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  • GC output clarification

    - by elec
    I'm running a java application with the following settings: -XX:+CMSParallelRemarkEnabled -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+PrintGCApplicationStoppedTime -XX:+PrintGCApplicationConcurrentTime -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC -XX:+PrintTenuringDistribution I'm not sure how to interpret the related gc logs(below). In particular: Heap after GC invocations=31 (full 3): does this mean there were 31 minor GCs, and 3 full GCs ? What triggers the several consecutive lines of Total time for which the application threads were stopped and Application Time ? Is it possible to get the time stamps associated with each of these lines ? GC logs: Total time for which application threads were stopped: 0.0046910 seconds Application time: 0.7946670 seconds Total time for which application threads were stopped: 0.0002900 seconds Application time: 1.0153640 seconds Total time for which application threads were stopped: 0.0002780 seconds Application time: 1.0161890 seconds Total time for which application threads were stopped: 0.0002760 seconds Application time: 1.0145990 seconds Total time for which application threads were stopped: 0.0002950 seconds Application time: 0.9999800 seconds Total time for which application threads were stopped: 0.0002770 seconds Application time: 1.0151640 seconds Total time for which application threads were stopped: 0.0002730 seconds Application time: 0.9996590 seconds Total time for which application threads were stopped: 0.0002880 seconds Application time: 0.9624290 seconds {Heap before GC invocations=30 (full 3): par new generation total 131008K, used 130944K [0x00000000eac00000, 0x00000000f2c00000, 0x00000000f2c00000) eden space 130944K, 100% used [0x00000000eac00000, 0x00000000f2be0000, 0x00000000f2be0000) from space 64K, 0% used [0x00000000f2bf0000, 0x00000000f2bf0000, 0x00000000f2c00000) to space 64K, 0% used [0x00000000f2be0000, 0x00000000f2be0000, 0x00000000f2bf0000) concurrent mark-sweep generation total 131072K, used 48348K [0x00000000f2c00000, 0x00000000fac00000, 0x00000000fac00000) concurrent-mark-sweep perm gen total 30000K, used 19518K [0x00000000fac00000, 0x00000000fc94c000, 0x0000000100000000) 2010-05-11T09:30:13.888+0100: 384.955: [GC 384.955: [ParNew Desired survivor size 32768 bytes, new threshold 0 (max 0) : 130944K-0K(131008K), 0.0052470 secs] 179292K-48549K(262080K), 0.0053030 secs] [Times: user=0.00 sys=0.00, real=0.01 secs] Heap after GC invocations=31 (full 3): par new generation total 131008K, used 0K [0x00000000eac00000, 0x00000000f2c00000, 0x00000000f2c00000) eden space 130944K, 0% used [0x00000000eac00000, 0x00000000eac00000, 0x00000000f2be0000) from space 64K, 0% used [0x00000000f2be0000, 0x00000000f2be0000, 0x00000000f2bf0000) to space 64K, 0% used [0x00000000f2bf0000, 0x00000000f2bf0000, 0x00000000f2c00000) concurrent mark-sweep generation total 131072K, used 48549K [0x00000000f2c00000, 0x00000000fac00000, 0x00000000fac00000) concurrent-mark-sweep perm gen total 30000K, used 19518K [0x00000000fac00000, 0x00000000fc94c000, 0x0000000100000000) } Total time for which application threads were stopped: 0.0056410 seconds Application time: 0.0475220 seconds Total time for which application threads were stopped: 0.0001800 seconds Application time: 1.0174830 seconds Total time for which application threads were stopped: 0.0003820 seconds Application time: 1.0126350 seconds Total time for which application threads were stopped: 0.0002750 seconds Application time: 1.0155910 seconds Total time for which application threads were stopped: 0.0002680 seconds Application time: 1.0155580 seconds Total time for which application threads were stopped: 0.0002880 seconds Application time: 1.0155480 seconds Total time for which application threads were stopped: 0.0002970 seconds Application time: 0.9896810 seconds

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  • MySQL Join/Comparison on a DATETIME column (<5.6.4 and > 5.6.4)

    - by Simon
    Suppose i have two tables like so: Events ID (PK int autoInc), Time (datetime), Caption (varchar) Position ID (PK int autoinc), Time (datetime), Easting (float), Northing (float) Is it safe to, for example, list all the events and their position if I am using the Time field as my joining criteria? I.e.: SELECT E.*,P.* FROM Events E JOIN Position P ON E.Time = P.Time OR, even just simply comparing a datetime value (taking into consideration that the parameterized value may contain the fractional seconds part - which MySQL has always accepted) e.g. SELECT E.* FROM Events E WHERE E.Time = @Time I understand MySQL (before version 5.6.4) only stores datetime fields WITHOUT milliseconds. So I would assume this query would function OK. However as of version 5.6.4, I have read MySQL can now store milliseconds with the datetime field. Assuming datetime values are inserted using functions such as NOW(), the milliseconds are truncated (<5.6.4) which I would assume allow the above query to work. However, with version 5.6.4 and later, this could potentially NOT work. I am, and only ever will be interested in second accuracy. If anyone could answer the following questions would be greatly appreciated: In General, how does MySQL compare datetime fields against one another (consider the above query). Is the above query fine, and does it make use of indexes on the time fields? (MySQL < 5.6.4) Is there any way to exclude milliseconds? I.e. when inserting and in conditional joins/selects etc? (MySQL 5.6.4) Will the join query above work? (MySQL 5.6.4) EDIT I know i can cast the datetimes, thanks for those that answered, but i'm trying to tackle the root of the problem here (the fact that the storage type/definition has been changed) and i DO NOT want to use functions in my queries. This negates all my work of optimizing queries applying indexes etc, not to mention having to rewrite all my queries. EDIT2 Can anyone out there suggest a reason NOT to join on a DATETIME field using second accuracy?

