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• MSDN Remark regards Security Descriptors

  - by Doori Bar

  I'm trying to extract and restore a Security Descriptor of a NTFS file, via Windows API - XP SP3, I'm trying to understand which functions are actually able to do it properly, but I simply fail. I found this Remark over MSDN: http://msdn.microsoft.com/en-us/library/aa379573%28VS.85%29.aspx "Some SECURITY_INFORMATION members work only with the SetNamedSecurityInfo function. These members are not returned in the structure returned by other security functions such as GetNamedSecurityInfo..." "Some members..." Which members? Why? "Other Security functions such as..." Which functions? Why? Anybody have any experience with extracting and restoring a security descriptor of a NTFS file? Thanks in advance, Doori Bar

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• Open SSL without SHA1

  - by Hellnar

  Is there any way to use Open SSL without any SHA1 hash functions and using one of SHA2 functions instead of it? I think firstly, I should find all the functions that call SHA1 algorithm, and I should understand why SHA1 is still used. While changing the hash function, the bits are different in SHA1 and SHA2 so it may cause some problems. It confuses me...

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• Hook into a unknown function in a dll using C#

  - by John ClearZ

  Is it possible to find out what functions are available in an arbitrary dll file and then call these functions using C# interop services.

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• Getting the callers of a specific function

  - by robUK

  Hello, GNU Emacs 23.1.1 I am just wondering is there any feature in emacs where I can find out what functions call a specific function. In my code, I normally have to do a search on the function name to see what functions calls it. It would be nice if I could display all the names of the functions where this specific function is being called from. many thanks for any suggestions,

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• Using the same variable across multiple files in C++

  - by Sam152

  In the process of changing some code, I have spilt some functions into multiple files. I have the files controls.cpp and display.cpp and I would like to be able to have access to the same set of variables in both files. I don't mind where they are initialized or declared, as long as the functions in both files can use them. This was not an issue when the functions were in the same file, but now it seems almost impossible after an hour of googling and trying various things.

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• How to avoid circular reference when excel cell update

  - by Nimo

  Hi, I'm writing a set of functions in c++ which can be called by excel. However, these functions are asynchronous, therefore no immediate return values available. Once a result is available I used a callback function through VBA which update the result to the relevant cell which called the functions. But, here I'm having circular function calling problem, because when I update the cell. excel automatically call the original function once again. Please help me to get around this problem Thank You

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• C# 4.0 how to pass variables to threads?

  - by Aviatrix

  How would i pass some parameters to a new thread that runs a function from another class ? What i'm trying to do is to pass an array or multiple variables to a function that sits in another class and its called by a new thread. i have tried to do it like this Functions functions = new Functions(); string[] data; Thread th = new Thread(new ParameterizedThreadStart(functions.Post())); th.Start(data); but it shows error "No overload for method 'Post' takes 0 arguments" Any ideas ?

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• what is the difference between round() & trunc() function?

  - by paddu

  I am very confused about these functions?

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• Hibernate. 2 functions : simpleSave() , saveWithCascade() . can it be done ? and how ?

  - by Blitzkr1eg

  I have a scenario in which i have: A parent class Parent which has some simple properties (int, String, etc) and 2 set of children. Set childrenA; Set childrenB; Could i make a save function for parent simpleSave(Parent p) that will save/persists only the parent properties in the database and have a function saveWithCascade(Parent p) that will cascade to its children ?

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• How to tell if SPARC T4 crypto is being used?

