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Call iconv from Ruby through system()

- by Sebastian

I have a problem with iconv tool. I try to call it from rake file in that way: Dir.glob("*.txt") do |file| system("iconv -f UTF-8 -t 'ASCII//TRANSLIT' #{ file } >> ascii_#{ file }") end But one file is converted partly (size of partialy converted: 10059092 bytes, before convertion: 10081854). Comparing this two files prove that not all content was writen to ASCII. When I call this command explicit from shell it works perfectly. Other smaller files are converted without problems. Is there any limitations on iconv or Ruby's system()?

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Measuring execution time of a system call in C++

- by jm1234567890

I have found some code on measuring execution time here http://www.dreamincode.net/forums/index.php?showtopic=24685 However, it does not seem to work for system calls. I imagine this is because the execution jumps out of the current process. clock_t begin=clock(); system(something); clock_t end=clock(); cout<<"Execution time: "<<diffclock(end,begin)<<" s."<<endl; Then double diffclock(clock_t clock1,clock_t clock2) { double diffticks=clock1-clock2; double diffms=(diffticks)/(CLOCKS_PER_SEC); return diffms; } However this always returns 0 seconds... Is there another method that will work? Also, this is in Linux. Thanks!

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Detect workstation/System Screen Lock using Python(ubuntu)

- by UK

Is there anyway that we can detect when the system/screen gets locked and notify some event to trigger in Ubuntu ?

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PHP exec() and system() functions always return false in IIS

- by Loftx

Hi there, I'm trying to use the PHP exec() or system() (or any other similar function) to run a batch file, but I can't seem to get these to return anything. The simplest example I've seen is this, which outputs nothing: <?php echo system('dir'); ?> The script is running on a windows XP machine on IIS with PHP installed and I've also tried it on my shared hosting account running windows 2003 server/IIS. Can anyone suggest what I need to do to get this working, or provide any commands I can use for troubleshooting? Cheers, Tom

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Sort Grid Columns of mixed type in EXTJS Grid

- by Amit

Hello, I want to sort the extjs columns, I have the column type as float and from the server side i am getting values which can contain "-" value , now what happens the grid is displaying me the NaN value instead of - and the sort is not working anymore. My requirement is to create a custom sort which can sort first based on number and then sort based on string. Thanks to suggest as renderer also not works for me. My Json String is: {metaData:{"totalProperty":"total", "root":"records","fields":[{"header":"Part Number##false","name":"XJE010^VT-007!0","type":"string"},{"header":"Marketing Status##false","name":"STP716^VT-007!0","type":"string"},{"header":"Package##false","name":"XJE016^VT-007!0","type":"string"},{"header":"Automotive Grade##false","name":"STP472^VT-007!0","type":"string"},{"header":"VDSS##false","name":"XJG810^VT-007!0","type":"float"},{"header":"Drain Current (Dc)(I_D) % (A)##false","name":"XJG273^VT-006!0","type":"float"},{"header":"RDS(on) (@VGS=10V) % (Ω)##false","name":"XJG640^VT-006!3","type":"float"},{"header":"Features##false","name":"GNP023^VT-007!0","type":"string"},{"header":"RDS(on) (@4.5 or 5V) % (Ω)##false","name":"XJG640^VT-006!6","type":"float"},{"header":"RDS(on) (@2.7V) % (Ω)##false","name":"XJG640^VT-006!7","type":"float"},{"header":"RDS(on) (@1.8V) % (Ω)##false","name":"XJG640^VT-006!8","type":"float"},{"header":"Free Samples##false","name":"STP0881^VT-007!0","type":"string"},{"header":"Total Gate Charge(Qg) typ ()##true","name":"STP049^VT-002!0","type":"float"},{"header":"Total Power Dissipation(PD) % (W)##true","name":"XJG820^VT-006!0","type":"float"}]},"success":"true", "total":13,"records":[{"XJE010^VT-007!0":"STB80PF55$$/cn/analog/product/67164.jsp","STP716^VT-007!0":"Active","XJE016^VT-007!0":"D2PAK","STP472^VT-007!0":"_","XJG810^VT-007!0":"-55","XJG273^VT-006!0":"80","XJG640^VT-006!3":".018","GNP023^VT-007!0":"-","XJG640^VT-006!6":"-","XJG640^VT-006!7":"-","XJG640^VT-006!8":"-","STP0881^VT-007!0":"No","STP049^VT-002!0":"190","XJG820^VT-006!0":"300"},{"XJE010^VT-007!0":"STD10PF06$$/cn/analog/product/64543.jsp","STP716^VT-007!0":"Active","XJE016^VT-007!0":"IPAK TO-251 TO 252 DPAK","STP472^VT-007!0":"_","XJG810^VT-007!0":"-60","XJG273^VT-006!0":"-10","XJG640^VT-006!3":".2","GNP023^VT-007!0":"-","XJG640^VT-006!6":"-","XJG640^VT-006!7":"-","XJG640^VT-006!8":"-","STP0881^VT-007!0":"No ... Regards, Amit

