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  • Does a rollback still occur if I use begin...rescue and an error occurs?

    - by codeman73
    I've got some strange errors happening in my rails app and I'm trying to log better errors instead of the whole stack of passenger stuff that I don't care about. I thought I would do this with a Rescue clause and explicit error handling, like logging the params hash. But I'm concerned if this would interrupt any rollback that is happening. For that matter, I'm assuming rollbacks automatically occur when an error occurs as part of the normal rails error handling, but I haven't been able to find that documented anywhere. I'm using Dreamhost with MySQL, so I thought transactions and rollbacks were happening there.

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  • changing window.location without triggering refresh

    - by jdwyah
    I have an AJAX form that submits GET requests. Because these are all GET requests these should be easily bookmark-able. Preferably I'd make my Ajax request, update the screen and then update window.location.href to be the URL for the new page. Unfortunately this reloads the page. Is there any way I can get around this? Basically I'd like the URL bar to be a permalink bar, but it needs to be able to change to keep up with the state of the page. window.location.hash is no good because that doesn't get sent to the server.

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  • How to validate Windows VC++ DLL on Unix systems

    - by Guildencrantz
    I have a solution, mostly C#, but with a few VC++ projects, that is pushed through our standard release process (perl and bash scripts on Unix boxes). Currently the initiative is to validate DLL and EXE versions as they pass through the process. All the versioning is set so that File Version is of the format $Id: $ (between the colon and the second dollar should be a git commit hash), and the Product Version is of the format $Hudson Build: $ (between the colon and the second dollar should be a string representing the hudson build details). Currently this system works extremely well for the C# projects because this version information is stored as plain strings within the compiled code (you can literally use the unix strings command and see the version information); the problem is that the VC++ projects do not expose this information as strings (I have used a windows system to verify that the version information is correctly being set), so I'm not sure how to extract the version on a unix system. Any suggestions for either A) Getting a string representation of the version embedded in the compiled code, or B) A utility/script which can extract this information?

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  • Fastest/One-liner way to list attr_accessors in Ruby?

    - by viatropos
    What's the shortest, one-liner way to list all methods defined with attr_accessor? I would like to make it so, if I have a class MyBaseClass, anything that extends that, I can get the attr_accessor's defined in the subclasses. Something like this: class MyBaseClass < Hash def attributes # ?? end end class SubClass < MyBaseClass attr_accessor :id, :title, :body end puts SubClass.new.attributes.inspect #=> [id, title, body] What about to display just the attr_reader and attr_writer definitions?

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  • htaccess redirect conditions

    - by user271619
    I figured out how to redirect someone, if they happen across one particular filename: Redirect /index.php http://www.website.com/#myaccount As you can see, I'm pretty much redirecting that visitor to the same page, which doesn't work. It's an endless look, regardless of the slight/minuscule change. I want to force someone to see a part of the page, by adding the hash. (it's a little weird, I know) I'm guessing this may be a time to use regex in the htaccess file. But I thought I'd ask if there's a simpler way to do this from the htaccess file.

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  • Secure password transmission over unencrypted tcp/ip

    - by academicRobot
    I'm in the designing stages of a custom tcp/ip protocol for mobile client-server communication. When not required (data is not sensitive), I'd like to avoid using SSL for overhead reasons (both in handshake latency and conserving cycles). My question is, what is the best practices way of transmitting authentication information over an unencrypted connection? Currently, I'm liking SRP or J-PAKE (they generate secure session tokens, are hash/salt friendly, and allow kicking into TLS when necessary), which I believe are both implemented in OpenSSL. However, I am a bit wary since I don't see many people using these algorithms for this purpose. Would also appreciate pointers to any materials discussing this topic in general, since I had trouble finding any.

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  • What's a good algorithm for searching arrays N and M, in order to find elements in N that also exist

    - by GenTiradentes
    I have two arrays, N and M. they are both arbitrarily sized, though N is usually smaller than M. I want to find out what elements in N also exist in M, in the fastest way possible. To give you an example of one possible instance of the program, N is an array 12 units in size, and M is an array 1,000 units in size. I want to find which elements in N also exist in M. (There may not be any matches.) The more parallel the solution, the better. I used to use a hash map for this, but it's not quite as efficient as I'd like it to be. Typing this out, I just thought of running a binary search of M on sizeof(N) independent threads. (Using CUDA) I'll see how this works, though other suggestions are welcome.

