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• Triangulation in 3D Space

  - by w3b_wizzard

  Disclaimer: This is for class, however I'm fresh out of ideas and a nudge in the right direction would be much appreciated. Also, this needs to be implemented in raw C, so no fancy libraries can be used. I have to write a search and rescue simulator for submarines, it has to find a probe that is randomly placed in 3D space in a grid from of the MAX_XYZ (100000). The only tools I'm given are a "ping" which will give the magnitude of the distance between a certain sub and the probe. The goal is to optimize the costs of this entire operation so a brute force attempt, like looking at every single coordinate, won't work. Hence I was thinking triangulation. Now, it makes loads of sense to me, place three subs, each one of them uses their ping to get the distance between them and the probe. Since each sub have a known distance relative to one another, it's easy to build the base of a tetrahedron with them, and the results of the ping will point to a certain coordinate, the problem I'm having is how to figure out the elevation, or the height, of the tetrahedron. So what I have as data is the following: Distances between subs (In vector format) Angles between each subs (very easy to compute) Distance between each sub and the probe (3 segments from the base to the peak) Angles inside each of the outer 3 surfaces of the tetrahedron. I tried finding some sort of relationship with the vertices of the tetrahedron and the relative angles in each of them, however all I found had to deal with tetrahedrons built with equilateral triangles, which isn't much help. I have the impression this can be easily solved with trig but either I'm not seeing it or I need more coffee. Any suggestions would be appreciated!

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• C++: Calculate probability percentage during each iteration

  - by Mur Quirk

  Can't seem to get this to work. The idea is to calculate the percentage of heads and tails after each count, accumulating after each iteration. Except I keep getting nan% for my calculations. Anybody see what I'm doing wrong? void flipCoin(time_t seconds, int flipCount){ vector<int> flips; float headCount = 0; float tailCount = 0; double headProbability = double((headCount/(headCount + tailCount))*100); double tailProbability = double((tailCount/(headCount + tailCount))*100); for (int i=0; i < flipCount; i++) { int flip = rand() % (HEADS - TAILS + 1) + TAILS; flips.push_back(flip); if (flips[i] == 1) { tailCount++; cout << "Tail Percent: " << tailProbability << "%" << endl; }else{ headCount++; cout << "Head Percent: " << headProbability << "%" << endl; } } }

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• matching certain numbers at the end of a string

  - by user697473

  I have a vector of strings: s <- c('abc1', 'abc2', 'abc3', 'abc11', 'abc12', 'abcde1', 'abcde2', 'abcde3', 'abcde11', 'abcde12', 'nonsense') I would like a regular expression to match only the strings that begin with abc and end with 3, 11, or 12. In other words, the regex has to exclude abc1 but not abc11, abc2 but not abc12, and so on. I thought that this would be easy to do with lookahead assertions, but I haven't found a way. Is there one? EDIT: Thanks to posters below for pointing out a serious ambiguity in the original post. In reality, I have many strings. They all end in digits: some in 0, some in 9, some in the digits in between. I am looking for a regex that will match all strings except those that end with a letter followed by a 1 or a 2. (The regex should also match only those strings that start with abc, but that's an easy problem.) I tried to use negative lookahead assertions to create such a regex. But I didn't have any success.

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• ggplot: showing % instead of counts in charts of categorical variables

  - by wishihadabettername

  I'm plotting a categorical variable and instead of showing the counts for each category value, I'm looking for a way to get ggplot to display the percentage of values in that category. Of course, it is possible to create another variable with the calculated percentage and plot that one, but I have to do it several dozens of times and I hope to achieve that in one command. I was experimenting with something like qplot (mydataf) + stat_bin(aes(n=nrow(mydataf), y=..count../n)) + scale_y_continuous(formatter="percent") but I must be using it incorrectly, as I got errors. To easily reproduce the setup, here's a simplified example: mydata <- c ("aa", "bb", null, "bb", "cc", "aa", "aa", "aa", "ee", null, "cc"); mydataf <- factor(mydata); qplot (mydataf); #this shows the count, I'm looking to see % displayed. In the real case I'll probably use ggplot instead of qplot, but the right way to use stat_bin still eludes me. Thank you. UPDATE: I've also tried these four approaches: ggplot(mydataf, aes(y = (..count..)/sum(..count..))) + scale_y_continuous(formatter = 'percent'); ggplot(mydataf, aes(y = (..count..)/sum(..count..))) + scale_y_continuous(formatter = 'percent') + geom_bar(); ggplot(mydataf, aes(x = levels(mydataf), y = (..count..)/sum(..count..))) + scale_y_continuous(formatter = 'percent'); ggplot(mydataf, aes(x = levels(mydataf), y = (..count..)/sum(..count..))) + scale_y_continuous(formatter = 'percent') + geom_bar(); but all 4 give: Error: ggplot2 doesn't know how to deal with data of class factor The same error appears for the simple case of ggplot (data=mydataf, aes(levels(mydataf))) + geom_bar() so it's clearly something about how ggplot interacts with a single vector. I'm scratching my head, googling for that error gives a single result.

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• C++ Function pointers vs Switch

  - by Perfix

  What is faster: Function pointers or switch? The switch statement would have around 30 cases, consisting of enumarated unsigned ints from 0 to 30. I could do the following: class myType { FunctionEnum func; string argv[123]; int someOtherValue; }; // In another file: myType current; // Iterate through a vector containing lots of myTypes // ... for ( i=0; i < myVecSize; i ++ ) switch ( current.func ) { case 1: //... break; // ........ case 30: // blah break; } And go trough the switch with func every time. The good thing about switch would also be that my code is more organized than with 30 functions. Or I could do that (not so sure with that): class myType { myReturnType (*func); string argv[123]; int someOtherValue; }; I'd have 30 different functions then, at the beginning a pointer to one of them is assigned to myType. What is probably faster: Switch statement or function pointer? Calls per second: Around 10 million. I can't just test it out - that would require me to rewrite the whole thing. Currently using switch. I'm building an interpreter which I want to be faster than Python & Ruby - every clock cycle matters!

