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• Context switches much slower in new linux kernels

  - by Michael Goldshteyn

  We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to believe. Let me be more specific about the test. We have a program that has two threads. The first thread gets the current time (in ticks using RDTSC) and then signals a condition variable once a second. The second thread waits on the condition variable and wakes up when it is signaled. It then gets the current time (in ticks using RDTSC). The difference between the time in the second thread and the time in the first thread is computed and displayed on the console. After this the second thread waits on the condition variable once more. So, we get a thread to thread signaling latency measurement once a second as a result. In linux 2.6.32, this latency is somewhere on the order of 2.8-3.5 us, which is reasonable. In linux 3.2.0, this latency is somewhere on the order of 40-100 us. I have excluded any differences in hardware between the two host hosts. They run on identical hardware (dual socket X5687 {Westmere-EP} processors running at 3.6 GHz with hyperthreading, speedstep and all C states turned off). We are changing the affinity to run both threads on physical cores of the same socket (i.e., the first thread is run on Core 0 and the second thread is run on Core 1), so there is no bouncing of threads on cores or bouncing/communication between sockets. The only difference between the two hosts is that one is running Ubuntu 10.04 LTS with kernel 2.6.32-28 (the fast context switch box) and the other is running the latest Ubuntu 12.04 LTS with kernel 3.2.0-23 (the slow context switch box). Have there been any changes in the kernel that could account for this ridiculous slow down in how long it takes for a thread to be scheduled to run?

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• What precaution should I take to hire online freelancer designers? [on hold]

  - by tomDev

  For quite some time my company is super busy with our apps, and a few days ago someone contacted me by email offering his services to help me as a graphic designer. He has a fair price, a flickr portfolio (with great stuff but not popular at all), same on Twitter. I was really considering in hiring him for some specific service, but the question is... what precaution should I take when hiring someone I have no idea who is? I can't even be sure I have his real name and his real country. How do I make a contract? How do I pay? How do I know he will not sue us after the graphics reach the App Store asking for more money? And of course, how do I know he will actually do the service and not steal from some stock service? Am I a bit paranoiac or is this a common deal with graphics designers? PS: if someone asks I can provide his flickr, but I think this is a general question and not specific for this designer.

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• How "commercially savvy" should software developers be? [closed]

  - by mattnz

  I have been watching answers to many questions on this site, and have come to the conclusion that commercial pragmatism does not factor into many software development discussions. As a result, I seriously wonder at the commercial skills within the industry, specifically the ability to deliver projects on time and to a budget. I see no indication from the site that commercially successful project delivery is a serious concern, yet the industry has a reputation for poor performance in this. Rarely, if ever, does the cost of time factor into discussions. I have never seen concepts such as opportunity cost, time to market, competitive advantage or cash flow mentioned, let alone discussed in technical answers to questions. How can you answer virtually any question without understanding the commercial background on which it is asked? Even Open source projects have a need to operate efficiently and deploy their limited resources to providing the most value for effort. Typically small start-ups have cash flow issues that outweigh longevity concerns, yet they are typically still advised to build for a future they probably won’t have if they do. Is it fair to say that these problems are solely the Managers and Project managers to solve, or are we, as developers, also responsible for ensuring successful on time, within budget delivery of projects, even if those budgets do not allow use to achieve engineering excellence?

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• VMware Player 5.0 or VMware Workstation 9.0 after upgrade to Ubuntu 12.10

  The upgrade process Upgrading Ubuntu 12.04 to latest version 12.10 - aka Quantal Quetzal - is straight forward and you only need to follow the offical upgrade instructions. Short version on the console looks like this: sudo do-release-upgrade This will update the repository entries, and start the upgrade process. After some minutes or hours of download and installation, you have to reboot your system once to get the new kernel loaded. As time of writing, I'm on '3.5.0-17-generic'. And as with any modification of the kernel version, you have to compile the necessary kernel modules to get VMware Player or Workstation up and running. Usually, this happens the first time you try start your VMware software and that's it. Well, again not so this time. Getting the kernel patch Luckily, the community over VMware is very active and you can get a new kernel patch in the online forums here. Get the download and put in a folder have write permissions. Then you extract the archive on the console like so: tar -xjvf vmware9_kernel35_patch.tar.bz2 Then you change into the newly created folder: cd vmware9_kernel3.5_patch/ And you execute the available shell script as root (superuser) like so: sudo ./patch-modules_3.5.0.sh This will stop any running instances of VMware software, patches the source files and runs the compile process for your active environment. This might take some time depending on your machine, and once completed you can start VMware Player or Workstation as previously. In case that you are going to apply the patch again, the script will simply quit with the following output: /usr/lib/vmware/modules/source/.patched found. You have already patched your sources. Exiting You might remove the .patched file in case that you upgraded/changed your kernel and you need to apply the patch again. Disclaimer: The patch is "as-is" and the patcher is originally created by Artem S. Tashkinov, and later modified by An_tony. Please refer to the VMware forum in case of questions or problems. There are also patches available for older versions of VMware Player or Workstation.

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• What OO Design to use ( is there a Design Pattern )?

  - by Blundell

  I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, website url, logo So I've got two objects representing the same thing but with different fields. I like to use immutable objects, so all the fields are set from the constructor. One option is to have two constructors and null the other fields i.e: class Bar { private final String name; private final Distance distance; private final Url url; public Bar(String name, Distance distance){ this.name = name; this.distance = distance; this.url = null; } public Bar(String name, Url url){ this.name = name; this.distance = null; this.url = url; } // getters } I don't like this as you would have to null check when you use the getters In my real example the first scenario has 3 fields and the second scenario has about 10, so it would be a real pain having two constructors, the amount of fields I would have to declare null and then when the object are in use you wouldn't know which Bar you where using and so what fields would be null and what wouldn't. What other options do I have? Two classes called BarPreview and Bar? Some type of inheritance / interface? Something else that is awesome?

