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Automated Oracle Schema Migration Tool

- by Dave Jarvis

What are some tools (commercial or OSS) that provide a GUI-based mechanism for creating schema upgrade scripts? To be clear, here are the tool responsibilities: Obtain connection to recent schema version (called "source"). Obtain connection to previous schema version (called "target"). Compare all schema objects between source and target. Create a script to make the target schema equivalent to the source schema ("upgrade script"). Create a rollback script to revert the source schema, used if the upgrade script fails (at any point). Create individual files for schema objects. The software must: Use ALTER TABLE instead of DROP and CREATE for renamed columns. Work with Oracle 10g or greater. Create scripts that can be batch executed (via command-line). Trivial installation process. (Bonus) Create scripts that can be executed with SQL*Plus. Here are some examples (from StackOverflow, ServerFault, and Google searches): Change Manager Oracle SQL Developer Software that does not meet the criteria, or cannot be evaluated, includes: TOAD PL/SQL Developer - Invalid SQL*Plus statements. Does not produce ALTER statements. SQL Fairy - No installer. Complex installation process. Poorly documented. DBDiff - Crippled data set evaluation, poor customer support. OrbitDB - Crippled data set evaluation. SchemaCrawler - No easily identifiable download version for Oracle databases. SQL Compare - SQL Server, not Oracle. LiquiBase - Requires changing the development process. No installer. Manually edit config files. Does not recognize its own baseUrl parameter. The only acceptable crippling of the evaluation version is by time. Crippling by restricting the number of tables and views hides possible bugs that are only visible in the software during the attempt to migrate hundreds of tables and views.

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proper use of volatile keyword

- by luke

I think i have a pretty good idea about the volatile keyword in java, but i'm thinking about re-factoring some code and i thought it would be a good idea to use it. i have a class that is basically working as a DB Cache. it holds a bunch of objects that it has read from a database, serves requests for those objects, and then occasionally refreshes the database (based on a timeout). Heres the skeleton public class Cache { private HashMap mappings =....; private long last_update_time; private void loadMappingsFromDB() { //.... } private void checkLoad() { if(System.currentTimeMillis() - last_update_time > TIMEOUT) loadMappingsFromDB(); } public Data get(ID id) { checkLoad(); //.. look it up } } So the concern is that loadMappingsFromDB could be a high latency operation and thats not acceptable, So initially i thought that i could spin up a thread on cache startup and then just have it sleep and then update the cache in the background. But then i would need to synchronize my class (or the map). and then i would just be trading an occasional big pause for making every cache access slower. Then i thought why not use volatile i could define the map reference as volatile private volatile HashMap mappings =....; and then in get (or anywhere else that uses the mappings variable) i would just make a local copy of the reference: public Data get(ID id) { HashMap local = mappings; //.. look it up using local } and then the background thread would just load into a temp table and then swap the references in the class HashMap tmp; //load tmp from DB mappings = tmp;//swap variables forcing write barrier Does this approach make sense? and is it actually thread-safe?

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Solving Naked Triples in Sudoku

- by Kave

Hello, I wished I paid more attention to the math classes back in Uni. :) How do I implement this math formula for naked triples? Naked Triples Take three cells C = {c1, c2, c3} that share a unit U. Take three numbers N = {n1, n2, n3}. If each cell in C has as its candidates ci ? N then we can remove all ni ? N from the other cells in U.** I have a method that takes a Unit (e.g. a Box, a row or a column) as parameter. The unit contains 9 cells, therefore I need to compare all combinations of 3 cells at a time that from the box, perhaps put them into a stack or collection for further calculation. Next step would be taking these 3-cell-combinations one by one and compare their candidates against 3 numbers. Again these 3 numbers can be any possible combination from 1 to 9. Thats all I need. But how would I do that? How many combinations would I get? Do I get 3 x 9 = 27 combinations for cells and then the same for numbers (N)? How would you solve this in classic C# loops? No Lambda expression please I am already confused enough :) Many Thanks for any help,

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Traceroute comparison and statistics

