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  • Boost timed_wait leap seconds problem

    - by Isac
    Hi, I am using the timed_wait from boost C++ library and I am getting a problem with leap seconds. Here is a quick example from boosts documentation: boost::system_time const timeout=boost::get_system_time() + boost::posix_time::milliseconds(500); extern bool done; extern boost::mutex m; extern boost::condition_variable cond; boost::unique_lock<boost::mutex> lk(m); while(!done) { if(!cond.timed_wait(lk,timeout)) { throw "timed out"; } } The timed_wait function is returning 24 seconds earlier than it should. 24 seconds is the current amount of leap seconds in UTC. So, boost is widely used but I could not find any info about this particular problem. Has anyone else experienced this problem? What are the possible causes and solutions? Notes: I am using boost 1.38 on a linux system. I've heard that this problem doesn't happen on MacOS.

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  • how to parse a Date string to java.Date

    - by hguser
    Hi: I have a date string and I wang to parse it to normal date use the java Date API,the following is my code: public static void main(String[] args) { String date="2010-10-02T12:23:23Z"; String pattern="yyyy-MM-ddThh:mm:ssZ"; SimpleDateFormat sdf=new SimpleDateFormat(pattern); try { Date d=sdf.parse(date); System.out.println(d.getYear()); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } } However I got a exception:java.lang.IllegalArgumentException: Illegal pattern character 'T' So I wonder if i have to split the string and parse it manually? BTW, I have tried to add a single quote character on either side of the T: String pattern="yyyy-MM-dd'T'hh:mm:ssZ"; It also does not work.

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  • How do NTP Servers Manage to Stay so Accurate?

    - by Akemi Iwaya
    Many of us have had the occasional problem with our computers and other devices retaining accurate time settings, but a quick sync with an NTP server makes all well again. But if our own devices can lose accuracy, how do NTP servers manage to stay so accurate? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. Photo courtesy of LEOL30 (Flickr). The Question SuperUser reader Frank Thornton wants to know how NTP servers are able to remain so accurate: I have noticed that on my servers and other machines, the clocks always drift so that they have to sync up to remain accurate. How do the NTP server clocks keep from drifting and always remain so accurate? How do the NTP servers manage to remain so accurate? The Answer SuperUser contributor Michael Kjorling has the answer for us: NTP servers rely on highly accurate clocks for precision timekeeping. A common time source for central NTP servers are atomic clocks, or GPS receivers (remember that GPS satellites have atomic clocks onboard). These clocks are defined as accurate since they provide a highly exact time reference. There is nothing magical about GPS or atomic clocks that make them tell you exactly what time it is. Because of how atomic clocks work, they are simply very good at, having once been told what time it is, keeping accurate time (since the second is defined in terms of atomic effects). In fact, it is worth noting that GPS time is distinct from the UTC that we are more used to seeing. These atomic clocks are in turn synchronized against International Atomic Time or TAI in order to not only accurately tell the passage of time, but also the time. Once you have an exact time on one system connected to a network like the Internet, it is a matter of protocol engineering enabling transfer of precise times between hosts over an unreliable network. In this regard a Stratum 2 (or farther from the actual time source) NTP server is no different from your desktop system syncing against a set of NTP servers. By the time you have a few accurate times (as obtained from NTP servers or elsewhere) and know the rate of advancement of your local clock (which is easy to determine), you can calculate your local clock’s drift rate relative to the “believed accurate” passage of time. Once locked in, this value can then be used to continuously adjust the local clock to make it report values very close to the accurate passage of time, even if the local real-time clock itself is highly inaccurate. As long as your local clock is not highly erratic, this should allow keeping accurate time for some time even if your upstream time source becomes unavailable for any reason. Some NTP client implementations (probably most ntpd daemon or system service implementations) do this, and others (like ntpd’s companion ntpdate which simply sets the clock once) do not. This is commonly referred to as a drift file because it persistently stores a measure of clock drift, but strictly speaking it does not have to be stored as a specific file on disk. In NTP, Stratum 0 is by definition an accurate time source. Stratum 1 is a system that uses a Stratum 0 time source as its time source (and is thus slightly less accurate than the Stratum 0 time source). Stratum 2 again is slightly less accurate than Stratum 1 because it is syncing its time against the Stratum 1 source and so on. In practice, this loss of accuracy is so small that it is completely negligible in all but the most extreme of cases. Have something to add to the explanation? Sound off in the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.