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• Best approach for tracking dependent state

  - by Pace

  Let's pretend I work on a project tracking application. The application is a database backed, server hosted, web application. In this application there are Projects which have many Activities which have many Tasks. A Task has two date fields an originalDueDate and a projectedDueDate. In addition, there are dynamic fields on the Activities and the Projects which indicate whether the Activity or Project is behind schedule based on the projected due dates of the child tasks and various other variables such as remaining buffer time, etc. There are a number of things that can cause the projectedDueDate to change. For example, an employee working on the project may (via a server request) enter in a shipping delay. Alternatively, a site may (via a server request) enter in an unexpected closure. When any of these things occur I need to not only update the projectedDueDate of the Task but also trigger the corresponding Project and Activity to update as well. What is the best way to do this? I've thought of the observer pattern but I don't keep a single copy of all these objects in memory. When a request comes in, I query the Task in from the database, at that point there is no associated Activity in memory that would be a listener. I could remove the ability to query for Tasks and force the application to query first by Project, then by Activity (in context of Project), then by task (in context of Activity) adding the observer relationships at each step but I'm not sure if that is the best way. I could setup a database event listening system so when a Task modified event is dispatched I have a handler which queries for the Activity at that point. I could simply setup a two-way relationship between Task and Activity so that the Task knows about the parent Activity and when the Task updates his state the Task grabs his parent and updates state. Right now I'm stuck considering all the options and am wondering if any single approach (doesn't have to be a listed approach) is jumping out at others as the best approach.

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• Steering evaluate fitness

  - by Vodemki

  I've made a simple game with a steering model that manage a crowd of agents. I use an genetic algorithm to find the best parameters to use in my system but I need to determine a fitness for each simulation. I know it's something like that: number of collisions * time to reach goal * effort But I don't know how to calculate the effort, is there a special way to do that ? Here is what I've done so far: // Evaluate the distance from agents to goal Real totalDistance(0.0); for (unsigned i=0; i<_agents.size(); i++) { totalDistance += _agents[i]->position().distance(_agents[i]->_goal->position()); } Real totalWallsCollision(0.0); for (unsigned i=0; i<_agents.size(); i++) { for (unsigned j=0; j<walls.size(); j++) { if ( walls[j]->inside(_agents[i]->position()) ) { totalCollision += 1.0; } } } return totalDistance + totalWallsCollision; Thanks for your help.

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• There's Not an App for That (Yet)

  - by Mark Hesse

  With an earlier-than-normal departure this morning to avoid the stalemate known as traffic congestion, I suddenly realized what I had failed to grab on my way out the door...  my company ID badge.  Unfortunately, at the time of my epiphany, I was far enough into commuter no-man's land where turning back would completely negate my early departure and increase my overall drive time exponentially.  Not being one to retrace my steps, I decided to press on. Upon arrival at the office and with an hour to go before a security guard would be on duty, I started thinking about the number of times I had forgotten my ID vs. the number of times I had forgotten my phone.  While rare on both accounts, my ID was most likely the missing artifact. I then wondered why there isn't an app for my smartphone that allows me to verify my credentials with my employer and then, provided with a secure token for the day, have the ability to access my building's card entry system.  On many levels, this seems much more secure than an ID card which can be lost, stolen or even forged and then used simply by tailgating into and around buildings at facilities where card scanning can generally be avoided.   As it turns out, another building on the campus has 24 x 7 guard coverage, so I was able to gain access in a relatively short time and secure a temporary ID badge.  Once inside and online, a quick internet search on the subject of smartphone badge access shows that efforts are underway to do exactly what I was thinking needed to be done. Having not spent any time studying about the technology, I discovered that it relies on Near Field Communications (NFC) enabled smartphones (of which, mine does not provide).  The only other option would require modifications to the security infrastructure to support alternative authentication technologies, such as barcode readers, which would be extremely costly to implement. For now, my best option is to put my corporate ID under my car keys... 

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• How come there is still so much programming work?

  - by jd_505

  First I'd like to say that I am not pretty sure that this question will meet the guidelines. I think it can goes under the "Freelancing and business concerns" bullet, but I am not sure. Anyway, I will give it a shot. I wonder how the programming jobs hasn't yet "dried" because of the software evolution, for example, I am a developer myself, which means that I do care about software (I mean I am not of the type of guys that needs a computer mainly to just browse the Internet), and still I wouldn't mind if I never receive any more updates on my Ubuntu machine. I find that it provides everything I need, and while the updates provide various bug fixes/improvements, I wouldn't mind using it with it's current state for the rest of my life, for 2 years of Ubuntu usage I have never bumped at a serious bug/problem. Another example is Windows, almost half of it's users still use XP, which is practically ancient, yet they find it satisfying all their needs (and I agreee with them). I could go with many more examples, but by now you are understanding my point and my question. While new "trends" appears all of the time (like a new mobile OS) which runs on new platforms and requires some fresh development work, still the majority of the software effort goes in to what I consider as "completed projects", or at least a state of a project which is enough to be considered as completed. Do you have an explanation ? I can't think of the right tags for this question, please edit it the way you find it to be most appropriate. Thanks.

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• How to move the rigidbody at the position of the mouse on release

  - by Edvin

  I'm making a "Can Knockdown" game and I need the rigidbody to move where the player released the mouse(OnMouseUp). Momentarily the Ball moves OnMouseUp because of rigidbody.AddForce(force * factor); and It moves toward the mousePosition but doesn't end up where the mousePosition is. Here's what I have so far in the script. var factor = 20.0; var minSwipeDistY : float; private var startTime : float; private var startPos : Vector3; function OnMouseDown(){ startTime = Time.time; startPos = Input.mousePosition; startPos.z = transform.position.z - Camera.main.transform.position.z; startPos = Camera.main.ScreenToWorldPoint(startPos); } function OnMouseUp(){ var endPos = Input.mousePosition; endPos.z = transform.position.z - Camera.main.transform.position.z; endPos = Camera.main.ScreenToWorldPoint(endPos); var force = endPos - startPos; force.z = force.magnitude; force /= (Time.time - startTime); rigidbody.AddForce(force * factor); }

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• jQuery - upgrade from version 1.6.x to 1.7

