; } public override object ProvideValue(IServiceProvider serviceProvider) { return _binding; } private bool FilterInternal(Object dataContext, Object value) { //Filtering is only applicable if a DataContext is defined if (dataContext != null) { if (_filterMethod == null) { var type = dataContext.GetType(); var method = type.GetMethod(MethodName, new[] { typeof(Object) }); if (method == null || method.ReturnType != typeof(bool)) throw new InvalidOperationException("Could not locate a filter predicate named " + MethodName + " on the DataContext"); _filterMethod = (Predicate<Object>)Delegate.CreateDelegate(typeof(Predicate<Object>), dataContext, method); } else { if (_filterMethod.Target != dataContext) { _filterMethod = (Predicate<Object>) Delegate.CreateDelegate(typeof (Predicate<Object>), dataContext, _filterMethod.Method); } } if (_filterMethod != null) return _filterMethod(value); } //If no filtering resolved, just allow all elements return true; } private class InternalConverter : IMultiValueConverter { private readonly FilterCollectionExtension _owner; public InternalConverter(FilterCollectionExtension owner) { _owner = owner; } public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture) { var enumerable = values[0]; var targetElement = (FrameworkElement)values[1]; var view = CollectionViewSource.GetDefaultView(enumerable); view.Filter = item => _owner.FilterInternal(targetElement.DataContext, item); return view; } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture) { throw new NotSupportedException("Cannot convert back"); } } } I can see that the extension is instantiated and I can see it return the MultiBinding that is used by the Template. I also see the call to the InternalConverter.Convert method, which sees the expected parameters (I see the collection provided by the nested {Binding}) and is successfully able to retrieve the ICollectionView for the incoming collection. The only problem is that FilterInternal never gets called. The template is ultimately being used by a TreeView, if that's relevant. I haven't been able to figure out why the FilterInternal method is not being called and I was hoping somebody might be able to offer some insight.

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• Need help diagnosing network performance issues

  - by tokes

  I am currently working in a developing country as a system analyst for a government department. My area of expertise is software projects, but I've come across a few issues with the network setup in my office. (Unfortunately, being a developing country, there's not a lot of professional help available for this sort of thing.) Most recently, I am trying to diagnose a problem with slowness on the network. Our office is connected to the internet via an ADSL wireless modem/router (called Router). The modem is connected via ethernet to a switch (called Switch). The modem also acts as a wireless access point (called Wireless1), though because it is in a room at the end of the floor, it's range is limited. There are ethernet ports installed around the office. The cables of these all lead back to the same switch. In closer vicinity to the bulk of the client computers, there is another wireless router that acts as an access point for those clients (called Wireless2). That router is connected via ethernet to a wall port, and therefore to Switch. There is also a Windows server which acts as a DNS server (called DNSBox) which is located in the same room and is connected directly to Switch. ---Internet----------| Router/Wireless1 192.168.10.1 ---------------| |----|=========| DNSBox | |-------------------- 192.168.10.4 --------------------| Switch |---Other clients---- | |-------------------- |----|=========| Wireless2 ------------------| 192.168.10.198 One final thing to mention about the network setup. All clients are configured with manual IP addresses. Their router/gateway is set to the IP address of Router, and their DNS server is set to the IP address of DNSBox (with a secondary IP set to an external IP - that of our ISP's DNS server). Here are the symptoms we are experiencing: Clients connected to Wireless2 AP experience slow and unstable connections to the internet. (Slow here is defined as speeds of ~1KB/s, though ping response times seem to be as normal.) Clients connected via ethernet to Switch also experience the same slowness. Clients connected to Wireless1 AP (i.e. connecting via wireless directly to the ADSL modem) experience normal connections to the internet. Clients connected via ethernet to Router (i.e. connecting via ethernet directly to the ADSL modem) also experience normal connections to the internet. I also tried to gauge the connection performance between two machines on the network via ethernet: A file transfer between two clients who were both directly connected to Switch was the fastest; A file transfer between one client directly connected to Switch, and one client directly connected to Router (which is directly connected to Switch) performed much slower; A file transfer between two clients directly connected to Router also performed slowly. Things I have attempted to diagnose the problem: Restarted Switch -- no change. We tried unplugging ethernet jacks from Switch 4 at a time and testing the internet connection. The thought here was that perhaps a client on the network has contracted a virus, and is possibly spamming the network with traffic? (Not very technical, I know.) Unfortunately we couldn't get any significant increases in performance using this method. There were a couple of times when it seemed to be better, but then the connection speed quickly dropped back to slow/dead pace. I didn't want to unplug all jacks from Switch because I was concerned that users might be affected or that I would re-plug in the jacks incorrectly (should I even be worried about that? a port is a port on a switch, right?) I tried swapping the ethernet cable used to connect Router to Switch -- no change in performance. I tried swapping the port used on Switch for Router -- no change in performance. Anyone got any ideas on what this could be? Should I be mentioning specific brand names/models of the hardware used? Virii outbreaks are common in this country/office -- what could I be doing to figure out if a virus is at fault? If it is a virus, it doesn't seem to be generating a lot of traffic to/from the internet, because a) I can still get a good speed if I am directly connected to Router / Wireless1 and b) our ISP data usage has not risen suspiciously. Thanks for your help! Update #1 Here are the specs of some of the hardware: Switch is an Edimax ES3132RL 32-Port 10/100 Rackmount Switch Router is a D-Link DSL-G604T Update #2 I just tried unplugging everything except a laptop and Router from Switch. Speeds are still slow. I guess that means that Router / Switch are not being flooded? It seems more and more likely that the cause is something to do with the interaction between Router and Switch. However, I still can't find any useful resources on setting the LAN speed for either (and I'm not well-versed in these advanced networking configurations).

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• If record exists in database, UPDATE a single column

  - by Doug

  I have a bulk uploading object in place that is being used to bulk upload roughly 25-40 image files at a time. Each image is about 100-150 kb in size. During the upload, I've created a for each loop that takes the file name of the image (minus the file extension) to write it into a column named "sku". Also, for each file being uploaded, the date is recorded to a column named DateUpdated, as well as some image path data. Here is my c# code: protected void graphicMultiFileButton_Click(object sender, EventArgs e) { //graphicMultiFile is the ID of the bulk uploading object ( provided by Dean Brettle: http://www.brettle.com/neatupload ) if (graphicMultiFile.Files.Length > 0) { foreach (UploadedFile file in graphicMultiFile.Files) { //strip ".jpg" from file name (will be assigned as SKU) string sku = file.FileName.Substring(0, file.FileName.Length - 4); //assign the directory where the images will be stored on the server string directoryPath = Server.MapPath("~/images/graphicsLib/" + file.FileName); //ensure that if image existes on server that it will get overwritten next time it's uploaded: file.MoveTo(directoryPath, MoveToOptions.Overwrite); //current sql that inserts a record to the db SqlCommand comm; SqlConnection conn; string connectionString = ConfigurationManager.ConnectionStrings["DataConnect"].ConnectionString; conn = new SqlConnection(connectionString); comm = new SqlCommand("INSERT INTO GraphicsLibrary (sku, imagePath, DateUpdated) VALUES (@sku, @imagePath, @DateUpdated)", conn); comm.Parameters.Add("@sku", System.Data.SqlDbType.VarChar, 50); comm.Parameters["@sku"].Value = sku; comm.Parameters.Add("@imagePath", System.Data.SqlDbType.VarChar, 300); comm.Parameters["@imagePath"].Value = "images/graphicsLib/" + file.FileName; comm.Parameters.Add("@DateUpdated", System.Data.SqlDbType.DateTime); comm.Parameters["@DateUpdated"].Value = DateTime.Now; conn.Open(); comm.ExecuteNonQuery(); conn.Close(); } } } After images are uploaded, managers will go back and re-upload images that have previously been uploaded. This is because these product images are always being revised and improved. For each new/improved image, the file name and extension will remain the same - so that when image 321-54321.jpg was first uploaded to the server, the new/improved version of that image will still have the image file name as 321-54321.jpg. I can't say for sure if the file sizes will remain in the 100-150KB range. I'll assume that the image file size will grow eventually. When images get uploaded (again), there of course will be an existing record in the database for that image. What is the best way to: Check the database for the existing record (stored procedure or SqlDataReader or create a DataSet ...?) Then if record exists, simply UPDATE that record so that the DateUpdated column gets today's date. If no record exists, do the INSERT of the record as normal. Things to consider: If the record exists, we'll let the actual image be uploaded. It will simply overwrite the existing image so that the new version gets displayed on the web. We're using SQL Server 2000 on hosted environment (DiscountAsp). I'm programming in C#. The uploading process will be used by about 2 managers a few times a month (each) - which to me is not a allot of usage. Although I'm a jr. developer, I'm guessing that a stored procedure would be the way to go. Just seems more efficient - to do this record check away from the for each loop... but not sure. I'd need extra help writing a sproc, since I don't have too much experience with them. Thank everyone...