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How to detect pending system shutdown on Linux?

- by Rajorshi

Hi, I am working on an app where I need to detect system shutdown. However, I have not found any reliable way get a notification on this event. I know that on shutdown, my app will receive a SIGTERM signal followed by a SIGKILL. What I want to know is if there is someway to query if a SIGTERM is part of a shutdown sequence? Does any one know if there is a way to query that programmatically (C API)? As far as I know, the system does not provide any other method to query for an impending shutdowm. If it does, that would solve my problem as well. I have been trying out runlevels as well, but change in runlevels seem to be instantaneous and without any prior warnings.

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Issuing native system commands in Scala

- by Tony

I want to issue a native system command from a Scala program, and perhaps trap the output. ("ls" comes to mind. There may be other ways to get directory information without issuing the command, but that's beside the point of my question.) It would correspond to os.system(...) in Python. I've looked in "Programming in Scala". I've looked in O'Reilly's "Programming Scala". I've Googled several combinations of terms. No luck yet. Can someone out there give me an example, or point me at a resource where I can find an example?

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HOW TO understand the programmming of operation system..!!!

- by piemesons

Hello, I want to learn the operating system. How it works. I dont want to make my own operating system. I just want to learn how it works. As i can find out source code of any open source OS. But how to start. Like stating from the first elementary kernal(what ever it is). Some body suggested me try to implement linux from scratch.etc etc.Please guide me in a proper way. i want to know about the proper path to follow. I am ready to invest three four years just to understand the basics. I am having good fundamentals of c c++,php, Oops, compiler design

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Killing a script launched in a Process via os.system()

- by L.J.

I have a python script which launches several processes. Each process basically just calls a shell script: from multiprocessing import Process import os import logging def thread_method(n = 4): global logger command = "~/Scripts/run.sh " + str(n) + " >> /var/log/mylog.log" if (debug): logger.debug(command) os.system(command) I launch several of these threads, which are meant to run in the background. I want to have a timeout on these threads, such that if it exceeds the timeout, they are killed: t = [] for x in range(10): try: t.append(Process(target=thread_method, args=(x,) ) ) t[-1].start() except Exception as e: logger.error("Error: unable to start thread") logger.error("Error message: " + str(e)) logger.info("Waiting up to 60 seconds to allow threads to finish") t[0].join(60) for n in range(len(t)): if t[n].is_alive(): logger.info(str(n) + " is still alive after 60 seconds, forcibly terminating") t[n].terminate() The problem is that calling terminate() on the process threads isn't killing the launched run.sh script - it continues running in the background until I either force kill it from the command line, or it finishes internally. Is there a way to have terminate also kill the subshell created by os.system()?

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System.Net.WebClient Class in .Net CompactFramework 3.5 ?

- by Leen15

Hi at all! I need to comunicate with a Server that give me async answers (streamer connection). I find this: http://msdn.microsoft.com/en-en/library/ms144211%28v=VS.80%29.aspx that generate this event: http://msdn.microsoft.com/en-en/library/system.net.webclient.openreadcompleted%28v=VS.80%29.aspx I think this is what i need, but i don't have the WebClient class in my System.Net of CompactFramework 3.5. How can i do? Thanks. EDIT: I've done a more clear question: httpRequest, httpResponse, send GET through Stream and Receive the Result in C#

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pthreads recursively calling system command and segfault appears

- by jess

I have a code base where i am creating 8 threads and each thread just calls system command to display date in a continuous cycle, as shown below: void * system_thread(void *arg) { int cpu = (int)arg; printf("thread : start %d\n", cpu); for (;;) { // date ã³ãã³ãã®å®è¡ if (mode == 0) { system("date"); } else { f_hfp_nlc_Fsystem("date"); } } sleep(timerval); return NULL; } This application segfaults after running for 2-3 seconds, due to following 2 reasons: 1. read access, where the address is out of VM area 2. write acces, where it does not of write permission and its trying to modify some structure.

