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• Can someone explain the "use-cases" for the default munin graphs?

  - by exhuma

  When installing munin, it activates a default set of plugins (at least on ubuntu). Alternatively, you can simply run munin-node-configure to figure out which plugins are supported on your system. Most of these plugins plot straight-forward data. My question is not to explain the nature of the data (well... maybe for some) but what is it that you look for in these graphs? It is easy to install munin and see fancy graphs. But having the graphs and not being able to "read" them renders them totally useless. I am going to list standard plugins which are enabled by default on my system. So it's going to be a long list. For completeness, I am also going to list plugins which I think to understand and give a short explanation as to what I think it's used for. Pleas correct if I am wrong with any of them. So let me split this questions in three parts: Plugins where I don't even understand the data Plugins where I understand the data but don't know what I should look out for Plugins which I think to understand Plugins where I don't even understand the data These may contain questions that are not necessarily aimed at munin alone. Not understanding the data usually mean a gap in fundamental knowledge on operating systems/hardware.... ;) Feel free to respond with a "giyf" answer. These are plugins where I can only guess what's going on... I hardly want to look at these "guessing"... Disk IOs per device (IOs/second)What's an IO. I know it stands for input/output. But that's as far as it goes. Disk latency per device (Average IO wait)Not a clue what an "IO wait" is... IO Service TimeThis one is a huge mess, and it's near impossible to see something in the graph at all. Plugins where I understand the data but don't know what I should look out for IOStat (blocks/second read/written)I assume, the thing to look out for in here are spikes? Which would mean that the device is in heavy use? Available entropy (bytes)I assume that this is important for random number generation? Why would I graph this? So far the value has always been near constant. VMStat (running/I/O sleep processes)What's the difference between this one and the "processes" graph? Both show running/sleeping processes, whereas the "Processes" graph seems to have more details. Disk throughput per device (bytes/second read/written) What's thedifference between this one and the "IOStat" graph? inode table usageWhat should I look for in this graph? Plugins which I think to understand I'll be guessing some things here... correct me if I am wrong. Disk usage in percent (percent)How much disk space is used/remaining. As this is approaching 100%, you should consider cleaning up or extend the partition. This is extremely important for the root partition. Firewall Throughput (packets/second)The number of packets passing through the firewall. If this is spiking for a longer period of time, it could be a sign of a DOS attack (or we are simply recieving a large file). It can also give you an idea about your firewall performance. If it's levelling out and you need more "power" you should consider load balancing. If it's levelling out and see a correlation with your CPU load, it could also mean that your hardware is not fast enough. Correlations with disk usage could point to excessive LOG targets in you FW config. eth0 errors (packets in/out)Network errors. If this value is increasing, it could be a sign of faulty hardware. eth0 traffic (bits/second in/out)Raw network traffic. This should correlate with Firewall throughput. number of threadsAn ever-increasing value might point to a process not properly closing threads. Investigate! processesBreakdown of active processes (including sleeping). A quick spike in here might point to a fork-bomb. A slowly, but ever-increasing value might point to an application spawning sub-processes but not properly closing them. Investigate using ps faux. process priorityThis shows the distribution of process priorities. Having only high-priority processes is not of much use. Consider de-prioritizing some. cpu usageFairly straight-forward. If this is spiking, you may have an attack going on, or a process is hogging the CPU. Idf it's slowly increasing and approaching max in normal operations, you should consider upgrading your hardware (or load-balancing). file table usageNumber of actively open files. If this is reaching max, you may have a process opening, but not properly releasing files. load averageShows an summarized value for the system load. Should correlate with CPU usage. Increasing values can come from a number of sources. Look for correlations with other graphs. memory usageA graphical representation of you memory. As long as you have a lot of unused+cache+buffers you are fine. swap in/outShows the activity on your swap partition. This should always be 0. If you see activity on this, you should add more memory to your machine!

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• Python: Memory usage and optimization when modifying lists

  - by xApple

  The problem My concern is the following: I am storing a relativity large dataset in a classical python list and in order to process the data I must iterate over the list several times, perform some operations on the elements, and often pop an item out of the list. It seems that deleting one item out of a Python list costs O(N) since Python has to copy all the items above the element at hand down one place. Furthermore, since the number of items to delete is approximately proportional to the number of elements in the list this results in an O(N^2) algorithm. I am hoping to find a solution that is cost effective (time and memory-wise). I have studied what I could find on the internet and have summarized my different options below. Which one is the best candidate ? Keeping a local index: while processingdata: index = 0 while index < len(somelist): item = somelist[index] dosomestuff(item) if somecondition(item): del somelist[index] else: index += 1 This is the original solution I came up with. Not only is this not very elegant, but I am hoping there is better way to do it that remains time and memory efficient. Walking the list backwards: while processingdata: for i in xrange(len(somelist) - 1, -1, -1): dosomestuff(item) if somecondition(somelist, i): somelist.pop(i) This avoids incrementing an index variable but ultimately has the same cost as the original version. It also breaks the logic of dosomestuff(item) that wishes to process them in the same order as they appear in the original list. Making a new list: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) newlist = [] for item in somelist: if somecondition(item): newlist.append(item) somelist = newlist gc.collect() This is a very naive strategy for eliminating elements from a list and requires lots of memory since an almost full copy of the list must be made. Using list comprehensions: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist[:] = [x for x in somelist if somecondition(x)] This is very elegant but under-the-cover it walks the whole list one more time and must copy most of the elements in it. My intuition is that this operation probably costs more than the original del statement at least memory wise. Keep in mind that somelist can be huge and that any solution that will iterate through it only once per run will probably always win. Using the filter function: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist = filter(lambda x: not subtle_condition(x), somelist) This also creates a new list occupying lots of RAM. Using the itertools' filter function: from itertools import ifilterfalse while processingdata: for item in itertools.ifilterfalse(somecondtion, somelist): dosomestuff(item) This version of the filter call does not create a new list but will not call dosomestuff on every item breaking the logic of the algorithm. I am including this example only for the purpose of creating an exhaustive list. Moving items up the list while walking while processingdata: index = 0 for item in somelist: dosomestuff(item) if not somecondition(item): somelist[index] = item index += 1 del somelist[index:] This is a subtle method that seems cost effective. I think it will move each item (or the pointer to each item ?) exactly once resulting in an O(N) algorithm. Finally, I hope Python will be intelligent enough to resize the list at the end without allocating memory for a new copy of the list. Not sure though. Abandoning Python lists: class Doubly_Linked_List: def __init__(self): self.first = None self.last = None self.n = 0 def __len__(self): return self.n def __iter__(self): return DLLIter(self) def iterator(self): return self.__iter__() def append(self, x): x = DLLElement(x) x.next = None if self.last is None: x.prev = None self.last = x self.first = x self.n = 1 else: x.prev = self.last x.prev.next = x self.last = x self.n += 1 class DLLElement: def __init__(self, x): self.next = None self.data = x self.prev = None class DLLIter: etc... This type of object resembles a python list in a limited way. However, deletion of an element is guaranteed O(1). I would not like to go here since this would require massive amounts of code refactoring almost everywhere.

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• Server being used to send spam mail. How do I investigate?

