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• Scalable Database Tagging Schema

  - by Longpoke

  EDIT: To people building tagging systems. Don't read this. It is not what you are looking for. I asked this when I wasn't aware that RDBMS all have their own optimization methods, just use a simple many to many scheme. I have a posting system that has millions of posts. Each post can have an infinite number of tags associated with it. Users can create tags which have notes, date created, owner, etc. A tag is almost like a post itself, because people can post notes about the tag. Each tag association has an owner and date, so we can see who added the tag and when. My question is how can I implement this? It has to be fast searching posts by tag, or tags by post. Also, users can add tags to posts by typing the name into a field, kind of like the google search bar, it has to fill in the rest of the tag name for you. I have 3 solutions at the moment, but not sure which is the best, or if there is a better way. Note that I'm not showing the layout of notes since it will be trivial once I get a proper solution for tags. Method 1. Linked list tagId in post points to a linked list in tag_assoc, the application must traverse the list until flink=0 post: id, content, ownerId, date, tagId, notesId tag_assoc: id, tagId, ownerId, flink tag: id, name, notesId Method 2. Denormalization tags is simply a VARCHAR or TEXT field containing a tab delimited array of tagId:ownerId. It cannot be a fixed size. post: id, content, ownerId, date, tags, notesId tag: id, name, notesId Method 3. Toxi (from: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html, also same thing here: http://stackoverflow.com/questions/20856/how-do-you-recommend-implementing-tags-or-tagging) post: id, content, ownerId, date, notesId tag_assoc: ownerId, tagId, postId tag: id, name, notesId Method 3 raises the question, how fast will it be to iterate through every single row in tag_assoc? Methods 1 and 2 should be fast for returning tags by post, but for posts by tag, another lookup table must be made. The last thing I have to worry about is optimizing searching tags by name, I have not worked that out yet. I made an ASCII diagram here: http://pastebin.com/f1c4e0e53

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• How to draw a filled envelop like a cone on OpenGL (using GLUT)?

  - by ashishsony

  Hi, I am relatively new to OpenGL programming...currently involved in a project that uses freeglut for opengl rendering... I need to draw an envelop looking like a cone (2D) that has to be filled with some color and some transparency applied. Is the freeglut toolkit equipped with such an inbuilt functionality to draw filled geometries(or some trick)?? or is there some other api that has an inbuilt support for filled up geometries.. Thanks. Best Regards. Edit1: just to clarify the 2D cone thing... the envelop is the graphical interpretation of the coverage area of an aircraft during interception(of an enemy aircraft)...that resembles a sector of a circle..i should have mentioned sector instead.. and glutSolidCone doesnot help me as i want to draw a filled sector of a circle...which i have already done...what remains to do is to fill it with some color... how to fill geometries with color in opengl?? Thanks. Edit2: Ok thanks for replying...all the answers posted to this questions can work for my problem in a way.. But i would definitely would want to know a way how to fill a geometry with some color. Say if i want to draw an envelop which is a parabola...in that case there would be no default glut function to actually draw a filled parabola(or is there any??).. So to generalise this question...how to draw a custom geometry in some solid color?? Thanks. Edit3: The answer that mstrobl posted works for GL_TRIANGLES but for such a code: glBegin(GL_LINE_STRIP); glColor3f(0.0, 0.0, 1.0); glVertex3f(0.0, 0.0, 0.0); glColor3f(0.0, 0.0, 1.0); glVertex3f(200.0, 0.0, 0.0); glColor3f(0.0, 0.0, 1.0); glVertex3f(200.0, 200.0, 0.0); glColor3f(0.0, 0.0, 1.0); glVertex3f(0.0, 200.0, 0.0); glColor3f(0.0, 0.0, 1.0); glVertex3f(0.0, 0.0, 0.0); glEnd(); which draws a square...only a wired square is drawn...i need to fill it with blue color. anyway to do it? if i put some drawing commands for a closed curve..like a pie..and i need to fill it with a color is there a way to make it possible... i dont know how its possible for GL_TRIANGLES... but how to do it for any closed curve?? Thanks.

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• How to cache queries in EJB and return result efficient (performance POV)

  - by Maxym

  I use JBoss EJB 3.0 implementation (JBoss 4.2.3 server) At the beginning I created native query all the time using construction like Query query = entityManager.createNativeQuery("select * from _table_"); Of couse it is not that efficient, I performed some tests and found out that it really takes a lot of time... Then I found a better way to deal with it, to use annotation to define native queries: @NamedNativeQuery( name = "fetchData", value = "select * from _table_", resultClass=Entity.class ) and then just use it Query query = entityManager.createNamedQuery("fetchData"); the performance of code line above is two times better than where I started from, but still not that good as I expected... then I found that I can switch to Hibernate annotation for NamedNativeQuery (anyway, JBoss's implementation of EJB is based on Hibernate), and add one more thing: @NamedNativeQuery( name = "fetchData2", value = "select * from _table_", resultClass=Entity.class, readOnly=true) readOnly - marks whether the results are fetched in read-only mode or not. It sounds good, because at least in this case of mine I don't need to update data, I wanna just fetch it for report. When I started server to measure performance I noticed that query without readOnly=true (by default it is false) returns result with each iteration better and better, and at the same time another one (fetchData2) works like "stable" and with time difference between them is shorter and shorter, and after 5 iterations speed of both was almost the same... The questions are: 1) is there any other way to speed query using up? Seems that named queries should be prepared once, but I can't say it... In fact if to create query once and then just use it it would be better from performance point of view, but it is problematic to cache this object, because after creating query I can set parameters (when I use ":variable" in query), and it changes query object (isn't it?). well, is here any way to cache them? Or named query is the best option I can use? 2) any other approaches how to make results retrieveng faster. I mean, for instance I don't need those Entities to be attached, I won't update them, all I need is just fetch collection of data. Maybe readOnly is the only available way, so I can't speed it up, but who knows :) P.S. I don't ask about DB performance, all I need now is how not to create query all the time, so use it efficient, and to "allow" EJB to do less job with the same result concerning data returning.