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  • JSON Date coming through as Today's date?

    - by Liam
    I'm trying to convert a JSON date to a dd/mm/yyyy format, which I'm managing to do semi-successfully. The problem I'm encountering is that the date from the record in the DB is for example, 2009-06-29 which is returning the usual JSON /Date(1246230000000)/, however, when I try and turn it into the previously mention dd/mm/yyyy format, it's coming through as today's date. The code I'm using to try and do this is: $('input#EmployeeName').result(function(event, data, formatted) { $('#StartDate').html(formatJSONDate(Date(!data ? '' : data.StartDate))); }); function formatJSONDate(jsonDate) { var newDate = dateFormat(jsonDate, "dd/mm/yyyy"); return newDate; } I'm using JavaScript Date Format to try and run the function. Any help is greatly appreciated.

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  • Date object javascript

    - by Isis
    Hello. var date = new Date();//Mon Mar 15 2010 12:40:05 GMT+0300 (MSK) var omg = date.getDate() + 19;// 34 date.setDate(omg); document.write(date.toLocaleString()); //Sat 03 Apr 2010 12:43:00 PM MSK How do I echo the values 3 (ie: day of month), 4 (April) and the current year? alert(day); // Need 3 alert(month); // Need 4 Thank you

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  • number of months between two dates - using boost's date

    - by MartinP
    I've used boost::gregorian::date a bit now. I can see that there are the related months & years & weeks duration types. I can see how to use known durations to advance a given date. Qu: But how can I get the difference between two dates in months (or years or weeks) ? I was hoping to find a function like: template<typename DURATION> DURATION date_diff<DURATION>(const date& d1,const date& d2); There would need to be some handling of rounding too.

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  • how can I select data from MySQL based on date (unix time record)

    - by bn
    I have a record of data with unix time date in it i want to select the row based on the date/month/year only (not with time) currently Im using something like this select * from tablename where date > '$today' and date < '$tomorow' LIMIT 1; how ever this is not that accurate if the $today and $tomorrow have different time (but same date) is there any better way to do this?

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  • Populate google.visualization.DataTable for a AnnotatedTimeLine using JSON