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difference between system.out and system.err

- by sap

As i know both out and err are of same class printstream then can anybody tell me how they differe...how they changed there behaviour

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DotNet Get User Operating System (HTTP_USER_AGENT)

- by rockinthesixstring

I'm looking at building an exhaustive function that returns a friendly name for the Users Operating System. I think I have most of the Windows stuff down, but I'm not sure about Linux, OSX, and others. Does anyone know where I can find an exhaustive list of HTTP_USER_AGENT's 'Gets the users operating system Public Shared Function GetUserOS() As String Dim strAgent As String = HttpContext.Current.Request.ServerVariables("HTTP_USER_AGENT") 'Windows OS's If InStr(strAgent, "Windows NT 6.1") Then : Return "Windows 7" ElseIf InStr(strAgent, "Windows NT 6.0") Then : Return "Windows Vista" ElseIf InStr(strAgent, "Windows NT 5.2") Then : Return "Windows Server 2003" ElseIf InStr(strAgent, "Windows NT 5.1") Then : Return "Windows XP" ElseIf InStr(strAgent, "Windows NT 5.0") Then : Return "Windows 2000" ElseIf InStr(strAgent, "Windows 98") Then : Return "Windows 98" ElseIf InStr(strAgent, "Windows 95") Then : Return "Windows 95" 'Mac OS's ElseIf InStr(strAgent, "Mac OS X") Then : Return "Mac OS X" 'Linux OS's ElseIf InStr(strAgent, "Linux") Then : Return "Linux" Else : Return "Unknown" End If End Function 'GetUserOS

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How to understand the programming of an operating system

- by piemesons

Hello, I want to learn the operating system. How it works. I don't want to make my own operating system. I just want to learn how it works. As I can find out source code of any open source OS. But how to start. Like starting from the first elementary kernel (whatever it is). Somebody suggested I try to implement Linux from scratch etc. Please guide me in a proper way. I want to know about the proper path to follow. I am ready to invest three to four years just to understand the basics. I have good fundamentals of C, C++, PHP, OOP and compiler design.

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Getting input in system() function (Mac)

- by Alex

#include <iostream> using namespace std; int main() { short int enterVal; cout << "enter a number to say: " << endl; cin >> enterVal; system("say "%d"") << enterVal; return 0; } Is what I am currently trying. I want the user to enter a number and the system() function says it basically. The code above has an error which says " 'd' was not declared in this scope ". Thanks in advance.

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Creating an email notification system based on polling database rows

- by Ashish Sharma

I have to design an email notification system based on the following requirements: The email notifications would be created based on polling rows in a Mysql 5.5 DB table when they are in a particular 'Completed' state. The email notification should be sent out in no more than 5 minutes from the time the row was created in the DB table (At the time of DB table row creation the state of the row might not be 'Completed'). Once 5 minutes for the DB table row expire in reaching the 'Completed' state, separate email notification need to be sent (basically telling the user that the original email notification would be delayed) and then sending the email notification as and when the row state reaches to being 'Completed'. The rest of the system requirements are : Adding relevant checks to monitor the whole system via MBeans interface. The system should be scalable so that if the rate of DB table rows creation increases so does the Email notification system be able to ramp up. So I request suggestions on following lines: What approach should I take in solving the problem described from a programming/Design pattern point of view? Suggestion for any third party plugin/software that can be used to solve the problem described? Points to take care regarding scalability and monitoring the health of the system? Java is the language of preference but I am open to using off the shelf components that can be interfaced with Java language or provide standard ports for communication. Currently I do have an in house grown system (written in Java) that is catering to the specified requirements, but it's now crumbling under increased load and now I want to give the problem a fresh look. thanks in advance Ashish

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Bootloader error Ubuntu 12.04, system goes to Grub-rescue instead of booting