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• Click on notification starts activity twice

  - by Karussell

  I'm creating a notification from a service with the following code: NotificationManager notificationManager = (NotificationManager) ctx .getSystemService(Context.NOTIFICATION_SERVICE); CharSequence tickerText = "bla ..."; long when = System.currentTimeMillis(); Notification notification = new Notification(R.drawable.icon, tickerText, when); Intent notificationIntent = new Intent(ctx, SearchActivity.class). putExtra(SearchActivity.INTENT_SOURCE, MyNotificationService.class.getSimpleName()); PendingIntent contentIntent = PendingIntent.getActivity(ctx, 0, notificationIntent, 0); notification.setLatestEventInfo(ctx, ctx.getString(R.string.app_name), tickerText, contentIntent); notification.flags |= Notification.FLAG_AUTO_CANCEL; notificationManager.notify(1, notification); The logs clearly says that the the method startActivity is called twice times: 04-02 23:48:06.923: INFO/ActivityManager(2466): Starting activity: Intent { act=android.intent.action.SEARCH cmp=com.xy/.SearchActivity bnds=[0,520][480,616] (has extras) } 04-02 23:48:06.923: WARN/ActivityManager(2466): startActivity called from non-Activity context; forcing Intent.FLAG_ACTIVITY_NEW_TASK for: Intent { act=android.intent.action.SEARCH cmp=com.xy/.SearchActivity bnds=[0,520][480,616] (has extras) } 04-02 23:48:06.958: INFO/ActivityManager(2466): Starting activity: Intent { act=android.intent.action.SEARCH cmp=com.xy/.SearchActivity bnds=[0,0][480,96] (has extras) } 04-02 23:48:06.958: WARN/ActivityManager(2466): startActivity called from non-Activity context; forcing Intent.FLAG_ACTIVITY_NEW_TASK for: Intent { act=android.intent.action.SEARCH cmp=com.xy/.SearchActivity bnds=[0,0][480,96] (has extras) } 04-02 23:48:07.087: INFO/notification(5028): onStartCmd: received start id 2: Intent { cmp=com.xy/.NotificationService } 04-02 23:48:07.310: INFO/notification(5028): onStartCmd: received start id 3: Intent { cmp=com.xy/.NotificationService } 04-02 23:48:07.392: INFO/ActivityManager(2466): Displayed activity com.xy/.SearchActivity: 462 ms (total 462 ms) 04-02 23:48:07.392: INFO/ActivityManager(2466): Displayed activity com.xy/.SearchActivity: 318 ms (total 318 ms) Why are they started twice? There are two identical questions on stackoverflow: here and here. But they do not explain what the initial issue could be and they do not work for me. E.g. changing to launchMode singleTop is not appropriated for me and it should work without changing launchMode according to the official docs (see Invoking the search dialog). Nevertheless I also tried to add the following flags to notificationIntent Intent.FLAG_ACTIVITY_CLEAR_TOP | PendingIntent.FLAG_UPDATE_CURRENT but the problem remains the same.

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• What's the C strategy to "imitate" a C++ template ?

  - by Andrei Ciobanu

  After reading some examples on stackoverflow, and following some of the answers for my previous questions (1), I've eventually come with a "strategy" for this. I've come to this: 1) Have a declare section in the .h file. Here I will define the data-structure, and the accesing interface. Eg.: /** * LIST DECLARATION. (DOUBLE LINKED LIST) */ #define NM_TEMPLATE_DECLARE_LIST(type) \ typedef struct nm_list_elem_##type##_s { \ type data; \ struct nm_list_elem_##type##_s *next; \ struct nm_list_elem_##type##_s *prev; \ } nm_list_elem_##type ; \ typedef struct nm_list_##type##_s { \ unsigned int size; \ nm_list_elem_##type *head; \ nm_list_elem_##type *tail; \ int (*cmp)(const type e1, const type e2); \ } nm_list_##type ; \ \ nm_list_##type *nm_list_new_##type##_(int (*cmp)(const type e1, \ const type e2)); \ \ (...other functions ...) 2) Wrap the functions in the interface inside MACROS: /** * LIST INTERFACE */ #define nm_list(type) \ nm_list_##type #define nm_list_elem(type) \ nm_list_elem_##type #define nm_list_new(type,cmp) \ nm_list_new_##type##_(cmp) #define nm_list_delete(type, list, dst) \ nm_list_delete_##type##_(list, dst) #define nm_list_ins_next(type,list, elem, data) \ nm_list_ins_next_##type##_(list, elem, data) (...others...) 3) Implement the functions: /** * LIST FUNCTION DEFINITIONS */ #define NM_TEMPLATE_DEFINE_LIST(type) \ nm_list_##type *nm_list_new_##type##_(int (*cmp)(const type e1, \ const type e2)) \ {\ nm_list_##type *list = NULL; \ list = nm_alloc(sizeof(*list)); \ list->size = 0; \ list->head = NULL; \ list->tail = NULL; \ list->cmp = cmp; \ }\ void nm_list_delete_##type##_(nm_list_##type *list, \ void (*destructor)(nm_list_elem_##type elem)) \ { \ type data; \ while(nm_list_size(list)){ \ data = nm_list_rem_##type(list, tail); \ if(destructor){ \ destructor(data); \ } \ } \ nm_free(list); \ } \ (...others...) In order to use those constructs, I have to create two files (let's call them templates.c and templates.h) . In templates.h I will have to NM_TEMPLATE_DECLARE_LIST(int), NM_TEMPLATE_DECLARE_LIST(double) , while in templates.c I will need to NM_TEMPLATE_DEFINE_LIST(int) , NM_TEMPLATE_DEFINE_LIST(double) , in order to have the code behind a list of ints, doubles and so on, generated. By following this strategy I will have to keep all my "template" declarations in two files, and in the same time, I will need to include templates.h whenever I need the data structures. It's a very "centralized" solution. Do you know other strategy in order to "imitate" (at some point) templates in C++ ? Do you know a way to improve this strategy, in order to keep things in more decentralized manner, so that I won't need the two files: templates.c and templates.h ?

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• How to count the length (number of lines) of a csv file in Rails?

  - by Mathias

  Hello, I have a form (Rails) which allows me to load a .csv file using the file_field. In the view: <% form_for(:upcsv, :html => {:multipart => true}) do |f| %> <table> <tr> <td><%= f.label("File:") %></td> <td><%= f.file_field(:filename) %></td> </tr> </table> <%= f.submit("Submit") %> <% end %> Clicking Submit redirects me to another page (create.html.erb). The file was loaded fine, and I was able to read the contents just fine in this second page. I am trying to show the number of lines in the .csv file in this second page. My controller (semi-pseudocode): class UpcsvController < ApplicationController def index end def create file = params[:upcsv][:filename] ... #params[:upcsv][:file_length] = file.length # Show number of lines in the file #params[:upcsv][:file_length] = file.size ... end end Both file.length and file.size returns '91' when my file only contains 7 lines. From the Rails documentation that I read, once the Submit button is clicked, Rails creates a temp file of the uploaded file, and the params[:upcsv][:filename] contains the contents of the temp/uploaded file and not the path to the file. And I don't know how to extract the number of lines in my original file. What is the correct way to get the number of lines in the file? My create.html.erb: <table> <tr> <td>File length:</td> <td><%= params[:upcsv][:file_length] %></td> </tr> </table> I'm really new at Rails (just started last week), so please bear with my stupid questions. Thank you!

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• Any thoughts on how to create a true 'punch-out' area in a Sprite?