  - by Renso

  Goal: Issues to consider when upgrading from jQuery version 1.6 to 1.7. This is a short list and may help identify the real issues you need to concern yourself with in stead of reading through all the release notesSummary of issues encountered during upgrade:As you prepare for upgrade to jQuery 1.7 from 1.6.x, this is a quick glimpse of all the issues that are relevant, not sure if it covers all but may be all you need to worry about.Use this method only for checking checkboxes and radio buttons:$("input:checked")http://api.jquery.com/checked-selector/This will work regardless of the version of jQuery you are using. Note that $("input).attr("checked") returns true prior to jQuery 1.6. Only retrieve "real" attributes with "attr", in order versions it would also retrieve properties like "tagName", this no longer works with jQuery 1.6.1+Why does $("input").attr("checked") no longer (from version 1.6.1+) return TRUE or FALSE, because if you look at the HTML (as well as W3C spec) it does not contain a true/false, but the value checked="checked", which is what it should have returned in the first place. $("input").prop("checked") works, return true, because there is in fact a DOM property for "checked" with the value being "true" or "false".Furthermore, if you want to upgrade to jQuery 1.7 you should only have to worry about this for most part:1. isNumeric() is new, be careful as the older version jQuery.isNaN() has been deprecated2. jqXHR success and error have been deprecated3. When rendering content with text(), white space issue cross-browsers: http://bugs.jquery.com/ticket/3144Other than the issues above I am not aware of any deprecations you need to worry about.Hope this helps to get everyone up to version 1.7

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• Desktop runs very slick, animations are all fast and flawless. Moving windows around, however, is very laggy. Why?

  - by Muu

  This isn't a question about Ubuntu being laggy in general - not at all, in fact, it's very slick and fast for me. Clicking the "Workspace Switcher" in the dock performs the animation immediately and very smoothly. Switching between workspaces with the arrow keys - again, flawlessly. My computer has a resolution of 2560x1440 on a 27" display (no, not an Apple product - though my monitor has the same panel that Apple use in their cinema displays). It's powered by an Nvidia GeForce GTX 470 - easily enough to handle it - and an Intel i3. Hardware is not the issue. I am running Ubuntu 11.10 (upgraded from 11.04). I had the same issue in 11.04. I'm running the "NVIDIA accelerated graphics driver (post-release updates) (version current-updates)" from the additional drivers dialogue. Two drivers have been suggested to me via that dialogue and I've tried both - same effect with each. The driver is "activated and currently in use". Any other information required, let me know and I'll post it. I'm a programmer who works with Linux daily (both as a job and as an interest) so technical instructions are fine. I've noticed that Compiz uses a lot of CPU when moving windows around and it's memory usage is relatively high (though possibly expected for Compiz): 1671 user 20 0 478m 286m 33m S 1 7.3 12:44.05 compiz And one more thing - occasionally moving windows around is fast. But it only happens when all applications are closed, and even then it sometimes doesn't. Something must be interfering, but what? I'll try and find out but in the meantime, any suggestions are much appreciated :-)

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• How come there is still so much programming work?

  - by jd_505

  I wonder why programming jobs haven't yet "dried up" because of the software evolution, for example, I am a developer myself, which means that I do care about software (I mean I am not of the type of guys that needs a computer mainly to just browse the Internet), and still I wouldn't mind if I never receive any more updates on my Ubuntu machine. I find that it provides everything I need, and while the updates provide various bug fixes/improvements, I wouldn't mind using it with its current state for the rest of my life, for 2 years of Ubuntu usage I have never bumped at a serious bug/problem. Another example is Windows, almost half of it's users still use XP, which is practically ancient, yet they find it satisfying all their needs (and I agree with them). I could go with many more examples, but by now you are understanding my point and my question. While new "trends" appears all of the time (like a new mobile OS) which runs on new platforms and requires some fresh development work, still the majority of the software effort goes in to what I consider as "completed projects", or at least a state of a project which is enough to be considered as completed. Do you have an explanation? I can't think of the right tags for this question; please edit it the way you find it to be most appropriate.

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• libapt-inst1.4:i386 fais to install

  - by user92834

  Today I was notifed of updates, some of them being libapt. So I press "Install Updates", and I got this error: The following packages have unmet dependencies: libapt-inst1.4:i386: Depends: libapt-pkg4.12 (>= 0.8.16~exp12ubuntu10.2) but 0.8.16~exp12ubuntu10.3 is installed Depends: libc6 (>= 2.4) but 2.15-0ubuntu10 is installed Depends: libgcc1 (>= 1:4.1.1) but 1:4.6.3-1ubuntu5 is installed Depends: libstdc++6 (>= 4.4.0) but 4.6.3-1ubuntu5 is installed So I open the terminal and typed sudo apt-get install -f I was shown this: The following extra packages will be installed: libapt-inst1.4 libapt-inst1.4:i386 libapt-pkg4.12:i386 The following NEW packages will be installed: libapt-pkg4.12:i386 The following packages will be upgraded: libapt-inst1.4 libapt-inst1.4:i386 2 upgraded, 1 newly installed, 0 to remove and 18 not upgraded. 1 not fully installed or removed. Need to get 0 B/1,146 kB of archives. After this operation, 3,031 kB of additional disk space will be used. Do you want to continue [Y/n]? I selected "yes". And then: E: Internal Error, No file name for libapt-pkg4.12 Also, when I open the software center, I get a message that the database is broken... I'm using 12.04 64bit But why it wants to install the i386 version? I'm using 64 bit ubuntu...

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• a c++ code for scheduling tasks [closed]

  - by scheduling

  This code has no errors but then when i execute it, there is no output and the program automatically shuts down saying the program has stopped working. #include<unistd.h> #include<stdio.h> #include<stdlib.h> #include<time.h> #include<string.h> int main() { char *timetoken; char currtime[7]; char schedtime[7]; int i; struct tm *localtimeptr; strcpy(schedtime,"15:25:00"); while(6!=9) { time_t lt; sleep(1); lt = time(NULL); localtimeptr = localtime(lt); timetoken=strtok(asctime(localtimeptr)," "); for(i=1;i<5;i++) timetoken=strtok('\0'," "); if(i==3) { strcpy(currtime,timetoken); } } printf("The current time is: %s\n",currtime); printf("We are waiting for: %s\n",schedtime); if(!strcmp(currtime,schedtime)) { printf("Time to do stuff \n"); system("C:\PROJECT X"); } getch(); return 0; }

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• ???????????/??????????????????|WebLogic Channel|??????