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• Const Discards Qualifers: C++

  - by user991673

  I'm using OpenGL to render camera perspectives, and a one point in my code I'm trying to take the direction of the light (shown here as type "Vector4") and multiply it by a matrix of type "Matrix4x4" that represents the Modelview transformation (sorry if this is not making any sense, this is for a school project, as such I'm still learning about this stuff) Anyway, my code goes as follows... Vector4 lightDirection = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); data->dir = lightDirection; setLight(*data); this give me the following error: passing 'const vec4<double>' as 'this' argument of 'vec4<T>& vec4<T>::operator=(const vec4<T>&)[with T = double]' discards qualifiers Again, much of this code is prewritten for the class (namely the vector and matrix types) but if someone could just help me decipher what the error means it would be much appreciated! I can give more information as needed. I figured 'data' or 'data-dir' were const, however I can find no mention of either of them to be. 'dir' is of type SceneLightData, and when its added on I'm doing this: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData light = sceneLight; m_lights.push_back(&light); } The error occurs on this line: data->dir = lightDirection; EDIT problem solved. thanks everyone! solution: void Scene::addLight(const SceneLightData &sceneLight) { SceneLightData* light = new SceneLightData; *light = sceneLight; m_lights.push_back(light); } and SceneLightData* data = m_lights[i]; data->dir = data->dir * follow->getModelviewMatrix().getInverse().getTranspose(); setLight(*data);

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• Problems Expanding an Array in C++

  - by dxq

  I'm writing a simulation for class, and part of it involves the reproduction of organisms. My organisms are kept in an array, and I need to increase the size of the array when they reproduce. Because I have multiple classes for multiple organisms, I used a template: template <class orgType> void expandarray(orgType* oldarray, int& numitems, int reproductioncount) { orgType *newarray = new orgType[numitems+reproductioncount]; for (int i=0; i<numitems; i++) { newarray[i] = oldarray[i]; } numitems += reproductioncount; delete[] oldarray; oldarray = newarray; newarray = NULL; } However, this template seems to be somehow corrupting my data. I can run the program fine without reproduction (commenting out the calls to expandarray), but calling this function causes my program to crash. The program does not crash DURING the expandarray function, but crashes on access violation later on. I've written functions to expand an array hundreds of times, and I have no idea what I screwed up this time. Is there something blatantly wrong in my function? Does it look right to you? EDIT: Thanks for everyone's help. I can't believe I missed something so obvious. In response to using std::vector: we haven't discussed it in class yet, and as silly as it seems, I need to write code using the methods we've been taught.

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• What influences running time of reading a bunch of images?

  - by remi

  I have a program where I read a handful of tiny images (50000 images of size 32x32). I read them using OpenCV imread function, in a program like this: std::vector<std::string> imageList; // is initialized with full path to the 50K images for(string s : imageList) { cv::Mat m = cv::imread(s); } Sometimes, it will read the images in a few seconds. Sometimes, it takes a few minutes to do so. I run this program in GDB, with a breakpoint further away than the loop for reading images so it's not because I'm stuck in a breakpoint. The same "erratic" behaviour happens when I run the program out of GDB. The same "erratic" behaviour happens with program compiled with/without optimisation The same "erratic" behaviour happens while I have or not other programs running in background The images are always at the same place in the hard drive of my machine. I run the program on a Linux Suse distrib, compiled with gcc. So I am wondering what could affect the time of reading the images that much?

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• C++, inject additional data in a method

  - by justik

  I am adding the new modul in some large library. All methods here are implemented as static. Let mi briefly describe the simplified model: typedef std::vector<double> TData; double test ( const TData &arg ) { return arg ( 0 ) * sin ( arg ( 1 ) + ...;} double ( * p_test ) ( const TData> &arg) = &test; class A { public: static T f1 (TData &input) { .... //some computations B::f2 (p_test); } }; Inside f1() some computations are perfomed and a static method B::f2 is called. The f2 method is implemented by another author and represents some simulation algorithm (example here is siplified). class B { public: static double f2 (double ( * p_test ) ( const TData &arg ) ) { //difficult algorithm working p_test many times double res = p_test(arg); } }; The f2 method has a pointer to some weight function (here p_test). But in my case some additional parameters computed in f1 for test() methods are required double test ( const TData &arg, const TData &arg2, char *arg3.... ) { } How to inject these parameters into test() (and so to f2) to avoid changing the source code of the f2 methods (that is not trivial), redesign of the library and without dirty hacks :-) ? The most simple step is to override f2 static double f2 (double ( * p_test ) ( const TData &arg ), const TData &arg2, char *arg3.... ) But what to do later? Consider, that methods are static, so there will be problems with objects. Thanks for your help.

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• reading keyboard input without "consuming" it in x86 assembly

  - by Bob

  Ok so here the deal: I have an assignment regarding DOS and interrupts: I need to write a sort of key-logger function that can be called from C code. what it means is a c program would call an assembly function called startlog that would indicate to start logging the keys pressed until a function called endlog is called. the logging should work like this: write the ascii value of any key pressed without disturbing the C code between startlog and endlog, meaning that if the C code also needs to read the input (let's say by scanf, it would work ok). I managed to write the logger by changing the interrupt vector 9th entry (interrupt for keyboard press) to a function I wrote that writes the values to a file, and it works fine. however the C code does not get the input. Basically what i did is read the key pressed using int 21h, however after reading the ascii value it is "consumed" so I need a way to either simulate the key press again or read the value without "consuming" it so next time a key is read it reads the same key. (I described the code in english because it is long and clumsy assembly code)

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• CArray doesn't call copy constructors on memory reallocations, now what?

  - by MMx

  Suppose I have a class that requires copy constructor to be called to make a correct copy of: struct CWeird { CWeird() { number = 47; target = &number; } CWeird(const CWeird &other) : number(other.number), target(&number) { } void output() { printf("%d %d\n", *target, number); } int *target, number; }; Now the trouble is that CArray doesn't call copy constructors on its elements when reallocating memory (only memcpy from the old memory to the new), e.g. this code CArray<CWeird> a; a.SetSize(1); a[0].output(); a.SetSize(2); a[0].output(); results in 47 47 -572662307 47 I don't get this. Why is it that std::vector can copy the same objects properly and CArray can't? What's the lesson here? Should I use only classes that don't require explicit copy constructors? Or is it a bad idea to use CArray for anything serious?

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• c++ problem, maybe with types...