- by ben-casey

I have a number of traceroutes that i need to compare against each other but i dont know the best way to do it, ive been told that hash maps are a good technique but i dont know how to implement them on my code. so far i have: FileInputStream fstream = new FileInputStream("traceroute.log"); // Get the object of DataInputStream DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; // reads lines in while ((strLine = br.readLine()) != null) { System.out.println(strLine); } and the output looks like this: Wed Mar 31 01:00:03 BST 2010 traceroute to www.bbc.co.uk (212.58.251.195), 30 hops max, 40 byte packets 1 139.222.0.1 (139.222.0.1) 0.873 ms 1.074 ms 1.162 ms 2 core-from-cmp.uea.ac.uk (10.0.0.1) 0.312 ms 0.350 ms 0.463 ms 3 ueaha1btm-from-uea1 (172.16.0.34) 0.791 ms 0.772 ms 1.238 ms 4 bound-from-ueahatop.uea.ac.uk (193.62.92.71) 5.094 ms 4.451 ms 4.441 ms 5 gi0-3.norw-rbr1.eastnet.ja.net (193.60.0.21) 4.426 ms 5.014 ms 4.389 ms 6 gi3-0-2.chel-rbr1.eastnet.ja.net (193.63.107.114) 6.055 ms 6.039 ms * 7 lond-sbr1.ja.net (146.97.40.45) 6.994 ms 7.493 ms 7.457 ms 8 so-6-0-0.lond-sbr4.ja.net (146.97.33.154) 8.206 ms 8.187 ms 8.234 ms 9 po1.lond-ban4.ja.net (146.97.35.110) 8.673 ms 6.294 ms 7.668 ms 10 bbc.lond-sbr4.ja.net (193.62.157.178) 6.303 ms 8.118 ms 8.107 ms 11 212.58.238.153 (212.58.238.153) 6.245 ms 8.066 ms 6.541 ms 12 212.58.239.62 (212.58.239.62) 7.023 ms 8.419 ms 7.068 ms what i need to do is compare this trace against another one just like it and look for the changes and time differences etc, then print a stats page.

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Culture Sensitive GetHashCode

- by user114928

Hi, I'm writing a c# application that will process some text and provide basic query functions. In order to ensure the best possible support for other languages, I am allowing the users of the application to specify the System.Globalization.CultureInfo (via the "en-GB" style code) and also the full range of collation options using the System.Globalization.CompareOptions flags enum. For regular string comparison I'm then using a combination of: a) String.Compare overload that accepts the culture and options b) For some bulk processes I'm caching the byte data (KeyData) from CompareInfo.GetSortKey (overload that accepts the options) and using a byte-by-byte comparison of the KeyData. This seemed fine (although please comment if you think these two methods shouldn't be mixed), but then I had reason to use the HashSet< class which only has an overload for IEqualityComparer<. MS documentation seems to suggest that I should use StringComparer (which implements both IEqualityComparer< and IComparer<), but this only seems to support the "IgnoreCase" option from CompareOptions and not "IgnoreKanaType", "IgnoreSymbols", "IgnoreWidth" etc. I'm assuming that a StringComparer that ignores these other options could produce different hashcodes for two strings that might be considered the same using my other comparison options. I'd therefore get incorrect results from my application. Only thought at the moment is to create my own IEqualityComparer< that generates a hashcode from the SortKey.KeyData and compares eqality be using the String.Compare overload. Any suggestions?

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Hibernate: Check if object exists/changed

- by swalkner

Assuming I have an object Person with long id String firstName String lastName String address Then I'm generating a Person-object somewhere in my application. Now I'd like to check if the person exists in the database (= firstname/lastname-combination is in the database). If not = insert it. If yes, check, if the address is the same. If not = update the address. Of course, I can do some requests (first, try to load object with firstname/lastname), then (if existing), compare the address. But isn't there a simpler, cleaner approach? If got several different classes and do not like to have so many queries. I'd like to use annotations as if to say: firstname/lastname = they're the primary key. Check for them if the object exists. address is the parameter you have to compare if it stayed the same or not. Does Hibernate/JPA (or another framework) support something like that? pseude-code: if (database.containsObject(person)) { //containing according to compound keys if (database.containsChangedObject(person)) { database.updateObject(person); } } else { database.insertObject(person); }

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heterogeneous comparisons in python3