  - by ???02

  ?WebLogic Server???????????????????――???????WebLogic Server???????????????1???????????????????????????????????·????????????????????2011?11????????Oracle DAB & Developers Days 2011??????????????????????????WebLogic Server???????????????????????????????????????????????/?????????????????????????(???)????????????3??????????????????――??????????????????2????????·????????3??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　???????????????????????????????????????????8?????????????????5???????3??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　??????????300~3,500?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????·????????????????????????????????????????????????????¦???????????·??????????――?????·??????·???????????WebLogic?????　???????????????300??????????????????????????????????????????????????300???????????????????????????????????????????????????????????????????????????????(??????500???)???????????????????????????????????????????????????????????????????·??????????????????????????????????????¦????????????WebLogic Server - ???????·???????????4???????????????????????――????????????　????????????????????????????????????????????????JDBC???????????????????JDBC??????????????????????JDBC?????????????????????????????????????????????????????????　??????????????????????????????????300????????500????????0????????100????????????????????????????????????????????????????????0???????????????????????????????????????????????????????????　?????????????????????????????????????????????????????????JDBC????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????·?????????????????????????????¦?????Pick-Up???????WebLogic Server JDBC???·???????(10.3.4)　?????????????????????????????????????????????????????????????????????????????　??????????????????????????????????????????300?????????????????100???????????????????????????????????????????????????????????????????????????0???????????????????????????????????????????????????????????????????????????????????????????????　????1????1????????????????????????????????????(???????????????)???????????????????????????????????????????????????????????????????　???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????　???????????????????JDBC??????????????????????????????????JDBC???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????·????????????????????????????????????????????????????????????????MBean???????WebLogic Server????????　?????????????????????????????MBean????????????　??????????????MBean??????????????MBean???????????????????PendingUserRequestCount)??????????????????????·?????(ExecuteThreadIdleCount)????·??????????????????????·?????(StandbyThreadCount)?????????????????????·?????????????????(ExecuteThreadTotalCount)??????????????????????????????????????????????????????=????????-??????·??????-?????·????? ?　????????????MBean??????????????MBean???????????????(ActiveConnectionsCurrentCount)?????????????????????????????????????(ActiveConnectionsHighCount)????????????????????????????????????????????????????????????(WaitingForConnectionCurrentCount)?????????????????????????????(WaitingForConnectionHighCount)?????????????????????????????????????????????(?)(WaitSecondsHighCount)????????????????????????????????????　????????????????????????WebLogic Server????????????????????????　???????MBean????????WebLogic Server????????????????????WebLogic Scripting Tool(WLST)?????????????????????????????????????WLST????????????connect('weblogic','welcome1','t3://localhost:7001')import timeimport tracebackserverRuntime()print "Day,Time,State,CurrCapacity,ActiveConnectionsCurrentCount,WaitingForConnectionCurrentCount"while(true): try: oJDBCDataSourceRuntime = getMBean('JDBCServiceRuntime/<????>/JDBCDataSourceRuntimeMBeans/<???????>') oState = oJDBCDataSourceRuntime.getState() oCurrCapacity = oJDBCDataSourceRuntime.getCurrCapacity() oActiveConnectionsCurrentCount = oJDBCDataSourceRuntime.getActiveConnectionsCurrentCount() oWaitingForConnectionCurrentCount = oJDBCDataSourceRuntime.getWaitingForConnectionCurrentCount() print time.strftime('%Y-%m-%d,%H:%M:%S') + "," + str(oState) + "," + str(oCurrCapacity) + "," + str(oActiveConnectionsCurrentCount) + "," + str(oWaitingForConnectionCurrentCount) time.sleep(1) except: print "<<<error>>>" traceback.print_exc() disconnect() break　?????????test.py??????/????????????????$ java weblogic.WLST test.py...?...Day,Time,State,CurrCapacity,ActiveConnectionsCurrentCount,WaitingForConnectionCurrentCount2011-10-31,22:39:01,Running,10,0,02011-10-31,22:39:02,Running,10,0,02011-10-31,22:39:03,Running,12,9,02011-10-31,22:39:04,Running,22,18,02011-10-31,22:39:05,Running,29,15,02011-10-31,22:39:06,Running,29,14,02011-10-31,22:39:07,Running,16,15,02011-10-31,22:39:08,Running,19,15,02011-10-31,22:39:09,Running,19,15,02011-10-31,22:39:10,Running,19,14,02011-10-31,22:39:11,Running,19,15,02011-10-31,22:39:12,Running,19,14,02011-10-31,22:39:13,Running,19,0,0　WLST??????WebLogic Channel?????????·???????! ?WebLogic Scripting Tool????WebLogic Server???/?????????????????????????????????????¦????????·???????! ?WebLogic Scripting Tool????WebLogic Server???/???????¦Oracle DAB & Developers Days 2011????????????????????WebLogic Server??????????????

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• ?????????????????????TCO???????????????????WebLogic???????|WebLogic Channel|??????