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  • Serial numbers generation without user data

    - by Sphynx
    This is a followup to this question. The accepted answer is generally sufficient, but requires user to supply personal information (e.g. name) for generating the key. I'm wondering if it's possible to generate different keys based on a common seed, in a way that program would be able to validate if those keys belong to particular product, but without making this process obvious to the end user. I mean it could be a hash of product ID plus some random sequence of characters, but that would allow user to guess potential new keys. There should be some sort of algorithm difficult to guess.

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  • Amazon EC2 multiple servers share session state

    - by Theofanis Pantelides
    Hi everyone, I have a bunch of EC2 servers that are load balanced. Some of the servers are not sharing session, and users keep getting logged in and out. How can I make all the server share the one session, possibly even using a partitionresolver solution public class PartitionResolver : System.Web.IPartitionResolver { private String[] partitions; public void Initialize() { // create the partition connection string table // web1, web2 partitions = new String[] { "192.168.1.1" }; } public String ResolvePartition(Object key) { String oHost = System.Web.HttpContext.Current.Request.Url.Host.ToLower().Trim(); if (oHost.StartsWith("10.0.0") || oHost.Equals("localhost")) return "tcpip=127.0.0.1:42424"; String sid = (String)key; // hash the incoming session ID into // one of the available partitions Int32 partitionID = Math.Abs(sid.GetHashCode()) % partitions.Length; return ("tcpip=" + partitions[partitionID] + ":42424"); } } -theo

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  • Get current session /process id from inside a mysql query

    - by Indra Ginanjar
    I'm trying to create a table for pseudo array variable. That looks like CREATE TABLE IF NOT EXISTS `MyArray`.`ArrayTable` ( `ID` INT UNSIGNED NOT NULL COMMENT 'Hash value of SessionID + ArrayName' , `SessionID` INT UNSIGNED NOT NULL , `ArrayName` CHAR(26) NOT NULL COMMENT '32 digit char - 6 digit longest process id (assumtion)' , `Index` INT UNSIGNED NOT NULL , `Value` TEXT NOT NULL , PRIMARY KEY (`ID`, `SessionID`) ) ENGINE = MyISAM; The table is not normalized yet, 'hope this will make it a little simpler to understand :) To avoid collission between client, there should be a differentiator between client session. For that reason i think need to know current session/process id (just like "SHOW PROCESSLIST") but really need to know IN WHICH process the query are?

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  • Plotting Tweets from DB in Ruby, grouping by hour.

    - by plotti
    Hey guys I've got a couple of issues with my code. I was wondering that I am plotting the results very ineffectively, since the grouping by hour takes ages the DB is very simple it contains the tweets, created date and username. It is fed by the twitter gardenhose. Thanks for your help ! require 'rubygems' require 'sequel' require 'gnuplot' DB = Sequel.sqlite("volcano.sqlite") tweets = DB[:tweets] def get_values(keyword,tweets) my_tweets = tweets.filter(:text.like("%#{keyword}%")) r = Hash.new start = my_tweets.first[:created_at] my_tweets.each do |t| hour = ((t[:created_at]-start)/3600).round r[hour] == nil ? r[hour] = 1 : r[hour] += 1 end x = [] y = [] r.sort.each do |e| x << e[0] y << e[1] end [x,y] end keywords = ["iceland", "island", "vulkan", "volcano"] values = {} keywords.each do |k| values[k] = get_values(k,tweets) end Gnuplot.open do |gp| Gnuplot::Plot.new(gp) do |plot| plot.terminal "png" plot.output "volcano.png" plot.data = [] values.each do |k,v| plot.data << Gnuplot::DataSet.new([v[0],v[1]]){ |ds| ds.with = "linespoints" ds.title = k } end end end

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  • REST authentication S3 like hmac sha1 signature vs symetric data encryption.

    - by coulix
    Hello stackers, I was arguing about an S3 like aproach using authorization hash with a secret key as the seed and some data on the request as the message signed with hmac sha1 (Amazon S3 way) vs an other developer supporting symetric encryption of the data with a secret key known by the emiter and the server. What are the advantage of using signed data with hmac sha1 vs symetric key other than the fact that with the former, we do not need to encrypt the username or password. What would be the hardest to break ? symetric encryption or sha1 hashing at la S3 ? If all big players are using oauth and similar without symetric key it is sure that there are obvious advantages, what are those ?