    - by Lucifer
    Hi I have a HttpHandler which returns some JSON in (i think) the correct format for a google.visualization.DataTable, but the AnnotatedTimeLine fails to work? This is the JSON returned by the Handler: {cols: [{id: 'DATE', label: 'Date', type: 'date'}, {id: 'KEYWORD51', label: 'vw cheltenham', type: 'number'}, {id: 'KEYWORD52', label: 'volkswagen cheltenham', type: 'number'}, {id: 'KEYWORD61', label: 'vw dealer cheltenham', type: 'number'}], rows: [{c: [{v: new Date(2010, 3, 13)}, {v: 20}, {v: 1}, {v: 2}]}, {c: [{v: new Date(2010, 3, 14)}, {v: 19}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 15)}, {v: 19}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 16)}, {v: 18}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 17)}, {v: 17}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 18)}, {v: 17}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 19)}, {v: 12}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 20)}, {v: 13}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 21)}, {v: 11}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 22)}, {v: 10}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 23)}, {v: 10}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 24)}, {v: 8}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 25)}, {v: 6}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 26)}, {v: 6}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 27)}, {v: 5}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 28)}, {v: 4}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 29)}, {v: 4}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 3, 30)}, {v: 2}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 1)}, {v: 2}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 2)}, {v: 1}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 3)}, {v: 2}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 4)}, {v: 0}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 5)}, {v: 0}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 6)}, {v: 0}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 4, 7)}, {v: 0}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 4, 8)}, {v: 0}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 4, 9)}, {v: 0}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 4, 10)}, {v: 0}, {v: 0}, {v: 0}]}, {c: [{v: new Date(2010, 4, 11)}, {v: 0}, {v: 1}, {v: 1}]}, {c: [{v: new Date(2010, 4, 12)}, {v: 2}, {v: 1}, {v: 1}]}]} This is the Javascript, I used JQuery to get the JSON, have also tried $.getJSON() google.load('visualization', '1', { 'packages': ['annotatedtimeline'] }); google.setOnLoadCallback(loadGraph); function loadGraph() { $.get("/GraphDataHandler.axd", function(response) { drawGraph(response); }); } function drawGraph(response) { var visualization = new google.visualization.AnnotatedTimeLine(document.getElementById('chart_div')); var data = new google.visualization.DataTable(response, 0.6); visualization.draw(data, { title: 'Rankings', titleX: 'Date', titleY: 'Position', displayAnnotations: false, allowRedraw: true }); } But, if I write the same JSON to the page like below it works fine!? <script type="text/javascript"> //<![CDATA[ var gData = {cols: [{id: 'DATE', label: 'Date', type: 'date'}, {id: 'KEYWORD51', label: 'vw cheltenham', type: 'number'}], rows: [{c: [{v: new Date(2010, 3, 13)}, {v: 20}]}, {c: [{v: new Date(2010, 3, 14)}, {v: 19}]}, {c: [{v: new Date(2010, 3, 15)}, {v: 19}]}, {c: [{v: new Date(2010, 3, 16)}, {v: 18}]}, {c: [{v: new Date(2010, 3, 17)}, {v: 17}]}, {c: [{v: new Date(2010, 3, 18)}, {v: 17}]}, {c: [{v: new Date(2010, 3, 19)}, {v: 12}]}, {c: [{v: new Date(2010, 3, 20)}, {v: 13}]}, {c: [{v: new Date(2010, 3, 21)}, {v: 11}]}, {c: [{v: new Date(2010, 3, 22)}, {v: 10}]}, {c: [{v: new Date(2010, 3, 23)}, {v: 10}]}, {c: [{v: new Date(2010, 3, 24)}, {v: 8}]}, {c: [{v: new Date(2010, 3, 25)}, {v: 6}]}, {c: [{v: new Date(2010, 3, 26)}, {v: 6}]}, {c: [{v: new Date(2010, 3, 27)}, {v: 5}]}, {c: [{v: new Date(2010, 3, 28)}, {v: 4}]}, {c: [{v: new Date(2010, 3, 29)}, {v: 4}]}, {c: [{v: new Date(2010, 3, 30)}, {v: 2}]}, {c: [{v: new Date(2010, 4, 1)}, {v: 2}]}, {c: [{v: new Date(2010, 4, 2)}, {v: 1}]}, {c: [{v: new Date(2010, 4, 3)}, {v: 2}]}, {c: [{v: new Date(2010, 4, 4)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 5)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 6)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 7)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 8)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 9)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 10)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 11)}, {v: 0}]}, {c: [{v: new Date(2010, 4, 12)}, {v: 2}]}]}; //]]> </script> Please advise how I can get it to work correctly using a the JSON calls? Thanks

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  • Simplest way to get current time in current timezone using boost::date_time ?

    - by timday
    If I do date +%H-%M-%S on the commandline (Debian/Lenny), I get a user-friendly (not UTC, not DST-less, the time a normal person has on their wristwatch) time printed. What's the simplest way to obtain the same thing with boost::date_time ? If I do this: std::ostringstream msg; boost::local_time::local_date_time t = boost::local_time::local_sec_clock::local_time( boost::local_time::time_zone_ptr() ); boost::local_time::local_time_facet* lf( new boost::local_time::local_time_facet("%H-%M-%S") ); msg.imbue(std::locale(msg.getloc(),lf)); msg << t; Then msg.str() is an hour earlier than the time I want to see. I'm not sure whether this is because it's showing UTC or local timezone time without a DST correction (I'm in the UK). What's the simplest way to modify the above to yield the DST corrected local timezone time ? I have an idea it involves boost::date_time:: c_local_adjustor but can't figure it out from the examples.

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  • Accomplishing boost::shared_from_this() in constructor via boost::shared_from_raw(this)

    - by Kyle
    Googling and poking around the boost code, it appears that it's now possible to construct a shared_ptr to this in a constructor, by inheriting from enable_shared_from_raw and calling shared_from_raw(this) Is there any documentation or examples of this? I'm finding nothing with google. Why am I not finding any useful buzz on this on google? I would have thought using shared_from_this in a constructor would be a hot/desirable item. Should I be inheriting from both enable_shared_from_raw and enable_shared_from_this, and restricting my usage of enable_shared_from_raw when I have to? If so, why? Is there a performance hit with shared_from_raw?