  - by ???02

  ????????????/????????????????????????????·???????????????????????????????????????????????????????????WebLogic Server??????(????????)???????????????????????????Oracle Database??????????????????????TCO??????????????????·??????·??????????WebLogic Server???????????????????????(???)???????????????????????????????????????????WebLogic Server?????????????????????????????Oracle Database?????????????????????????????WebLogic Server????????1???Oracle RAC???????????·?????????WebLogic Server??????Oracle Database?????????·??????·?????????????????????????????Oracle Real Application Clusters(RAC)?????????????????????? WebLogic Server???Oracle RAC???????????Active GridLink for RAC???????????????????????Oracle RAC???WebLogic Server?????????????????????????????????Oracle RAC????????????????????????????1?????????????????????????????????????????????????????????????Oracle RAC???"??"?????????????????????????????????·???????????????????????????????????????????????????????·??????????????????????????????????????WebLogic Server?Oracle RAC?????????????????????????Oracle RAC????????????????????????????????WebLogic Server??Oracle RAC????????????????·?????????????????????????????·?????Oracle WebLogic Server?Real Application Clusters? ···?????·???????Oracle WebLogic Server 10.3?????????Oracle RAC?????????????????????????????????????????????????????????????????????????????????????????????????????????????????Oracle WebLogic Server JDBC???·???????Oracle RAC?????????????????????????????????????·????????????????????DB?Oracle Coherence???????????/???????????????????/???????????????????????????????NOSQL?(SQL???????????????/??????????)???????????????????????????·????????????Oracle Coherence???????????????????/??????????????????????? ??Coherence??????????WebLogic Server????1???Coherence?????????·??????????????????"????????"????????????????WebLogic Server?????????????????????O/R?????·?????????Oracle TopLink?????????TopLink?Java???????????????Java Persistence API(JPA)????????JPA?????????????????????TopLink?????Oracle Database????????Coherence?????????????????????? ???WebLogic Server????????????????????Coherence?????????????????????·???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ???????WebLogic Server??Coherence?HTTP????????????????????WebLogic Server????????????????????Coherence????????????????????????????????????????????????????????????WebLogic Server???????????????Coherence?????????????????????????????????????????Coherence???????????????EC??????????·??????????????????????Web?????????????????????????????????????????????????????????????????????·????????????????WebLogic Server?????????1?????Oracle Enterprise Manager????????????????????????????????????Oracle Enterprise Manager(EM)??????????????Oracle EM???????URL???????????????????????????????Oracle Database?????????????????????????????????????"?????"??????TCO??????????????/??????????????????IT?TCO(??????)???????WebLogic Server???????????? ???????????????????????????????????????????????????????????WebLogic Server??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????Oracle EM??????Oracle Database??????????????????????????????????????????????????????????????????TCO????????????? ????Java EE??????????????????????????????????????????TCO????????????????WebLogic Server?????????????????????·????????????????WebLogic Server????????????????????????????IT???????????????????????????WebLogic Server????????????????????????? ???????????????????????????????????????????????JRockit????????????????Sun JVM???????????????WebLogic Server????????Sun JVM????????????????????????????????? ????????????????????????????????????????????????????????????????????? ?????????????????Oracle EM????????????????Oracle EM???????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????Java EE??????????????????????????????????????????????????WebLogic Server?????????????????????????????????????????????????????????????WebLogic Server????????????????????????????WebLogic Server???????????????????????????????????????????????????????????????? ??????TCO???????????????????Java EE???????????????????????????????????????????????"?????"?????????·???????? ??????WebLogic Server??????????????????????·??????·??????????????????????????????????WebLogic Server??????????????????????????????????????????????

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• Advice on my jQuery Ajax Function

  - by NessDan

  So on my site, a user can post a comment on 2 things: a user's profile and an app. The code works fine in PHP but we decided to add Ajax to make it more stylish. The comment just fades into the page and works fine. I decided I wanted to make a function so that I wouldn't have to manage 2 (or more) blocks of codes in different files. Right now, the code is as follows for the two pages (not in a separate .js file, they're written inside the head tags for the pages.): // App page $("input#comment_submit").click(function() { var comment = $("#comment_box").val(); $.ajax({ type: "POST", url: "app.php?id=<?php echo $id; ?>", data: {comment: comment}, success: function() { $("input#comment_submit").attr("disabled", "disabled").val("Comment Submitted!"); $("textarea#comment_box").attr("disabled", "disabled") $("#comments").prepend("<div class=\"comment new\"></div>"); $(".new").prepend("<a href=\"profile.php?username=<?php echo $_SESSION['username']; ?>\" class=\"commentname\"><?php echo $_SESSION['username']; ?></a><p class=\"commentdate\"><?php echo date("M. d, Y", time()) ?> - <?php echo date("g:i A", time()); ?></p><p class=\"commentpost\">" + comment + "</p>").hide().fadeIn(1000); } }); return false; }); And next up, // Profile page $("input#comment_submit").click(function() { var comment = $("#comment_box").val(); $.ajax({ type: "POST", url: "profile.php?username=<?php echo $user; ?>", data: {comment: comment}, success: function() { $("input#comment_submit").attr("disabled", "disabled").val("Comment Submitted!"); $("textarea#comment_box").attr("disabled", "disabled") $("#comments").prepend("<div class=\"comment new\"></div>"); $(".new").prepend("<a href=\"profile.php?username=<?php echo $_SESSION['username']; ?>\" class=\"commentname\"><?php echo $_SESSION['username']; ?></a><p class=\"commentdate\"><?php echo date("M. d, Y", time()) ?> - <?php echo date("g:i A", time()); ?></p><p class=\"commentpost\">" + comment + "</p>").hide().fadeIn(1000); } }); return false; }); Now, on each page the box names will always be the same (comment_box and comment_submit) so what do you guys think of this function (Note, the postComment is in the head tag on the page.): // On the page, (profile.php) $(function() { $("input#comment_submit").click(function() { postComment("profile", "<?php echo $user ?>", "<?php echo $_SESSION['username']; ?>", "<?php echo date("M. d, Y", time()) ?>", "<?php echo date("g:i A", time()); ?>"); }); }); Which leads to this function (which is stored in a separate file called functions.js): function postComment(page, argvalue, username, date, time) { if (page == "app") { var arg = "id"; } if (page == "profile") { var arg = "username"; } var comment = $("#comment_box").val(); $.ajax({ type: "POST", url: page + ".php?" + arg + "=" + argvalue, data: {comment: comment}, success: function() { $("textarea#comment_box").attr("disabled", "disabled") $("input#comment_submit").attr("disabled", "disabled").val("Comment Submitted!"); $("#comments").prepend("<div class=\"comment new\"></div>"); $(".new").prepend("<a href=\"" + page + ".php?" + arg + "=" + username + "\" class=\"commentname\">" + username + "</a><p class=\"commentdate\">" + date + " - " + time + "</p><p class=\"commentpost\">" + nl2br(comment) + "</p>").hide().fadeIn(1000); } }); return false; } That's what I came up with! So, some problems: When I hit the button the page refreshes. What fixed this was taking the return false from the function and putting it into the button click. Any way to keep it in the function and have the same effect? But my real question is this: Can any coders out there that are familiar to jQuery tell me techniques, coding practices, or ways to write my code more efficiently/elegantly? I've done a lot of work in PHP but I know that echoing the date may not be the most efficient way to get the date and time. So any tips that can really help me streamline this function and also make me better with writing jQuery are very welcome!

