Search Results

Search found 23265 results on 931 pages for 'justin case'.

Page 855/931 | < Previous Page | 851 852 853 854 855 856 857 858 859 860 861 862  | Next Page >

  • realtime diagnostics

    - by Ion Todirel
    I have an application which has a loop, part of a "Scheduler", which runs at all time and is the heart of the application. Pretty much like a game loop, just that my application is a WPF application and it's not a game. Naturally the application does logging at many points, but the Scheduler does some sensitive monitoring, and sometimes it's impossible just from the logs to tell what may have gotten wrong (and by wrong I don't mean exceptions) or the current status. Because Scheduler's inner loop runs at short intervals, you can't do file I/O-based logging (or using the Event Viewer) in there. First, you need to watch it in real-time, and secondly the log file would grow in size very fast. So I was thinking of ways to show this data to the user in the realtime, some things I considered: Display the data in realtime in the UI Use AllocConsole/WriteConsole to display this information in a console Use a different console application which would display this information, communicate between the Scheduler and the console app using pipes or other IPC techniques Use Windows' Performance Monitor and somehow feed it with this information ETW Displaying in the UI would have its issues. First it doesn't integrate with the UI I had in mind for my application, and I don't want to complicate the UI just for this. This diagnostics would only happen rarely. Secondly, there is going to be some non-trivial data protection, as the Scheduler has it's own thread. A separate console window would work probably, but I'm still worried if it's not too much threshold. Allocating my own console, as this is a windows app, would probably be better than a different console application (3), as I don't need to worry about IPC communication, and non-blocking communication. However a user could close the console I allocated, and it would be problematic in that case. With a separate process you don't have to worry about it. Assuming there is an API for Performance Monitor, it wouldn't be integrated too well with my app or apparent to the users. Using ETW also doesn't solve anything, just a random idea, I still need to display this information somehow. What others think, would there be other ways I missed?

    Read the article

  • Putting update logic in your migrations

    - by Daniel Abrahamsson
    A couple of times I've been in the situation where I've wanted to refactor the design of some model and have ended up putting update logic in migrations. However, as far as I've understood, this is not good practice (especially since you are encouraged to use your schema file for deployment, and not your migrations). How do you deal with these kind of problems? To clearify what I mean, say I have a User model. Since I thought there would only be two kinds of users, namely a "normal" user and an administrator, I chose to use a simple boolean field telling whether the user was an adminstrator or not. However, after I while I figured I needed some third kind of user, perhaps a moderator or something similar. In this case I add a UserType model (and the corresponding migration), and a second migration for removing the "admin" flag from the user table. And here comes the problem. In the "add_user_type_to_users" migration I have to map the admin flag value to a user type. Additionally, in order to do this, the user types have to exist, meaning I can not use the seeds file, but rather create the user types in the migration (also considered bad practice). Here comes some fictional code representing the situation: class CreateUserTypes < ActiveRecord::Migration def self.up create_table :user_types do |t| t.string :name, :nil => false, :unique => true end #Create basic types (can not put in seed, because of future migration dependency) UserType.create!(:name => "BASIC") UserType.create!(:name => "MODERATOR") UserType.create!(:name => "ADMINISTRATOR") end def self.down drop_table :user_types end end class AddTypeIdToUsers < ActiveRecord::Migration def self.up add_column :users, :type_id, :integer #Determine type via the admin flag basic = UserType.find_by_name("BASIC") admin = UserType.find_by_name("ADMINISTRATOR") User.all.each {|u| u.update_attribute(:type_id, (u.admin?) ? admin.id : basic.id)} #Remove the admin flag remove_column :users, :admin #Add foreign key execute "alter table users add constraint fk_user_type_id foreign key (type_id) references user_types (id)" end def self.down #Re-add the admin flag add_column :users, :admin, :boolean, :default => false #Reset the admin flag (this is the problematic update code) admin = UserType.find_by_name("ADMINISTRATOR") execute "update users set admin=true where type_id=#{admin.id}" #Remove foreign key constraint execute "alter table users drop foreign key fk_user_type_id" #Drop the type_id column remove_column :users, :type_id end end As you can see there are two problematic parts. First the row creation part in the first model, which is necessary if I would like to run all migrations in a row, then the "update" part in the second migration that maps the "admin" column to the "type_id" column. Any advice?

    Read the article

  • Experienced developer trying to get outsourcing contract with current client.

    - by Mike
    I work for a major bank as a contract software developer. I've been there a few months, and without exception this place has the worst software practices I've ever seen. The software my team makes has no formal testing, terrible code (not reusable, hard to read, etc), minimal documentation, no defined development process and an absolutely sickening amount of waste due to bureaucratic overhead. Part of my contract is to maintain a group of thousands of very poorly written batch jobs. When one of the jobs fails (read: crashes), it's a developers job to look at the source, figure out what's wrong, fix it, and check it in. There is no quality assurance process or auditing of the results whatsoever. Once the developer says "it works" a manager signs off and it goes into production. What's disturbing is that these jobs essentially grab market data and put it into a third-party risk management system, which provides the bank with critical intelligence. I've discovered the disturbing truth that this has been happening since the 90s and nobody really has evidence the system is getting the correct data! Without going into details, an issue arose on Friday that was so horrible I actually stormed out of the place. I was ready to quit, but I decided to just get out to calm my nerves and possibly go back Monday. I've been reflecting today on how to handle this. I have realized that, in probably less than 6 months, I could (with 2 other developers) remake a large component of this system. The new system would provide them with, as primary benefits, a maintainable codebase less prone to error and a solid QA framework. To do it properly I would have to be outside the bank, the internal bureaucracy is just too much. And moreover, I think a bank is fundamentally not a place that can make good software. This is my plan. Write a report explaining in depth all the problems with their current system Explain why their software practices fail and generate a tremendous amount of error and waste. Use this as the basis for claiming the project must be developed externally. Write a high level development plan, including what resources I will require Hand 1,2,3 to my manager, hopefully he passes it up the chain. Worst case he fires me, but this isn't so bad. Convinced Executive decides to award my company a contract for the new system I have 8 years experience as a software contractor and have delivered my share of successful software products, but all working in-house for small/medium sized companies. When I read this over, I think I have a dynamite plan. But since this is the first time doing something this bold so I have my doubts. My question is, is this a good idea? If you think not, please spare no detail.

