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• Moving from Tortoise to TFS

  - by MarkPearl

  The Past A few years ago my small software company made the jump from storing code on a shared folder to source code control. At the time we had evaluated a few of the options and settled on Tortoise SVN. The main motivation for going the SVN route was that we found a great plugin for Visual Studio that allowed us to avoid the command prompt for uploading changes (like I said we are windows programmers… command prompt bad!! ) and it was free. Up to now we have been pretty happy with SVN as it removed many of the worries that I had about how safe my code was on a shared folder and also gave us the opportunity to safely have several developers work on the same project at the same time. The only times when we have been unhappy has been when we have had SVN hell days – which pretty much occur when you are doing something out of the norm and suddenly SVN just won’t resolve conflicts or something along those lines. This happens once every 4 or 5 months and is not necessarily a problem caused directly by SVN – but a problem augmented by SVN. When you have SVN hell days you want to curse SVN! With that in mind I recently have been relooking at our source code control. I have explored using GIT and was very impressed by it and have also looked at TFS. From a source code control perspective I don’t want to get into a heated discussion on which one is better – but I do want to mention that I wear two hats in my organization – software developer & manager, and with the manager hat on I tend to sway the TFS route. So when I was given a coupon to test DiscountASP.Net Team Foundation Server Service for a year, I thought it was the perfect opportunity to try TFS in a distributed environment and also make the first step towards having an integrated development management system. Some of the things that appeal to me about DiscountASP’s offering are the following… Basic management / planning facilities like to do lists inside Visual Studio Daily backup of data on the server – we are developers, not IT managers and so the more of this I could outsource the better Distributed solution – all of us work remotely and so this was a big one as well. Registering and Setting Up with DiscountASP.NET The whole registration process was simple and intuitive. The web interface is not the most visually impressive one, but it is functional and a few seconds after I clicked the last submit button a email was sitting in my inbox giving me my control panel username and suggesting that I read the “Getting Started” article. The getting started article was easy to read and understand so no complaints there either. Next to set my dev environment to work. With a few references to the getting started article I had completed the whole setup process in a matter of minutes. Ten minutes after initiating the whole thing I was logged into VS2010 and creating my first TFS project. With the service that I signed up for, I have access for 5 users – which is sufficient for my internal needs. So from what I can tell, to set the rest of us up on the system I just need to supply them with their user credentials and url. My Concerns Resolved 1) Security So, a few concerns I had about the service. First and foremost – is it secure? I would hate for someone to get access to our code and the whole idea of putting it up on the internet is a concern for me. Turning to the Knowledge Base on the DiscountASP website this is one of the first question I can see answered. According to them it is secure. I have extracted their comment below regarding this. Our TFS hosting service is secure. We only accept HTTPS connections ensuring that any client-server data transmission is encrypted. At the network level, all of our systems are protected by multiple Juniper firewalls, Tipping Point's Intrusion Detection System (see Tipping Point's case study of our use here), and we also employ DDoS mitigation to add extra layers of security. Additionally, physical access to the servers is tightly restricted. Please see the security section of this Knowledge Base article for further details. 2) Web Portal Access The other big concern I have is regarding web portal access. In the ideal world I would like to be able to give my end users access to a web portal for reporting bugs etc. When I initially read through the FAQ of the site it mentioned that there was web portal access – but from what I can see this is just for “users”. Since I am limited to 5 users for the account, it would not be practical to set up external users that we could get feedback from on bugs etc. I would be interested if this is possible – and if so if someone could post it in the comments it would be much appreciated. If this isn’t possible, it is a slight let down as we rely heavily on end user feedback to get feedback and it would have been ideal to have gotten this within the service. Other than those two items, I didn’t have any real concerns that were unresolved. So where do I go from here? So time passed by from the initial writing of this post and as work whirred in and out of my inbox I have still not had a proper opportunity to give the service a test run. Recently though things have began to slow down and then surprise surprise I had another SVN Hell day. With that experience I had a new found resolve to get our team on TFS and so today we are going to start to use the service as a team. I am hoping that I do not have TFS hell days – but if I do, I will be sure to write about them. In short - the verdict is still out on whether this service is going to be invaluable to my business or whether it will create more headaches than it is worth BUT I am hopping it will be an invaluable service. I will only really be able to determine that in a few months… till then!

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• Can Google Employees See My Saved Google Chrome Passwords?

  - by Jason Fitzpatrick

  Storing your passwords in your web browser seems like a great time saver, but are the passwords secure and inaccessible to others (even employees of the browser company) when squirreled away? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader MMA is curious if Google employees have (or could have) access to the passwords he stores in Google Chrome: I understand that we are really tempted to save our passwords in Google Chrome. The likely benefit is two fold, You don’t need to (memorize and) input those long and cryptic passwords. These are available wherever you are once you log in to your Google account. The last point sparked my doubt. Since the password is available anywhere, the storage must in some central location, and this should be at Google. Now, my simple question is, can a Google employee see my passwords? Searching over the Internet revealed several articles/messages. Do you save passwords in Chrome? Maybe you should reconsider: Talks about your passwords being stolen by someone who has access to your computer account. Nothing mentioned about the central storage security and vulnerability. There is even a response from Chrome browser security tech lead about the first issue. Chrome’s insane password security strategy: Mostly along the same line. You can steal password from somebody if you have access to the computer account. How to Steal Passwords Saved in Google Chrome in 5 Simple Steps: Teaches you how to actually perform the act mentioned in the previous two when you have access to somebody else’s account. There are many more (including this one at this site), mostly along the same line, points, counter-points, huge debates. I refrain from mentioning them here, simply carry a search if you want to find them. Coming back to my original query, can a Google employee see my password? Since I can view the password using a simple button, definitely they can be unhashed (decrypted) even if encrypted. This is very different from the passwords saved in Unix-like OS’s where the saved password can never be seen in plain text. They use a one-way encryption algorithm to encrypt your passwords. This encrypted password is then stored in the passwd or shadow file. When you attempt to login, the password you type in is encrypted again and compared with the entry in the file that stores your passwords. If they match, it must be the same password, and you are allowed access. Thus, a superuser can change my password, can block my account, but he can never see my password. So are his concerns well founded or will a little insight dispel his worry? The Answer SuperUser contributor Zeel helps put his mind at ease: Short answer: No* Passwords stored on your local machine can be decrypted by Chrome, as long as your OS user account is logged in. And then you can view those in plain text. At first this seems horrible, but how did you think auto-fill worked? When that password field gets filled in, Chrome must insert the real password into the HTML form element – or else the page wouldn’t work right, and you could not submit the form. And if the connection to the website is not over HTTPS, the plain text is then sent over the internet. In other words, if chrome can’t get the plain text passwords, then they are totally useless. A one way hash is no good, because we need to use them. Now the passwords are in fact encrypted, the only way to get them back to plain text is to have the decryption key. That key is your Google password, or a secondary key you can set up. When you sign into Chrome and sync the Google servers will transmit the encrypted passwords, settings, bookmarks, auto-fill, etc, to your local machine. Here Chrome will decrypt the information and be able to use it. On Google’s end all that info is stored in its encrpyted state, and they do not have the key to decrypt it. Your account password is checked against a hash to log in to Google, and even if you let chrome remember it, that encrypted version is hidden in the same bundle as the other passwords, impossible to access. So an employee could probably grab a dump of the encrypted data, but it wouldn’t do them any good, since they would have no way to use it.* So no, Google employees can not** access your passwords, since they are encrypted on their servers. * However, do not forget that any system that can be accessed by an authorized user can be accessed by an unauthorized user. Some systems are easier to break than other, but none are fail-proof. . . That being said, I think I will trust Google and the millions they spend on security systems, over any other password storage solution. And heck, I’m a wimpy nerd, it would be easier to beat the passwords out of me than break Google’s encryption. ** I am also assuming that there isn’t a person who just happens to work for Google gaining access to your local machine. In that case you are screwed, but employment at Google isn’t actually a factor any more. Moral: Hit Win + L before leaving machine. While we agree with zeel that it’s a pretty safe bet (as long as your computer is not compromised) that your passwords are in fact safe while stored in Chrome, we prefer to encrypt all our logins and passwords in a LastPass vault. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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• JavaOne Session Report: “50 Tips in 50 Minutes for GlassFish Fans”

  - by Janice J. Heiss

  At JavaOne 2012 on Monday, Oracle’s Engineer Chris Kasso, and Technology Evangelist Arun Gupta, presented a head-spinning session (CON4701) in which they offered 50 tips for GlassFish fans. Kasso and Gupta alternated back and forth with each presenting 10 tips at a time. An audience of about (appropriately) 50 attentive and appreciative developers was on hand in what has to be one of the most information-packed sessions ever at JavaOne!Aside: I experienced one of the quiet joys of JavaOne when, just before the session began, I spotted Java Champion and JavaOne Rock Star Adam Bien sitting nearby – Adam is someone I have been fortunate to know for many years.GlassFish is a freely available, commercially supported Java EE reference implementation. The session prioritized quantity of tips over depth of information and offered tips that are intended for both seasoned and new users, that are meant to increase the range of functional options available to GlassFish users. The focus was on lesser-known dimensions of GlassFish. Attendees were encouraged to pursue tips that contained new information for them. All 50 tips can be accessed here.Below are several examples of more elaborate tips and a final practical tip on how to get in touch with these folks. Tip #1: Using the login Command * To execute a remote command with asadmin you must provide the admin's user name and password.* The login command allows you to store the login credentials to be reused in subsequent commands.* Can be logged into multiple servers (distinguish by host and port). Example:     % asadmin --host ouch login     Enter admin user name [default: admin]>     Enter admin password>     Login information relevant to admin user name [admin]     for host [ouch] and admin port [4848] stored at     [/Users/ckasso/.asadminpass] successfully.     Make sure that this file remains protected.     Information stored in this file will be used by     asadmin commands to manage the associated domain.     Command login executed successfully.     % asadmin --host ouch list-clusters     c1 not running     Command list-clusters executed successfully.Tip #4: Using the AS_DEBUG Env Variable* Environment variable to control client side debug output* Exposes: command processing info URL used to access the command:                           http://localhost:4848/__asadmin/uptime Raw response from the server Example:   % export AS_DEBUG=true  % asadmin uptime  CLASSPATH= ./../glassfish/modules/admin-cli.jar  Commands: [uptime]  asadmin extension directory: /work/gf-3.1.2/glassfish3/glassfish/lib/asadm      ------- RAW RESPONSE  ---------   Signature-Version: 1.0   message: Up 7 mins 10 secs   milliseconds_value: 430194   keys: milliseconds   milliseconds_name: milliseconds   use-main-children-attribute: false   exit-code: SUCCESS  ------- RAW RESPONSE  ---------Tip #11: Using Password Aliases * Some resources require a password to access (e.g. DB, JMS, etc.).* The resource connector is defined in the domain.xml.Example:Suppose the DB resource you wish to access requires an entry like this in the domain.xml:     <property name="password" value="secretp@ssword"/>But company policies do not allow you to store the password in the clear.* Use password aliases to avoid storing the password in the domain.xml* Create a password alias:     % asadmin create-password-alias DB_pw_alias     Enter the alias password>     Enter the alias password again>     Command create-password-alias executed successfully.* The password is stored in domain's encrypted keystore.* Now update the password value in the domain.xml:     <property name="password" value="${ALIAS=DB_pw_alias}"/>Tip #21: How to Start GlassFish as a Service * Configuring a server to automatically start at boot can be tedious.* Each platform does it differently.* The create-service command makes this easy.   Windows: creates a Windows service Linux: /etc/init.d script Solaris: Service Management Facility (SMF) service * Must execute create-service with admin privileges.* Can be used for the DAS or instances* Try it first with the --dry-run option.* There is a (unsupported) _delete-serverExample:     # asadmin create-service domain1     The Service was created successfully. Here are the details:     Name of the service:application/GlassFish/domain1     Type of the service:Domain     Configuration location of the service:/work/gf-3.1.2.2/glassfish3/glassfish/domains     Manifest file location on the system:/var/svc/manifest/application/GlassFish/domain1_work_gf-3.1.2.2_glassfish3_glassfish_domains/Domain-service-smf.xml.     You have created the service but you need to start it yourself. Here are the most typical Solaris commands of interest:     * /usr/bin/svcs  -a | grep domain1  // status     * /usr/sbin/svcadm enable domain1 // start     * /usr/sbin/svcadm disable domain1 // stop     * /usr/sbin/svccfg delete domain1 // uninstallTip #34: Posting a Command via REST* Use wget/curl to execute commands on the DAS.Example:  Deploying an application   % curl -s -S \       -H 'Accept: application/json' -X POST \       -H 'X-Requested-By: anyvalue' \       -F id=@/path/to/application.war \       -F force=true http://localhost:4848/management/domain/applications/application* Use @ before a file name to tell curl to send the file's contents.* The force option tells GlassFish to force the deployment in case the application is already deployed.* Use wget/curl to execute commands on the DAS.Example:  Deploying an application   % curl -s -S \       -H 'Accept: application/json' -X POST \       -H 'X-Requested-By: anyvalue' \       -F id=@/path/to/application.war \       -F force=true http://localhost:4848/management/domain/applications/application* Use @ before a file name to tell curl to send the file's contents.* The force option tells GlassFish to force the deployment in case the application is already deployed.Tip #46: Upgrading to a Newer Version * Upgrade applications and configuration from an earlier version* Upgrade Tool: Side-by-side upgrade– GUI: asupgrade– CLI: asupgrade --c– What happens ?* Copies older source domain -> target domain directory* asadmin start-domain --upgrade* Update Tool and pkg: In-place upgrade– GUI: updatetool, install all Available Updates– CLI: pkg image-update– Upgrade the domain* asadmin start-domain --upgradeTip #50: How to reach us?* GlassFish Forum: http://www.java.net/forums/glassfish/glassfish* [email protected]* @glassfish* facebook.com/glassfish* youtube.com/GlassFishVideos* blogs.oracle.com/theaquariumArun Gupta acknowledged that their method of presentation was experimental and actively solicited feedback about the session. The best way to reach them is on the GlassFish user forum.In addition, check out Gupta’s new book Java EE 6 Pocket Guide.