  - by split_account

  Problem I think my server is being used to send spam with sendmail, I'm getting a lot of mail being queued up that I don't recognize and my mail.log and syslog are getting huge. I've shutdown sendmail, so none of it is getting out but I can't work out where it's coming from. Investigation so far: I've tried the solution in the blog post below and also shown in this thread. It's meant to add a header from wherever the mail is being added and log all all mail to file, so I changed the following lines in my php.ini file: mail.add_x_header = On mail.log = /var/log/phpmail.log But nothing is appearing in the phpmail.log. I used the command here to investigate cron jobs for all users, but nothing is out of place. The only cron being run is the cron for the website. And then I brought up all php files which had been modified in the last 30 days but none of them look suspicious. What else can I do to find where this is coming from? Mail.log reports Turned sendmail back on for second. Here is a small sample of the reports: Jun 10 14:40:30 ubuntu12 sm-mta[13684]: s5ADeQdp013684: from=<>, size=2431, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:30 ubuntu12 sm-msp-queue[13674]: s5ACK1cC011438: to=www-data, delay=01:20:14, xdelay=00:00:00, mailer=relay, pri=571670, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdp013684 Message accepted for delivery) Jun 10 14:40:30 ubuntu12 sm-mta[13719]: s5ADeQdp013684: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=32683, dsn=2.0.0, stat=Sent Jun 10 14:40:30 ubuntu12 sm-mta[13684]: s5ADeQdr013684: from=<[email protected]>, size=677, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:31 ubuntu12 sm-msp-queue[13674]: s5AC0gpi011125: to=www-data, ctladdr=www-data (33/33), delay=01:39:49, xdelay=00:00:01, mailer=relay, pri=660349, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdr013684 Message accepted for delivery) Jun 10 14:40:31 ubuntu12 sm-mta[13721]: s5ADeQdr013684: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:01, xdelay=00:00:00, mailer=local, pri=30946, dsn=2.0.0, stat=Sent Jun 10 14:40:31 ubuntu12 sm-mta[13684]: s5ADeQdt013684: from=<[email protected]>, size=677, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1] Jun 10 14:40:31 ubuntu12 sm-msp-queue[13674]: s5ACF2Nq011240: to=www-data, ctladdr=www-data (33/33), delay=01:25:29, xdelay=00:00:00, mailer=relay, pri=660349, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s5ADeQdt013684 Message accepted for delivery) Jun 10 14:40:31 ubuntu12 sm-mta[13723]: s5ADeQdt013684: to=<[email protected]>, ctladdr=<[email protected]> (33/33), delay=00:00:00, xdelay=00:00:00, mailer=local, pri=30946, dsn=2.0.0, stat=Sent Ju Further Investigation Spotted 4 spam accounts registered in the past day, which is suspicious however all have normal user privileges. There are no contact forms on the site, there are a number of forms and they take either filtered text input or plain text input. Mail is still being queued up having switched the website to maintenance mode, which blocks out everyone but the admin. Ok more investigation, it looks like the email is being send by my websites cron which runs every 5 minutes. However there are no cron jobs I've set-up which run more than once an hour and show on the website log so presumably someone has managed to edit my cron somehow. Copy of email: V8 T1402410301 K1402411201 N2 P120349 I253/1/369045 MDeferred: Connection refused by [127.0.0.1] Fbs $_www-data@localhost ${daemon_flags}c u Swww-data [email protected] MDeferred: Connection refused by [127.0.0.1] C:www-data rRFC822; [email protected] RPFD:www-data H?P?Return-Path: <?g> H??Received: (from www-data@localhost) by ubuntu12.pcsmarthosting.co.uk (8.14.4/8.14.4/Submit) id s5AEP13T015507 for www-data; Tue, 10 Jun 2014 15:25:01 +0100 H?D?Date: Tue, 10 Jun 2014 15:25:01 +0100 H?x?Full-Name: CronDaemon H?M?Message-Id: <[email protected]> H??From: root (Cron Daemon) H??To: www-data H??Subject: Cron <www-data@ubuntu12> /usr/bin/drush @main elysia-cron H??Content-Type: text/plain; charset=ANSI_X3.4-1968 H??X-Cron-Env: <PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin> H??X-Cron-Env: <COLUMNS=80> H??X-Cron-Env: <SHELL=/bin/sh> H??X-Cron-Env: <HOME=/var/www> H??X-Cron-Env: <LOGNAME=www-data>

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• Can a conforming C implementation #define NULL to be something wacky

  - by janks

  I'm asking because of the discussion that's been provoked in this thread: http://stackoverflow.com/questions/2597142/when-was-the-null-macro-not-0/2597232 Trying to have a serious back-and-forth discussion using comments under other people's replies is not easy or fun. So I'd like to hear what our C experts think without being restricted to 500 characters at a time. The C standard has precious few words to say about NULL and null pointer constants. There's only two relevant sections that I can find. First: 3.2.2.3 Pointers An integral constant expression with the value 0, or such an expression cast to type void * , is called a null pointer constant. If a null pointer constant is assigned to or compared for equality to a pointer, the constant is converted to a pointer of that type. Such a pointer, called a null pointer, is guaranteed to compare unequal to a pointer to any object or function. and second: 4.1.5 Common definitions <stddef.h> The macros are NULL which expands to an implementation-defined null pointer constant; The question is, can NULL expand to an implementation-defined null pointer constant that is different from the ones enumerated in 3.2.2.3? In particular, could it be defined as: #define NULL __builtin_magic_null_pointer Or even: #define NULL ((void*)-1) My reading of 3.2.2.3 is that it specifies that an integral constant expression of 0, and an integral constant expression of 0 cast to type void* must be among the forms of null pointer constant that the implementation recognizes, but that it isn't meant to be an exhaustive list. I believe that the implementation is free to recognize other source constructs as null pointer constants, so long as no other rules are broken. So for example, it is provable that #define NULL (-1) is not a legal definition, because in if (NULL) do_stuff(); do_stuff() must not be called, whereas with if (-1) do_stuff(); do_stuff() must be called; since they are equivalent, this cannot be a legal definition of NULL. But the standard says that integer-to-pointer conversions (and vice-versa) are implementation-defined, therefore it could define the conversion of -1 to a pointer as a conversion that produces a null pointer. In which case if ((void*)-1) would evaluate to false, and all would be well. So what do other people think? I'd ask for everybody to especially keep in mind the "as-if" rule described in 2.1.2.3 Program execution. It's huge and somewhat roundabout, so I won't paste it here, but it essentially says that an implementation merely has to produce the same observable side-effects as are required of the abstract machine described by the standard. It says that any optimizations, transformations, or whatever else the compiler wants to do to your program are perfectly legal so long as the observable side-effects of the program aren't changed by them. So if you are looking to prove that a particular definition of NULL cannot be legal, you'll need to come up with a program that can prove it. Either one like mine that blatantly breaks other clauses in the standard, or one that can legally detect whatever magic the compiler has to do to make the strange NULL definition work. Steve Jessop found an example of way for a program to detect that NULL isn't defined to be one of the two forms of null pointer constants in 3.2.2.3, which is to stringize the constant: #define stringize_helper(x) #x #define stringize(x) stringize_helper(x) Using this macro, one could puts(stringize(NULL)); and "detect" that NULL does not expand to one of the forms in 3.2.2.3. Is that enough to render other definitions illegal? I just don't know. Thanks!

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• ie9/CSS: Flyout menu not working in ie9, but looks great in Firefox/Chrome

  - by Brandon

  Please see this flyout menu: http://www.caseen.com/store.html. It looks amazing in both Firefox and Chrome, but not in IE9! Trying to see what is going on =(. It looks like ie9 is completing ignoring the stylesheet, but in error checking and clicking ie9 direct mode, it shows up however VERY ugly with huge nasty white borders around the links! Please see my code: <div class="flyout"> <ul> <!--START: CATEGORIES--> <!--START: CATEGORY_FORMAT--> <li><a href="view_category.asp?cat=CATID">&nbsp;CATEGORY</a> <!--END: CATEGORY_FORMAT--> <ul><!--START: SUB_CATEGORY_FORMAT--> <li><a href="view_category.asp?cat=CATID">&nbsp;CATEGORY</a></li> <!--END: SUB_CATEGORY_FORMAT--></ul> <!--END: CATEGORIES--> </li> </ul> </div> AND CSS .flyout { width: 130px; height: auto; position:relative; margin: -10 0; padding: 0; z-index:10000; } .flyout ul li a { display:block; text-decoration:none; color: #fff; width: 130px; border: solid; border-color: #000; border-width: 0 0 0 5px; text-align:left; font-size:12px; line-height: 25px; } .flyout ul { padding:0px; list-style-type: none; } .flyout ul li { float:left; margin-right:1px; position:relative; } .flyout ul li ul { display: none; } .flyout ul li:hover a { border: solid; border-color: #fff; border-width: 0 2 0 5px; color: #60dfe5; } .flyout ul li:hover ul { display:block; position:absolute; top:0; left:130px; width:10px; } .flyout ul li:hover ul li a.hide { background:#000; color:#fff; } .flyout ul li:hover ul li:hover a.hide {width:180px;} .flyout ul li:hover ul li ul {display: none;} .flyout ul li:hover ul li a { display:block; background:#000; color:#60dfe5; width:200px; } .flyout ul li:hover ul li a:hover { background:#000; color:#fff; } Thanks, Brandon

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• Random Complete System Unresponsiveness Running Mathematical Functions

  - by Computer Guru

  I have a program that loads a file (anywhere from 10MB to 5GB) a chunk at a time (ReadFile), and for each chunk performs a set of mathematical operations (basically calculates the hash). After calculating the hash, it stores info about the chunk in an STL map (basically <chunkID, hash>) and then writes the chunk itself to another file (WriteFile). That's all it does. This program will cause certain PCs to choke and die. The mouse begins to stutter, the task manager takes 2 min to show, ctrl+alt+del is unresponsive, running programs are slow.... the works. I've done literally everything I can think of to optimize the program, and have triple-checked all objects. What I've done: Tried different (less intensive) hashing algorithms. Switched all allocations to nedmalloc instead of the default new operator Switched from stl::map to unordered_set, found the performance to still be abysmal, so I switched again to Google's dense_hash_map. Converted all objects to store pointers to objects instead of the objects themselves. Caching all Read and Write operations. Instead of reading a 16k chunk of the file and performing the math on it, I read 4MB into a buffer and read 16k chunks from there instead. Same for all write operations - they are coalesced into 4MB blocks before being written to disk. Run extensive profiling with Visual Studio 2010, AMD Code Analyst, and perfmon. Set the thread priority to THREAD_MODE_BACKGROUND_BEGIN Set the thread priority to THREAD_PRIORITY_IDLE Added a Sleep(100) call after every loop. Even after all this, the application still results in a system-wide hang on certain machines under certain circumstances. Perfmon and Process Explorer show minimal CPU usage (with the sleep), no constant reads/writes from disk, few hard pagefaults (and only ~30k pagefaults in the lifetime of the application on a 5GB input file), little virtual memory (never more than 150MB), no leaked handles, no memory leaks. The machines I've tested it on run Windows XP - Windows 7, x86 and x64 versions included. None have less than 2GB RAM, though the problem is always exacerbated under lower memory conditions. I'm at a loss as to what to do next. I don't know what's causing it - I'm torn between CPU or Memory as the culprit. CPU because without the sleep and under different thread priorities the system performances changes noticeably. Memory because there's a huge difference in how often the issue occurs when using unordered_set vs Google's dense_hash_map. What's really weird? Obviously, the NT kernel design is supposed to prevent this sort of behavior from ever occurring (a user-mode application driving the system to this sort of extreme poor performance!?)..... but when I compile the code and run it on OS X or Linux (it's fairly standard C++ throughout) it performs excellently even on poor machines with little RAM and weaker CPUs. What am I supposed to do next? How do I know what the hell it is that Windows is doing behind the scenes that's killing system performance, when all the indicators are that the application itself isn't doing anything extreme? Any advice would be most welcome.