    Read the article

  • Need an end of lexical scope action which can die normally

    - by Schwern
    I need the ability to add actions to the end of a lexical block where the action might die. And I need the exception to be thrown normally and be able to be caught normally. Unfortunately, Perl special cases exceptions during DESTROY both by adding "(in cleanup)" to the message and making them untrappable. For example: { package Guard; use strict; use warnings; sub new { my $class = shift; my $code = shift; return bless $code, $class; } sub DESTROY { my $self = shift; $self->(); } } use Test::More tests => 2; my $guard_triggered = 0; ok !eval { my $guard = Guard->new( #line 24 sub { $guard_triggered++; die "En guarde!" } ); 1; }, "the guard died"; is $@, "En guarde! at $@ line 24\n", "with the right error message"; is $guard_triggered, 1, "the guard worked"; I want that to pass. Currently the exception is totally swallowed by the eval. This is for Test::Builder2, so I cannot use anything but pure Perl. The underlying issue is I have code like this: { $self->setup; $user_code->(); $self->cleanup; } That cleanup must happen even if the $user_code dies, else $self gets into a weird state. So I did this: { $self->setup; my $guard = Guard->new(sub { $self->cleanup }); $user_code->(); } The complexity comes because the cleanup runs arbitrary user code and it is a use case where that code will die. I expect that exception to be trappable and unaltered by the guard. I'm avoiding wrapping everything in eval blocks because of the way that alters the stack.

    Read the article

  • FASM vc MASM trasnlation problem in mov si, offset msg

    - by Ruben Trancoso
    hi folks, just did my first test with MASM and FASM with the same code (almos) and I falled in trouble. The only difference is that to produce just the 104 bytes I need to write to MBR in FASM I put org 7c00h and in MASM 0h. The problem is on the mov si, offset msg that in the first case transletes it to 44 7C (7c44h) and with masm translates to 44 00 (0044h)! but just when I change org 7c00h to org 0h in MASM. Otherwise it will produce the entire segment from 0 to 7dff. how do I solve it? or in short, how to make MASM produce a binary that begins at 7c00h as it first byte and subsequent jumps remain relative to 7c00h? .model TINY .code org 7c00h ; Boot entry point. Address 07c0:0000 on the computer memory xor ax, ax ; Zero out ax mov ds, ax ; Set data segment to base of RAM jmp start ; Jump to the first byte after DOS boot record data ; ---------------------------------------------------------------------- ; DOS boot record data ; ---------------------------------------------------------------------- brINT13Flag db 90h ; 0002h - 0EH for INT13 AH=42 READ brOEM db 'MSDOS5.0' ; 0003h - OEM name & DOS version (8 chars) brBPS dw 512 ; 000Bh - Bytes/sector brSPC db 1 ; 000Dh - Sectors/cluster brResCount dw 1 ; 000Eh - Reserved (boot) sectors brFATs db 2 ; 0010h - FAT copies brRootEntries dw 0E0h ; 0011h - Root directory entries brSectorCount dw 2880 ; 0013h - Sectors in volume, < 32MB brMedia db 240 ; 0015h - Media descriptor brSPF dw 9 ; 0016h - Sectors per FAT brSPH dw 18 ; 0018h - Sectors per track brHPC dw 2 ; 001Ah - Number of Heads brHidden dd 0 ; 001Ch - Hidden sectors brSectors dd 0 ; 0020h - Total number of sectors db 0 ; 0024h - Physical drive no. db 0 ; 0025h - Reserved (FAT32) db 29h ; 0026h - Extended boot record sig brSerialNum dd 404418EAh ; 0027h - Volume serial number (random) brLabel db 'OSAdventure' ; 002Bh - Volume label (11 chars) brFSID db 'FAT12 ' ; 0036h - File System ID (8 chars) ;------------------------------------------------------------------------ ; Boot code ; ---------------------------------------------------------------------- start: mov si, offset msg call showmsg hang: jmp hang msg db 'Loading...',0 showmsg: lodsb cmp al, 0 jz showmsgd push si mov bx, 0007 mov ah, 0eh int 10h pop si jmp showmsg showmsgd: retn ; ---------------------------------------------------------------------- ; Boot record signature ; ---------------------------------------------------------------------- dw 0AA55h ; Boot record signature END