- by Matt Anderson

I'm 99+% still using python 2.x, but I'm trying to think ahead to the day when I switch. So, I know that using comparison operators (less/greater than, or equal to) on heterogeneous types that don't have a natural ordering is no longer supported in python3.x -- instead of some consistent (but arbitrary) result we raise TypeError instead. I see the logic in that, and even mostly think its a good thing. Consistency and refusing to guess is a virtue. But what if you essentially want the python2.x behavior? What's the best way to go about getting it? For fun (more or less) I was recently implementing a Skip List, a data structure that keeps its elements sorted. I wanted to use heterogeneous types as keys in the data structure, and I've got to compare keys to one another as I walk the data structure. The python2.x way of comparing makes this really convenient -- you get an understandable ordering amongst elements that have a natural ordering, and some ordering amongst those that don't. Consistently using a sort/comparison key like (type(obj).__name__, obj) has the disadvantage of not interleaving the objects that do have a natural ordering; you get all your floats clustered together before your ints, and your str-derived class separates from your strs. I came up with the following: import operator def hetero_sort_key(obj): cls = type(obj) return (cls.__name__+'_'+cls.__module__, obj) def make_hetero_comparitor(fn): def comparator(a, b): try: return fn(a, b) except TypeError: return fn(hetero_sort_key(a), hetero_sort_key(b)) return comparator hetero_lt = make_hetero_comparitor(operator.lt) hetero_gt = make_hetero_comparitor(operator.gt) hetero_le = make_hetero_comparitor(operator.le) hetero_ge = make_hetero_comparitor(operator.gt) Is there a better way? I suspect one could construct a corner case that this would screw up -- a situation where you can compare type A to B and type A to C, but where B and C raise TypeError when compared, and you can end up with something illogical like a > b, a < c, and yet b > c (because of how their class names sorted). I don't know how likely it is that you'd run into this in practice.

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C# 4.0 'dynamic' doesn't set ref/out arguments

- by Buu Nguyen

I'm experimenting with DynamicObject. One of the things I try to do is setting the values of ref/out arguments, as shown in the code below. However, I am not able to have the values of i and j in Main() set properly (even though they are set correctly in TryInvokeMember()). Does anyone know how to call a DynamicObject object with ref/out arguments and be able to retrieve the values set inside the method? class Program { static void Main(string[] args) { dynamic proxy = new Proxy(new Target()); int i = 10; int j = 20; proxy.Wrap(ref i, ref j); Console.WriteLine(i + ":" + j); // Print "10:20" while expect "20:10" } } class Proxy : DynamicObject { private readonly Target target; public Proxy(Target target) { this.target = target; } public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { int i = (int) args[0]; int j = (int) args[1]; target.Swap(ref i, ref j); args[0] = i; args[1] = j; result = null; return true; } } class Target { public void Swap(ref int i, ref int j) { int tmp = i; i = j; j = tmp; } }

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e4x statement conflicts with local variable?

- by semen

Hi, griends! Somewhere in code i have decalred variable: [Bindable] var nameWin:String = ""; after this i have an e4x statement podContent.xml_m = xml_m.item.(nameWin=="necessary name"); that should compare item's namewin with "necessary name" and return only items whose nameWin matches with "necessary name". xml_m.item: <item> <nameWin>necessary name</nameWin> <nameCol>??????-?????? ???????????</nameCol> <date>2009 ???</date> <summa>259267.7976</summa> </item> <item> <nameWin>unnecessary name</nameWin> <nameCol>??????-?????? ???????????</nameCol> <date>2010 ??????</date> <summa>104.3254</summa> </item> <item> <nameWin>necessary name</nameWin> <nameCol>??????-?????? ???????????</nameCol> <date>2010 ???</date> <summa>21.5174</summa> </item> if I use in statement xml-child distinct of nameWin (summa, e. g.), it works good. But with nameWin, e4x compares local variable nameWin (which not interested for me at all at this time) with "necessary name" instead of compare item's nameWin with "necessary name". Any ideas? Versions of libraries can be reason?

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How to Post Javascript to a MySQL Database