  - by danx

  A question that often comes up when running applications on SPARC T4 systems is "How can I tell if hardware crypto accleration is being used?" To review, the SPARC T4 processor includes a crypto unit that supports several crypto instructions. For hardware crypto these include 11 AES instructions, 4 xmul* instructions (for AES GCM carryless multiply), mont for Montgomery multiply (optimizes RSA and DSA), and 5 des_* instructions (for DES3). For hardware hash algorithm optimization, the T4 has the md5, sha1, sha256, and sha512 instructions (the last two are used for SHA-224 an SHA-384). First off, it's easy to tell if the processor T4 crypto instructions—use the isainfo -v command and look for "sparcv9" and "aes" (and other hash and crypto algorithms) in the output: $ isainfo -v 64-bit sparcv9 applications crc32c cbcond pause mont mpmul sha512 sha256 sha1 md5 camellia kasumi des aes ima hpc vis3 fmaf asi_blk_init vis2 vis popc These instructions are not-privileged, so are available for direct use in user-level applications and libraries (such as OpenSSL). Here is the "openssl speed -evp" command shown with the built-in t4 engine and with the pkcs11 engine. Both run the T4 AES instructions, but the t4 engine is faster than the pkcs11 engine because it has less overhead (especially for smaller packet sizes): t-4 $ /usr/bin/openssl version OpenSSL 1.0.0j 10 May 2012 t-4 $ /usr/bin/openssl engine (t4) SPARC T4 engine support (dynamic) Dynamic engine loading support (pkcs11) PKCS #11 engine support t-4 $ /usr/bin/openssl speed -evp aes-128-cbc # t4 engine used by default . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 487777.10k 816822.21k 986012.59k 1017029.97k 1053543.08k t-4 $ /usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc engine "pkcs11" set. . . . The 'numbers' are in 1000s of bytes per second processed. type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes aes-128-cbc 31703.58k 116636.39k 350672.81k 696170.50k 993599.49k Note: The "-evp" flag indicates use the OpenSSL "EnVeloPe" API, which gives more accurate results. That's because it tells OpenSSL to use the same API that external programs use when calling OpenSSL libcrypto functions, evp(3openssl). DTrace Shows if T4 Crypto Functions Are Used OK, good enough, the isainfo(1) command shows the instructions are present, but how does one know if they are being used? Chi-Chang Lin, who works on Oracle Solaris performance, wrote a Dtrace script to show if T4 instructions are being executed. To show the T4 instructions are being used, run the following Dtrace script. Look for functions named "t4" and "yf" in the output. The OpenSSL T4 engine uses functions named "t4" and the PKCS#11 engine uses functions named "yf". To demonstrate, I'll first run "openssl speed" with the built-in t4 engine then with the pkcs11 engine. The performance numbers are not valid due to dtrace probes slowing things down. t-4 # dtrace -Z -n ' pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes . . . dtrace: pid 2029 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_init 