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• Can't control connection bit rate using iwconfig with Atheros TL-WN821N (AR7010)

  - by Paul H

  I'm trying to reduce the connection bit rate on my Atheros TP-Link TL-WN821N v3 usb wifi adapter due to frequent instability issues (reported connection speed goes down to 1Mb/s and I have to physically reconnect the adapter to regain a connection). I know this is a common problem with this device, and I have tried everything I can think of to fix it, including using drivers from linux-backports; compiling and installing a custom firmware (following instructions on https://wiki.debian.org/ath9k_htc#fw-free) and (as a last resort) using ndiswrapper. When using ndiswrapper, the wifi adapter is stable and operates in g mode at 54Mb/s (whilst when using the default ath9k_htc module, the adapter connects in n mode and the bit rate fluctuates constantly). Unfortunately, with this setup I have to run my processor using only one core, since using SMP with ndiswrapper causes a kernel oops on my system. So I want to lock my bit rate to 54Mb/s (or less, if need be) for connection stability, using the ath9k_htc module. I've tried 'sudo iwconfig wlan0 rate 54M'; the command runs with no error but when I check the bit rate with 'sudo iwlist wlan0 bitrate' the command returns: wlan0 unknown bit-rate information. Current Bit Rate:78 Mb/s Any ideas? Here's some info (hopefully relevant) on my setup: Xubuntu (12.04.3) 64bit (kernel 3.2.0-55.85-generic) using Network Manager. My Router is from Virgin Media, the VMDG480. lshw -C network : *-network description: Wireless interface physical id: 1 bus info: usb@1:4 logical name: wlan0 serial: 74:ea:3a:8f:16:b6 capabilities: ethernet physical wireless configuration: broadcast=yes driver=ath9k_htc driverversion=3.2.0-55 firmware=1.3 ip=192.168.0.9 link=yes multicast=yes wireless=IEEE 802.11bgn lsusb -v: Bus 001 Device 003: ID 0cf3:7015 Atheros Communications, Inc. TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287] Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 255 Vendor Specific Subclass bDeviceProtocol 255 Vendor Specific Protocol bMaxPacketSize0 64 idVendor 0x0cf3 Atheros Communications, Inc. idProduct 0x7015 TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287] bcdDevice 2.02 iManufacturer 16 ATHEROS iProduct 32 UB95 iSerial 48 12345 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 60 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 500mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 6 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x83 EP 3 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x04 EP 4 OUT bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x05 EP 5 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x06 EP 6 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 255 Vendor Specific Subclass bDeviceProtocol 255 Vendor Specific Protocol bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) iwlist wlan0 scanning: wlan0 Scan completed : Cell 01 - Address: C4:3D:C7:3A:1F:5D Channel:1 Frequency:2.412 GHz (Channel 1) Quality=37/70 Signal level=-73 dBm Encryption key:on ESSID:"my essid" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s Mode:Master Extra:tsf=00000070cca77186 Extra: Last beacon: 5588ms ago IE: Unknown: 0007756E69636F726E IE: Unknown: 010882848B962430486C IE: Unknown: 030101 IE: Unknown: 2A0100 IE: Unknown: 2F0100 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: 32040C121860 IE: Unknown: 2D1AFC181BFFFF000000000000000000000000000000000000000000 IE: Unknown: 3D1601080400000000000000000000000000000000000000 IE: Unknown: DD7E0050F204104A0001101044000102103B00010310470010F99C335D7BAC57FB00137DFA79600220102100074E657467656172102300074E6574676561721024000631323334353610420007303030303030311054000800060050F20400011011000743473331303144100800022008103C0001011049000600372A000120 IE: Unknown: DD090010180203F02C0000 IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00 iwconfig: lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:"my essid" Mode:Managed Frequency:2.412 GHz Access Point: C4:3D:C7:3A:1F:5D Bit Rate=78 Mb/s Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=36/70 Signal level=-74 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0,

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• What's New in Oracle VM VirtualBox 4.2?

  - by Fat Bloke

  A year is a long time in the IT industry. Since the last VirtualBox feature release, which was a little over a year ago, we've seen: new releases of cool new operating systems, such as Windows 8, ChromeOS, and Mountain Lion; we've seen a myriad of new Linux releases from big Enterprise class distributions like Oracle 6.3, to accessible desktop distros like Ubuntu 12.04 and Fedora 17; and we've also seen the spec of a typical PC or laptop double in power. All of these events have influenced our new VirtualBox version which we're releasing today. Here's how... Powerful hosts  One of the trends we've seen is that as the average host platform becomes more powerful, our users are consistently running more and more vm's. Some of our users have large libraries of vm's of various vintages, whilst others have groups of vm's that are run together as an assembly of the various tiers in a multi-tiered software solution, for example, a database tier, middleware tier, and front-ends.  So we're pleased to unveil a more powerful VirtualBox Manager to address the needs of these users: VM Groups Groups allow you to organize your VM library in a sensible way, e.g.  by platform type, by project, by version, by whatever. To create groups you can drag one VM onto another or select one or more VM's and choose Machine...Group from the menu bar. You can expand and collapse groups to save screen real estate, and you can Enter and Leave a group (think iPad navigation here) by using the right and left arrow keys when groups are selected. But groups are more than passive folders, because you can now also perform operations on groups, rather than all the individual VMs. So if you have a multi-tiered solution you can start the whole stack up with just one click. Autostart Many VirtualBox users run dedicated services in their VMs, for example, running a Wiki. With these types of VM workloads, you really want the VM start up when the host machine boots up. So with 4.2 we've introduced a cross-platform Auto-start mechanism to allow you to treat VMs as host services. Headless VM Launching With VM's such as web servers, wikis, and other types of server-class workloads, the Console of the VM is pretty much redundant. For some time now VirtualBox has offered a separate launch mechanism for these VM's, namely the command-line interface commands VBoxHeadless or VBoxManage startvm ... --type headless commands. But with 4.2 we also allow you launch headless VMs from the Manager. Simply hold down Shift when launching the VM from the Manager.  It's that easy. But how do you stop a headless VM? Well, with 4.2 we allow you to Close the VM from the Manager. (BTW best to use the ACPI Shutdown method which allows the guest VM to close down gracefully.) Easy VM Creation For our expert users, the  New VM Wizard was a little tiresome, so now there's a faster 2-click VM creation mode. Just Hide the description when creating a new VM. Powerful VMs  As the hosts have become more powerful, so are the guests that are running inside them. Here are some of the 4.2 features to accommodate them: Virtual Network Interface Cards  With 4.2, it's now possible to create VMs with up to 36 NICs, when using the ICH9 chipset emulation. But with great power comes great responsibility (didn't Obi-Wan say something similar?), and so we have also introduced bandwidth limiting to prevent a rogue VM stealing the whole pipe. VLAN tagging Some of our users leverage VLANs extensively so we've enhanced the E1000 NICs to support this.  Processor Performance If you are running a CPU which supports Nested Paging (aka EPT in the Intel world) such as most of the Core i5 and i7 CPUs, or are running an AMD Bulldozer or later, you should see some performance improvements from our work with these processors. And while we're talking Processors, we've added support for some of the more modern VIA CPUs too. Powerful Automation Because VirtualBox runs atop a fully blown operating system, it makes sense to leverage the capabilities of the host to run scripts that can drive the guest VMs. Guest Automation was introduced in a prior release but with 4.2 we've revamped the APIs to allow a richer and more powerful set of operations to be executed by the guest. Check out the IGuest APIs in the VirtualBox Programming Guide and Reference (SDK). Powerful Platforms  All the hardcore engineering that has gone into 4.2 has been done for a purpose and that is to deliver a fast and powerful engine that can run almost any x86 OS because of the integrity of the virtualization. So we're pleased to add support for these platforms: Mac OS X "Mountain Lion"  Windows 8 Windows Server 2012 Ubuntu 12.04 (“Precise Pangolin”) Fedora 17 Oracle Linux 6.3  Here's the proof: We don't have time to go into the myriad of smaller improvements such as support for burning audio CDs from a guest, bi-directional clipboard control,  drag-and-drop of files into Linux guests, etc. so we'll leave that as an exercise for the user as soon as you've downloaded from the Oracle or community site and taken a peek at the User Guide. So all in all, a pretty solid release, one that we hope you'll enjoy discovering. - FB 

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• The architecture and technologies to use for a secure, fast, reliable and easily scalable web application