  - by Infinity

  Hi guys! I have a little problem in my code. The variables don't want to change their values. Can you say why? Here is my code: vector<coordinate> rocks(N); double angle; double x, y; // other code while (x > 1.0 || x < -1.0 || y > 1.0 || y < -1.0) { angle = rand() * 2.0 * M_PI; cout << angle << endl; cout << rocks[i - 1].x << endl; cout << rocks[i - 1].y << endl; x = rocks[i-1].x + r0 * cos(angle); y = rocks[i-1].y + r0 * sin(angle); cout << x << endl; cout << y << endl << endl; } // other code And the result on the console is: 6.65627e+09 0.99347 0.984713 1.09347 0.984713 1.16964e+09 0.99347 0.984713 1.09347 0.984713 As you see the values of x, y variables doesn't change and this while be an infinity loop. What's the problem? What do you think?

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• deleting an array that stores pointers to some objects

  - by memC

  hi, I am storing pointers to elements of a vec_A in an array A* a_ptrs[3] . Assume that vec_A will not be resized. So, a_ptrs[i] will point to the correct element. My question is: Suppose A* a_ptrs[3] is declared in a class B. Since it is not created using 'new' I am guessing I don't need to delete it in the destructor. Am I right?? class A { public: int getNumber(); A(int val); ~A(){}; private: int num; }; A::A(int val){ num = val; }; int A::getNumber(){ return num; }; int main(){ int i =0; int num; std::vector<A> vec_A; for ( i = 0; i < 10; i++){ vec_A.push_back(A(i)); } A* a_ptrs[3]; a_ptrs[0] = &vec_A[0]; a_ptrs[1] = &vec_A[3]; a_ptrs[2] = &vec_A[5]; for (i = 0; i<3; i++){ std::cout<<"\n: a_ptrs[i].getNumber() = "<<a_ptrs[i]->getNumber(); } std::cout << "\nPress RETURN to continue..."; std::cin.get(); return 0; }

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• 3D coordinate of 2D point given camera and view plane

  - by Myx

  I wish to generate rays from the camera through the viewing plane. In order to do this, I need my camera position ("eye"), the up, right, and towards vectors (where towards is the vector from the camera in the direction of the object that the camera is looking at) and P, the point on the viewing plane. Once I have these, the ray that's generated is: ray = camera_eye + t*(P-camera_eye); where t is the distance along the ray (assume t = 1 for now). My question is, how do I obtain the 3D coordinates of point P given that it is located at position (i,j) on the viewing plane? Assume that the upper left and lower right corners of the viewing plane are given. NOTE: The viewing plane is not actually a plane in the sense that it doesn't extend infinitely in all directions. Rather, one may think of this plane as a widthxheight image. In the x direction, the range is 0--width and in the y direction the range is 0--height. I wish to find the 3D coordinate of the (i,j)th element, 0

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• getline with ints C++

  - by Mdjon26

  I have a file 0 3 2 1 2 3 4 5 6 6 8 1 Where the first number for each line is the row, the second number is the column, and the third number is the data contained in that row, column. This will be a given [8][8] array so I have already initialized everything to 0, but how can I store each of these data values? For example, I want [0][3] =2 and [1][2] = 3. I would like to keep track of the line on which I found that row, col, and data value. So, how can I correctly insert these values into my 2-D array? int rowcol[8][8]; for (int i=0; i < 9; i++) for (int j=0; j < 9; j++) { rowcol[i][j] =0; } ifstream myfile; int nums; myfile.open(text.c_str()); while (!myfile.eof()) { myfile >> nums; numbers.push_back(nums); } for (int i=0; i < numbers.size(); i++) { //Not sure what the best approach here would be and I'm not even sure if I should have done a vector... }

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• method works fine, until it is called in a function, then UnboundLocalError

  - by user1776100

  I define a method called dist, to calculate the distance between two points which I does it correctly when directly using the method. However, when I get a function to call it to calculate the distance between two points, I get UnboundLocalError: local variable 'minkowski_distance' referenced before assignment edit sorry, I just realised, this function does work. However I have another method calling it that doesn't. I put the last method at the bottom This is the method: class MinkowskiDistance(Distance): def __init__(self, dist_funct_name_str = 'Minkowski distance', p=2): self.p = p def dist(self, obj_a, obj_b): distance_to_power_p=0 p=self.p for i in range(len(obj_a)): distance_to_power_p += abs((obj_a[i]-obj_b[i]))**(p) minkowski_distance = (distance_to_power_p)**(1/p) return minkowski_distance and this is the function: (it basically splits the tuples x and y into their number and string components and calculates the distance between the numeric part of x and y and then the distance between the string parts, then adds them. def total_dist(x, y, p=2, q=2): jacard = QGramDistance(q=q) minkowski = MinkowskiDistance(p=p) x_num = [] x_str = [] y_num = [] y_str = [] #I am spliting each vector into its numerical parts and its string parts so that the distances #of each part can be found, then summed together. for i in range(len(x)): if type(x[i]) == float or type(x[i]) == int: x_num.append(x[i]) y_num.append(y[i]) else: x_str.append(x[i]) y_str.append(y[i]) num_dist = minkowski.dist(x_num,y_num) str_dist = I find using some more steps #I am simply adding the two types of distance to get the total distance: return num_dist + str_dist class NearestNeighbourClustering(Clustering): def __init__(self, data_file, clust_algo_name_str='', strip_header = "no", remove = -1): self.data_file= data_file self.header_strip = strip_header self.remove_column = remove def run_clustering(self, max_dist, p=2, q=2): K = {} #dictionary of clusters data_points = self.read_data_file() K[0]=[data_points[0]] k=0 #I added the first point in the data to the 0th cluster #k = number of clusters minus 1 n = len(data_points) for i in range(1,n): data_point_in_a_cluster = "no" for c in range(k+1): distances_from_i = [total_dist(data_points[i],K[c][j], p=p, q=q) for j in range(len(K[c]))] d = min(distances_from_i) if d <= max_dist: K[c].append(data_points[i]) data_point_in_a_cluster = "yes" if data_point_in_a_cluster == "no": k += 1 K[k]=[data_points[i]] return K

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• why Floating point exception?