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• Link Error : xxx is already defined in *****.LIB :: What exactly is wrong?

  - by claws

  Problem: I'm trying to use a library named DCMTK which used some other external libraries ( zlib, libtiff, libpng, libxml2, libiconv ). I've downloaded these external libraries (*.LIB & *.h files ) from the same website. Now, when I compile the DCMTK library I'm getting link errors (793 errors) like this: Error 2 error LNK2005: __encode_pointer already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 3 error LNK2005: __decode_pointer already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 4 error LNK2005: __CrtSetCheckCount already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 5 error LNK2005: __invoke_watson already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 6 error LNK2005: __errno already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 7 error LNK2005: __configthreadlocale already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Error 8 error LNK2005: _exit already defined in MSVCRTD.lib(MSVCR90D.dll) LIBCMTD.lib dcmmkdir Documentation: This seems to be a popular error for this library so, they do have a FAQ entry addressing this issue which ( http://forum.dcmtk.org/viewtopic.php?t=35 ) says: The problem is that the linker tries to combine different, incompatible versions of the Visual C++ runtime library into a single binary. This happens when not all parts of your project and the libraries you link against are generated with the same code generation options in Visual C++. Do not use the /NODEFAULTLIB workaround, because strange software crashes may follow. Fix the problem! DCMTK is by default compiled with the "Multithreaded" or "Multithreaded Debug" code generation option (the latter for Debug mode). Either change the project settings of all of your code to use these code generation options, or change the code generation for all DCMTK modules and re-compile. MFC users beware: DCMTK should be compiled with "Multithreaded DLL" or "Multithreaded DLL Debug" settings if you want to link the libraries into an MFC application. Solution to same problem for others: http://stackoverflow.com/questions/2259697/vscopengl-huge-amount-of-linker-issues-with-release-build-only says: It seems that your release build is trying to link to something that was built debug. You probably have a broken dependency in your build, (or you missed rebuilding something to release by hand if your project is normally built in pieces). More technically, you seem to be linking projects built with different C Run Time library settings, one with "Multi-Threaded", another one with "Multi-Threaded Debug". Adjust the settings for all the projects to use the very same flavour of the library and the issue should go away Questions: Till now I used to think that Name mangling is the only problem that may cause linking failures if its not been standardized. Just now I knew there are other things also which can cause same effect. Whats up with the "Debug Mode" (Multi-Threaded Debug) and "Release Mode" (Multi-Threaded)? What exactly is happening under the hood? Why exactly this thing is causing linking error? I wonder if there is something called "Single-Threaded Debug" and "Single-Threaded" which again causes the same thing. Documentation talks something about "Code Generation Options". What Code Generation Options? WTH are they? Documentation specifically warns us not to use /NODEFAULTLIB workaround. (example /NODEFAULTLIB :msvcrt ). Why? How would I cause troubles? what exactly is it? Please explain the last point in the documentation for MFC users. Because I'm going to use MFC later in this project. Explain Why should we do it? What troubles would it cause if I don't. Anything more you'd like to mention? I mean regarding similar errors. I'm very interested in Linker & its problems. So, if there are any similar things you can mentions them or some keywords atleast.

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• Where do I start ?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Rendering a Long Document on iPad

  - by benjismith

  I'm implementing a document viewer with highlighting/annotation capabilities for a custom document format on iPad. The documents are kind of long (100 to 200 pages, if printed on paper) and I've had a hard time finding the right approach. Here are the requirments: 1) Basic rich-text styling: control of left/right margins. Control of font name, size, foreground/background color, and line spacing. Bold, italics, underline, etc. 2) Selection and highlighting of arbitrary text regions (not limited to paragraph boundaries, like in Safari/UIWebView). 3) Customization of the Cut/Copy/Paste popup (what is that thing called anyhow? UIActionBar?) This is one of the essential requirements of the app. My first implementation was based on UIWebView. I just rendered the document as HTML with CSS for text styling. But I couldn't get the kind of text selection behavior I wanted (across paragraph boundaries) and the UIActionBar can't be customized from within UIWebView. So I started working on a javascript approach, faking the device text-selection behavior using JQuery to trap touch events and dynamically modifying the DOM to change the background color of selected regions of text. I built a fake UIActionBar control as a hidden DIV, positioning it and unhiding it whenever there was an active selection region. Not too shabby. The main problem is that it's SLOOOOOOOW. Scrolling through the document is nice and quick, but dynamically changing the DOM is not very snappy. Plus, I couldn't figure out how to recreate the magnifier loupe, so my fake text-selection GUI doesn't look quite the same as the native implementation. Also, I haven't yet implemented the communication bridge between the javascript layer and the objective-c layer (where the rest of the app lives), but it was shaping up to be a huge hassle. So I've been looking at CoreText, but there are precious few examples on the web. I spent a little time with this simple little demo: http://github.com/jonasschnelli/I7CoreTextExample/ It shows how to use CoreText to draw an NSAttributedText string into a UIView. But it has its own problems: It doesn't implement text-selection behavior, and it doesn't present a UIActionBar, so I don't have any idea how to make that happen. And, more importantly, it tries to draw the entire document all at once, with significant performance degradations for long documents. My documents can have thousands of paragraphs, and less than 1% of the document is ever on screen at a time. On the plus side, these documents already contain precise formatting information. I know the exact page-position of every line of text, so I don't need a layout engine. Does anyone know how to implement this sort of view using CoreText? I understand that a full-fledged implementation is overkill for a question like this, but I'm looking for a good CoreText example with a few basic requirements: 1) Precise layout & formatting control (using the formatting metrics and text styles I've already calculated). 2) Arbitrary selection of text. 3) Customization of the UIActionBar. 4) Efficient recycling of resources for off-screen objects. I'd be happy to implement my own recycling when text elements scroll off-screen, but wouldn't that require re-implementing UIScrollView? I'm brand-new to iPhone development, and still getting used to Objective-C, but I've been working in other languages (Java, C#, flex/actionscript, etc) for more than ten years, so I feel confident in my ability to get the work done, if only I had a better feel for the iPhone SDK and the common coding patterns for stuff like this. Is it just me, or does the SDK documentation really suck? Anyhow, thanks for your help!

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• Need help identiying a nasty rootkit in Windows