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  • Rails is not passing the "commit" button parameter

    - by Wayne M
    Reinstalling a Rails app on a new server. Part of the app can fork in one of two directions based on the button the user selects. This part isn't working, and when I look at the log I see the values that I gave the form, execept for the commit portion of the params hash. This seems to be why the app isn't working as expected (since there's nothing in params[:commit], but I have no idea why commit would not be passed in; the request is definitely a POST request, and all of the other parameters are there.

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  • Obtain patterns in one file from another using ack or awk or better way than grep?

    - by Rock
    Is there a way to obtain patterns in one file (a list of patterns) from another file using ack as the -f option in grep? I see there is an -f option in ack but it's different with the -f in grep. Perhaps an example will give you a better idea. Suppose I have file1: file1: a c e And file2: file2: a 1 b 2 c 3 d 4 e 5 And I want to obtain all the patterns in file1 from file2 to give: a 1 c 3 e 5 Can ack do this? Otherwise, is there a better way to handle the job (such like awk or using hash) because I have millions of records in both files and really need an efficient way to complete? Thanks!

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  • Java: how to represent graphs?

    - by Rosarch
    I'm implementing some algorithms to teach myself about graphs and how to work with them. What would you recommend is the best way to do that in Java? I was thinking something like this: public class Vertex { private ArrayList<Vertex> outnodes; //Adjacency list. if I wanted to support edge weight, this would be a hash map. //methods to manipulate outnodes } public class Graph { private ArrayList<Vertex> nodes; //algorithms on graphs } But I basically just made this up. Is there a better way? Also, I want it to be able to support variations on vanilla graphs like digraphs, weighted edges, multigraphs, etc.

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  • Flask Admin didn't show all fields

    - by twoface88
    I have model like this: class User(db.Model): __tablename__ = 'users' __table_args__ = {'mysql_engine' : 'InnoDB', 'mysql_charset' : 'utf8'} id = db.Column(db.Integer, primary_key=True) username = db.Column(db.String(80), unique=True) email = db.Column(db.String(120), unique=True) _password = db.Column('password', db.String(80)) def __init__(self, username = None, email = None, password = None): self.username = username self.email = email self._set_password(password) def _set_password(self, password): self._password = generate_password_hash(password) def _get_password(self): return self._password def check_password(self, password): return check_password_hash(self._password, password) password = db.synonym("_password", descriptor=property(_get_password, _set_password)) def __repr__(self): return '<User %r>' % self.username I have ModelView: class UserAdmin(sqlamodel.ModelView): searchable_columns = ('username', 'email') excluded_list_columns = ['password'] list_columns = ('username', 'email') form_columns = ('username', 'email', 'password') But no matter what i do, flask admin didn't show password field when i'm editing user info. Is there any way ? Even just to edit hash code. UPDATE: https://github.com/mrjoes/flask-admin/issues/78

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  • Twisted Spread: How to authenticate each RPC with digital signature

    - by kronat
    I have remote objects which talk each others with RPCs, using Twisted Spread. I want that objects authenticate messages, before using them, with digital signatures, but I don't know where to start to implement this. In my head, the Root object must have a public/private key pair, and the Client too. When a message is sent, a digital signature of the hash is added, and when it is received, the signature is checked. Is the Protocol part where I need to add these adds and checks? Thank you

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  • How do I choose a database?

    - by liamzebedee
    I need a comparison table of some sort for database varieties (MySQL, SQLite etc.). I can't find one. My use case is, I am implementing storage of objects in a distributed hash table. I need a database solution that is: Fast for sorting Simplistic (no users, preferably no additional structures like multiple tables etc.) Concurrent (if possible) Multi-platform File based (not stored in memory primarily) Centralized I will be programming in Go. As I understand, I believe I need what is called a Document Orientated Database, because I am storing objects, identified by keys. EDIT: While I am implementing a DHT, I will also be storing metadata about the objects, such as access counts etc. It would also be preferable to have TLL (time to live)

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  • Best Practice for CouchDB Document Versioning

    - by Groundwater
    Following my question here I am exmploring ideas for a generic approach to document versioning in CouchDB. While I imagine there may be no canonical approach, I had the following idea and am looking for feedback. I would like to maintain readable document ids as much as possible, so a document existing at /document1 would contain a pointer document to all existing versions on the system. The actual revision documents would be at something like /document1/308ef032a3801a where 308ef032a3801a is some random number or hash. Example The pointer document { "_id" : "document1", "versions" : [ "document1/308ef032a3801a" ] } The version document { "_id" : "document1/308ef032a3801a", ... actual content }