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• Making Those PanelBoxes Behave

  - by Duncan Mills

  I have a little problem to solve earlier this week - misbehaving <af:panelBox> components... What do I mean by that? Well here's the scenario, I have a page fragment containing a set of panelBoxes arranged vertically. As it happens, they are stamped out in a loop but that does not really matter. What I want to be able to do is to provide the user with a simple UI to close and open all of the panelBoxes in concert. This could also apply to showDetailHeader and similar items with a disclosed attrubute, but in this case it's good old panelBoxes.  Ok, so the basic solution to this should be self evident. I can set up a suitable scoped managed bean that the panelBoxes all refer to for their disclosed attribute state. Then the open all / close commandButtons in the UI can simply set the state of that bean for all the panelBoxes to pick up via EL on their disclosed attribute. Sound OK? Well that works basically without a hitch, but turns out that there is a slight problem and this is where the framework is attempting to be a little too helpful. The issue is that is the user manually discloses or hides a panelBox then that will override the value that the EL is setting. So for example. I start the page with all panelBoxes collapsed, all set by the EL state I'm storing on the session I manually disclose panelBox no 1. I press the Expand All button - all works as you would hope and all the panelBoxes are now disclosed, including of course panelBox 1 which I just expanded manually. Finally I press the Collapse All button and everything collapses except that first panelBox that I manually disclosed.  The problem is that the component remembers this manual disclosure and that overrides the value provided by the expression. If I change the viewId (navigate away and back) then the panelBox will start to behave again, until of course I touch it again! Now, the more astute amoungst you would think (as I did) Ah, sound like the MDS personalizaton stuff is getting in the way and the solution should simply be to set the dontPersist attribute to disclosed | ALL. Alas this does not fix the issue.  After a little noodling on the best way to approach this I came up with a solution that works well, although if you think of an alternative way do let me know. The principle is simple. In the disclosureListener for the panelBox I take a note of the clientID of the panelBox component that has been touched by the user along with the state. This all gets stored in a Map of Booleans in ViewScope which is keyed by clientID and stores the current disclosed state in the Boolean value.  The listener looks like this (it's held in a request scope backing bean for the page): public void handlePBDisclosureEvent(DisclosureEvent disclosureEvent) { String clientId = disclosureEvent.getComponent().getClientId(FacesContext.getCurrentInstance()); boolean state = disclosureEvent.isExpanded(); pbState.addTouchedPanelBox(clientId, state); } The pbState variable referenced here is a reference to the bean which will hold the state of the panelBoxes that lives in viewScope (recall that everything is re-set when the viewid is changed so keeping this in viewScope is just fine and cleans things up automatically). The addTouchedPanelBox() method looks like this: public void addTouchedPanelBox(String clientId, boolean state) { //create the cache if needed this is just a Map<String,Boolean> if (_touchedPanelBoxState == null) { _touchedPanelBoxState = new HashMap<String, Boolean>(); } // Simply put / replace _touchedPanelBoxState.put(clientId, state); } So that's the first part, we now have a record of every panelBox that the user has touched. So what do we do when the Collapse All or Expand All buttons are pressed? Here we do some JavaScript magic. Basically for each clientID that we have stored away, we issue a client side disclosure event from JavaScript - just as if the user had gone back and changed it manually. So here's the Collapse All button action: public String CloseAllAction() { submitDiscloseOverride(pbState.getTouchedClientIds(true), false); _uiManager.closeAllBoxes(); return null; }  The _uiManager.closeAllBoxes() method is just manipulating the master-state that all of the panelBoxes are bound to using EL. The interesting bit though is the line:  submitDiscloseOverride(pbState.getTouchedClientIds(true), false); To break that down, the first part is a call to that viewScoped state holder to ask for a list of clientIDs that need to be "tweaked": public String getTouchedClientIds(boolean targetState) { StringBuilder sb = new StringBuilder(); if (_touchedPanelBoxState != null && _touchedPanelBoxState.size() > 0) { for (Map.Entry<String, Boolean> entry : _touchedPanelBoxState.entrySet()) { if (entry.getValue() == targetState) { if (sb.length() > 0) { sb.append(','); } sb.append(entry.getKey()); } } } return sb.toString(); } You'll notice that this method only processes those panelBoxes that will be in the wrong state and returns those as a comma separated list. This is then processed by the submitDiscloseOverride() method: private void submitDiscloseOverride(String clientIdList, boolean targetDisclosureState) { if (clientIdList != null && clientIdList.length() > 0) { FacesContext fctx = FacesContext.getCurrentInstance(); StringBuilder script = new StringBuilder(); script.append("overrideDiscloseHandler('"); script.append(clientIdList); script.append("',"); script.append(targetDisclosureState); script.append(");"); Service.getRenderKitService(fctx, ExtendedRenderKitService.class).addScript(fctx, script.toString()); } } This method constructs a JavaScript command to call a routine called overrideDiscloseHandler() in a script attached to the page (using the standard <af:resource> tag). That method parses out the list of clientIDs and sends the correct message to each one: function overrideDiscloseHandler(clientIdList, newState) { AdfLogger.LOGGER.logMessage(AdfLogger.INFO, "Disclosure Hander newState " + newState + " Called with: " + clientIdList); //Parse out the list of clientIds var clientIdArray = clientIdList.split(','); for (var i = 0; i < clientIdArray.length; i++){ var panelBox = flipPanel = AdfPage.PAGE.findComponentByAbsoluteId(clientIdArray[i]); if (panelBox.getComponentType() == "oracle.adf.RichPanelBox"){ panelBox.broadcast(new AdfDisclosureEvent(panelBox, newState)); } }  }  So there you go. You can see how, with a few tweaks the same code could be used for other components with disclosure that might suffer from the same problem, although I'd point out that the behavior I'm working around here us usually desirable. You can download the running example (11.1.2.2) from here. 

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 4

  - by MarkPearl

  Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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• All downloads being interrupted

  - by Jake

  System: Windows 7 Professional 64bit. 8GB RAM, Intel i5-2400 CPU, +300GB free on the hard drive. AVG Internet Security 2012 (enabled & disabled, with firewall enabled and disabled - no effect for either). This computer is less than a year old. Network: This problem is occurring on a single computer on a network with multiple computers. The router is a Motorola Netopia 3347-02 (DSL Modem/Wireless Router combined). The computer is plugged in directly to the modem, other computers are using the wireless successfully. The router has been reset. The only thing odd about the connection between the router and computer is that it is configured to allow RDP through, so it is assigned a static IP by the router and port forwarding is enabled for port 3389. Also, though I doubt it matters, a second wireless router is active behind this router providing a second network that some computers in the area use without issues. Details: All downloads initiated on this specific computer eventually fail, this includes streaming from youtube, specialized downloads (itunes), downloads from websites, FTP downloads, etc. Failure occurs with all browsers, but in chrome this is the process it takes: 1) Download begins normally, 2) At some point between (observed) 7MBs and 229MBs the download stops progressing (at this point, if watching chrome's task manager, you can see the network activity for the downloading tab drop to 0kps), 3) for some time the download sits there still attempting to complete, but will eventually display "123,049,871/0 B, Interrupted" (where the number is whatever it actually got to). The file I am using to test this is a very large .zip file located on a server I control, but the problem seems to occur on any site. The amount downloaded is completely random, and seems to be more time-based than anything (if I start a download immediately after the last one fails, it tends to get further than the last one). Small files can get through for this reason, though they can fail as well. In a test where I simultaneously downloaded the same file via HTTP (chrome) and FTP (windows explorer), both downloads failed at the same instant, though explorer displayed "Connection timed out" several minutes before chrome finally showed the download as interrupted. Other things I have tried based on advice given to people with similar/identical problems: Setting my MTU to 1492 (as described here: http://blog.thecompwiz.com/2011/08/networking-issues.html) Disabling write caching to the hard drive storing the download on an external device successfully transmitted +1GB file from one computer on the same network to this computer disabling indexing in the folder the download was being stored in disabling all security software checked to make sure all drivers were up to date read about 50 accounts with nearly exact descriptions of what I'm experiencing, none of which had a solution given Running Processes: Image Name PID Session Name Session# Mem Usage ========================= ======== ================ =========== ============ System Idle Process 0 Services 0 24 K System 4 Services 0 104,836 K smss.exe 332 Services 0 1,276 K csrss.exe 764 Services 0 5,060 K wininit.exe 820 Services 0 4,748 K csrss.exe 844 Console 1 23,764 K services.exe 876 Services 0 11,856 K lsass.exe 892 Services 0 14,420 K lsm.exe 900 Services 0 7,820 K winlogon.exe 944 Console 1 7,716 K svchost.exe 428 Services 0 12,744 K svchost.exe 796 Services 0 12,240 K svchost.exe 1036 Services 0 22,372 K svchost.exe 1084 Services 0 174,132 K svchost.exe 1112 Services 0 56,144 K svchost.exe 1288 Services 0 18,640 K svchost.exe 1404 Services 0 29,616 K spoolsv.exe 1576 Services 0 25,924 K svchost.exe 1616 Services 0 12,788 K AppleMobileDeviceService. 1728 Services 0 9,796 K avgwdsvc.exe 1820 Services 0 8,268 K mDNSResponder.exe 1844 Services 0 5,832 K w3dbsmgr.exe 1108 Services 0 43,760 K QBCFMonitorService.exe 1336 Services 0 16,408 K svchost.exe 2404 Services 0 28,240 K taskhost.exe 3020 Console 1 12,372 K dwm.exe 2280 Console 1 5,968 K explorer.exe 2964 Console 1 152,476 K WUDFHost.exe 3316 Services 0 6,740 K svchost.exe 3408 Services 0 5,556 K RAVCpl64.exe 3684 Console 1 13,864 K igfxtray.exe 3700 Console 1 7,804 K hkcmd.exe 3772 Console 1 7,868 K igfxpers.exe 3788 Console 1 10,940 K sidebar.exe 3836 Console 1 84,400 K chrome.exe 3964 Console 1 19,640 K pptd40nt.exe 4068 Console 1 5,156 K acrotray.exe 3908 Console 1 14,676 K avgtray.exe 3872 Console 1 9,508 K jusched.exe 4076 Console 1 4,412 K iTunesHelper.exe 1532 Console 1 87,308 K SearchIndexer.exe 3492 Services 0 36,948 K iPodService.exe 4136 Services 0 7,944 K BrccMCtl.exe 4276 Console 1 18,132 K splwow64.exe 4380 Console 1 32,600 K qbupdate.exe 4836 Console 1 24,236 K svchost.exe 4288 Services 0 20,700 K wmpnetwk.exe 3112 Services 0 9,516 K FNPLicensingService.exe 5248 Services 0 5,852 K QBW32.EXE 5508 Console 1 127,068 K QBDBMgrN.exe 5600 Services 0 42,252 K EXCEL.EXE 2512 Console 1 99,100 K LMS.exe 3188 Services 0 5,616 K UNS.exe 1600 Services 0 7,308 K axlbridge.exe 5260 Console 1 5,132 K chrome.exe 5888 Console 1 200,336 K chrome.exe 3536 Console 1 26,076 K chrome.exe 1952 Console 1 20,168 K chrome.exe 4596 Console 1 24,696 K chrome.exe 4292 Console 1 48,096 K chrome.exe 2796 Console 1 23,520 K Acrobat.exe 1240 Console 1 87,252 K 123w.exe 4892 Console 1 22,728 K calc.exe 1700 Console 1 12,636 K chrome.exe 1328 Console 1 28,888 K chrome.exe 3696 Console 1 47,012 K rundll32.exe 6320 Console 1 7,104 K chrome.exe 4928 Console 1 44,248 K AVGIDSAgent.exe 260 Services 0 12,940 K avgfws.exe 6052 Services 0 26,912 K avgnsa.exe 5064 Services 0 2,496 K avgrsa.exe 3088 Services 0 2,200 K avgcsrva.exe 2596 Services 0 380 K avgcsrva.exe 6948 Services 0 408 K StikyNot.exe 452 Console 1 14,772 K chrome.exe 4580 Console 1 28,200 K chrome.exe 4016 Console 1 57,756 K svchost.exe 7140 Services 0 4,500 K chrome.exe 6264 Console 1 56,824 K chrome.exe 7008 Console 1 56,896 K chrome.exe 2224 Console 1 38,032 K taskhost.exe 612 Console 1 7,228 K chrome.exe 6000 Console 1 10,928 K chrome.exe 2568 Console 1 43,052 K chrome.exe 272 Console 1 75,988 K chrome.exe 7328 Console 1 53,240 K PaprPort.exe 7976 Console 1 137,152 K pplinks.exe 7500 Console 1 14,052 K ppscanmg.exe 5744 Console 1 18,996 K taskeng.exe 7388 Console 1 6,308 K SearchProtocolHost.exe 8024 Services 0 8,804 K SearchFilterHost.exe 7232 Services 0 7,848 K chrome.exe 8016 Console 1 37,440 K cmd.exe 7692 Console 1 3,096 K conhost.exe 7516 Console 1 5,872 K tasklist.exe 8160 Console 1 5,772 K WmiPrvSE.exe 7684 Services 0 6,400 K Any help with this would be greatly appreciated, I've been beating my head against a wall over this all day. This computer serves dual purpose as the main company document server and the Owner's work computer, it's fairly important it be fully functional and I cannot figure this out.