  - by goofrider

  I have a nasty rootkit that not tools seem to be able to idenity. I know for sure it's a rootkit, but I can figure out which rootkit it is. Here's what I gathered so far: It creates multiple copies of itself in %HOME%\Local Settings\Temp with names like Q.EXE, IAJARZ.exe, etc., and install them as hidden services. These EXE have SysInternals identifiers in them so they're definitely rootkits. It hooked very deep in the system, including file read/write, security policies, registry read/write, and possibly WinSock/TCP/IP. When going to Sophos.com to download their software, the rootkit inject something called Microsoft Ajax Tootkit into the page, which injects code into the email submission form in order to redirect it. (EDIT: I might have panicked. Looks like Sophos does use an AJAZ email form, their form is just broken on Chrome so it looked like a mail form injection attack, the link is http://www.sophos.com/en-us/products/free-tools/virus-removal-tool/download.aspx ) Super-Antispyware found a lot of spyware cookies, in the name of .kaspersky.2o7.net, etc. (just chedk 2o7.net, looks like it's a legit ad company) I tried comparing DNS lookup from the infected systems and from system in other physical locations, no DNS redirections it seems. I used dd to copy the MBR and compared it with the MBR provided by ms-sys package, no differences so it's not infecting MBR. No antivirus or rootkit scanner be able to identify it. Most of them can't even find it. I tried scanning, in-situ (normal mode), in safe mode, and boot to linux live CD. Scanners used: Avast, Sophos anti rootkit, Kasersky TDSSKiller, GMER, RootkitRevealer, and many others. Kaspersky reported some unsigned system files that ought to be signed (e.g. tcpip.sys), and reported a number of MD5 mismatches. But otherwise couldn't identify anything based on signature. When running Sysinternal RootkitRevealer and Sophos AntiRootkit, CPU usage goes up to 100% and gets stucked. The Rootkit is blocking them. When trying running/installing HiJackThis, RootkitRevealer and some other scanners, it tells me system security policy prevent running/installing it. The list of malicious acitivities go on and on. here's a sample of logs from all my scans. In particular, aswSnx.SYS, apnenfno.sys and PROCMON20.SYS has a huge number of hooks. It's hard to tell if the rootkit replaced legit program files like aswSnx.SYS (from Avast) and PROCMON20.SYS (from Sysinternal Process Monitor). I can't find whether apnenfno.sys is from a legit program. Help to identify it is appreciated. Trend Micro RootkitBuster ------ [HIDDEN_REGISTRY][Hidden Reg Value]: KeyPath : HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\sptd\Cfg Root : 586bfc0 SubKey : Cfg ValueName : g0 Data : 38 23 E8 D0 BF F2 2D 6F ... ValueType : 3 AccessType: 0 FullLength: 61 DataSize : 32 [HOOKED_SERVICE_API]: Service API : ZwCreateMutant Image Path : C:\WINDOWS\System32\Drivers\aswSnx.SYS OriginalHandler : 0x8061758e CurrentHandler : 0xaa66cce8 ServiceNumber : 0x2b ModuleName : aswSnx.SYS SDTType : 0x0 [HOOKED_SERVICE_API]: Service API : ZwCreateThread Image Path : c:\windows\system32\drivers\apnenfno.sys OriginalHandler : 0x805d1038 CurrentHandler : 0xaa5f118c ServiceNumber : 0x35 ModuleName : apnenfno.sys SDTType : 0x0 [HOOKED_SERVICE_API]: Service API : ZwDeleteKey Image Path : C:\WINDOWS\system32\Drivers\PROCMON20.SYS OriginalHandler : 0x80624472 CurrentHandler : 0xa709b0f8 ServiceNumber : 0x3f ModuleName : PROCMON20.SYS SDTType : 0x0 HiJackThis ------ O23 - Service: JWAHQAGZ - Sysinternals - www.sysinternals.com - C:\DOCUME~1\jeff\LOCALS~1\Temp\JWAHQAGZ.exe O23 - Service: LHIJ - Sysinternals - www.sysinternals.com - C:\DOCUME~1\jeff\LOCALS~1\Temp\LHIJ.exe Kaspersky TDSSKiller ------ 21:05:58.0375 3936 C:\WINDOWS\system32\ati2sgag.exe - copied to quarantine 21:05:59.0217 3936 ATI Smart ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:05:59.0342 3936 C:\WINDOWS\system32\BUFADPT.SYS - copied to quarantine 21:05:59.0856 3936 BUFADPT ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:05:59.0965 3936 C:\Program Files\CrashPlan\CrashPlanService.exe - copied to quarantine 21:06:00.0152 3936 CrashPlanService ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:00.0246 3936 C:\WINDOWS\system32\epmntdrv.sys - copied to quarantine 21:06:00.0433 3936 epmntdrv ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:00.0464 3936 C:\WINDOWS\system32\EuGdiDrv.sys - copied to quarantine 21:06:00.0526 3936 EuGdiDrv ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:00.0604 3936 C:\Program Files\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService.exe - copied to quarantine 21:06:01.0181 3936 FLEXnet Licensing Service ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:01.0321 3936 C:\Program Files\AddinForUNCFAT\UNCFATDMS.exe - copied to quarantine 21:06:01.0430 3936 OTFSDMS ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:01.0492 3936 C:\WINDOWS\system32\DRIVERS\tcpip.sys - copied to quarantine 21:06:01.0539 3936 Tcpip ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:01.0601 3936 C:\DOCUME~1\jeff\LOCALS~1\Temp\TULPUWOX.exe - copied to quarantine 21:06:01.0664 3936 HKLM\SYSTEM\ControlSet003\services\TULPUWOX - will be deleted on reboot 21:06:01.0664 3936 C:\DOCUME~1\jeff\LOCALS~1\Temp\TULPUWOX.exe - will be deleted on reboot 21:06:01.0664 3936 TULPUWOX ( UnsignedFile.Multi.Generic ) - User select action: Delete 21:06:01.0757 3936 C:\WINDOWS\system32\Drivers\usbaapl.sys - copied to quarantine 21:06:01.0866 3936 USBAAPL ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:01.0913 3936 C:\Program Files\VMware\VMware Player\vmware-authd.exe - copied to quarantine 21:06:02.0443 3936 VMAuthdService ( UnsignedFile.Multi.Generic ) - User select action: Quarantine 21:06:02.0443 3936 vmount2 ( UnsignedFile.Multi.Generic ) - skipped by user 21:06:02.0443 3936 vmount2 ( UnsignedFile.Multi.Generic ) - User select action: Skip 21:06:02.0459 3936 vstor2 ( UnsignedFile.Multi.Generic ) - skipped by user 21:06:02.0459 3936 vstor2 ( UnsignedFile.Multi.Generic ) - User select action: Skip

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• how to speed up the code??

  - by kaushik

  i have very huge code about 600 lines plus. cant post the whole thing here. but a particular code snippet is taking so much time,leading to problems. here i post that part of code please tell me what to do speed up the processing.. please suggest the part which may be the reason and measure to improve them if this small part of code is understandable. using_data={} def join_cost(a , b): global using_data #print a #print b save_a=[] save_b=[] print 1 #for i in range(len(m)): #if str(m[i][0])==str(a): save_a=database_index[a] #for i in range(len(m)): # if str(m[i][0])==str(b): #print 'save_a',save_a #print 'save_b',save_b print 2 save_b=database_index[b] using_data[save_a[0]]=save_a s=str(save_a[1]).replace('phone','text') s=str(s)+'.pm' p=os.path.join("c:/begpython/wavnk/",s) x=open(p , 'r') print 3 for i in range(6): x.readline() k2='a' j=0 o=[] while k2 is not '': k2=x.readline() k2=k2.rstrip('\n') oj=k2.split(' ') o=o+[oj] #print o[j] j=j+1 #print j #print o[2][0] temp=long(1232332) end_time=save_a[4] #print end_time k=(j-1) for i in range(k): diff=float(o[i][0])-float(end_time) if diff<0: diff=diff*(-1) if temp>diff: temp=diff pm_row=i #print pm_row #print temp #print o[pm_row] #pm_row=3 q=[] print 4 l=str(p).replace('.pm','.mcep') z=open(l ,'r') for i in range(pm_row): z.readline() k3=z.readline() k3=k3.rstrip('\n') q=k3.split(' ') #print q print 5 s=str(save_b[1]).replace('phone','text') s=str(s)+'.pm' p=os.path.join("c:/begpython/wavnk/",s) x=open(p , 'r') for i in range(6): x.readline() k2='a' j=0 o=[] while k2 is not '': k2=x.readline() k2=k2.rstrip('\n') oj=k2.split(' ') o=o+[oj] #print o[j] j=j+1 #print j #print o[2][0] temp=long(1232332) strt_time=save_b[3] #print strt_time k=(j-1) for i in range(k): diff=float(o[i][0])-float(strt_time) if diff<0: diff=diff*(-1) if temp>diff: temp=diff pm_row=i #print pm_row #print temp #print o[pm_row] #pm_row=3 w=[] l=str(p).replace('.pm','.mcep') z=open(l ,'r') for i in range(pm_row): z.readline() k3=z.readline() k3=k3.rstrip('\n') w=k3.split(' ') #print w cost=0 for i in range(12): #print q[i] #print w[i] h=float(q[i])-float(w[i]) cost=cost+math.pow(h,2) j_cost=math.sqrt(cost) #print cost return j_cost def target_cost(a , b): a=(b+1)*3 b=(a+1)*2 t_cost=(a+b)*5/2 return t_cost r1='shht:ra_77' r2='grx_18' g=[] nodes=[] nodes=nodes+[[r1]] for i in range(len(y_in_db_format)): g=y_in_db_format[i] #print g #print g[0] g.remove(str(g[0])) nodes=nodes+[g] nodes=nodes+[[r2]] print nodes print "lenght of nodes",len(nodes) lists=[] #lists=lists+[r1] for i in range(len(nodes)): for j in range(len(nodes[i])): lists=lists+[nodes[i][j]] #lists=lists+[r2] print lists distance={} for i in range(len(lists)): if i==0: distance[str(lists[i])]=0 else: distance[str(lists[i])]=long(123231223) #print distance group_dist=[] infinity=long(123232323) for i in range(len(nodes)): distances=[] for j in range(len(nodes[i])): #distances=[] if i==0: distances=distances+[[nodes[i][j], 0]] else: distances=distances+[[nodes[i][j],infinity]] group_dist=group_dist+[distances] #print distances print "group_distances",group_dist #print "check",group_dist[0][0][1] #costs={} #for i in range(len(lists)): #if i==0: # costs[str(lists[i])]=1 #else: # costs[str(lists[i])]=get_selfcost(lists[i]) path=[] for i in range(len(nodes)): mini=[] if i!=(len(nodes)-1): #temp=long(123234324) #Now calculate the cost between the current node and each of its neighbour for k in range(len(nodes[(i+1)])): for j in range(len(nodes[i])): current=nodes[i][j] #print "current_node",current j_distance=join_cost( current , nodes[i+1][k]) #t_distance=target_cost( current , nodes[i+1][k]) t_distance=34 #print distance #print "distance between current and neighbours",distance total_distance=(.5*(float(group_dist[i][j][1])+float(j_distance))+.5*(float(t_distance))) #print "total distance between the intial_nodes and current neighbour",total_distance if int(group_dist[i+1][k][1]) > int(total_distance): group_dist[i+1][k][1]=total_distance #print "updated distance",group_dist[i+1][k][1] a=current #print "the neighbour",nodes[i+1][k],"updated the value",a mini=mini+[[str(nodes[i+1][k]),a]] print mini