1 libcrypto.so.1.0.0 t4_add_NID 3 libcrypto.so.1.0.0 t4_aes_expand128 5 libcrypto.so.1.0.0 t4_cipher_init_aes 5 libcrypto.so.1.0.0 t4_get_all_ciphers 6 libcrypto.so.1.0.0 t4_get_all_digests 59 libcrypto.so.1.0.0 t4_digest_final_sha1 65 libcrypto.so.1.0.0 t4_digest_init_sha1 65 libcrypto.so.1.0.0 t4_sha1_multiblock 126 libcrypto.so.1.0.0 t4_digest_update_sha1 261 libcrypto.so.1.0.0 t4_aes128_cbc_encrypt 1432979 libcrypto.so.1.0.0 t4_aes128_load_keys_for_encrypt 1432979 libcrypto.so.1.0.0 t4_cipher_do_aes_128_cbc 1432979 t-4 # dtrace -Z -n 'pid$target::*yf*:entry{ @[probemod, probefunc] = count();}   pid$target::*yf*:entry,pid$target::*t4_*:entry{ @[probemod, probefunc] = count();}' \ -c "/usr/bin/openssl speed -engine pkcs11 -evp aes-128-cbc" dtrace: description 'pid$target::*yf*:entry' matched 101 probes engine "pkcs11" set. . . . dtrace: pid 2033 has exited libcrypto.so.1.0.0 ENGINE_load_t4 1 libcrypto.so.1.0.0 t4_DH 1 libcrypto.so.1.0.0 t4_DSA 1 libcrypto.so.1.0.0 t4_RSA 1 libcrypto.so.1.0.0 t4_destroy 1 libcrypto.so.1.0.0 t4_free_aes_ctr_NIDs 1 libcrypto.so.1.0.0 t4_get_all_ciphers 1 libcrypto.so.1.0.0 t4_get_all_digests 1 libsoftcrypto.so.1 rijndael_key_setup_enc_yf 1 libsoftcrypto.so.1 yf_aes_expand128 1 libcrypto.so.1.0.0 t4_add_NID 3 libsoftcrypto.so.1 yf_aes128_cbc_encrypt 1542330 libsoftcrypto.so.1 yf_aes128_load_keys_for_encrypt 1542330 So, as shown above the OpenSSL built-in t4 engine executes t4_* functions (which are hand-coded assembly executing the T4 AES instructions) and the OpenSSL pkcs11 engine executes *yf* functions. Programmatic Use of OpenSSL T4 engine The OpenSSL t4 engine is used automatically with the /usr/bin/openssl command line. Chi-Chang Lin also points out that if you're calling the OpenSSL API (libcrypto.so) from a program, you must call ENGINE_load_built_engines(), otherwise the built-in t4 engine will not be loaded. You do not call ENGINE_set_default(). That's because "openssl speed -evp" test calls ENGINE_load_built_engines() even though the "-engine" option wasn't specified. OpenSSL T4 engine Availability The OpenSSL t4 engine is available with Solaris 11 and 11.1. For Solaris 10 08/11 (U10), you need to use the OpenSSL pkcs311 engine. The OpenSSL t4 engine is distributed only with the version of OpenSSL distributed with Solaris (and not third-party or self-compiled versions of OpenSSL). The OpenSSL engine implements the AES cipher for Solaris 11, released 11/2011. For Solaris 11.1, released 11/2012, the OpenSSL engine adds optimization for the MD5, SHA-1, and SHA-2 hash algorithms, and DES-3. Although the T4 processor has Camillia and Kasumi block cipher instructions, these are not implemented in the OpenSSL T4 engine. The following charts may help view availability of optimizations. The first chart shows what's available with Solaris CLIs and APIs, the second chart shows what's available in Solaris OpenSSL. Native Solaris Optimization for SPARC T4 This table is shows Solaris native CLI and API support. As such, they are all available with the OpenSSL pkcs11 engine. CLIs: "openssl -engine pkcs11", encrypt(1), decrypt(1), mac(1), digest(1), MD5sum(1), SHA1sum(1), SHA224sum(1), SHA256sum(1), SHA384sum(1), SHA512sum(1) APIs: PKCS#11 library libpkcs11(3LIB) (incluDES Openssl pkcs11 engine), libMD(3LIB), and Solaris kernel modules AlgorithmSolaris 1008/11 (U10)Solaris 11Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES2-ECB, DES2-CBC, DES-ECB, DES-CBC XXX bignum Montgomery multiply (RSA, DSA) XXX MD5, SHA-1, SHA-256, SHA-384, SHA-512 XXX SHA-224 X ARCFOUR (RC4) X Solaris OpenSSL T4 Engine Optimization This table is for the Solaris OpenSSL built-in t4 engine. Algorithms listed above are also available through the OpenSSL pkcs11 engine. CLI: openssl(1openssl) APIs: openssl(5), engine(3openssl), evp(3openssl), libcrypto crypto(3openssl) AlgorithmSolaris 11Solaris 11SRU2Solaris 11.1 AES-ECB, AES-CBC, AES-CTR, AES-CBC AES-CFB128 XXX DES3-ECB, DES3-CBC, DES-ECB, DES-CBC X bignum Montgomery multiply (RSA, DSA) X MD5, SHA-1, SHA-256, SHA-384, SHA-512 XX SHA-224 X Source Code Availability Solaris Most of the T4 assembly code that called the new T4 crypto instructions was written by Ferenc Rákóczi of the Solaris Security group, with assistance from others. You can download the Solaris source for this and other parts of Solaris as a few zip files at the Oracle Download website. The relevant source files are generally under directories usr/src/common/crypto/{aes,arcfour,des,md5,modes,sha1,sha2}}/sun4v/. and usr/src/common/bignum/sun4v/. Solaris 11 binary is available from the Oracle Solaris 11 download website. OpenSSL t4 engine The source for the OpenSSL t4 engine, which is based on the Solaris source above, is viewable through the OpenGrok source code browser in directory src/components/openssl/openssl-1.0.0/engines/t4 . You can download the source from the same website or through Mercurial source code management, hg(1). Conclusion Oracle Solaris with SPARC T4 provides a rich set of accelerated cryptographic and hash algorithms. Using the latest update, Solaris 11.1, provides the best set of optimized algorithms, but alternatives are often available, sometimes slightly slower, for releases back to Solaris 10 08/11 (U10). Reference See also these earlier blogs. SPARC T4 OpenSSL Engine by myself, Dan Anderson (2011), discusses the Openssl T4 engine and reviews the SPARC T4 processor for the Solaris 11 release. Exciting Crypto Advances with the T4 processor and Oracle Solaris 11 by Valerie Fenwick (2011) discusses crypto algorithms that were optimized for the T4 processor with the Solaris 11 FCS (11/11) and Solaris 10 08/11 (U10) release. T4 Crypto Cheat Sheet by Stefan Hinker (2012) discusses how to make T4 crypto optimization available to various consumers (such as SSH, Java, OpenSSL, Apache, etc.) High Performance Security For Oracle Database and Fusion Middleware Applications using SPARC T4 (PDF, 2012) discusses SPARC T4 and its usage to optimize application security. Configuring Oracle iPlanet WebServer / Oracle Traffic Director to use crypto accelerators on T4-1 servers by Meena Vyas (2012)