    Read the article

  • INNER JOIN code calculated value with SELECT statement

    - by sp-1986
    I have the following stored procedure which will generate mon to sun and then creates a temp table with a series of 'weeks' (start and end weeks) : USE [test_staff] GO /****** Object: StoredProcedure [dbo].[sp_timesheets_all_staff_by_week_by_job_grouping_by_site] Script Date: 03/21/2012 09:04:49 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE [dbo].[sp_timesheets_all_staff_by_week_by_job_grouping_by_site] ( @grouping_ref int, @week_ref int ) AS CREATE TABLE #WeeklyList ( Start_Week date, End_Week date, week_ref int --month_name date ) DECLARE @REPORT_DATE DATETIME, @WEEK_BEGINING VARCHAR(10) SELECT @REPORT_DATE = '2011-01-19T00:00:00' --SELECT @REPORT_DATE = GETDATE() -- should grab the date now. SELECT @WEEK_BEGINING = 'MONDAY' IF @WEEK_BEGINING = 'MONDAY' SET DATEFIRST 1 ELSE IF @WEEK_BEGINING = 'TUESDAY' SET DATEFIRST 2 ELSE IF @WEEK_BEGINING = 'WEDNESDAY' SET DATEFIRST 3 ELSE IF @WEEK_BEGINING = 'THURSDAY' SET DATEFIRST 4 ELSE IF @WEEK_BEGINING = 'FRIDAY' SET DATEFIRST 5 ELSE IF @WEEK_BEGINING = 'SATURDAY' SET DATEFIRST 6 ELSE IF @WEEK_BEGINING = 'SUNDAY' SET DATEFIRST 7 DECLARE @WEEK_START_DATE DATETIME, @WEEK_END_DATE DATETIME --GET THE WEEK START DATE SELECT @WEEK_START_DATE = @REPORT_DATE - (DATEPART(DW, @REPORT_DATE) - 1) --GET THE WEEK END DATE SELECT @WEEK_END_DATE = @REPORT_DATE + (7 - DATEPART(DW, @REPORT_DATE)) PRINT 'Week Start: ' + CONVERT(VARCHAR, @WEEK_START_DATE) PRINT 'Week End: ' + CONVERT(VARCHAR, @WEEK_END_DATE) DECLARE @Interval int = datediff(WEEK,getdate(),@WEEK_START_DATE)+1 --SELECT Start_Week=@WEEK_START_DATE --, End_Week=@WEEK_END_DATE --INTO #WeekList INSERT INTO #WeeklyList SELECT Start_Week=@WEEK_START_DATE, End_Week=@WEEK_END_DATE WHILE @Interval <= 0 BEGIN set @WEEK_START_DATE=DATEADD(WEEK,1,@WEEK_START_DATE) set @WEEK_END_DATE=DATEADD(WEEK,1,@WEEK_END_DATE) INSERT INTO #WeeklyList values (@WEEK_START_DATE,@WEEK_END_DATE) SET @Interval += 1; END SELECT CONVERT(VARCHAR(11), Start_Week, 106) AS 'month_name', CONVERT(VARCHAR(11), End_Week, 106) AS 'End', DATEDIFF(DAY, 0, Start_Week) / 7 AS week_ref -- create the unique week reference number --'VIEW' AS month_name FROM #WeeklyList In this section i am creating the week_ref DATEDIFF(DAY, 0, Start_Week) / 7 AS week_ref -- create the unique week reference number I then need to combine it with this select code: DECLARE @YearString char(3) = CONVERT(char(3), SUBSTRING(CONVERT(char(5), @week_ref), 1, 3)) DECLARE @MonthString char(2) = CONVERT(char(2), SUBSTRING(CONVERT(char(5), @week_ref), 4, 2)) --Convert: DECLARE @Year int = CONVERT(int, @YearString) + 1200 DECLARE @Month int = CONVERT(int, @MonthString) **--THIS FILTERS THE REPORT** SELECT ts.staff_member_ref, sm.common_name, sm.department_name, DATENAME(MONTH, ts.start_dtm) + ' ' + DATENAME(YEAR, ts.start_dtm) AS month_name, ts.timesheet_cat_ref, cat.desc_long AS timesheet_cat_desc, grps.grouping_ref, grps.description AS grouping_desc, ts.task_ref, tsks.task_code, tsks.description AS task_desc, ts.site_ref, sits.description AS site_desc, ts.site_ref AS Expr1, CASE WHEN ts .status = 0 THEN 'Pending' WHEN ts .status = 1 THEN 'Booked' WHEN ts .status = 2 THEN 'Approved' ELSE 'Invalid Status' END AS site_status, ts.booked_time AS booked_time_sum, start_dtm, CONVERT(varchar(20), start_dtm, 108) + ' ' + CONVERT(varchar(20), start_dtm, 103) AS start_dtm_text, booked_time, end_dtm, CONVERT(varchar(20), end_dtm, 108) + ' ' + CONVERT(varchar(20), end_dtm, 103) AS end_dtm_text FROM timesheets AS ts INNER JOIN timesheet_categories AS cat ON ts.timesheet_cat_ref = cat.timesheet_cat_ref INNER JOIN timesheet_tasks AS tsks ON ts.task_ref = tsks.task_ref INNER JOIN timesheet_task_groupings AS grps ON tsks.grouping_ref = grps.grouping_ref INNER JOIN timesheet_sites AS sits ON ts.site_ref = sits.site_ref INNER JOIN vw_staff_members AS sm ON ts.staff_member_ref = sm.staff_member_ref WHERE (ts.status IN (1, 2)) AND (cat.is_leave_category = 0) GROUP BY ts.staff_member_ref, sm.common_name, sm.department_name, DATENAME(MONTH, ts.start_dtm), DATENAME(YEAR, ts.start_dtm), ts.timesheet_cat_ref, cat.desc_long, grps.grouping_ref, grps.description, ts.status, ts.booked_time, ts.task_ref, tsks.task_code, tsks.description, ts.site_ref, sits.description, ts.start_dtm, ts.end_dtm ORDER BY sm.common_name, timesheet_cat_desc, tsks.task_code, site_desc DROP TABLE #WeeklyList GO I want to pass the week_ref into the SELECT statement (refer to comment - THIS FILTERS THE REPORT) but the problem is week_ref isnt a valid column as its derived by code. Any ideas?

    Read the article

  • XPathNavigator in Silverlight

    - by vladimir
    I have a code library that makes heavy use of XPathNavigator to parse some specific xml document. The xml document is cross-referenced, meaning that an element can reference another which has not yet been encountered during parsing: <ElementA ...> <DependentElementX id="1234"> </ElementA> <ElementX id="1234" .../> The document doesn't really look like this, but the point is that 1) there is an xml schema that enforces the overall document structure, 2) elements inside the document can reference each other using some IDs, and 3) there is quite a few such cross references between different elements in the document. The document is parsed in two phases. In the first pass I walk through the document XPathDocument doc = ...; XPathNavigator nav = doc.CreateNavigator(); nav.MoveToRoot(); nav.MoveToFirstChild()... and occasionally 'bookmark' the current position (element) in the document using XPathNavigator.Clone() method. This gives me a lightweight instance of an XPathNavigator which I can store somewhere and use later to jump back to a particular place (element) in my document. Once I have enough information collected in the first pass (for example, I have made sure there is indeed an ElementX with an id='1234'), I jump back to saved bookmarks (using those saved XPathNavigators) and complete the parsing. Well, now I'm about to use this library in Silverlight 3.0 and to my horror the XPathNavigator is not in the System.Xml assembly. Questions: 1) Am I missing something obvious (i.e. XPathNavigator does exist in some shape or form, for example in a toolkit or a freeware library)? 2) If I do have to make modifications in the code, what would be the best way to go? Ideally, I would like to make minimal changes, not to rewrite 80% of the code just to be able to use something like XLinq. To resume, in case I have to give up XPathNavigator, all I need is a way to bookmark places in my document and to get back to them so that I can continue to iterate from where I left off. Thanks in advance for any help/ideas.

    Read the article

  • Strange behavior with Powershell scriptblock variable scope and modules, any suggestions?

    - by DanMan
    NOTE: I'm using PowerShell 2.0 on Windows Vista. I'm trying to add support for specifying build arguments to psake, but I've run into some strange PowerShell variable scoping behavior dealing specifically with calling functions that have been exported using Export-ModuleMember (which is how psake exposes it's main method). Following is a simple PowerShell module to illustrate (named repoCase.psm1): function Test { param( [Parameter(Position=0,Mandatory=0)] [scriptblock]$properties = {} ) $defaults = {$message = "Hello, world!"} Write-Host "Before running defaults, message is: $message" . $defaults #At this point, $message is correctly set to "Hellow, world!" Write-Host "Aftering running defaults, message is: $message" . $properties #At this point, I would expect $message to be set to whatever is passed in, #which in this case is "Hello from poperties!", but it isn't. Write-Host "Aftering running properties, message is: $message" } Export-ModuleMember -Function "Test" To test the module, run the following sequence of commands (be sure you're in the same directory as the repoCase.psm1): Import-Module .\repoCase.psm1 #Note that $message should be null Write-Host "Before execution - In global scope, message is: $message" Test -properties { "Executing properties, message is $message"; $message = "Hello from properties!"; } #Now $message is set to the value from the script block. The script block affected only the global scope. Write-Host "After execution - In global scope, message is: $message" Remove-Module repoCase The behavior I expected was for the script block I passed to Test to affect the local scope of Test. It is being 'dotsourced' in, so any changes it makes should be within the scope of the caller. However, that's not what's happening, it seems to be affecting the scope of where it was declared. Here's the output: Before execution - In global scope, message is: Before running defaults, message is: Aftering running defaults, message is: Hello, world! Executing properties, message is Aftering running properties, message is: Hello, world! After execution - In global scope, message is: Hello from properties! Interestingly, if I don't export Test as a module and instead just declare the function and invoke it, everything works just like I would expect it to. The script block affects only Test's scope, and does not modify the global scope. I'm not a PowerShell guru, but can someone explain this behavior to me?