  - by DSoul

  ^ For actual questions, skip to the lists down below I understand, that his is a vague topic, but please, before you turn the other way and disregard me, hear me out. I am currently doing research for a web application(I don't know if application is the correct word for it, but I will proceed w/ that for now), that one day might need to be everything mentioned in the title. I am bound by nothing. That means that every language, OS and framework is acceptable, but only if it proves it's usefulness. And if you are going to say, that scalability and speed depend on the code I write for this application, then I agree, but I am just trying to find something, that wouldn't stand in my way later on. I have done quite a bit reading on this subject, but I still don't have a clear picture, to what suits my needs, so I come to you, StackOverflow, to give me directions. I know you all must be wondering what I'm building, but I assure you, that it doesn't matter. I have heard of 12 factor app though, if you have any similar guidelines or what is, to suggest the please, go ahead. For the sake of keeping your answers as open as possible, I'm not gonna provide you my experience regarding anything written in this question. ^ Skippers, start here First off - the weights of the requirements are probably something like that (on a scale of 10): Security - 10 Speed - 5 Reliability (concurrency) - 7.5 Scalability - 10 Speed and concurrency are not a top priority, in the sense, that the program can be CPU intensive, and therefore slow, and only accept a not-that-high number of concurrent users, but both of these factors must be improvable by scaling the system Anyway, here are my questions: How many layers should the application have, so it would be future-proof and could best fulfill the aforementioned requirements? For now, what I have in mind is the most common version: Completely separated front end, that might be a web page or an MMI application or even both. Some middle-ware handling communication between the front and the back end. This is probably a server that communicates w/ the front end via HTTP. How the communication w/ the back end should be handled is probably dependent on the back end. The back end. Something that handles data through resources like DB and etc. and does various computations w/ the data. This, as the highest priority part of the software, must be easily spread to multiple computers later on and have no known security holes. I think ideally the middle-ware should send a request to a queue from where one of the back end processes takes this request, chops it up to smaller parts and buts these parts of the request back onto the same queue as the initial request, after what these parts will be then handled by other back end processes. Something *map-reduce*y, so to say. What frameworks, languages and etc. should these layers use? The technologies used here are not that important at this moment, you can ignore this part for now I've been pointed to node.js for this part. Do you guys know any better alternatives, or have any reasons why I should (not) use node.js for this particular job. I actually have no good idea, what to use for this job, there are too many options out there, so please direct me. This part (and the 2. one also, I think) depend a lot on the OS, so suggest any OSs alongside w/ the technologies/frameworks. Initially, all computers (or 1 for starters) hosting the back end are going to be virtual machines. Please do give suggestions to any part of the question, that you feel you have comprehensive knowledge and/or experience of. And also, point out if you feel that any part of the current set-up means an instant (or even distant) failure or if I missed a very important aspect to consider. I'm not looking for a definitive answer for how to achieve my goals, because there certainly isn't one, for I haven't provided you w/ all the required information. I'm just looking for recommendations and directions on what to look into. Also, bare in mind, that this isn't something that I have to get done quickly, to sell and let it be re-written by the new owner (which, I've been told for multiple times, is what I should aim for). I have all the time in the world and I really just want to learn doing something really high-end. Also, excuse me if my language isn't the best, I'm not a native. Anyway. Thanks in advance to anyone, who takes the time to help me out here. PS. When I do seem to come up w/ a good architecture/design for this project, I will certainly make it an open project and keep you guys up to date w/ it's development. As in what you could have told me earlier and etc. For obvious reasons the very same question got closed on SO, but could you guys still help me?.

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• Notes from AT&T ARO Session at Oredev 2013

  - by Geertjan

  The mobile internet is 12 times bigger than internet was 12 years ago. Explosive growth, faster networks, and more powerful devices. 85% of users prefer mobile apps, while 56% have problems. Almost 60% want less than 2 second mobile app startup. App with poor mobile experience results in not buying stuff, going to competitor, not liking your company. Battery life. Bad mobile app is worse than no app at all because it turns people away from brand, etc. Apps didn't exist 10 years ago, 72 billion dollars a year in 2013, 151 billion in 2017.Testing performance. Mobile is different than regular app. Need to fix issues before customers discover them. ARO is free and open source AT&T tool for identifying mobile app performance problems. Mobile data is different -- radio resource control state machine. Radio resource control -- radio from idle to continuous reception -- drains battery, sends data, packets coming through, after packets come through radio is still on which is tail time, after 10 seconds of no data coming through radio goes off. For example, YouTube, e.g., 10 to 15 seconds after every connection, can be huge drain on battery, app traffic triggers RRC state. Goal. Balance fast network connectivity against battery usage. ARO is free and open source and test any platform and won awards. How do I test my app? pcap or tcdump network. Native collector: Android and iOS. Android rooted device is needed. Test app on phone, background data, idle for ads and analytics. Graded against 25 best practices. See all the processes, all network traffic mapped to processes, stats about trace, can look just at your app, exlude Facebook, etc. Many tests conducted, e.g., file download, HTML (wrapped applications, e.g., cordova). Best Practices. Make stuff smaller. GZIP, smaller files, download faster, best for files larger than 800 bytes, minification -- remove tabs and commenting -- browser doesn't need that, just give processor what it needs remove wheat from chaff. Images -- make images smaller, 1024x1024 image for a checkmark, swish it, make it 33% smaller, ARO records the screen, probably could be 9 times smaller. Download less stuff. 17% of HTTP content on mobile is duplicate data because of caching, reloading from cache is 75% to 99% faster than downloading again, 75% possible savings which means app will start up faster because using cache -- everyone wants app starting up 2 seconds. Make fewer HTTP requests. Inline and combine CSS and JS when possible reduces the number of requests, spread images used often. Fewer connections. Faster and use less battery, for example, download an image every 60 secs, download an add every 60 seconds, send analytics every 60 seconds -- instead of that, use transaction manager, download everything at once, reduce amount of time connected to network by 40% also -- 80% of applications do NOT close connections when they are finished, e.g., download picture, 10 seconds later the radio turns off, if you do not explicitly close, eventually server closes, 38% more tail time, 40% less energy if you close connection right away, background data traffic is 27% of data and 55% of network time, this kills the battery. Look at redirection. Adds 200 to 600 ms on each connection, waterfall diagram to all the requests -- e.g., xyz.com redirect to www.xyz.com redirect to xyz.mobi to www.xyz.com, waterfall visualization of packets, minimize redirects but redirects are fine. HTML best practices. Order matters and hiding code (JS downloading blocks rendering, always do CSS before JS or JS asynchronously, CSS 'display:none' hides images from user but the browser downloads them which adds latency to application. Some apps turn on GPS for no reason. Tell network when down, but maybe some other app is using the radio at the same time. It's all about knowing best practices: everyone wins with ARO (carriers, e.g., AT&T, developers, customers). Faster apps, better battery usage, network traffic better, better app reviews, happier customers. MBTA app, referenced as an example.ARO is free, open source, can test all platforms.

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• UIScrollView image/photo viewer with paging enabled and zooming

  - by Mike Weller

  OK, I think it's time to make an official place on the internet for this problem: How to make a UIScrollView photoviewer with paging and zooming. Welcome my fellow UIScrollView hackers. I have a UIScrollView with paging enabled, and I'm displaying UIImageViews like the built-in photos app. (Does this sound familiar yet?) I found the following project on github: http://wiki.github.com/andreyvit/ScrollingMadness Which shows how to implement zooming in a scroll view while paging is enabled. If anyone else tries this out, I actually had to remove the UIScrollView subclass and use the native class otherwise it doesn't work. I think it's because of changes in the 3.0 SDK relating to how the scroll view intercepts touch events. So the the idea is to remove all the other views when you start zooming, and move the current view to (0, 0) in the scrollview, updating the contentsize etc. Then when you zoom back to 1.0f it adds the other views back and puts things all back in order. Anyway, that project works perfectly in the simulator, but on the device there is some nasty movement of the view you are resizing, which looks like it's caused by the fact we are changing the contentsize/offset etc. for the view being resized. You have to do this view moving otherwise you can pan left through the whitespace left by the other views. I found one interesting note in the "Known Issues" of the 3.0 SDK release notes: UIScrollView: After zooming, content inset is ignored and content is left in the wrong position. This kind of sounds like what is happening here. After zooming in, the view will shift offscreen because you have changed the offset etc. I've spent hours on this already and I'm slowing coming to the sad realization that this just isn't going to work. Three20's photo viewer is out of the question: it's too heavy weight and there is too much unnecessary UI and other behaviour. The built in Photo app seems to do some magic. If you zoom in on an image and pan to the far edges, the current photo moves independently of the photo next to it which isn't what you get when trying this with a standard UIScrollView. I've seen discussion about nesting the UIScrollView's but I really don't want to go there. Has anybody managed this with the standard UIScrollView (and works in the 2.2 and 3.0 SDK)? I don't fancy rolling my own zoom + bounce + pan + paging code.