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• Linker error when compiling boost.asio example

  - by Alon

  Hi, I'm trying to learn a little bit C++ and Boost.Asio. I'm trying to compile the following code example: #include <iostream> #include <boost/array.hpp> #include <boost/asio.hpp> using boost::asio::ip::tcp; int main(int argc, char* argv[]) { try { if (argc != 2) { std::cerr << "Usage: client <host>" << std::endl; return 1; } boost::asio::io_service io_service; tcp::resolver resolver(io_service); tcp::resolver::query query(argv[1], "daytime"); tcp::resolver::iterator endpoint_iterator = resolver.resolve(query); tcp::resolver::iterator end; tcp::socket socket(io_service); boost::system::error_code error = boost::asio::error::host_not_found; while (error && endpoint_iterator != end) { socket.close(); socket.connect(*endpoint_iterator++, error); } if (error) throw boost::system::system_error(error); for (;;) { boost::array<char, 128> buf; boost::system::error_code error; size_t len = socket.read_some(boost::asio::buffer(buf), error); if (error == boost::asio::error::eof) break; // Connection closed cleanly by peer. else if (error) throw boost::system::system_error(error); // Some other error. std::cout.write(buf.data(), len); } } catch (std::exception& e) { std::cerr << e.what() << std::endl; } return 0; } With the following command line: g++ -I /usr/local/boost_1_42_0 a.cpp and it throws an unclear error: /tmp/ccCv9ZJA.o: In function `__static_initialization_and_destruction_0(int, int)': a.cpp:(.text+0x654): undefined reference to `boost::system::get_system_category()' a.cpp:(.text+0x65e): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x668): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x672): undefined reference to `boost::system::get_generic_category()' a.cpp:(.text+0x67c): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::system::error_code::error_code()': a.cpp:(.text._ZN5boost6system10error_codeC2Ev[_ZN5boost6system10error_codeC5Ev]+0x10): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::asio::error::get_system_category()': a.cpp:(.text._ZN5boost4asio5error19get_system_categoryEv[boost::asio::error::get_system_category()]+0x7): undefined reference to `boost::system::get_system_category()' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_thread::~posix_thread()': a.cpp:(.text._ZN5boost4asio6detail12posix_threadD2Ev[_ZN5boost4asio6detail12posix_threadD5Ev]+0x1d): undefined reference to `pthread_detach' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_thread::join()': a.cpp:(.text._ZN5boost4asio6detail12posix_thread4joinEv[boost::asio::detail::posix_thread::join()]+0x25): undefined reference to `pthread_join' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_tss_ptr<boost::asio::detail::call_stack<boost::asio::detail::task_io_service<boost::asio::detail::epoll_reactor<false> > >::context>::~posix_tss_ptr()': a.cpp:(.text._ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEED2Ev[_ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEED5Ev]+0xf): undefined reference to `pthread_key_delete' /tmp/ccCv9ZJA.o: In function `boost::asio::detail::posix_tss_ptr<boost::asio::detail::call_stack<boost::asio::detail::task_io_service<boost::asio::detail::epoll_reactor<false> > >::context>::posix_tss_ptr()': a.cpp:(.text._ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEEC2Ev[_ZN5boost4asio6detail13posix_tss_ptrINS1_10call_stackINS1_15task_io_serviceINS1_13epoll_reactorILb0EEEEEE7contextEEC5Ev]+0x22): undefined reference to `pthread_key_create' collect2: ld returned 1 exit status How can I fix it? Thank you.

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• How to install PyQt on Mac OS X 10.6.

  - by Jebagnanadas

  Hello all, I'm quite new to Mac OS X. when i tried to install PyQt on Mac Os X after installing python 3.1, Qt 4.6.2 and SIP 4.10.1 i encounter the following error when i execute $python3 configure.py command. Determining the layout of your Qt installation... This is the GPL version of PyQt 4.7 (licensed under the GNU General Public License) for Python 3.1 on darwin. Type '2' to view the GPL v2 license. Type '3' to view the GPL v3 license. Type 'yes' to accept the terms of the license. Type 'no' to decline the terms of the license. Do you accept the terms of the license? yes Checking to see if the QtGui module should be built... Checking to see if the QtHelp module should be built... Checking to see if the QtMultimedia module should be built... Checking to see if the QtNetwork module should be built... Checking to see if the QtOpenGL module should be built... Checking to see if the QtScript module should be built... Checking to see if the QtScriptTools module should be built... Checking to see if the QtSql module should be built... Checking to see if the QtSvg module should be built... Checking to see if the QtTest module should be built... Checking to see if the QtWebKit module should be built... Checking to see if the QtXml module should be built... Checking to see if the QtXmlPatterns module should be built... Checking to see if the phonon module should be built... Checking to see if the QtAssistant module should be built... Checking to see if the QtDesigner module should be built... Qt v4.6.2 free edition is being used. Qt is built as a framework. SIP 4.10.1 is being used. The Qt header files are in /usr/include. The shared Qt libraries are in /Library/Frameworks. The Qt binaries are in /Developer/Tools/Qt. The Qt mkspecs directory is in /usr/local/Qt4.6. These PyQt modules will be built: QtCore. The PyQt Python package will be installed in /Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/site-packages. PyQt is being built with generated docstrings. PyQt is being built with 'protected' redefined as 'public'. The Designer plugin will be installed in /Developer/Applications/Qt/plugins/designer. The PyQt .sip files will be installed in /Library/Frameworks/Python.framework/Versions/3.1/share/sip/PyQt4. pyuic4, pyrcc4 and pylupdate4 will be installed in /Library/Frameworks/Python.framework/Versions/3.1/bin. Generating the C++ source for the QtCore module... sip: Usage: sip [-h] [-V] [-a file] [-b file] [-c dir] [-d file] [-e] [-g] [-I dir] [-j #] [-k] [-m file] [-o] [-p module] [-r] [-s suffix] [-t tag] [-w] [-x feature] [-z file] [file] Error: Unable to create the C++ code. Anybody here installed PyQt on Mac OS X 10.6.2 successfully.. Any help would be much appreciated.. Thanks in advance..

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• .Net Custom Configuration Section and Saving Changes within PropertyGrid

  - by Paul

  If I load the My.Settings object (app.config) into a PropertyGrid, I am able to edit the property inside the propertygrid and the change is automatically saved. PropertyGrid1.SelectedObject = My.Settings I want to do the same with a Custom Configuration Section. Following this code example (from here http://www.codeproject.com/KB/vb/SerializePropertyGrid.aspx), he is doing explicit serialization to disk when a "Save" button is pushed. Public Class Form1 'Load AppSettings Dim _appSettings As New AppSettings() Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click _appSettings = AppSettings.Load() ' Actually change the form size Me.Size = _appSettings.WindowSize PropertyGrid1.SelectedObject = _appSettings End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click _appSettings.Save() End Sub End Class In my code, my custom section Inherits from ConfigurationSection (see below) Question: Is there something built into ConfigurationSection class that does the autosave? If not, what is the best way to handle this, should it be in the PropertyGrid.PropertyValueChagned? (how does the My.Settings handle this internally?) Here is the example Custom Class that I am trying to get to auto-save and how I load into property grid. Dim config As System.Configuration.Configuration = _ ConfigurationManager.OpenExeConfiguration( _ ConfigurationUserLevel.None) PropertyGrid2.SelectedObject = config.GetSection("CustomSection") Public NotInheritable Class CustomSection Inherits ConfigurationSection ' The collection (property bag) that contains ' the section properties. Private Shared _Properties As ConfigurationPropertyCollection ' The FileName property. Private Shared _FileName As New ConfigurationProperty("fileName", GetType(String), "def.txt", ConfigurationPropertyOptions.IsRequired) ' The MasUsers property. Private Shared _MaxUsers _ As New ConfigurationProperty("maxUsers", _ GetType(Int32), 1000, _ ConfigurationPropertyOptions.None) ' The MaxIdleTime property. Private Shared _MaxIdleTime _ As New ConfigurationProperty("maxIdleTime", _ GetType(TimeSpan), TimeSpan.FromMinutes(5), _ ConfigurationPropertyOptions.IsRequired) ' CustomSection constructor. Public Sub New() _Properties = New ConfigurationPropertyCollection() _Properties.Add(_FileName) _Properties.Add(_MaxUsers) _Properties.Add(_MaxIdleTime) End Sub 'New ' This is a key customization. ' It returns the initialized property bag. Protected Overrides ReadOnly Property Properties() _ As ConfigurationPropertyCollection Get Return _Properties End Get End Property <StringValidator( _ InvalidCharacters:=" ~!@#$%^&*()[]{}/;'""|\", _ MinLength:=1, MaxLength:=60)> _ <EditorAttribute(GetType(System.Windows.Forms.Design.FileNameEditor), GetType(System.Drawing.Design.UITypeEditor))> _ Public Property FileName() As String Get Return CStr(Me("fileName")) End Get Set(ByVal value As String) Me("fileName") = value End Set End Property <LongValidator(MinValue:=1, _ MaxValue:=1000000, ExcludeRange:=False)> _ Public Property MaxUsers() As Int32 Get Return Fix(Me("maxUsers")) End Get Set(ByVal value As Int32) Me("maxUsers") = value End Set End Property <TimeSpanValidator(MinValueString:="0:0:30", _ MaxValueString:="5:00:0", ExcludeRange:=False)> _ Public Property MaxIdleTime() As TimeSpan Get Return CType(Me("maxIdleTime"), TimeSpan) End Get Set(ByVal value As TimeSpan) Me("maxIdleTime") = value End Set End Property End Class 'CustomSection