    Read the article

  • Rails "NoMethodError" with sub-resources

    - by Tchock
    Hi. I'm a newbie Rails developer who is getting the following error when trying to access the 'new' action on my CityController: undefined method `cities_path' for #<#<Class:0x104608c18>:0x104606f08> Extracted source (around line #2): 1: <h1>New City</h1> 2: <%= form_for(@city) do |f| %> 3: <%= f.error_messages %> 4: 5: <div class="field"> As some background, I have a State model with many Cities. I'm getting this error after clicking on the following link coming from a State show page: <p>Add a city: <%= link_to "Add city", new_state_city_path(@state) %></p> When I run 'rake:routes' it says this is a legit route... For more background, here is the CityController 'new' action: def new @city = City.new respond_to do |format| format.html # new.html.erb format.xml { render :xml => @city } end end Here is the (complete) form in the view: <%= form_for(@city) do |f| %> <%= f.error_messages %> <div class="field"> <%= f.label :name %><br /> <%= f.text_field :name %> </div> <div class="actions"> <%= f.submit %> </div> <% end %> This initially made me think that it's a resources/routes issue since it came back with a mention of 'cities_path' (in fact, that's what another person posting to Stack Overflow had wrong (http://stackoverflow.com/questions/845315/rails-error-nomethoderror-my-first-ruby-app). However, that doesn't seem to be the case from what I can see. Here are how my resources look in my routes file: resources :states do resources :cities end I can get it working when they are not sub-resources, but I really need to keep them as sub-resources for my future plans with the app. Any help would be very much appreciated, since I've been racking my brains on this for more hours than I would care to admit... Thanks! (Not sure this matters at all, but I'm running the very latest version of Rails 3 beta2).

    Read the article

  • JavaScript: Given an offset and substring length in an HTML string, what is the parent node?

    - by Bungle
    My current project requires locating an array of strings within an element's text content, then wrapping those matching strings in <a> elements using JavaScript (requirements simplified here for clarity). I need to avoid jQuery if at all possible - at least including the full library. For example, given this block of HTML: <div> <p>This is a paragraph of text used as an example in this Stack Overflow question.</p> </div> and this array of strings to match: ['paragraph', 'example'] I would need to arrive at this: <div> <p>This is a <a href="http://www.example.com/">paragraph</a> of text used as an <a href="http://www.example.com/">example</a> in this Stack Overflow question.</p> </div> I've arrived at a solution to this by using the innerHTML() method and some string manipulation - basically using the offsets (via indexOf()) and lengths of the strings in the array to break the HTML string apart at the appropriate character offsets and insert <a href="http://www.example.com/"> and </a> tags where needed. However, an additional requirement has me stumped. I'm not allowed to wrap any matched strings in <a> elements if they're already in one, or if they're a descendant of a heading element (<h1> to <h6>). So, given the same array of strings above and this block of HTML (the term matching has to be case-insensitive, by the way): <div> <h1>Example</a> <p>This is a <a href="http://www.example.com/">paragraph of text</a> used as an example in this Stack Overflow question.</p> </div> I would need to disregard both the occurrence of "Example" in the <h1> element, and the "paragraph" in <a href="http://www.example.com/">paragraph of text</a>. This suggests to me that I have to determine which node each matched string is in, and then traverse its ancestors until I hit <body>, checking to see if I encounter a <a> or <h_> node along the way. Firstly, does this sound reasonable? Is there a simpler or more obvious approach that I've failed to consider? It doesn't seem like regular expressions or another string-based comparison to find bounding tags would be robust - I'm thinking of issues like self-closing elements, irregularly nested tags, etc. There's also this... Secondly, is this possible, and if so, how would I approach it?

    Read the article

  • UIIMageView, warning: check_safe_call: could not restore current frame

    - by lukya
    Hi, I am changing the image in UIImageView based on accelerometer input. The images are stored in an array. The application runs fine for a while and then crashes. warning: check_safe_call: could not restore current frame I am not using "UIImage ImageNamed" method when populating the array. The total size of all images is around 12 Mb. But individual images are very light (<100 kb) and i am using only one image at a time from the array. Just in case there are any autoreleases, I have allocated a NSAutoreleasePool in view did load and am draining it in the didReceiveMemoryWarning method (which does get called 2, 3 times before the app crashes?). Following is the code that creates images array: //create autorelease pool as we are creating many autoreleased objects NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSMutableArray *finalarr = [[NSMutableArray alloc] initWithCapacity:9]; NSLog(@"start loading"); for(int y = 0; y < 100; y+=10) { NSMutableArray *arr = [[NSMutableArray alloc] initWithCapacity:10]; for(int x = 0; x < 10; x++) { NSString *imageName = [[NSString alloc] initWithFormat:@"0%d",y + x]; UIImage *img = [[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:imageName ofType:@"png"]]; [arr addObject:img]; [imageName release]; [img release]; } [finalarr addObject:arr]; [arr release]; } NSLog(@"done loading"); // Override point for customization after app launch viewController.imagesArray = finalarr; [finalarr release]; //retain the array of images [viewController.imagesArray retain]; //release the aurtorelease pool to free memory taken up by objects enqued for release [pool release]; As the app runs smoothly for a while, which means array creation is definitely not the problem. After this the following method is called from [accelerometer didAccelerate] -(BOOL)setImageForX:(int)x andY:(int)y { [self.imageView setImage:(UIImage*)[(NSArray*)[self.imagesArray objectAtIndex:y] objectAtIndex:x]]; return TRUE; } So the only code being executed is the "UIImageView setImage". But no objects are being created here. Please let me know if the code seems to have any leaks or i am doing something wrong. Thanks, Swapnil