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• Stop lazy loading or skip loading a property in NHibernate? Proxy cannot be serialized through WCF

  - by HelloSam

  Consider I have a parent, child relationship class and mapping. I am using NHibernate to read the object from the database, and intended to use WCF to send the object across the wire. Goal For reading the parent object, I want to selectively, at different execution path, decide when I would want to load the child object. Because I don't want to read more than what I needed. Those partially loaded object must be able to sent through WCF. When I mean I don't load it, neither side will access such property. Problem When such partially loaded object is being sent through WCF, as those property is marked as [DataContract], it cannot be serialized as the property is lazy load proxy instead of real known type. What I want to archive, or solution that I can think of lazy=false or lazy=true doesn't work. Former will eagerly fetch all the relationships, latter will create a proxy. But I want nothing instead - a null would be the best. I don't need lazy load. I hope to get a null for those references that I don't want to fetch. A null, but not just a proxy. This will makes WCF happy, and waste less time to have a lazy-load proxy constructed. Like could I have a null proxy factory? -OR- Or making WCF ignoring those property that's a proxy instead of real. I tried the IDataContractSurrogate solution, but only parent is passed to GetObjectToSerialize, I never observe an proxy being passed through GetObjectToSerialize, leaving no chance to un-proxy it. Edit After reading the comments, more surfing on the Internet... It seems to me that DTO would shift major part of the computation to the server side. But for the project I am working on, 50% of time the client is "smarter" than the server and the server is more like a data store with validation and verification. Though I agree the server is not exactly dumb - I have to decide when to fetch the extra references already, and DTO will make this very explicit. Maybe I should just take the pain. I didn't know http://automapper.codeplex.com/ before, this motivates me a little more to take the pain. On the other hand, I found http://trentacular.com/2009/08/how-to-use-nhibernate-lazy-initializing-proxies-with-web-services-or-wcf/, which seems to be working with IDataContractSurrogate.GetObjectToSerialize.

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• How do you Send More that 20 Parameters to a Stored Procedure Using ODP.Net?

  - by discwiz

  Switching from Microsofts Oracle Driver to ODP.NET version 10.2.0.100. After changing the data types to OracleDBTypes in a procedure, that worked perficetly using System.Data.OracleClient, the procedure fails if we try and pass in more that 20 parameters. The error returned is: ORA-06550: line 1, column 7: PLS-00306: wrong number or types of arguments in call to 'ADD_TARP_EVENT' ORA-06550: line 1, column 7: PL/SQL: Statement ignorede If we reduce the number of parameters to less than 20 it works. Is this a known issue? Thanks, Dave Here the code for creating the parameters: Shared Function CreateTarpEventCommand(ByVal aTarpEvent As TARPEventType) As OracleCommand Dim cmd As New OracleCommand With aTarpEvent cmd.Parameters.Add(New OracleParameter("I_facID_C", OracleDbType.Char)).Value = .FacilityShortName cmd.Parameters.Add(New OracleParameter("I_facName_VC", OracleDbType.Varchar2)).Value = .FacilityLongName cmd.Parameters.Add(New OracleParameter("I_client_VC", OracleDbType.Varchar2)).Value = .ComputerNameTarpIsRunningOn cmd.Parameters.Add(New OracleParameter("I_TARP_Version_VC", OracleDbType.Varchar2)).Value = .TarpVersionNumber cmd.Parameters.Add(New OracleParameter("I_NAS_Type_VC", OracleDbType.Varchar2)).Value = .FacilityNASSystemType cmd.Parameters.Add(New OracleParameter("I_Aircraft1_Callsign_VC", OracleDbType.Varchar2)).Value = .Aircraft1Callsign If .Aircraft1Type Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Aircraft1_Type_VC", OracleDbType.Varchar2)).Value = .Aircraft1Type End If If .Aircraft1Category Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Aircraft1_Cat_VC", OracleDbType.Varchar2)).Value = .Aircraft1Category End If cmd.Parameters.Add(New OracleParameter("I_Aircraft2_Callsign_VC", OracleDbType.Varchar2)).Value = .Aircraft2Callsign If .Aircraft2Type Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Aircraft2_Type_VC", OracleDbType.Varchar2)).Value = .Aircraft2Type End If If .Aircraft2Category Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Aircraft2_Cat_VC", OracleDbType.Varchar2)).Value = .Aircraft2Category End If If .SensorShortName Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Sensor_Name_VC", OracleDbType.Varchar2)).Value = .SensorShortName End If If .TarpConfigurationName Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_TARP_Config_Name_VC", OracleDbType.Varchar2)).Value = .TarpConfigurationName End If If .EntryCreatorID Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Create_VC", OracleDbType.Varchar2)).Value = .EntryCreatorID End If If .LogAction Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Log_Action_VC", OracleDbType.Varchar2)).Value = .LogAction End If cmd.Parameters.Add(New OracleParameter("I_TARP_Mode_VC", OracleDbType.Varchar2)).Value = .TarpOperatingMode cmd.Parameters.Add(New OracleParameter("I_Min_Loss_N", OracleDbType.Decimal)).Value = .ClosestMeasureOfLoSS If .MapName Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_MAP_NAME_VC", OracleDbType.Varchar2)).Value = .MapName End If If .TarpConfigurationFileHash Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_CONFIG_HASH_VC", OracleDbType.Varchar2)).Value = .TarpConfigurationFileHash End If Dim aDate As OracleDate = CType(.LossEventsMessages(0).LossEventTime, System.DateTime) cmd.Parameters.Add(New OracleParameter("I_FIRST_LOSS_EVENT_DATE", OracleDbType.Date)).Value = aDate cmd.Parameters.Add(New OracleParameter("I_FIRST_LOSS_EVENT_MS_N", OracleDbType.Int32)).Value = .LossEventsMessages(0).LossEventMilliSeconds If .ZippedMapFiles Is Nothing Then cmd.Parameters.Add(New OracleParameter("I_Map_File_BL", OracleDbType.Blob)).Value = .ZippedMapFiles End If cmd.Parameters.Add(New OracleParameter("I_TARP_Package_BL", OracleDbType.Blob)).Value = .ZippedTarpPackageWithoutMaps cmd.Parameters.Add(New OracleParameter("rs_RESULTS", OracleDbType.RefCursor)).Direction = ParameterDirection.Output End With Return cmd End Function And here is the code for executing the procedure: Dim workingDataSet As New DataSet Dim oracleConnection As New OracleConnection Dim cmd As New OracleCommand Dim oracleDataAdapter As New OracleDataAdapter Try Using oracleConnection oracleConnection.ConnectionString = System.Configuration.ConfigurationManager.AppSettings("MasterConnectionODT") cmd = HelperDB.CreateTarpEventCommand(TarpEvent) cmd.Connection = oracleConnection cmd.CommandText = "LOADER.ADD_TARP_EVENT" cmd.CommandType = CommandType.StoredProcedure Using oracleConnection oracleConnection.Open() Dim aTransation As OracleTransaction = oracleConnection.BeginTransaction(IsolationLevel.ReadCommitted) Try Using oracleDataAdapter oracleDataAdapter = New OracleDataAdapter(cmd) oracleDataAdapter.TableMappings.Add("Results", "rs_Max") oracleDataAdapter.Fill(workingDataSet) ....

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• Python performance: iteration and operations on nested lists

  - by J.J.