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• SQL SERVER – Weekly Series – Memory Lane – #007

  - by pinaldave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Find Stored Procedure Related to Table in Database – Search in All Stored Procedure In 2006 I wrote a small script which will help user  find all the Stored Procedures (SP) which are related to one or more specific tables. This was quite a popular script however, in SQL Server 2012 the same can be achieved using new DMV sys.sql-expression_dependencies. I recently blogged about it over Find Referenced or Referencing Object in SQL Server using sys.sql_expression_dependencies. 2007 SQL SERVER – Versions, CodeNames, Year of Release 1993 – SQL Server 4.21 for Windows NT 1995 – SQL Server 6.0, codenamed SQL95 1996 – SQL Server 6.5, codenamed Hydra 1999 – SQL Server 7.0, codenamed Sphinx 1999 – SQL Server 7.0 OLAP, codenamed Plato 2000 – SQL Server 2000 32-bit, codenamed Shiloh (version 8.0) 2003 – SQL Server 2000 64-bit, codenamed Liberty 2005 – SQL Server 2005, codenamed Yukon (version 9.0) 2008 – SQL Server 2008, codenamed Katmai (version 10.0) 2011 – SQL Server 2008, codenamed Denali (version 11.0) Search String in Stored Procedure Searching sting in the stored procedure is one of the most frequent task developer do. They might be searching for a table, view or any other details. I have written a script to do the same in SQL Server 2000 and SQL Server 2005. This is worth bookmarking blog post. There is an alternative way to do the same as well here is the example. 2008 SQL SERVER – Refresh Database Using T-SQL NO! Some of the questions have a single answer NO! You may want to read the question in the original blog post. I had a great time saying No! SQL SERVER – Delete Backup History – Cleanup Backup History SQL Server stores history of all the taken backup forever. History of all the backup is stored in the msdb database. Many times older history is no more required. Following Stored Procedure can be executed with a parameter which takes days of history to keep. In the following example 30 is passed to keep a history of month. 2009 Stored Procedure are Compiled on First Run – SP taking Longer to Run First Time Is stored procedure pre-compiled? Why the Stored Procedure takes a long time to run for the first time?  This is a very common questions often discussed by developers and DBAs. There is an absolutely definite answer but the question has been discussed forever. There is a misconception that stored procedures are pre-compiled. They are not pre-compiled, but compiled only during the first run. For every subsequent runs, it is for sure pre-compiled. Read the entire article for example and demonstration. Removing Key Lookup – Seek Predicate – Predicate – An Interesting Observation Related to Datatypes This is one of the most important performance tuning lesson on my blog. I suggest this weekend you spend time reading them and let me know what you think about the concepts which I have demonstrated in the four part series. Part 1 | Part 2 | Part 3 | Part 4 Seek Predicate is the operation that describes the b-tree portion of the Seek. Predicate is the operation that describes the additional filter using non-key columns. Based on the description, it is very clear that Seek Predicate is better than Predicate as it searches indexes whereas in Predicate, the search is on non-key columns – which implies that the search is on the data in page files itself. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL Server – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administration assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. 2010 Recycle Error Log – Create New Log file without Server Restart Once I observed a DBA to restaring the SQL Server when he needed new error log file. This was funny and sad both at the same time. There is no need to restart the server to create a new log file or recycle the log file. You can run sp_cycle_errorlog and achieve the same result. Get Database Backup History for a Single Database Simple but effective script! Reducing CXPACKET Wait Stats for High Transactional Database The subject is very complex and I have done my best to simplify the concept. In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Information Related to DATETIME and DATETIME2 There are quite a lot of confusion with DATETIME and DATETIME2. DATETIME2 is also one of the underutilized datatype of SQL Server.  In this blog post I have written a follow up of the my earlier datetime series where I clarify a few of the concepts related to datetime. Difference Between GETDATE and SYSDATETIME Difference Between DATETIME and DATETIME2 – WITH GETDATE Difference Between DATETIME and DATETIME2 2011 Introduction to CUME_DIST – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function CUME_DIST(). This function provides cumulative distribution value. It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Introduction to FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical functions FIRST_VALUE() and LAST_VALUE(). This function returns first and last value from the list. It will be very difficult to explain this in words so I’d like to attempt to explain its function through a brief example. Instead of creating a new table, I will be using the AdventureWorks sample database as most developers use that for experiment purposes. OVER clause with FIRST _VALUE and LAST_VALUE – Analytic Functions Introduced in SQL Server 2012 – ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING “Don’t you think there is bug in your first example where FIRST_VALUE is remain same but the LAST_VALUE is changing every line. I think the LAST_VALUE should be the highest value in the windows or set of result.” Puzzle – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY You can see that row number 2, 3, 4, and 5 has same SalesOrderID = 43667. The FIRST_VALUE is 78 and LAST_VALUE is 77. Now if these function was working on maximum and minimum value they should have given answer as 77 and 80 respectively instead of 78 and 77. Also the value of FIRST_VALUE is greater than LAST_VALUE 77. Why? Explain in detail. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available Our book was out of stock in 48 hours of it was arrived in stock! We got call from the online store with a request for more copies within 12 hours. But we had printed only as many as we had sent them. There were no extra copies. We finally talked to the printer to get more copies. However, due to festivals and holidays the copies could not be shipped to the online retailer for two days. We knew for sure that they were going to be out of the book for 48 hours. This is the story of how we overcame that situation! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Red Hat Yum not working out of the box?