    Read the article

  • Xpath help. Get childnode with variable name

    - by Kim Andersen
    I have the following XML: <StatsContainer> <Variant1>0</Variant1> <Variant2>0.5</Variant2> <Variant3>1.2</Variant3> <Variant4>4.1</Variant4> <Variant5>93.9</Variant5> <Variant6>0.3</Variant6> <Variant7>0</Variant7> <Variant8>0</Variant8> <Variant9>0</Variant9> <Variant10>0</Variant10> <Variant11>0</Variant11> <Variant12>0</Variant12> <GlobalVariant1>4.6</GlobalVariant1> <GlobalVariant2>40.4</GlobalVariant2> <GlobalVariant3>13.8</GlobalVariant3> <GlobalVariant4>2.8</GlobalVariant4> <GlobalVariant5>35.6</GlobalVariant5> <GlobalVariant6>2.8</GlobalVariant6> <GlobalVariant7>0</GlobalVariant7> <GlobalVariant8>0</GlobalVariant8> <GlobalVariant9>0</GlobalVariant9> <GlobalVariant10>0</GlobalVariant10> <GlobalVariant11>0</GlobalVariant11> <GlobalVariant12>0</GlobalVariant12> <MosaicType>Boligtype</MosaicType> <OverRepresentedVariant>5</OverRepresentedVariant> </StatsContainer> As you can see I have a number in the "OverRepresentedVariant"-tag. This number can change from time to time. What i Need is to grab the "Variant"-tag with the right number. In the above case I need to get the value from the "Variant5"-tag (93.9). Tomorrow the "OverRepresentedVariant"-value might have changed to 3, this would mean that I should now grab the "Variant3"-value instead. So this is what I got. I have a variable called $btOver which contains the above XML. I also have a variable called $btId which contains the "OverRepresentedVariant"-value like this: <xsl:variable name="btId" select="$btOver/OverRepresentedVariant" /> So now I need some help finding the Variant-tags with the right ID. The tags that I need will always be named "Variant" followed by an id. So how can I get the right tag? Thanks a lot in advance folks. /Kim Andersen

    Read the article

  • Changing the itemsSource of a treeview makes it's children invisible, when they were already display

    - by Marnix Kraus
    I found some strange problem in WPF, using the itemsSource of a treeview. I hope I can make this specific problem clear for you. First; a story. There is a treeview. It has a list with treeviewitems as itemsSource. This list is called _roots. There is another list, called _leafs. For as in a treeview, the _roots contain the _leafs in some hierarchical way. For example: <TreeviewItem Header="Jungle"> <TreeviewItem> <SpecialTreeviewItem Header="Monkey"/> <SpecialTreeviewItem Header="Apple"/> </TreeviewItem> </TreeviewItem> Now I am trying to switch between these two lists as itemsSource. It seemed to work fine, but it doesn't: When the Jungle-item is un-expanded, and I change the itemsSource to _leafs, and change it back again to _roots, everything works fine and all items can be expanded and showed. But when the Jungle-item is expanded (and the special items are already visible) and I change it to the _leafs itemsSource, and then change the itemsSource back to _roots, all special items have disappeared!! Also, when I do the same as case 2, but first un-expand the Jungle-item again, the special items also disappear. I did a lot of debugging, before posting this question here and come to the following conclusion: Printing on the event: visibility changed, the visibility is set to false for all items that were already visible (that is, when _roots become visible, the special items become invisible (because they were already visible)) So, IsVisible is false for the items, but Visibility = Visible. Which is a bit strange. The problem seems to depend on the use of the _roots list, which in a certain way contain the _leafs. When I change the itemsSource to different lists with special items in it, everything works fine. The hierarchical structure of the _roots make this thing broken. I hope that this is a complete overview of my problem. Help would be appreciated.

    Read the article

  • "Simple" sort a nested array using array_multisort or native PHP functions instead of my own foreach loop

    - by Ana Ban
    I have the following array of days of the week, with each day having hours of the day (the whole array represents the schedule of a part-time employee): Array ( [7] => Array ( [0] => 15 [1] => 14 [2] => 13 [3] => 11 [4] => 12 [5] => 10 ) [1] => Array ( [0] => 10 [1] => 13 [2] => 12 ) [6] => Array ( [0] => 14 ) [3] => Array ( [0] => 4 [1] => 5 [2] => 6 ) ) and I simply need to: sort asc each sub-array (2nd dimension) - no need to maintain the numeric keys, values are integers sort asc the 1st dimension and maintain the numeric, integer keys ie: Array ( [1] => Array ( [0] => 10 [1] => 12 [2] => 13 ) [3] => Array ( [0] => 4 [1] => 5 [2] => 6 ) [6] => Array ( [0] => 14 ) [7] => Array ( [0] => 10 [1] => 11 [2] => 12 [3] => 13 [4] => 14 [5] => 15 ) ) Additional info: only the keys of the 1st dimension and the values of the 2nd dimension (and of course their association) are meaningful to my use-case the 1st dimension can have at most 7 values, ranging from 1-7 (days of the week), and will have at least 1 value (1 day) the 2nd dimension can have at most 24 values, ranging from 0-23 (hours of each day), and will have at least 1 value (1 hour per day) I know I can do this with a foreach on the whole ksorted array and sort each 2nd dimension array: ksort($sched); foreach ($sched as &$array) sort($array); unset($array); but I was hoping I could achieve this with native php array function(s) instead. My search led me to try array_multisort(array_values($array), array_keys($array), $array) but I just can't make it work.

    Read the article

  • how to implement a "soft barrier" in multithreaded c++

    - by Jason
    I have some multithreaded c++ code with the following structure: do_thread_specific_work(); update_shared_variables(); //checkpoint A do_thread_specific_work_not_modifying_shared_variables(); //checkpoint B do_thread_specific_work_requiring_all_threads_have_updated_shared_variables(); What follows checkpoint B is work that could have started if all threads have reached only checkpoint A, hence my notion of a "soft barrier". Typically multithreading libraries only provide "hard barriers" in which all threads must reach some point before any can continue. Obviously a hard barrier could be used at checkpoint B. Using a soft barrier can lead to better execution time, especially since the work between checkpoints A and B may not be load-balanced between the threads (i.e. 1 slow thread who has reached checkpoint A but not B could be causing all the others to wait at the barrier just before checkpoint B). I've tried using atomics to synchronize things and I know with 100% certainty that is it NOT guaranteed to work. For example using openmp syntax, before the parallel section start with: shared_thread_counter = num_threads; //known at compile time #pragma omp flush Then at checkpoint A: #pragma omp atomic shared_thread_counter--; Then at checkpoint B (using polling): #pragma omp flush while (shared_thread_counter > 0) { usleep(1); //can be removed, but better to limit memory bandwidth #pragma omp flush } I've designed some experiments in which I use an atomic to indicate that some operation before it is finished. The experiment would work with 2 threads most of the time but consistently fail when I have lots of threads (like 20 or 30). I suspect this is because of the caching structure of modern CPUs. Even if one thread updates some other value before doing the atomic decrement, it is not guaranteed to be read by another thread in that order. Consider the case when the other value is a cache miss and the atomic decrement is a cache hit. So back to my question, how to CORRECTLY implement this "soft barrier"? Is there any built-in feature that guarantees such functionality? I'd prefer openmp but I'm familiar with most of the other common multithreading libraries. As a workaround right now, I'm using a hard barrier at checkpoint B and I've restructured my code to make the work between checkpoint A and B automatically load-balancing between the threads (which has been rather difficult at times). Thanks for any advice/insight :)