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  • Format External HD on Airport Extreme Base Station?

    - by David.Chu.ca
    I just got an Airport Extreme Base Station. I am planning to use this one replace my current Linksys router. This works fine. My another purpose of getting this device is to use its USB port to connect to several external HDs as my backup Time Machine. I can see one 500GB HD through Airport Base Station. However, I cannot format it by using Disk Utility. What I did is to connect the HD to my iMac directly first and then clean and format the disk by Disk Utility application. Then I move the HD to the Airport Base Station. After that I can designate the HD as my Time Machine destination. Is there any way to format the HD connected to Airport Base Station? Any issues to use an external HD through Airport Base Station for Time Machine backups?

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  • Linux/Apache performance very slow even on local network

    - by klausch
    I have an Ubuntu server machine running Apache and MYSQL. System and version info is as follows: Linux kernel 3.0.0.-12 Apache/2.2.20 MySQL Ver 14.14.Distrib 5.1.58 I am running a few websites on this server, some HTML only, some PHP/MySQL. THe [problem is that response time is very slow, both on static as well as the dynamic sites. Sometimes it takes more than 10 seconds before a response is given, this makes the sites very slow and almost unusable. The problem occurs even when requesting from the local network. I have added the involved subdomains to my /etc/hosts file, and abolve all the problem is not solved by using IP numbers instead of URL's. So there is no DNS lookup issue. I have modified the log format by showing the response times and sometimes a files takes 12 seconds to be served, see the jquery~.js file in the example screenshot. I have no explanation for this extremely long response time, but is is not even the only issue here, some other files takes a long time to be served too, but do not show a long response time in the log file. So probably different tissues are involved here. I cannot find a solution until now, any suggestions??? THanx in advance, Klaas link to screenshot picture from access logfile Some extra configuration info: apache2.conf (comment is removed) LockFile ${APACHE_LOCK_DIR}/accept.lock PidFile ${APACHE_PID_FILE} Timeout 300 KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 5 <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_worker_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_event_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> User ${APACHE_RUN_USER} Group ${APACHE_RUN_GROUP} AccessFileName .htaccess <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> DefaultType text/plain HostnameLookups Off ErrorLog ${APACHE_LOG_DIR}/error.log LogLevel warn Include mods-enabled/*.load Include mods-enabled/*.conf Include httpd.conf Include ports.conf LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\" %T/%D" combined LogFormat "%h %l %u %t \"%r\" %>s %O" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent Include conf.d/ Include sites-enabled/ And the virtual hostfile for one of the slow sites, in fact it is pretty straightforward... <VirtualHost *:80> ServerAdmin [email protected] ServerSignature EMail ServerName toenjoy.drsklaus.nl DocumentRoot /var/www/toenjoy.drsklaus.nl <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /var/www/toenjoy.drsklaus.nl/> Options Indexes FollowSymLinks MultiViews AllowOverride AuthConfig AuthType Basic AuthName "To Enjoy" AuthUserFile /etc/.htpasswd Require user petraaa Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog /var/log/apache2/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> </VirtualHost> And the output of free -m: klaas@ubuntu-server:/etc/apache2$ free -m total used free shared buffers cached Mem: 1997 1401 595 0 144 1017 -/+ buffers/cache: 238 1758 Swap: 2035 0 2035 and I have no indication that swapping occurs on the moments the site is slow. I have runned top and it does not appear to be a CPU issue. I have the impression that the spawning of a apache thread could maybe be the bottleneck but it is just a suggestion. Maybe this gives some extra information! EDIT: The problem seemed to be gone for some time but occurs again! And not only with Apache, also connecting using SSH takes a tremendous time, sometimes it takes up to 15 seconds before the keyphrase is asked for. Also scp works very slowly. The behavious is really unpredoctable and makes the server very hard to use. Any ideas...?