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  • MVC Forms Authentication with custom database

    - by AndrewVos
    I'm trying to get forms authentication working for an mvc site. I have a custom database with a users table, and I would like to do my own password validation. I am logging in my user like this: if (PasswordHasher.Hash(password) == dataUser.Password) { FormsAuthentication.SetAuthCookie(email, true); return true; } The problem is, when the session expires obviously the user has to login again. I am thinking I should be storing this Auth cookie in my users table? Update: I'm obviously in desperate need of more education in this area. I just noticed that the user stays authenticated even after an iisreset. I guess what I'm asking is how can I get persistent and non persistent authentication working properly. I want a user to not have to login again if they click "remember", and if they don't then their authentication should expire when the forms authentication is set to expire.

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  • Should I learn Haskell or F# if I already know OCaml?

    - by Unknown
    I am wondering if I should continue to learn OCaml or switch to F# or Haskell. Here are the criteria I am most interested in: Longevity Which language will last longer? I don't want to learn something that might be abandoned in a couple years by users and developers. Will Inria, Microsoft, University of Glasgow continue to support their respective compilers for the long run? Practicality Articles like this make me afraid to use Haskell. A hash table is the best structure for fast retrieval. Haskell proponents in there suggest using Data.Map which is a binary tree. I don't like being tied to a bulky .NET framework unless the benefits are large. I want to be able to develop more than just parsers and math programs. Well Designed I like my languages to be consistent. Please support your opinion with logical arguments and citations from articles. Thank you.

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  • What's the fastest way to compare two objects in PHP?

    - by johnnietheblack
    Let's say I have an object - a User object in this case - and I'd like to be able to track changes to with a separate class. The User object should not have to change it's behavior in any way for this to happen. Therefore, my separate class creates a "clean" copy of it, stores it somewhere locally, and then later can compare the User object to the original version to see if anything changed during its lifespan. Is there a function, a pattern, or anything that can quickly compare the two versions of the User object? Option 1 Maybe I could serialize each version, and directly compare, or hash them and compare? Option 2 Maybe I should simply create a ReflectionClass, run through each of the properties of the class and see if the two versions have the same property values? Option 3 Maybe there is a simple native function like objects_are_equal($object1,$object2);? What's the fastest way to do this?

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  • I want absolute atomicity on a single couchdb instance (insert, fail if already existing)

    - by MatternPatching
    I've come to really love the couchdb style of organizing and updating data, but there are a few situations where I really need to be able to create an entry and determine if an equivalent entry is already in existence before returning to the user. The only situation that this is absolutely necessary for my application is user registration. I'm fine with having all user registration writes go to a particular, designated couchdb instance known as the "registration-instance". I want to hash the user_id into some _id to use. Then execute a put with this _id, but fail if the _id is already inserted. I need to return to the user that the user name is already reserved, and I cannot detect the conflict later and resolve it at that point, because the user would be under the impression that they had reserved the user name. I don't see why couchdb couldn't provide some way to do this, under the assumption that you designate that inserts for a particular "type" of document always are routed to a particular instance.

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  • Dynamic Custom Fields for Data Model

    - by Jerry Deng
    I am in the process of creating a dynamic database where user will be able to create resource type where he/she can add custom fields (multiple texts, strings, and files) Each resource type will have the ability to display, import, export its data; I've been thinking about it and here are my approaches. I would love to hear what do you guys think. Ideas: just hashing all the custom data in a data field (pro: writing is easier, con: reading back out may be harder); children fields (the model will have multiple fields of strings, fields of text, and fields for file path); fixed number of custom fields in the same table with a key mapping data hash stored in the same row; Non-SQL approach, but then the problem would be generating/changing models on the fly to work with different custom fields;

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  • What is a simple C library for a set of integer sets?

    - by conradlee
    I've got to modify a C program and I need to include a set of unsigned integer sets. That is, I have millions of sets of integers (each of these integer sets contains between 3 and 100 integers), and I need to store these in some structure, lets call it the directory, that can in logarithmic time tell me whether a given integer set already exists in the directory. The only operations that need to be defined on the directory is lookup and insert. This would be easy in languages with built-in support for useful data structures, but I'm a foreigner to C and looking around on Google did (surprisingly) not answer my question satisfactorily. This project looks about right: http://uthash.sourceforge.net/ but I would need to come up with my own hash key generator. This is a standard, simple problem, so I hope there is a standard and simple solution.

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