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• MySQL and INT auto_increment fields

  - by PHPguy

  Hello folks, I'm developing in LAMP (Linux+Apache+MySQL+PHP) since I remember myself. But one question was bugging me for years now. I hope you can help me to find an answer and point me into the right direction. Here is my challenge: Say, we are creating a community website, where we allow our users to register. The MySQL table where we store all users would look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; So, from this snippet you can see that we have a unique and automatically incrementing for every new user 'uid' field. As on every good and loyal community website we need to provide users with possibility to completely delete their profile if they want to cancel their participation in our community. Here comes my problem. Let's say we have 3 registered users: Alice (uid = 1), Bob (uid = 2) and Chris (uid = 3). Now Bob want to delete his profile and stop using our community. If we delete Bob's profile from the 'users' table then his missing 'uid' will create a gap which will be never filled again. In my opinion it's a huge waste of uid's. I see 3 possible solutions here: 1) Increase the capacity of the 'uid' field in our table from SMALLINT (int(2)) to, for example, BIGINT (int(8)) and ignore the fact that some of the uid's will be wasted. 2) introduce the new field 'is_deleted', which will be used to mark deleted profiles (but keep them in the table, instead of deleting them) to re-utilize their uid's for newly registered users. The table will look then like this: CREATE TABLE `users` ( `uid` int(2) unsigned NOT NULL auto_increment COMMENT 'User ID', `name` varchar(20) NOT NULL, `password` varchar(32) NOT NULL COMMENT 'Password is saved as a 32-bytes hash, never in plain text', `email` varchar(64) NOT NULL, `is_deleted` int(1) unsigned NOT NULL default '0' COMMENT 'If equal to "1" then the profile has been deleted and will be re-used for new registrations', `created` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of registration', `updated` int(11) unsigned NOT NULL default '0' COMMENT 'Timestamp of profile update, e.g. change of email', PRIMARY KEY (`uid`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; 3) Write a script to shift all following user records once a previous record has been deleted. E.g. in our case when Bob (uid = 2) decides to remove his profile, we would replace his record with the record of Chris (uid = 3), so that uid of Chris becomes qual to 2 and mark (is_deleted = '1') the old record of Chris as vacant for the new users. In this case we keep the chronological order of uid's according to the registration time, so that the older users have lower uid's. Please, advice me now which way is the right way to handle the gaps in the auto_increment fields. This is just one example with users, but such cases occur very often in my programming experience. Thanks in advance!

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• Thread locking issue with FileHelpers between calling engine.ReadNext() method and readign engine.Li

  - by Rad

  I use producer/consumer pattern with FileHelpers library to import data from one file (which can be huge) using multiple threads. Each thread is supposed to import a chunk of that file and I would like to use LineNumber property of the FileHelperAsyncEngine instance that is reading the file as primary key for imported rows. FileHelperAsyncEngine internally has an IEnumerator IEnumerable.GetEnumerator(); which is iterated over using engine.ReadNext() method. That internally sets LineNumber property (which seems is not thread safe). Consumers will have Producers assiciated with them that will supply DataTables to Consumers which will consume them via SqlBulkLoad class which will use IDataReader implementation which will iterate over a collection of DataTables which are internal to a Consumer instance. Each instance of will have one SqlBulkCopy instance associate with it. I have thread locking issue. Below is how I create multiple Producer threads. I start each thread afterwords. Produce method on a producer instance will be called determining which chunk of input file will be processed. It seems that engine.LineNumber is not thread safe and I doesn't import a proper LineNumber in the database. It seems that by the time engine.LineNumber is read some other thread called engine.ReadNext() and changed engine.LineNumber property. I don't want to lock the loop that is supposed to process a chunk of input file because I loose parallelism. How to reorganize the code to solve this threading issue? Thanks Rad for (int i = 0; i < numberOfProducerThreads; i++) DataConsumer consumer = dataConsumers[i]; //create a new producer DataProducer producer = new DataProducer(); //consumer has already being created consumer.Subscribe(producer); FileHelperAsyncEngine orderDetailEngine = new FileHelperAsyncEngine(recordType); orderDetailEngine.Options.RecordCondition.Condition = RecordCondition.ExcludeIfBegins; orderDetailEngine.Options.RecordCondition.Selector = STR_ORDR; int skipLines = i * numberOfBufferTablesToProcess * DataBuffer.MaxBufferRowCount; Thread newThread = new Thread(() => { producer.Produce(consumer, inputFilePath, lineNumberFieldName, dict, orderDetailEngine, skipLines, numberOfBufferTablesToProcess); consumer.SetEndOfData(producer); }); producerThreads.Add(newThread); thread.Start();} public void Produce(DataConsumer consumer, string inputFilePath, string lineNumberFieldName, Dictionary<string, object> dict, FileHelperAsyncEngine engine, int skipLines, int numberOfBufferTablesToProcess) { lock (this) { engine.Options.IgnoreFirstLines = skipLines; engine.BeginReadFile(inputFilePath); } int rowCount = 1; DataTable buffer = consumer.BufferDataTable; while (engine.ReadNext() != null) { lock (this) { dict[lineNumberFieldName] = engine.LineNumber; buffer.Rows.Add(ObjectFieldsDataRowMapper.MapObjectFieldsToDataRow(engine.LastRecord, dict, buffer)); if (rowCount % DataBuffer.MaxBufferRowCount == 0) { consumer.AddBufferDataTable(buffer); buffer = consumer.BufferDataTable; } if (rowCount % (numberOfBufferTablesToProcess * DataBuffer.MaxBufferRowCount) == 0) { break; } rowCount++; } } if (buffer.Rows.Count > 0) { consumer.AddBufferDataTable(buffer); } engine.Close(); }

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• How best to modernize the 2002-era J2EE app?

  - by user331465

  I have this friend.... I have this friend who works on a java ee application (j2ee) application started in the early 2000's. Currently they add a feature here and there, but have a large codebase. Over the years the team has shrunk by 70%. [Yes, the "i have this friend is". It's me, attempting to humorously inject teenage high-school counselor shame into the mix] Java, Vintage 2002 The application uses EJB 2.1, struts 1.x, DAO's etc with straight jdbc calls (mixture of stored procedures and prepared statements). No ORM. For caching they use a mixture of OpenSymphony OSCache and a home-grown cache layer. Over the last few years, they have spent effort to modernize the UI using ajax techniques and libraries. This largely involves javascript libaries (jquery, yui, etc). Client Side On the client side, the lack of upgrade path from struts1 to struts2 discouraged them from migrating to struts2. Other web frameworks became popular (wicket, spring , jsf). Struts2 was not the "clear winner". Migrating all the existing UI from Struts1 to Struts2/wicket/etc did not seem to present much marginal benefit at a very high cost. They did not want to have a patchwork of technologies-du-jour (subsystem X in Struts2, subsystem Y in Wicket, etc.) so developer write new features using Struts 1. Server Side On the server side, they looked into moving to ejb 3, but never had a big impetus. The developers are all comfortable with ejb-jar.xml, EJBHome, EJBRemote, that "ejb 2.1 as is" represented the path of least resistance. One big complaint about the ejb environment: programmers still pretend "ejb server runs in separate jvm than servlet engine". No app server (jboss/weblogic) has ever enforced this separation. The team has never deployed the ejb server on a separate box then the app server. The ear file contains multiple copies of the same jar file; one for the 'web layer' (foo.war/WEB-INF/lib) and one for the server side (foo.ear/). The app server only loads one jar. The duplications makes for ambiguity. Caching As for caching, they use several cache implementations: OpenSymphony cache and a homegrown cache. Jgroups provides clustering support Now What? The question: The team currently has spare cycles to to invest in modernizing the application? Where would the smart investor spend them? The main criteria: 1) productivity gains. Specifically reducing the time to develope new subsystems features and reduced maintenance. 2) performance/scalability. They do not care about fashion or techno-du-jour street cred. What do you all recommend? On the persistence side Switch everything (or new development only) to JPA/JPA2? Straight hibernate? Wait for Java EE 6? On the client/web-framework side: Migrate (some or all) to struts2? wicket? jsf/jsf2? As for caching: terracotta? ehcache? coherence? stick with what they have? how best to take advantage of the huge heap sizes that the 64-bit jvms offer? Thanks in advance.

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• How to figure out who owns a worker thread that is still running when my app exits?