    Read the article

  • Insertions into Zipper trees on XML files in Clojure

    - by ivar
    I'm confused as how to idiomatically change a xml tree accessed through clojure.contrib's zip-filter.xml. Should be trying to do this at all, or is there a better way? Say that I have some dummy xml file "itemdb.xml" like this: <itemlist> <item id="1"> <name>John</name> <desc>Works near here.</desc> </item> <item id="2"> <name>Sally</name> <desc>Owner of pet store.</desc> </item> </itemlist> And I have some code: (require '[clojure.zip :as zip] '[clojure.contrib.duck-streams :as ds] '[clojure.contrib.lazy-xml :as lxml] '[clojure.contrib.zip-filter.xml :as zf]) (def db (ref (zip/xml-zip (lxml/parse-trim (java.io.File. "itemdb.xml"))))) ;; Test that we can traverse and parse. (doall (map #(print (format "%10s: %s\n" (apply str (zf/xml-> % :name zf/text)) (apply str (zf/xml-> % :desc zf/text)))) (zf/xml-> @db :item))) ;; I assume something like this is needed to make the xml tags (defn create-item [name desc] {:tag :item :attrs {:id "3"} :contents (list {:tag :name :attrs {} :contents (list name)} {:tag :desc :attrs {} :contents (list desc)})}) (def fred-item (create-item "Fred" "Green-haired astrophysicist.")) ;; This disturbs the structure somehow (defn append-item [xmldb item] (zip/insert-right (-> xmldb zip/down zip/rightmost) item)) ;; I want to do something more like this (defn append-item2 [xmldb item] (zip/insert-right (zip/rightmost (zf/xml-> xmldb :item)) item)) (dosync (alter db append-item2 fred-item)) ;; Save this simple xml file with some added stuff. (ds/spit "appended-itemdb.xml" (with-out-str (lxml/emit (zip/root @db) :pad true))) I am unclear about how to use the clojure.zip functions appropriately in this case, and how that interacts with zip-filter. If you spot anything particularly weird in this small example, please point it out.

    Read the article

  • How to pass ctor args in Activator.CreateInstance?

    - by thames
    I need a performance enhanced Activator.CreateInstance() and came across this article by Miron Abramson that uses a factory to create the instance in IL and then cache it. (I've included code below from Miron Abramson's site in case it somehow disappears). I'm new to IL Emit code and anything beyond Activator.CreateInstance() for instantiating a class and any help would be much appreciative. My problem is that I need to create an instance of an object that takes a ctor with a parameter. I see there is a way to pass in the Type of the parameter, but is there a way to pass in the value of the ctor parameter as well? If possible, I would like to use a method similar to CreateObjectFactory<T>(params object[] constructorParams) as some objects I want to instantiate may have more than 1 ctor param. // Source: http://mironabramson.com/blog/post/2008/08/Fast-version-of-the-ActivatorCreateInstance-method-using-IL.aspx public static class FastObjectFactory { private static readonly Hashtable creatorCache = Hashtable.Synchronized(new Hashtable()); private readonly static Type coType = typeof(CreateObject); public delegate object CreateObject(); /// /// Create an object that will used as a 'factory' to the specified type T /// public static CreateObject CreateObjectFactory() where T : class { Type t = typeof(T); FastObjectFactory.CreateObject c = creatorCache[t] as FastObjectFactory.CreateObject; if (c == null) { lock (creatorCache.SyncRoot) { c = creatorCache[t] as FastObjectFactory.CreateObject; if (c != null) { return c; } DynamicMethod dynMethod = new DynamicMethod("DM$OBJ_FACTORY_" + t.Name, typeof(object), null, t); ILGenerator ilGen = dynMethod.GetILGenerator(); ilGen.Emit(OpCodes.Newobj, t.GetConstructor(Type.EmptyTypes)); ilGen.Emit(OpCodes.Ret); c = (CreateObject)dynMethod.CreateDelegate(coType); creatorCache.Add(t, c); } } return c; } } Update to Miron's code from commentor on his post 2010-01-11 public static class FastObjectFactory2<T> where T : class, new() { public static Func<T> CreateObject { get; private set; } static FastObjectFactory2() { Type objType = typeof(T); var dynMethod = new DynamicMethod("DM$OBJ_FACTORY_" + objType.Name, objType, null, objType); ILGenerator ilGen = dynMethod.GetILGenerator(); ilGen.Emit(OpCodes.Newobj, objType.GetConstructor(Type.EmptyTypes)); ilGen.Emit(OpCodes.Ret); CreateObject = (Func<T>) dynMethod.CreateDelegate(typeof(Func<T>)); } }

    Read the article

  • Correct way of using/testing event service in Eclipse E4 RCP

    - by Thorsten Beck
    Allow me to pose two coupled questions that might boil down to one about good application design ;-) What is the best practice for using event based communication in an e4 RCP application? How can I write simple unit tests (using JUnit) for classes that send/receive events using dependency injection and IEventBroker ? Let’s be more concrete: say I am developing an Eclipse e4 RCP application consisting of several plugins that need to communicate. For communication I want to use the event service provided by org.eclipse.e4.core.services.events.IEventBroker so my plugins stay loosely coupled. I use dependency injection to inject the event broker to a class that dispatches events: @Inject static IEventBroker broker; private void sendEvent() { broker.post(MyEventConstants.SOME_EVENT, payload) } On the receiver side, I have a method like: @Inject @Optional private void receiveEvent(@UIEventTopic(MyEventConstants.SOME_EVENT) Object payload) Now the questions: In order for IEventBroker to be successfully injected, my class needs access to the current IEclipseContext. Most of my classes using the event service are not referenced by the e4 application model, so I have to manually inject the context on instantiation using e.g. ContextInjectionFactory.inject(myEventSendingObject, context); This approach works but I find myself passing around a lot of context to wherever I use the event service. Is this really the correct approach to event based communication across an E4 application? how can I easily write JUnit tests for a class that uses the event service (either as a sender or receiver)? Obviously, none of the above annotations work in isolation since there is no context available. I understand everyone’s convinced that dependency injection simplifies testability. But does this also apply to injecting services like the IEventBroker? This article describes creation of your own IEclipseContext to include the process of DI in tests. Not sure if this could resolve my 2nd issue but I also hesitate running all my tests as JUnit Plug-in tests as it appears impractible to fire up the PDE for each unit test. Maybe I just misunderstand the approach. This article speaks about “simply mocking IEventBroker”. Yes, that would be great! Unfortunately, I couldn’t find any information on how this can be achieved. All this makes me wonder whether I am still on a "good path" or if this is already a case of bad design? And if so, how would you go about redesigning? Move all event related actions to dedicated event sender/receiver classes or a dedicated plugin?