  - by rhtx

  I've been working on this for awhile, now. You might also call it a 'reverse mask', or an 'inverse mask'. Basically, I'm creating a view window within a display object. I need to allow objects on the stage that are under the window to be able to interact with the mouse. This is similar to a WPF question: http://stackoverflow.com/questions/740994/use-wpf-object-to-punch-hole-in-another, which has a much shorter write-up. I've got a Class called PunchOutShield, which creates a Sprite that covers the stage (or over some desired area). The Sprite's Graphics object is filled using the color and transparency of Flex's modal screen. The result is a screen that looks like the screen which appears behind a modal PopUp. PunchOutShield has a method called punch, which takes two arguments - the first is a Shape object, which defines the shape of the punch-through area; the second is a Point object, which indicates where to position the punch-through area. It took some experimenting, but I found that I can successfully create a punch-out area (i.e. - the modal screen does not display within the bounds of the given Shape). To do this, I set cacheAsBitmap to true on the Sprite that is used to create the modal screen, and also on the Shape object, which is added to the modal screen Sprite's displayList. If I set the blend mode of the Shape to ERASE, a completely transparent area is created in the modal screen. So far, great. The problem is that Shape does not subclass InteractiveObject, so there is no way to set mouseEnabled = false on it. And so, it prevents interaction between the mouse and any objects that are visible through the punch-out area. On top of that, InteractiveObject isn't available to look at, so I can't see if there is a way to borrow what it's doing to provide the mouseEnabled functionality and apply it to a subclass of Shape. I've tried using another Sprite object, rather than a Shape object, but the blending doesn't work out correctly. I'm not sure why there is a difference, but the Shape object seems to somehow combine with the parenting Sprite, allowing the ERASE blendMode to effect the desired punch-out visual appearance. It wouldn't be the end of the world if I had to draw up the screen with a series of rectangles so that the punch-out area was just simply not drawn, but that approach won't work if the punch-out area is complex. Or round. Any thoughts on this approach, or on an alternative approach?

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• java instanceof not finding method

  - by Razvan N

  I have a problem with java instanceof. I have a class called Employee and several others that extend this one, for example - Manager. I also created another class,EmployeeStockPlan, where I wanted to test if instanceof is finding which object I am using. But when I am calling a method from the new class, I have this error: The method grantStock(Manager) is undefined for the type Loader. Sorry, I am somehow new to some thing in java, I hope I am not asking dumb questions. The Employee class: package com.example.domain; public class Employee { private int empId; private String name; private String ssn; private double salary; public Employee(int empId, String name, String ssn, double salary) { // constructor // method; this.empId = empId; this.name = name; this.ssn = ssn; this.salary = salary; } public void setName(String newName) { if (newName != null) { this.name = newName; } } public void raiseSalary(double increase) { this.salary += increase; } public String getName() { return name; } public double getSalary() { return salary; } public String getDetails() { return "Employee id: " + empId + "\n" + "Employee name: " + name; } } The Manager class: package com.example.domain; public class Manager extends Employee { private String deptName; public Manager(int empId, String name, String ssn, double salary, String dept) { super(empId, name, ssn, salary); this.deptName = dept; } public String getDeptName() { return deptName; } public String getDetails() { return super.getDetails() + "\n" + "Department: " + deptName; } } The EmployeeStockPlan class: package com.example.domain; public class EmployeeStockPlan { public void grantStock(Employee e) { // nothing calculated, just simulating; System.out.println("This is an employee!"); if (e instanceof Manager) { // process Manager stock grant System.out.println("This is a manager!"); } else { // error - instance of Engineer? System.out.println("Not an engineer!"); } return; } } The main class: EmployeeStockPlan esp = new EmployeeStockPlan(); Manager m = new Manager (12421, "Manager1", "111-4254-521", 2430, "Marketing1"); grantStock(m);

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• Can I avoid a threaded UDP socket in Python dropping data?

  - by 666craig

  First off, I'm new to Python and learning on the job, so be gentle! I'm trying to write a threaded Python app for Windows that reads data from a UDP socket (thread-1), writes it to file (thread-2), and displays the live data (thread-3) to a widget (gtk.Image using a gtk.gdk.pixbuf). I'm using queues for communicating data between threads. My problem is that if I start only threads 1 and 3 (so skip the file writing for now), it seems that I lose some data after the first few samples. After this drop it looks fine. Even by letting thread 1 complete before running thread 3, this apparent drop is still there. Apologies for the length of code snippet (I've removed the thread that writes to file), but I felt removing code would just prompt questions. Hope someone can shed some light :-) import socket import threading import Queue import numpy import gtk gtk.gdk.threads_init() import gtk.glade import pygtk class readFromUDPSocket(threading.Thread): def __init__(self, socketUDP, readDataQueue, packetSize, numScans): threading.Thread.__init__(self) self.socketUDP = socketUDP self.readDataQueue = readDataQueue self.packetSize = packetSize self.numScans = numScans def run(self): for scan in range(1, self.numScans + 1): buffer = self.socketUDP.recv(self.packetSize) self.readDataQueue.put(buffer) self.socketUDP.close() print 'myServer finished!' class displayWithGTK(threading.Thread): def __init__(self, displayDataQueue, image, viewArea): threading.Thread.__init__(self) self.displayDataQueue = displayDataQueue self.image = image self.viewWidth = viewArea[0] self.viewHeight = viewArea[1] self.displayData = numpy.zeros((self.viewHeight, self.viewWidth, 3), dtype=numpy.uint16) def run(self): scan = 0 try: while True: if not scan % self.viewWidth: scan = 0 buffer = self.displayDataQueue.get(timeout=0.1) self.displayData[:, scan, 0] = numpy.fromstring(buffer, dtype=numpy.uint16) self.displayData[:, scan, 1] = numpy.fromstring(buffer, dtype=numpy.uint16) self.displayData[:, scan, 2] = numpy.fromstring(buffer, dtype=numpy.uint16) gtk.gdk.threads_enter() self.myPixbuf = gtk.gdk.pixbuf_new_from_data(self.displayData.tostring(), gtk.gdk.COLORSPACE_RGB, False, 8, self.viewWidth, self.viewHeight, self.viewWidth * 3) self.image.set_from_pixbuf(self.myPixbuf) self.image.show() gtk.gdk.threads_leave() scan += 1 except Queue.Empty: print 'myDisplay finished!' pass def quitGUI(obj): print 'Currently active threads: %s' % threading.enumerate() gtk.main_quit() if __name__ == '__main__': # Create socket (IPv4 protocol, datagram (UDP)) and bind to address socketUDP = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) host = '192.168.1.5' port = 1024 socketUDP.bind((host, port)) # Data parameters samplesPerScan = 256 packetsPerSecond = 1200 packetSize = 512 duration = 1 # For now, set a fixed duration to log data numScans = int(packetsPerSecond * duration) # Create array to store data data = numpy.zeros((samplesPerScan, numScans), dtype=numpy.uint16) # Create queue for displaying from readDataQueue = Queue.Queue(numScans) # Build GUI from Glade XML file builder = gtk.Builder() builder.add_from_file('GroundVue.glade') window = builder.get_object('mainwindow') window.connect('destroy', quitGUI) view = builder.get_object('viewport') image = gtk.Image() view.add(image) viewArea = (1200, samplesPerScan) # Instantiate & start threads myServer = readFromUDPSocket(socketUDP, readDataQueue, packetSize, numScans) myDisplay = displayWithGTK(readDataQueue, image, viewArea) myServer.start() myDisplay.start() gtk.gdk.threads_enter() gtk.main() gtk.gdk.threads_leave() print 'gtk.main finished!'