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  • C#: My World Clock

    - by Bruce Eitman
    [Placeholder:  I will post the entire project soon] I have been working on cleaning my office of 8 years of stuff from several engineers working on many projects.  It turns out that we have a few extra single board computers with displays, so at the end of the day last Friday I though why not create a little application to display the time, you know, a clock.  How difficult could that be?  It turns out that it is quite simple – until I decided to gold plate the project by adding time displays for our offices around the world. I decided to use C#, which actually made creating the main clock quite easy.   The application was simply a text box and a timer.  I set the timer to fire a couple of times a second, and when it does use a DateTime object to get the current time and retrieve a string to display. And I could have been done, but of course that gold plating came up.   Seems simple enough, simply offset the time from the local time to the location that I want the time for and display it.    Sure enough, I had the time displayed for UK, Italy, Kansas City, Japan and China in no time at all. But it is October, and for those of us still stuck with Daylight Savings Time, we know that the clocks are about to change.   My first attempt was to simply check to see if the local time was DST or Standard time, then change the offset for China.  China doesn’t have Daylight Savings Time. If you know anything about the time changes around the world, you already know that my plan is flawed – in a big way.   It turns out that the transitions in and out of DST take place at different times around the world.   If you didn’t know that, do a quick search for “Daylight Savings” and you will find many WEB sites dedicated to tracking the time changes dates, and times. Now the real challenge of this application; how do I programmatically find out when the time changes occur and handle them correctly?  After a considerable amount of research it turns out that the solution is to read the data from the registry and parse it to figure out when the time changes occur. Reading Time Change Information from the Registry Reading the data from the registry is simple, using the data is a little more complicated.  First, reading from the registry can be done like:             byte[] binarydata = (byte[])Registry.GetValue("HKEY_LOCAL_MACHINE\\Time Zones\\Eastern Standard Time", "TZI", null);   Where I have hardcoded the registry key for example purposes, but in the end I will use some variables.   We now have a binary blob with the data, but it needs to be converted to use the real data.   To start we will need a couple of structs to hold the data and make it usable.   We will need a SYSTEMTIME and REG_TZI_FORMAT.   You may have expected that we would need a TIME_ZONE_INFORMATION struct, but we don’t.   The data is stored in the registry as a REG_TZI_FORMAT, which excludes some of the values found in TIME_ZONE_INFORMATION.     struct SYSTEMTIME     {         internal short wYear;         internal short wMonth;         internal short wDayOfWeek;         internal short wDay;         internal short wHour;         internal short wMinute;         internal short wSecond;         internal short wMilliseconds;     }       struct REG_TZI_FORMAT     {         internal long Bias;         internal long StdBias;         internal long DSTBias;         internal SYSTEMTIME StandardStart;         internal SYSTEMTIME DSTStart;     }   Now we need to convert the binary blob to a REG_TZI_FORMAT.   To do that I created the following helper functions:         private void BinaryToSystemTime(ref SYSTEMTIME ST, byte[] binary, int offset)         {             ST.wYear = (short)(binary[offset + 0] + (binary[offset + 1] << 8));             ST.wMonth = (short)(binary[offset + 2] + (binary[offset + 3] << 8));             ST.wDayOfWeek = (short)(binary[offset + 4] + (binary[offset + 5] << 8));             ST.wDay = (short)(binary[offset + 6] + (binary[offset + 7] << 8));             ST.wHour = (short)(binary[offset + 8] + (binary[offset + 9] << 8));             ST.wMinute = (short)(binary[offset + 10] + (binary[offset + 11] << 8));             ST.wSecond = (short)(binary[offset + 12] + (binary[offset + 13] << 8));             ST.wMilliseconds = (short)(binary[offset + 14] + (binary[offset + 15] << 8));         }             private REG_TZI_FORMAT ConvertFromBinary(byte[] binarydata)         {             REG_TZI_FORMAT RTZ = new REG_TZI_FORMAT();               RTZ.Bias = binarydata[0] + (binarydata[1] << 8) + (binarydata[2] << 16) + (binarydata[3] << 24);             RTZ.StdBias = binarydata[4] + (binarydata[5] << 8) + (binarydata[6] << 16) + (binarydata[7] << 24);             RTZ.DSTBias = binarydata[8] + (binarydata[9] << 8) + (binarydata[10] << 16) + (binarydata[11] << 24);             BinaryToSystemTime(ref RTZ.StandardStart, binarydata, 4 + 4 + 4);             BinaryToSystemTime(ref RTZ.DSTStart, binarydata, 4 + 16 + 4 + 4);               return RTZ;         }   I am the first to admit that there may be a better way to get the settings from the registry and into the REG_TXI_FORMAT, but I am not a great C# programmer which I have said before on this blog.   So sometimes I chose brute force over elegant. Now that we have the Bias information and the start date information, we can start to make sense of it.   The bias is an offset, in minutes, from local time (if already in local time for the time zone in question) to get to UTC – or as Microsoft defines it: UTC = local time + bias.  Standard bias is an offset to adjust for standard time, which I think is usually zero.   And DST bias is and offset to adjust for daylight savings time. Since we don’t have the local time for a time zone other than the one that the computer is set to, what we first need to do is convert local time to UTC, which is simple enough using:                 DateTime.Now.ToUniversalTime(); Then, since we have UTC we need to do a little math to alter the formula to: local time = UTC – bias.  In other words, we need to subtract the bias minutes. I am ahead of myself though, the standard and DST start dates really aren’t dates.   Instead they indicate the month, day of week and week number of the time change.   The dDay member of SYSTEM time will be set to the week number of the date change indicating that the change happens on the first, second… day of week of the month.  So we need to convert them to dates so that we can determine which bias to use, and when to change to a different bias.   To do that, I wrote the following function:         private DateTime SystemTimeToDateTimeStart(SYSTEMTIME Time, int Year)         {             DayOfWeek[] Days = { DayOfWeek.Sunday, DayOfWeek.Monday, DayOfWeek.Tuesday, DayOfWeek.Wednesday, DayOfWeek.Thursday, DayOfWeek.Friday, DayOfWeek.Saturday };             DateTime InfoTime = new DateTime(Year, Time.wMonth, Time.wDay == 1 ? 1 : ((Time.wDay - 1) * 7) + 1, Time.wHour, Time.wMinute, Time.wSecond, DateTimeKind.Utc);             DateTime BestGuess = InfoTime;             while (BestGuess.DayOfWeek != Days[Time.wDayOfWeek])             {                 BestGuess = BestGuess.AddDays(1);             }             return BestGuess;         }   SystemTimeToDateTimeStart gets two parameters; a SYSTEMTIME and a year.   The reason is that we will try this year and next year because we are interested in start dates that are in the future, not the past.  The function starts by getting a new Datetime with the first possible date and then looking for the correct date. Using the start dates, we can then determine the correct bias to use, and the next date that time will change:             NextTimeChange = StandardChange;             CurrentBias = TimezoneSettings.Bias + TimezoneSettings.DSTBias;             if (DSTChange.Year != 1 && StandardChange.Year != 1)             {                 if (DSTChange.CompareTo(StandardChange) < 0)                 {                     NextTimeChange = DSTChange;                     CurrentBias = TimezoneSettings.StdBias + TimezoneSettings.Bias;                 }             }             else             {                 // I don't like this, but it turns out that China Standard Time                 // has a DSTBias of -60 on every Windows system that I tested.                 // So, if no DST transitions, then just use the Bias without                 // any offset                 CurrentBias = TimezoneSettings.Bias;             }   Note that some time zones do not change time, in which case the years will remain set to 1.   Further, I found that the registry settings are actually wrong in that the DST Bias is set to -60 for China even though there is not DST in China, so I ignore the standard and DST bias for those time zones. There is one thing that I have not solved, and don’t plan to solve.  If the time zone for this computer changes, this application will not update the clock using the new time zone.  I tell  you this because you may need to deal with it – I do not because I won’t let the user get to the control panel applet to change the timezone. Copyright © 2012 – Bruce Eitman All Rights Reserved