- by user83508

I am trying to install ubuntu 12.04 on my system but it is constantly giving me bootloader install fail error. I have tried to lot to solve this issue but reading articles over the internet but still no gain. Firstly since the bootloader was not getting installed I tried to install it on all the alternative paths given in the installer, failing with I selected install ubuntu without bootloader. Then I tried to manually install bootloader via terminal at try ubuntu via grub-install, but I was not able to do that. Then I tried using boot-repair and it was also not able to install the bootloader because after it my system shows grub-rescue. I tried to use boot-repair and install bootloader on a seperate partition mounted to /boot and still my system is booting and it still shows grub-rescue. The error which my system shows during boot is: Error : no such device : 04ac0510-bd4f-43b8-b885-b885-11c4dec21db8 I am not dual booting and ubuntu is the only OS I am installing. I am using Raid 0 with two blue western digital hard drive so I am not sure whether it is right or not. The details given by boot-repair are in the below mentioned link; http://paste.ubuntu.com/1147208/ Afterwards, I made one more change I installed ubuntu again and this time I installed the bootloader at a different partition on /boot. After this the bootloader error has gone but I am still not able to boot to ubuntu as I get the same error I was getting before. I have not installed dmraid, I feel it is neccessary for Raid0, but I thought ubuntu already has Raid drivers. Moreover in the dmraid installation instructions for 12.04, I used the one for 10.04 and selected to install bootloader at the partitions from the dropdown. This time the installation finished normally without an error but still I am not able to boot my system as the same error shows during booting this time also. Now I am stucked and I have no clue on how I can boot my system. Please tell me how can I boot my system.

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System testing - making sure the system conforms to specification. Validation?

- by user970696

After weeks of research I have nearly completed my thesis, yet I am unable to clear up my confusion contained in all previous threads here (and in many books): During system testing, we check the system function against system analysis (functional system design) - but that would fit to a definition of verification according to many books. But I follow ISO12207, which considers all testing as validation (making sure work product meets requirement for intended use). How can I justify that unit testing or system testing is validation, even though when I check it against specification? Which fullfils the definiton of verification? When testing that e.g. "Save button" works, is it validation? This picture shows my understanding of V&V, so different from many other sources, including ISTQB etc. Essential problem I have is that a book using the same picture also states on another place that: test activities in the area of validation are usability, alpha and beta testing. For verification, testable system requirements are defined whose correct implementation can be tested through system tests. Isn't that the opposite of what the picture says? Most books present the following picture, where validation is just making sure that customer needs are satisfied. Mind you that according to ISO, validation activity is testing.

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Web migration of a VB6 system with VWG

- by Webgui

Brinks Bolivia eSAC System (Customer Service) allows to register all different kinds of contacts for a customer; addition to maintaining an updated status of each service or customer request, to have accurate information and perform the appropriate procedures for all applications. The system was originally developed in VB6 and since web access was essential it was offered via Citrix. Since the application's performance was a critical issue as well as the need to offer the system without specific installations the company looked for a solution that would solve those drawbacks of using Citrix. Searching for a solution that would allow it to offer the eSAC system over the web without the need for specific client installations and provide sufficient performance levels even when there is limited bandwidth lead Brinks to a decision to migrate their VB6 Customer Service system to to Visual WebGui. "Developing on Visual WebGui we were able to migrate the system to web environment and even add new features in less time which allows us to offer it over a standard web browser with better performance and no installations as was required with Citrix," concluded Alexander Cuellar. The full article and screenshots of the system are available here.

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Can't start system due to mdadm failing

- by user101212

I used to have a 5-disk RAID5 partition, all working very well. I have then decided to add 3 more disks on it, totaling 8 equal disks. I've opened Webmin and just asked to add the disks. Then I've realized the three disks had NTFS partitions, wich mdadm didn't complain, so I tried to stop the growing to remove the Windows partitions. I've tried to remove a disk using the same Webmin, but (as you might guess and call me fool...), the system became unstable. By restarting the system, I've started receiving these messages: "udev[126]: timeout: killing '/sbin/mdadm --incremental /dev/sdh1' [311]" "udev[124]: timeout: killing '/sbin/mdadm --detail --export /dev/md0' [316]" I've formated the system disk, hoping to get a system up and running. I did that with all RAID disks disconected, so everything was fine. I then reconnected the disks, wich was also ok. And finally installed mdadm using apt-get. By reboot, the system has found the mdadm intention of growing the system, so the same messages appear again. I other words: I can't even reach a command prompt to do something. Any ideas of what to do? I believe I could turn off the system, disconnect the disks and look for the mdadm.conf file. Would that be a good idead? I'm no Linux expert, so I'm really lost here.