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• Linux IPTables / routing issue

  - by Jon

  Hi all, EDIT 1/3/10 22:00 GMT - rewrote some of it after further investigation It has been a while since I looked at IPtables and I seem to be worse than before as I can not seem to get my webserver online. Below is my firewall rules on the gateway server that is running the dhcp server accessing the net. The webserver is inside my network on a static IP (192.168.0.98, default port). When I use Nmap or GRC.com I see that port 80 is open on the gateway server but when I browse to it, (via public URL. http://www.houseofhawkins.com) it always fails with a connection error, (nmap cannot connect and figure out what the web server is either). I can nmap the webserver and browse to it just fine via same IP inside my network. I believe it is my IPTable rules that are not letting it through. Internally I can route all my requests. Each machine can browse to the website and traffic works just fine. I can MSTSC / ssh to all the webservers internally and they inturn can connect to the web. IPTABLE: *EDIT - Added new firewall rules 2/3/10 * #!/bin/sh iptables="/sbin/iptables" modprobe="/sbin/modprobe" depmod="/sbin/depmod" EXTIF="eth2" INTIF="eth1" load () { $depmod -a $modprobe ip_tables $modprobe ip_conntrack $modprobe ip_conntrack_ftp $modprobe ip_conntrack_irc $modprobe iptable_nat $modprobe ip_nat_ftp echo "enable forwarding.." echo "1" > /proc/sys/net/ipv4/ip_forward echo "enable dynamic addr" echo "1" > /proc/sys/net/ipv4/ip_dynaddr # start firewall # default policies $iptables -P INPUT DROP $iptables -F INPUT $iptables -P OUTPUT DROP $iptables -F OUTPUT $iptables -P FORWARD DROP $iptables -F FORWARD $iptables -t nat -F #echo " Opening loopback interface for socket based services." $iptables -A INPUT -i lo -j ACCEPT $iptables -A OUTPUT -o lo -j ACCEPT #echo " Allow all connections OUT and only existing and related ones IN" $iptables -A INPUT -i $INTIF -j ACCEPT $iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A OUTPUT -o $EXTIF -j ACCEPT $iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A FORWARD -i $EXTIF -o $INTIF -m state --state ESTABLISHED,RELATED -j ACCEPT $iptables -A FORWARD -i $INTIF -o $EXTIF -j ACCEPT $iptables -A FORWARD -j LOG --log-level 7 --log-prefix "Dropped by firewall: " $iptables -A INPUT -j LOG --log-level 7 --log-prefix "Dropped by firewall: " $iptables -A OUTPUT -j LOG --log-level 7 --log-prefix "Dropped by firewall: " #echo " Enabling SNAT (MASQUERADE) functionality on $EXTIF" $iptables -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE $iptables -A INPUT -i $INTIF -j ACCEPT $iptables -A OUTPUT -o $INTIF -j ACCEPT #echo " Allowing packets with ICMP data (i.e. ping)." $iptables -A INPUT -p icmp -j ACCEPT $iptables -A OUTPUT -p icmp -j ACCEPT $iptables -A INPUT -p udp -i $INTIF --dport 67 -m state --state NEW -j ACCEPT #echo " Port 137 is for NetBIOS." $iptables -A INPUT -i $INTIF -p udp --dport 137 -j ACCEPT $iptables -A OUTPUT -o $INTIF -p udp --dport 137 -j ACCEPT #echo " Opening port 53 for DNS queries." $iptables -A INPUT -p udp -i $EXTIF --sport 53 -j ACCEPT #echo " opening Apache webserver" $iptables -A PREROUTING -t nat -i $EXTIF -p tcp --dport 80 -j DNAT --to 192.168.0.96:80 $iptables -A FORWARD -p tcp -m state --state NEW -d 192.168.0.96 --dport 80 -j ACCEPT } flush () { echo "flushing rules..." $iptables -P FORWARD ACCEPT $iptables -F INPUT $iptables -P INPUT ACCEPT echo "rules flushed" } case "$1" in start|restart) flush load ;; stop) flush ;; *) echo "usage: start|stop|restart." ;; esac exit 0 route info: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 5e0412a6.bb.sky * 255.255.255.255 UH 0 0 0 eth2 192.168.0.0 * 255.255.255.0 U 0 0 0 eth1 default 5e0412a6.bb.sky 0.0.0.0 UG 100 0 0 eth2 ifconfig: eth1 Link encap:Ethernet HWaddr 00:22:b0:cf:4a:1c inet addr:192.168.0.1 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::222:b0ff:fecf:4a1c/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:79023 errors:0 dropped:0 overruns:0 frame:0 TX packets:57786 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:11580918 (11.5 MB) TX bytes:22872030 (22.8 MB) Interrupt:17 Base address:0x2b00 eth2 Link encap:Ethernet HWaddr 00:0c:f1:7c:45:5b inet addr:94.4.18.166 Bcast:94.4.18.166 Mask:255.255.255.255 inet6 addr: fe80::20c:f1ff:fe7c:455b/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:57038 errors:0 dropped:0 overruns:0 frame:0 TX packets:34532 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:21631721 (21.6 MB) TX bytes:7685444 (7.6 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:16 errors:0 dropped:0 overruns:0 frame:0 TX packets:16 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:1517 (1.5 KB) TX bytes:1517 (1.5 KB) EDIT OK so as requested I will try and expand on my infrastructure: I previously had it setup with a Sky broadband modem router that did the DHCP and I used its web interface to port forward the web across to the web server. The network looked something like this: I have now replaced the sky modem with a dlink modem which gives the IP to the gateway server that now does the DHCP. It looks like: The internet connection is a standard broadband connection with a dynamic IP, (use zoneedit.com to keep it updated). I have tried it on each of the webservers(one Ubuntu Apache server and one WS2008 IIS7). I think there must also be an issue with my IPTable rules as it can route to my win7 box which has the default IIS7 page and that would not display when I forwarded all port 80 to it. I would be really grateful for any and all help with this. Thanks Jon

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• Understanding Node.js and concept of non-blocking I/O

  - by Saif Bechan

  Recently I became interested in using Node.js to tackle some of the parts of my web-application. I love the part that its full JavaScript and its very light weight so no use anymore to call an JavaScript-PHP call but a lighter JavaScript-JavaScript call. I however do not understand all the concepts explained. Basic concepts Now in the presentation for Node.js Ryan Dahl talks about non-blocking IO and why this is the way we need to create our programs. I can understand the theoretical concept. You just don't wait for a response, you go ahead and do other things. You make a callback for the response, and when the response arrives millions of clock-cycles later, you can fire that. If you have not already I recommend to watch this presentation. It is very easy to follow and pretty detailed. There are some nice concepts explained on how to write your code in a good manner. There are also some examples given and I am going to work with the basic example given. Examples The way we do thing now: puts("Enter your name: "); var name = gets(); puts("Name: " + name); Now the problem with this is that the code is halted at line 1. It blocks your code. The way we need to do things according to node puts("Enter your name: "); gets(function (name) { puts("Name: " + name); }); Now with this your program does not halt, because the input is a function within the output. So the programs continues to work without halting. Questions Now the basic question I have is how does this work in real-life situations. I am talking here for the use in web-applications. The application I am writing does I/O, bit is still does it in am blocking matter. I think that most of the time, if not all, you need to block, because you have to wait on what the response is you have to work with. When you need to get some information from the database, most of the time this data needs to be verified before you can further with the code. Example 1 If you take a login for example. You have to wait for the database to response to return, because you can not do anything else. I can't see a way around this without blocking. Example 2 Going back to the basic example. The use just request something from a database which does not need any verification. You still have to block because you don't have anything to do more. I can not come up with a single example where you want to do other things while you wait for the response to return. Possible answers I have read that this frees up recourses. When you program like this it takes less CPU or memory usage. So this non-blocking IO is ONLY meant to free up recourses and does not have any other practical use. Not that this is not a huge plus, freeing up recourses is always good. Yet I fail to see this as a good solution. because in both of the above examples, the program has to wait for the response of the user. Whether this is inside a function, or just inline, in my opinion there is a program that wait for input. Resources I looked at I have looked at some recourses before I posted this question. They talk a lot about the theoretical concept, which is quite clear. Yet i fail to see some real-life examples where this is makes a huge difference. Stackoverflow: What is in simple words blocking IO and non-blocking IO? Blocking IO vs non-blocking IO; looking for good articles tidy code for asynchronous IO Other recources: Wikipedia: Asynchronous I/O Introduction to non-blocking I/O The C10K problem