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• Java 7 update 6 installation fails on Windows 7 when Chrome is default browser

  - by ali1234

  I am configuring a brand new Lenovo U410 system with Windows 7 Home Premium for a user. I received the system direct from the shop. As part of the configuration I installed Java using the online installer. This worked correctly. Later, due to a mistake I made, I needed to restore the system to factory default. The factory default FORMATS C:\ and puts back (supposedly) the exact factory configuration. However, after doing this, I was no longer able to install Java successfully using the same method I used before. Now, whenever I attempt to use the online Java installer, the following happens. First of all, a window always appears "Welcome to Java", "Downloading Java Installer...". After short time this window disappears and then one of three things happens: The very first time I do this after doing a factory reset, I get a Windows error report, which contains this information: Application Name: JavaSetup7u5.exe Application Version: 7.0.50.6 Application Timestamp: 4feacd84 Fault Module Name: JavaIC.dll Fault Module Version: 9.9.9.9 Fault Module Timestamp: 4f2343d6 Exception Offset: 000052cb Exception Code: c0000417 Exception Data: 00000000 OS Version: 6.1.7600.2.0.0.768.3 Locale ID: 1033 Additional Information 1: 773c Additional Information 2: 773cd78cf06816f8246f359fa270f3bb Additional Information 3: f51a Additional Information 4: f51aaea7d22f36fa9e3a626b5a5cd1c3 2. Subsequent runs produce either this error message: "Error: Java(TM) installer - Downloaded file C:\Users\\AppData\Local\Temp\fx-runtime.exe is corrupt." or Nothing happens at all. I Believe this is a red herring. Running the installer again causes a different error because the files were downloaded and the installer crashed before it could clean up. This isn't the actual problem, as when this happens the installer deletes the downloaded files, and then when you run it for the third time, it downloads everything again and does the javaic.dll crash. I suspect the downloader is appending to the existing files or something, causing the corruption. I have tried all of the above as Administrator and as a normal user. I have tried reseting the system to factory defaults several times. I have tried downloading with Chrome and Internet Explorer 9. I have tried uninstalling all anti-virus software and disabling the windows firewall entirely. The only thing which makes a difference is running the installer in Windows XP compatibility mode, which allows the installation to complete. I know I can workaround this error by using the offline installer so please don't post that as an answer. I am looking for an explanation of the root cause. Additionally, if I use the offline installer, the updater does not work. The updater also does not work if I install in XP mode. The updater fails because it works by just downloading the newest online setup and running it. Also remember that the installers are digitally signed. The signitures verify correctly so there is no way in hell that this is caused by corrupted downloads. Some theories I have: The Java setup files on java.com actually changed in between the first successful install and my later attempts. Seems unlikely as none of the version numbers have changed. However, I have seen a couple of reports of this error which showed up in the past 24 hours. This looks like the most likely explanation right now: http://www.oracle.com/us/corporate/press/1735645 - Oracle released 7 update 6 two days ago. Careful inspection of the installers reveal that they are in fact attempting to download .6, not .5 as the download page claims. Not actually correct. Only the update tool tries to install 7u6. The online installer still tries 7u5. However, 7u6 being released two days ago is too much of a coincidence to ignore. Update: The 7u6 online installer is available from Oracle technetwork. It crashes in exactly the same way. The factory reset software uses GMT-8 and I am on GMT-1. As a result, after factory reset, any software which cares to check would think that the system was restored 7 hours in the future, due to Window's awful policy of storing local time in the system clock. This could be confusing a certificate check or similar. Update: I discovered that this does cause Windows Update to fail. The workaround, setting the clock back before starting factory reset, does not enable Java to install correctly. The factory reset image isn't really the same as what is installed in the main partition when you buy the system. Naughty Lenovo. The installer appears to crash while installing or displaying something to do with the Ask.com toolbar. That seems to be what javaic.dll does. Microsoft Tuesday was the 14th. Some update in that could be causing this. However, I'm factory reseting the machine every time, so unless the patches get slipstreamed into the recovery image, or there is some mechanism by which they get silently installed even if updates are disabled, then I don't see how this can be the cause. Major breakthrough: The default browser on Lenovo systems is Google Chrome. I noticed that the JavaIC.dll "sponsor check" actually does a check on your default browser in order to decide which sponsor ad to display. Normally that would get you the Ask toolbar on IE9. But that toolbar doesn't work on Chrome, and so the installer tries to display a different ad. The different ad is what causes the crash. Changing the default browser to IE9 allows the installer to run correctly. So this looks like a genuine bug in the sponsor ad code in the installer, caused by a combination of Google Chrome default browser and not being in the US. (Installer also checks your location using IP geolocation service and displays different ads based on that.)

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• Can't configure PAM + LDAP on Debian Lenny - Getting error=49 on server logs

  - by Jorge Suárez de Lis

  I've been migrating some servers and desktops using Ubuntu 10.04 from getting the users from an old OpenLDAP implementation to a newer Centos Active Directory. I haven't had any problems so far, until I reached a Debian Lenny server. I've set up the server as the others, setting /etc/ldap.conf and /etc/ldap/ldap.conf. However, when I issue "getent passwd", I get nothing from the LDAP server. Reading the pam_ldap manpage, I realized that /etc/ldap.conf was not an accepted file by pam_ldap -it worked with Ubuntu though-, so I renamed it to /etc/pam_ldap.conf. Same result. However, once I've changed the name of this file, when I login using SSH I get this on the LDAP server logs: [20/Jul/2012:11:19:40 +0200] conn=16501 fd=155 slot=155 connection from x.x.x.50 to 10.1.176.237 [20/Jul/2012:11:19:40 +0200] conn=16501 op=0 BIND dn="uid=ubuntu,ou=Applications,ou=CITIUS,dc=inv,dc=usc,dc=es" method=128 version=3 [20/Jul/2012:11:19:40 +0200] conn=16501 op=0 RESULT err=0 tag=97 nentries=0 etime=0 dn="uid=ubuntu,ou=applications,ou=citius,dc=inv,dc=usc,dc=es" [20/Jul/2012:11:19:40 +0200] conn=16501 op=1 SRCH base="ou=People,ou=CITIUS,dc=inv,dc=usc,dc=es" scope=2 filter="(uid=jorge.suarez)" attrs=ALL [20/Jul/2012:11:19:40 +0200] conn=16501 op=1 RESULT err=0 tag=101 nentries=1 etime=0 notes=U [20/Jul/2012:11:19:40 +0200] conn=16501 op=2 BIND dn="uid=jorge.suarez,ou=People,ou=CITIUS,dc=inv,dc=usc,dc=es" method=128 version=3 [20/Jul/2012:11:19:40 +0200] conn=16501 op=2 RESULT err=49 tag=97 nentries=0 etime=0 The password isn't working. I don't know that could be wrong, anything else seems to be OK. That user/password is working from another clients: [20/Jul/2012:11:29:39 +0200] conn=16528 fd=188 slot=188 connection from x.x.x.224 to 10.1.176.237 [20/Jul/2012:11:29:39 +0200] conn=16528 op=0 BIND dn="uid=ubuntu,ou=Applications,ou=CITIUS,dc=inv,dc=usc,dc=es" method=128 version=3 [20/Jul/2012:11:29:39 +0200] conn=16528 op=0 RESULT err=0 tag=97 nentries=0 etime=0 dn="uid=ubuntu,ou=applications,ou=citius,dc=inv,dc=usc,dc=es" [20/Jul/2012:11:29:39 +0200] conn=16528 op=1 SRCH base="ou=People,ou=CITIUS,dc=inv,dc=usc,dc=es" scope=2 filter="(uid=jorge.suarez)" attrs=ALL [20/Jul/2012:11:29:39 +0200] conn=16528 op=1 RESULT err=0 tag=101 nentries=1 etime=0 notes=U [20/Jul/2012:11:29:39 +0200] conn=16528 op=2 BIND dn="uid=jorge.suarez,ou=People,ou=CITIUS,dc=inv,dc=usc,dc=es" method=128 version=3 [20/Jul/2012:11:29:39 +0200] conn=16528 op=2 RESULT err=0 tag=97 nentries=0 etime=0 dn="uid=jorge.suarez,ou=people,ou=citius,dc=inv,dc=usc,dc=es" I'm using SSHA for storing passwords on the LDAP server. Maybe this is not supported by Debian Lenny? On pam_ldap.conf, I've set up this, as in all the other servers: # Do not hash the password at all; presume # the directory server will do it, if # necessary. This is the default. pam_password md5 Also tried clear, but it didn't work. Anyways, it's weird that issuing getent passwd still gets me no users. However, if I use pamtest from the package libpam-dotfile to test login, it works. # pamtest ssh jorge.suarez Trying to authenticate <jorge.suarez> for service <ssh>. Password: Authentication successful. # pamtest foo jorge.suarez Trying to authenticate <jorge.suarez> for service <foo>. Password: Authentication successful. But "su" won't work also: # su jorge.suarez Id. descoñecido: jorge.suarez Just the output from getent passwd : # getent passwd root:x:0:0:root:/root:/bin/bash daemon:x:1:1:daemon:/usr/sbin:/bin/sh bin:x:2:2:bin:/bin:/bin/sh sys:x:3:3:sys:/dev:/bin/sh sync:x:4:65534:sync:/bin:/bin/sync games:x:5:60:games:/usr/games:/bin/sh man:x:6:12:man:/var/cache/man:/bin/sh lp:x:7:7:lp:/var/spool/lpd:/bin/sh mail:x:8:8:mail:/var/mail:/bin/sh news:x:9:9:news:/var/spool/news:/bin/sh uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh proxy:x:13:13:proxy:/bin:/bin/sh www-data:x:33:33:www-data:/var/www:/bin/sh backup:x:34:34:backup:/var/backups:/bin/sh list:x:38:38:Mailing List Manager:/var/list:/bin/sh irc:x:39:39:ircd:/var/run/ircd:/bin/sh gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh nobody:x:65534:65534:nobody:/nonexistent:/bin/sh libuuid:x:100:101::/var/lib/libuuid:/bin/sh Debian-exim:x:101:103::/var/spool/exim4:/bin/false statd:x:102:65534::/var/lib/nfs:/bin/false sshd:x:104:65534::/var/run/sshd:/usr/sbin/nologin luser:x:1000:1000:Usuario local de Burdeos,,,:/home/luser:/bin/bash messagebus:x:105:107::/var/run/dbus:/bin/false sge-admin:x:1001:1001:Administrador do SGE,,,:/home/cluster/sge-admin:/bin/bash ntp:x:107:110::/home/ntp:/bin/false haldaemon:x:108:111:Hardware abstraction layer,,,:/var/run/hald:/bin/false vde2-net:x:109:114::/var/run/vde2:/bin/false uml-net:x:110:115::/home/uml-net:/bin/false polkituser:x:111:116:PolicyKit,,,:/var/run/PolicyKit:/bin/false Debian-pxe:x:113:65534:Dummy user for Debian pxe package,,,:/home/Debian-pxe:/bin/false Nscd was stopped from the beginning.