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SQL SERVER – PAGELATCH_DT, PAGELATCH_EX, PAGELATCH_KP, PAGELATCH_SH, PAGELATCH_UP – Wait Type – Day 12 of 28

- by pinaldave

This is another common wait type. However, I still frequently see people getting confused with PAGEIOLATCH_X and PAGELATCH_X wait types. Actually, there is a big difference between the two. PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal] The difference between locks and latches is that locks seal all the involved resources throughout the duration of the transactions (and other processes will have no access to the object), whereas latches locks the resources during the time when the data is changed. This way, a latch is able to maintain the integrity of the data between storage engine and data cache. A latch is a short-living lock that is put on resources on buffer cache and in the physical disk when data is moved in either directions. As soon as the data is moved, the latch is released. Now, let us understand the wait stat type related to latches. From Book On-Line: PAGELATCH_DT Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode. PAGELATCH_EX Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode. PAGELATCH_KP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode. PAGELATCH_SH Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode. PAGELATCH_UP Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode. PAGELATCH_X Explanation: When there is a contention of access of the in-memory pages, this wait type shows up. It is quite possible that some of the pages in the memory are of very high demand. For the SQL Server to access them and put a latch on the pages, it will have to wait. This wait type is usually created at the same time. Additionally, it is commonly visible when the TempDB has higher contention as well. If there are indexes that are heavily used, contention can be created as well, leading to this wait type. Reducing PAGELATCH_X wait: The following counters are useful to understand the status of the PAGELATCH: Average Latch Wait Time (ms): The wait time for latch requests that have to wait. Latch Waits/sec: This is the number of latch requests that could not be granted immediately. Total Latch Wait Time (ms): This is the total latch wait time for latch requests in the last second. If there is TempDB contention, I suggest that you read the blog post of Robert Davis right away. He has written an excellent blog post regarding how to find out TempDB contention. The same blog post explains the terms in the allocation of GAM, SGAM and PFS. If there was a TempDB contention, Paul Randal explains the optimal settings for the TempDB in his misconceptions series. Trace Flag 1118 can be useful but use it very carefully. I totally understand that this blog post is not as clear as my other blog posts. I suggest if this wait stats is on one of your higher wait type. Do leave a comment or send me an email and I will get back to you with my solution for your situation. May the looking at all other wait stats and types together become effective as this wait type can help suggest proper bottleneck in your system. Read all the post in the Wait Types and Queue series. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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A simple Dynamic Proxy