  - by Dave

  Not long after upgrading to VS2010, my application won't shut down cleanly. If I close the app and then hit pause in the IDE, I see this: The problem is, there's no context. The call stack just says [External code], which isn't too helpful. Here's what I've done so far to try to narrow down the problem: deleted all extraneous plugins to minimize the number of worker threads launched set breakpoints in my code anywhere I create worker threads (and delegates + BeginInvoke, since I think they are labeled "Worker Thread" in the debugger anyway). None were hit. set IsBackground = true for all threads While I could do the next brute force step, which is to roll my code back to a point where this didn't happen and then look over all of the change logs, this isn't terribly efficient. Can anyone recommend a better way to figure this out, given the notable lack of information presented by the debugger? The only other things I can think of include: read up on WinDbg and try to use it to stop anytime a thread is started. At least, I thought that was possible... :) comment out huge blocks of code until the app closes properly, then start uncommenting until it doesn't. UPDATE Perhaps this information will be of use. I decided to use WinDbg and attach to my application. I then closed it, and switched to thread 0 and dumped the stack contents. Here's what I have: ThreadCount: 6 UnstartedThread: 0 BackgroundThread: 1 PendingThread: 0 DeadThread: 4 Hosted Runtime: no PreEmptive GC Alloc Lock ID OSID ThreadOBJ State GC Context Domain Count APT Exception 0 1 1c70 005a65c8 6020 Enabled 02dac6e0:02dad7f8 005a03c0 0 STA 2 2 1b20 005b1980 b220 Enabled 00000000:00000000 005a03c0 0 MTA (Finalizer) XXXX 3 08504048 19820 Enabled 00000000:00000000 005a03c0 0 Ukn XXXX 4 08504540 19820 Enabled 00000000:00000000 005a03c0 0 Ukn XXXX 5 08516a90 19820 Enabled 00000000:00000000 005a03c0 0 Ukn XXXX 6 08517260 19820 Enabled 00000000:00000000 005a03c0 0 Ukn 0:008> ~0s eax=c0674960 ebx=00000000 ecx=00000000 edx=00000000 esi=0040f320 edi=005a65c8 eip=76c37e47 esp=0040f23c ebp=0040f258 iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202 USER32!NtUserGetMessage+0x15: 76c37e47 83c404 add esp,4 0:000> !clrstack OS Thread Id: 0x1c70 (0) Child SP IP Call Site 0040f274 76c37e47 [InlinedCallFrame: 0040f274] 0040f270 6baa8976 DomainBoundILStubClass.IL_STUB_PInvoke(System.Windows.Interop.MSG ByRef, System.Runtime.InteropServices.HandleRef, Int32, Int32)*** WARNING: Unable to verify checksum for C:\Windows\assembly\NativeImages_v4.0.30319_32\WindowsBase\d17606e813f01376bd0def23726ecc62\WindowsBase.ni.dll 0040f274 6ba924c5 [InlinedCallFrame: 0040f274] MS.Win32.UnsafeNativeMethods.IntGetMessageW(System.Windows.Interop.MSG ByRef, System.Runtime.InteropServices.HandleRef, Int32, Int32) 0040f2c4 6ba924c5 MS.Win32.UnsafeNativeMethods.GetMessageW(System.Windows.Interop.MSG ByRef, System.Runtime.InteropServices.HandleRef, Int32, Int32) 0040f2dc 6ba8e5f8 System.Windows.Threading.Dispatcher.GetMessage(System.Windows.Interop.MSG ByRef, IntPtr, Int32, Int32) 0040f318 6ba8d579 System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame) 0040f368 6ba8d2a1 System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame) 0040f374 6ba7fba0 System.Windows.Threading.Dispatcher.Run() 0040f380 62e6ccbb System.Windows.Application.RunDispatcher(System.Object)*** WARNING: Unable to verify checksum for C:\Windows\assembly\NativeImages_v4.0.30319_32\PresentationFramewo#\7f91eecda3ff7ce478146b6458580c98\PresentationFramework.ni.dll 0040f38c 62e6c8ff System.Windows.Application.RunInternal(System.Windows.Window) 0040f3b0 62e6c682 System.Windows.Application.Run(System.Windows.Window) 0040f3c0 62e6c30b System.Windows.Application.Run() 0040f3cc 001f00bc MyApplication.App.Main() [C:\code\trunk\MyApplication\obj\Debug\GeneratedInternalTypeHelper.g.cs @ 24] 0040f608 66c421db [GCFrame: 0040f608] EDIT -- not sure if this helps, but the main thread's call stack looks like this: [Managed to Native Transition] > WindowsBase.dll!MS.Win32.UnsafeNativeMethods.GetMessageW(ref System.Windows.Interop.MSG msg, System.Runtime.InteropServices.HandleRef hWnd, int uMsgFilterMin, int uMsgFilterMax) + 0x15 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.GetMessage(ref System.Windows.Interop.MSG msg, System.IntPtr hwnd, int minMessage, int maxMessage) + 0x48 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame = {System.Windows.Threading.DispatcherFrame}) + 0x85 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame frame) + 0x49 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.Run() + 0x4c bytes PresentationFramework.dll!System.Windows.Application.RunDispatcher(object ignore) + 0x17 bytes PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) + 0x6f bytes PresentationFramework.dll!System.Windows.Application.Run(System.Windows.Window window) + 0x26 bytes PresentationFramework.dll!System.Windows.Application.Run() + 0x1b bytes I did a search on it and found some posts related to WPF GUIs hanging, and maybe that'll give me some more clues.

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• How do I learn algorithms?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be lear ning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• Resumable upload from Java client to Grails web application?

  - by dersteps

  After almost 2 workdays of Googling and trying several different possibilities I found throughout the web, I'm asking this question here, hoping that I might finally get an answer. First of all, here's what I want to do: I'm developing a client and a server application with the purpose of exchanging a lot of large files between multiple clients on a single server. The client is developed in pure Java (JDK 1.6), while the web application is done in Grails (2.0.0). As the purpose of the client is to allow users to exchange a lot of large files (usually about 2GB each), I have to implement it in a way, so that the uploads are resumable, i.e. the users are able to stop and resume uploads at any time. Here's what I did so far: I actually managed to do what I wanted to do and stream large files to the server while still being able to pause and resume uploads using raw sockets. I would send a regular request to the server (using Apache's HttpClient library) to get the server to send me a port that was free for me to use, then open a ServerSocket on the server and connect to that particular socket from the client. Here's the problem with that: Actually, there are at least two problems with that: I open those ports myself, so I have to manage open and used ports myself. This is quite error-prone. I actually circumvent Grails' ability to manage a huge amount of (concurrent) connections. Finally, here's what I'm supposed to do now and the problem: As the problems I mentioned above are unacceptable, I am now supposed to use Java's URLConnection/HttpURLConnection classes, while still sticking to Grails. Connecting to the server and sending simple requests is no problem at all, everything worked fine. The problems started when I tried to use the streams (the connection's OutputStream in the client and the request's InputStream in the server). Opening the client's OutputStream and writing data to it is as easy as it gets. But reading from the request's InputStream seems impossible to me, as that stream is always empty, as it seems. Example Code Here's an example of the server side (Groovy controller): def test() { InputStream inStream = request.inputStream if(inStream != null) { int read = 0; byte[] buffer = new byte[4096]; long total = 0; println "Start reading" while((read = inStream.read(buffer)) != -1) { println "Read " + read + " bytes from input stream buffer" //<-- this is NEVER called } println "Reading finished" println "Read a total of " + total + " bytes" // <-- 'total' will always be 0 (zero) } else { println "Input Stream is null" // <-- This is NEVER called } } This is what I did on the client side (Java class): public void connect() { final URL url = new URL("myserveraddress"); final byte[] message = "someMessage".getBytes(); // Any byte[] - will be a file one day HttpURLConnection connection = url.openConnection(); connection.setRequestMethod("GET"); // other methods - same result // Write message DataOutputStream out = new DataOutputStream(connection.getOutputStream()); out.writeBytes(message); out.flush(); out.close(); // Actually connect connection.connect(); // is this placed correctly? // Get response BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream())); String line = null; while((line = in.readLine()) != null) { System.out.println(line); // Prints the whole server response as expected } in.close(); } As I mentioned, the problem is that request.inputStream always yields an empty InputStream, so I am never able to read anything from it (of course). But as that is exactly what I'm trying to do (so I can stream the file to be uploaded to the server, read from the InputStream and save it to a file), this is rather disappointing. I tried different HTTP methods, different data payloads, and also rearranged the code over and over again, but did not seem to be able to solve the problem. What I hope to find I hope to find a solution to my problem, of course. Anything is highly appreciated: hints, code snippets, library suggestions and so on. Maybe I'm even having it all wrong and need to go in a totally different direction. So, how can I implement resumable file uploads for rather large (binary) files from a Java client to a Grails web application without manually opening ports on the server side?