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  • Win32 reset event like synchronization class with boost C++

    - by fgungor
    I need some mechanism reminiscent of Win32 reset events that I can check via functions having the same semantics with WaitForSingleObject() and WaitForMultipleObjects() (Only need the ..SingleObject() version for the moment) . But I am targeting multiple platforms so all I have is boost::threads (AFAIK) . I came up with the following class and wanted to ask about the potential problems and whether it is up to the task or not. Thanks in advance. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) return; cond_var.wait(LOCK); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); bool ret = cond_var.timed_wait(LOCK, dur) || flag; if (auto_reset && ret) flag = false; return ret; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } }; Example usage; reset_event terminate_thread; void fn_thread() { while(!terminate_thread.wait(boost::posix_time::milliseconds(10))) { std::cout << "working..." << std::endl; boost::this_thread::sleep(boost::posix_time::milliseconds(1000)); } std::cout << "thread terminated" << std::endl; } int main() { boost::thread worker(fn_thread); boost::this_thread::sleep(boost::posix_time::seconds(1)); terminate_thread.set(); worker.join(); return 0; } EDIT I have fixed the code according to Michael Burr's suggestions. My "very simple" tests indicate no problems. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: explicit reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return; } do { cond_var.wait(LOCK); } while(!flag); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return true; } bool ret = cond_var.timed_wait(LOCK, dur); if (ret && flag) { if (auto_reset) flag = false; return true; } return false; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } };

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  • Composing adaptors in Boost::range

    - by bruno nery
    I started playing with Boost::Range in order to have a pipeline of lazy transforms in C++]1. My problem now is how to split a pipeline in smaller parts. Suppose I have: int main(){ auto map = boost::adaptors::transformed; // shorten the name auto sink = generate(1) | map([](int x){ return 2*x; }) | map([](int x){ return x+1; }) | map([](int x){ return 3*x; }); for(auto i : sink) std::cout << i << "\n"; } And I want to replace the first two maps with a magic_transform, i.e.: int main(){ auto map = boost::adaptors::transformed; // shorten the name auto sink = generate(1) | magic_transform() | map([](int x){ return 3*x; }); for(auto i : sink) std::cout << i << "\n"; } How would one write magic_transform? I looked up Boost::Range's documentation, but I can't get a good grasp of it.

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  • Compare two variant with boost static_visitor

    - by Zozzzzz
    I started to use the boost library a few days ago so my question is maybe trivial. I want to compare two same type variants with a static_visitor. I tried the following, but it don't want to compile. struct compare:public boost::static_visitor<bool> { bool operator()(int& a, int& b) const { return a<b; } bool operator()(double& a, double& b) const { return a<b; } }; int main() { boost::variant<double, int > v1, v2; v1 = 3.14; v2 = 5.25; compare vis; bool b = boost::apply_visitor(vis, v1,v2); cout<<b; return 0; } Thank you for any help or suggestion!

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  • How do I get the current date according to an NTP server without setting it locally?

    - by Zac B
    I want to get the current date and time according to a remote NTP server, using Linux. I don't want to change the local time as a result; I just want to get the remote date, adjusted for the local time zone, printed out. The date returned must comply with the following criteria: It needs to be reasonably accurate. It needs to be adjusted for the timezone on the local system making the request. It needs to be formatted in an easily-readable or interpretable way (standard date format, or seconds since epoch). What I've Tried: I can call ntpdate -q my.ntp.server and get the offset between the local time and the server's time, but that doesn't return the date according to the NTP server; it just returns the offset and the local date. Is there some easy way/command I can use to say: "Print out the date according to a given NTP server, adjusted for my current timezone"?