- by Abhijeet Patel

Frameworks such as EF4 and MOQ do what most developers consider "dark magic". For instance in EF4, when you use a POCO for an entity you can opt-in to get behaviors such as "lazy-loading" and "change tracking" at runtime merely by ensuring that your type has the following characteristics: The class must be public and not sealed. The class must have a public or protected parameter-less constructor. The class must have public or protected properties Adhere to this and your type is magically endowed with these behaviors without any additional programming on your part. Behind the scenes the framework subclasses your type at runtime and creates a "dynamic proxy" which has these additional behaviors and when you navigate properties of your POCO, the framework replaces the POCO type with derived type instances. The MOQ framework does simlar magic. Let's say you have a simple interface: public interface IFoo { int GetNum(); } We can verify that the GetNum() was invoked on a mock like so: var mock = new Mock<IFoo>(MockBehavior.Default); mock.Setup(f => f.GetNum()); var num = mock.Object.GetNum(); mock.Verify(f => f.GetNum()); Beind the scenes the MOQ framework is generating a dynamic proxy by implementing IFoo at runtime. the call to moq.Object returns the dynamic proxy on which we then call "GetNum" and then verify that this method was invoked. No dark magic at all, just clever programming is what's going on here, just not visible and hence appears magical! Let's create a simple dynamic proxy generator which accepts an interface type and dynamically creates a proxy implementing the interface type specified at runtime. public static class DynamicProxyGenerator { public static T GetInstanceFor<T>() { Type typeOfT = typeof(T); var methodInfos = typeOfT.GetMethods(); AssemblyName assName = new AssemblyName("testAssembly"); var assBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assName, AssemblyBuilderAccess.RunAndSave); var moduleBuilder = assBuilder.DefineDynamicModule("testModule", "test.dll"); var typeBuilder = moduleBuilder.DefineType(typeOfT.Name + "Proxy", TypeAttributes.Public); typeBuilder.AddInterfaceImplementation(typeOfT); var ctorBuilder = typeBuilder.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, new Type[] { }); var ilGenerator = ctorBuilder.GetILGenerator(); ilGenerator.EmitWriteLine("Creating Proxy instance"); ilGenerator.Emit(OpCodes.Ret); foreach (var methodInfo in methodInfos) { var methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, MethodAttributes.Public | MethodAttributes.Virtual, methodInfo.ReturnType, methodInfo.GetParameters().Select(p => p.GetType()).ToArray() ); var methodILGen = methodBuilder.GetILGenerator(); methodILGen.EmitWriteLine("I'm a proxy"); if (methodInfo.ReturnType == typeof(void)) { methodILGen.Emit(OpCodes.Ret); } else { if (methodInfo.ReturnType.IsValueType || methodInfo.ReturnType.IsEnum) { MethodInfo getMethod = typeof(Activator).GetMethod(/span>"CreateInstance",new Type[]{typeof((Type)}); LocalBuilder lb = methodILGen.DeclareLocal(methodInfo.ReturnType); methodILGen.Emit(OpCodes.Ldtoken, lb.LocalType); methodILGen.Emit(OpCodes.Call, typeofype).GetMethod("GetTypeFromHandle")); )); methodILGen.Emit(OpCodes.Callvirt, getMethod); methodILGen.Emit(OpCodes.Unbox_Any, lb.LocalType); } else { methodILGen.Emit(OpCodes.Ldnull); } methodILGen.Emit(OpCodes.Ret); } typeBuilder.DefineMethodOverride(methodBuilder, methodInfo); } Type constructedType = typeBuilder.CreateType(); var instance = Activator.CreateInstance(constructedType); return (T)instance; } } Dynamic proxies are created by calling into the following main types: AssemblyBuilder, TypeBuilder, Modulebuilder and ILGenerator. These types enable dynamically creating an assembly and emitting .NET modules and types in that assembly, all using IL instructions. Let's break down the code above a bit and examine it piece by piece Type typeOfT = typeof(T); var methodInfos = typeOfT.GetMethods(); AssemblyName assName = new AssemblyName("testAssembly"); var assBuilder = AppDomain.CurrentDomain.DefineDynamicAssembly(assName, AssemblyBuilderAccess.RunAndSave); var moduleBuilder = assBuilder.DefineDynamicModule("testModule", "test.dll"); var typeBuilder = moduleBuilder.DefineType(typeOfT.Name + "Proxy", TypeAttributes.Public); We are instructing the runtime to create an assembly caled "test.dll"and in this assembly we then emit a new module called "testModule". We then emit a new type definition of name "typeName"Proxy into this new module. This is the definition for the "dynamic proxy" for type T typeBuilder.AddInterfaceImplementation(typeOfT); var ctorBuilder = typeBuilder.DefineConstructor( MethodAttributes.Public, CallingConventions.Standard, new Type[] { }); var ilGenerator = ctorBuilder.GetILGenerator(); ilGenerator.EmitWriteLine("Creating Proxy instance"); ilGenerator.Emit(OpCodes.Ret); The newly created type implements type T and defines a default parameterless constructor in which we emit a call to Console.WriteLine. This call is not necessary but we do this so that we can see first hand that when the proxy is constructed, when our default constructor is invoked. var methodBuilder = typeBuilder.DefineMethod( methodInfo.Name, MethodAttributes.Public | MethodAttributes.Virtual, methodInfo.ReturnType, methodInfo.GetParameters().Select(p => p.GetType()).ToArray() ); We then iterate over each method declared on type T and add a method definition of the same name into our "dynamic proxy" definition if (methodInfo.ReturnType == typeof(void)) { methodILGen.Emit(OpCodes.Ret); } If the return type specified in the method declaration of T is void we simply return. if (methodInfo.ReturnType.IsValueType || methodInfo.ReturnType.IsEnum) { MethodInfo getMethod = typeof(Activator).GetMethod("CreateInstance", new Type[]{typeof(Type)}); LocalBuilder lb = methodILGen.DeclareLocal(methodInfo.ReturnType); methodILGen.Emit(OpCodes.Ldtoken, lb.LocalType); methodILGen.Emit(OpCodes.Call, typeof(Type).GetMethod("GetTypeFromHandle")); methodILGen.Emit(OpCodes.Callvirt, getMethod); methodILGen.Emit(OpCodes.Unbox_Any, lb.LocalType); } If the return type in the method declaration of T is either a value type or an enum, then we need to create an instance of the value type and return that instance the caller. In order to accomplish that we need to do the following: 1) Get a handle to the Activator.CreateInstance method 2) Declare a local variable which represents the Type of the return type(i.e the type object of the return type) specified on the method declaration of T(obtained from the MethodInfo) and push this Type object onto the evaluation stack. In reality a RuntimeTypeHandle is what is pushed onto the stack. 3) Invoke the "GetTypeFromHandle" method(a static method in the Type class) passing in the RuntimeTypeHandle pushed onto the stack previously as an argument, the result of this invocation is a Type object (representing the method's return type) which is pushed onto the top of the evaluation stack. 4) Invoke Activator.CreateInstance passing in the Type object from step 3, the result of this invocation is an instance of the value type boxed as a reference type and pushed onto the top of the evaluation stack. 5) Unbox the result and place it into the local variable of the return type defined in step 2 methodILGen.Emit(OpCodes.Ldnull); If the return type is a reference type then we just load a null onto the evaluation stack methodILGen.Emit(OpCodes.Ret); Emit a a return statement to return whatever is on top of the evaluation stack(null or an instance of a value type) back to the caller Type constructedType = typeBuilder.CreateType(); var instance = Activator.CreateInstance(constructedType); return (T)instance; Now that we have a definition of the "dynamic proxy" implementing all the methods declared on T, we can now create an instance of the proxy type and return that out typed as T. The caller can now invoke the generator and request a dynamic proxy for any type T. In our example when the client invokes GetNum() we get back "0". Lets add a new method on the interface called DayOfWeek GetDay() public interface IFoo { int GetNum(); DayOfWeek GetDay(); } When GetDay() is invoked, the "dynamic proxy" returns "Sunday" since that is the default value for the DayOfWeek enum This is a very trivial example of dynammic proxies, frameworks like MOQ have a way more sophisticated implementation of this paradigm where in you can instruct the framework to create proxies which return specified values for a method implementation.