    Read the article

  • get_or_create generic relations in Django & python debugging in general

    - by rabidpebble
    I ran the code to create the generically related objects from this demo: http://www.djangoproject.com/documentation/models/generic_relations/ Everything is good intially: >>> bacon.tags.create(tag="fatty") <TaggedItem: fatty> >>> tag, newtag = bacon.tags.get_or_create(tag="fatty") >>> tag <TaggedItem: fatty> >>> newtag False But then the use case that I'm interested in for my app: >>> tag, newtag = bacon.tags.get_or_create(tag="wholesome") Traceback (most recent call last): File "<console>", line 1, in <module> File "/usr/local/lib/python2.6/dist-packages/django/db/models/manager.py", line 123, in get_or_create return self.get_query_set().get_or_create(**kwargs) File "/usr/local/lib/python2.6/dist-packages/django/db/models/query.py", line 343, in get_or_create raise e IntegrityError: app_taggeditem.content_type_id may not be NULL I tried a bunch of random things after looking at other code: >>> tag, newtag = bacon.tags.get_or_create(tag="wholesome", content_type=TaggedItem) ValueError: Cannot assign "<class 'generics.app.models.TaggedItem'>": "TaggedItem.content_type" must be a "ContentType" instance. or: >>> tag, newtag = bacon.tags.get_or_create(tag="wholesome", content_type=TaggedItem.content_type) InterfaceError: Error binding parameter 3 - probably unsupported type. etc. I'm sure somebody can give me the correct syntax, but the real problem here is that I have no idea what is going on. I have developed in strongly typed languages for over ten years (x86 assembly, C++ and C#) but am new to Python. I find it really difficult to follow what is going on in Python when things like this break. In the languages I mentioned previously it's fairly straightforward to figure things like this out -- check the method signature and check your parameters. Looking at the Django documentation for half an hour left me just as lost. Looking at the source for get_or_create(self, **kwargs) didn't help either since there is no method signature and the code appears very generic. A next step would be to debug the method and try to figure out what is happening, but this seems a bit extreme... I seem to be missing some fundamental operating principle here... what is it? How do I resolve issues like this on my own in the future?

    Read the article

  • fetching rows from mysql table and displaying them as JGROWL notifications

    - by jeansymolanza
    hey guys, i am having problems implementing my php/mysql code into a jgrowl if you are familiar with jgrowl you will know it delivers notifications like Growl does for OS X i am trying to get it read all the records from my table but at the moment it is only displaying one record as a notification and it loops through it 4 times another problem is that if i have 5 rows in the table then jgrowl will only display 4 notifications are going to be viewed how do i get it to view all the records in the table as notifications and how do i display the total number of records (5) as notifications and account for the missing one at the moment thanking you guys in advance... God bless <script type="text/javascript"> // In case you don't have firebug... if (!window.console || !console.firebug) { var names = ["log", "debug", "info", "warn", "error", "assert", "dir", "dirxml", "group", "groupEnd", "time", "timeEnd", "count", "trace", "profile", "profileEnd"]; window.console = {}; for (var i = 0; i < names.length; ++i) window.console[names[i]] = function() {}; } (function($){ $(document).ready(function(){ // This specifies how many messages can be pooled out at any given time. // If there are more notifications raised then the pool, the others are // placed into queue and rendered after the other have disapeared. $.jGrowl.defaults.pool = 5; var i = 1; var y = 1; setInterval( function() { if ( i < <?php echo $totalRows_comment; ?> ) { <?php echo '$.jGrowl("'.$row_comment['comment'].'",'; ?> { sticky: true, log: function() { console.log("Creating message " + i + "..."); }, beforeOpen: function() { console.log("Rendering message " + y + "..."); y++; } }); } i++; } , 1000 ); }); })(jQuery); </script> <p> </span> <p>

    Read the article

  • _heapwalk reports _HEAPBADNODE, causes breakpoint or loops endlessly

    - by Stefan Hubert
    I use _heapwalk to gather statistics about the Process' standard heap. Under certain circumstances i observe unexpected behaviours like: _HEAPBADNODE is returned some breakpoint is triggered inside _heapwalk, telling me the heap might got corrupted access violation inside _heapWalk. I saw different behaviours on different Computers. On one Windows XP 32 bit machine everything looked fine, whereas on two Windows XP 64 bit machines i saw the mentioned symptoms. I saw this behaviour only if LowFragmentationHeap was enabled. I played around a bit. I walked the heap several times right one after another inside my program. First time doing nothing in between the subsequent calls to _heapWalk (everything fine). Then again, this time doing some stuff (for gathering statistics) in between two subsequent calls to _heapWalk. Depending upon what I did there, I sometimes got the described symptoms. Here finally a question: What exactly is safe and what is not safe to do in between two subsequent calls to _heapWalk during a complete heap walk run? Naturally, i shall not manipulate the heap. Therefore i doublechecked that i don't call new and delete. However, my observation is that function calls with some parameter passing causes my heap walk run to fail already. I subsequently added function calls and increasing number of parameters passed to these. My feeling was two function calls with two paramters being passed did not work anymore. However I would like to know why. Any ideas why this does not happen on some machines? Any ideas why this only happens if LowFragmentationHeap is enabled? Sample Code finally: #include <malloc.h> void staticMethodB( int a, int b ) { } void staticMethodA( int a, int b, int c) { staticMethodB( 3, 6); return; } ... _HEAPINFO hinfo; hinfo._pentry = NULL; while( ( heapstatus = _heapwalk( &hinfo ) ) == _HEAPOK ) { //doing nothing here works fine //however if i call functions here with parameters, this causes //_HEAPBADNODE or something else staticMethodA( 3,4,5); } switch( heapstatus ) { ... case _HEAPBADNODE: assert( false ); /*ERROR - bad node in heap */ break; ...

    Read the article

  • Binary Search Help

    - by aloh
    Hi, for a project I need to implement a binary search. This binary search allows duplicates. I have to get all the index values that match my target. I've thought about doing it this way if a duplicate is found to be in the middle: Target = G Say there is this following sorted array: B, D, E, F, G, G, G, G, G, G, Q, R S, S, Z I get the mid which is 7. Since there are target matches on both sides, and I need all the target matches, I thought a good way to get all would be to check mid + 1 if it is the same value. If it is, keep moving mid to the right until it isn't. So, it would turn out like this: B, D, E, F, G, G, G, G, G, G (MID), Q, R S, S, Z Then I would count from 0 to mid to count up the target matches and store their indexes into an array and return it. That was how I was thinking of doing it if the mid was a match and the duplicate happened to be in the mid the first time and on both sides of the array. Now, what if it isn't a match the first time? For example: B, D, E, F, G, G, J, K, L, O, Q, R, S, S, Z Then as normal, it would grab the mid, then call binary search from first to mid-1. B, D, E, F, G, G, J Since G is greater than F, call binary search from mid+1 to last. G, G, J. The mid is a match. Since it is a match, search from mid+1 to last through a for loop and count up the number of matches and store the match indexes into an array and return. Is this a good way for the binary search to grab all duplicates? Please let me know if you see problems in my algorithm and hints/suggestions if any. The only problem I see is that if all the matches were my target, I would basically be searching the whole array but then again, if that were the case I still would need to get all the duplicates. Thank you BTW, my instructor said we cannot use Vectors, Hash or anything else. He wants us to stay on the array level and get used to using them and manipulating them.