- by salientanimal

Hi guys, I have created a form in HTLM and I m trying to post the information in the form to a MySQL database. My form make suse of a dynamic list selection that needs to be captured to the database. However when submtting the form I get the following error Error: Unknown column 'coulmn_name' in 'field list'. Here is my HTML CODE for the form <td height="94"><p align="justify">CALL TRACKER - ADMIN</p></td> Customer Name : E-Mail Address : </tr> <tr> <td width="29%" align="right" valign="middle"><strong>Case Number :</strong></td> <td> <input type="text" name="case_number" width="70%" align="left" valign="middle"> </td> </tr> <tr> <td width="29%" align="right" valign="middle"><strong>MSISDN :</strong></td> <td> <input type="text" name="msisdn" width="70%" align="left" valign="middle"> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Route Cause :</strong></td> <td width="71%" align="left" valign="middle"> <select name="route_cause" id="category" onChange="javascript: listboxchange1(this.options[this.selectedIndex].value);">  <option value="">Select the Call Reason</option> <option value="Billing Admin">Billing Admin</option> <option value="Customer Care">Customer Care</option> <option value="Insurance">Insurance</option> <option value="Repairs">Repairs</option> <option value="SIM Swap">SIM Swap</option> <option value="UTI">UTI</option> </select> </td> </tr> <tr> <td align="right" valign="middle"> <strong>Call Type/Indexed To :</strong></td> <td align="left" valign="middle"> <script type="text/javascript" language="javascript" name="calltype_indexedto">  </script> </td> </tr> <tr> <td align="right" valign="middle"> <strong>Type/TAT :</strong></td> <td align="left" valign="middle"> <script type="text/javascript" language="javascript" name="type_tat">  </script> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Escalated To :</strong></td> <td width="71%" align="left" valign="middle"> <select name="escalatedto" id="escalated_to"> <option value="">Select the Escalation</option> <option value="Billing Ops">Billing Ops</option> <option value="Resolvers">Resolvers</option> <option value="Finance">Finance</option> <option value="Ressolver">Ressolver</option> <option value="Nudebt">Nudebt</option> <option value="Transunion">Transunion</option> <option value="N/A">N/A</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Requested By :</strong></td> <td width="71%" align="left" valign="middle"> <select name="requestedby" id="requested_by"> <option value="">UTI Requested By</option> <option value="Billing">Billing</option> <option value="Customer Service">Customer Service</option> <option value="Insurance">Insurance</option> <option value="Management">Management</option> <option value="Repairs">Repairs</option> <option value="Retail Support">Retail Support</option> <option value="Retentions">Retentions</option> <option value="SIM Swap">SIM Swap</option> <option value="WOW">WOW</option> <option value="N/A">N/A</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"> <strong>Province :</strong></td> <td width="71%" align="left" valign="middle"> <select name="province" id="province"> <option value="">Select the Province</option> <option value="Eastern Cape">Eastern Cape</option> <option value="Gauteng">Gauteng</option> <option value="Kwa-Zulu Natal">Kwa-Zulu Natal</option> <option value="Limpopo">Limpopo</option> <option value="Mpumalanga">Mpumalanga</option> <option value="North West">North West</option> <option value="Northern Cape">Northern Cape</option> <option value="Polokwane">Polokwane</option> <option value="Western Cape">Western Cape</option> <option value="Other">Other</option> </select> </td> </tr> <tr> <td width="29%" align="right" valign="middle"><strong>Comments :</strong></td> <td> <textarea rows ="5" cols="30" name="comments"> </textarea> </td> </tr> <tr> <td> <p> <input type="reset" value="Reset Form"><input type="Submit" value="Submit"> Here is my PHP CODE to write to the Database <?php $con = mysql_connect("hostname" ,"mysqusername" ,"mysqlpassword"); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("databasename", $con); $sql="INSERT INTO customer_services_tracker (customer_name ,customer_email_address ,case_number ,msisdn ,route_cause ,calltype_indexedto ,type_tat ,escalatedto ,requestedby ,province ,comments ) VALUES ('$_POST[customer_name]' ,'$_POST[customer_email_address]' ,'$_POST[case_number]' ,'$_POST[msisdn]' ,'$_POST[route_cause]' ,'$_POST[calltype_indexedto]' ,'$_POST[type_tat]' ,'$_POST[escalatedto]' ,'$_POST[requestedby]' ,'$_POST[province]' ,'$_POST[comments]')"; $CatName = $rowCat["Name"]; if (!mysql_query($sql,$con)) { die('Error: ' . mysql_error()); } echo "1 record added"; mysql_close($con) ?>

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Can I clone an IQueryable in linq? For UNION purposes?

- by user169867

I have a table of WorkOrders. The table has a PrimaryWorker & PrimaryPay field. It also has a SecondaryWorker & SecondaryPay field (which can be null). I wish to run 2 very similar queries & union them so that it will return a Worker Field & Pay field. So if a single WorkOrder record had both the PrimaryWorker and SecondaryWorker field populated I would get 2 records back. The "where clause" part of these 2 queries is very similar and long to construct. Here's a dummy example var q = ctx.WorkOrder.Where(w => w.WorkDate >= StartDt && w.WorkDate <= EndDt); if(showApprovedOnly) { q = q.Where(w => w.IsApproved); } //...more filters applied Now I also have a search flag called "hideZeroPay". If that's true I don't want to include the record if the worker was payed $0. But obviously for 1 query I need to compare the PrimaryPay field and in the other I need to compare the SecondaryPay field. So I'm wondering how to do this. Can I clone my base query "q" and make a primary & secondary worker query out of it and then union those 2 queries together? I'd greatly appreciate an example of how to correctly handle this. Thanks very much for any help.

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Multiple WPFPreviewHandlers in One Window? Can it be done?