  Problem Hey folks. I'm looking for some advice on python performance. Some background on my problem: Given: A mesh of nodes of size (x,y) each with a value (0...255) starting at 0 A list of N input coordinates each at a specified location within the range (0...x, 0...y) Increment the value of the node at the input coordinate and the node's neighbors within range Z up to a maximum of 255. Neighbors beyond the mesh edge are ignored. (No wrapping) BASE CASE: A mesh of size 1024x1024 nodes, with 400 input coordinates and a range Z of 75 nodes. Processing should be O(x*y*Z*N). I expect x, y and Z to remain roughly around the values in the base case, but the number of input coordinates N could increase up to 100,000. My goal is to minimize processing time. Current results I have 2 current implementations: f1, f2 Running speed on my 2.26 GHz Intel Core 2 Duo with Python 2.6.1: f1: 2.9s f2: 1.8s f1 is the initial naive implementation: three nested for loops. f2 is replaces the inner for loop with a list comprehension. Code is included below for your perusal. Question How can I further reduce the processing time? I'd prefer sub-1.0s for the test parameters. Please, keep the recommendations to native Python. I know I can move to a third-party package such as numpy, but I'm trying to avoid any third party packages. Also, I've generated random input coordinates, and simplified the definition of the node value updates to keep our discussion simple. The specifics have to change slightly and are outside the scope of my question. thanks much! f1 is the initial naive implementation: three nested for loops. 2.9s def f1(x,y,n,z): rows = [] for i in range(x): rows.append([0 for i in xrange(y)]) for i in range(n): inputX, inputY = (int(x*random.random()), int(y*random.random())) topleft = (inputX - z, inputY - z) for i in xrange(max(0, topleft[0]), min(topleft[0]+(z*2), x)): for j in xrange(max(0, topleft[1]), min(topleft[1]+(z*2), y)): if rows[i][j] <= 255: rows[i][j] += 1 f2 is replaces the inner for loop with a list comprehension. 1.8s def f2(x,y,n,z): rows = [] for i in range(x): rows.append([0 for i in xrange(y)]) for i in range(n): inputX, inputY = (int(x*random.random()), int(y*random.random())) topleft = (inputX - z, inputY - z) for i in xrange(max(0, topleft[0]), min(topleft[0]+(z*2), x)): l = max(0, topleft[1]) r = min(topleft[1]+(z*2), y) rows[i][l:r] = [j+1 for j in rows[i][l:r] if j < 255]

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• How to optimize my PageRank calculation?

  - by asmaier

  In the book Programming Collective Intelligence I found the following function to compute the PageRank: def calculatepagerank(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() for i in range(iterations): print "Iteration %d" % i for (urlid,) in self.con.execute("select rowid from urllist"): pr=0.15 # Loop through all the pages that link to this one for (linker,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): # Get the PageRank of the linker linkingpr=self.con.execute("select score from pagerank where urlid=%d" % linker).fetchone()[0] # Get the total number of links from the linker linkingcount=self.con.execute("select count(*) from link where fromid=%d" % linker).fetchone()[0] pr+=0.85*(linkingpr/linkingcount) self.con.execute("update pagerank set score=%f where urlid=%d" % (pr,urlid)) self.dbcommit() However, this function is very slow, because of all the SQL queries in every iteration >>> import cProfile >>> cProfile.run("crawler.calculatepagerank()") 2262510 function calls in 136.006 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.000 0.000 136.006 136.006 <string>:1(<module>) 1 20.826 20.826 136.006 136.006 searchengine.py:179(calculatepagerank) 21 0.000 0.000 0.528 0.025 searchengine.py:27(dbcommit) 21 0.528 0.025 0.528 0.025 {method 'commit' of 'sqlite3.Connecti 1 0.000 0.000 0.000 0.000 {method 'disable' of '_lsprof.Profiler 1339864 112.602 0.000 112.602 0.000 {method 'execute' of 'sqlite3.Connec 922600 2.050 0.000 2.050 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} So I optimized the function and came up with this: def calculatepagerank2(self,iterations=20): # clear out the current PageRank tables self.con.execute("drop table if exists pagerank") self.con.execute("create table pagerank(urlid primary key,score)") self.con.execute("create index prankidx on pagerank(urlid)") # initialize every url with a PageRank of 1.0 self.con.execute("insert into pagerank select rowid,1.0 from urllist") self.dbcommit() inlinks={} numoutlinks={} pagerank={} for (urlid,) in self.con.execute("select rowid from urllist"): inlinks[urlid]=[] numoutlinks[urlid]=0 # Initialize pagerank vector with 1.0 pagerank[urlid]=1.0 # Loop through all the pages that link to this one for (inlink,) in self.con.execute("select distinct fromid from link where toid=%d" % urlid): inlinks[urlid].append(inlink) # get number of outgoing links from a page numoutlinks[urlid]=self.con.execute("select count(*) from link where fromid=%d" % urlid).fetchone()[0] for i in range(iterations): print "Iteration %d" % i for urlid in pagerank: pr=0.15 for link in inlinks[urlid]: linkpr=pagerank[link] linkcount=numoutlinks[link] pr+=0.85*(linkpr/linkcount) pagerank[urlid]=pr for urlid in pagerank: self.con.execute("update pagerank set score=%f where urlid=%d" % (pagerank[urlid],urlid)) self.dbcommit() This function is 20 times faster (but uses a lot more memory for all the temporary dictionaries) because it avoids the unnecessary SQL queries in every iteration: >>> cProfile.run("crawler.calculatepagerank2()") 64802 function calls in 6.950 CPU seconds Ordered by: standard name ncalls tottime percall cumtime percall filename:lineno(function) 1 0.004 0.004 6.950 6.950 <string>:1(<module>) 1 1.004 1.004 6.946 6.946 searchengine.py:207(calculatepagerank2 2 0.000 0.000 0.104 0.052 searchengine.py:27(dbcommit) 23065 0.012 0.000 0.012 0.000 {meth 'append' of 'list' objects} 2 0.104 0.052 0.104 0.052 {meth 'commit' of 'sqlite3.Connection 1 0.000 0.000 0.000 0.000 {meth 'disable' of '_lsprof.Profiler' 31298 5.809 0.000 5.809 0.000 {meth 'execute' of 'sqlite3.Connectio 10431 0.018 0.000 0.018 0.000 {method 'fetchone' of 'sqlite3.Cursor' 1 0.000 0.000 0.000 0.000 {range} But is it possible to further reduce the number of SQL queries to speed up the function even more?

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• IE8 v8 not changing class for a DOM element despite JS function changing the element attribute

  - by Alfabravo

  I have an on-screen keyboard in order to provide a safer input for passwords. The keyboard itself is placed like this: <div class="teclado_grafico" id="teclado_grafico"> <a class="tecla_teclado" onmousedown="teclaAction( this, 'caja_selector'); return false" style="top: 0px; left: 0px;">Q</a> <a class="tecla_teclado" onmousedown="teclaAction( this, 'caja_selector'); return false" style="top: 0px; left: 28px;">W</a> . . . </div> And it has a "Shift button" which fires a JS function with this (I've already tried all that, indeed): if (obj.innerHTML == "Mayus.") { try { MAYUSCULA_ACTIVADO = !MAYUSCULA_ACTIVADO; var tgrafico = document.getElementById("teclado_grafico"); if(MAYUSCULA_ACTIVADO) { // tgrafico.className = "teclado_grafico mayuscula"; // $("#teclado_grafico").removeClass('minuscula').addClass('mayuscula'); // $("#teclado_grafico").attr('class', 'teclado_grafico mayuscula'); // $("#teclado_grafico").attr('className', 'teclado_grafico mayuscula'); tgrafico.setAttribute('className', "teclado_grafico mayuscula") || tgrafico.setAttribute('class', "teclado_grafico mayuscula"); } else { // tgrafico.className = "teclado_grafico minuscula"; // $("#teclado_grafico").removeClass('mayuscula').addClass('minuscula'); // $("#teclado_grafico").attr('class', 'teclado_grafico minuscula'); // $("#teclado_grafico").attr('className', 'teclado_grafico minuscula'); tgrafico.setAttribute('className', "teclado_grafico minuscula") || tgrafico.setAttribute('class', "teclado_grafico minuscula"); } } catch (_E) { //void } return; } The associated CSS is like this: .mayuscula a.tecla_teclado{ text-transform: uppercase; } .minuscula a.tecla_teclado{ text-transform: lowercase; } It works on every single browser I've tried. IE 6, 7; Opera 10; GChrome; FF 3, 3.5 and 3.6; Safari 4,... but in IE8 v8 (strict mode) the class is not changed! I mean, debuggin' with the IE8 tools allows one to see that the attribute className is there and it changes... but the user does not see the letters changing from uppercase to lowercase, to uppercase again. I just don't know how to handle this... I had complains about the client using IE6... now they updated their stuff and this shows up. Any help will be reaaaaly helpful!