  - by livio8495

  I have a floating point exception, and I don't know why. the code is this: void calcola_fitness(){ vector<double> fitness; int n=nodes.size(); int e=edges.size(); int dim=feasibility.size(); int feas=(feasibility[dim-1])*100; int narchi=numarchicoll[dim-1]/e; int numero_nodi=freePathNode.size()/n; double dist_start_goal=node_dist(0,1); int i,f,t; double pathlenght=0; int siize=freePathNode.size(); for(i=0;i!=siize-1; i++){ f=freePathNode[i].getIndex(); i++; t=freePathNode[i].getIndex(); i--; pathlenght=pathlenght+node_dist(f,t); } double pathlenghtnorm=pathlenght/10*dist_start_goal; double fit=((double)numero_nodi+pathlenghtnorm+(double)narchi)*((double)feas); fitness.push_back(fit); } Could anybody help me? What's the problem? I could I solve this? thank you very much

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• [c++/STL] Selective iterator

  - by rubenvb

  FYI: no boost, yes it has this, I want to reinvent the wheel ;) Is there some form of a selective iterator (possible) in C++? What I want is to seperate strings like this: some:word{or other to a form like this: some : word { or other I can do that with two loops and find_first_of(":") and ("{") but this seems (very) inefficient to me. I thought that maybe there would be a way to create/define/write an iterator that would iterate over all these values with for_each. I fear this will have me writing a full-fledged custom way-too-complex iterator class for a std::string. So I thought maybe this would do: std::vector<size_t> list; size_t index = mystring.find(":"); while( index != std::string::npos ) { list.push_back(index); index = mystring.find(":", list.back()); } std::for_each(list.begin(), list.end(), addSpaces(mystring)); This looks messy to me, and I'm quite sure a more elegant way of doing this exists. But I can't think of it. Anyone have a bright idea? Thanks PS: I did not test the code posted, just a quick write-up of what I would try

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• C# .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• Benchmark Linq2SQL, Subsonic2, Subsonic3 - Any other ideas to make them faster ?

  - by Aristos

  I am working with Subsonic 2 more than 3 years now... After Linq appears and then Subsonic 3, I start thinking about moving to the new Linq futures that are connected to sql. I must say that I start move and port my subsonic 2 with SubSonic 3, and very soon I discover that the speed was so slow thats I didn't believe it - and starts all that tests. Then I test Linq2Sql and see also a delay - compare it with Subsonic 2. My question here is, especial for the linq2sql, and the up-coming dotnet version 4, what else can I do to speed it up ? What else on linq2sql settings, or classes, not on this code that I have used for my messures I place here the project that I make the tests, also the screen shots of the results. How I make the tests - and the accurate of my measures. I use only for my question Google chrome, because its difficult for me to show here a lot of other measures that I have done with more complex programs. This is the most simple one, I just measure the Data Read. How can I prove that. I make a simple Thread.Sleep(10 seconds) and see if I see that 10 seconds on Google Chrome Measure, and yes I see it. here are more test with this Sleep thead to see whats actually Chrome gives. 10 seconds delay 100 ms delay Zero delay There is only a small 15ms thats get on messure, is so small compare it with the rest of my tests that I do not care about. So what I measure I measure just the data read via each method - did not count the data or database delay, or any disk read or anything like that. Later on the image with the result I show that no disk activity exist on the measures See this image to see what really I measure and if this is correct Why I chose this kind of test Its simple, it's real, and it's near my real problem that I found the delay of subsonic 3 in real program with real data. Now lets tests the dals Start by see this image I have 4-5 calls on every method, the one after the other. The results are. For a loop of 100 times, ask for 5 Rows, one not exist, approximatively.. Simple adonet:81ms SubSonic 2 :210ms linq2sql :1.70sec linq2sql using CompiledQuery.Compile :239ms Subsonic 3 :15.00sec (wow - extreme slow) The project http://www.planethost.gr/DalSpeedTests.rar Can any one confirm this benchmark, or make any optimizations to help me out ? Other tests Some one publish here this link http://ormbattle.net/ (and then remove it - don not know why) In this page you can find a really useful advanced tests for all, except subsonic 2 and subsonic 3 that I have here ! Optimizing What I really ask here is if some one can now any trick how to optimize the DALs, not by changing the test code, but by changing the code and the settings on each dal. For example... Optimizing Linq2SQL I start search how to optimize Linq2sql and found this article, and maybe more exist. Finally I make the tricks from that page to run, and optimize the code using them all. The speed was near 1.50sec from 1.70.... big improvement, but still slow. Then I found a different way - same idea article, and wow ! the speed is blow up. Using this trick with CompiledQuery.Compile, the time from 1.5sec is now 239ms. Here is the code for the precompiled... Func<DataClassesDataContext, int, IQueryable<Product>> compiledQuery = CompiledQuery.Compile((DataClassesDataContext meta, int IdToFind) => (from myData in meta.Products where myData.ProductID.Equals(IdToFind) select myData)); StringBuilder Test = new StringBuilder(); int[] MiaSeira = { 5, 6, 10, 100, 7 }; using (DataClassesDataContext context = new DataClassesDataContext()) { context.ObjectTrackingEnabled = false; for (int i = 0; i < 100; i++) { foreach (int EnaID in MiaSeira) { var oFindThat2P = compiledQuery(context, EnaID); foreach (Product One in oFindThat2P) { Test.Append("<br />"); Test.Append(One.ProductName); } } } } Optimizing SubSonic 3 and problems I make many performance profiling, and start change the one after the other and the speed is better but still too slow. I post them on subsonic group but they ignore the problem, they say that everything is fast... Here is some capture of my profiling and delay points inside subsonic source code I have end up that subsonic3 make more call on the structure of the database rather than on data itself. Needs to reconsider the hole way of asking for data, and follow the subsonic2 idea if this is possible. Try to make precompile to subsonic 3 like I did in linq2Sql but fail for the moment... Optimizing SubSonic 2 After I discover that subsonic 3 is extreme slow, I start my checks on subsonic 2 - that I have never done before believing that is fast. (and it is) So its come up with some points that can be faster. For example there are many loops like this ones that actually is slow because of string manipulation and compares inside the loop. I must say to you that this code called million of times ! on a period of few minutes ! of data asking from the program. On small amount of tables and small fields maybe this is not a big think for some people, but on large amount of tables, the delay is even more. So I decide and optimize the subsonic 2 by my self, by replacing the string compares, with number compares! Simple. I do that almost on every point that profiler say that is slow. I change also all small points that can be even a little faster, and disable some not so used thinks. The results, 5% faster on NorthWind database, near 20% faster on my database with 250 tables. That is count with 500ms less in 10 seconds process on northwind, 100ms faster on my database on 500ms process time. I do not have captures to show you for that because I have made them with different code, different time, and track them down on paper. Anyway this is my story and my question on all that, what else do you know to make them even faster... For this measures I have use Subsonic 2.2 optimized by me, Subsonic 3.0.0.3 a little optimized by me, and Dot.Net 3.5