  - by Tucker

  I have a server runnning Red Hat Enterprise Linux v5.6 in the cloud. My project constraints do not allow me to use another OS. When I created the cloud server, I was able to SSH into it and access the shell. I next ran the command: sudo yum update But the command failed. About a month ago I created another server with the same machine image and didn't have that error. Why is it failing now? The following is the terminal output sudo yum update Loaded plugins: security Repository rhel-server is listed more than once in the configuration Traceback (most recent call last): File "/usr/bin/yum", line 29, in ? yummain.user_main(sys.argv[1:], exit_code=True) File "/usr/share/yum-cli/yummain.py", line 309, in user_main errcode = main(args) File "/usr/share/yum-cli/yummain.py", line 178, in main result, resultmsgs = base.doCommands() File "/usr/share/yum-cli/cli.py", line 345, in doCommands self._getTs(needTsRemove) File "/usr/lib/python2.4/site-packages/yum/depsolve.py", line 101, in _getTs self._getTsInfo(remove_only) File "/usr/lib/python2.4/site-packages/yum/depsolve.py", line 112, in _getTsInfo pkgSack = self.pkgSack File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 662, in <lambda> pkgSack = property(fget=lambda self: self._getSacks(), File "/usr/lib/python2.4/site-packages/yum/__init__.py", line 502, in _getSacks self.repos.populateSack(which=repos) File "/usr/lib/python2.4/site-packages/yum/repos.py", line 260, in populateSack sack.populate(repo, mdtype, callback, cacheonly) File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 168, in populate if self._check_db_version(repo, mydbtype): File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 226, in _check_db_version return repo._check_db_version(mdtype) File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1233, in _check_db_version repoXML = self.repoXML File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1406, in <lambda> repoXML = property(fget=lambda self: self._getRepoXML(), File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1398, in _getRepoXML self._loadRepoXML(text=self) File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1388, in _loadRepoXML return self._groupLoadRepoXML(text, ["primary"]) File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1372, in _groupLoadRepoXML if self._commonLoadRepoXML(text): File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 1208, in _commonLoadRepoXML result = self._getFileRepoXML(local, text) File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 989, in _getFileRepoXML cache=self.http_caching == 'all') File "/usr/lib/python2.4/site-packages/yum/yumRepo.py", line 826, in _getFile http_headers=headers, File "/usr/lib/python2.4/site-packages/urlgrabber/mirror.py", line 412, in urlgrab return self._mirror_try(func, url, kw) File "/usr/lib/python2.4/site-packages/urlgrabber/mirror.py", line 398, in _mirror_try return func_ref( *(fullurl,), **kwargs ) File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 936, in urlgrab return self._retry(opts, retryfunc, url, filename) File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 854, in _retry r = apply(func, (opts,) + args, {}) File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 922, in retryfunc fo = URLGrabberFileObject(url, filename, opts) File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1010, in __init__ self._do_open() File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1093, in _do_open fo, hdr = self._make_request(req, opener) File "/usr/lib/python2.4/site-packages/urlgrabber/grabber.py", line 1202, in _make_request fo = opener.open(req) File "/usr/lib64/python2.4/urllib2.py", line 358, in open response = self._open(req, data) File "/usr/lib64/python2.4/urllib2.py", line 376, in _open '_open', req) File "/usr/lib64/python2.4/urllib2.py", line 337, in _call_chain result = func(*args) File "/usr/lib64/python2.4/site-packages/M2Crypto/m2urllib2.py", line 82, in https_open h.request(req.get_method(), req.get_selector(), req.data, headers) File "/usr/lib64/python2.4/httplib.py", line 810, in request self._send_request(method, url, body, headers) File "/usr/lib64/python2.4/httplib.py", line 833, in _send_request self.endheaders() File "/usr/lib64/python2.4/httplib.py", line 804, in endheaders self._send_output() File "/usr/lib64/python2.4/httplib.py", line 685, in _send_output self.send(msg) File "/usr/lib64/python2.4/httplib.py", line 652, in send self.connect() File "/usr/lib64/python2.4/site-packages/M2Crypto/httpslib.py", line 47, in connect self.sock.connect((self.host, self.port)) File "/usr/lib64/python2.4/site-packages/M2Crypto/SSL/Connection.py", line 174, in connect ret = self.connect_ssl() File "/usr/lib64/python2.4/site-packages/M2Crypto/SSL/Connection.py", line 167, in connect_ssl return m2.ssl_connect(self.ssl, self._timeout) M2Crypto.SSL.SSLError: certificate verify failed