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• Node.js vs PHP processing speed

  - by Cody Craven

  I've been looking into node.js recently and wanted to see a true comparison of processing speed for PHP vs Node.js. In most of the comparisons I had seen, Node trounced Apache/PHP set ups handily. However all of the tests were small 'hello worlds' that would not accurately reflect any webpage's markup. So I decided to create a basic HTML page with 10,000 hello world paragraph elements. In these tests Node with Cluster was beaten to a pulp by PHP on Nginx utilizing PHP-FPM. So I'm curious if I am misusing Node somehow or if Node is really just this bad at processing power. Note that my results were equivalent outputting "Hello world\n" with text/plain as the HTML, but I only included the HTML as it's closer to the use case I was investigating. My testing box: Core i7-2600 Intel CPU (has 8 threads with 4 cores) 8GB DDR3 RAM Fedora 16 64bit Node.js v0.6.13 Nginx v1.0.13 PHP v5.3.10 (with PHP-FPM) My test scripts: Node.js script var cluster = require('cluster'); var http = require('http'); var numCPUs = require('os').cpus().length; if (cluster.isMaster) { // Fork workers. for (var i = 0; i < numCPUs; i++) { cluster.fork(); } cluster.on('death', function (worker) { console.log('worker ' + worker.pid + ' died'); }); } else { // Worker processes have an HTTP server. http.Server(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write('<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n'); for (var i = 0; i < 10000; i++) { res.write('<p>Hello world</p>\n'); } res.end('</body>\n</html>'); }).listen(80); } This script is adapted from Node.js' documentation at http://nodejs.org/docs/latest/api/cluster.html PHP script <?php echo "<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n"; for ($i = 0; $i < 10000; $i++) { echo "<p>Hello world</p>\n"; } echo "</body>\n</html>"; My results Node.js $ ab -n 500 -c 20 http://speedtest.dev/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Server Hostname: speedtest.dev Server Port: 80 Document Path: / Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 14.603 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95066500 bytes HTML transferred: 95035000 bytes Requests per second: 34.24 [#/sec] (mean) Time per request: 584.123 [ms] (mean) Time per request: 29.206 [ms] (mean, across all concurrent requests) Transfer rate: 6357.45 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 2 Processing: 94 547 405.4 424 2516 Waiting: 0 331 399.3 216 2284 Total: 95 547 405.4 424 2516 Percentage of the requests served within a certain time (ms) 50% 424 66% 607 75% 733 80% 813 90% 1084 95% 1325 98% 1843 99% 2062 100% 2516 (longest request) PHP/Nginx $ ab -n 500 -c 20 http://speedtest.dev/test.php This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: nginx/1.0.13 Server Hostname: speedtest.dev Server Port: 80 Document Path: /test.php Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 0.130 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95109000 bytes HTML transferred: 95035000 bytes Requests per second: 3849.11 [#/sec] (mean) Time per request: 5.196 [ms] (mean) Time per request: 0.260 [ms] (mean, across all concurrent requests) Transfer rate: 715010.65 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 1 Processing: 3 5 0.7 5 7 Waiting: 1 4 0.7 4 7 Total: 3 5 0.7 5 7 Percentage of the requests served within a certain time (ms) 50% 5 66% 5 75% 5 80% 6 90% 6 95% 6 98% 6 99% 6 100% 7 (longest request) Additional details Again what I'm looking for is to find out if I'm doing something wrong with Node.js or if it is really just that slow compared to PHP on Nginx with FPM. I certainly think Node has a real niche that it could fit well, however with these test results (which I really hope I made a mistake with - as I like the idea of Node) lead me to believe that it is a horrible choice for even a modest processing load when compared to PHP (let alone JVM or various other fast solutions). As a final note, I also tried running an Apache Bench test against node with $ ab -n 20 -c 20 http://speedtest.dev/ and consistently received a total test time of greater than 0.900 seconds.

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• matplotlib and python multithread file processing

  - by Napseis

  I have a large number of files to process. I have written a script that get, sort and plot the datas I want. So far, so good. I have tested it and it gives the desired result. Then I wanted to do this using multithreading. I have looked into the doc and examples on the internet, and using one thread in my program works fine. But when I use more, at some point I get random matplotlib error, and I suspect some conflict there, even though I use a function with names for the plots, and iI can't see where the problem could be. Here is the whole script should you need more comment, i'll add them. Thank you. #!/usr/bin/python import matplotlib matplotlib.use('GTKAgg') import numpy as np from scipy.interpolate import griddata import matplotlib.pyplot as plt import matplotlib.colors as mcl from matplotlib import rc #for latex import time as tm import sys import threading import Queue #queue in 3.2 and Queue in 2.7 ! import pdb #the debugger rc('text', usetex=True)#for latex map=0 #initialize the map index. It will be use to index the array like this: array[map,[x,y]] time=np.zeros(1) #an array to store the time middle_h=np.zeros((0,3)) #x phi c #for the middle of the box current_file=open("single_void_cyl_periodic_phi_c_middle_h_out",'r') for line in current_file: if line.startswith('# === time'): map+=1 np.append(time,[float(line.strip('# === time '))]) elif line.startswith('#'): pass else: v=np.fromstring(line,dtype=float,sep=' ') middle_h=np.vstack( (middle_h,v[[1,3,4]]) ) current_file.close() middle_h=middle_h.reshape((map,-1,3)) #3d array: map, x, phi,c ##### def load_and_plot(): #will load a map file, and plot it along with the corresponding profile loaded before while not exit_flag: print("fecthing work ...") #try: if not tasks_queue.empty(): map_index=tasks_queue.get() print("----> working on map: %s" %map_index) x,y,zp=np.loadtxt("single_void_cyl_growth_periodic_post_map_"+str(map_index),unpack=True, usecols=[1, 2,3]) for i,el in enumerate(zp): if el<0.: zp[i]=0. xv=np.unique(x) yv=np.unique(y) X,Y= np.meshgrid(xv,yv) Z = griddata((x, y), zp, (X, Y),method='nearest') figure=plt.figure(num=map_index,figsize=(14, 8)) ax1=plt.subplot2grid((2,2),(0,0)) ax1.plot(middle_h[map_index,:,0],middle_h[map_index,:,1],'*b') ax1.grid(True) ax1.axis([-15, 15, 0, 1]) ax1.set_title('Profiles') ax1.set_ylabel(r'$\phi$') ax1.set_xlabel('x') ax2=plt.subplot2grid((2,2),(1,0)) ax2.plot(middle_h[map_index,:,0],middle_h[map_index,:,2],'*r') ax2.grid(True) ax2.axis([-15, 15, 0, 1]) ax2.set_ylabel('c') ax2.set_xlabel('x') ax3=plt.subplot2grid((2,2),(0,1),rowspan=2,aspect='equal') sub_contour=ax3.contourf(X,Y,Z,np.linspace(0,1,11),vmin=0.) figure.colorbar(sub_contour,ax=ax3) figure.savefig('single_void_cyl_'+str(map_index)+'.png') plt.close(map_index) tasks_queue.task_done() else: print("nothing left to do, other threads finishing,sleeping 2 seconds...") tm.sleep(2) # except: # print("failed this time: %s" %map_index+". Sleeping 2 seconds") # tm.sleep(2) ##### exit_flag=0 nb_threads=2 tasks_queue=Queue.Queue() threads_list=[] jobs=list(range(map)) #each job is composed of a map print("inserting jobs in the queue...") for job in jobs: tasks_queue.put(job) print("done") #launch the threads for i in range(nb_threads): working_bee=threading.Thread(target=load_and_plot) working_bee.daemon=True print("starting thread "+str(i)+' ...') threads_list.append(working_bee) working_bee.start() #wait for all tasks to be treated tasks_queue.join() #flip the flag, so the threads know it's time to stop exit_flag=1 for t in threads_list: print("waiting for threads %s to stop..."%t) t.join() print("all threads stopped")