    Read the article

  • Referencing both an old version and new version of the same DLL (VB.Net)

    - by ckittel
    Consider the following situation: WidgetCompany produced a .NET DLL in 2006 called Widget.dll, version 1.0. I consumed this Widget.dll file throughout my VB.Net application. Over time, WidgetCompany has been updating Widget.dll, I never bothered to keep up, continuing to ship version 1.0 of Widget.dll with my software. It's now 2010, my project is now a VB.Net 3.5 application and WidgetCompany has come out with Widget.dll version 3.0. It looks and functions almost identical to Widget.dll version 1.0, using all the same namespaces and type names from before. However, Widget.dll version 3.0 has many run-time breaking changes since 1.0 and I cannot simply cut over to the new version; however, I don't want to continue developing against the 1.0 version and therefore keep digging myself deeper in the hole. What I want to do is do all new development in my project with Widget.dll version 3.0, whilst keeping Widget.dll version 1.0 around until I find time to convert all of my 1.0 consumption to the newer 3.0 code. Now, for starters, I obviously cannot simply reference both Widget.dll (Ver 1.0) and Widget.dll (Ver 3.0) in Visual Studio. Doing so gives me the following message: "A reference to 'Widget.dll' could not be added. A reference to the component 'Widget' already exists in the project." To work around that, I can simply rename version 3.0 Widget.dll to Widget.3.dll. But this is where I'm stuck. Any attempts to reference types found in "the dll" leads to ambiguity and the compiler obviously doesn't have any clue as to what I really want in this or that case. Is there something I can do that gives a DLL a new "root" Namespace or something? For example, if I could say "Widget.dll has a new root namespace of Legacy" then I could update existing code to reference the types found in Legacy.<RootNamespace> namespace while all new code could simply reference types from the <RootNamespace> namespace. Pipe dream or reality? Are there other solutions to situations this (besides "don't get in this situation in the first place")?

    Read the article

  • How to optimize my PostgreSQL DB for prefix search?

    - by asmaier
    I have a table called "nodes" with roughly 1.7 million rows in my PostgreSQL db =#\d nodes Table "public.nodes" Column | Type | Modifiers --------+------------------------+----------- id | integer | not null title | character varying(256) | score | double precision | Indexes: "nodes_pkey" PRIMARY KEY, btree (id) I want to use information from that table for autocompletion of a search field, showing the user a list of the ten titles having the highest score fitting to his input. So I used this query (here searching for all titles starting with "s") =# explain analyze select title,score from nodes where title ilike 's%' order by score desc; QUERY PLAN ----------------------------------------------------------------------------------------------------------------------- Sort (cost=64177.92..64581.38 rows=161385 width=25) (actual time=4930.334..5047.321 rows=161264 loops=1) Sort Key: score Sort Method: external merge Disk: 5712kB -> Seq Scan on nodes (cost=0.00..46630.50 rows=161385 width=25) (actual time=0.611..4464.413 rows=161264 loops=1) Filter: ((title)::text ~~* 's%'::text) Total runtime: 5260.791 ms (6 rows) This was much to slow for using it with autocomplete. With some information from Using PostgreSQL in Web 2.0 Applications I was able to improve that with a special index =# create index title_idx on nodes using btree(lower(title) text_pattern_ops); =# explain analyze select title,score from nodes where lower(title) like lower('s%') order by score desc limit 10; QUERY PLAN ------------------------------------------------------------------------------------------------------------------------------------------ Limit (cost=18122.41..18122.43 rows=10 width=25) (actual time=1324.703..1324.708 rows=10 loops=1) -> Sort (cost=18122.41..18144.60 rows=8876 width=25) (actual time=1324.700..1324.702 rows=10 loops=1) Sort Key: score Sort Method: top-N heapsort Memory: 17kB -> Bitmap Heap Scan on nodes (cost=243.53..17930.60 rows=8876 width=25) (actual time=96.124..1227.203 rows=161264 loops=1) Filter: (lower((title)::text) ~~ 's%'::text) -> Bitmap Index Scan on title_idx (cost=0.00..241.31 rows=8876 width=0) (actual time=90.059..90.059 rows=161264 loops=1) Index Cond: ((lower((title)::text) ~>=~ 's'::text) AND (lower((title)::text) ~<~ 't'::text)) Total runtime: 1325.085 ms (9 rows) So this gave me a speedup of factor 4. But can this be further improved? What if I want to use '%s%' instead of 's%'? Do I have any chance of getting a decent performance with PostgreSQL in that case, too? Or should I better try a different solution (Lucene?, Sphinx?) for implementing my autocomplete feature?

    Read the article

  • Asynchronous vs Synchronous vs Threading in an iPhone App

    - by Coocoo4Cocoa
    I'm in the design stage for an app which will utilize a REST web service and sort of have a dilemma in as far as using asynchronous vs synchronous vs threading. Here's the scenario. Say you have three options to drill down into, each one having its own REST-based resource. I can either lazily load each one with a synchronous request, but that'll block the UI and prevent the user from hitting a back navigation button while data is retrieved. This case applies almost anywhere except for when your application requires a login screen. I can't see any reason to use synchronous HTTP requests vs asynchronous because of that reason alone. The only time it makes sense is to have a worker thread make your synchronous request, and notify the main thread when the request is done. This will prevent the block. The question then is bench marking your code and seeing which has more overhead, a threaded synchronous request or an asynchronous request. The problem with asynchronous requests is you need to either setup a smart notification or delegate system as you can have multiple requests for multiple resources happening at any given time. The other problem with them is if I have a class, say a singleton which is handling all of my data, I can't use asynchronous requests in a getter method. Meaning the following won't go: - (NSArray *)users { if(users == nil) users = do_async_request // NO GOOD return users; } whereas the following: - (NSArray *)users { if(users == nil) users == do_sync_request // OK. return users; } You also might have priority. What I mean by priority is if you look at Apple's Mail application on the iPhone, you'll notice they first suck down your entire POP/IMAP tree before making a second request to retrieve the first 2 lines (the default) of your message. I suppose my question to you experts is this. When are you using asynchronous, synchronous, threads -- and when are you using either async/sync in a thread? What kind of delegation system do you have setup to know what to do when a async request completes? Are you prioritizing your async requests? There's a gamut of solutions to this all too common problem. It's simple to hack something out. The problem is, I don't want to hack and I want to have something that's simple and easy to maintain.

    Read the article

< Previous Page | 851 852 853 854 855 856 857 858 859 860 861 862  | Next Page >