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Windows 7 Not Starting and System Repair Not Loading

- by Mark

I have a Dell Inspiron 1545 running Windows 7 When turning on my PC I keep receiving a black screen with the option to use System Repair or Start Normally. Both options lead me to the System Repair background except no matter how long I wait the system restore options never show up. Choosing F8 and running all of the options including safe mode encounters the same result above. I tried to to use 2 system recovery disks 32x and 64x I downloaded and both lead to similiar results. When I choose System Repair running from the disk the System Repair Question asking to select a language pops ups but after this no matter how long I wait no other options appear. Next after restarting and selecting F8 (after hitting f12 and running from CD) I choose 'Run From Safe Mode with Command Prompt' I am able to run all of the options from System Restore with differing results: Startup Repair: Choosing this ends up in system repair indefinitely (left running 12 hrs) System Restore: Does Nothing. PC thinks for a second and then stops. When selecting ShutDown I see an error message stating there are no restore points. System Image Recovery: Service Cannot be started in Safe Mode Windows Memory Diagnostic: Runs test but then leads to system repair background which never loads system repair Command Prompt: chkdsk /r -Cannot Lock Current Drive...write protected. chkdsk /f -Cannot Lock Current Drive...write protected. bootcfg - Cannot open Boot.Ini file bootcfg - Ran all 3 (rebuildBcd, FixMbr and Fixboot) but PC still goes to System Repair background with no repair options popping up upon restart (without recovery CD). I'm on the verge of purchasing a boot utility disk for $50 unless there is anything else short of "take it to a computer shop" that somebody can suggest I try.