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• Printing out variables in c changes values of variables

  - by George Wilson

  I have an odd problem with some c-programme here. I was getting some wrong values in a matrix I was finding the determinant of and so I started printing variables - yet found that by printing values out the actual values in the code changed. I eventually narrowed it down to one specific printf statement - highlighted in the code below. If I comment out this line then I start getting incorrect values in my determinent calculations, yet by printing it out I get the value out I expect Code below: #include <math.h> #include <stdio.h> #include <stdlib.h> #define NUMBER 15 double determinant_calculation(int size, double array[NUMBER][NUMBER]); int main() { double array[NUMBER][NUMBER], determinant_value; int size; array[0][0]=1; array[0][1]=2; array[0][2]=3; array[1][0]=4; array[1][1]=5; array[1][2]=6; array[2][0]=7; array[2][1]=8; array[2][2]=10; size=3; determinant_value=determinant_calculation(size, array); printf("\n\n\n\n\n\nDeterminant value is %lf \n\n\n\n\n\n", determinant_value); return 0; } double determinant_calculation(int size, double array[NUMBER][NUMBER]) { double determinant_matrix[NUMBER][NUMBER], determinant_value; int x, y, count=0, sign=1, i, j; /*initialises the array*/ for (i=0; i<(NUMBER); i++) { for(j=0; j<(NUMBER); j++) { determinant_matrix[i][j]=0; } } /*does the re-cursion method*/ for (count=0; count<size; count++) { x=0; y=0; for (i=0; i<size; i++) { for(j=0; j<size; j++) { if (i!=0&&j!=count) { determinant_matrix[x][y]=array[i][j]; if (y<(size-2)) { y++; } else { y=0; x++; } } } } //commenting this for loop out changes the values of the code determinent prints -7 when commented out and -3 (expected) when included! for (i=0; i<size; i++) { for(j=0; j<size; j++){ printf("%lf ", determinant_matrix[i][j]); } printf("\n"); } if(size>2) { determinant_value+=sign*(array[0][count]*determinant_calculation(size-1 ,determinant_matrix)); } else { determinant_value+=sign*(array[0][count]*determinant_matrix[0][0]); } sign=-1*sign; } return (determinant_value); } I know its not the prettiest (or best way) of doing what I'm doing with this code but it's what I've been given - so can't make huge changes. I don't suppose anyone could explain why printing out the variables can actually change the values? or how to fix it because ideally i don't want to!!

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• Is it normal that .Net combobox postback always contains data items?

  - by BlueFox

  I have a dynamically populated ComponentArt:ComboBox with Autopostback property set to true. So every time the selection changes, a postback to server would be fired. Everything seems to work fine except that the lists of all available items are also posted back to the server. from Firebug: ComboBox1_Data %3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3E150%20Mile%20House%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAach%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAachen%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAaheim%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAakrehamn%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAalbeke%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAalen%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAalst%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAalter%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3E%C3%84%C3%A4nekoski%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarau%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarberg%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarbergen%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarburg%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarebakken%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarschot%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAarsele%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAartrijke%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAartselaar%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3Cc%3E%3Cr%3E%3Cc%3E%3Cr%3E%3Cc%3EText%3C%2Fc%3E%3Cc%3EAavasaksa%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E%3C%2Fc%3E%3C%2Fr%3E ComboBox1_Input Aalst ComboBox1_SelectedIndex 7 As most my clients are using slow connections, this amount of postback has a huge impact on their user experience. Since I'm storing the viewstates in session already, there's really no need for any of the component to restore states from the client. So I'm wondering if this is normal for ComponentArt:ComboBox to do this and not other controls, or this is the normal way of doing things?

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• CSS optimization - extra classes in dom or preprocessor-repetitive styling in css file?

  - by anna.mi

  I'm starting on a fairly large project and I'm considering the option of using LESS for pre-processing my css. the useful thing about LESS is that you can define a mixin that contains for example: .border-radius(@radius) { -webkit-border-radius: @radius; -moz-border-radius: @radius; -o-border-radius: @radius; -ms-border-radius: @radius; border-radius: @radius; } and then use it in a class declaration as .rounded-div { .border-radius(10px); } to get the outputted css as: .rounded-div { -webkit-border-radius: 10px; -moz-border-radius: 10px; -o-border-radius: 10px; -ms-border-radius: 10px; border-radius: 10px; } this is extremely useful in the case of browser prefixes. However this same concept could be used to encapsulate commonly-used css, for example: .column-container { overflow: hidden; display: block; width: 100%; } .column(@width) { float: left; width: @width; } and then use this mixin whenever i need columns in my design: .my-column-outer { .column-container(); background: red; } .my-column-inner { .column(50%); font-color: yellow; } (of course, using the preprocessor we could easily expand this to be much more useful, eg. pass the number of columns and the container width as variables and have LESS determine the width of each column depending on the number of columns and container width!) the problem with this is that when compliled, my final css file would have 100 such declarations, copy&pasted, making the file huge and bloated and repetitive. The alternative to this would be to use a grid system which has predefined classes for each column-layout option, eg .c-50 ( with a "float: left; width:50%;" definition ), .c-33, .c-25 to accomodate for a 2-column, 3-column and 4-column layout and then use these classes to my dom. i really mislike the idea of the extra classes, from experience it results to bloated dom (creating extra divs just to attach the grid classes to). Also the most basic tutorial for html/css would tell you that the dom should be separated from the styling - grid classes are styling related! to me, its the same as attaching a "border-radius-10" class to the .rounded-div example above! on the other hand, the large css file that would result from the repetitive code is also a disadvantage so i guess my question is, which one would you recommend? and which do you use? and, which solution is best for optimization? apart from the larger file size, has there even been any research on whether browser renders multiple classes faster than a large css file, or the other way round? tnx! i'd love to hear your opinion!

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• a friendly elaboratation on how iceweasel misses as recent request was discovered in post tut

  - by v3x3n

  I would like to specify what you asked about in how iceweasel misses on in hopes that you are interested in considering the answer to be valid considering the package should run efficient to a novice user especially when getting a first impression on a new software, browser, or package they are given by default. First let me say that I am very grateful for all debian has and continues to do for its user base and I am not complaining, only hoping that in mentioning such it will eventually aid in improving the disappointing experience iceweasel gave me in multiple ways right from the start of using it. I am sure tremendous amounts of hard work went into making it work as well as it does, and tremendous effort continues to go into IW like the rest of the package and distros such as this... Having said that, I do aim to keep my examples simple as possible but also explained in enough detail as to not leave out important info to get a full idea of my issue... (Thanks for understanding if I sound novice to debian, I am but continue to learn and advance by trial and error each day, and of course the wonderful help from all the great minds available here and there)... Well, my bone to pick (unfortunately as I disdain being a complainer when so much has been done for us, the end user) with IW is mainly 3 immediately noticed problems in offering me a smooth test drive (completely normal browsing conduct of your average user, I should indicate) as soon as I started out a task using IW (heading directly to google images and searched for a few web sized images, then saved a few (no more than 800 to 900 in dimensions, typically a normal procedure I would imagine) I experienced a horrendous reoccurring freeze and lag time that almost left me to kill the process more than once on each attempt and continued to compound so that by a few attempts later, even 1 single image save locked up the entire browser, ultimately giving up on my procedure in its simplicity with a bit of aggravation, if there was something I had done wrong on my end pre-attempt or during installation. Secondly, visiting video player sites in this case youtube will not allow for any video feed to play whatsoever and again, experienced a slight freezing that eventually dissipated as long as I didn't attempt to press play or reload another video trial... Very annoying and possibly related to my first issue (which could rely on my own lack of knowledge in setup config, but that troubles me if so).... Lastly as another user has stated already, in which brought you to ask them what exactly seemed to be the problem in the first place is also my final straw that broke the weasel's back, leading me here to find a solution to a updated version of firefox... being that iceweasel (an apparent build of firefox 17.x.x) leaving the user to find themselves out of luck when installing their favorite or much useful add-ons or plugins that aid their task or normal usage online.... As the other user clearly stated... there is almost zero options and barely any luck to find compatible plugins with such an outdated version still being used... I can only imagine if as a novoice or standard user to linux... and beginner to debian (which I am all for btw!) if I am discovering major conductivity issues which hinder normal user conduct right off the bat... that there is probably a bundle or more of security vulnerabilities that would unravel to me if I continued to give mr Hommey's package any further attention, or interest in continuing to use... This is a deal breaker on any account, unless all 3 of these issues stated are due to a very n00berish setting or lack thereof (which if that is the case, such was not properly stated for beginner in any place available by following installation tutorials such as LVM installers, which I felt lacked a clear understanding to someone who is trying to learn why and how, rather than, a fix to a potentially broken out of box installation... I really think that is irrelevant in any case however, as there is much step by step support regarding that kind of thing, just saying... its very challenging, along side a job to keep deadlines on, and the need to learn a better and more costomizible system, that was not as popularized when I became a dev via windows (OK OK I know thats a huge mistake and now I am way off original topic but anyway) Thanks very much for taking the time to read over this, and I hope it honestly gives you a few good and valid reasons for users wanting and seeking a way to get around iceweasel altogether... Finally, if I am missing something vital that renders all I've stated invalid or useless, please feel free to shove that elephant in the room my direction! Thanks for all you do, as I am sure it is very useful and dedicated, being you are a debian maintainer, and super user! Much love for intelligence, freedom and sharing the secrets of the web! May it remain unregulated and a good place to grow and learn for generations to come! Stay true! Take care now! -v3x (v3x @ gmx .com)

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• Please clarify how create/update happens against child entities of an aggregate root