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• Reliable way of generating unique hardware ID

  - by mr.b

  Question: what's the best way to accomplish following. I have to come up with unique ID for each networked client, such that: it (ID) should persist once client software is installed on target computer, and should continue to persist if software is re-installed on same computer and same OS installment, it should not change if hardware configuration is modified in most ways (except changing the motherboard) When hard drive with client software installed is cloned to another computer with identical hardware configuration (or, as similar as possible), client software should be aware of that change. A little bit of explanation and some back-story: This question is basically age old question that also touches topic of software copy-protection, as some of mechanisms used in that area are mentioned here. I should be clear at this point that I'm not looking for a copy-protection scheme. Please, read on. :) I'm working on a client-server software that is supposed to work in local network. One of problems I have to solve is to identify each unique client in network (not so much of a problem), so that I can apply certain attributes to every specific client, retain and enforce those attributes during deployment lifetime of a specific client. While I was looking for a solution, I was aware of following: Windows activation system uses some kind of heavy fingerprinting mechanism, that is extremely sensitive to hardware modifications, Disk imaging software copies along all Volume IDs (tied to each partition when formatted), and custom, uniquely generated IDs during installation process, during first run, or in any other way, that is strictly software in its nature, and stored in registry or on hard drive, so it's very easy to confuse two Obvious choice for this kind of problem would be to find out BIOS identifiers (not 100% sure if this is unique through identical motherboard models, though), as that's the only thing I can rely on, that isn't duplicated, transferred by cloning, and that can't be changed (at least not by using some user-space program). Everything else fails as either being not reliable (MAC cloning, anyone?), or too demanding (in terms that it's too sensitive to configuration changes). Am I missing something obvious here? Sub-question that I'd like to ask is, am I doing it correctly, architecture-wise? Perhaps there is a better tool for task that I have to accomplish... Another approach I had in mind is something similar to handshake mechanism, where server maintains internal lookup table of connected client IDs (which can be even completely software-based and non-unique at any given moment), and tells client to come up with different ID during handshake, if duplicate ID is provided upon connection. That approach, unfortunately, doesn't play nicely with one of requirements to tie attributes to specific client during lifetime.

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• ASP.NET WebControl ITemplate child controls are null

  - by tster

  Here is what I want: I want a control to put on a page, which other developers can place form elements inside of to display the entities that my control is searching. I have the Searching logic all working. The control builds custom search fields and performs searches based on declarative C# classes implementing my SearchSpec interface. Here is what I've been trying: I've tried using ITemplate on a WebControl which implements INamingContainer I've tried implementing a CompositeControl The closest I can get to working is below. OK I have a custom WebControl [ AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal), AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal), DefaultProperty("SearchSpecName"), ParseChildren(true), ToolboxData("<{0}:SearchPage runat=\"server\"> </{0}:SearchPage>") ] public class SearchPage : WebControl, INamingContainer { [Browsable(false), PersistenceMode(PersistenceMode.InnerProperty), DefaultValue(typeof(ITemplate), ""), Description("Form template"), TemplateInstance(TemplateInstance.Single), TemplateContainer(typeof(FormContainer))] public ITemplate FormTemplate { get; set; } public class FormContainer : Control, INamingContainer{ } public Control MyTemplateContainer { get; private set; } [Bindable(true), Category("Behavior"), DefaultValue(""), Description("The class name of the SearchSpec to use."), Localizable(false)] public virtual string SearchSpecName { get; set; } [Bindable(true), Category("Behavior"), DefaultValue(true), Description("True if this is query mode."), Localizable(false)] public virtual bool QueryMode { get; set; } private SearchSpec _spec; private SearchSpec Spec { get { if (_spec == null) { Type type = Assembly.GetExecutingAssembly().GetTypes().Where(t => t.Name == SearchSpecName).First(); _spec = (SearchSpec)Assembly.GetExecutingAssembly().CreateInstance(type.Namespace + "." + type.Name); } return _spec; } } protected override void CreateChildControls() { if (FormTemplate != null) { MyTemplateContainer = new FormTemplateContainer(this); FormTemplate.InstantiateIn(MyTemplateContainer); Controls.Add(MyTemplateContainer); } else { Controls.Add(new LiteralControl("blah")); } } protected override void RenderContents(HtmlTextWriter writer) { // <snip> } protected override HtmlTextWriterTag TagKey { get { return HtmlTextWriterTag.Div; } } } public class FormTemplateContainer : Control, INamingContainer { private SearchPage parent; public FormTemplateContainer(SearchPage parent) { this.parent = parent; } } then the usage: <tster:SearchPage ID="sp1" runat="server" SearchSpecName="TestSearchSpec" QueryMode="False"> <FormTemplate> <br /> Test Name: <asp:TextBox ID="testNameBox" runat="server" Width="432px"></asp:TextBox> <br /> Owner: <asp:TextBox ID="ownerBox" runat="server" Width="427px"></asp:TextBox> <br /> Description: <asp:TextBox ID="descriptionBox" runat="server" Height="123px" Width="432px" TextMode="MultiLine" Wrap="true"></asp:TextBox> </FormTemplate> </tster:SearchPage> The problem is that in the CodeBehind, the page has members descriptionBox, ownerBox and testNameBox. However, they are all null. Furthermore, FindControl("ownerBox") returns null as does this.sp1.FindControl("ownerBox"). I have to do this.sp1.MyTemplateContainer.FindControl("ownerBox") to get the control. How can I make it so that the C# Code Behind will have the controls generated and not null in my Page_Load event so that developers can just do this: testNameBox.Text = "foo"; ownerBox.Text = "bar"; descriptionBox.Text = "baz";

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• All downloads being interrupted