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• Simple Grouping With TableSorter Plugin

  - by HurnsMobile

  Im playing around with the Tablesorter plug-in for jQuery and was trying to get a very simple grouping functionality added into it. Using the follow html/js works great until you click sort again and reverse the order. The headers get moved to the bottom of the group when this happens. The following is my (admitedly hacky) attempt at it. Does anyone have any ideas? <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <title>Table Manipulation Test</title> <link type="text/css" href="css/ui-lightness/jquery-ui-1.8.1.custom.css" rel="stylesheet" /> <link rel="stylesheet" href="tablesorter/themes/green/style.css" type="text/css"/> <script type="text/javascript" src="js/jquery-1.4.2.min.js"></script> <script type="text/javascript" src="js/jquery-ui-1.8.1.custom.min.js"></script> <script type="text/javascript" src="tablesorter/jquery.tablesorter.min.js"></script> <script type="text/javascript"> $(document).ready(function() { $("#test_table").tablesorter({ sortForce: [[3,0]] }); $(".group_details").hide(); $(".group_header").click(function(){ var group = $(this).attr("group"); var $expander = $(this).children("td.expanderguy") if ($("." + group + ":visible").length){ $("." + group + "").fadeOut('fast'); $expander.html("<img src='icons/plus.gif'>"); } else{ $("." + group + "").fadeIn('fast'); $expander.html("<img src='icons/minus.gif'>"); } }); } ); </script> <style type="text/css"> .group_header td{ background-color: #888888; !important } </style> </head> <body> <table id="test_table" class="tablesorter"> <thead> <tr><th>First Name</th><th>Last Name</th><th>Email</th><th>Due Date</th><th>Amount Due</th></tr> </thead> <tbody> <tr class="group_header" group="group1"><td class="expanderguy"><img src="icons/plus.gif"></td><td></td><td></td><td>Monday, June 7</td><td></td></tr> <tr class="group_details group1"><td>Flavian</td><td>Wenceslas</td><td>[email protected]</td><td>Monday, June 7</td><td>$100</td></tr> <tr class="group_details group1"><td>Gordian</td><td>Ives</td><td>[email protected]</td><td>Monday, June 7</td><td>$1700</td></tr> <tr class="group_details group1"><td>Saladin</td><td>Tarquin</td><td>[email protected]</td><td>Monday, June 7</td><td>$1700</td></tr> <tr class="group_details group1"><td>Urban</td><td>Cyprian</td><td>[email protected]</td><td>Monday, June 7</td><td>$1500</td></tr> <tr class="group_details group1"><td>Sargon</td><td>Swithun</td><td>[email protected]</td><td>Monday, June 7</td><td>$1100</td></tr> <tr class="group_details group1"><td>Pompey</td><td>Ladislas</td><td>[email protected]</td><td>Monday, June 7</td><td>$300</td></tr> <tr class="group_details group1"><td>Attila</td><td>Hiawatha</td><td>[email protected]</td><td>Monday, June 7</td><td>$200</td></tr> <tr class="group_header" group="group2"><td class="expanderguy"><img src="icons/plus.gif"></td><td></td><td></td><td>Tuesday, June 8</td><td></td></tr> <tr class="group_details group2"><td>Bruce</td><td>Fenton</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$1700</td></tr> <tr class="group_details group2"><td>Wade</td><td>Sequoia</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$1400</td></tr> <tr class="group_details group2"><td>Eddie</td><td>Jerold</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$1100</td></tr> <tr class="group_details group2"><td>Lynn</td><td>Lucan</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$1200</td></tr> <tr class="group_details group2"><td>Taegan</td><td>Tadg</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$100</td></tr> <tr class="group_details group2"><td>Clyde</td><td>Reed</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$6100</td></tr> <tr class="group_details group2"><td>Alaois</td><td>Art</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$2100</td></tr> <tr class="group_details group2"><td>Gilbert</td><td>Patsy</td><td>[email protected]</td><td>Tuesday, June 8</td><td>$1500</td></tr> <tr class="group_header" group="group3"><td class="expanderguy"><img src="icons/plus.gif"></td><td></td><td></td><td>Wednesday, June 9</td><td></td></tr> <tr class="group_details group3" ><td>Clem</td><td>Eben</td><td>[email protected]</td><td>Wednesday, June 9</td><td>$2100</td></tr> <tr class="group_details group3" ><td>Elijah</td><td>Julyan</td><td>[email protected]</td><td>Wednesday, June 9</td><td>$2100</td></tr> <tr class="group_details group3" ><td>Marvyn</td><td>Damian</td><td>[email protected]</td><td>Wednesday, June 9</td><td>$1100</td></tr> <tr class="group_details group3" ><td>Sawyer</td><td>Ryker</td><td>[email protected]</td><td>Wednesday, June 9</td><td>$500</td></tr> </tbody> </table> </body>

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• JQuery Hover li Show div which sits outside li structure