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  • Using boost locks for RAII access to a semaphore

    - by dan
    Suppose I write a C++ semaphore class with an interface that models the boost Lockable concept (i.e. lock(); unlock(); try_lock(); etc.). Is it safe/recommended to use boost locks for RAII access to such an object? In other words, do boost locks (and/or other related parts of the boost thread library) assume that the Lockable concept will only be modeled by mutex-like objects which are locked and unlocked from the same thread? My guess is that it should be OK to use a semaphore as a model for Lockable. I've browsed through some of the boost source and it "seems" OK. The locks don't appear to store explicit references to this_thread or anything like that. Moreover, the Lockable concept doesn't have any function like whichThreadOwnsMe(). It also looks like I should even be able to pass a boost::unique_lock<MySemaphore> reference to boost::condition_variable_any::wait. However, the documentation is not explicitly clear about the requirements. To illustrate what I mean, consider a bare-bones binary semaphore class along these lines: class MySemaphore{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } Now suppose that somewhere, either on an object or globally, I have MySemaphore sem; I want to lock and unlock it using RAII. Also I want to be able to "pass" ownership of the lock from one thread to another. For example, in one thread I execute void doTask() { boost::unique_lock<MySemaphore> lock(sem); doSomeWorkWithSharedObject(); signalToSecondThread(); waitForSignalAck(); lock.release(); } While another thread is executing something like { waitForSignalFromFirstThread(); ackSignal(); boost::unique_lock<MySemaphore>(sem,boost::adopt_lock_t()); doMoreWorkWithSameSharedObject(); } The reason I am doing this is that I don't want anyone else to be able to get the lock on sem in between the time that the first thread executes doSomeWorkWithSharedObject() and the time the second executes doMoreWorkWithSameSharedObject(). Basically, I'm splitting one task into two parts. And the reason I'm splitting the task up is because (1) I want the first part of the task to get started as soon as possible, (2) I want to guarantee that the first part is complete before doTask() returns, and (3) I want the second, more time-consuming part of the task to be completed by another thread, possibly chosen from a pool of slave threads that are waiting around to finish tasks that have been started by master threads. NOTE: I recently posted this same question (sort of) here http://stackoverflow.com/questions/2754884/unlocking-a-mutex-from-a-different-thread-c but I confused mutexes with semaphores, and so the question about using boost locks didn't really get addressed.

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  • Boost::Interprocess Container Container Resizing No Default Constructor

    - by CuppM
    Hi, After combing through the Boost::Interprocess documentation and Google searches, I think I've found the reason/workaround to my issue. Everything I've found, as I understand it, seems to be hinting at this, but doesn't come out and say "do this because...". But if anyone can verify this I would appreciate it. I'm writing a series of classes that represent a large lookup of information that is stored in memory for fast performance in a parallelized application. Because of the size of data and multiple processes that run at a time on one machine, we're using Boost::Interprocess for shared memory to have a single copy of the structures. I looked at the Boost::Interprocess documentation and examples, and they typedef classes for shared memory strings, string vectors, int vector vectors, etc. And when they "use" them in their examples, they just construct them passing the allocator and maybe insert one item that they've constructed elsewhere. Like on this page: http://www.boost.org/doc/libs/1_42_0/doc/html/interprocess/allocators_containers.html So following their examples, I created a header file with typedefs for shared memory classes: namespace shm { namespace bip = boost::interprocess; // General/Utility Types typedef bip::managed_shared_memory::segment_manager segment_manager_t; typedef bip::allocator<void, segment_manager_t> void_allocator; // Integer Types typedef bip::allocator<int, segment_manager_t> int_allocator; typedef bip::vector<int, int_allocator> int_vector; // String Types typedef bip::allocator<char, segment_manager_t> char_allocator; typedef bip::basic_string<char, std::char_traits<char>, char_allocator> string; typedef bip::allocator<string, segment_manager_t> string_allocator; typedef bip::vector<string, string_allocator> string_vector; typedef bip::allocator<string_vector, segment_manager_t> string_vector_allocator; typedef bip::vector<string_vector, string_vector_allocator> string_vector_vector; } Then for one of my lookup table classes, it's defined something like this: class Details { public: Details(const shm::void_allocator & alloc) : m_Ids(alloc), m_Labels(alloc), m_Values(alloc) { } ~Details() {} int Read(BinaryReader & br); private: shm::int_vector m_Ids; shm::string_vector m_Labels; shm::string_vector_vector m_Values; }; int Details::Read(BinaryReader & br) { int num = br.ReadInt(); m_Ids.resize(num); m_Labels.resize(num); m_Values.resize(num); for (int i = 0; i < num; i++) { m_Ids[i] = br.ReadInt(); m_Labels[i] = br.ReadString().c_str(); int count = br.ReadInt(); m_Value[i].resize(count); for (int j = 0; j < count; j++) { m_Value[i][j] = br.ReadString().c_str(); } } } But when I compile it, I get the error: 'boost::interprocess::allocator<T,SegmentManager>::allocator' : no appropriate default constructor available And it's due to the resize() calls on the vector objects. Because the allocator types do not have a empty constructor (they take a const segment_manager_t &) and it's trying to create a default object for each location. So in order for it to work, I have to get an allocator object and pass a default value object on resize. Like this: int Details::Read(BinaryReader & br) { shm::void_allocator alloc(m_Ids.get_allocator()); int num = br.ReadInt(); m_Ids.resize(num); m_Labels.resize(num, shm::string(alloc)); m_Values.resize(num, shm::string_vector(alloc)); for (int i = 0; i < num; i++) { m_Ids[i] = br.ReadInt(); m_Labels[i] = br.ReadString().c_str(); int count = br.ReadInt(); m_Value[i].resize(count, shm::string(alloc)); for (int j = 0; j < count; j++) { m_Value[i][j] = br.ReadString().c_str(); } } } Is this the best/correct way of doing it? Or am I missing something. Thanks!