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• iPhone Serialization problem

  - by Jenicek

  Hi, I need to save my own created class to file, I found on the internet, that good approach is to use NSKeyedArchiver and NSKeyedUnarchiver My class definition looks like this: @interface Game : NSObject <NSCoding> { NSMutableString *strCompleteWord; NSMutableString *strWordToGuess; NSMutableArray *arGuessedLetters; //This array stores characters NSMutableArray *arGuessedLettersPos; //This array stores CGRects NSInteger iScore; NSInteger iLives; NSInteger iRocksFallen; BOOL bGameCompleted; BOOL bGameOver; } I've implemented methods initWithCoder: and encodeWithCoder: this way: - (id)initWithCoder:(NSCoder *)coder { if([coder allowsKeyedCoding]) { strCompleteWord = [[coder decodeObjectForKey:@"CompletedWord"] copy]; strWordToGuess = [[coder decodeObjectForKey:@"WordToGuess"] copy]; arGuessedLetters = [[coder decodeObjectForKey:@"GuessedLetters"] retain]; // arGuessedLettersPos = [[coder decodeObjectForKey:@"GuessedLettersPos"] retain]; iScore = [coder decodeIntegerForKey:@"Score"]; iLives = [coder decodeIntegerForKey:@"Lives"]; iRocksFallen = [coder decodeIntegerForKey:@"RocksFallen"]; bGameCompleted = [coder decodeBoolForKey:@"GameCompleted"]; bGameOver = [coder decodeBoolForKey:@"GameOver"]; } else { strCompleteWord = [[coder decodeObject] retain]; strWordToGuess = [[coder decodeObject] retain]; arGuessedLetters = [[coder decodeObject] retain]; // arGuessedLettersPos = [[coder decodeObject] retain]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iScore]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iLives]; [coder decodeValueOfObjCType:@encode(NSInteger) at:&iRocksFallen]; [coder decodeValueOfObjCType:@encode(BOOL) at:&bGameCompleted]; [coder decodeValueOfObjCType:@encode(BOOL) at:&bGameOver]; } return self; } - (void)encodeWithCoder:(NSCoder *)coder { if([coder allowsKeyedCoding]) { [coder encodeObject:strCompleteWord forKey:@"CompleteWord"]; [coder encodeObject:strWordToGuess forKey:@"WordToGuess"]; [coder encodeObject:arGuessedLetters forKey:@"GuessedLetters"]; //[coder encodeObject:arGuessedLettersPos forKey:@"GuessedLettersPos"]; [coder encodeInteger:iScore forKey:@"Score"]; [coder encodeInteger:iLives forKey:@"Lives"]; [coder encodeInteger:iRocksFallen forKey:@"RocksFallen"]; [coder encodeBool:bGameCompleted forKey:@"GameCompleted"]; [coder encodeBool:bGameOver forKey:@"GameOver"]; } else { [coder encodeObject:strCompleteWord]; [coder encodeObject:strWordToGuess]; [coder encodeObject:arGuessedLetters]; //[coder encodeObject:arGuessedLettersPos]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iScore]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iLives]; [coder encodeValueOfObjCType:@encode(NSInteger) at:&iRocksFallen]; [coder encodeValueOfObjCType:@encode(BOOL) at:&bGameCompleted]; [coder encodeValueOfObjCType:@encode(BOOL) at:&bGameOver]; } } And I use these methods to archive and unarchive data: [NSKeyedArchiver archiveRootObject:currentGame toFile:strPath]; Game *currentGame = [NSKeyedUnarchiver unarchiveObjectWithFile:strPath]; I have two problems. 1) As you can see, lines with arGuessedLettersPos is commented, it's because every time I try to encode this array, error comes up(this archiver cannot encode structs), and this array is used for storing CGRect structs. I've seen solution on the internet. The thing is, that every CGRect in the array is converted to an NSString (using NSStringFromCGRect()) and then saved. Is it a good approach? 2)This is bigger problem for me. Even if I comment this line and then run the code successfully, then save(archive) the data and then try to load (unarchive) them, no data is loaded. There aren't any error but currentGame object does not have data that should be loaded. Could you please give me some advice? This is first time I'm using archivers and unarchivers. Thanks a lot for every reply.

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• Android: How to track down the origin of a InflateException?

  - by Janusz

  While starting my application I get the following warning in Logcat: 04-09 10:28:17.830: WARN/WindowManager(52): Exception when adding starting window 04-09 10:28:17.830: WARN/WindowManager(52): android.view.InflateException: Binary XML file line #24: Error inflating class <unknown> 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.createView(LayoutInflater.java:513) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56) 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:563) 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.inflate(LayoutInflater.java:385) 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.inflate(LayoutInflater.java:320) 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.inflate(LayoutInflater.java:276) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.internal.policy.impl.PhoneWindow.generateLayout(PhoneWindow.java:2153) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.internal.policy.impl.PhoneWindow.installDecor(PhoneWindow.java:2207) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.internal.policy.impl.PhoneWindow.getDecorView(PhoneWindow.java:1395) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.internal.policy.impl.PhoneWindowManager.addStartingWindow(PhoneWindowManager.java:818) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.server.WindowManagerService$H.handleMessage(WindowManagerService.java:8794) 04-09 10:28:17.830: WARN/WindowManager(52): at android.os.Handler.dispatchMessage(Handler.java:99) 04-09 10:28:17.830: WARN/WindowManager(52): at android.os.Looper.loop(Looper.java:123) 04-09 10:28:17.830: WARN/WindowManager(52): at com.android.server.WindowManagerService$WMThread.run(WindowManagerService.java:531) 04-09 10:28:17.830: WARN/WindowManager(52): Caused by: java.lang.reflect.InvocationTargetException 04-09 10:28:17.830: WARN/WindowManager(52): at android.widget.FrameLayout.<init>(FrameLayout.java:79) 04-09 10:28:17.830: WARN/WindowManager(52): at java.lang.reflect.Constructor.constructNative(Native Method) 04-09 10:28:17.830: WARN/WindowManager(52): at java.lang.reflect.Constructor.newInstance(Constructor.java:446) 04-09 10:28:17.830: WARN/WindowManager(52): at android.view.LayoutInflater.createView(LayoutInflater.java:500) 04-09 10:28:17.830: WARN/WindowManager(52): ... 13 more 04-09 10:28:17.830: WARN/WindowManager(52): Caused by: android.content.res.Resources$NotFoundException: Resource is not a Drawable (color or path): TypedValue{t=0x2/d=0x1010059 a=-1} 04-09 10:28:17.830: WARN/WindowManager(52): at android.content.res.Resources.loadDrawable(Resources.java:1677) 04-09 10:28:17.830: WARN/WindowManager(52): at android.content.res.TypedArray.getDrawable(TypedArray.java:548) 04-09 10:28:17.830: WARN/WindowManager(52): at android.widget.FrameLayout.<init>(FrameLayout.java:91) 04-09 10:28:17.830: WARN/WindowManager(52): ... 17 more My Application starts with the following splash screen: <?xml version="1.0" encoding="utf-8"?> <ScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:windowBackground="@color/white" android:background="@color/white" android:layout_width="fill_parent" android:layout_height="fill_parent" android:foregroundGravity="center"> <ImageView android:id="@+id/ImageView01" android:layout_width="fill_parent" android:layout_height="fill_parent" android:adjustViewBounds="true" android:scaleType="centerInside" android:src="@drawable/splash" android:layout_gravity="center" /> </ScrollView> Splash is the image that is shown in the splash screen. I have those four folders with for storing drawables in my app: /res/drawable-hdpi /res/drawable-ldpi /res/drawable-mdpi /res/drawable-nodpi the splash image has its own version in the first three of them and is displayed properly. Removing the src property from the ImageView removes the image but not the exception. I'm a little bit lost with where to look for the cause of the exception. I even don't know if this is really an issue in this layout file etc. How would you go about finding the cause for this warning?

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• How to use NSMutableDictionary to store and retrieve data

  - by TechFusion

  I have created Window Based application and tab bar controller as root controller. My objective is to store Text Field data values in one tab bar VC and will be accessible and editable by other VC and also retrievable when application start. I am looking to use NSMutableDictionary class in AppDelegate so that I can access stored Data Values with keys. //TestAppDelegate.h extern NSString *kNamekey ; extern NSString *kUserIDkey ; extern NSString *kPasswordkey ; @interface TestAppDelegate :NSObject{ UIWindow *window; IBOutlet UITabBarController *rootController; NSMutableDictionary *outlineData ; } @property(nonatomic,retain)IBOutlet UIWindow *window; @property(nonatomic,retain)IBOutlet UITabBarController *rootController; @property(nonatomic,retain) NSMutableDictionary *outlineData ; @end //TestAppDelegate.m import "TestAppDelegate.h" NSString *kNamekey =@"Namekey"; NSString *kUserIDkey =@"UserIDkey"; NSString *kPasswordkey =@"Passwordkey"; @implemetation TestAppDelegate @synthesize outlineData ; -(void)applicationDidFinishLaunching:(UIApplication)application { NSMutableDictionary *tempMutableCopy = [[[NSUserDefaults standardUserDefaults] objectForKey:kRestoreLocationKey] mutableCopy]; self.outlineData = tempMutableCopy; [tempMutableCopy release]; if(outlineData == nil){ NSString *NameDefault = NULL; NSString *UserIDdefault= NULL; NSString *Passworddefault= NULL; NSMutableDictionary *appDefaults = [NSMutableDictionary dictionaryWithObjectsAndKeys: NameDefault, kNamekey , UserIDdefault, kUserIDkey , Passworddefault, kPasswordkey , nil]; self.outlineData = appDefaults; [appDefaults release]; } [window addSubview:rootController.view]; [window makeKeyAndVisible]; NSMutableDictionary *savedLocationDict = [NSMutableDictionary dictionaryWithObject:outlineData forKey:kRestoreLocationKey]; [[NSUserDefaults standardUserDefaults] registerDefaults:savedLocationDict]; [[NSUserDefaults standardUserDefaults] synchronize]; } -(void)applicationWillTerminate:(UIApplication *)application { [[NSUserDefaults standardUserDefaults] setObject:outlineData forKey:kRestoreLocationKey]; } @end Here ViewController is ViewController of Navigation Controller which is attached with one tab bar.. I have attached xib file with ViewController //ViewController.h @interface IBOutlet UITextField *Name; IBOutlet UITextField *UserId; IBOutlet UITextField *Password; } @property(retain,nonatomic) IBOutlet UITextField *Name @property(retain,nonatomic) IBOutlet UITextField *UserId; @property(retain,nonatomic) IBOutlet UITextField *Password; -(IBAction)Save:(id)sender; @end Here in ViewController.m, I am storing object values with keys. /ViewController.m -(IBAction)Save:(id)sender{ TestAppDelegate appDelegate = (TestAppDelegate)[[UIApplication sharedApplication] delegate]; [appDelegate.outlineData setObject:Name.text forKey:kNamekey ]; [appDelegate.outlineData setObject:UserId.text forKey:kUserIDkey ]; [appDelegate.outlineData setObject:Password.text forKey:kPasswordkey]; [[NSUserDefaults standardUserDefaults] synchronize]; } I am accessing stored object using following method. -(void)loadData { TabBarAppDelegate *appDelegate = (TabBarAppDelegate *)[[UIApplication sharedApplication] delegate]; Name = [appDelegate.outlineData objectForKey:kNamekey ]; UserId = [appDelegate.outlineData objectForKey:kUserIDkey ]; Password = [appDelegate.outlineData objectForKey:kPasswordkey]; [Name release]; [UserId release]; [Password release]; } I am getting EXEC_BAD_ACCESS in application. Where I am making mistake ? Thanks,