- by Scott

Here is the scenario. I am building a part of my desktop app up and I have a need to create a preview handler. I found plenty of examples on the web of a WPF Preview handler, but I wanted to go one step more than just that. Lets say we have multiple documents and I wished to compare them. So the ideal scenario would be able to see documents side by side in a collection. Sort of how BING does their image search. But the more documents I select in a list box, the more documents I can compare all at once. The second Ideal solution would be a tabbed interface. One tab for each document. Sort of like how internet browsers are doing it now. Understand? So here is the question that I have been struggling with. I can get one preview to work in a window, but can’t get the second one to show up. This is all WPF code so maybe im doing something wrong, but can you preview more than one document in a window at a time? My thought is no, because the previewhandler needs a window handler to lock onto. I would love small code sample since COM and handlers aren’t my sort of thing, but I can manage if you are just able to point me down the right track. Here is the code I found for the WPF Handler. http://blogs.microsoft.co.il/blogs/tamir/archive/2008/04/18/using-vista-preview-handlers-in-wpf-application.aspx

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Is there unreachable code in this snippet? I don't think so, but Resharper is telling me otherwise.

- by The Matt

I have the following method I came across in a code review. Inside the loop Resharper is telling me that if (narrativefound == false) is incorrect becuase narrativeFound is always true. I don't think this is the case, because in order to set narrativeFound to true it has to pass the conditional string compare first, so how can it always be true? Am I missing something? Is this a bug in Resharper or in our code? public Chassis GetChassisForElcomp(SPPA.Domain.ChassisData.Chassis asMaintained, SPPA.Domain.ChassisData.Chassis newChassis) { Chassis c = asMaintained; List<Narrative> newNarrativeList = new List<Narrative>(); foreach (Narrative newNarrative in newChassis.Narratives) { bool narrativefound = false; foreach (Narrative orig in asMaintained.Narratives) { if (string.Compare(orig.PCode, newNarrative.PCode) ==0 ) { narrativefound = true; if (newNarrative.NarrativeValue.Trim().Length != 0) { orig.NarrativeValue = newNarrative.NarrativeValue; newNarrativeList.Add(orig); } break; } if (narrativefound == false) { newNarrativeList.Add(newNarrative); } } } c.SalesCodes = newChassis.SalesCodes; c.Narratives = newNarrativeList; return c; }

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Hashing the state of a complex object in .NET

- by Jan

Some background information: I am working on a C#/WPF application, which basically is about creating, editing, saving and loading some data model. The data model contains of a hierarchy of various objects. There is a "root" object of class A, which has a list of objects of class B, which each has a list of objects of class C, etc. Around 30 classes involved in total. Now my problem is that I want to prompt the user with the usual "you have unsaved changes, save?" dialog, if he tries to exit the program. But how do I know if the data in current loaded model is actually changed? There is of course ways to solve this, like e.g. reloading the model from file and compare against the one in memory value by value or make every UI control set a flag indicating the model has been changed. Now instead, I want to create a hash value based on the model state on load and generate a new value when the user tries to exit, and compare those two. Now the question: So inspired of that, I was wondering if there exist some way to generate a hash value from the (value)state of some arbitrary complex object? Preferably in a generic way, e.g. no need to apply attributes to each involved class/field. One idea could be to use some of .NET's serialization functionality (assuming it will work out-of-the-box in this case) and apply a hash function to the content of the resulting file. However, I guess there exist some more suitable approach. Thanks in advance.

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Any diff/merge tool that provides a report (metrics) of conflicts?

- by cad

CONTEXT: I am preparing a big C# merge using visual studio 2008 and TFS. I need to create a report with the files and the number of collisions (total changes and conflicts) for each file (and in total of course) PROBLEM: I cannot do it for two reasons (first one is solved): 1- Using TFS merge I can have access to the file comparison but I cannot export the list of conflicting files... I can only try to resolve the conflicts. (I have solved problem 1 using beyond compare. It allows me to export the file list) 2- Using TFS merge I can only access manually for each file to get the number of conflicts... but I have more than 800 files (and probably will have to repeat it in the close future so is not an option doing it manually) There are dozens of file comparison tools (http://en.wikipedia.org/wiki/Comparison_of_file_comparison_tools ) but I am not sure which one could (if any) give me these metrics. I have also read several forums and questions here but are more general questions (which diff tool is better) and I am looking for a very specific report. So my questions are: Is Visual Studio 2010 (using still TFS2008) capable of doing such reports/exportation? Is there any tool that provide this kind of metrics (Now I am trying Beyond Compare)