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  • When decomposing a large function, how can I avoid the complexity from the extra subfunctions?

    - by missingno
    Say I have a large function like the following: function do_lots_of_stuff(){ { //subpart 1 ... } ... { //subpart N ... } } a common pattern is to decompose it into subfunctions function do_lots_of_stuff(){ subpart_1(...) subpart_2(...) ... subpart_N(...) } I usually find that decomposition has two main advantages: The decomposed function becomes much smaller. This can help people read it without getting lost in the details. Parameters have to be explicitly passed to the underlying subfunctions, instead of being implicitly available by just being in scope. This can help readability and modularity in some situations. However, I also find that decomposition has some disadvantages: There are no guarantees that the subfunctions "belong" to do_lots_of_stuff so there is nothing stopping someone from accidentally calling them from a wrong place. A module's complexity grows quadratically with the number of functions we add to it. (There are more possible ways for things to call each other) Therefore: Are there useful convention or coding styles that help me balance the pros and cons of function decomposition or should I just use an editor with code folding and call it a day? EDIT: This problem also applies to functional code (although in a less pressing manner). For example, in a functional setting we would have the subparts be returning values that are combined in the end and the decomposition problem of having lots of subfunctions being able to use each other is still present. We can't always assume that the problem domain will be able to be modeled on just some small simple types with just a few highly orthogonal functions. There will always be complicated algorithms or long lists of business rules that we still want to correctly be able to deal with. function do_lots_of_stuff(){ p1 = subpart_1() p2 = subpart_2() pN = subpart_N() return assembleStuff(p1, p2, ..., pN) }

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  • Program crash on deque from queue