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• simple C++ hash_set example

  - by celil

  I am new to C++ and STL. I am stuck with the following simple example of a hash set storing custom data structures: #include <iostream> #include <ext/hash_set> using namespace std; using namespace __gnu_cxx; struct trip { int trip_id; int delta_n; int delta_secs; trip(int trip_id, int delta_n, int delta_secs){ this->trip_id = trip_id; this->delta_n = delta_n; this->delta_secs = delta_secs; } }; struct hash_trip { size_t operator()(const trip t) { hash<int> H; return H(t.trip_id); } }; struct eq_trip { bool operator()(const trip t1, const trip t2) { return (t1.trip_id==t2.trip_id) && (t1.delta_n==t2.delta_n) && (t1.delta_secs==t2.delta_secs); } }; int main() { hash_set<trip, hash_trip, eq_trip> trips; trip t = trip(3,2,-1); trip t1 = trip(3,2,0); trips.insert(t); } when I try to compile it, I get the following error message: /usr/include/c++/4.2.1/ext/hashtable.h: In member function ‘size_t __gnu_cxx::hashtable<_Val, _Key, _HashFcn, _ExtractKey, _EqualKey, _Alloc>::_M_bkt_num_key(const _Key&, size_t) const [with _Val = trip, _Key = trip, _HashFcn = hash_trip, _ExtractKey = std::_Identity<trip>, _EqualKey = eq_trip, _Alloc = std::allocator<trip>]’: /usr/include/c++/4.2.1/ext/hashtable.h:599: instantiated from ‘size_t __gnu_cxx::hashtable<_Val, _Key, _HashFcn, _ExtractKey, _EqualKey, _Alloc>::_M_bkt_num(const _Val&, size_t) const [with _Val = trip, _Key = trip, _HashFcn = hash_trip, _ExtractKey = std::_Identity<trip>, _EqualKey = eq_trip, _Alloc = std::allocator<trip>]’ /usr/include/c++/4.2.1/ext/hashtable.h:1006: instantiated from ‘void __gnu_cxx::hashtable<_Val, _Key, _HashFcn, _ExtractKey, _EqualKey, _Alloc>::resize(size_t) [with _Val = trip, _Key = trip, _HashFcn = hash_trip, _ExtractKey = std::_Identity<trip>, _EqualKey = eq_trip, _Alloc = std::allocator<trip>]’ /usr/include/c++/4.2.1/ext/hashtable.h:437: instantiated from ‘std::pair<__gnu_cxx::_Hashtable_iterator<_Val, _Key, _HashFcn, _ExtractKey, _EqualKey, _Alloc>, bool> __gnu_cxx::hashtable<_Val, _Key, _HashFcn, _ExtractKey, _EqualKey, _Alloc>::insert_unique(const _Val&) [with _Val = trip, _Key = trip, _HashFcn = hash_trip, _ExtractKey = std::_Identity<trip>, _EqualKey = eq_trip, _Alloc = std::allocator<trip>]’ /usr/include/c++/4.2.1/ext/hash_set:197: instantiated from ‘std::pair<typename __gnu_cxx::hashtable<_Value, _Value, _HashFcn, std::_Identity<_Value>, _EqualKey, _Alloc>::const_iterator, bool> __gnu_cxx::hash_set<_Value, _HashFcn, _EqualKey, _Alloc>::insert(const typename __gnu_cxx::hashtable<_Value, _Value, _HashFcn, std::_Identity<_Value>, _EqualKey, _Alloc>::value_type&) [with _Value = trip, _HashFcn = hash_trip, _EqualKey = eq_trip, _Alloc = std::allocator<trip>]’ try.cpp:45: instantiated from here /usr/include/c++/4.2.1/ext/hashtable.h:595: error: passing ‘const hash_trip’ as ‘this’ argument of ‘size_t hash_trip::operator()(trip)’ discards qualifiers What am I doing wrong?

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• Can't obtain reference to EKReminder array retrieved from fetchRemindersMatchingPredicate

  - by Scionwest

  When I create an NSPredicate via EKEventStore predicateForRemindersInCalendars; and pass it to EKEventStore fetchRemindersMatchingPredicate:completion:^ I can loop through the reminders array provided by the completion code block, but when I try to store a reference to the reminders array, or create a copy of the array into a local variable or instance variable, both array's remain empty. The reminders array is never copied to them. This is the method I am using, in the method, I create a predicate, pass it to the event store and then loop through all of the reminders logging their title via NSLog. I can see the reminder titles during runtime thanks to NSLog, but the local arrayOfReminders object is empty. I also try to add each reminder into an instance variable of NSMutableArray, but once I leave the completion code block, the instance variable remains empty. Am I missing something here? Can someone please tell me why I can't grab a reference to all of the reminders for use through-out the app? I am not having any issues at all accessing and storing EKEvents, but for some reason I can't do it with EKReminders. - (void)findAllReminders { NSPredicate *predicate = [self.eventStore predicateForRemindersInCalendars:nil]; __block NSArray *arrayOfReminders = [[NSArray alloc] init]; [self.eventStore fetchRemindersMatchingPredicate:predicate completion:^(NSArray *reminders) { arrayOfReminders = [reminders copy]; //Does not work. for (EKReminder *reminder in reminders) { [self.remindersForTheDay addObject:reminder]; NSLog(@"%@", reminder.title); } }]; //Always = 0; if ([self.remindersForTheDay count]) { NSLog(@"Instance Variable has reminders!"); } //Always = 0; if ([arrayOfReminders count]) { NSLog(@"Local Variable has reminders!"); } } The eventStore getter is where I perform my instantiation and get access to the event store. - (EKEventStore *)eventStore { if (!_eventStore) { _eventStore = [[EKEventStore alloc] init]; //respondsToSelector indicates iOS 6 support. if ([_eventStore respondsToSelector:@selector(requestAccessToEntityType:completion:)]) { //Request access to user calendar [_eventStore requestAccessToEntityType:EKEntityTypeEvent completion:^(BOOL granted, NSError *error) { if (granted) { NSLog(@"iOS 6+ Access to EventStore calendar granted."); } else { NSLog(@"Access to EventStore calendar denied."); } }]; //Request access to user Reminders [_eventStore requestAccessToEntityType:EKEntityTypeReminder completion:^(BOOL granted, NSError *error) { if (granted) { NSLog(@"iOS 6+ Access to EventStore Reminders granted."); } else { NSLog(@"Access to EventStore Reminders denied."); } }]; } else { //iOS 5.x and lower support if Selector is not supported NSLog(@"iOS 5.x < Access to EventStore calendar granted."); } for (EKCalendar *cal in self.calendars) { NSLog(@"Calendar found: %@", cal.title); } [_eventStore reset]; } return _eventStore; } Lastly, just to show that I am initializing my remindersForTheDay instance variable using lazy instantiation. - (NSMutableArray *)remindersForTheDay { if (!_remindersForTheDay) _remindersForTheDay = [[NSMutableArray alloc] init]; return _remindersForTheDay; } I've read through the Apple documentation and it doesn't provide any explanation that I can find to answer this. I read through the Blocks Programming docs and it states that you can access local and instance variables without issues from within a block, but for some reason, the above code does not work. Any help would be greatly appreciated, I've scoured Google for answers but have yet to get this figured out. Thanks everyone! Johnathon.

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• Exposing model object using bindings in custom NSCell of NSTableView

  - by Hooligancat

  I am struggling trying to perform what I would think would be a relatively common task. I have an NSTableView that is bound to it's array via an NSArrayController. The array controller has it's content set to an NSMutableArray that contains one or more NSObject instances of a model class. What I don't know how to do is expose the model inside the NSCell subclass in a way that is bindings friendly. For the purpose of illustration, we'll say that the object model is a person consisting of a first name, last name, age and gender. Thus the model would appear something like this: @interface PersonModel : NSObject { NSString * firstName; NSString * lastName; NSString * gender; int * age; } Obviously the appropriate setters, getters init etc for the class. In my controller class I define an NSTableView, NSMutableArray and an NSArrayController: @interface ControllerClass : NSObject { IBOutlet NSTableView * myTableView; NSMutableArray * myPersonArray; IBOutlet NSArrayController * myPersonArrayController; } Using Interface Builder I can easily bind the model to the appropriate columns: myPersonArray --> myPersonArrayController --> table column binding This works fine. So I remove the extra columns, leaving one column hidden that is bound to the NSArrayController (this creates and keeps the association between each row and the NSArrayController) so that I am down to one visible column in my NSTableView and one hidden column. I create an NSCell subclass and put the appropriate drawing method to create the cell. In my awakeFromNib I establish the custom NSCell subclass: PersonModel * aCustomCell = [[[PersonModel alloc] init] autorelease]; [[myTableView tableColumnWithIdentifier:@"customCellColumn"] setDataCell:aCustomCell]; This, too, works fine from a drawing perspective. I get my custom cell showing up in the column and it repeats for every managed object in my array controller. If I add an object or remove an object from the array controller the table updates accordingly. However... I was under the impression that my PersonModel object would be available from within my NSCell subclass. But I don't know how to get to it. I don't want to set each NSCell using setters and getters because then I'm breaking the whole model concept by storing data in the NSCell instead of referencing it from the array controller. And yes I do need to have a custom NSCell, so having multiple columns is not an option. Where to from here? In addition to the Google and StackOverflow search, I've done the obligatory walk through on Apple's docs and don't seem to have found the answer. I have found a lot of references that beat around the bush but nothing involving an NSArrayController. The controller makes life very easy when binding to other elements of the model entity (such as a master/detail scenario). I have also found a lot of references (although no answers) when using Core Data, but Im not using Core Data. As per the norm, I'm very grateful for any assistance that can be offered!

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• Loading a PyML multiclass classifier... why isn't this working?