  - by christian

  After much reading and thinking as I begin to get my head wrapped around DDD, I am a bit confused about the best practices for dealing with complex hierarchies under an aggregate root. I think this is a FAQ but after reading countless examples and discussions, no one is quite talking about the issue I'm seeing. If I am aligned with the DDD thinking, entities below the aggregate root should be immutable. This is the crux of my trouble, so if that isn't correct, that is why I'm lost. Here is a fabricated example...hope it holds enough water to discuss. Consider an automobile insurance policy (I'm not in insurance, but this matches the language I hear when on the phone w/ my insurance company). Policy is clearly an entity. Within the policy, let's say we have Auto. Auto, for the sake of this example, only exists within a policy (maybe you could transfer an Auto to another policy, so this is potential for an aggregate as well, which changes Policy...but assume it simpler than that for now). Since an Auto cannot exist without a Policy, I think it should be an Entity but not a root. So Policy in this case is an aggregate root. Now, to create a Policy, let's assume it has to have at least one auto. This is where I get frustrated. Assume Auto is fairly complex, including many fields and maybe a child for where it is garaged (a Location). If I understand correctly, a "create Policy" constructor/factory would have to take as input an Auto or be restricted via a builder to not be created without this Auto. And the Auto's creation, since it is an entity, can't be done beforehand (because it is immutable? maybe this is just an incorrect interpretation). So you don't get to say new Auto and then setX, setY, add(Z). If Auto is more than somewhat trivial, you end up having to build a huge hierarchy of builders and such to try to manage creating an Auto within the context of the Policy. One more twist to this is later, after the Policy is created and one wishes to add another Auto...or update an existing Auto. Clearly, the Policy controls this...fine...but Policy.addAuto() won't quite fly because one can't just pass in a new Auto (right!?). Examples say things like Policy.addAuto(VIN, make, model, etc.) but are all so simple that that looks reasonable. But if this factory method approach falls apart with too many parameters (the entire Auto interface, conceivably) I need a solution. From that point in my thinking, I'm realizing that having a transient reference to an entity is OK. So, maybe it is fine to have a entity created outside of its parent within the aggregate in a transient environment, so maybe it is OK to say something like: auto = AutoFactory.createAuto(); auto.setX auto.setY or if sticking to immutability, AutoBuilder.new().setX().setY().build() and then have it get sorted out when you say Policy.addAuto(auto) This insurance example gets more interesting if you add Events, such as an Accident with its PolicyReports or RepairEstimates...some value objects but most entities that are all really meaningless outside the policy...at least for my simple example. The lifecycle of Policy with its growing hierarchy over time seems the fundamental picture I must draw before really starting to dig in...and it is more the factory concept or how the child entities get built/attached to an aggregate root that I haven't seen a solid example of. I think I'm close. Hope this is clear and not just a repeat FAQ that has answers all over the place.

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• count specific things within a code in c++

  - by shap

  can anyone help me make this more generalised and more pro? #include <fstream> #include <iostream> #include <string> #include <vector> using namespace std; int main() { // open text file for input: string file_name; cout << "please enter file name: "; cin >> file_name; // associate the input file stream with a text file ifstream infile(file_name.c_str()); // error checking for a valid filename if ( !infile ) { cerr << "Unable to open file " << file_name << " -- quitting!\n"; return( -1 ); } else cout << "\n"; // some data structures to perform the function vector<string> lines_of_text; string textline; // read in text file, line by while (getline( infile, textline, '\n' )) { // add the new element to the vector lines_of_text.push_back( textline ); // print the 'back' vector element - see the STL documentation cout << lines_of_text.back() << "\n"; } cout<<"OUTPUT BEGINS HERE: "<<endl<<endl; cout<<"the total capacity of vector: lines_of_text is: "<<lines_of_text.capacity()<<endl; int PLOC = (lines_of_text.size()+1); int numbComments =0; int numbClasses =0; cout<<"\nThe total number of physical lines of code is: "<<PLOC<<endl; for (int i=0; i<(PLOC-1); i++) //reads through each part of the vector string line-by-line and triggers if the //it registers the "//" which will output a number lower than 100 (since no line is 100 char long and if the function does not //register that character within the string, it outputs a public status constant that is found in the class string and has a huge value //alot more than 100. { string temp(lines_of_text [i]); if (temp.find("//")<100) numbComments +=1; } cout<<"The total number of comment lines is: "<<numbComments<<endl; for (int j=0; j<(PLOC-1); j++) { string temp(lines_of_text [j]); if (temp.find("};")<100) numbClasses +=1; } cout<<"The total number of classes is: "<<numbClasses<<endl;

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• Override `drop` for a custom sequence

  - by Bruno Reis

  In short: in Clojure, is there a way to redefine a function from the standard sequence API (which is not defined on any interface like ISeq, IndexedSeq, etc) on a custom sequence type I wrote? 1. Huge data files I have big files in the following format: A long (8 bytes) containing the number n of entries n entries, each one being composed of 3 longs (ie, 24 bytes) 2. Custom sequence I want to have a sequence on these entries. Since I cannot usually hold all the data in memory at once, and I want fast sequential access on it, I wrote a class similar to the following: (deftype DataSeq [id ^long cnt ^long i cached-seq] clojure.lang.IndexedSeq (index [_] i) (count [_] (- cnt i)) (seq [this] this) (first [_] (first cached-seq)) (more [this] (if-let [s (next this)] s '())) (next [_] (if (not= (inc i) cnt) (if (next cached-seq) (DataSeq. id cnt (inc i) (next cached-seq)) (DataSeq. id cnt (inc i) (with-open [f (open-data-file id)] ; open a memory mapped byte array on the file ; seek to the exact position to begin reading ; decide on an optimal amount of data to read ; eagerly read and return that amount of data )))))) The main idea is to read ahead a bunch of entries in a list and then consume from that list. Whenever the cache is completely consumed, if there are remaining entries, they are read from the file in a new cache list. Simple as that. To create an instance of such a sequence, I use a very simple function like: (defn ^DataSeq load-data [id] (next (DataSeq. id (count-entries id) -1 []))) ; count-entries is a trivial "open file and read a long" memoized As you can see, the format of the data allowed me to implement count in very simply and efficiently. 3. drop could be O(1) In the same spirit, I'd like to reimplement drop. The format of these data files allows me to reimplement drop in O(1) (instead of the standard O(n)), as follows: if dropping less then the remaining cached items, just drop the same amount from the cache and done; if dropping more than cnt, then just return the empty list. otherwise, just figure out the position in the data file, jump right into that position, and read data from there. My difficulty is that drop is not implemented in the same way as count, first, seq, etc. The latter functions call a similarly named static method in RT which, in turn, calls my implementation above, while the former, drop, does not check if the instance of the sequence it is being called on provides a custom implementation. Obviously, I could provide a function named anything but drop that does exactly what I want, but that would force other people (including my future self) to remember to use it instead of drop every single time, which sucks. So, the question is: is it possible to override the default behaviour of drop? 4. A workaround (I dislike) While writing this question, I've just figured out a possible workaround: make the reading even lazier. The custom sequence would just keep an index and postpone the reading operation, that would happen only when first was called. The problem is that I'd need some mutable state: the first call to first would cause some data to be read into a cache, all the subsequent calls would return data from this cache. There would be a similar logic on next: if there's a cache, just next it; otherwise, don't bother populating it -- it will be done when first is called again. This would avoid unnecessary disk reads. However, this is still less than optimal -- it is still O(n), and it could easily be O(1). Anyways, I don't like this workaround, and my question is still open. Any thoughts? Thanks.

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• How can I remove this query from within a loop?

  - by Chris

  I am currently designing a forum as a personal project. One of the recurring issues I've come across is database queries in loops. I've managed to avoid doing that so far by using table joins or caching of data in arrays for later use. Right now though I've come across a situation where I'm not sure how I can write the code in such a way that I can use either of those methods easily. However I'd still prefer to do at most 2 queries for this operation rather than 1 + 1 per group of forums, which so far has resulted in 5 per page. So while 5 isn't a huge number (though it will increase for each forum group I add) it's the principle that's important to me here, I do NOT want to write queries in loops What I'm doing is displaying forum index groupings (eg admin forums, user forums etc) and then each forum within that group on a single page index, it's the combination of both in one page that's causing me issue. If it had just been a single group per page, I'd use a table join and problem solved. But if I use a table join here, although I can potentially get all the data I need it'll be in one mass of results and it needs displaying properly. Here's the code (I've removed some of the html for clarity) <?php $sql= "select * from forum_groups"; //query 1 $result1 = $database->query($sql); while($group = mysql_fetch_assoc($result1)) //first loop {?> <table class="threads"> <tr> <td class="forumgroupheader"> <?php echo $group['group_name']; ?> </td> </tr> <tr> <td class="forumgroupheader2"> <?php echo $group['group_desc']; ?> </td> </tr> </table> <table> <tr> <th class="thforum"> Forum Name</th> <th class="thforum"> Forum Decsription</th> <th class="thforum"> Last Post </th> <tr> <?php $group_id = $group['id']; $sql = "SELECT forums.id, forums.forum_group_id, forums.forum_name, forums.forum_desc, forums.visible_rank, forums.locked, forums.lock_rank, forums.topics, forums.posts, forums.last_post, forums.last_post_id, users.username FROM forums LEFT JOIN users on forums.last_post_id=users.id WHERE forum_group_id='{$group_id}'"; //query 2 $result2 = $database->query($sql); while($forum = mysql_fetch_assoc($result2)) //second loop {?> So how can I either a) write the SQL in such a way as to remove the second query from inside the loop or b) combine the results in an array either way I need to be able to access the data as an when so I can format it properly for the page output, ie within the loops still.

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