  - by Jake

  System: Windows 7 Professional 64bit. 8GB RAM, Intel i5-2400 CPU, +300GB free on the hard drive. AVG Internet Security 2012 (enabled & disabled, with firewall enabled and disabled - no effect for either). This computer is less than a year old. Network: This problem is occurring on a single computer on a network with multiple computers. The router is a Motorola Netopia 3347-02 (DSL Modem/Wireless Router combined). The computer is plugged in directly to the modem, other computers are using the wireless successfully. The router has been reset. The only thing odd about the connection between the router and computer is that it is configured to allow RDP through, so it is assigned a static IP by the router and port forwarding is enabled for port 3389. Also, though I doubt it matters, a second wireless router is active behind this router providing a second network that some computers in the area use without issues. Details: All downloads initiated on this specific computer eventually fail, this includes streaming from youtube, specialized downloads (itunes), downloads from websites, FTP downloads, etc. Failure occurs with all browsers, but in chrome this is the process it takes: 1) Download begins normally, 2) At some point between (observed) 7MBs and 229MBs the download stops progressing (at this point, if watching chrome's task manager, you can see the network activity for the downloading tab drop to 0kps), 3) for some time the download sits there still attempting to complete, but will eventually display "123,049,871/0 B, Interrupted" (where the number is whatever it actually got to). The file I am using to test this is a very large .zip file located on a server I control, but the problem seems to occur on any site. The amount downloaded is completely random, and seems to be more time-based than anything (if I start a download immediately after the last one fails, it tends to get further than the last one). Small files can get through for this reason, though they can fail as well. In a test where I simultaneously downloaded the same file via HTTP (chrome) and FTP (windows explorer), both downloads failed at the same instant, though explorer displayed "Connection timed out" several minutes before chrome finally showed the download as interrupted. Other things I have tried based on advice given to people with similar/identical problems: Setting my MTU to 1492 (as described here: http://blog.thecompwiz.com/2011/08/networking-issues.html) Disabling write caching to the hard drive storing the download on an external device successfully transmitted +1GB file from one computer on the same network to this computer disabling indexing in the folder the download was being stored in disabling all security software checked to make sure all drivers were up to date read about 50 accounts with nearly exact descriptions of what I'm experiencing, none of which had a solution given Running Processes: Image Name PID Session Name Session# Mem Usage ========================= ======== ================ =========== ============ System Idle Process 0 Services 0 24 K System 4 Services 0 104,836 K smss.exe 332 Services 0 1,276 K csrss.exe 764 Services 0 5,060 K wininit.exe 820 Services 0 4,748 K csrss.exe 844 Console 1 23,764 K services.exe 876 Services 0 11,856 K lsass.exe 892 Services 0 14,420 K lsm.exe 900 Services 0 7,820 K winlogon.exe 944 Console 1 7,716 K svchost.exe 428 Services 0 12,744 K svchost.exe 796 Services 0 12,240 K svchost.exe 1036 Services 0 22,372 K svchost.exe 1084 Services 0 174,132 K svchost.exe 1112 Services 0 56,144 K svchost.exe 1288 Services 0 18,640 K svchost.exe 1404 Services 0 29,616 K spoolsv.exe 1576 Services 0 25,924 K svchost.exe 1616 Services 0 12,788 K AppleMobileDeviceService. 1728 Services 0 9,796 K avgwdsvc.exe 1820 Services 0 8,268 K mDNSResponder.exe 1844 Services 0 5,832 K w3dbsmgr.exe 1108 Services 0 43,760 K QBCFMonitorService.exe 1336 Services 0 16,408 K svchost.exe 2404 Services 0 28,240 K taskhost.exe 3020 Console 1 12,372 K dwm.exe 2280 Console 1 5,968 K explorer.exe 2964 Console 1 152,476 K WUDFHost.exe 3316 Services 0 6,740 K svchost.exe 3408 Services 0 5,556 K RAVCpl64.exe 3684 Console 1 13,864 K igfxtray.exe 3700 Console 1 7,804 K hkcmd.exe 3772 Console 1 7,868 K igfxpers.exe 3788 Console 1 10,940 K sidebar.exe 3836 Console 1 84,400 K chrome.exe 3964 Console 1 19,640 K pptd40nt.exe 4068 Console 1 5,156 K acrotray.exe 3908 Console 1 14,676 K avgtray.exe 3872 Console 1 9,508 K jusched.exe 4076 Console 1 4,412 K iTunesHelper.exe 1532 Console 1 87,308 K SearchIndexer.exe 3492 Services 0 36,948 K iPodService.exe 4136 Services 0 7,944 K BrccMCtl.exe 4276 Console 1 18,132 K splwow64.exe 4380 Console 1 32,600 K qbupdate.exe 4836 Console 1 24,236 K svchost.exe 4288 Services 0 20,700 K wmpnetwk.exe 3112 Services 0 9,516 K FNPLicensingService.exe 5248 Services 0 5,852 K QBW32.EXE 5508 Console 1 127,068 K QBDBMgrN.exe 5600 Services 0 42,252 K EXCEL.EXE 2512 Console 1 99,100 K LMS.exe 3188 Services 0 5,616 K UNS.exe 1600 Services 0 7,308 K axlbridge.exe 5260 Console 1 5,132 K chrome.exe 5888 Console 1 200,336 K chrome.exe 3536 Console 1 26,076 K chrome.exe 1952 Console 1 20,168 K chrome.exe 4596 Console 1 24,696 K chrome.exe 4292 Console 1 48,096 K chrome.exe 2796 Console 1 23,520 K Acrobat.exe 1240 Console 1 87,252 K 123w.exe 4892 Console 1 22,728 K calc.exe 1700 Console 1 12,636 K chrome.exe 1328 Console 1 28,888 K chrome.exe 3696 Console 1 47,012 K rundll32.exe 6320 Console 1 7,104 K chrome.exe 4928 Console 1 44,248 K AVGIDSAgent.exe 260 Services 0 12,940 K avgfws.exe 6052 Services 0 26,912 K avgnsa.exe 5064 Services 0 2,496 K avgrsa.exe 3088 Services 0 2,200 K avgcsrva.exe 2596 Services 0 380 K avgcsrva.exe 6948 Services 0 408 K StikyNot.exe 452 Console 1 14,772 K chrome.exe 4580 Console 1 28,200 K chrome.exe 4016 Console 1 57,756 K svchost.exe 7140 Services 0 4,500 K chrome.exe 6264 Console 1 56,824 K chrome.exe 7008 Console 1 56,896 K chrome.exe 2224 Console 1 38,032 K taskhost.exe 612 Console 1 7,228 K chrome.exe 6000 Console 1 10,928 K chrome.exe 2568 Console 1 43,052 K chrome.exe 272 Console 1 75,988 K chrome.exe 7328 Console 1 53,240 K PaprPort.exe 7976 Console 1 137,152 K pplinks.exe 7500 Console 1 14,052 K ppscanmg.exe 5744 Console 1 18,996 K taskeng.exe 7388 Console 1 6,308 K SearchProtocolHost.exe 8024 Services 0 8,804 K SearchFilterHost.exe 7232 Services 0 7,848 K chrome.exe 8016 Console 1 37,440 K cmd.exe 7692 Console 1 3,096 K conhost.exe 7516 Console 1 5,872 K tasklist.exe 8160 Console 1 5,772 K WmiPrvSE.exe 7684 Services 0 6,400 K Any help with this would be greatly appreciated, I've been beating my head against a wall over this all day. This computer serves dual purpose as the main company document server and the Owner's work computer, it's fairly important it be fully functional and I cannot figure this out.

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• Python: How to read huge text file into memory

  - by asmaier

  I'm using Python 2.6 on a Mac Mini with 1GB RAM. I want to read in a huge text file $ ls -l links.csv; file links.csv; tail links.csv -rw-r--r-- 1 user user 469904280 30 Nov 22:42 links.csv links.csv: ASCII text, with CRLF line terminators 4757187,59883 4757187,99822 4757187,66546 4757187,638452 4757187,4627959 4757187,312826 4757187,6143 4757187,6141 4757187,3081726 4757187,58197 So each line in the file consists of a tuple of two comma separated integer values. I want to read in the whole file and sort it according to the second column. I know, that I could do the sorting without reading the whole file into memory. But I thought for a file of 500MB I should still be able to do it in memory since I have 1GB available. However when I try to read in the file, Python seems to allocate a lot more memory than is needed by the file on disk. So even with 1GB of RAM I'm not able to read in the 500MB file into memory. My Python code for reading the file and printing some information about the memory consumption is: #!/usr/bin/python # -*- coding: utf-8 -*- import sys infile=open("links.csv", "r") edges=[] count=0 #count the total number of lines in the file for line in infile: count=count+1 total=count print "Total number of lines: ",total infile.seek(0) count=0 for line in infile: edge=tuple(map(int,line.strip().split(","))) edges.append(edge) count=count+1 # for every million lines print memory consumption if count%1000000==0: print "Position: ", edge print "Read ",float(count)/float(total)*100,"%." mem=sys.getsizeof(edges) for edge in edges: mem=mem+sys.getsizeof(edge) for node in edge: mem=mem+sys.getsizeof(node) print "Memory (Bytes): ", mem The output I got was: Total number of lines: 30609720 Position: (9745, 2994) Read 3.26693612356 %. Memory (Bytes): 64348736 Position: (38857, 103574) Read 6.53387224712 %. Memory (Bytes): 128816320 Position: (83609, 63498) Read 9.80080837067 %. Memory (Bytes): 192553000 Position: (139692, 1078610) Read 13.0677444942 %. Memory (Bytes): 257873392 Position: (205067, 153705) Read 16.3346806178 %. Memory (Bytes): 320107588 Position: (283371, 253064) Read 19.6016167413 %. Memory (Bytes): 385448716 Position: (354601, 377328) Read 22.8685528649 %. Memory (Bytes): 448629828 Position: (441109, 3024112) Read 26.1354889885 %. Memory (Bytes): 512208580 Already after reading only 25% of the 500MB file, Python consumes 500MB. So it seem that storing the content of the file as a list of tuples of ints is not very memory efficient. Is there a better way to do it, so that I can read in my 500MB file into my 1GB of memory?