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convert htmlelement to string for comparison javascript

- by Jamex

Hi, I am using a function that obtains a target element id at onclick. Example, if I click on the text element that has the id of 'help'. var click = (e && e.target) || (event && event.srcElement); The var click would contain the ref to the id of "help". I want to compare the var click to the string 'help' using the if statement below. if (click == 'about') {do something} The comparison does not work because the var click is not a string. When I use the alert(click) to debug, it shows click as "object HTMLElement". How would you compare whether the id 'help' is obtained from var click? I could write out something like if (click == document.getElementById('help')) {do something} but that would make a long statement. also if the var click is document.getElementById('help'), how would you make a new var "show" as document.getElementById('showhelp') basically, I want to use the same function to generate dynamic responses to each element that was clicked on, and not having to create a separate function for each element.

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What's the recommended implementation for hashing OLE Variants?

- by Barry Kelly

OLE Variants, as used by older versions of Visual Basic and pervasively in COM Automation, can store lots of different types: basic types like integers and floats, more complicated types like strings and arrays, and all the way up to IDispatch implementations and pointers in the form of ByRef variants. Variants are also weakly typed: they convert the value to another type without warning depending on which operator you apply and what the current types are of the values passed to the operator. For example, comparing two variants, one containing the integer 1 and another containing the string "1", for equality will return True. So assuming that I'm working with variants at the underlying data level (e.g. VARIANT in C++ or TVarData in Delphi - i.e. the big union of different possible values), how should I hash variants consistently so that they obey the right rules? Rules: Variants that hash unequally should compare as unequal, both in sorting and direct equality Variants that compare as equal for both sorting and direct equality should hash as equal It's OK if I have to use different sorting and direct comparison rules in order to make the hashing fit. The way I'm currently working is I'm normalizing the variants to strings (if they fit), and treating them as strings, otherwise I'm working with the variant data as if it was an opaque blob, and hashing and comparing its raw bytes. That has some limitations, of course: numbers 1..10 sort as [1, 10, 2, ... 9] etc. This is mildly annoying, but it is consistent and it is very little work. However, I do wonder if there is an accepted practice for this problem.

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Formating Date in Freemarker to say "Today", "Yesterday", etc.

- by egervari

Is there a way in freemarker to compare dates to test if the date is today or yesterday... or do I have to write code in Java to do these tests? I basically want to do this: <#------------------------------------------------------------------------------ formatDate -------------------------------------------------------------------------------> <#macro formatDate date showTime=true> <#if date??> <span class="Date"> <#if date?is_today> Today <#elseif date?is_yesterday> Yesterday <#else> ${date?date} </#if> </span> <#if showTime> <span class="Time">${date?time}</span> </#if> </#if> </#macro> EDIT: My best guess to implement this is to pass "today" and "yesterday" into the model for the pages that use this function and then compare the date values against these 2 objects in the model. I am out of out of options, but I'd rather not have to do this for every page that uses this macro. Any other options that are nicer? <#if date??> <span class="Date"> <#if date?date?string.short == today?date?string.short> Today <#elseif date?date?string.short == yesterday?date?string.short> Yesterday <#else> ${date?date} </#if> </span> <#if showTime> <span class="Time">${date?time}</span> </#if> </#if>

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Validating Login / Changing User settings / Php Mysql

- by Marcelo

Hi everyone, my questions are about login, and changing already saved data. (Q1) 'Till now I've only saved input in the tables of the database (registration steps), now I need to check if the input (login steps), are the same of my table in database, in fact I have 3 types of users, then I'll have to check 3 kind of tables. Then if the input data matches with one of those 3 tables I will redirect the user to his specific area. I'm thinking about saved the submitted data $login=$_REQUEST['login']; and $password=$_REQUEST['password']; and compare with the login column in the database. Then if the login matches, I'll compare the password submitted with the one in the row, not in the column. But I don't know how to do this search and comparison,neither what to use. Then if both matches I'll redirect the user. Else I'll send an login error message. (this I know how to do) (Q2) What if need to change an already saved user ? For example to change an email address. My changing user's data web page is exactly the same like the registration user web page. Can I load the already saved options and values of registration (table user for example). Then the user will change whatever he thinks it's necessary, and then when he submits the new information, they would not create a new row in my table, but just be overwritten the old information? How can I do this? Sorry for any mistake in English, and Thanks for the attention.