    - by SwedishGit
    My first question asked here, so please excuse if I fail to include something... I'm working on a homework project, which basically consists of creating a "Jukebox" (importing/exporting albums from txt files, creating and "playing" a playlist, etc.). I've become stuck on one point: When "playing" the playlist, which consists of a self-made Queue, a copy of it is made from which songs are dequeued and printed out with a time delay. This appears to run fine on the first run through the program, but if the "play" option is chosen again (with the same playlist, created from a different menu option), it crashes before managing to print the first song. It also crashes if creating a new playlist, but then it manages to print some songs (seem to depend on the number of songs in the first/new playlists...) before crashing. With printouts I've been able to track the crashing down to being on the "item = n-data" call in the deque function... but can't get my head around why this would crash. Below is the code I think should be relevant... let me know if there are other parts that would help if I include. Edit: The Debug Error shown on crash is: R6010 abort() has been called The method to play from the playlist: void Jukebox::playList() { if(songList.getNodes() > 0) { Queue tmpList(songList); Song tmpSong; while(tmpList.deque(tmpSong)) { clock_t temp; temp = clock () + 2 * CLOCKS_PER_SEC ; while (clock() < temp) {} } } else cout << "There are no songs in the playlist!" << endl; } Queue: // Queue.h - Projekt-uppgift // Håkan Sjölin 2014-05-31 //----------------------------------------------------------------------------- #ifndef queue_h #define queue_h #include "Song.h" using namespace std; typedef Song Item; class Node; class Queue { private: Node *first; Node *last; int nodes; public: Queue():first(nullptr),last(nullptr),nodes(0){}; ~Queue(); void enque(Item item); bool deque(Item &item); int getNodes() const { return nodes; } void empty(); }; #endif // Queue.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-31 //----------------------------------------------------------------------------- #include "queue.h" using namespace std; class Node { public: Node *next; Item data; Node (Node *n, Item newData) : next(n), data(newData) {} }; //------------------------------------------------------------------------------ // Funktionsdefinitioner för klassen Queue //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // Destruktor //------------------------------------------------------------------------------ Queue::~Queue() { while(first!=0) { Node *tmp = first; first = first->next; delete tmp; } } //------------------------------------------------------------------------------ // Lägg till data sist i kön //------------------------------------------------------------------------------ void Queue::enque(Item item) { Node *pNew = new Node(0,item); if(getNodes() < 1) first = pNew; else last->next = pNew; last = pNew; nodes++; } //------------------------------------------------------------------------------ // Ta bort data först i kön //------------------------------------------------------------------------------ bool Queue::deque(Item &item) { if(getNodes() < 1) return false; //cout << "deque: test2" << endl; Node *n = first; //cout << "deque: test3" << endl; //cout << "item = " << item << endl; //cout << "first = " << first << endl; //cout << "n->data = " << n->data << endl; item = n->data; //cout << "deque: test4" << endl; first = first->next; //delete n; nodes--; if(getNodes() < 1) // Kön BLEV tom last = nullptr; return true; } //------------------------------------------------------------------------------ // Töm kön //------------------------------------------------------------------------------ void Queue::empty() { while (getNodes() > 0) { Item item; deque(item); } } //------------------------------------------------------------------------------ Song: // Song.h - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #ifndef song_h #define song_h #include "Time.h" #include <string> #include <iostream> using namespace std; class Song { private: string title; string artist; Time length; public: Song(); Song(string pTitle, string pArtist, Time pLength); // Setfunktioner void setTitle(string pTitle); void setArtist(string pArtist); void setLength(Time pLength); // Getfunktioner string getTitle() const { return title;} string getArtist() const { return artist;} Time getLength() const { return length;} }; ostream &operator<<(ostream &os, const Song &song); istream &operator>>(istream &is, Song &song); #endif // Song.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #include "Song.h" #include "Constants.h" #include <iostream> //------------------------------------------------------------------------------ // Definiering av Songs medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Song::Song() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Song::Song(string pTitle, string pArtist, Time pLength) { title = pTitle; artist = pArtist; length = pLength; } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setTitle // Ange titel //------------------------------------------------------------------------------ void Song::setTitle(string pTitle) { title = pTitle; } //------------------------------------------------------------------------------ // setArtist // Ange artist //------------------------------------------------------------------------------ void Song::setArtist(string pArtist) { artist = pArtist; } //------------------------------------------------------------------------------ // setTitle // Ange titel //------------------------------------------------------------------------------ void Song::setLength(Time pLength) { length = pLength; } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Song &song) { os << song.getTitle() << DELIM << song.getArtist() << DELIM << song.getLength(); return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Song &song) { string tmpString; Time tmpLength; getline(is, tmpString, DELIM); song.setTitle(tmpString); getline(is, tmpString, DELIM); song.setArtist(tmpString); is >> tmpLength; is.get(); song.setLength(tmpLength); return is; } //--------------------------------------------------------------------------- Album: // Album.h - Projekt-uppgift // Håkan Sjölin 2014-05-17 //----------------------------------------------------------------------------- #ifndef album_h #define album_h #include "Song.h" #include <string> #include <vector> #include <iostream> using namespace std; class Album { private: string name; vector<Song> songs; public: Album(); Album(string pNameTitle, vector<Song> pSongs); // Setfunktioner void setName(string pName); // Getfunktioner string getName() const { return name;} vector<Song> getSongs() const { return songs;} int getNumberOfSongs() const { return songs.size();} Time getTotalTime() const; void addSong(Song pSong); bool operator<(const Album &album) const; }; ostream &operator<<(ostream &os, const Album &album); istream &operator>>(istream &is, Album &album); #endif // Album.