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JPRT: A Build & Test System

- by kto

DRAFT A while back I did a little blogging on a system called JPRT, the hardware used and a summary on my java.net weblog. This is an update on the JPRT system. JPRT ("JDK Putback Reliablity Testing", but ignore what the letters stand for, I change what they mean every day, just to annoy people :\^) is a build and test system for the JDK, or any source base that has been configured for JPRT. As I mentioned in the above blog, JPRT is a major modification to a system called PRT that the HotSpot VM development team has been using for many years, very successfully I might add. Keeping the source base always buildable and reliable is the first step in the 12 steps of dealing with your product quality... or was the 12 steps from Alcoholics Anonymous... oh well, anyway, it's the first of many steps. ;\^) Internally when we make changes to any part of the JDK, there are certain procedures we are required to perform prior to any putback or commit of the changes. The procedures often vary from team to team, depending on many factors, such as whether native code is changed, or if the change could impact other areas of the JDK. But a common requirement is a verification that the source base with the changes (and merged with the very latest source base) will build on many of not all 8 platforms, and a full 'from scratch' build, not an incremental build, which can hide full build problems. The testing needed varies, depending on what has been changed. Anyone that was worked on a project where multiple engineers or groups are submitting changes to a shared source base knows how disruptive a 'bad commit' can be on everyone. How many times have you heard: "So And So made a bunch of changes and now I can't build!". But multiply the number of platforms by 8, and make all the platforms old and antiquated OS versions with bizarre system setup requirements and you have a pretty complicated situation (see http://download.java.net/jdk6/docs/build/README-builds.html). We don't tolerate bad commits, but our enforcement is somewhat lacking, usually it's an 'after the fact' correction. Luckily the Source Code Management system we use (another antique called TeamWare) allows for a tree of repositories and 'bad commits' are usually isolated to a small team. Punishment to date has been pretty drastic, the Queen of Hearts in 'Alice in Wonderland' said 'Off With Their Heads', well trust me, you don't want to be the engineer doing a 'bad commit' to the JDK. With JPRT, hopefully this will become a thing of the past, not that we have had many 'bad commits' to the master source base, in general the teams doing the integrations know how important their jobs are and they rarely make 'bad commits'. So for these JDK integrators, maybe what JPRT does is keep them from chewing their finger nails at night. ;\^) Over the years each of the teams have accumulated sets of machines they use for building, or they use some of the shared machines available to all of us. But the hunt for build machines is just part of the job, or has been. And although the issues with consistency of the build machines hasn't been a horrible problem, often you never know if the Solaris build machine you are using has all the right patches, or if the Linux machine has the right service pack, or if the Windows machine has it's latest updates. Hopefully the JPRT system can solve this problem. When we ship the binary JDK bits, it is SO very important that the build machines are correct, and we know how difficult it is to get them setup. Sure, if you need to debug a JDK problem that only shows up on Windows XP or Solaris 9, you'll still need to hunt down a machine, but not as a regular everyday occurance. I'm a big fan of a regular nightly build and test system, constantly verifying that a source base builds and tests out. There are many examples of automated build/tests, some that trigger on any change to the source base, some that just run every night. Some provide a protection gateway to the 'golden' source base which only gets changes that the nightly process has verified are good. The JPRT (and PRT) system is meant to guard the source base before anything is sent to it, guarding all source bases from the evil developer, well maybe 'evil' isn't the right word, I haven't met many 'evil' developers, more like 'error prone' developers. ;\^) Humm, come to think about it, I may be one from time to time. :\^{ But the point is that by spreading the build up over a set of machines, and getting the turnaround down to under an hour, it becomes realistic to completely build on all platforms and test it, on every putback. We have the technology, we can build and rebuild and rebuild, and it will be better than it was before, ha ha... Anybody remember the Six Million Dollar Man? Man, I gotta get out more often.. Anyway, now the nightly build and test can become a 'fetch the latest JPRT build bits' and start extensive testing (the testing not done by JPRT, or the platforms not tested by JPRT). Is it Open Source? No, not yet. Would you like to be? Let me know. Or is it more important that you have the ability to use such a system for JDK changes? So enough blabbering on about this JPRT system, tell me what you think. And let me know if you want to hear more about it or not. Stay tuned for the next episode, same Bloody Bat time, same Bloody Bat channel. ;\^) -kto

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How can I see the system and contents files for the Ipad?

- by ahmed

Hello I want to see the system files for the Apple ipad in my computer but the problem is when I plug the Ipad to my windows 7 PC the windows open the Ipad as a storage which has only some wallpapers - i cant see any system files - my question is how can I see the system and contents files for the Ipad? because I want to do some modification on the system files to change one of the Ipad keyboards to support my language Thanks

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