  - by Michael Aaron Safyan

  This is a followup from "Save PyML.classifiers.multi.OneAgainstRest(SVM()) object?". I am using PyML for a computer vision project (pyimgattr), and have been having trouble storing/loading a multiclass classifier. When attempting to load one of the SVMs in a composite classifier, with loadSVM, I am getting: ValueError: invalid literal for float(): rest Note that this does not happen with the first classifier that I load, only with the second. What is causing this error, and what can I do to get around this so that I can properly load the classifier? Details To better understand the trouble I'm running into, you may want to look at pyimgattr.py (currently revision 11). I am invoking the program with "./pyimgattr.py train" which trains the classifier (invokes train on line 571, which trains the classifier with trainmulticlassclassifier on line 490 and saves it with storemulticlassclassifier on line 529), and then invoking the program with "./pyimgattr.py test" which loads the classifier in order to test it with the testing dataset (invokes test on line 628, which invokes loadmulticlassclassifier on line 549). The multiclass classifier consists of several one-against-rest SVMs which are saved individually. The loadmulticlassclassifier function loads these individually by calling loadSVM() on several different files. It is in this call to loadSVM (done indirectly in loadclassifier on line 517) that I get an error. The first of the one-against-rest classifiers loads successfully, but the second one does not. A transcript is as follows: $ ./pyimgattr.py test [INFO] pyimgattr -- Loading attributes from "classifiers/attributes.lst"... [INFO] pyimgattr -- Loading classnames from "classifiers/classnames.lst"... [INFO] pyimgattr -- Loading dataset "attribute_data/apascal_test.txt"... [INFO] pyimgattr -- Loaded dataset "attribute_data/apascal_test.txt". [INFO] pyimgattr -- Loading multiclass classifier from "classifiers/classnames_from_attributes"... [INFO] pyimgattr -- Constructing object into which to store loaded data... [INFO] pyimgattr -- Loading manifest data... [INFO] pyimgattr -- Loading classifier from "classifiers/classnames_from_attributes/aeroplane.svm".... scanned 100 patterns scanned 200 patterns read 100 patterns read 200 patterns {'50': 38, '60': 45, '61': 46, '62': 47, '49': 37, '52': 39, '53': 40, '24': 16, '25': 17, '26': 18, '27': 19, '20': 12, '21': 13, '22': 14, '23': 15, '46': 34, '47': 35, '28': 20, '29': 21, '40': 32, '41': 33, '1': 1, '0': 0, '3': 3, '2': 2, '5': 5, '4': 4, '7': 7, '6': 6, '8': 8, '58': 44, '39': 31, '38': 30, '15': 9, '48': 36, '16': 10, '19': 11, '32': 24, '31': 23, '30': 22, '37': 29, '36': 28, '35': 27, '34': 26, '33': 25, '55': 42, '54': 41, '57': 43} read 250 patterns in LinearSparseSVModel done LinearSparseSVModel constructed model [INFO] pyimgattr -- Loaded classifier from "classifiers/classnames_from_attributes/aeroplane.svm". [INFO] pyimgattr -- Loading classifier from "classifiers/classnames_from_attributes/bicycle.svm".... label at None delimiter , Traceback (most recent call last): File "./pyimgattr.py", line 797, in sys.exit(main(sys.argv)); File "./pyimgattr.py", line 782, in main return test(attributes_file,classnames_file,testing_annotations_file,testing_dataset_path,classifiers_path,logger); File "./pyimgattr.py", line 635, in test multiclass_classnames_from_attributes_classifier = loadmulticlassclassifier(classnames_from_attributes_folder,logger); File "./pyimgattr.py", line 529, in loadmulticlassclassifier classifiers.append(loadclassifier(os.path.join(filename,label+".svm"),logger)); File "./pyimgattr.py", line 502, in loadclassifier result=loadSVM(filename,datasetClass = SparseDataSet); File "/Library/Python/2.6/site-packages/PyML/classifiers/svm.py", line 328, in loadSVM data = datasetClass(fileName, **args) File "/Library/Python/2.6/site-packages/PyML/containers/vectorDatasets.py", line 224, in __init__ BaseVectorDataSet.__init__(self, arg, **args) File "/Library/Python/2.6/site-packages/PyML/containers/baseDatasets.py", line 214, in __init__ self.constructFromFile(arg, **args) File "/Library/Python/2.6/site-packages/PyML/containers/baseDatasets.py", line 243, in constructFromFile for x in parser : File "/Library/Python/2.6/site-packages/PyML/containers/parsers.py", line 426, in next x = [float(token) for token in tokens[self._first:self._last]] ValueError: invalid literal for float(): rest

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• Google App Engine - Secure Cookies

  - by tponthieux

  I'd been searching for a way to do cookie based authentication/sessions in Google App Engine because I don't like the idea of memcache based sessions, and I also don't like the idea of forcing users to create google accounts just to use a website. I stumbled across someone's posting that mentioned some signed cookie functions from the Tornado framework and it looks like what I need. What I have in mind is storing a user's id in a tamper proof cookie, and maybe using a decorator for the request handlers to test the authentication status of the user, and as a side benefit the user id will be available to the request handler for datastore work and such. The concept would be similar to forms authentication in ASP.NET. This code comes from the web.py module of the Tornado framework. According to the docstrings, it "Signs and timestamps a cookie so it cannot be forged" and "Returns the given signed cookie if it validates, or None." I've tried to use it in an App Engine Project, but I don't understand the nuances of trying to get these methods to work in the context of the request handler. Can someone show me the right way to do this without losing the functionality that the FriendFeed developers put into it? The set_secure_cookie, and get_secure_cookie portions are the most important, but it would be nice to be able to use the other methods as well. #!/usr/bin/env python import Cookie import base64 import time import hashlib import hmac import datetime import re import calendar import email.utils import logging def _utf8(s): if isinstance(s, unicode): return s.encode("utf-8") assert isinstance(s, str) return s def _unicode(s): if isinstance(s, str): try: return s.decode("utf-8") except UnicodeDecodeError: raise HTTPError(400, "Non-utf8 argument") assert isinstance(s, unicode) return s def _time_independent_equals(a, b): if len(a) != len(b): return False result = 0 for x, y in zip(a, b): result |= ord(x) ^ ord(y) return result == 0 def cookies(self): """A dictionary of Cookie.Morsel objects.""" if not hasattr(self,"_cookies"): self._cookies = Cookie.BaseCookie() if "Cookie" in self.request.headers: try: self._cookies.load(self.request.headers["Cookie"]) except: self.clear_all_cookies() return self._cookies def _cookie_signature(self,*parts): self.require_setting("cookie_secret","secure cookies") hash = hmac.new(self.application.settings["cookie_secret"], digestmod=hashlib.sha1) for part in parts:hash.update(part) return hash.hexdigest() def get_cookie(self,name,default=None): """Gets the value of the cookie with the given name,else default.""" if name in self.cookies: return self.cookies[name].value return default def set_cookie(self,name,value,domain=None,expires=None,path="/", expires_days=None): """Sets the given cookie name/value with the given options.""" name = _utf8(name) value = _utf8(value) if re.search(r"[\x00-\x20]",name + value): # Don't let us accidentally inject bad stuff raise ValueError("Invalid cookie %r:%r" % (name,value)) if not hasattr(self,"_new_cookies"): self._new_cookies = [] new_cookie = Cookie.BaseCookie() self._new_cookies.append(new_cookie) new_cookie[name] = value if domain: new_cookie[name]["domain"] = domain if expires_days is not None and not expires: expires = datetime.datetime.utcnow() + datetime.timedelta( days=expires_days) if expires: timestamp = calendar.timegm(expires.utctimetuple()) new_cookie[name]["expires"] = email.utils.formatdate( timestamp,localtime=False,usegmt=True) if path: new_cookie[name]["path"] = path def clear_cookie(self,name,path="/",domain=None): """Deletes the cookie with the given name.""" expires = datetime.datetime.utcnow() - datetime.timedelta(days=365) self.set_cookie(name,value="",path=path,expires=expires, domain=domain) def clear_all_cookies(self): """Deletes all the cookies the user sent with this request.""" for name in self.cookies.iterkeys(): self.clear_cookie(name) def set_secure_cookie(self,name,value,expires_days=30,**kwargs): """Signs and timestamps a cookie so it cannot be forged""" timestamp = str(int(time.time())) value = base64.b64encode(value) signature = self._cookie_signature(name,value,timestamp) value = "|".join([value,timestamp,signature]) self.set_cookie(name,value,expires_days=expires_days,**kwargs) def get_secure_cookie(self,name,include_name=True,value=None): """Returns the given signed cookie if it validates,or None""" if value is None:value = self.get_cookie(name) if not value:return None parts = value.split("|") if len(parts) != 3:return None if include_name: signature = self._cookie_signature(name,parts[0],parts[1]) else: signature = self._cookie_signature(parts[0],parts[1]) if not _time_independent_equals(parts[2],signature): logging.warning("Invalid cookie signature %r",value) return None timestamp = int(parts[1]) if timestamp < time.time() - 31 * 86400: logging.warning("Expired cookie %r",value) return None try: return base64.b64decode(parts[0]) except: return None uid=1234|1234567890|d32b9e9c67274fa062e2599fd659cc14 Parts: 1. uid is the name of the key 2. 1234 is your value in clear 3. 1234567890 is the timestamp 4. d32b9e9c67274fa062e2599fd659cc14 is the signature made from the value and the timestamp

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• Is SHA-1 secure for password storage?

  - by Tgr

  Some people throw around remarks like "SHA-1 is broken" a lot, so I'm trying to understand what exactly that means. Let's assume I have a database of SHA-1 password hashes, and an attacker whith a state of the art SHA-1 breaking algorithm and a botnet with 100,000 machines gets access to it. (Having control over 100k home computers would mean they can do about 10^15 operations per second.) How much time would they need to find out the password of any one user? find out the password of a given user? find out the password of all users? find a way to log in as one of the users? find a way to log in as a specific user? How does that change if the passwords are salted? Does the method of salting (prefix, postfix, both, or something more complicated like xor-ing) matter? Here is my current understanding, after some googling. Please correct in the answers if I misunderstood something. If there is no salt, a rainbow attack will immediately find all passwords (except extremely long ones). If there is a sufficiently long random salt, the most effective way to find out the passwords is a brute force or dictionary attack. Neither collision nor preimage attacks are any help in finding out the actual password, so cryptographic attacks against SHA-1 are no help here. It doesn't even matter much what algorithm is used - one could even use MD5 or MD4 and the passwords would be just as safe (there is a slight difference because computing a SHA-1 hash is slower). To evaluate how safe "just as safe" is, let's assume that a single sha1 run takes 1000 operations and passwords contain uppercase, lowercase and digits (that is, 60 characters). That means the attacker can test 1015*60*60*24 / 1000 ~= 1017 potential password a day. For a brute force attack, that would mean testing all passwords up to 9 characters in 3 hours, up to 10 characters in a week, up to 11 characters in a year. (It takes 60 times as much for every additional character.) A dictionary attack is much, much faster (even an attacker with a single computer could pull it off in hours), but only finds weak passwords. To log in as a user, the attacker does not need to find out the exact password; it is enough to find a string that results in the same hash. This is called a first preimage attack. As far as I could find, there are no preimage attacks against SHA-1. (A bruteforce attack would take 2160 operations, which means our theoretical attacker would need 1030 years to pull it off. Limits of theoretical possibility are around 260 operations, at which the attack would take a few years.) There are preimage attacks against reduced versions of SHA-1 with negligible effect (for the reduced SHA-1 which uses 44 steps instead of 80, attack time is down from 2160 operations to 2157). There are collision attacks against SHA-1 which are well within theoretical possibility (the best I found brings the time down from 280 to 252), but those are useless against password hashes, even without salting. In short, storing passwords with SHA-1 seems perfectly safe. Did I miss something?