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-17 //----------------------------------------------------------------------------- #include "Album.h" #include "Constants.h" #include <iostream> #include <string> //------------------------------------------------------------------------------ // Definiering av Albums medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Album::Album() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Album::Album(string pName, vector<Song> pSongs) { name = pName; songs = pSongs; } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setName // Ange namn //------------------------------------------------------------------------------ void Album::setName(string pName) { name = pName; } //------------------------------------------------------------------------------ // addSong // Lägg till song //------------------------------------------------------------------------------ void Album::addSong(Song pSong) { songs.push_back(pSong); } //------------------------------------------------------------------------------ // getTotalTime // Returnera total speltid //------------------------------------------------------------------------------ Time Album::getTotalTime() const { Time tTime(0,0,0); for(Song s : songs) { tTime = tTime + s.getLength(); } return tTime; } //--------------------------------------------------------------------------- // Mindre än //--------------------------------------------------------------------------- bool Album::operator<(const Album &album) const { return getTotalTime() < album.getTotalTime(); } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Album &album) { os << album.getName() << endl; os << album.getNumberOfSongs() << endl; for (size_t i = 0; i < album.getSongs().size(); i++) os << album.getSongs().at(i) << endl; return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Album &album) { string tmpString; int tmpNumberOfSongs; Song tmpSong; getline(is, tmpString); album.setName(tmpString); is >> tmpNumberOfSongs; is.get(); for (int i = 0; i < tmpNumberOfSongs; i++) { is >> tmpSong; album.addSong(tmpSong); } return is; } //--------------------------------------------------------------------------- Time: // Time.h - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #ifndef time_h #define time_h #include <iostream> using namespace std; class Time { private: int hours; int minutes; int seconds; public: Time(); Time(int pHour, int pMinute, int pSecond); // Setfunktioner void setHour(int pHour); void setMinute(int pMinute); void setSecond(int pSecond); // Getfunktioner int getHour() const { return hours;} int getMinute() const { return minutes;} int getSecond() const { return seconds;} Time operator+(const Time &time) const; bool operator==(const Time &time) const; bool operator<(const Time &time) const; }; ostream &operator<<(ostream &os, const Time &time); istream &operator>>(istream &is, Time &Time); #endif // Time.cpp - Projekt-uppgift // Håkan Sjölin 2014-05-15 //----------------------------------------------------------------------------- #include "Time.h" #include <iostream> //------------------------------------------------------------------------------ // Definiering av Times medlemsfunktioner //------------------------------------------------------------------------------ // Fövald konstruktor //------------------------------------------------------------------------------ Time::Time() { } //------------------------------------------------------------------------------ // Initieringskonstruktor //------------------------------------------------------------------------------ Time::Time(int pHour, int pMinute, int pSecond) { setHour(pHour); setMinute(pMinute); setSecond(pSecond); } //------------------------------------------------------------------------------ // Setfunktioner //------------------------------------------------------------------------------ //------------------------------------------------------------------------------ // setHour // Ange timme //------------------------------------------------------------------------------ void Time::setHour(int pHour) { if(pHour>-1) hours = pHour; else hours = 0; } //------------------------------------------------------------------------------ // setMinute // Ange minut //------------------------------------------------------------------------------ void Time::setMinute(int pMinute) { if(pMinute < 60 && pMinute > -1) { minutes = pMinute; } else minutes = 0; } //------------------------------------------------------------------------------ // setSecond // Ange sekund //------------------------------------------------------------------------------ void Time::setSecond(int pSecond) { if(pSecond < 60 && pSecond > -1) { seconds = pSecond; } else seconds = 0; } //--------------------------------------------------------------------------- // Överlagring av utskriftsoperatorn //--------------------------------------------------------------------------- ostream &operator<<(ostream &os, const Time &time) { os << time.getHour()*3600+time.getMinute()*60+time.getSecond(); return os; } //--------------------------------------------------------------------------- // Överlagring av inmatningsoperatorn //--------------------------------------------------------------------------- istream &operator>>(istream &is, Time &time) { int tmp; is >> tmp; time.setSecond(tmp%60); time.setMinute((tmp/60)%60); time.setHour(tmp/3600); return is; } //--------------------------------------------------------------------------- // Likhet //-------------------------------------------------------------------------- bool Time::operator==(const Time &time) const { return hours == time.getHour() && minutes == time.getMinute() && seconds == time.getSecond(); } //--------------------------------------------------------------------------- // Mindre än //--------------------------------------------------------------------------- bool Time::operator<(const Time &time) const { if(hours == time.getHour()) { if(minutes == time.getMinute()) { return seconds < time.getSecond(); } else { return minutes < time.getMinute(); } } else { return hours < time.getHour(); } } //--------------------------------------------------------------------------- // Addition //--------------------------------------------------------------------------- Time Time::operator+(const Time &time) const { return Time(hours+time.getHour() + (minutes+time.getMinute() + (seconds+time.getSecond())/60)/60, (minutes+time.getMinute() + (seconds+time.getSecond())/60)%60, (seconds+time.getSecond())%60); } //--------------------------------------------------------------------------- Thanks in advance for any help! Edit2: Didn't think of including the more detailed crash info (as it didn't show in the crash pop-up, so to say). Anyway, here it is: Output: 'Jukebox.exe' (Win32): Loaded 'C:\Users\Håkan\Documents\Studier - IT\Objektbaserad programmering i C++\Inlämningsuppgifter\Projekt\Jukebox\Debug\Jukebox.exe'. Symbols loaded. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\ntdll.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\kernel32.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\KernelBase.dll'. Cannot find or open the PDB file. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcp110d.dll'. Symbols loaded. 'Jukebox.exe' (Win32): Loaded 'C:\Windows\SysWOW64\msvcr110d.dll'. Symbols loaded. The thread 0xe50 has exited with code 0 (0x0). Unhandled exception at 0x0083630C in Jukebox.exe: 0xC0000005: Access violation reading location 0x0000003C. Call stack: > Jukebox.exe!Song::getLength() Line 27 C++ Jukebox.exe!operator<<(std::basic_ostream<char,std::char_traits<char> > & os, const Song & song) Line 59 C++ Jukebox.exe!Queue::deque(Song & item) Line 55 C++ Jukebox.exe!Jukebox::playList() Line 493 C++ Jukebox.exe!Jukebox::play() Line 385 C++ Jukebox.exe!Jukebox::run() Line 536 C++ Jukebox.exe!main() Line 547 C++ Jukebox.exe!__tmainCRTStartup() Line 536 C Jukebox.exe!mainCRTStartup() Line 377 C kernel32.dll!754d86e3() Unknown [Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll] ntdll.dll!7748bf39() Unknown ntdll.dll!7748bf0c() Unknown