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• push_back of STL list got bad performance?

  - by Leon Zhang

  I wrote a simple program to test STL list performance against a simple C list-like data structure. It shows bad performance at "push_back()" line. Any comments on it? $ ./test2 Build the type list : time consumed -> 0.311465 Iterate over all items: time consumed -> 0.00898 Build the simple C List: time consumed -> 0.020275 Iterate over all items: time consumed -> 0.008755 The source code is: #include <stdexcept> #include "high_resolution_timer.hpp" #include <list> #include <algorithm> #include <iostream> #define TESTNUM 1000000 /* The test struct */ struct MyType { int num; }; /* * C++ STL::list Test */ typedef struct MyType* mytype_t; void myfunction(mytype_t t) { } int test_stl_list() { std::list<mytype_t> mylist; util::high_resolution_timer t; /* * Build the type list */ t.restart(); for(int i = 0; i < TESTNUM; i++) { mytype_t aItem = (mytype_t) malloc(sizeof(struct MyType)); if(aItem == NULL) { printf("Error: while malloc\n"); return -1; } aItem->num = i; mylist.push_back(aItem); } std::cout << " Build the type list : time consumed -> " << t.elapsed() << std::endl; /* * Iterate over all item */ t.restart(); std::for_each(mylist.begin(), mylist.end(), myfunction); std::cout << " Iterate over all items: time consumed -> " << t.elapsed() << std::endl; return 0; } /* * a simple C list */ struct MyCList; struct MyCList{ struct MyType m; struct MyCList* p_next; }; int test_simple_c_list() { struct MyCList* p_list_head = NULL; util::high_resolution_timer t; /* * Build it */ t.restart(); struct MyCList* p_new_item = NULL; for(int i = 0; i < TESTNUM; i++) { p_new_item = (struct MyCList*) malloc(sizeof(struct MyCList)); if(p_new_item == NULL) { printf("ERROR : while malloc\n"); return -1; } p_new_item->m.num = i; p_new_item->p_next = p_list_head; p_list_head = p_new_item; } std::cout << " Build the simple C List: time consumed -> " << t.elapsed() << std::endl; /* * Iterate all items */ t.restart(); p_new_item = p_list_head; while(p_new_item->p_next != NULL) { p_new_item = p_new_item->p_next; } std::cout << " Iterate over all items: time consumed -> " << t.elapsed() << std::endl; return 0; } int main(int argc, char** argv) { if(test_stl_list() != 0) { printf("ERROR: error at testcase1\n"); return -1; } if(test_simple_c_list() != 0) { printf("ERROR: error at testcase2\n"); return -1; } return 0; }

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• Why does jquery leak memory so badly?

  - by Thomas Lane

  This is kind of a follow-up to a question I posted last week: http://stackoverflow.com/questions/2429056/simple-jquery-ajax-call-leaks-memory-in-ie I love the jquery syntax and all of its nice features, but I've been having trouble with a page that automatically updates table cells via ajax calls leaking memory. So I created two simple test pages for experimenting. Both pages do an ajax call every .1 seconds. After each successful ajax call, a counter is incremented and the DOM is updated. The script stops after 1000 cycles. One uses jquery for both the ajax call and to update the DOM. The other uses the Yahoo API for the ajax and does a document.getElementById(...).innerHTML to update the DOM. The jquery version leaks memory badly. Running in drip (on XP Home with IE7), it starts at 9MB and finishes at about 48MB, with memory growing linearly the whole time. If I comment out the line that updates the DOM, it still finishes at 32MB, suggesting that even simple DOM updates leak a significant amount of memory. The non-jquery version starts and finishes at about 9MB, regardless of whether it updates the DOM. Does anyone have a good explanation of what is causing jquery to leak so badly? Am I missing something obvious? Is there a circular reference that I'm not aware of? Or does jquery just have some serious memory issues? Here is the source for the leaky (jquery) version: <html> <head> <script type="text/javascript" src="http://www.google.com/jsapi"></script> <script type="text/javascript"> google.load('jquery', '1.4.2'); </script> <script type="text/javascript"> var counter = 0; leakTest(); function leakTest() { $.ajax({ url: '/html/delme.x', type: 'GET', success: incrementCounter }); } function incrementCounter(data) { if (counter<1000) { counter++; $('#counter').text(counter); setTimeout(leakTest,100); } else $('#counter').text('finished.'); } </script> </head> <body> <div>Why is memory usage going up?</div> <div id="counter"></div> </body> </html> And here is the non-leaky version: <html> <head> <script type="text/javascript" src="http://yui.yahooapis.com/2.8.0r4/build/yahoo/yahoo-min.js"></script> <script type="text/javascript" src="http://yui.yahooapis.com/2.8.0r4/build/event/event-min.js"></script> <script type="text/javascript" src="http://yui.yahooapis.com/2.8.0r4/build/connection/connection_core-min.js"></script> <script type="text/javascript"> var counter = 0; leakTest(); function leakTest() { YAHOO.util.Connect.asyncRequest('GET', '/html/delme.x', {success:incrementCounter}); } function incrementCounter(o) { if (counter<1000) { counter++; document.getElementById('counter').innerHTML = counter; setTimeout(leakTest,100); } else document.getElementById('counter').innerHTML = 'finished.' } </script> </head> <body> <div>Memory usage is stable, right?</div> <div id="counter"></div> </body> </html>