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Improve Log Exceptions

- by Jaider

I am planning to use log4net in a new web project. In my experience, I see how big the log table can get, also I notice that errors or exceptions are repeated. For instance, I just query a log table that have more than 132.000 records, and I using distinct and found that only 2.500 records are unique (~2%), the others (~98%) are just duplicates. so, I came up with this idea to improve logging. Having a couple of new columns: counter and updated_dt, that are updated every time try to insert same record. If want to track the user that cause the exception, need to create a user_log or log_user table, to map N-N relationship. Create this model may made the system slow and inefficient trying to compare all these long text... Here the trick, we should also has a hash column of binary of 16 or 32, that hash the message and the exception, and configure an index on it. We can use HASHBYTES to help us. I am not an expert in DB, but I think that will made the faster way to locate a similar record. And because hashing doesn't guarantee uniqueness, will help to locale those similar record much faster and later compare by message or exception directly to make sure that are unique. This is a theoretical/practical solution, but will it work or bring more complexity? what aspects I am leaving out or what other considerations need to have? the trigger will do the job of insert or update, but is the trigger the best way to do it?

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Using shared_ptr to implement RCU (read-copy-update)?

- by yongsun

I'm very interested in the user-space RCU (read-copy-update), and trying to simulate one via tr1::shared_ptr, here is the code, while I'm really a newbie in concurrent programming, would some experts help me to review? The basic idea is, reader calls get_reading_copy() to gain the pointer of current protected data (let's say it's generation one, or G1). writer calls get_updating_copy() to gain a copy of the G1 (let's say it's G2), and only one writer is allowed to enter the critical section. After the updating is done, writer calls update() to do a swap, and make the m_data_ptr pointing to data G2. The ongoing readers and the writer now hold the shared_ptr of G1, and either a reader or a writer will eventually deallocate the G1 data. Any new readers would get the pointer to G2, and a new writer would get the copy of G2 (let's say G3). It's possible the G1 is not released yet, so multiple generations of data my co-exists. template <typename T> class rcu_protected { public: typedef T type; typedef std::tr1::shared_ptr<type> rcu_pointer; rcu_protected() : m_data_ptr (new type()) {} rcu_pointer get_reading_copy () { spin_until_eq (m_is_swapping, 0); return m_data_ptr; } rcu_pointer get_updating_copy () { spin_until_eq (m_is_swapping, 0); while (!CAS (m_is_writing, 0, 1)) {/* do sleep for back-off when exceeding maximum retry times */} rcu_pointer new_data_ptr(new type(*m_data_ptr)); // as spin_until_eq does not have memory barrier protection, // we need to place a read barrier to protect the loading of // new_data_ptr not to be re-ordered before its construction _ReadBarrier(); return new_data_ptr; } void update (rcu_pointer new_data_ptr) { while (!CAS (m_is_swapping, 0, 1)) {} m_data_ptr.swap (new_data_ptr); // as spin_until_eq does not have memory barrier protection, // we need to place a write barrier to protect the assignments of // m_is_writing/m_is_swapping be re-ordered bofore the swapping _WriteBarrier(); m_is_writing = 0; m_is_swapping = 0; } private: volatile long m_is_writing; volatile long m_is_swapping; rcu_pointer m_data_ptr; };

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How to use Comparator in Java to sort

- by Dan

I learned how to use the comparable but I'm having difficulty with the Comparator. I am having a error in my code: Exception in thread "main" java.lang.ClassCastException: New.People cannot be cast to java.lang.Comparable at java.util.Arrays.mergeSort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.Collections.sort(Unknown Source) at New.TestPeople.main(TestPeople.java:18) Here is my code: import java.util.Comparator; public class People implements Comparator{ private int id; private String info; private double price; public People(int newid, String newinfo, double newprice){ setid(newid); setinfo(newinfo); setprice(newprice); } public int getid() { return id; } public void setid(int id) { this.id = id; } public String getinfo() { return info; } public void setinfo(String info) { this.info = info; } public double getprice() { return price; } public void setprice(double price) { this.price = price; } public int compare(Object obj1, Object obj2) { Integer p1 = ((People)obj1).getid(); Integer p2 = ((People)obj2).getid(); if (p1 p2 ){ return 1; } else if (p1 < p2){ return -1; } else return 0; } } import java.util.ArrayList; import java.util.Collections; public class TestPeople { public static void main(String[] args) { ArrayList peps = new ArrayList(); peps.add(new People(123, "M", 14.25)); peps.add(new People(234, "M", 6.21)); peps.add(new People(362, "F", 9.23)); peps.add(new People(111, "M", 65.99)); peps.add(new People(535, "F", 9.23)); Collections.sort(peps); for(int i=0;i I believe it has to do something with the casting in the compare method but I was playing around with it and still could not find the solution