  - by Dave_Stott

  Hi everyone I'm currently trying to create a "mega" dropout menu using JQuery but have encountered an issue I'm yet to be able to resolve. At the moment I have the following HTML structure: <div id="TopNav" class="grid_16"> <ul class="cmsListMenuUL level0" id="TopNavMenu"> <li class="cmsListMenuLIcmsListMenuLI highlightedLI" id="TopNavMenu_Home"><a href="/"> <span class="text">Home</span></a></li> <li class="cmsListMenuLIfirst" id="TopNavMenu_0_1"><a href="/Key-Sectors.aspx" class="cmsListMenuLink"> <span class="text">Key Sectors</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_2"><a href="/Global-Brands.aspx" class="cmsListMenuLink"> <span class="text">Global Brands</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_3"><a href="/News---Features.aspx" class="cmsListMenuLink"> <span class="text">News &amp; Features</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_4"><a href="/Videos.aspx" class="cmsListMenuLink"> <span class="text">Videos</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_5"><a href="/Events.aspx" class="cmsListMenuLink"> <span class="text">Events</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_6"><a href="/Key-Cities.aspx" class="cmsListMenuLink"> <span class="text">Key Cities</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_7"><a href="/Doing-Business-in-Yorkshire.aspx" class="cmsListMenuLink"><span class="text">Doing Business in Yorkshire</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_8"><a href="/How-We-Can-Help.aspx" class="cmsListMenuLink"> <span class="text">How We Can Help</span></a></li> <li class="cmsListMenuLI" id="TopNavMenu_0_9"><a href="/Contact-Us.aspx" class="cmsListMenuLink"> <span class="text">Contact Us</span></a></li> </ul> </div> <div class="sectorsDropped"> <div class="floatLeft leftColumn"> <div class="parentItem" style="border-color: #0064BE;"> <a href="/Key-Sectors/Advanced-Engineering---Materials.aspx" class="parentItemContent"> Advanced Engineering &amp; Materials</a><div class="childItem"> <a href="/Key-Sectors/Advanced-Engineering---Materials/Nuclear.aspx">- Nuclear</a></div> <div class="childItem"> <a href="/Key-Sectors/Advanced-Engineering---Materials/Logistics---Infrastructure.aspx"> - Logistics &amp; Infrastructure</a></div> </div> <div class="parentItem" style="border-color: #FFB611;"> <a href="/Key-Sectors/Chemicals.aspx" class="parentItemContent">Chemicals</a></div> <div class="parentItem" style="border-color: #B7CC0B;"> <a href="/Key-Sectors/Environmental-Technologies.aspx" class="parentItemContent">Environmental Technologies</a><div class="childItem"> <a href="/Key-Sectors/Environmental-Technologies/Offshore-Wind.aspx">- Offshore Wind</a></div> <div class="childItem"> <a href="/Key-Sectors/Environmental-Technologies/Carbon-Capture---Storage.aspx">- Carbon Capture &amp; Storage</a></div> <div class="childItem"> <a href="/Key-Sectors/Environmental-Technologies/Tidal-Power.aspx">- Tidal Power</a></div> <div class="childItem"> <a href="/Key-Sectors/Environmental-Technologies/Biomass.aspx">- Biomass</a></div> </div> </div> <div class="floatLeft rightColumn"> <div class="parentItem" style="border-color: #AC26AA;"> <a href="/Key-Sectors/Digital---New-Media.aspx" class="parentItemContent">Digital &amp; New Media</a></div> <div class="parentItem" style="border-color: #e1477e;"> <a href="/Key-Sectors/Food---Drink.aspx" class="parentItemContent">Food &amp; Drink</a></div> <div class="parentItem" style="border-color: #00c5b5;"> <a href="/Key-Sectors/Healthcare-Technologies.aspx" class="parentItemContent">Healthcare Technologies</a><div class="childItem"> <a href="/Key-Sectors/Healthcare-Technologies/Biotechnology.aspx">- Biotechnology</a></div> <div class="childItem"> <a href="/Key-Sectors/Healthcare-Technologies/Pharmaceuticals.aspx">- Pharmaceuticals</a></div> <div class="childItem"> <a href="/Key-Sectors/Healthcare-Technologies/Medical-Devices.aspx">- Medical Devices</a></div> </div> <div class="parentItem" style="border-color: #AC1A2F;"> <a href="/Key-Sectors/Financial---Professional.aspx" class="parentItemContent">Financial &amp; Professional</a></div> </div> </div> In normal circumstances the div containing the "mega" menu options would sit inside the li item that fires the show/hide but this is currently not possible as the ul list of navigation links is rendered using a 3rd party piece of software which does not provide an equivalent of an OnItemDataBound event for me to be able to inject the div into the item Does anyone know of a way, using JQuery, of showing the div but maintain the display of the div as the mouse focus leaves the li that originaly displayed the div and actually enters the div? I'm currently using the following JQuery which displays the div correctly but as the mouse focus enters the div the div then disappears as the mouse focus from the li has now moved: $(document).ready(function() { function addMega(){ $(".sectorsDropped").toggle("fast"); } function removeMega(){ $(".sectorsDropped").toggle("fast"); } var megaConfig = { interval: 500, sensitivity: 4, over: addMega, timeout: 500, out: removeMega }; $("#TopNavMenu_0_1").hoverIntent(megaConfig) }); Thanks Dave

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• Why does Ubuntu 9.10 hang during boot at "Booting processor 1 APIC 0x1 ip 0x6000"?

  - by BraeburnDev

  I recently installed a new copy of Ubuntu 9.10 (Kernel 2.6.31-14) on to my Hp Pavilion dv6t, so I can setup a Linux development environment. The install went flawlessly and I proceeded with Ubuntu's udate manager's long list of updates (292 in all). I also setup a swap file and activated a Nvidia 185 driver for the Nvidia 260m GPU on the machine. After all this was done I restarted the computer and booted into Ubuntu this time with a newer 2.6.31-19 Kernel which was installed from the update manager. During booth the computer hung at this point: Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013136] Performance Counters: Nehalem/Corei7 events, Intel PMU driver. Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013141] ... version: 3 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013142] ... bit width: 48 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013144] ... generic counters: 4 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013146] ... value mask: 0000ffffffffffff Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013147] ... max period: 000000007fffffff Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013149] ... fixed-purpose counters: 3 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.013151] ... counter mask: 000000070000000f Feb 24 14:23:12 braeburn-laptop kernel: [ 0.015539] ACPI: Core revision 20090521 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.052264] Setting APIC routing to flat Feb 24 14:23:12 braeburn-laptop kernel: [ 0.052639] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.152580] CPU0: Intel(R) Core(TM) i7 CPU Q 720 @ 1.60GHz stepping 05 Feb 24 14:23:12 braeburn-laptop kernel: [ 0.270845] Booting processor 1 APIC 0x1 ip 0x6000 I can post a full kern.log of this boot process if requested. Hopefully this is enough information to go on. I should add that I'm still new to configuring and running a Linux OS although I know enough basic command line usage to do software development. This is my attempt to become more familiar with Linux and manage my own system. I'd like to get some insight on the nature of this system hang, what the problem is and how to resolve it. At this point I can scrap the install if I broke something, but my intuition says this is an issue with the kernel recognizing the correct hardware configuration for my system, or perhaps this is an issue with the APIC drivers managing Nehalem's new power management capabilities? Thanks for looking at this issue and providing feed back.