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• Nginx + php-fpm "504 Gateway Time-out" error with almost zero load (on a test-server)

  - by rahul286

  After debugging for 6-hours - I am giving this up :| We have a nginx+php-fpm+mysql in LAN with almost 100 wordpress (created and used by different designers/developers all working on test wordpres setup) We are using nginx without any issues from long. Today, all of a sudden - nginx started returning "504 Gateway Time-out" out of the blue... I checked nginx error log for a virtual host... 2010/09/06 21:24:24 [error] 12909#0: *349 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *349 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:11 [error] 12909#0: *443 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 21:25:12 [error] 12909#0: *443 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:08:32 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:33 [error] 12909#0: *1025 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /info.php HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:09:40 [error] 12909#0: *1064 connect() failed (111: Connection refused) while connecting to upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:44 [error] 12909#0: *1313 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET / HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" 2010/09/06 22:24:53 [error] 12909#0: *1313 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 192.168.0.1, server: rahul286.rtcamp.info, request: "GET /favicon.ico HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "rahul286.rtcamp.info" As I run php-fpm on port 9000 via TCP mode, I ran "netstat | grep 9000" and noticed something unusual... (Pasting partial output here for ease of read) tcp 9 0 localhost:9000 localhost:36094 CLOSE_WAIT 14269/php5-fpm tcp 0 0 localhost:46664 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36135 CLOSE_WAIT - tcp 1257 0 localhost:9000 localhost:36125 CLOSE_WAIT - tcp 9 0 localhost:9000 localhost:36102 CLOSE_WAIT 14268/php5-fpm tcp 0 0 localhost:46662 localhost:9000 FIN_WAIT2 - tcp 745 0 localhost:9000 localhost:46644 CLOSE_WAIT - tcp 0 0 localhost:46658 localhost:9000 FIN_WAIT2 - tcp 1265 0 localhost:9000 localhost:46607 CLOSE_WAIT - tcp 0 0 localhost:46672 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1257 0 localhost:9000 localhost:36119 CLOSE_WAIT - tcp 1265 0 localhost:9000 localhost:46613 CLOSE_WAIT - tcp 0 0 localhost:46646 localhost:9000 FIN_WAIT2 - tcp 1257 0 localhost:9000 localhost:36137 CLOSE_WAIT - tcp 0 0 localhost:46670 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1265 0 localhost:9000 localhost:46619 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46668 ESTABLISHED - tcp 0 0 localhost:46648 localhost:9000 FIN_WAIT2 - tcp 1336 0 localhost:9000 localhost:46670 ESTABLISHED - tcp 9 0 localhost:9000 localhost:36108 CLOSE_WAIT 14274/php5-fpm tcp 1336 0 localhost:9000 localhost:46684 ESTABLISHED - tcp 0 0 localhost:46674 localhost:9000 ESTABLISHED 12909/nginx: worker tcp 1336 0 localhost:9000 localhost:46666 ESTABLISHED - tcp 1257 0 localhost:9000 localhost:46648 CLOSE_WAIT - tcp 1336 0 localhost:9000 localhost:46678 ESTABLISHED - tcp 0 0 localhost:46668 localhost:9000 ESTABLISHED 12909/nginx: wo There are plenty of "CLOSE_WAIT" & "FIN_WAIT2" pairs as highlighted below (in above output): tcp 1337 0 localhost:9000 localhost:46680 CLOSE_WAIT - tcp 0 0 localhost:46680 localhost:9000 FIN_WAIT2 - Please note port 46680 in above. I enabled mysql slow queries error log, but it didn't work. As of now restarting php5-fpm every minute via a cronjob (see command below) keeping everything running "smoothly" but I hate patchwork and want to solve this... 1 * * * * service php5-fpm restart > /dev/null I searched extensively on Google - got no help. As mentioned, this a test-server in LAN, CPU load is never crossed 0.10 and memory usage is also below 25% (System has 2GB RAM and ubuntu-server installed) So if you find its time-confusing to help me out, please atleast drop a hint. Thanks in advance for help. -Rahul (note - this is reposting of - http://forum.nginx.org/read.php?11,127694) Update: I found answer, which is posted below.

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• Load-balancing between a Procurve switch and a server

  - by vlad

  Hello I've been searching around the web for this problem i've been having. It's similar in a way to this question: How exactly & specifically does layer 3 LACP destination address hashing work? My setup is as follows: I have a central switch, a Procurve 2510G-24, image version Y.11.16. It's the center of a star topology, there are four switches connected to it via a single gigabit link. Those switches service the users. On the central switch, I have a server with two gigabit interfaces that I want to bond together in order to achieve higher throughput, and two other servers that have single gigabit connections to the switch. The topology looks as follows: sw1 sw2 sw3 sw4 | | | | --------------------- | sw0 | --------------------- || | | srv1 srv2 srv3 The servers were running FreeBSD 8.1. On srv1 I set up a lagg interface using the lacp protocol, and on the switch I set up a trunk for the two ports using lacp as well. The switch showed that the server was a lacp partner, I could ping the server from another computer, and the server could ping other computers. If I unplugged one of the cables, the connection would keep working, so everything looked fine. Until I tested throughput. There was only one link used between srv1 and sw0. All testing was conducted with iperf, and load distribution was checked with systat -ifstat. I was looking to test the load balancing for both receive and send operations, as I want this server to be a file server. There were therefore two scenarios: iperf -s on srv1 and iperf -c on the other servers iperf -s on the other servers and iperf -c on srv1 connected to all the other servers. Every time only one link was used. If one cable was unplugged, the connections would keep going. However, once the cable was plugged back in, the load was not distributed. Each and every server is able to fill the gigabit link. In one-to-one test scenarios, iperf was reporting around 940Mbps. The CPU usage was around 20%, which means that the servers could withstand a doubling of the throughput. srv1 is a dell poweredge sc1425 with onboard intel 82541GI nics (em driver on freebsd). After troubleshooting a previous problem with vlan tagging on top of a lagg interface, it turned out that the em could not support this. So I figured that maybe something else is wrong with the em drivers and / or lagg stack, so I started up backtrack 4r2 on this same server. So srv1 now uses linux kernel 2.6.35.8. I set up a bonding interface bond0. The kernel module was loaded with option mode=4 in order to get lacp. The switch was happy with the link, I could ping to and from the server. I could even put vlans on top of the bonding interface. However, only half the problem was solved: if I used srv1 as a client to the other servers, iperf was reporting around 940Mbps for each connection, and bwm-ng showed, of course, a nice distribution of the load between the two nics; if I run the iperf server on srv1 and tried to connect with the other servers, there was no load balancing. I thought that maybe I was out of luck and the hashes for the two mac addresses of the clients were the same, so I brought in two new servers and tested with the four of them at the same time, and still nothing changed. I tried disabling and reenabling one of the links, and all that happened was the traffic switched from one link to the other and back to the first again. I also tried setting the trunk to "plain trunk mode" on the switch, and experimented with other bonding modes (roundrobin, xor, alb, tlb) but I never saw any traffic distribution. One interesting thing, though: one of the four switches is a Cisco 2950, image version 12.1(22)EA7. It has 48 10/100 ports and 2 gigabit uplinks. I have a server (call it srv4) with a 4 channel trunk connected to it (4x100), FreeBSD 8.0 release. The switch is connected to sw0 via gigabit. If I set up an iperf server on one of the servers connected to sw0 and a client on srv4, ALL 4 links are used, and iperf reports around 330Mbps. systat -ifstat shows all four interfaces are used. The cisco port-channel uses src-mac to balance the load. The HP should use both the source and destination according to the manual, so it should work as well. Could this mean there is some bug in the HP firmware? Am I doing something wrong?

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• dojo.require() prevents Firefox from rendering the page

  - by Eduard Wirch

  Im experiencing strange behavior with Firefox and Dojo. I have a html page with these lines in the <head> section: ... <script type="text/javascript" src="dojo.js" djconfig="parseOnLoad: true, locale: 'de'"></script> <script type="text/javascript"> dojo.require("dojo.number"); </script> ... Sometimes the page loads normally. But sometimes it won't. Firefox will fetch the whole html page but not render it. I see only a gray window. After some experiments I figured out that the rendering problem has something to do with the load time of the html. Firefox starts evaluating the html page while loading it. If the page takes too long to load the above javascript will be executed BEFORE the html finishes loading. If this happens I'll get the gray window. Advising Firefox to show me the source code of the page will display the correct complete html code. BUT: if I save the page to disk (File-Save Page As...) the html code will be truncated and the above part will look like this: ... <script type="text/javascript" src="dojo.js" djconfig="parseOnLoad: true, locale: 'de'"></script> <script type="text/javascript"> dojo.require("dojo.number"); </script></head><body></body></html> This explains why I get to see a gray area. But why does this code appear there? I assume the require() method of Dojo does something "evil". But I can't figure out what. There is no write.document("</head><body></body></html>"); in the Dojo code. I checked for it. The problem would be fixed, if I'd place the dojo.require("dojo.number"); statement in the window.load event: <script type="text/javascript"> window.load=function() { dojo.require("dojo.number"); } </script> But I'm curious why this happens. Is there a Javasctript function which forces Firefox to stop evaluating the page? Does Dojo do somethig "bad"? Can anyone explain this behavior to me? EDIT: Dojo 1.3.1, no JS errors or warnings.