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mmap only needed pages of kernel buffer to user space

- by axeoth

See also this answer: http://stackoverflow.com/a/10770582/1284631 I need something similar, but without having to allocate a buffer: the buffer is large, in theory, but the user space program only needs to access some parts of it (it mocks some registers of a hardware). As I cannot allocate with vmalloc_user() such a large buffer (kernel 32 bit, in embedded environment, no swap...), I followed the same approach as in the quoted answer, trying to allocate only those pages that are really requested by the user space. So: I use a my_mmap() function for the device file (actually, is the .mmap field of a struct uio_info) to set up the fields of the vma, then, in the vm_area_struct's .fault field (also named my_fault()), I should return a page. except that: In the my_fault() method of vm_area_struct, I cannot obtain a page through: vmf->page=vmalloc_to_page(my_buf + (vmf->pgoff << PAGE_SHIFT)); since there is no allocated buffer: my_buf = vmalloc_user(MY_BUF_SIZE); fails with "allocation failed: out of vmalloc space - use vmalloc= to increase size." (and there is no room or swap to increase that vmalloc= parameter). So, I would need to get a page from the kernel and fill the vmf->page field. How to allocate a page (I assume that the offset of the page is known, as it is vm->pgoff). What base memory should I use instead of my_buf? PS: I also did set up the vma->flags |= VM_NORESERVE; (in the my_mmap()), but not sure if it helps. Is there any vmalloc_user_unreserved()-like function? (let's say, lazy allocation) Also, writing 1 to /proc/sys/vm/overcommit_memory and large values (eg 500) to /proc/sys/vm/overcommit_ratio before trying to my_buf=vmalloc_user(<large_size>) didn't work.

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Project Euler #14 and memoization in Clojure

- by dbyrne

As a neophyte clojurian, it was recommended to me that I go through the Project Euler problems as a way to learn the language. Its definitely a great way to improve your skills and gain confidence. I just finished up my answer to problem #14. It works fine, but to get it running efficiently I had to implement some memoization. I couldn't use the prepackaged memoize function because of the way my code was structured, and I think it was a good experience to roll my own anyways. My question is if there is a good way to encapsulate my cache within the function itself, or if I have to define an external cache like I have done. Also, any tips to make my code more idiomatic would be appreciated. (use 'clojure.test) (def mem (atom {})) (with-test (defn chain-length ([x] (chain-length x x 0)) ([start-val x c] (if-let [e (last(find @mem x))] (let [ret (+ c e)] (swap! mem assoc start-val ret) ret) (if (<= x 1) (let [ret (+ c 1)] (swap! mem assoc start-val ret) ret) (if (even? x) (recur start-val (/ x 2) (+ c 1)) (recur start-val (+ 1 (* x 3)) (+ c 1))))))) (is (= 10 (chain-length 13)))) (with-test (defn longest-chain ([] (longest-chain 2 0 0)) ([c max start-num] (if (>= c 1000000) start-num (let [l (chain-length c)] (if (> l max) (recur (+ 1 c) l c) (recur (+ 1 c) max start-num)))))) (is (= 837799 (longest-chain))))

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IComparer for integers with and empty strings at end

- by paulio

Hi, I've written the following IComparer but I need some help. I'm trying to sort a list of numbers but some of the numbers may not have been filled in. I want these numbers to be sent to the end of the list at all times.. for example... [EMPTY], 1, [EMPTY], 3, 2 would become... 1, 2, 3, [EMPTY], [EMPTY] and reversed this would become... 3, 2, 1, [EMPTY], [EMPTY] Any ideas? public int Compare(ListViewItem x, ListViewItem y) { int comparison = int.MinValue; ListViewItem.ListViewSubItem itemOne = x.SubItems[subItemIndex]; ListViewItem.ListViewSubItem itemTwo = y.SubItems[subItemIndex]; if (!string.IsNullOrEmpty(itemOne.Text) && !string.IsNullOrEmpty(itemTwo.Text)) { uint itemOneComparison = uint.Parse(itemOne.Text); uint itemTwoComparison = uint.Parse(itemTwo.Text); comparison = itemOneComparison.CompareTo(itemTwoComparison); } else { // ALWAYS SEND TO BOTTOM/END OF LIST. } // Calculate correct return value based on object comparison. if (OrderOfSort == SortOrder.Descending) { // Descending sort is selected, return negative result of compare operation. comparison = (-comparison); } else if (OrderOfSort == SortOrder.None) { // Return '0' to indicate they are equal. comparison = 0; } return comparison; } Cheers.

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