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• .NET RegEx "Memory Leak" investigation

  - by Kevin Pullin

  I recently looked into some .NET "memory leaks" (i.e. unexpected, lingering GC rooted objects) in a WinForms app. After loading and then closing a huge report, the memory usage did not drop as expected even after a couple of gen2 collections. Assuming that the reporting control was being kept alive by a stray event handler I cracked open WinDbg to see what was happening... Using WinDbg, the !dumpheap -stat command reported a large amount of memory was consumed by string instances. Further refining this down with the !dumpheap -type System.String command I found the culprit, a 90MB string used for the report, at address 03be7930. The last step was to invoke !gcroot 03be7930 to see which object(s) were keeping it alive. My expectations were incorrect - it was not an unhooked event handler hanging onto the reporting control (and report string), but instead it was held on by a System.Text.RegularExpressions.RegexInterpreter instance, which itself is a descendant of a System.Text.RegularExpressions.CachedCodeEntry. Now, the caching of Regexs is (somewhat) common knowledge as this helps to reduce the overhead of having to recompile the Regex each time it is used. But what then does this have to do with keeping my string alive? Based on analysis using Reflector, it turns out that the input string is stored in the RegexInterpreter whenever a Regex method is called. The RegexInterpreter holds onto this string reference until a new string is fed into it by a subsequent Regex method invocation. I'd expect similar behaviour by hanging onto Regex.Match instances and perhaps others. The chain is something like this: Regex.Split, Regex.Match, Regex.Replace, etc Regex.Run RegexScanner.Scan (RegexScanner is the base class, RegexInterpreter is the subclass described above). The offending Regex is only used for reporting, rarely used, and therefore unlikely to be used again to clear out the existing report string. And even if the Regex was used at a later point, it would probably be processing another large report. This is a relatively significant problem and just plain feels dirty. All that said, I found a few options on how to resolve, or at least work around, this scenario. I'll let the community respond first and if no takers come forward I will fill in any gaps in a day or two.

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• cannot evaluate expression because a native frame is on top of the call stack and system.accessviolationexception

  - by Joseph

  I have this code using c#. public partial class MainForm : Form { private CvCapture VideoCapture; private IplImage frame; private IplImage imgMain; public MainForm() { InitializeComponent(); } private void btnVideo_Click(object sender, EventArgs e) { double vidWidth, vidHeight; try { VideoCapture = highgui.CvCreateCameraCapture(0); } catch (Exception except) { MessageBox.Show(except.Message); } if (btnVideo.Text.CompareTo("Start Video") == 0) { if (VideoCapture.ptr == IntPtr.Zero) { MessageBox.Show("badtrip ah!!!"); return; } btnVideo.Text = "Stop Video"; highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH, 640); highgui.CvSetCaptureProperty(ref VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT, 480); highgui.CvQueryFrame(ref VideoCapture); vidWidth = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_WIDTH); vidHeight = highgui.cvGetCaptureProperty(VideoCapture, highgui.CV_CAP_PROP_FRAME_HEIGHT); picBoxMain.Width = (int)vidWidth; picBoxMain.Height = (int)vidHeight; timerGrab.Enabled = true; timerGrab.Interval = 42; timerGrab.Start(); } else { btnVideo.Text = "Start Video"; timerGrab.Enabled = false; if (VideoCapture.ptr == IntPtr.Zero) { highgui.CvReleaseCapture(ref VideoCapture); VideoCapture.ptr = IntPtr.Zero; } } } private void timerGrab_Tick(object sender, EventArgs e) { try { frame = highgui.CvQueryFrame(ref VideoCapture); if (frame.ptr == IntPtr.Zero) { timerGrab.Stop(); MessageBox.Show("??"); return; } imgMain = cxcore.CvCreateImage(cxcore.CvGetSize(ref frame), 8, 3); picBoxMain.Image = highgui.ToBitmap(imgMain, false); cxcore.CvReleaseImage(ref imgMain); //cxcore.CvReleaseImage(ref frame); } catch (Exception excpt) { MessageBox.Show(excpt.Message); } } } The problem is after i break all and step through the debugger the program stops at a certain code. the code where it stops is here: frame = highgui.CvQueryFrame(ref VideoCapture); the error is that it says that cannot evaluate expression because a native frame is on top of the call stack. and then when i try to shift+F11 it. there is another error saying that system.accessviolationexception. the stack trace says that: at System.Runtime.InteropServices.Marshal.CopyToManaged(IntPtr source, Object destination, Int32 startIndex, Int32 length) at CxCore.IplImage.get_ImageDataDb()

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• Building the WAR with m2eclipse in combination with WTP (handling webResources)

  - by waxwing

  I have a situation where I have a web application that is built using maven (i.e., maven-war-plugin). For each code modification, we have had to manually launch maven and restart the application server. Now, to reduce build cycle overhead, I want to use WTP to publish the webapp. Now, we have resource processing with Maven, and there are some additional Maven tasks defined in our POM when building the webapp. Therefore m2eclipse seems like a natural solution. I have gotten far enough that the Maven builder is running these tasks and filtering resources correctly. However, when I choose "Run on Server", the WAR file does not look like it would if I built it in Maven. I am guessing that this is because WTP actually builds the WAR, and not the m2eclipse builder. So even though we have configured the maven-war-plugin in our POM, those settings are not used. Below is a snippet with our maven-war-plugin configuration. What is configured under "webResources" is not picked up, it appears: <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-war-plugin</artifactId> <version>2.1-alpha-2</version> <configuration> <outputDirectory>${project.build.directory}</outputDirectory> <workDirectory>${project.build.directory}/work</workDirectory> <webappDirectory>${project.build.webappDirectory}</webappDirectory> <cacheFile>${project.build.webappDirectory}/webapp-cache.xml</cacheFile> <filteringDeploymentDescriptors>true</filteringDeploymentDescriptors> <nonFilteredFileExtensions> <nonFilteredFileExtension>pdf</nonFilteredFileExtension> <nonFilteredFileExtension>png</nonFilteredFileExtension> <nonFilteredFileExtension>gif</nonFilteredFileExtension> <nonFilteredFileExtension>jsp</nonFilteredFileExtension> </nonFilteredFileExtensions> <webResources> <!-- Add generated WSDL:s and XSD:s for the web service api. --> <resource> <directory>${project.build.directory}/jaxws/wsgen/wsdl</directory> <targetPath>WEB-INF/wsdl</targetPath> <filtering>false</filtering> <includes> <include>**/*</include> </includes> </resource> </webResources> </configuration> Do I need to reconfigure these resources to be handled elsewhere, or is there a better solution?

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• Is this asking too much of a browser?

  - by Matt Ball

  I'm embedding a large array in <script> tags in my HTML, like this (nothing surprising): <script> var largeArray = [/* lots of stuff in here */]; </script> In this particular example, the array has 210,000 elements. That's well below the theoretical maximum of 231 - by 4 orders of magnitude. Here's the fun part: if I save JS source for the array to a file, that file is 44 megabytes (46,573,399 bytes, to be exact). If you want to see for yourself, you can download it from my Dropbox. (All the data in there is canned, so much of it is repeated. This will not be the case in production.) Now, I'm really not concerned about serving that much data. My server gzips its responses, so it really doesn't take all that long to get the data over the wire. However, there is a really nasty tendency for the page, once loaded, to crash the browser. I'm not testing at all in IE (this is an internal tool). My primary targets are Chrome 8 and Firefox 3.6. In Firefox, I can see a reasonably useful error in the console: Error: script stack space quota is exhausted In Chrome, I simply get the sad-tab page: Cut to the chase, already Is this really too much data for our modern, "high-performance" browsers to handle? Is there anything I can do* to gracefully handle this much data? Incidentally, I was able to get this to work (read: not crash the tab) on-and-off in Chrome. I really thought that Chrome, at least, was made of tougher stuff, but apparently I was wrong... Edit 1 @Crayon: I wasn't looking to justify why I'd like to dump this much data into the browser at once. Short version: either I solve this one (admittedly not-that-easy) problem, or I have to solve a whole slew of other problems. I'm opting for the simpler approach for now. @various: right now, I'm not especially looking for ways to actually reduce the number of elements in the array. I know I could implement Ajax paging or what-have-you, but that introduces its own set of problems for me in other regards. @Phrogz: each element looks something like this: {dateTime:new Date(1296176400000), terminalId:'terminal999', 'General___BuildVersion':'10.05a_V110119_Beta', 'SSM___ExtId':26680, 'MD_CDMA_NETLOADER_NO_BCAST___Valid':'false', 'MD_CDMA_NETLOADER_NO_BCAST___PngAttempt':0} @Will: but I have a computer with a 4-core processor, 6 gigabytes of RAM, over half a terabyte of disk space ...and I'm not even asking for the browser to do this quickly - I'm just asking for it to work at all! ? *other than the obvious: sending less data to the browser

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• Perl Moose::Util::TypeConstraints bug ? what is this error about the name has invalid chars ?