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• How do I create a thread-safe write-once read-many value in Java?

  - by Software Monkey

  This is a problem I encounter frequently in working with more complex systems and which I have never figured out a good way to solve. It usually involves variations on the theme of a shared object whose construction and initialization are necessarily two distinct steps. This is generally because of architectural requirements, similar to applets, so answers that suggest I consolidate construction and initialization are not useful. By way of example, let's say I have a class that is structured to fit into an application framework like so: public class MyClass { private /*ideally-final*/ SomeObject someObject; MyClass() { someObject=null; } public void startup() { someObject=new SomeObject(...arguments from environment which are not available until startup is called...); } public void shutdown() { someObject=null; // this is not necessary, I am just expressing the intended scope of someObject explicitly } } I can't make someObject final since it can't be set until startup() is invoked. But I would really like it to reflect it's write-once semantics and be able to directly access it from multiple threads, preferably avoiding synchronization. The idea being to express and enforce a degree of finalness, I conjecture that I could create a generic container, like so: public class WoRmObject<T> { private T object; WoRmObject() { object=null; } public WoRmObject set(T val) { object=val; return this; } public T get() { return object; } } and then in MyClass, above, do: private final WoRmObject<SomeObject> someObject; MyClass() { someObject=new WoRmObject<SomeObject>(); } public void startup() { someObject.set(SomeObject(...arguments from environment which are not available until startup is called...)); } Which raises some questions for me: Is there a better way, or existing Java object (would have to be available in Java 4)? Is this thread-safe provided that no other thread accesses someObject.get() until after it's set() has been called. The other threads will only invoke methods on MyClass between startup() and shutdown() - the framework guarantees this. Given the completely unsynchronized WoRmObject container, it is ever possible under either JMM to see a value of object which is neither null nor a reference to a SomeObject? In other words, does has the JMM always guaranteed that no thread can observe the memory of an object to be whatever values happened to be on the heap when the object was allocated.

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• Correct usage of socket_select().

  - by Mark Tomlin

  What is the correct way to use socket_select within PHP to send and receive data? I have a connection to the server that allows for both TCP & UDP packet connections, I am utilizing both. Within these connections I'm both sending and receiving packets on the same port, but the TCP packet will be sent on one port (29999) and UDP will be sent on another port (30000). The transmission type will be that of AF_INET. The IP address will be loopback 127.0.0.1. I have many questions on how to create a socket connection within this scenario. For example, is it better to use socket_create_pair to make the connection, or use just socket_create followed by socket_connect, and then implement socket_select? There is a chance that no data will be sent from the server to the client, and it is up to the client to maintain the connection. This will be done by utilizing the time out function within the socket_select call. Should no data be sent within the time limit, the socket_select function will break and a keep alive packet can then be sent. The following script is of the client. // Create $TCP = socket_create(AF_INET, SOCK_STREAM, SOL_TCP); $UDP = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP); // Misc $isAlive = TRUE; $UDPPort = 30000; define('ISP_ISI', 1); // Connect socket_connect($TCP, '127.0.0.1', 29999); socket_connect($UDP, '127.0.0.1', $UDPPort); // Construct Parameters $recv = array($TCP, $UDP); $null = NULL; // Make The Packet to Send. $packet = pack('CCCxSSxCSa16a16', 44, ISP_ISI, 1, $UDPPort, 0, '!', 0, 'AdminPass', 'SocketSelect'); // Send ISI (InSim Init) Packet socket_write($TCP, $packet); /* Main Program Loop */ while ($isAlive == TRUE) { // Socket Select $sock = socket_select($recv, $null, $null, 5); // Check Status if ($sock === FALSE) $isAlive = FALSE; # Error else if ($sock > 0) # How does one check to find what socket changed? else # Something else happed, don't know what as it's not in the documentation, Could this be our timeout getting tripped? }

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• GHC.Generics and Type Families

  - by jberryman

  This is a question related to my module here, and is simplified a bit. It's also related to this previous question, in which I oversimplified my problem and didn't get the answer I was looking for. I hope this isn't too specific, and please change the title if you can think if a better one. Background My module uses a concurrent chan, split into a read side and write side. I use a special class with an associated type synonym to support polymorphic channel "joins": {-# LANGUAGE TypeFamilies #-} class Sources s where type Joined s newJoinedChan :: IO (s, Messages (Joined s)) -- NOT EXPORTED --output and input sides of channel: data Messages a -- NOT EXPORTED data Mailbox a instance Sources (Mailbox a) where type Joined (Mailbox a) = a newJoinedChan = undefined instance (Sources a, Sources b)=> Sources (a,b) where type Joined (a,b) = (Joined a, Joined b) newJoinedChan = undefined -- and so on for tuples of 3,4,5... The code above allows us to do this kind of thing: example = do (mb , msgsA) <- newJoinedChan ((mb1, mb2), msgsB) <- newJoinedChan --say that: msgsA, msgsB :: Messages (Int,Int) --and: mb :: Mailbox (Int,Int) -- mb1,mb2 :: Mailbox Int We have a recursive action called a Behavior that we can run on the messages we pull out of the "read" end of the channel: newtype Behavior a = Behavior (a -> IO (Behavior a)) runBehaviorOn :: Behavior a -> Messages a -> IO () -- NOT EXPORTED This would allow us to run a Behavior (Int,Int) on either of msgsA or msgsB, where in the second case both Ints in the tuple it receives actually came through separate Mailboxes. This is all tied together for the user in the exposed spawn function spawn :: (Sources s) => Behavior (Joined s) -> IO s ...which calls newJoinedChan and runBehaviorOn, and returns the input Sources. What I'd like to do I'd like users to be able to create a Behavior of arbitrary product type (not just tuples) , so for instance we could run a Behavior (Pair Int Int) on the example Messages above. I'd like to do this with GHC.Generics while still having a polymorphic Sources, but can't manage to make it work. spawn :: (Sources s, Generic (Joined s), Rep (Joined s) ~ ??) => Behavior (Joined s) -> IO s The parts of the above example that are actually exposed in the API are the fst of the newJoinedChan action, and Behaviors, so an acceptable solution can modify one or all of runBehaviorOn or the snd of newJoinedChan. I'll also be extending the API above to support sums (not implemented yet) like Behavior (Either a b) so I hoped GHC.Generics would work for me. Questions Is there a way I can extend the API above to support arbitrary Generic a=> Behavior a? If not using GHC's Generics, are there other ways I can get the API I want with minimal end-user pain (i.e. they just have to add a deriving clause to their type)?