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  • boost::program_options bug or feature?

    - by Dmitriy
    Very simple example: #include <string> #include <boost/program_options.hpp> namespace po = boost::program_options; int main(int argc, char* argv[]) { po::options_description recipients("Recipient(s)"); recipients.add_options() ("csv", po::value<std::string>(), "" ) ("csv_name", po::value<unsigned>(), "" ) ; po::options_description cmdline_options; cmdline_options.add(recipients); po::variables_map vm; po::store(po::command_line_parser(argc, argv).options(cmdline_options).run(), vm); po::notify(vm); return 0; } And some tests: >Test --csv test in option 'csv_name': invalid option value >Test --csv_name test in option 'csv_name': invalid option value >Test --csv_name 0 >Test --csv text in option 'csv_name': invalid option value >Test --csv 0 >Test --csv_name 0 >Test --csv_name 0 --csv text multiple occurrences Looks like that boost::program_option threats parameter "csv" as "csv_name". Is it a feature or bug?

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  • Reading from serial port with Boost Asio?

    - by trikri
    Hi! I'm going to check for incoming messages (data packages) on the serial port, using Boost Asio. Each message will start with a header that is one byte long, and will specify which type of the message has been sent. Each different type of message has an own length. The function I'm about to write should check for new incoming messages continually, and when it finds one it should read it, and then some other function should parse it. I thought that the code might look something like this: void check_for_incoming_messages() { boost::asio::streambuf response; boost::system::error_code error; std::string s1, s2; if (boost::asio::read(port, response, boost::asio::transfer_at_least(0), error)) { s1 = streambuf_to_string(response); int msg_code = s1[0]; if (msg_code < 0 || msg_code >= NUM_MESSAGES) { // Handle error, invalid message header } if (boost::asio::read(port, response, boost::asio::transfer_at_least(message_lengths[msg_code]-s1.length()), error)) { s2 = streambuf_to_string(response); // Handle the content of s1 and s2 } else if (error != boost::asio::error::eof) { throw boost::system::system_error(error); } } else if (error != boost::asio::error::eof) { throw boost::system::system_error(error); } } Is boost::asio::streambuf is the right thing to use? And how do I extract the data from it so I can parse the message? I also want to know if I need to have a separate thread which only calls this function, so that it get called more often? Isn't there a risk for loosing data in between two calls to the function otherwise, because so much data comes in that it can't be stored in the serial ports memory? I'm using Qt as a widget toolkit and I don't really know how long time it needs to process all it's events.

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  • Boost::Thread linking error on OSX?