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• C#: System.Collections.Concurrent.ConcurrentQueue vs. Queue

  - by James Michael Hare

  I love new toys, so of course when .NET 4.0 came out I felt like the proverbial kid in the candy store!  Now, some people get all excited about the IDE and it’s new features or about changes to WPF and Silver Light and yes, those are all very fine and grand.  But me, I get all excited about things that tend to affect my life on the backside of development.  That’s why when I heard there were going to be concurrent container implementations in the latest version of .NET I was salivating like Pavlov’s dog at the dinner bell. They seem so simple, really, that one could easily overlook them.  Essentially they are implementations of containers (many that mirror the generic collections, others are new) that have either been optimized with very efficient, limited, or no locking but are still completely thread safe -- and I just had to see what kind of an improvement that would translate into. Since part of my job as a solutions architect here where I work is to help design, develop, and maintain the systems that process tons of requests each second, the thought of extremely efficient thread-safe containers was extremely appealing.  Of course, they also rolled out a whole parallel development framework which I won’t get into in this post but will cover bits and pieces of as time goes by. This time, I was mainly curious as to how well these new concurrent containers would perform compared to areas in our code where we manually synchronize them using lock or some other mechanism.  So I set about to run a processing test with a series of producers and consumers that would be either processing a traditional System.Collections.Generic.Queue or a System.Collection.Concurrent.ConcurrentQueue. Now, I wanted to keep the code as common as possible to make sure that the only variance was the container, so I created a test Producer and a test Consumer.  The test Producer takes an Action<string> delegate which is responsible for taking a string and placing it on whichever queue we’re testing in a thread-safe manner: 1: internal class Producer 2: { 3: public int Iterations { get; set; } 4: public Action<string> ProduceDelegate { get; set; } 5: 6: public void Produce() 7: { 8: for (int i = 0; i < Iterations; i++) 9: { 10: ProduceDelegate(“Hello”); 11: } 12: } 13: } Then likewise, I created a consumer that took a Func<string> that would read from whichever queue we’re testing and return either the string if data exists or null if not.  Then, if the item doesn’t exist, it will do a 10 ms wait before testing again.  Once all the producers are done and join the main thread, a flag will be set in each of the consumers to tell them once the queue is empty they can shut down since no other data is coming: 1: internal class Consumer 2: { 3: public Func<string> ConsumeDelegate { get; set; } 4: public bool HaltWhenEmpty { get; set; } 5: 6: public void Consume() 7: { 8: bool processing = true; 9: 10: while (processing) 11: { 12: string result = ConsumeDelegate(); 13: 14: if(result == null) 15: { 16: if (HaltWhenEmpty) 17: { 18: processing = false; 19: } 20: else 21: { 22: Thread.Sleep(TimeSpan.FromMilliseconds(10)); 23: } 24: } 25: else 26: { 27: DoWork(); // do something non-trivial so consumers lag behind a bit 28: } 29: } 30: } 31: } Okay, now that we’ve done that, we can launch threads of varying numbers using lambdas for each different method of production/consumption.  First let's look at the lambdas for a typical System.Collections.Generics.Queue with locking: 1: // lambda for putting to typical Queue with locking... 2: var productionDelegate = s => 3: { 4: lock (_mutex) 5: { 6: _mutexQueue.Enqueue(s); 7: } 8: }; 9:  10: // and lambda for typical getting from Queue with locking... 11: var consumptionDelegate = () => 12: { 13: lock (_mutex) 14: { 15: if (_mutexQueue.Count > 0) 16: { 17: return _mutexQueue.Dequeue(); 18: } 19: } 20: return null; 21: }; Nothing new or interesting here.  Just typical locks on an internal object instance.  Now let's look at using a ConcurrentQueue from the System.Collections.Concurrent library: 1: // lambda for putting to a ConcurrentQueue, notice it needs no locking! 2: var productionDelegate = s => 3: { 4: _concurrentQueue.Enqueue(s); 5: }; 6:  7: // lambda for getting from a ConcurrentQueue, once again, no locking required. 8: var consumptionDelegate = () => 9: { 10: string s; 11: return _concurrentQueue.TryDequeue(out s) ? s : null; 12: }; So I pass each of these lambdas and the number of producer and consumers threads to launch and take a look at the timing results.  Basically I’m timing from the time all threads start and begin producing/consuming to the time that all threads rejoin.  I won't bore you with the test code, basically it just launches code that creates the producers and consumers and launches them in their own threads, then waits for them all to rejoin.  The following are the timings from the start of all threads to the Join() on all threads completing.  The producers create 10,000,000 items evenly between themselves and then when all producers are done they trigger the consumers to stop once the queue is empty. These are the results in milliseconds from the ordinary Queue with locking: 1: Consumers Producers 1 2 3 Time (ms) 2: ---------- ---------- ------ ------ ------ --------- 3: 1 1 4284 5153 4226 4554.33 4: 10 10 4044 3831 5010 4295.00 5: 100 100 5497 5378 5612 5495.67 6: 1000 1000 24234 25409 27160 25601.00 And the following are the results in milliseconds from the ConcurrentQueue with no locking necessary: 1: Consumers Producers 1 2 3 Time (ms) 2: ---------- ---------- ------ ------ ------ --------- 3: 1 1 3647 3643 3718 3669.33 4: 10 10 2311 2136 2142 2196.33 5: 100 100 2480 2416 2190 2362.00 6: 1000 1000 7289 6897 7061 7082.33 Note that even though obviously 2000 threads is quite extreme, the concurrent queue actually scales really well, whereas the traditional queue with simple locking scales much more poorly. I love the new concurrent collections, they look so much simpler without littering your code with the locking logic, and they perform much better.  All in all, a great new toy to add to your arsenal of multi-threaded processing!

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• error while running ruby application at system startup in ubuntu