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• ASP.Net Web Farm Monitoring

  - by cisellis

  I am looking for suggestions on doing some simple monitoring of an ASP.Net web farm as close to real-time as possible. The objectives of this question are to: Identify the best way to monitor several Windows Server production boxes during short (minutes long) period of ridiculous load Receive near-real-time feedback on a few key metrics about each box. These are simple metrics available via WMI such as CPU, Memory and Disk Paging. I am defining my time constraints as soon as possible with 120 seconds delayed being the absolute upper limit. Monitor whether any given box is up (with "up" being defined as responding web requests in a reasonable amount of time) Here are more details, things I've tried, etc. I am not interested in logging. We have logging solutions in place. I have looked at solutions such as ELMAH which don't provide much in the way of hardware monitoring and are not visible across an entire web farm. ASP.Net Health Monitoring is too broad, focuses too much on logging and is not acceptable for deep analysis. We are on Amazon Web Services and we have looked into CloudWatch. It looks great but messages in the forum indicate that the metrics are often a few minutes behind, with one thread citing 2 minutes as the absolute soonest you could expect to receive the feedback. This would be good to have for later analysis but does not help us real-time Stuff like JetBrains profiler is good for testing but again, not helpful during real-time monitoring. The closest out-of-box solution I've seen is Nagios which is free and appears to measure key indicators on any kind of box, including Windows. However, it appears to require a Linux box to run itself on and a good deal of manual configuration. I'd prefer to not spend my time mining config files and then be up a creek when it fails in production since Linux is not my main (or even secondary) environment. Are there any out-of-box solutions that I am missing? Obviously a windows-based solution that is easy to setup is ideal. I don't require many bells and whistles. In the absence of an out-of-box solution, it seems easy for me to write something simple to handle what I need. I've been thinking a simple client-server setup where the server requests a few WMI metrics from each client over http and sticks them in a database. We could then monitor the metrics via a query or a dashboard or something. If the client doesn't respond, it's effectively down. Any problems with this, best practices, or other ideas? Thanks for any help/feedback.

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• Modern Java alternatives

  - by Ralph

  I'm not sure if stackoverflow is the best forum for this discussion. I have been a Java developer for 14 years and have written an enterprise-level (~500,000 line) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for the stackoverflow readerships' opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. If anyone has a suggestion for another JVM-based language that can be used for enterprise level development, please list it. Also, it is not my intent to start a flame war. Thanks, Ralph

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• Is this question too hard for a seasoned C++ architect?

  - by Monomer

  Background Information We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++. The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence. Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test. After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs) My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question. The Question There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j. class C { public: int foo() {...} int boo() {...} int boo_and_foo() {...} int foo_and_boo() {...} }; In code one might write: C c; . . int i = c.foo() + c.boo(); But it would be better to have: int i = c.foo_and_boo(); What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter. Note that foo and boo are not commutative. Possible Solution We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail. We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more. Is this really a difficult question? Should it be removed? Or are we just not seeing the right candidates?

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• Converting AES encryption token code in C# to php

  - by joey

  Hello, I have the following .Net code which takes two inputs. 1) A 128 bit base 64 encoded key and 2) the userid. It outputs the AES encrypted token. I need the php equivalent of the same code, but dont know which corresponding php classes are to be used for RNGCryptoServiceProvider,RijndaelManaged,ICryptoTransform,MemoryStream and CryptoStream. Im stuck so any help regarding this would be really appreciated. using System; using System.Text; using System.IO; using System.Security.Cryptography; class AESToken { [STAThread] static int Main(string[] args) { if (args.Length != 2) { Console.WriteLine("Usage: AESToken key userId\n"); Console.WriteLine("key Specifies 128-bit AES key base64 encoded supplied by MediaNet to the partner"); Console.WriteLine("userId specifies the unique id"); return -1; } string key = args[0]; string userId = args[1]; StringBuilder sb = new StringBuilder(); // This example code uses the magic string “CAMB2B”. The implementer // must use the appropriate magic string for the web services API. sb.Append("CAMB2B"); sb.Append(args[1]); // userId sb.Append('|'); // pipe char sb.Append(System.DateTime.UtcNow.ToString("yyyy-MM-dd HH:mm:ssUTC")); //timestamp Byte[] payload = Encoding.ASCII.GetBytes(sb.ToString()); byte[] salt = new Byte[16]; // 16 bytes of random salt RNGCryptoServiceProvider rng = new RNGCryptoServiceProvider(); rng.GetBytes(salt); // the plaintext is 16 bytes of salt followed by the payload. byte[] plaintext = new byte[salt.Length + payload.Length]; salt.CopyTo(plaintext, 0); payload.CopyTo(plaintext, salt.Length); // the AES cryptor: 128-bit key, 128-bit block size, CBC mode RijndaelManaged cryptor = new RijndaelManaged(); cryptor.KeySize = 128; cryptor.BlockSize = 128; cryptor.Mode = CipherMode.CBC; cryptor.GenerateIV(); cryptor.Key = Convert.FromBase64String(args[0]); // the key byte[] iv = cryptor.IV; // the IV. // do the encryption ICryptoTransform encryptor = cryptor.CreateEncryptor(cryptor.Key, iv); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write); cs.Write(plaintext, 0, plaintext.Length); cs.FlushFinalBlock(); byte[] ciphertext = ms.ToArray(); ms.Close(); cs.Close(); // build the token byte[] tokenBytes = new byte[iv.Length + ciphertext.Length]; iv.CopyTo(tokenBytes, 0); ciphertext.CopyTo(tokenBytes, iv.Length); string token = Convert.ToBase64String(tokenBytes); Console.WriteLine(token); return 0; } } Please help. Thank You.

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• Simple Convention Automapper for two-way Mapping (Entities to/from ViewModels)

  - by Omu

  UPDATE: this stuff has evolved into a nice project, see it at http://valueinjecter.codeplex.com check this out, I just wrote a simple automapper, it takes the value from the property with the same name and type of one object and puts it into another, and you can add exceptions (ifs, switch) for each type you may need so tell me what do you think about it ? I did it so I could do something like this: Product –> ProductDTO ProductDTO –> Product that's how it begun: I use the "object" type in my Inputs/Dto/ViewModels for DropDowns because I send to the html a IEnumerable<SelectListItem> and I receive a string array of selected keys back public void Map(object a, object b) { var pp = a.GetType().GetProperties(); foreach (var pa in pp) { var value = pa.GetValue(a, null); // property with the same name in b var pb = b.GetType().GetProperty(pa.Name); if (pb == null) { //no such property in b continue; } if (pa.PropertyType == pb.PropertyType) { pb.SetValue(b, value, null); } } } UPDATE: the real usage: the Build methods (Input = Dto): public static TI BuildInput<TI, T>(this T entity) where TI: class, new() { var input = new TI(); input = Map(entity, input) as TI; return input; } public static T BuildEntity<T, TI, TR>(this TI input) where T : class, new() where TR : IBaseAdvanceService<T> { var id = (long)input.GetType().GetProperty("Id").GetValue(input, null); var entity = LocatorConfigurator.Resolve<TR>().Get(id) ?? new T(); entity = Map(input, entity) as T; return entity; } public static TI RebuildInput<T, TI, TR>(this TI input) where T: class, new() where TR : IBaseAdvanceService<T> where TI : class, new() { return input.BuildEntity<T, TI, TR>().BuildInput<TI, T>(); } in the controller: public ActionResult Create() { return View(new Organisation().BuildInput<OrganisationInput, Organisation>()); } [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(OrganisationInput o) { if (!ModelState.IsValid) { return View(o.RebuildInput<Organisation,OrganisationInput, IOrganisationService>()); } organisationService.SaveOrUpdate(o.BuildEntity<Organisation, OrganisationInput, IOrganisationService>()); return RedirectToAction("Index"); } The real Map method public static object Map(object a, object b) { var lookups = GetLookups(); var propertyInfos = a.GetType().GetProperties(); foreach (var pa in propertyInfos) { var value = pa.GetValue(a, null); // property with the same name in b var pb = b.GetType().GetProperty(pa.Name); if (pb == null) { continue; } if (pa.PropertyType == pb.PropertyType) { pb.SetValue(b, value, null); } else if (lookups.Contains(pa.Name) && pa.PropertyType == typeof(LookupItem)) { pb.SetValue(b, (pa.GetValue(a, null) as LookupItem).GetSelectList(pa.Name), null); } else if (lookups.Contains(pa.Name) && pa.PropertyType == typeof(object)) { pb.SetValue(b, pa.GetValue(a, null).ReadSelectItemValue(), null); } else if (pa.PropertyType == typeof(long) && pb.PropertyType == typeof(Organisation)) { pb.SetValue(b, pa.GetValue<long>(a).ReadOrganisationId(), null); } else if (pa.PropertyType == typeof(Organisation) && pb.PropertyType == typeof(long)) { pb.SetValue(b, pa.GetValue<Organisation>(a).Id, null); } } return b; }

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• Manipulating matrix operations (transpose, negation, addition, and mutiplication) using functions in