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• .Net 3.5 Asynchronous Socket Server Performance Problem

  - by iBrAaAa

  I'm developing an Asynchronous Game Server using .Net Socket Asynchronous Model( BeginAccept/EndAccept...etc.) The problem I'm facing is described like that: When I have only one client connected, the server response time is very fast but once a second client connects, the server response time increases too much. I've measured the time from a client sends a message to the server until it gets the reply in both cases. I found that the average time in case of one client is about 17ms and in case of 2 clients about 280ms!!! What I really see is that: When 2 clients are connected and only one of them is moving(i.e. requesting service from the server) it is equivalently equal to the case when only one client is connected(i.e. fast response). However, when the 2 clients move at the same time(i.e. requests service from the server at the same time) their motion becomes very slow (as if the server replies each one of them in order i.e. not simultaneously). Basically, what I am doing is that: When a client requests a permission for motion from the server and the server grants him the request, the server then broadcasts the new position of the client to all the players. So if two clients are moving in the same time, the server is eventually trying to broadcast to both clients the new position of each of them at the same time. EX: Client1 asks to go to position (2,2) Client2 asks to go to position (5,5) Server sends to each of Client1 & Client2 the same two messages: message1: "Client1 at (2,2)" message2: "Client2 at (5,5)" I believe that the problem comes from the fact that Socket class is thread safe according MSDN documentation http://msdn.microsoft.com/en-us/library/system.net.sockets.socket.aspx. (NOT SURE THAT IT IS THE PROBLEM) Below is the code for the server: /// /// This class is responsible for handling packet receiving and sending /// public class NetworkManager { /// /// An integer to hold the server port number to be used for the connections. Its default value is 5000. /// private readonly int port = 5000; /// /// hashtable contain all the clients connected to the server. /// key: player Id /// value: socket /// private readonly Hashtable connectedClients = new Hashtable(); /// /// An event to hold the thread to wait for a new client /// private readonly ManualResetEvent resetEvent = new ManualResetEvent(false); /// /// keeps track of the number of the connected clients /// private int clientCount; /// /// The socket of the server at which the clients connect /// private readonly Socket mainSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); /// /// The socket exception that informs that a client is disconnected /// private const int ClientDisconnectedErrorCode = 10054; /// /// The only instance of this class. /// private static readonly NetworkManager networkManagerInstance = new NetworkManager(); /// /// A delegate for the new client connected event. /// /// the sender object /// the event args public delegate void NewClientConnected(Object sender, SystemEventArgs e); /// /// A delegate for the position update message reception. /// /// the sender object /// the event args public delegate void PositionUpdateMessageRecieved(Object sender, PositionUpdateEventArgs e); /// /// The event which fires when a client sends a position message /// public PositionUpdateMessageRecieved PositionUpdateMessageEvent { get; set; } /// /// keeps track of the number of the connected clients /// public int ClientCount { get { return clientCount; } } /// /// A getter for this class instance. /// /// only instance. public static NetworkManager NetworkManagerInstance { get { return networkManagerInstance; } } private NetworkManager() {} /// Starts the game server and holds this thread alive /// public void StartServer() { //Bind the mainSocket to the server IP address and port mainSocket.Bind(new IPEndPoint(IPAddress.Any, port)); //The server starts to listen on the binded socket with max connection queue //1024 mainSocket.Listen(1024); //Start accepting clients asynchronously mainSocket.BeginAccept(OnClientConnected, null); //Wait until there is a client wants to connect resetEvent.WaitOne(); } /// /// Receives connections of new clients and fire the NewClientConnected event /// private void OnClientConnected(IAsyncResult asyncResult) { Interlocked.Increment(ref clientCount); ClientInfo newClient = new ClientInfo { WorkerSocket = mainSocket.EndAccept(asyncResult), PlayerId = clientCount }; //Add the new client to the hashtable and increment the number of clients connectedClients.Add(newClient.PlayerId, newClient); //fire the new client event informing that a new client is connected to the server if (NewClientEvent != null) { NewClientEvent(this, System.EventArgs.Empty); } newClient.WorkerSocket.BeginReceive(newClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), newClient); //Start accepting clients asynchronously again mainSocket.BeginAccept(OnClientConnected, null); } /// Waits for the upcoming messages from different clients and fires the proper event according to the packet type. /// /// private void WaitForData(IAsyncResult asyncResult) { ClientInfo sendingClient = null; try { //Take the client information from the asynchronous result resulting from the BeginReceive sendingClient = asyncResult.AsyncState as ClientInfo; // If client is disconnected, then throw a socket exception // with the correct error code. if (!IsConnected(sendingClient.WorkerSocket)) { throw new SocketException(ClientDisconnectedErrorCode); } //End the pending receive request sendingClient.WorkerSocket.EndReceive(asyncResult); //Fire the appropriate event FireMessageTypeEvent(sendingClient.ConvertBytesToPacket() as BasePacket); // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } catch (SocketException e) { if (e.ErrorCode == ClientDisconnectedErrorCode) { // Close the socket. if (sendingClient.WorkerSocket != null) { sendingClient.WorkerSocket.Close(); sendingClient.WorkerSocket = null; } // Remove it from the hash table. connectedClients.Remove(sendingClient.PlayerId); if (ClientDisconnectedEvent != null) { ClientDisconnectedEvent(this, new ClientDisconnectedEventArgs(sendingClient.PlayerId)); } } } catch (Exception e) { // Begin receiving data from this client sendingClient.WorkerSocket.BeginReceive(sendingClient.Buffer, 0, BasePacket.GetMaxPacketSize(), SocketFlags.None, new AsyncCallback(WaitForData), sendingClient); } } /// /// Broadcasts the input message to all the connected clients /// /// public void BroadcastMessage(BasePacket message) { byte[] bytes = message.ConvertToBytes(); foreach (ClientInfo client in connectedClients.Values) { client.WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, client); } } /// /// Sends the input message to the client specified by his ID. /// /// /// The message to be sent. /// The id of the client to receive the message. public void SendToClient(BasePacket message, int id) { byte[] bytes = message.ConvertToBytes(); (connectedClients[id] as ClientInfo).WorkerSocket.BeginSend(bytes, 0, bytes.Length, SocketFlags.None, SendAsync, connectedClients[id]); } private void SendAsync(IAsyncResult asyncResult) { ClientInfo currentClient = (ClientInfo)asyncResult.AsyncState; currentClient.WorkerSocket.EndSend(asyncResult); } /// Fires the event depending on the type of received packet /// /// The received packet. void FireMessageTypeEvent(BasePacket packet) { switch (packet.MessageType) { case MessageType.PositionUpdateMessage: if (PositionUpdateMessageEvent != null) { PositionUpdateMessageEvent(this, new PositionUpdateEventArgs(packet as PositionUpdatePacket)); } break; } } } The events fired are handled in a different class, here are the event handling code for the PositionUpdateMessage (Other handlers are irrelevant): private readonly Hashtable onlinePlayers = new Hashtable(); /// /// Constructor that creates a new instance of the GameController class. /// private GameController() { //Start the server server = new Thread(networkManager.StartServer); server.Start(); //Create an event handler for the NewClientEvent of networkManager networkManager.PositionUpdateMessageEvent += OnPositionUpdateMessageReceived; } /// /// this event handler is called when a client asks for movement. /// private void OnPositionUpdateMessageReceived(object sender, PositionUpdateEventArgs e) { Point currentLocation = ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position; Point locationRequested = e.PositionUpdatePacket.Position; ((PlayerData)onlinePlayers[e.PositionUpdatePacket.PlayerId]).Position = locationRequested; // Broadcast the new position networkManager.BroadcastMessage(new PositionUpdatePacket { Position = locationRequested, PlayerId = e.PositionUpdatePacket.PlayerId }); }