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• WPF: Improving Performance for Running on Older PCs

  - by Phil Sandler

  So, I'm building a WPF app and did a test deployment today, and found that it performed pretty poorly. I was surprised, as we are really not doing much in the way of visual effects or animations. I deployed on two machines: the fastest and the slowest that will need to run the application (the slowest PC has an Intel Celeron 1.80GHz with 2GB RAM). The application ran pretty well on the faster machine, but was choppy on the slower machine. And when I say "choppy", I mean the cursor jumped even just passing it over any open window of the app that had focus. I opened the Task Manager Performance window, and could see that the CPU usage jumped whenever the app had focus and the cursor was moving over it. If I gave focus to another (e.g. Excel), the CPU usage went back down after a second. This happened on both machines, but the choppiness was only noticeable on the slower machine. I had very limited time to tinker on the deployment machines, so didn't do a lot of detailed testing. The app runs fine on my development machine, but I also see the CPU spiking up to 10% there, just running the cursor over the window. I downloaded the WPF performance tool from MS and have been tinkering with it (on my dev machine). The docs say this about the "Frame Rate" metric in the Perforator tool: For applications without animation, this value should be near 0. The app is not doing any heavy animation, but the frame rate stays near 50 when the cursor is over any window. The screens I tested on have column headers in a grid that "highlight" and buttons that change color and appearance when scrolled over. Even moving the mouse on blank areas of the windows cause the same Frame rate and CPU usage (doesn't seem to be related to these minor animations). (Also, I am unable to figure out how to get anything but the two default tools--Perforator and Visual Profiler--installed into the WPF performance tool. That is probably a separate question). I also have Redgate's profiling tool, but I'm not sure if that can shed any light on rendering performance. So, I realize this is not an easy thing to troubleshoot without specifics or sample code (which I can't post). My questions are: What are some general things to look for (or avoid) in the code to improve performance? What steps can I take using the WPF performance tool to narrow down the problem? Is the PC spec listed above (Intel Celeron 1.80GHz with 2GB RAM) too slow to be running even vanilla WPF applications?

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• How to adjust microphone gain from C# (needs to work on XP & W7)...

  - by Ed

  First, note that I know there are a few questions like this already posted; however they don't seem to address the problem adequately. I have a C# application, with all the pInvoke hooks to talk to the waveXXX API, and I'm able to do capture and play back of audio with that. I'm also able to adjust speaker (WaveOut) volume with that API. The problem is that for whatever reason, that API does not allow me to adjust microphone (WaveIn) volume. So, I managed to find some mixer code that I've also pulled in and access through pInvoke and that allows me to adjust microphone volume, but only on my W7 PC. The mixer code I started with comes from here: http://social.msdn.microsoft.com/Forums/en-US/isvvba/thread/05dc2d35-1d45-4837-8e16-562ee919da85 and it works, but is written to adjust speaker volume. I added the SetMicVolume method shown here... public static void SetMicVolume(int mxid, int percentage) { bool rc; int mixer, vVolume; MIXERCONTROL volCtrl = new MIXERCONTROL(); int currentVol; mixerOpen(out mixer, mxid, 0, 0, MIXER_OBJECTF_WAVEIN); int type = MIXERCONTROL_CONTROLTYPE_VOLUME; rc = GetVolumeControl(mixer, MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, type, out volCtrl, out currentVol); if (rc == false) { mixerClose(mixer); mixerOpen(out mixer, 0, 0, 0, 0); rc = GetVolumeControl(mixer, MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, type, out volCtrl, out currentVol); if (rc == false) throw new Exception("SetMicVolume/GetVolumeControl() failed"); } vVolume = ((int)((float)(volCtrl.lMaximum - volCtrl.lMinimum) / 100.0F) * percentage); rc = SetVolumeControl(mixer, volCtrl, vVolume); if (rc == false) throw new Exception("SetMicVolume/SetVolumeControl() failed"); mixerClose(mixer); } Note the "second attempt" to call GetVolumeControl(). This is done because on XP, in the first call to GetVolumeControl (refer to site above for that code), the call to mixerGetLineControlsA() fails with XP systems returning MIXERR_INVALCONTROL. Then, with this second attempt using mixerOpen(out mixer, 0, 0, 0, 0), the code doesn't return a failure but the mic gain is unaffected. Note, as I said above, this works on W7 (the second attempt is never executed because it doesn't fail using mixerOpen(out mixer, mxid, 0, 0, MIXER_OBJECTF_WAVEIN)). I admit to not having a good grasp on the mixer API, so that's what I'm looking into now; however if anyone has a clue why this would work on W7, but not XP, I'd sure like to hear it. Meanwhile, if I figure it out before I get a response, I'll post my own answer...

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• What is the best practice to segment c#.net projects based on a single base project

  - by Anthony

  Honestly, I can't word my question any better without describing it. I have a base project (with all its glory, dlls, resources etc) which is a CMS. I need to use this project as a base for othe custom bake projects. This base project is to be maintained and updated among all custom bake projects. I use subversion (Collabnet and Tortise SVN) I have two questions: 1 - Can I use subversion to share the base project among other projects What I mean here is can I "Checkout" the base project into another "Checked Out" project and have both update and commit seperatley. So, to paint a picture, let's say I am working on a custom project and I modify the core/base prject in some way (which I know will suit the others) can I then commit those changes and upon doing so when I update the base project in the other "Checked out" resources will it pull the changes? In short, I would like not to have to manually deploy updated core files whenever I make changes into each seperate project. 2 - If I create a custom file (let's say an webcontrol or aspx page etc) can I have it compile seperatley from the base project Another tricky one to explain. When I publish my web application it creates DLLs based on the namespaces of projects attached to it. So I may have a number of DLLs including the "Website's" namespace DLL, which could simply be website. I want to be able to make a seperate, custom, control which does not compile into those DLLs as the custom files should not rely on those DLLS to run. Is it as simple to set a seperate namespace for those files like CustomFiles.ProjectName for example? Think of the whole idea as adding modules to the .NET project, I don't want the module's code in any of the core DLLs but I do need for module to be able to access the core dlls. (There is no need for the core project to access the module code as it should be one way only in theory, though I reckon it woould not be possible anyway without using JSON/SOAP or something like that, maybe I am wrong.) I want to create a pluggable environment much like that of Joomla/Wordpress as since PHP generally doesn't have to be compiled first I see this is the reason why all this is possible/easy. The idea is to allow pluggable themes, modules etc etc. (I haven't tried simply adding .NET themes after compile/publish but I am assuming this is possible anyway? OR does the compiler need to reference items in the files?)