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• How to implement an offline reader writer lock

  - by Peter Morris

  Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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• Optimal storage of data structure for fast lookup and persistence

  - by Mikael Svenson

  Scenario I have the following methods: public void AddItemSecurity(int itemId, int[] userIds) public int[] GetValidItemIds(int userId) Initially I'm thinking storage on the form: itemId -> userId, userId, userId and userId -> itemId, itemId, itemId AddItemSecurity is based on how I get data from a third party API, GetValidItemIds is how I want to use it at runtime. There are potentially 2000 users and 10 million items. Item id's are on the form: 2007123456, 2010001234 (10 digits where first four represent the year). AddItemSecurity does not have to perform super fast, but GetValidIds needs to be subsecond. Also, if there is an update on an existing itemId I need to remove that itemId for users no longer in the list. I'm trying to think about how I should store this in an optimal fashion. Preferably on disk (with caching), but I want the code maintainable and clean. If the item id's had started at 0, I thought about creating a byte array the length of MaxItemId / 8 for each user, and set a true/false bit if the item was present or not. That would limit the array length to little over 1mb per user and give fast lookups as well as an easy way to update the list per user. By persisting this as Memory Mapped Files with the .Net 4 framework I think I would get decent caching as well (if the machine has enough RAM) without implementing caching logic myself. Parsing the id, stripping out the year, and store an array per year could be a solution. The ItemId - UserId[] list can be serialized directly to disk and read/write with a normal FileStream in order to persist the list and diff it when there are changes. Each time a new user is added all the lists have to updated as well, but this can be done nightly. Question Should I continue to try out this approach, or are there other paths which should be explored as well? I'm thinking SQL server will not perform fast enough, and it would give an overhead (at least if it's hosted on a different server), but my assumptions might be wrong. Any thought or insights on the matter is appreciated. And I want to try to solve it without adding too much hardware :) [Update 2010-03-31] I have now tested with SQL server 2008 under the following conditions. Table with two columns (userid,itemid) both are Int Clustered index on the two columns Added ~800.000 items for 180 users - Total of 144 million rows Allocated 4gb ram for SQL server Dual Core 2.66ghz laptop SSD disk Use a SqlDataReader to read all itemid's into a List Loop over all users If I run one thread it averages on 0.2 seconds. When I add a second thread it goes up to 0.4 seconds, which is still ok. From there on the results are decreasing. Adding a third thread brings alot of the queries up to 2 seonds. A forth thread, up to 4 seconds, a fifth spikes some of the queries up to 50 seconds. The CPU is roofing while this is going on, even on one thread. My test app takes some due to the speedy loop, and sql the rest. Which leads me to the conclusion that it won't scale very well. At least not on my tested hardware. Are there ways to optimize the database, say storing an array of int's per user instead of one record per item. But this makes it harder to remove items.

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• Reading email address from contacts fails with weird memory issue - Solved

  - by CapsicumDreams

  Hi all, I'm stumped. I'm trying to get a list of all the email address a person has. I'm using the ABPeoplePickerNavigationController to select the person, which all seems fine. I'm setting my ABRecordRef personDealingWith; from the person argument to - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person property:(ABPropertyID)property identifier:(ABMultiValueIdentifier)identifier { and everything seems fine up till this point. The first time the following code executes, all is well. When subsequently run, I can get issues. First, the code: // following line seems to make the difference (issue 1) // NSLog(@"%d", ABMultiValueGetCount(ABRecordCopyValue(personDealingWith, kABPersonEmailProperty))); // construct array of emails ABMultiValueRef multi = ABRecordCopyValue(personDealingWith, kABPersonEmailProperty); CFIndex emailCount = ABMultiValueGetCount(multi); if (emailCount > 0) { // collect all emails in array for (CFIndex i = 0; i < emailCount; i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [emailArray addObject:(NSString *)emailRef]; CFRelease(emailRef); } } // following line also matters (issue 2) CFRelease(multi); If compiled as written, the are no errors or static analysis problems. This crashes with a *** -[Not A Type retain]: message sent to deallocated instance 0x4e9dc60 error. But wait, there's more! I can fix it in either of two ways. Firstly, I can uncomment the NSLog at the top of the function. I get a leak from the NSLog's ABRecordCopyValue every time through, but the code seems to run fine. Also, I can comment out the CFRelease(multi); at the end, which does exactly the same thing. Static compilation errors, but running code. So without a leak, this function crashes. To prevent a crash, I need to haemorrhage memory. Neither is a great solution. Can anyone point out what's going on? Solution: It turned out that I wasn't storing the ABRecordRef personDealingWith var correctly. I'm still not sure how to do that properly, but instead of having the functionality in another routine (performed later), I'm now doing the grunt-work in the delegate method, and using the derived results at my leisure. The new (working) routine: - (BOOL)peoplePickerNavigationController:(ABPeoplePickerNavigationController *)peoplePicker shouldContinueAfterSelectingPerson:(ABRecordRef)person { // as soon as they select someone, return personDealingWithFullName = (NSString *)ABRecordCopyCompositeName(person); personDealingWithFirstName = (NSString *)ABRecordCopyValue(person, kABPersonFirstNameProperty); // construct array of emails [personDealingWithEmails removeAllObjects]; ABMutableMultiValueRef multi = ABRecordCopyValue(person, kABPersonEmailProperty); if (ABMultiValueGetCount(multi) > 0) { // collect all emails in array for (CFIndex i = 0; i < ABMultiValueGetCount(multi); i++) { CFStringRef emailRef = ABMultiValueCopyValueAtIndex(multi, i); [personDealingWithEmails addObject:(NSString *)emailRef]; CFRelease(emailRef); } } CFRelease(multi); return NO; }

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• Temporary "Backup" of SharePoint Content During Feature and Solution Deployment

  - by ccomet

  I need to decide on a method for storing a subset of the content in a SharePoint site, so that when I delete and recreate certain lists as part of a feature activation, I can re-insert all of this content back where it should belong. I have an idea myself, but I don't know if it's the only method and more importantly, the right method. My client has me creating a SharePoint system for them to communicate with their clients. The business process has maybe 5 stages in it (maybe it's more, I don't even know because they don't tell me everything), and the current system I've written over the past months is maybe 2 stages through. This meets our deadline of completing those systems by Monday next week... but at that point my client is planning on making the site live from that point. In effect, their work with their clients will be running parallel with my work for them. As I complete my own work on a separate test server, I'll push each following stage of the process onto the live server. Scheduled downtimes during non-business times (like a weekend) will be available for me to perform these pushes. Keeping pace so that my development is faster than the actual business process is my own problem and off-topic... so let's get back to the problem I stated at the start of this post. In this system, we have sets of features which will create lists for their associated content types and field types when activated, and delete these lists when the feature is deactivated. Most updates don't need to deactivate and reactivate these features, such as workflow changes, custom actions, custom forms, and similar ilk. But there are some parts which do require this. On my test server, it's okay for me to obliterate lists, but once the site is live and there's real correspondence data, it's absolutely unacceptable to do this. So when I need to implement a new change in functionality, I need to be able to store the currently present data in several lists, deactivate the feature, reactivate the feature, and restore all of this data. Perhaps I have hoist myself by my own petard with the feature system I implemented. Unfortunately, the necessity to later on make several of these "project sites" meant I had to do a lot of my code with the concept of "Can be deployed repeatedly" in mind. My current plan is to run through lists and libraries which will be affected by the particular feature that is to be reset. Files and all of their versions will be saved in a directory on the server. Then, a set of text files will be used to store all of the important field values for the items. This includes a lot of cross-list reference lookups that will need to be maintained, but that's simple enough. Then, I deactivate the feature, deploy the new solution, and reactivate the feature. We upload all of the files in the order specified by their versions and update them with the stored fields for those versions, so that we retain the version structure. As each one is first uploaded, the new ID is picked out, and all relevant lookups in the rest of the files are updated (in some manner that I make sure I don't re-update it later with an incorrect value, of course). After that, we run through all the rest of the items in the order most conducive to keeping the relational data correct. This roughly summarizes what my current plan is. To my advantage, there are no long running workflows in the system that will be affected by this, so there's nothing I will have to worry about making sure nothing is "still running" when I do this stuff. I don't really know all the cons of this approach... I can imagine they're quite hefty. But I'm unsure what other choices I even have, and my searches haven't turned up anything. Is there anyone who can think of a better idea? Or will anyone just tell me that I really have no other choice? Thanks in advance!

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• Using AsyncTask to display data in ListView, but onPostExecute not being called

  - by sumisu

  I made a simple AsyncTask class to display data in ListView with the help of this stackoverflow question. But the AsyncTask onPostExecute is not being called. This is my code: public class Start extends SherlockActivity { // JSON Node names private static final String TAG_ID = "id"; private static final String TAG_NAME = "name"; // category JSONArray JSONArray category = null; private ListView lv; @Override public void onCreate(Bundle savedInstanceState) { setTheme(SampleList.THEME); //Used for theme switching in samples super.onCreate(savedInstanceState); setContentView(R.layout.test); new MyAsyncTask().execute("http://...."); // Launching new screen on Selecting Single ListItem lv.setOnItemClickListener(new OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // getting values from selected ListItem String name = ((TextView) view.findViewById(R.id.name)).getText().toString(); String cost = ((TextView) view.findViewById(R.id.mail)).getText().toString(); // Starting new intent Intent in = new Intent(getApplicationContext(), SingleMenuItemActivity.class); in.putExtra("categoryname", name); System.out.println(cost); in.putExtra("categoryid", cost); startActivity(in); } }); } public class MyAsyncTask extends AsyncTask<String, Void, ArrayList<HashMap<String, String>> > { // Hashmap for ListView ArrayList<HashMap<String, String>> contactList = new ArrayList<HashMap<String, String>>(); @Override protected ArrayList<HashMap<String, String>> doInBackground(String... params) { // Creating JSON Parser instance JSONParser jParser = new JSONParser(); // getting JSON string from URL category = jParser.getJSONArrayFromUrl(params[0]); try { // looping through All Contacts for(int i = 0; i < category.length(); i++){ JSONObject c = category.getJSONObject(i); // Storing each json item in variable String id = c.getString(TAG_ID); String name = c.getString(TAG_NAME); // creating new HashMap HashMap<String, String> map = new HashMap<String, String>(); // adding each child node to HashMap key => value map.put(TAG_ID, id); map.put(TAG_NAME, name); // adding HashList to ArrayList contactList.add(map); } } catch (JSONException e) { Log.e("log_tag", "Error parsing data "+e.toString()); } return contactList; } @Override protected void onPostExecute(ArrayList<HashMap<String, String>> result) { ListAdapter adapter = new SimpleAdapter(Start.this, result , R.layout.list_item, new String[] { TAG_NAME, TAG_ID }, new int[] { R.id.name, R.id.mail }); // selecting single ListView item lv = (ListView) findViewById(R.id.ListView); lv.setAdapter(adapter); } } } Eclipse: 11-25 11:40:31.896: E/AndroidRuntime(917): java.lang.RuntimeException: Unable to start activity ComponentInfo{de.essentials/de.main.Start}: java.lang.NullPointerException

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• Blackberry - application settings save/load

  - by Max Gontar

  Hi! I know two ways to save/load application settings: use PersistentStore use filesystem (store, since SDCard is optional) I'd like to know what are you're practicies of working with application settings? Using PersistentStore to save/load application settings The persistent store provides a means for objects to persist across device resets. A persistent object consists of a key-value pair. When a persistent object is committed to the persistent store, that object's value is stored in flash memory via a deep copy. The value can then be retrieved at a later point in time via the key. Example of helper class for storing and retrieving settings: class PSOptions { private PersistentObject mStore; private LongHashtableCollection mSettings; private long KEY_URL = 0; private long KEY_ENCRYPT = 1; private long KEY_REFRESH_PERIOD = 2; public PSOptions() { // "AppSettings" = 0x71f1f00b95850cfeL mStore = PersistentStore.getPersistentObject(0x71f1f00b95850cfeL); } public String getUrl() { Object result = get(KEY_URL); return (null != result) ? (String) result : null; } public void setUrl(String url) { set(KEY_URL, url); } public boolean getEncrypt() { Object result = get(KEY_ENCRYPT); return (null != result) ? ((Boolean) result).booleanValue() : false; } public void setEncrypt(boolean encrypt) { set(KEY_ENCRYPT, new Boolean(encrypt)); } public int getRefreshPeriod() { Object result = get(KEY_REFRESH_PERIOD); return (null != result) ? ((Integer) result).intValue() : -1; } public void setRefreshRate(int refreshRate) { set(KEY_REFRESH_PERIOD, new Integer(refreshRate)); } private void set(long key, Object value) { synchronized (mStore) { mSettings = (LongHashtableCollection) mStore.getContents(); if (null == mSettings) { mSettings = new LongHashtableCollection(); } mSettings.put(key, value); mStore.setContents(mSettings); mStore.commit(); } } private Object get(long key) { synchronized (mStore) { mSettings = (LongHashtableCollection) mStore.getContents(); if (null != mSettings && mSettings.size() != 0) { return mSettings.get(key); } else { return null; } } } } Example of use: class Scr extends MainScreen implements FieldChangeListener { PSOptions mOptions = new PSOptions(); BasicEditField mUrl = new BasicEditField("Url:", "http://stackoverflow.com/"); CheckboxField mEncrypt = new CheckboxField("Enable encrypt", false); GaugeField mRefresh = new GaugeField("Refresh period", 1, 60 * 10, 10, GaugeField.EDITABLE|FOCUSABLE); ButtonField mLoad = new ButtonField("Load settings", ButtonField.CONSUME_CLICK); ButtonField mSave = new ButtonField("Save settings", ButtonField.CONSUME_CLICK); public Scr() { add(mUrl); mUrl.setChangeListener(this); add(mEncrypt); mEncrypt.setChangeListener(this); add(mRefresh); mRefresh.setChangeListener(this); HorizontalFieldManager hfm = new HorizontalFieldManager(USE_ALL_WIDTH); add(hfm); hfm.add(mLoad); mLoad.setChangeListener(this); hfm.add(mSave); mSave.setChangeListener(this); loadSettings(); } public void fieldChanged(Field field, int context) { if (field == mLoad) { loadSettings(); } else if (field == mSave) { saveSettings(); } } private void saveSettings() { mOptions.setUrl(mUrl.getText()); mOptions.setEncrypt(mEncrypt.getChecked()); mOptions.setRefreshRate(mRefresh.getValue()); } private void loadSettings() { mUrl.setText(mOptions.getUrl()); mEncrypt.setChecked(mOptions.getEncrypt()); mRefresh.setValue(mOptions.getRefreshPeriod()); } }