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  • Big 0 theta notation

    - by niggersak
    Can some pls help with the solution Use big-O notation to classify the traditional grade school algorithms for addition and multiplication. That is, if asked to add two numbers each having N digits, how many individual additions must be performed? If asked to multiply two N-digit numbers, how many individual multiplications are required? Suppose f is a function that returns the result of reversing the string of symbols given as its input, and g is a function that returns the concatenation of the two strings given as its input. If x is the string hrwa, what is returned by g(f(x),x)? Explain your answer - don't just provide the result!

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  • Proving that a function f(n) belongs to a Big-Theta(g(n))

    - by PLS
    Its a exercise that ask to indicate the class Big-Theta(g(n)) the functions belongs to and to prove the assertion. In this case f(n) = (n^2+1)^10 By definition f(n) E Big-Theta(g(n)) <= c1*g(n) < f(n) < c2*g(n), where c1 and c2 are two constants. I know that for this specific f(n) the Big-Theta is g(n^20) but I don't know who to prove it properly. I guess I need to manipulate this inequality but I don't know how

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  • Amazing families of algorithms over implicit graphs

    - by Diego de Estrada
    Dynamic programming is, almost by definition, to find a shortest/longest path on an implicit dag. Every DP algorithm just does this. An Holographic algorithm can be loosely described as something that counts perfect matchings in implicit planar graphs. So, my question is: are there any other families of algorithms that use well-known algorithms over implicit graphs to achieve a considerable speedup?

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  • Best jQuery/Prototype book for complex ajax?

    - by Burton Kent
    I've been working on a complex app with one main dashboard. I don't particularly like the design because it tries to do too much on one page. So the lead developer thought it would be a good idea to use ajax - because the page is so big. Refreshing part of it is far faster than loading it again. Problem is there's several ways data can be used. Adding items Editing rows Performing actions on selected rows (selected using a checkbox) Changing single items (like location, phone) My problem is making GENERALIZABLE ajax code that can operate on the data in a div, using class names to assemble the proper information for the ajax call. I did pretty well, but can't help but want to see if there's a better way to do it.

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  • RSA encryption results in server execution timeout

    - by Nilambari
    Hi, I am using PHP Crypt_RSA (http://pear.php.net/package/Crypt_RSA) for encrypting and decrypting the contents. Contents are of 1kb size. Following are the results: keylength = 1024 Encryption function takes time: 225 secs keylength = 2048 Encryption function takes time: 115 secs I need to reduce this execution time as most of the live apache servers have 120 sec limit for execution time. How to reduce this execution time? RSA alorithm docs says the only 1024 - 2048 keys are generated. I ACTUALLY tried to generate larger key, but it always results in execution timeout. How do i work on reducing encryption - decryption execution time? Thanks, Nila

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  • What is an XYZ-complete problem?

    - by TheMachineCharmer
    EDIT: Diagram: http://www.cs.umass.edu/~immerman/complexity_theory.html There must be some meaning to the word "complete" its used every now and then. Look at the diagram. I tried reading previous posts about NP- My question is what does the word "COMPLETE" mean? Why is it there? What is its significance? N- Non-deterministic - makes sense' P- Polynomial - makes sense but the "COMPLETE" is still a mystery for me.

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  • How to calculate order (big O) for more complex algorithms (ie quicksort)

    - by bangoker
    I know there are quite a bunch of questions about big O notation, I have already checked Plain english explanation of Big O , Big O, how do you calculate/approximate it?, and Big O Notation Homework--Code Fragment Algorithm Analysis?, to name a few. I know by "intuition" how to calculate it for n, n^2, n! and so, however I am completely lost on how to calculate it for algorithms that are log n , n log n, n log log n and so. What I mean is, I know that Quick Sort is n log n (on average).. but, why? Same thing for merge/comb, etc. Could anybody explain me in a not to math-y way how do you calculate this? The main reason is that Im about to have a big interview and I'm pretty sure they'll ask for this kind of stuff. I have researched for a few days now, and everybody seem to have either an explanation of why bubble sort is n^2 or the (for me) unreadable explanation a la wikipedia Thanks!

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  • The Immerman-Szelepcsenyi Theorem

    - by Daniel Lorch
    In the Immerman-Szelepcsenyi Theorem, two algorithms are specified that use non-determinisim. There is a rather lengthy algorithm using "inductive counting", which determines the number of reachable configurations for a given non-deterministic turing machine. The algorithm looks like this: Let m_{i+1}=0 For all configurations C Let b=0, r=0 For all configurations D Guess a path from I to D in at most i steps If found Let r=r+1 If D=C or D goes to C in 1 step Let b=1 If r<m_i halt and reject Let m_{i+1}=m_{i+1}+b I is the starting configuration. m_i is the number of configurations reachable from the starting configuration in i steps. This algorithm only calculates the "next step", i.e. m_i+1 from m_i. This seems pretty reasonable, but since we have nondeterminisim, why don't we just write: Let m_i = 0 For all configurations C Guess a path from I to C in at most i steps If found m_i = m_i + 1 What is wrong with this algorithm? I am using nondeterminism to guess a path from I to C, and I verify reachability I am iterating through the list of ALL configurations, so I am sure to not miss any configuration I respect space bounds I can generate a certificate (the list of reachable configs) I believe I have a misunderstanding of the "power" of non-determinisim, but I can't figure out where to look next. I am stuck on this for quite a while and I would really appreciate any help.