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• whats wrong with this php mysql_real_escape_string

  - by skyhigh

  Hi Atomic Number Latin English Abbreviation * check the variables for content */ /*** a list of filters ***/ $filters = array( 'searchtext' => array( 'filter' => FILTER_CALLBACK, 'options' => 'mysql_real_escape_string'), 'fieldname' => array( 'filter' => FILTER_CALLBACK, 'options' => 'mysql_real_escape_string') ); /*** escape all POST variables ***/ $input = filter_input_array(INPUT_POST, $filters); /*** check the values are not empty ***/ if(empty($input['fieldname']) || empty($input['searchtext'])) { echo 'Invalid search'; } else { /*** mysql hostname ***/ $hostname = 'localhost'; /*** mysql username ***/ $username = 'username'; /*** mysql password ***/ $password = 'password'; /*** mysql database name ***/ $dbname = 'periodic_table'; /*** connect to the database ***/ $link = @mysql_connect($hostname, $username, $password); /*** check if the link is a valid resource ***/ if(is_resource($link)) { /*** select the database we wish to use ***/ if(mysql_select_db($dbname, $link) === TRUE) { /*** sql to SELECT information***/ $sql = sprintf("SELECT * FROM elements WHERE %s = '%s'", $input['fieldname'], $input['searchtext']); /*** echo the sql query ***/ echo '<h3>'.$sql.'</h3>'; /*** run the query ***/ $result = mysql_query($sql); /*** check if the result is a valid resource ***/ if(is_resource($result)) { /*** check if we have more than zero rows ***/ if(mysql_num_rows($result) !== 0) { echo '<table>'; while($row=mysql_fetch_array($result)) { echo '<tr> <td>'.$row['atomicnumber'].'</td> <td>'.$row['latin'].'</td> <td>'.$row['english'].'</td> <td>'.$row['abbr'].'</td> </tr>'; } echo '</table>'; } else { /*** if zero results are found.. ***/ echo 'Zero results found'; } } else { /*** if the resource is not valid ***/ 'No valid resource found'; } } /*** if we are unable to select the database show an error ****/ else { echo 'Unable to select database '.$dbname; } /*** close the connection ***/ mysql_close($link); } else { /*** if we fail to connect ***/ echo 'Unable to connect'; } } } else { echo 'Please Choose An Element'; } ? I got this code from phppro.org tutorials site and i tried to run it. It gives Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: A link to the server could not be established. .... Warning: mysql_real_escape_string() [function.mysql-real-escape-string]: Access denied for user 'ODBC'@'localhost' (using password: NO).... I went to php.net and look it up "Note: A MySQL connection is required before using mysql_real_escape_string() otherwise an error of level E_WARNING is generated, and FALSE is returned. If link_identifier isn't defined, the last MySQL connection is used." My questions are: 1-why they put single quotation around mysql_real_escape_string ? 2-They should establish a connection first, then use the $filter array statement with mysql_real_escape_string ?

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• How do I solve "405 Method Not Allowed" for our subversion setup?

  - by macke

  We're serving our source code using VisualSVN running on Windows Server 2003. Recently, we split a portion of a project into a new project in it's own repository, and then linked it back to the original project using svn:externals. Since then, we've been having issues when we try to commit files with Subclipse. The error we're getting is: svn: Commit failed (details follow): svn: PROPFIND of '/svn': 405 Method Not Allowed (https://svn.ourserver.com) Googling for a while didn't really help, our config seems to be correct. It should also be noted that we've been running this server for a while no without these problems and apart from splitting the project into two repositories, no changes have been made to the server (ie, config files are the same). It should also be noted that these errors only appear when we try to check in multiple files at once. If we check in one file at a time there are no errors. Also, it only appears in Subclipse as far as we know right now, Versions.app (OS X) seems to work fine so that is our current workaround. So, the questions is how do I analyze the error to find the cause and subsequently fix it? I'm by no means a svn guru and right now I'm clueless. EDIT: It seems we can check in multiple files in the same package, but not files from multiple packages. Also, when I "split" the project into two repositories, I imported the original repository with a new name. I did not do a dump and then import that dump. Could that be the source of our issues, and if so, how would I solve that? EDIT: After some jerking around it seems as though it is indeed related to when checking in files in different repositories. If I try to do a single commit in both Repo A and Repo B (referenced by svn:externals) at the same time, I get the error. Versions.app handles this correctly, but I guess it might just be doing two commits, not a single one. Subclipse fails miserably. For now, we simply do multiple commits, one for Repo A and one for Repo B, that works just fine. If anyone smarter than me could fill in the details why this is happening, whether or not this kind of setup is stupid etc, please go right ahead.

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• no such file to load -- rails (MissingSourceFile)... say what?!!

  - by Julian

  Hello, I'm having an obnoxious and weird problem while trying to include the ThinkingTank gem into my rails project. When I include gem 'thinkingtank' in my project's Gemfile I get the following error: ~/.rvm/gems/ree-1.8.7-2010.01/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require': no such file to load -- rails (MissingSourceFile) from ~/.rvm/gems/ree-1.8.7-2010.01/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:521:in `new_constants_in' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/activesupport-2.3.5/lib/active_support/dependencies.rb:156:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/thinkingtank-0.0.5/lib/thinkingtank.rb:1 from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:64:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:64:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:62:in `each' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:62:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:51:in `each' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler/runtime.rb:51:in `require' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/bundler-1.0.7/lib/bundler.rb:112:in `require' from ~/git/myproject/config/boot.rb:121:in `load_environment' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/rails-2.3.5/lib/initializer.rb:137:in `process' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from ~/.rvm/gems/ree-1.8.7-2010.01/gems/rails-2.3.5/lib/initializer.rb:113:in `run' from ~/git/myproject/config/environment.rb:9 from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb/init.rb:254:in `require' from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb/init.rb:254:in `load_modules' from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb/init.rb:252:in `each' from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb/init.rb:252:in `load_modules' from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb/init.rb:21:in `setup' from ~/.rvm/rubies/ree-1.8.7-2010.01/lib/ruby/1.8/irb.rb:54:in `start' from ~/.rvm/rubies/ree-1.8.7-2010.01/bin/irb:17 The output from ruby -v is: ruby 1.8.7 (2009-12-24 patchlevel 248) [i686-darwin10.6.0], MBARI 0x6770, Ruby Enterprise Edition 2010.01 And the output from rails -v is: Rails 2.3.5 I've followed the basic guidelines from their documentation and from similar SA questions. But none of issues have the rails gem going missing.. And yes, we are including rails in our Gemfile =) Thank you in advance.