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• Error data: line 2 column 1 when using pycurl with gzip stream

  - by Sagar Hatekar

  Thanks for reading. Background: I am trying to read a streaming API feed that returns data in JSON format, and then storing this data to a pymongo collection. The streaming API requires a "Accept-Encoding" : "Gzip" header. What's happening: Code fails on json.loads and outputs - Extra data: line 2 column 1 - line 4 column 1 (char 1891 - 5597) (Refer Error Log below) This does NOT happen while parsing every JSON object - it happens at random. My guess is I am encountering some weird JSON object after every "x" proper JSON objects. I did reference how to use pycurl if requested data is sometimes gzipped, sometimes not? and Encoding error while deserializing a json object from Google but so far have been unsuccessful at resolving this error. Could someone please help me out here? Error Log: Note: The raw dump of the JSON object below is basically using the repr() method. '{"id":"tag:search.twitter.com,2005:207958320747782146","objectType":"activity","actor":{"objectType":"person","id":"id:twitter.com:493653150","link":"http://www.twitter.com/Deathnews_7_24","displayName":"Death News 7/24","postedTime":"2012-02-16T01:30:12.000Z","image":"http://a0.twimg.com/profile_images/1834408513/deathnewstwittersquare_normal.jpg","summary":"Crashes, Murders, Suicides, Accidents, Crime and Naturals Death News From All Around World","links":[{"href":"http://www.facebook.com/DeathNews724","rel":"me"}],"friendsCount":56,"followersCount":14,"listedCount":1,"statusesCount":1029,"twitterTimeZone":null,"utcOffset":null,"preferredUsername":"Deathnews_7_24","languages":["tr"]},"verb":"post","postedTime":"2012-05-30T22:15:02.000Z","generator":{"displayName":"web","link":"http://twitter.com"},"provider":{"objectType":"service","displayName":"Twitter","link":"http://www.twitter.com"},"link":"http://twitter.com/Deathnews_7_24/statuses/207958320747782146","body":"Kathi Kamen Goldmark, Writers\xe2\x80\x99 Catalyst, Dies at 63 http://t.co/WBsNlNtA","object":{"objectType":"note","id":"object:search.twitter.com,2005:207958320747782146","summary":"Kathi Kamen Goldmark, Writers\xe2\x80\x99 Catalyst, Dies at 63 http://t.co/WBsNlNtA","link":"http://twitter.com/Deathnews_7_24/statuses/207958320747782146","postedTime":"2012-05-30T22:15:02.000Z"},"twitter_entities":{"urls":[{"display_url":"nytimes.com/2012/05/30/boo\xe2\x80\xa6","indices":[52,72],"expanded_url":"http://www.nytimes.com/2012/05/30/books/kathi-kamen-goldmark-writers-catalyst-dies-at-63.html","url":"http://t.co/WBsNlNtA"}],"hashtags":[],"user_mentions":[]},"gnip":{"language":{"value":"en"},"matching_rules":[{"value":"url_contains: nytimes.com","tag":null}],"klout_score":11,"urls":[{"url":"http://t.co/WBsNlNtA","expanded_url":"http://www.nytimes.com/2012/05/30/books/kathi-kamen-goldmark-writers-catalyst-dies-at-63.html?_r=1"}]}}\r\n{"id":"tag:search.twitter.com,2005:207958321003638785","objectType":"activity","actor":{"objectType":"person","id":"id:twitter.com:178760897","link":"http://www.twitter.com/Mobanu","displayName":"Donald Ochs","postedTime":"2010-08-15T16:33:56.000Z","image":"http://a0.twimg.com/profile_images/1493224811/small_mobany_Logo_normal.jpg","summary":"","links":[{"href":"http://www.mobanuweightloss.com","rel":"me"}],"friendsCount":10272,"followersCount":9698,"listedCount":30,"statusesCount":725,"twitterTimeZone":"Mountain Time (US & Canada)","utcOffset":"-25200","preferredUsername":"Mobanu","languages":["en"],"location":{"objectType":"place","displayName":"Crested Butte, Colorado"}},"verb":"post","postedTime":"2012-05-30T22:15:02.000Z","generator":{"displayName":"twitterfeed","link":"http://twitterfeed.com"},"provider":{"objectType":"service","displayName":"Twitter","link":"http://www.twitter.com"},"link":"http://twitter.com/Mobanu/statuses/207958321003638785","body":"Mobanu: Can Exercise Be Bad for You?: Researchers have found evidence that some people who exercise do worse on ... http://t.co/mTsQlNQO","object":{"objectType":"note","id":"object:search.twitter.com,2005:207958321003638785","summary":"Mobanu: Can Exercise Be Bad for You?: Researchers have found evidence that some people who exercise do worse on ... http://t.co/mTsQlNQO","link":"http://twitter.com/Mobanu/statuses/207958321003638785","postedTime":"2012-05-30T22:15:02.000Z"},"twitter_entities":{"urls":[{"display_url":"nyti.ms/KUmmMa","indices":[116,136],"expanded_url":"http://nyti.ms/KUmmMa","url":"http://t.co/mTsQlNQO"}],"hashtags":[],"user_mentions":[]},"gnip":{"language":{"value":"en"},"matching_rules":[{"value":"url_contains: nytimes.com","tag":null}],"klout_score":12,"urls":[{"url":"http://t.co/mTsQlNQO","expanded_url":"http://well.blogs.nytimes.com/2012/05/30/can-exercise-be-bad-for-you/?utm_medium=twitter&utm_source=twitterfeed"}]}}\r\n' json exception: Extra data: line 2 column 1 - line 4 column 1 (char 1891 - 5597) Header Output: HTTP/1.1 200 OK Content-Type: application/json; charset=UTF-8 Vary: Accept-Encoding Date: Wed, 30 May 2012 22:14:48 UTC Connection: close Transfer-Encoding: chunked Content-Encoding: gzip get_stream.py: #!/usr/bin/env python import sys import pycurl import json import pymongo STREAM_URL = "https://stream.test.com:443/accounts/publishers/twitter/streams/track/Dev.json" AUTH = "userid:passwd" DB_HOST = "127.0.0.1" DB_NAME = "stream_test" class StreamReader: def __init__(self): try: self.count = 0 self.buff = "" self.mongo = pymongo.Connection(DB_HOST) self.db = self.mongo[DB_NAME] self.raw_tweets = self.db["raw_tweets_gnip"] self.conn = pycurl.Curl() self.conn.setopt(pycurl.ENCODING, 'gzip') self.conn.setopt(pycurl.URL, STREAM_URL) self.conn.setopt(pycurl.USERPWD, AUTH) self.conn.setopt(pycurl.WRITEFUNCTION, self.on_receive) self.conn.setopt(pycurl.HEADERFUNCTION, self.header_rcvd) while True: self.conn.perform() except Exception as ex: print "error ocurred : %s" % str(ex) def header_rcvd(self, header_data): print header_data def on_receive(self, data): temp_data = data self.buff += data if data.endswith("\r\n") and self.buff.strip(): try: tweet = json.loads(self.buff, encoding = 'UTF-8') self.buff = "" if tweet: try: self.raw_tweets.insert(tweet) except Exception as insert_ex: print "Error inserting tweet: %s" % str(insert_ex) self.count += 1 if self.count % 10 == 0: print "inserted "+str(self.count)+" tweets" except Exception as json_ex: print "json exception: %s" % str(json_ex) print repr(temp_data) stream = StreamReader()

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• Python: Memory usage and optimization when modifying lists

  - by xApple

  The problem My concern is the following: I am storing a relativity large dataset in a classical python list and in order to process the data I must iterate over the list several times, perform some operations on the elements, and often pop an item out of the list. It seems that deleting one item out of a Python list costs O(N) since Python has to copy all the items above the element at hand down one place. Furthermore, since the number of items to delete is approximately proportional to the number of elements in the list this results in an O(N^2) algorithm. I am hoping to find a solution that is cost effective (time and memory-wise). I have studied what I could find on the internet and have summarized my different options below. Which one is the best candidate ? Keeping a local index: while processingdata: index = 0 while index < len(somelist): item = somelist[index] dosomestuff(item) if somecondition(item): del somelist[index] else: index += 1 This is the original solution I came up with. Not only is this not very elegant, but I am hoping there is better way to do it that remains time and memory efficient. Walking the list backwards: while processingdata: for i in xrange(len(somelist) - 1, -1, -1): dosomestuff(item) if somecondition(somelist, i): somelist.pop(i) This avoids incrementing an index variable but ultimately has the same cost as the original version. It also breaks the logic of dosomestuff(item) that wishes to process them in the same order as they appear in the original list. Making a new list: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) newlist = [] for item in somelist: if somecondition(item): newlist.append(item) somelist = newlist gc.collect() This is a very naive strategy for eliminating elements from a list and requires lots of memory since an almost full copy of the list must be made. Using list comprehensions: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist[:] = [x for x in somelist if somecondition(x)] This is very elegant but under-the-cover it walks the whole list one more time and must copy most of the elements in it. My intuition is that this operation probably costs more than the original del statement at least memory wise. Keep in mind that somelist can be huge and that any solution that will iterate through it only once per run will probably always win. Using the filter function: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist = filter(lambda x: not subtle_condition(x), somelist) This also creates a new list occupying lots of RAM. Using the itertools' filter function: from itertools import ifilterfalse while processingdata: for item in itertools.ifilterfalse(somecondtion, somelist): dosomestuff(item) This version of the filter call does not create a new list but will not call dosomestuff on every item breaking the logic of the algorithm. I am including this example only for the purpose of creating an exhaustive list. Moving items up the list while walking while processingdata: index = 0 for item in somelist: dosomestuff(item) if not somecondition(item): somelist[index] = item index += 1 del somelist[index:] This is a subtle method that seems cost effective. I think it will move each item (or the pointer to each item ?) exactly once resulting in an O(N) algorithm. Finally, I hope Python will be intelligent enough to resize the list at the end without allocating memory for a new copy of the list. Not sure though. Abandoning Python lists: class Doubly_Linked_List: def __init__(self): self.first = None self.last = None self.n = 0 def __len__(self): return self.n def __iter__(self): return DLLIter(self) def iterator(self): return self.__iter__() def append(self, x): x = DLLElement(x) x.next = None if self.last is None: x.prev = None self.last = x self.first = x self.n = 1 else: x.prev = self.last x.prev.next = x self.last = x self.n += 1 class DLLElement: def __init__(self, x): self.next = None self.data = x self.prev = None class DLLIter: etc... This type of object resembles a python list in a limited way. However, deletion of an element is guaranteed O(1). I would not like to go here since this would require massive amounts of code refactoring almost everywhere.

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