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  • Can NP-Intermediate exist if P = NP?

    - by Jason Baker
    My understanding is that Ladner's theorem is basically this: P != NP implies that there exists a set NPI where NPI is not in P and NPI is not NP-complete What happens to this theorem if we assume that P = NP rather than P != NP? We know that if NP Intermediate doesn't exist, then P = NP. But can NP Intermediate exist if P = NP?

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  • C++ Asymptotic Profiling

    - by Travis
    I have a performance issue where I suspect one standard C library function is taking too long and causing my entire system (suite of processes) to basically "hiccup". Sure enough if I comment out the library function call, the hiccup goes away. This prompted me to investigate what standard methods there are to prove this type of thing? What would be the best practice for testing a function to see if it causes an entire system to hang for a sec (causing other processes to be momentarily starved)? I would at least like to definitively correlate the function being called and the visible freeze. Thanks

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  • Append to a file in Java. Is it a joke?

    - by Roman
    I need to append some data to existing file. I started to browse Internet to find out how to do it. And I found this mini (as they say) application to do that: http://www.devdaily.com/java/edu/qanda/pjqa00009.shtml Well I was already annoyed by the fact how complicated are things in Java (in comparison with Python, for example). But this is too much! I just want to add to a file! It should be one line! Not 50! Or do I get something wrong?

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  • Whats the best data-structure for storing 2-tuple (a, b) which support adding, deleting tuples and c

    - by bhups
    Hi So here is my problem. I want to store 2-tuple (key, val) and want to perform following operations: - keys are strings and values are Integers - multiple keys can have same value - adding new tuples - updating any key with new value (any new value or updated value is greater than the previous one, like timestamps) - fetching all the keys with values less than or greater than given value - deleting tuples. Hash seems to be the obvious choice for updating the key's value but then lookups via values will be going to take longer (O(n)). The other option is balanced binary search tree with key and value switched. So now lookups via values will be fast (O(lg(n))) but updating a key will take (O(n)). So is there any data-structure which can be used to address these issues? Thanks.

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  • What data is actually stored in a B-tree database in CouchDB?

    - by Andrey Vlasovskikh
    I'm wondering what is actually stored in a CouchDB database B-tree? The CouchDB: The Definitive Guide tells that a database B-tree is used for append-only operations and that a database is stored in a single B-tree (besides per-view B-trees). So I guess the data items that are appended to the database file are revisions of documents, not the whole documents: +---------|### ... | | +------|###|------+ ... ---+ | | | | +------+ +------+ +------+ +------+ | doc1 | | doc2 | | doc1 | ... | doc1 | | rev1 | | rev1 | | rev2 | | rev7 | +------+ +------+ +------+ +------+ Is it true? If it is true, then how the current revision of a document is determined based on such a B-tree? Doesn't it mean, that CouchDB needs a separate "view" database for indexing current revisions of documents to preserve O(log n) access? Wouldn't it lead to race conditions while building such an index? (as far as I know, CouchDB uses no write locks).

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  • Why are difference lists more efficient than regular concatenation?

    - by Craig Innes
    I am currently working my way through the Learn you a haskell book online, and have come to a chapter where the author is explaining that some list concatenations can be ineffiecient: For example ((((a ++ b) ++ c) ++ d) ++ e) ++ f Is supposedly inefficient. The solution the author comes up with is to use 'difference lists' defined as newtype DiffList a = DiffList {getDiffList :: [a] -> [a] } instance Monoid (DiffList a) where mempty = DiffList (\xs -> [] ++ xs) (DiffList f) `mappend` (DiffList g) = DiffList (\xs -> f (g xs)) I am struggling to understand why DiffList is more computationally efficient than a simple concatenation in some cases. Could someone explain to me in simple terms why the above example is so inefficient, and in what way the DiffList solves this problem?

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  • is it possible to write a program which prints its own source code utilizing a "sequence-generating-

    - by guest
    is it possible to write a program which prints its own source code utilizing a "sequence-generating-function"? what i call a sequence-generating-function is simply a function which returns a value out of a specific interval (i.e. printable ascii-charecters (32-126)). the point now is, that this generated sequence should be the programs own source-code. as you see, implementing a function which returns an arbitrary sequence is really trivial, but since the returned sequence must contain the implementation of the function itself it is a highly non-trivial task. this is how such a program (and its corresponding output) could look like #include <stdio.h> int fun(int x) { ins1; ins2; ins3; . . . return y; } int main(void) { int i; for ( i=0; i<size of the program; i++ ) { printf("%c", fun(i)); } return 0; } i personally think it is not possible, but since i don't know very much about the underlying matter i posted my thoughts here. i'm really looking forward to hear some opinions!

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  • Java: Calculate distance between a large number of locations and performance

    - by Ally
    I'm creating an application that will tell a user how far away a large number of points are from their current position. Each point has a longitude and latitude. I've read over this article http://www.movable-type.co.uk/scripts/latlong.html and seen this post http://stackoverflow.com/questions/837872/calculate-distance-in-meters-when-you-know-longitude-and-latitude-in-java There are a number of calculations (50-200) that need carried about. If speed is more important than the accuracy of these calculations, which one is best?

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