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• Algorithm: Determine shape of two sectors delineated by an arbitrary path, and then fill one.

  - by Arseniy Banayev

  NOTE: This is a challenging problem for anybody who likes logic problems, etc. Consider a rectangular two-dimensional grid of height H and width W. Every space on the grid has a value, either 0 1 or 2. Initially, every space on the grid is a 0, except for the spaces along each of the four edges, which are initially a 2. Then consider an arbitrary path of adjacent (horizontally or vertically) grid spaces. The path begins on a 2 and ends on a different 2. Every space along the path is a 1. The path divides the grid into two "sectors" of 0 spaces. There is an object that rests on an unspecified 0 space. The "sector" that does NOT contain the object must be filled completely with 2. Define an algorithm that determines the spaces that must become 2 from 0, given an array (list) of values (0, 1, or 2) that correspond to the values in the grid, going from top to bottom and then from left to right. In other words, the element at index 0 in the array contains the value of the top-left space in the grid (initially a 2). The element at index 1 contains the value of the space in the grid that is in the left column, second from the top, and so forth. The element at index H contains the value of the space in the grid that is in the top row but second from the left, and so forth. Once the algorithm finishes and the empty "sector" is filled completely with 2s, the SAME algorithm must be sufficient to do the same process again. The second (and on) time, the path is still drawn from a 2 to a different 2, across spaces of 0, but the "grid" is smaller because the 2s that are surrounded by other 2s cannot be touched by the path (since the path is along spaces of 0). I thank whomever is able to figure this out for me, very very much. This does not have to be in a particular programming language; in fact, pseudo-code or just English is sufficient. Thanks again! If you have any questions, just leave a comment and I'll specify what needs to be specified.

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• Strategies for "Always-Connected" Windows Client Data Architecture

  - by magz2010

  Hi. Let me start by saying: this is my 1st post here, this is a bit lenghty, and I havent done Windows Forms development in years....with that in mind please excuse me if this isn't directly a programming question and please bear with me as I really need the help!! I have been asked to develop a Windows Forms app for our company that talks to a central (local area network) Linux Server hosting a PostgreSQL database. The app is to allow users to authenticate themselves into the system and thereafter conduct the usual transactions with the PG database. Ordinarily, I would propose writing a webforms app against Mono, but the clients need to utilise local resources such as USB peripheral devices, so that is out of the question. While it might not seem clear, my questions are italised below: Dilemma #1: The application is meant to be always connected. How should I structure my DAL/BLL - Should this reside on the server or with the client? Dilemma #2: I have been reading up on Client Application Services (CAS), and it seems like a great fit for authentication, as everything is exposed via URIs. I know that a .NET Data Provider exists for PostgreSQL, but not too sure if CAS will all work on a Linux (Debian) server? Believe me, I would get my hands dirty and try myself, but I need to come up with a logical design first before resources are allocated to me for "trial purposes"! Dilemma #3: If the DAL/BLL is to reside on the server, is there any way I can create data services, and expose only these services to authenticated clients. There is a (security) requirement whereby a connection string with username and password to the database cannot be present on any client machines...even if security on the database side is quite rigid. I'm guessing that the only way for this to work would be to create the various CRUD data service methods that are exposed by an ASP.NET app, and have the WindowsForms make a request for data or persist data to the ASP.NET app (thru a URI) and have that return a resultset or value. Would I be correct in assuming this? Should I be looking into WCF Data Services? and will WCF work with a non-SQL Server database? Thank you for taking the time out to read this, but know that I am desperately seeking any advice on this! THANKS A MILLION!!!!

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• mysql: can't set max_allowed_package to anything grater than 16MB

  - by sas

  I'm not sure if this is the right place to post these kind of questions, if it's not so, please (politely) let me know... :-) I need to save files greater than 16MB on a mysql database from a php site... I've already changed the c:\xampp\mysql\bin\my.cnf and set max_allowed_packet to 16 MB, and everything worked fine then I set it to 32 MB but there´s no way I can handle a file bigger than 16 MB I get the following error: 'MySQL server has gone away' (the same error I had when max_allowed_packet was set to 1MB) there must be some other setting that doesn´t allow me to handle files bigger than 16MB maybe the php client, I guess, but I don't know where to edit it this is the code I'm running when file.txt is smaller than 16.776.192 bytes long, it works fine, but if file.txt has 16.777.216 bytes i get the aforementioned error oh, and the field download.content is a longblob... $file = 'file.txt'; $file_handle = fopen( $file, 'r' ); $content = fread( $file_handle, filesize( $file ) ); fclose( $file_handle ); db_execute( 'truncate table download', true ); $sql = "insert into download( code, title, name, description, original_name, mime_type, size, content, user_insert_id, date_insert, user_update_id, date_update ) values ( 'new file', 'new file', 'sas.jpg', 'new file', '$file', 'mime', " . filesize( $file ) . ", '" . addslashes( $content ) . "', 0, " . db_char_to_sql( now_char(), 'datetime' ) . ", 0, " . db_char_to_sql( now_char(), 'datetime' ) . " )"; db_execute( $sql, true ); (the db_execute funcion just opens the connections and executes the sql stuff) running on windows XP sp2 server version: 5.0.67-community PHP Version 4.4.9 mysql client API version: 3.23.49 using: ApacheFriends XAMPP (Basispaket) version 1.6.8 that comes with + Apache 2.2.9 + MySQL 5.0.67 (Community Server) + PHP 5.2.6 + PHP 4.4.9 + PEAR + phpMyAdmin 2.11.9.2 ... this is part of the content of c:\xampp\mysql\bin\my.cnf # The MySQL server [mysqld] port= 3306 socket= "C:/xampp/mysql/mysql.sock" basedir="C:/xampp/mysql" tmpdir="C:/xampp/tmp" datadir="C:/xampp/mysql/data" skip-locking key_buffer = 16M # max_allowed_packet = 1M max_allowed_packet = 32M table_cache = 128 sort_buffer_size = 512K net_buffer_length = 8K read_buffer_size = 256K read_rnd_buffer_size = 512K myisam_sort_buffer_size = 8M

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• gcc optimization? bug? and its practial implication to project