  - by alex8657

  That has been hours i am tracking a Moose::Util::TypeConstraints exceptions, i don't understand where it gets to check a type and tells me that the name is incorrect. I tracked the error to a reduced example to try to locate the problem, and it just shows me that i do not get it. Did i get to a Moose::Util::TypeConstraints bug ? aoffice:new alex$ perl -c ../codesnippets/typeconstrainterror.pl ../codesnippets/typeconstrainterror.pl syntax OK aoffice:new alex$ perl -d ../codesnippets/typeconstrainterror.pl (...) DB<1> r Something::File::LocalFile=HASH(0x100d1bfa8) contains invalid characters for a type name. Names can contain alphanumeric character, ":", and "." at /opt/local/lib/perl5/vendor_perl/5.10.1/darwin-multi-2level/Moose/Util/TypeConstraints.pm line 508 Moose::Util::TypeConstraints::_create_type_constraint('Something::File::LocalFile=HASH(0x100d1bfa8)', undef, undef, undef, undef) called at /opt/local/lib/perl5/vendor_perl/5.10.1/darwin-multi-2level/Moose/Util/TypeConstraints.pm line 285 Moose::Util::TypeConstraints::type('Something::File::LocalFile=HASH(0x100d1bfa8)') called at ../codesnippets/typeconstrainterror.pl line 7 Something::File::is_slink('Something::File::LocalFile=HASH(0x100d1bfa8)') called at ../codesnippets/typeconstrainterror.pl line 33 Debugged program terminated. Use q to quit or R to restart, use o inhibit_exit to avoid stopping after program termination, h q, h R or h o to get additional info. Below, the code that crashes: package Something::File; use Moose; has 'type' =>(is=>'ro', isa=>'Str', writer=>'_set_type' ); sub is_slink { my $self = shift; return ( $self->type eq 'slink' ); } no Moose; __PACKAGE__->meta->make_immutable; 1; package Something::File::LocalFile; use Moose; use Moose::Util::TypeConstraints; extends 'Something::File'; subtype 'PositiveInt' => as 'Int' => where { $_ >0 } => message { 'Only positive greater than zero integers accepted' }; no Moose; __PACKAGE__->meta->make_immutable; 1; my $a = Something::File::LocalFile->new; # $a->_set_type('slink'); print $a->is_slink ." end\n";

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• How to make efficient code emerge through unit testing

  - by Jean

  Hi, I participate in a TDD Coding Dojo, where we try to practice pure TDD on simple problems. It occured to me however that the code which emerges from the unit tests isn't the most efficient. Now this is fine most of the time, but what if the code usage grows so that efficiency becomes a problem. I love the way the code emerges from unit testing, but is it possible to make the efficiency property emerge through further tests ? Here is a trivial example in ruby: prime factorization. I followed a pure TDD approach making the tests pass one after the other validating my original acceptance test (commented at the bottom). What further steps could I take, if I wanted to make one of the generic prime factorization algorithms emerge ? To reduce the problem domain, let's say I want to get a quadratic sieve implementation ... Now in this precise case I know the "optimal algorithm, but in most cases, the client will simply add a requirement that the feature runs in less than "x" time for a given environment. require 'shoulda' require 'lib/prime' class MathTest < Test::Unit::TestCase context "The math module" do should "have a method to get primes" do assert Math.respond_to? 'primes' end end context "The primes method of Math" do should "return [] for 0" do assert_equal [], Math.primes(0) end should "return [1] for 1 " do assert_equal [1], Math.primes(1) end should "return [1,2] for 2" do assert_equal [1,2], Math.primes(2) end should "return [1,3] for 3" do assert_equal [1,3], Math.primes(3) end should "return [1,2] for 4" do assert_equal [1,2,2], Math.primes(4) end should "return [1,5] for 5" do assert_equal [1,5], Math.primes(5) end should "return [1,2,3] for 6" do assert_equal [1,2,3], Math.primes(6) end should "return [1,3] for 9" do assert_equal [1,3,3], Math.primes(9) end should "return [1,2,5] for 10" do assert_equal [1,2,5], Math.primes(10) end end # context "Functionnal Acceptance test 1" do # context "the prime factors of 14101980 are 1,2,2,3,5,61,3853"do # should "return [1,2,3,5,61,3853] for ${14101980*14101980}" do # assert_equal [1,2,2,3,5,61,3853], Math.primes(14101980*14101980) # end # end # end end and the naive algorithm I created by this approach module Math def self.primes(n) if n==0 return [] else primes=[1] for i in 2..n do if n%i==0 while(n%i==0) primes<<i n=n/i end end end primes end end end

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• Scipy Negative Distance? What?

  - by disappearedng

  I have a input file which are all floating point numbers to 4 decimal place. i.e. 13359 0.0000 0.0000 0.0001 0.0001 0.0002` 0.0003 0.0007 ... (the first is the id). My class uses the loadVectorsFromFile method which multiplies it by 10000 and then int() these numbers. On top of that, I also loop through each vector to ensure that there are no negative values inside. However, when I perform _hclustering, I am continually seeing the error, "Linkage Z contains negative values". I seriously think this is a bug because: I checked my values, the values are no where small enough or big enough to approach the limits of the floating point numbers and the formula that I used to derive the values in the file uses absolute value (my input is DEFINITELY right). Can someone enligten me as to why I am seeing this weird error? What is going on that is causing this negative distance error? ===== def loadVectorsFromFile(self, limit, loc, assertAllPositive=True, inflate=True): """Inflate to prevent "negative" distance, we use 4 decimal points, so *10000 """ vectors = {} self.winfo("Each vector is set to have %d limit in length" % limit) with open( loc ) as inf: for line in filter(None, inf.read().split('\n')): l = line.split('\t') if limit: scores = map(float, l[1:limit+1]) else: scores = map(float, l[1:]) if inflate: vectors[ l[0]] = map( lambda x: int(x*10000), scores) #int might save space else: vectors[ l[0]] = scores if assertAllPositive: #Assert that it has no negative value for dirID, l in vectors.iteritems(): if reduce(operator.or_, map( lambda x: x < 0, l)): self.werror( "Vector %s has negative values!" % dirID) return vectors def main( self, inputDir, outputDir, limit=0, inFname="data.vectors.all", mappingFname='all.id.features.group.intermediate'): """ Loads vector from a file and start clustering INPUT vectors is { featureID: tfidfVector (list), } """ IDFeatureDic = loadIdFeatureGroupDicFromIntermediate( pjoin(self.configDir, mappingFname)) if not os.path.exists(outputDir): os.makedirs(outputDir) vectors = self.loadVectorsFromFile( limit, pjoin( inputDir, inFname)) for threshold in map( lambda x:float(x)/30, range(20,30)): clusters = self._hclustering(threshold, vectors) if clusters: outputLoc = pjoin(outputDir, "threshold.%s.result" % str(threshold)) with open(outputLoc, 'w') as outf: for clusterNo, cluster in clusters.iteritems(): outf.write('%s\n' % str(clusterNo)) for featureID in cluster: feature, group = IDFeatureDic[featureID] outline = "%s\t%s\n" % (feature, group) outf.write(outline.encode('utf-8')) outf.write("\n") else: continue def _hclustering(self, threshold, vectors): """function which you should call to vary the threshold vectors: { featureID: [ tfidf scores, tfidf score, .. ] """ clusters = defaultdict(list) if len(vectors) > 1: try: results = hierarchy.fclusterdata( vectors.values(), threshold, metric='cosine') except ValueError, e: self.werror("_hclustering: %s" % str(e)) return False for i, featureID in enumerate( vectors.keys()):

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• Can Hudson branch promotion get based on project stability?