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• Get the touch position inside the imageview in android

  - by Manikandan

  I have a imageview in my activity and I am able to get the position where the user touch the imageview, through onTouchListener. I placed another image where the user touch over that image. I need to store the touch position(x,y), and use it in another activity, to show the tags. I stored the touch position in the first activity. In the first activity, my imageview at the top of the screen. In the second activity its at the bottom of the screen. If I use the position stored from the first acitvity, it place the tag image at the top, not on the imageview, where I previously clicked in the first activity. Is there anyway to get the position inside the imageview. FirstActivity: cp.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { // TODO Auto-generated method stub Log.v("touched x val of cap img >>", event.getX() + ""); Log.v("touched y val of cap img >>", event.getY() + ""); x = (int) event.getX(); y = (int) event.getY(); tag.setVisibility(View.VISIBLE); int[] viewCoords = new int[2]; cp.getLocationOnScreen(viewCoords); int imageX = x - viewCoords[0]; // viewCoods[0] is the X coordinate int imageY = y - viewCoords[1]; // viewCoods[1] is the y coordinate Log.v("Real x >>>",imageX+""); Log.v("Real y >>>",imageY+""); RelativeLayout rl = (RelativeLayout) findViewById(R.id.lay_lin); ImageView iv = new ImageView(Capture_Image.this); Bitmap bm = BitmapFactory.decodeResource(getResources(), R.drawable.tag_icon_32); iv.setImageBitmap(bm); RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams( RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT); params.leftMargin = x; params.topMargin = y; rl.addView(iv, params); Intent intent= new Intent(Capture_Image.this,Tag_Image.class); Bundle b=new Bundle(); b.putInt("xval", imageX); b.putInt("yval", imageY); intent.putExtras(b); startActivity(intent); return false; } }); In TagImage.java I used the following: im = (ImageView) findViewById(R.id.img_cam22); b=getIntent().getExtras(); xx=b.getInt("xval"); yy=b.getInt("yval"); im.setOnTouchListener(new OnTouchListener() { @Override public boolean onTouch(View v, MotionEvent event) { int[] viewCoords = new int[2]; im.getLocationOnScreen(viewCoords); int imageX = xx + viewCoords[0]; // viewCoods[0] is the X coordinate int imageY = yy+ viewCoords[1]; // viewCoods[1] is the y coordinate Log.v("Real x >>>",imageX+""); Log.v("Real y >>>",imageY+""); RelativeLayout rl = (RelativeLayout) findViewById(R.id.lay_lin); ImageView iv = new ImageView(Tag_Image.this); Bitmap bm = BitmapFactory.decodeResource(getResources(), R.drawable.tag_icon_32); iv.setImageBitmap(bm); RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams( 30, 40); params.leftMargin =imageX ; params.topMargin = imageY; rl.addView(iv, params); return true; } });

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• Simple Constructor With Initializer List? - C++

  - by Alex

  Hi all, below I've included my h file, and my problem is that the compiler is not liking my simple exception class's constructor's with initializer lists. It also is saying that string is undeclared identifier, even though I have #include <string> at the top of the h file. Do you see something I am doing wrong? For further explanation, this is one of my domain classes that I'm integrating into a wxWidgets GUI application on Windows. Thanks! Time.h #pragma once #include <string> #include <iostream> // global constants for use in calculation const int HOURS_TO_MINUTES = 60; const int MINUTES_TO_HOURS = 100; class Time { public: // default Time class constructor // initializes all vars to default values Time(void); // ComputeEndTime computes the new delivery end time // params - none // preconditions - vars will be error-free // postconditions - the correct end time will be returned as an int // returns an int int ComputeEndTime(); // GetStartTime is the getter for var startTime // params - none // returns an int int GetStartTime() { return startTime; } // GetEndTime is the getter for var endTime // params - none // returns an int int GetEndTime() { return endTime; } // GetTimeDiff is the getter for var timeDifference // params - none // returns a double double GetTimeDiff() { return timeDifference; } // SetStartTime is the setter for var startTime // params - an int // returns void void SetStartTime(int s) { startTime = s; } // SetEndTime is the setter for var endTime // params - an int // returns void void SetEndTime(int e) { endTime = e; } // SetTimeDiff is the setter for var timeDifference // params - a double // returns void void SetTimeDiff(double t) { timeDifference = t; } // destructor for Time class ~Time(void); private: int startTime; int endTime; double timeDifference; }; class HourOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type HourOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~HourOutOfRangeException() {} private: string message; }; class MinuteOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type MinuteOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~MinuteOutOfRangeException() {} private: string message; }; class PercentageOutOfRangeException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type PercentageOutOfRangeException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~PercentageOutOfRangeException() {} private: string message; }; class StartEndException { public: // param constructor // initializes message to passed paramater // preconditions - param will be a string // postconditions - message will be initialized // params a string // no return type StartEndException(string pMessage) : message(pMessage) {} // GetMessage is getter for var message // params none // preconditions - none // postconditions - none // returns string string GetMessage() { return message; } // destructor ~StartEndException() {} private: string message; };

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• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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