    - by gct
    So I'm going nuts trying to figure this one out. Here's my basic setup: I'm compiling a shared library with a bunch of core functionality that uses a lot of boost stuff. We'll call this library libpf_core.so. It's linked with the boost static libraries, specifically the python, system, filesystem, thread, and program_options libraries. This all goes swimmingly. Now, I have a little test program called test_socketio which is compiled into a shared library (it's loaded as a plugin at runtime). It uses some boost stuff like boost::bind and boost::thread, and it's linked again libpf_core.so (which has the boost libraries included remember). When I go to compile test_socketio though, out of all my plugins it gives me a linking error: [ Building test_socketio ] g++ -c -pg -g -O0 -I/usr/local/include -I../include test_socketio.cc -o test_socketio.o g++ -shared test_socketio.o -lpy_core -o test_socketio.so Undefined symbols: "boost::lock_error::lock_error()", referenced from: boost::unique_lock<boost::mutex>::lock() in test_socketio.o ld: symbol(s) not found collect2: ld returned 1 exit status And I'm going crazy trying to figure out why this is. I've tried explicitly linking boost::thread into the plugin to no avail, tried ensuring that I'm using the boost headers associated with the libraries linked into libpf_core.so in case there was a conflict there. Is there something OSX specific regarding boost that I'm missing? In my searching on google I've seen a number of other people get this error but no one seems to have come up with a satisfactory solution.

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  • Java: JPQL date function to add a time period to another date

    - by bguiz
    SELECT x FROM SomeClass WHERE x.dateAtt BETWEEN CURRENT_DATE AND (CURRENT_DATE + 1 MONTH) In the above JPQL statement, SomeClass has a memebr dateAttr, which is a java.util.Date and has a @Temporal(javax.persistence.TemporalType.DATE) annotation. I need a way to do the (CURRENT_DATE + 1 MONTH) bit - it is obviously wrong in its current state - but cannot find the doc with the date function for JPQL. Can anyone point me in the direction of a doc that documents JPQL date functions (and also how to do this particular query)?

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  • boost::serialization with mutable members

    - by redmoskito
    Using boost::serialization, what's the "best" way to serialize an object that contains cached, derived values in mutable members, such that cached members aren't serialized, but on deserialization, they are initialized the their appropriate default. A definition of "best" follows later, but first an example: class Example { public: Example(float n) : num(n), sqrt_num(-1.0) {} float get_num() const { return num; } // compute and cache sqrt on first read float get_sqrt() const { if(sqrt_num < 0) sqrt_num = sqrt(num); return sqrt_num; } template <class Archive> void serialize(Archive& ar, unsigned int version) { ... } private: float num; mutable float sqrt_num; }; On serialization, only the "num" member should be saved. On deserialization, the sqrt_num member must be initialized to its sentinel value indicating it needs to be computed. What is the most elegant way to implement this? In my mind, an elegant solution would avoid splitting serialize() into separate save() and load() methods (which introduces maintenance problems). One possible implementation of serialize: template <class Archive> void serialize(Archive& ar, unsigned int version) { ar & num; sqrt_num = -1.0; } This handles the deserialization case, but in the serialization case, the cached value is killed and must be recomputed. Also, I've never seen an example of boost::serialize that explicitly sets members inside of serialize(), so I wonder if this is generally not recommended. Some might suggest that the default constructor handles this, for example: int main() { Example e; { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> e; } cout << e.get_sqrt() << endl; return 0; } which works in this case, but I think fails if the object receiving the deserialized data has already been initialized, as in the example below: int main() { Example ex1(4); Example ex2(9); cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; // the following two blocks should implement ex2 = ex1; // save ex1 to archive { std::ofstream ofs("filename"); boost::archive::text_oarchive oa(ofs); oa << ex1; } // read it back into ex2 { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> ex2; } // these should be equal now, but aren't, // since Example::serialize() doesn't modify num_sqrt cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; return 0; } I'm sure this issue has come up with others, but I have struggled to find any documentation on this particular scenario. Thanks!

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  • Finding date between start date and end date

    - by Pankaj Khurana
    Hi, I want to check whether a date is between start date and end date. i have added a where class where datepaid between '2010-04-01' AND '2010-04-15' but the problem is that it excludes '2010-04-15'. It should include end date also how can i do this? Please help me on this Regards, pankaj

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