  - by Wayne

  Hudson CI server displays stability "weather" which is cool. And it allows one project build to kick off based on the successful build of another. However, how can you make that secondary project dependent additionally on the stability of multiple builds of the first project? Specifically, project "stable_deploy" needs to only kick off to promote a version to "stable" if project "integrate" with version 8.3.4.1233 has built and tested successfully at least 8 times--in a row. Until then, it's still in integration mode. IMPORTANT: A significant caveat to this is that a single set of Hudson projects gets used as a "pipeline" to process each new version through to release. So a project may have built successfully 8 times in a rolw but the latest version 8.3.4.1233 may be only the 2 most recent builds. The builds prior to that may be an earlier version. We're open to completely reorganizing this but the pipeline idea seemed to greatly reduce the amount of manually project creation and deletion. Is there a better way to track version release "pipeline"? In particular, we will have multiple versions in this pipeline simultaneously in the future due to fixes or patches to older versions. We don't see how to do that yet, except to create new pipeline projects for each version which is a real hassle. Here's some background details: The TickZoom application has some very complete unit tests some of which simulates real time trading environments. Add to that TickZoom makes elaborate use of parallelization for leveraging multi-core computers. Needless to say, during development of a new version, there can be stability issues during integration testing which get uncovered by running the build and auto tests repeatedly. A version which builds and tests cleanly 8 times in a row without change plus has undergone some real world testing by users can be deemed "stable" and promoted to the stable branch. Our Hudson projects look like this: test - Only for testing a build, zero user visibility. integrate_deploy - Promotes a test project build to integrate branch and makes it available to public for UA testing. integrate - Repeatedly builds the integrate branch to determine if it's stable enough to promote to stable branch. This runs the builds and test hourly throughout every night. stable_deploy - Promotes an integrate project build to the stable branch and makes it public for users who want the latest and greatest. stable - Builds the stable branch once every night. After 2 weeks of successful builds (14 builds) it can go to "release candidate". And so on... it continues with "release candidate" and then "release".

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• Advice on logic circuits and serial communications

  - by Spencer Ruport

  As far as I understand the serial port so far, transferring data is done over pin 3. As shown here: There are two things that make me uncomfortable about this. The first is that it seems to imply that the two connected devices agree on a signal speed and the second is that even if they are configured to run at the same speed you run into possible synchronization issues... right? Such things can be handled I suppose but it seems like there must be a simpler method. What seems like a better approach to me would be to have one of the serial port pins send a pulse that indicates that the next bit is ready to be stored. So if we're hooking these pins up to a shift register we basically have: (some pulse pin)-clk, tx-d Is this a common practice? Is there some reason not to do this? EDIT Mike shouldn't have deleted his answer. This I2C (2 pin serial) approach seems fairly close to what I did. The serial port doesn't have a clock you're right nobugz but that's basically what I've done. See here: private void SendBytes(byte[] data) { int baudRate = 0; int byteToSend = 0; int bitToSend = 0; byte bitmask = 0; byte[] trigger = new byte[1]; trigger[0] = 0; SerialPort p; try { p = new SerialPort(cmbPorts.Text); } catch { return; } if (!int.TryParse(txtBaudRate.Text, out baudRate)) return; if (baudRate < 100) return; p.BaudRate = baudRate; for (int index = 0; index < data.Length * 8; index++) { byteToSend = (int)(index / 8); bitToSend = index - (byteToSend * 8); bitmask = (byte)System.Math.Pow(2, bitToSend); p.Open(); p.Parity = Parity.Space; p.RtsEnable = (byte)(data[byteToSend] & bitmask) > 0; s = p.BaseStream; s.WriteByte(trigger[0]); p.Close(); } } Before anyone tells me how ugly this is or how I'm destroying my transfer speeds my quick answer is I don't care about that. My point is this seems much much simpler than the method you described in your answer nobugz. And it wouldn't be as ugly if the .Net SerialPort class gave me more control over the pin signals. Are there other serial port APIs that do?

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• Release Process Improvements

  - by wallismark

  The process of creating a new build and releasing it to production is a critical step in the SDLC but it is often left as an afterthought and varies greatly from one company to the next. I'm hoping people will share improvements they have made to this process in their organisation so we can all takes steps to 'reduce the pain'. So the question is, specify one painful/time consuming part of your release process and what did you do to improve it? My example: at a previous employer all developers made database changes on one common development database. Then when it came to release time, we used Redgate's SQL Compare to generate a huge script from the differences between the Dev and QA databases. This works reasonably well but the problems with this approach are:- ALL changes in the Dev database are included, some of which may still be 'works in progress'. Sometimes developers made conflicting changes (that were not noticed until the release was in production) It was a time consuming and manual process to create and validate the script (by validate I mean, try to weed out issues like problem 1 and 2). When there were problems with the script (eg the order in which things were run such as creating a record which relies on a foreign key record which is in the script but not yet run) it took time to 'tweak' it so it ran smoothly. It's not an ideal scenario for Continuous Integration. So the solution was:- Enforce a policy of all changes to the database must be scripted. A naming convention was important for ensuring the correct running order of the scripts. Create/Use a tool to run the scripts at release time. Developers had their own copy of the database do develop against (so there was no more 'stepping on each others toes') The next release after we started this process was much faster with fewer problems, indeed the only problems found were due to people 'breaking the rules', eg not creating a script. Once the issues with releasing to QA were fixed, when it came time to release to production it was very smooth. We applied a few other changes (like introducing CI) but this was the most significant, overall we reduced release time from around 3 hours down to a max of 10-15 minutes.

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• Java Hardware Acceleration

  - by Freezerburn

  I have been spending some time looking into the hardware acceleration features of Java, and I am still a bit confused as none of the sites that I found online directly and clearly answered some of the questions I have. So here are the questions I have for hardware acceleration in Java: 1) In Eclipse version 3.6.0, with the most recent Java update for Mac OS X (1.6u10 I think), is hardware acceleration enabled by default? I read somewhere that someCanvas.getGraphicsConfiguration().getBufferCapabilities().isPageFlipping() is supposed to give an indication of whether or not hardware acceleration is enabled, and my program reports back true when that is run on my main Canvas instance for drawing to. If my hardware acceleration is not enabled now, or by default, what would I have to do to enable it? 2) I have seen a couple articles here and there about the difference between a BufferedImage and VolatileImage, mainly saying that VolatileImage is the hardware accelerated image and is stored in VRAM for fast copy-from operations. However, I have also found some instances where BufferedImage is said to be hardware accelerated as well. Is BufferedImage hardware accelerated as well in my environment? What would be the advantage of using a VolatileImage if both types are hardware accelerated? My main assumption for the advantage of having a VolatileImage in the case of both having acceleration is that VolatileImage is able to detect when its VRAM has been dumped. But if BufferedImage also support acceleration now, would it not have the same kind of detection built into it as well, just hidden from the user, in case that the memory is dumped? 3) Is there any advantage to using someGraphicsConfiguration.getCompatibleImage/getCompatibleVolatileImage() as opposed to ImageIO.read() In a tutorial I have been reading for some general concepts about setting up the rendering window properly (tutorial) it uses the getCompatibleImage method, which I believe returns a BufferedImage, to get their "hardware accelerated" images for fast drawing, which ties into question 2 about if it is hardware accelerated. 4) This is less hardware acceleration, but it is something I have been curious about: do I need to order which graphics get drawn? I know that when using OpenGL via C/C++ it is best to make sure that the same graphic is drawn in all the locations it needs to be drawn at once to reduce the number of times the current texture needs to be switch. From what I have read, it seems as if Java will take care of this for me and make sure things are drawn in the most optimal fashion, but again, nothing has ever said anything like this clearly. 5) What AWT/Swing classes support hardware acceleration, and which ones should be used? I am currently using a class that extends JFrame to create a window, and adding a Canvas to it from which I create a BufferStrategy. Is this good practice, or is there some other type of way I should be implementing this? Thank you very much for your time, and I hope I provided clear questions and enough information for you to answer my several questions.