  - by kumar_m_kiran

  Hi All, My questions are divided into three parts Question 1 Consider the below code, #include <iostream> using namespace std; int main( int argc, char *argv[]) { const int v = 50; int i = 0X7FFFFFFF; cout<<(i + v)<<endl; if ( i + v < i ) { cout<<"Number is negative"<<endl; } else { cout<<"Number is positive"<<endl; } return 0; } No specific compiler optimisation options are used or the O's flag is used. It is basic compilation command g++ -o test main.cpp is used to form the executable. The seemingly very simple code, has odd behaviour in SUSE 64 bit OS, gcc version 4.1.2. The expected output is "Number is negative", instead only in SUSE 64 bit OS, the output would be "Number is positive". After some amount of analysis and doing a 'disass' of the code, I find that the compiler optimises in the below format - Since i is same on both sides of comparison, it cannot be changed in the same expression, remove 'i' from the equation. Now, the comparison leads to if ( v < 0 ), where v is a constant positive, So during compilation itself, the else part cout function address is added to the register. No cmp/jmp instructions can be found. I see that the behaviour is only in gcc 4.1.2 SUSE 10. When tried in AIX 5.1/5.3 and HP IA64, the result is as expected. Is the above optimisation valid? Or, is using the overflow mechanism for int not a valid use case? Question 2 Now when I change the conditional statement from if (i + v < i) to if ( (i + v) < i ) even then, the behaviour is same, this atleast I would personally disagree, since additional braces are provided, I expect the compiler to create a temporary built-in type variable and them compare, thus nullify the optimisation. Question 3 Suppose I have a huge code base, an I migrate my compiler version, such bug/optimisation can cause havoc in my system behaviour. Ofcourse from business perspective, it is very ineffective to test all lines of code again just because of compiler upgradation. I think for all practical purpose, these kinds of error are very difficult to catch (during upgradation) and invariably will be leaked to production site. Can anyone suggest any possible way to ensure to ensure that these kind of bug/optimization does not have any impact on my existing system/code base? PS : When the const for v is removed from the code, then optimization is not done by the compiler. I believe, it is perfectly fine to use overflow mechanism to find if the variable is from MAX - 50 value (in my case).

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• Thinking about introducing PHP/MySQL into a .NET/SQL Server environment. Thoughts?

  - by abszero

  I posted this over at reddit but it didn't gain any momentum. So here is what is going on: our company was recently purchased by another web shop and I was promoted to head of development here in our office. Our office is completely .NET/SQL Server and the company who purchased us is a *nix/PHP/MySQL shop. Now several of our large clients who are on the .NET platform are up for complete rewrites (the sites are from '04 and are running on the 1.x framework.) While reviewing the proposal for one client with my superior I came across a pretty extensive module which would require several hundred man hours to complete and voiced some concern about it in relation to the quote. One of the guys from the PHP group happen to hear this and told me of a module that they (PHP Group) use in Drupal that does exactly what the proposal in front of me was describing and it only took, at most, 8 hours to completely setup / configure. My superior suggested that I take a look at Drupal and the module in question over the weekend but stressed that we should only go that route if it really made sense. So this weekend I spun up a CentOS instance in VirtualBox and started playing around with Drupal. I am still fleshing it out so don't have a solid opinion on it just yet. Anyway I have some questions / fears that I was hoping progit could help me out in! Has anyone had experience doing this and, if so, how did it turn out? I am completely ignorant to what IDE's (if any) are available to for PHP. The last time I worked with PHP it was in Notepad and that was less than intuitive. So is there are more intuitive IDE out there for PHP dev? I don't want to scare my .NET guys. Since the merger all of our new business clients that have had relatively small websites have gone on Drupal with the larger sites going on .NET. My concern is that if they see a large site go onto Drupal that they might start getting anxious and start handing out their resumes. For the foreseeable future there are no plans to liquidate the .NET platform and really we can't just from a support standpoint. What would be the best way to approach this? Any other helpful info? Thanks!

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• Doing some stuff right before the user exits the page

  - by Mike

  I have seen some questions here regarding what I want to achieve and have based what I have so far on those answer. But there is a slight misbehavior that is still irritating me. What I have is sort of a recovery feature. Whenever you are typing text, the client sends a sync request to the server every 45 seconds. It does 2 things. First, it extends the lease the client has on the record (only one person may edit at one time) for another 60 seconds. Second, it sends the text typed so far to the server in case the server crashes, internet connection fails, etc. In that case, the next time the user enters our application, the user is notified that something has gone wrong and that some text was recovered. Think of Microsoft or OpenOffice recovery whenever they crash! Of course, if the user leaves the page willingly, the user does not need to be notified and as a result, the recovery is deleted. I do that final request via a beforeunload event. Everything went fine until I was asked to make a final adjustment... The same behavior you have here at stack overflow when you exit the editor... a confirm dialogue. This works so far, BUT, the confirm dialogue is shown twice. Here is the code. The event if (local.sync.autosave_textelement) { window.onbeforeunload = exitConfirm; } The function function exitConfirm() { var local = Core; if (confirm('blub?')) { local.sync.autosave_destroy = true; sync(false); return true; } else { return false; } }; Some problem irrelevant clarifications: Core is a global Object that contains a lot of variables that are used everywhere. sync makes an ajax request. The values are based on the values that the Core.sync object contains. The parameter determines if the call should be async (default) or sync. Edit 1 I did try to separate both things (recovery deletion and user confirmation that is) into beforeunload and unload. The problem there was that unload is a bit too late. The user gets informed that there is a recovery even though it is scheduled to be deleted. If you refresh the page 1 second later, the dialogue disappears as the file was deleted by then.

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• Running daemon through rsh

  - by Max

  I want to run program as daemon in remote machine in Unix. I have rsh connection and I want the program to be running after disconnection. Suppose I have two programs: util.cpp and forker.cpp. util.cpp is some utility, for our purpose let it be just infinite root. util.cpp int main() { while (true) {}; return 0; } forker.cpp takes some program and run it in separe process through fork() and execve(): forker.cpp #include <stdio.h> #include <errno.h> #include <stdlib.h> #include <unistd.h> int main(int argc, char** argv) { if (argc != 2) { printf("./a.out <program_to_fork>\n"); exit(1); } pid_t pid; if ((pid = fork()) < 0) { perror("fork error."); exit(1); } else if (!pid) { // Child. if (execve(argv[1], &(argv[1]), NULL) == -1) { perror("execve error."); exit(1); } } else { // Parent: do nothing. } return 0; } If I run: ./forker util forker is finished very quickly, and bash 'is not paused', and util is running as daemon. But if I run: scp forker remote_server://some_path/ scp program remote_server://some_path/ rsh remote_server 'cd /some_path; ./forker program' then it is all the same (i.e. at the remote_sever forker is finishing quickly, util is running) but my bash in local machine is paused. It is waiting for util stopping (I checked it. If util.cpp is returning than it is ok.), but I don't understand why?! There are two questions: 1) Why is it paused when I run it through rsh? I am sure that I chose some stupid way to run daemon. So 2) How to run some program as daemon in C/C++ in unix-like platforms. Tnx!

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