  - by user292489

  I was trying to manipulate matrices in my input file using functions. My input file is: A 3 3 1 2 3 4 5 6 7 8 9 B 3 3 1 0 0 0 1 0 0 0 1 C 2 3 3 5 8 -1 -2 -3 D 3 5 0 0 0 1 0 1 0 1 0 1 0 1 0 0 1 E 1 1 10 F 3 10 1 0 2 0 3 0 4 0 5 0 0 2 3 -1 -3 -4 -3 8 3 7 0 0 0 4 6 5 8 2 -1 10 I am having trouble in implementing the functions that I declared. I assumed my program will perform those operations: transpose, negate, add, and multiply matices according to the users choice: /* once this program is compiled and executed, it will perform the basic matrix * operations: negation, transpose, addition, and multiplication. */ #include <stdio.h> #include <stdlib.h> #define MAX 10 int readmatrix(FILE *input, char martixname[6],int , mat[10][10], int i, int j); void printmatrix(char matrixname[6], int mat[10][10], int i, int j); void Negate(char matrixname[6], int mat[10][10], int i, int j); void add(char matrixname[6], int mat[10][10],int i, int k); void multiply(char matrixname[], int mat[][10], char A[], int i, int k); void transpose (char matrixname[], int mat[][10], char A[], int); void printT(int mat[][10], int); int selctoption(); char selectmatrix(); int main(int argc, char *argv[]) { char matrixtype[6]; int mat[][10]; FILE *filein; int size; int optionop; int matrixop; int option; if (argc != 2) { printf("Usage: executable input.\n"); exit(0); } filein = fopen(argv[1], "r"); if (!filein) { printf("ERROR: input file not found.\n"); exit (0); } size = readmatrix (filein, matrixtype); printmatrix(matrix[][10], size); option = selectoption(); matrixtype = selectmatrix(); //printf("You have: %5.2f ", deposit); optionop = readmatrix(option, matrix[][10], size); if (choiceop == 6) { printf("Thanks for using the matrix operation program.\n"); exit(0); } printf("Please select from the following matrix operations:\n") printf("\t1. Print matrix\n"); printf("\t2. Negate matrix\n"); printf("\t3. Transpose matrix\n"); printf("\t4. Add matrices\n"); printf("\t5. Multiply matrices\n"); printf("\t6. Quit\n"); fclose(filein); return 0; } do { printf("Please select option(1-%d):", optionop); scanf("%d", &matrixop); } while(matrixop <= 0 || matrixop > optionop); void readmatrix (FILE *in, int mat[][10], char A[], int i, int j) { int i=0,j = 0; while (fscanf(in, "%d", &mat[i][j]) != EOF) return 0; } // I would appreciate anyone's feedback.

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• Modeling distribution of performance measurements

  - by peterchen

  How would you mathematically model the distribution of repeated real life performance measurements - "Real life" meaning you are not just looping over the code in question, but it is just a short snippet within a large application running in a typical user scenario? My experience shows that you usually have a peak around the average execution time that can be modeled adequately with a Gaussian distribution. In addition, there's a "long tail" containing outliers - often with a multiple of the average time. (The behavior is understandable considering the factors contributing to first execution penalty). My goal is to model aggregate values that reasonably reflect this, and can be calculated from aggregate values (like for the Gaussian, calculate mu and sigma from N, sum of values and sum of squares). In other terms, number of repetitions is unlimited, but memory and calculation requirements should be minimized. A normal Gaussian distribution can't model the long tail appropriately and will have the average biased strongly even by a very small percentage of outliers. I am looking for ideas, especially if this has been attempted/analysed before. I've checked various distributions models, and I think I could work out something, but my statistics is rusty and I might end up with an overblown solution. Oh, a complete shrink-wrapped solution would be fine, too ;) Other aspects / ideas: Sometimes you get "two humps" distributions, which would be acceptable in my scenario with a single mu/sigma covering both, but ideally would be identified separately. Extrapolating this, another approach would be a "floating probability density calculation" that uses only a limited buffer and adjusts automatically to the range (due to the long tail, bins may not be spaced evenly) - haven't found anything, but with some assumptions about the distribution it should be possible in principle. Why (since it was asked) - For a complex process we need to make guarantees such as "only 0.1% of runs exceed a limit of 3 seconds, and the average processing time is 2.8 seconds". The performance of an isolated piece of code can be very different from a normal run-time environment involving varying levels of disk and network access, background services, scheduled events that occur within a day, etc. This can be solved trivially by accumulating all data. However, to accumulate this data in production, the data produced needs to be limited. For analysis of isolated pieces of code, a gaussian deviation plus first run penalty is ok. That doesn't work anymore for the distributions found above. [edit] I've already got very good answers (and finally - maybe - some time to work on this). I'm starting a bounty to look for more input / ideas.

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• mciSendString cannot save to directory path

  - by robUK

  Hello, VS C# 2008 SP1 I have a created a small application that records and plays audio. However, my application needs to save the wave file to the application data directory on the users computer. The mciSendString takes a C style string as a parameter and has to be in 8.3 format. However, my problem is I can't get it to save. And what is strange is sometime it does and sometimes it doesn't. Howver, most of the time is failes. However, if I save directly to the C drive it works first time everything. I have used 3 different methods that I have coded below. The error number that I get when it fails is 286."The file was not saved. Make sure your system has sufficient disk space or has an intact network connection" Many thanks for any suggestins, [DllImport("winmm.dll",CharSet=CharSet.Auto)] private static extern uint mciSendString([MarshalAs(UnmanagedType.LPTStr)] string command, StringBuilder returnValue, int returnLength, IntPtr winHandle); [DllImport("winmm.dll", CharSet = CharSet.Auto)] private static extern int mciGetErrorString(uint errorCode, StringBuilder errorText, int errorTextSize); [DllImport("Kernel32.dll", CharSet=CharSet.Auto)] private static extern int GetShortPathName([MarshalAs(UnmanagedType.LPTStr)] string longPath, [MarshalAs(UnmanagedType.LPTStr)] StringBuilder shortPath, int length); // Stop recording private void StopRecording() { // Save recorded voice string shortPath = this.shortPathName(); string formatShortPath = string.Format("save recsound \"{0}\"", shortPath); uint result = 0; StringBuilder errorTest = new StringBuilder(256); // C:\DOCUME~1\Steve\APPLIC~1\Test.wav // Fails result = mciSendString(string.Format("{0}", formatShortPath), null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // command line convention - fails result = mciSendString("save recsound \"C:\\DOCUME~1\\Steve\\APPLIC~1\\Test.wav\"", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // 8.3 short format - fails result = mciSendString(@"save recsound C:\DOCUME~1\Steve\APPLIC~1\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); // Save to C drive works everytime. result = mciSendString(@"save recsound C:\Test.wav", null, 0, IntPtr.Zero); mciGetErrorString(result, errorTest, errorTest.Length); mciSendString("close recsound ", null, 0, IntPtr.Zero); } // Get the short path name so that the mciSendString can save the recorded wave file private string shortPathName() { string shortPath = string.Empty; long length = 0; StringBuilder buffer = new StringBuilder(256); // Get the length of the path length = GetShortPathName(this.saveRecordingPath, buffer, 256); shortPath = buffer.ToString(); return shortPath; }

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• Global Entity Framework Context in WPF Application

  - by OffApps Cory

  Good day, I am in the middle of development of a WPF application that is using Entity Framework (.NET 3.5). It accesses the entities in several places throughout. I am worried about consistency throughout the application in regard to the entities. Should I be instancing separate contexts in my different views, or should I (and is a a good way to do this) instance a single context that can be accessed globally? For instance, my entity model has three sections, Shipments (with child packages and further child contents), Companies/Contacts (with child addresses and telephones), and disk specs. The Shipments and EditShipment views access the DiskSpecs, and the OptionsView manages the DiskSpecs (Create, Edit, Delete). If I edit a DiskSpec, I have to have something in the ShipmentsView to retrieve the latest specs if I have separate contexts right? If it is safe to have one overall context from which the rest of the app retrieves it's objects, then I imagine that is the way to go. If so, where would that instance be put? I am using VB.NET, but I can translate from C# pretty good. Any help would be appreciated. I just don't want one of those applications where the user has to hit reload a dozen times in different parts of the app to get the new data. Update: OK so I have changed my app as follows: All contexts are created in Using Blocks to dispose of them after they are no longer needed. When loaded, all entities are detatched from context before it is disposed. A new property in the MainViewModel (ContextUpdated) raises an event that all of the other ViewModels subscribe to which runs that ViewModels RefreshEntities method. After implementing this, I started getting errors saying that an entity can only be referenced by one ChangeTracker at a time. Since I could not figure out which context was still referencing the entity (shouldn't be any context right?) I cast the object as IEntityWithChangeTracker, and set SetChangeTracker to nothing (Null). This has let to the current problem: When I Null the changeTracker on the Entity, and then attach it to a context, it loses it's changed state and does not get updated to the database. However if I do not null the change tracker, I can't attach. I have my own change tracking code, so that is not a problem. My new question is, how are you supposed to do this. A good example Entity query and entity save code snipped would go a long way, cause I am beating my head in trying to get what I once thought was a simple transaction to work. Any help would elevate you to near god-hood.

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