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• Numpy zero rank array indexing/broadcasting

  - by Lemming

  I'm trying to write a function that supports broadcasting and is fast at the same time. However, numpy's zero-rank arrays are causing trouble as usual. I couldn't find anything useful on google, or by searching here. So, I'm asking you. How should I implement broadcasting efficiently and handle zero-rank arrays at the same time? This whole post became larger than anticipated, sorry. Details: To clarify what I'm talking about I'll give a simple example: Say I want to implement a Heaviside step-function. I.e. a function that acts on the real axis, which is 0 on the negative side, 1 on the positive side, and from case to case either 0, 0.5, or 1 at the point 0. Implementation Masking The most efficient way I found so far is the following. It uses boolean arrays as masks to assign the correct values to the corresponding slots in the output vector. from numpy import * def step_mask(x, limit=+1): """Heaviside step-function. y = 0 if x < 0 y = 1 if x > 0 See below for x == 0. Arguments: x Evaluate the function at these points. limit Which limit at x == 0? limit > 0: y = 1 limit == 0: y = 0.5 limit < 0: y = 0 Return: The values corresponding to x. """ b = broadcast(x, limit) out = zeros(b.shape) out[x>0] = 1 mask = (limit > 0) & (x == 0) out[mask] = 1 mask = (limit == 0) & (x == 0) out[mask] = 0.5 mask = (limit < 0) & (x == 0) out[mask] = 0 return out List Comprehension The following-the-numpy-docs way is to use a list comprehension on the flat iterator of the broadcast object. However, list comprehensions become absolutely unreadable for such complicated functions. def step_comprehension(x, limit=+1): b = broadcast(x, limit) out = empty(b.shape) out.flat = [ ( 1 if x_ > 0 else ( 0 if x_ < 0 else ( 1 if l_ > 0 else ( 0.5 if l_ ==0 else ( 0 ))))) for x_, l_ in b ] return out For Loop And finally, the most naive way is a for loop. It's probably the most readable option. However, Python for-loops are anything but fast. And hence, a really bad idea in numerics. def step_for(x, limit=+1): b = broadcast(x, limit) out = empty(b.shape) for i, (x_, l_) in enumerate(b): if x_ > 0: out[i] = 1 elif x_ < 0: out[i] = 0 elif l_ > 0: out[i] = 1 elif l_ < 0: out[i] = 0 else: out[i] = 0.5 return out Test First of all a brief test to see if the output is correct. >>> x = array([-1, -0.1, 0, 0.1, 1]) >>> step_mask(x, +1) array([ 0., 0., 1., 1., 1.]) >>> step_mask(x, 0) array([ 0. , 0. , 0.5, 1. , 1. ]) >>> step_mask(x, -1) array([ 0., 0., 0., 1., 1.]) It is correct, and the other two functions give the same output. Performance How about efficiency? These are the timings: In [45]: xl = linspace(-2, 2, 500001) In [46]: %timeit step_mask(xl) 10 loops, best of 3: 19.5 ms per loop In [47]: %timeit step_comprehension(xl) 1 loops, best of 3: 1.17 s per loop In [48]: %timeit step_for(xl) 1 loops, best of 3: 1.15 s per loop The masked version performs best as expected. However, I'm surprised that the comprehension is on the same level as the for loop. Zero Rank Arrays But, 0-rank arrays pose a problem. Sometimes you want to use a function scalar input. And preferably not have to worry about wrapping all scalars in at least 1-D arrays. >>> step_mask(1) Traceback (most recent call last): File "<ipython-input-50-91c06aa4487b>", line 1, in <module> step_mask(1) File "script.py", line 22, in step_mask out[x>0] = 1 IndexError: 0-d arrays can't be indexed. >>> step_for(1) Traceback (most recent call last): File "<ipython-input-51-4e0de4fcb197>", line 1, in <module> step_for(1) File "script.py", line 55, in step_for out[i] = 1 IndexError: 0-d arrays can't be indexed. >>> step_comprehension(1) array(1.0) Only the list comprehension can handle 0-rank arrays. The other two versions would need special case handling for 0-rank arrays. Numpy gets a bit messy when you want to use the same code for arrays and scalars. However, I really like to have functions that work on as arbitrary input as possible. Who knows which parameters I'll want to iterate over at some point. Question: What is the best way to implement a function as the one above? Is there a way to avoid if scalar then like special cases? I'm not looking for a built-in Heaviside. It's just a simplified example. In my code the above pattern appears in many places to make parameter iteration as simple as possible without littering the client code with for loops or comprehensions. Furthermore, I'm aware of Cython, or weave & Co., or implementation directly in C. However, the performance of the masked version above is sufficient for the moment. And for the moment I would like to keep things as simple as possible.

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