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• Efficiency of data structures in C99 (possibly affected by endianness)

  - by Ninefingers

  Hi All, I have a couple of questions that are all inter-related. Basically, in the algorithm I am implementing a word w is defined as four bytes, so it can be contained whole in a uint32_t. However, during the operation of the algorithm I often need to access the various parts of the word. Now, I can do this in two ways: uint32_t w = 0x11223344; uint8_t a = (w & 0xff000000) >> 24; uint8_t b = (w & 0x00ff0000) >> 16; uint8_t b = (w & 0x0000ff00) >> 8; uint8_t d = (w & 0x000000ff); However, part of me thinks that isn't particularly efficient. I thought a better way would be to use union representation like so: typedef union { struct { uint8_t d; uint8_t c; uint8_t b; uint8_t a; }; uint32_t n; } word32; Using this method I can assign word32 w = 0x11223344; then I can access the various parts as I require (w.a=11 in little endian). However, at this stage I come up against endianness issues, namely, in big endian systems my struct is defined incorrectly so I need to re-order the word prior to it being passed in. This I can do without too much difficulty. My question is, then, is the first part (various bitwise ands and shifts) efficient compared to the implementation using a union? Is there any difference between the two generally? Which way should I go on a modern, x86_64 processor? Is endianness just a red herring here? I could inspect the assembly output of course, but my knowledge of compilers is not brilliant. I would have thought a union would be more efficient as it would essentially convert to memory offsets, like so: mov eax, [r9+8] Would a compiler realise that is what happening in the bit-shift case above? If it matters, I'm using C99, specifically my compiler is clang (llvm). Thanks in advance.

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• Alternatives to requiring users to register for an account?

  - by jamieb

  I'm working on a side project to build a new web app idea of mine. For the sake of discussion, let's say this app displays a random photograph of a famous work of art. On a scale of 1 to 5, users are asked to rate how well they like each piece of art, and then are shown the next photo. Eventually, the app is able to get an sense of the person's style and is able to recommend artwork that he/she may find pleasing. The whole concept is similar to Netflix. I understand how to do all the preference matching logic (although not as sophisticated as Netflix). But I'd like to find a way to do this without requiring that users create an account first. This is a novelty website that a typical user might use only a handful of times. Requiring registration is overkill and will likely drastically reduce it's utility. I'd like to allow people to begin rating artwork within five seconds of their initial pageview, yet maintain the integrity of the voting (since recommendations are predicated on how other people have rated the various pieces of artwork). Can it be done? Some ideas: OpenID. The perfect solution except for the fact that it's not wildly used and my target audience isn't the most technically adept demographic. Text message. User inputs phone number and is texted a four digit code to key into the web app. Quick, easy, and great way to limit abuse. However, privacy concerns abound... people are probably even less likely to give me their phone number than their email address. Facebook login. I personally don't have a Facebook account due to privacy concerns. And I'd really hate to support such a proprietary platform. Hash code/Bookmark. Vistor's initial pageview generates a 5 or 6 digit alphanumeric code that is embedded in each subsequent URL. They can bookmark any page to save their state. Good: Very simple system that doesn't require any user action. Bad: Very easy to stuff the ballot box, might be difficult to account for users sharing the link containing their ID code via email or social networking sites.

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• Bulk inserts into sqlite db on the iphone...

  - by akaii

  I'm inserting a batch of 100 records, each containing a dictonary containing arbitrarily long HTML strings, and by god, it's slow. On the iphone, the runloop is blocking for several seconds during this transaction. Is my only recourse to use another thread? I'm already using several for acquiring data from HTTP servers, and the sqlite documentation explicitly discourages threading with the database, even though it's supposed to be thread-safe... Is there something I'm doing extremely wrong that if fixed, would drastically reduce the time it takes to complete the whole operation? NSString* statement; statement = @"BEGIN EXCLUSIVE TRANSACTION"; sqlite3_stmt *beginStatement; if (sqlite3_prepare_v2(database, [statement UTF8String], -1, &beginStatement, NULL) != SQLITE_OK) { printf("db error: %s\n", sqlite3_errmsg(database)); return; } if (sqlite3_step(beginStatement) != SQLITE_DONE) { sqlite3_finalize(beginStatement); printf("db error: %s\n", sqlite3_errmsg(database)); return; } NSTimeInterval timestampB = [[NSDate date] timeIntervalSince1970]; statement = @"INSERT OR REPLACE INTO item (hash, tag, owner, timestamp, dictionary) VALUES (?, ?, ?, ?, ?)"; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(database, [statement UTF8String], -1, &compiledStatement, NULL) == SQLITE_OK) { for(int i = 0; i < [items count]; i++){ NSMutableDictionary* item = [items objectAtIndex:i]; NSString* tag = [item objectForKey:@"id"]; NSInteger hash = [[NSString stringWithFormat:@"%@%@", tag, ownerID] hash]; NSInteger timestamp = [[item objectForKey:@"updated"] intValue]; NSData *dictionary = [NSKeyedArchiver archivedDataWithRootObject:item]; sqlite3_bind_int( compiledStatement, 1, hash); sqlite3_bind_text( compiledStatement, 2, [tag UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_text( compiledStatement, 3, [ownerID UTF8String], -1, SQLITE_TRANSIENT); sqlite3_bind_int( compiledStatement, 4, timestamp); sqlite3_bind_blob( compiledStatement, 5, [dictionary bytes], [dictionary length], SQLITE_TRANSIENT); while(YES){ NSInteger result = sqlite3_step(compiledStatement); if(result == SQLITE_DONE){ break; } else if(result != SQLITE_BUSY){ printf("db error: %s\n", sqlite3_errmsg(database)); break; } } sqlite3_reset(compiledStatement); } timestampB = [[NSDate date] timeIntervalSince1970] - timestampB; NSLog(@"Insert Time Taken: %f",timestampB); // COMMIT statement = @"COMMIT TRANSACTION"; sqlite3_stmt *commitStatement; if (sqlite3_prepare_v2(database, [statement UTF8String], -1, &commitStatement, NULL) != SQLITE_OK) { printf("db error: %s\n", sqlite3_errmsg(database)); } if (sqlite3_step(commitStatement) != SQLITE_DONE) { printf("db error: %s\n", sqlite3_errmsg(database)); } sqlite3_finalize(beginStatement); sqlite3_finalize(compiledStatement); sqlite3_finalize(commitStatement);

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• Queue ExternalInterface calls to Flash Object in UpdatePanel - Needs Improvement?

  - by Laramie

  A Flash (actually Flex) object is created on an ASP.Net page within an Update Panel using a modified version of the embedCallAC_FL_RunContent.js script so it can be written in dynamically. It is re-created with this script with each partial postback to that panel. There are also other Update Panels on the page. With some postbacks (partial and full), External Interface calls such as $get('FlashObj').ExternalInterfaceFunc('arg1', 0, true); are prepared server-side and added to the page using ScriptManager.RegisterStartupScript. They're embedded in a function and stuffed into Sys.Application's load event, for example Sys.Application.add_load(funcContainingExternalInterfaceCalls). The problem is that because the Flash object's state state may change with each partial postback, the Flash (Flex) object and/or External Interface may not be ready or even exist yet in the DOM when the JavaScript - Flash External Interface call is made. It results in an "Object doesn't support this property or method" exception. I have a working strategy to make the ExternalInterface calls immediately if Flash is ready or else queue them until such time that Flash announces its readiness. //Called when the Flash object is initialized and can accept ExternalInterfaceCalls var flashReady = false; //Called by Flash when object is fully initialized function setFlashReady() { flashReady = true; //Make any queued ExternalInterface calls, then dequeue while (extIntQueue.length > 0) (extIntQueue.shift())(); } var extIntQueue = []; function callExternalInterface(flashObjName, funcName, args) { //reference to the wrapped ExternalInterface Call var wrapped = extWrap(flashObjName, funcName, args); //only procede with ExternalInterface call if the global flashReady variable has been set if (flashReady) { wrapped(); } else { //queue the function so when flashReady() is called next, the function is called and the aruments are passed. extIntQueue.push(wrapped); } } //bundle ExtInt call and hold variables in a closure function extWrap(flashObjName, funcName, args) { //put vars in closure return function() { var funcCall = '$get("' + flashObjName + '").' + funcName; eval(funcCall).apply(this, args); } } I set the flashReady var to dirty whenever I update the Update Panel that contains the Flash (Flex) object. ScriptManager.RegisterClientScriptBlock(parentContainer, parentContainer.GetType(), "flashReady", "flashReady = false;", true); I'm pleased that I got it to work, but it feels like a hack. I am still on the learning curve with respect to concepts like closures why "eval()" is apparently evil, so I'm wondering if I'm violating some best practice or if this code should be improved, if so how? Thanks.

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