  - by anjo

  I am on Ubuntu 12.04 machine. Have a script file which runs when entered manually in terminal gnome-terminal -e /home/precise/Desktop/cartodb/script.sh The content of script file is cd /home/ubuntupc/Desktop/cartodb20/ sh /home/ubuntupc/.rvm/scripts/rvm bundle exec foreman start -p 3000 So what i tried to do is to run this script at every system start up. So on Startup Applications command: gnome-terminal -e /home/precise/Desktop/cartodb/script.sh On terminal Edit - Profile Preferences - Title and Command Checked the "Run command as a login shell" But this seems to be not working. When restarted the machine found these error in terminal The child process exited normally with status 127. ERROR: RVM Ruby not used, run `rvm use ruby` first. Some info regarding the installed packages and system. $ which ruby /home/ubuntupc/.rvm/rubies/ruby-1.9.2-p320/bin/ruby $ which rails /home/ubuntupc/.rvm/gems/ruby-1.9.2-p320/bin/rails $ which gem /home/ubuntupc/.rvm/rubies/ruby-1.9.2-p320/bin/gem $ cat ~/.bash_profile [[ -s "$HOME/.profile" ]] && source "$HOME/.profile" # Load the default .profile [[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Load RVM into a shell session *as a function* $ which -a ruby /home/ubuntupc/.rvm/rubies/ruby-1.9.2-p320/bin/ruby $ sudo update-alternatives --config ruby update-alternatives: error: no alternatives for ruby. $ sudo find / -name "rubygems" -print /home/ubuntupc/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/site_ruby/1.9.1/rubygems /home/ubuntupc/.rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/rubygems /home/ubuntupc/.rvm/src/ruby-1.9.2-p320/lib/rubygems /home/ubuntupc/.rvm/src/ruby-1.9.2-p320/test/rubygems /home/ubuntupc/.rvm/src/ruby-1.9.2-p320/test/rubygems/rubygems /home/ubuntupc/.rvm/src/ruby-1.9.2-p320/doc/rubygems /home/ubuntupc/.rvm/src/rubygems-2.2.1/lib/rubygems /home/ubuntupc/.rvm/src/rubygems-2.2.1/test/rubygems /home/ubuntupc/.rvm/src/rubygems-2.2.1/test/rubygems/rubygems /home/ubuntupc/.rvm/src/rvm/scripts/functions/rubygems /home/ubuntupc/.rvm/src/rvm/scripts/rubygems /home/ubuntupc/.rvm/scripts/functions/rubygems /home/ubuntupc/.rvm/scripts/rubygems /usr/lib/ruby/1.9.1/rubygems /usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/site_ruby/1.9.1/rubygems /usr/local/rvm/rubies/ruby-1.9.2-p320/lib/ruby/1.9.1/rubygems /usr/local/rvm/src/ruby-1.9.2-p320/lib/rubygems /usr/local/rvm/src/ruby-1.9.2-p320/test/rubygems /usr/local/rvm/src/ruby-1.9.2-p320/test/rubygems/rubygems /usr/local/rvm/src/ruby-1.9.2-p320/doc/rubygems /usr/local/rvm/src/rubygems-2.2.0/lib/rubygems /usr/local/rvm/src/rubygems-2.2.0/test/rubygems /usr/local/rvm/src/rubygems-2.2.0/test/rubygems/rubygems /usr/local/rvm/src/rvm/scripts/functions/rubygems /usr/local/rvm/src/rvm/scripts/rubygems /usr/local/rvm/scripts/functions/rubygems /usr/local/rvm/scripts/rubygems Please point out what i am missing as i am new to the ruby applications. Thanks in advance

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• Find a Hash Collision, Win $100

  - by Mike C

  Margarity Kerns recently published a very nice article at SQL Server Central on using hash functions to detect changes in rows during the data warehouse load ETL process. On the discussion page for the article I noticed a lot of the same old arguments against using hash functions to detect change. After having this same discussion several times over the past several months in public and private forums, I've decided to see if we can't put this argument to rest for a while. To that end I'm going to...(read more)

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• How To Use Regular Expressions for Data Validation and Cleanup

  You need to provide data validation at the server level for complex strings like phone numbers, email addresses, etc. You may also need to do data cleanup / standardization before moving it from source to target. Although SQL Server provides a fair number of string functions, the code developed with these built-in functions can become complex and hard to maintain or reuse. The Future of SQL Server Monitoring "Being web-based, SQL Monitor 2.0 enables you to check on your servers from almost any location" Jonathan Allen.Try SQL Monitor now.

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• The Application Architecture Domain

  - by Michael Glas

  I have been spending a lot of time thinking about Application Architecture in the context of EA. More specifically, as an Enterprise Architect, what do I need to consider when looking at/defining/designing the Application Architecture Domain?There are several definitions of Application Architecture. TOGAF says “The objective here [in Application Architecture] is to define the major kinds of application system necessary to process the data and support the business”. FEA says the Application Architecture “Defines the applications needed to manage the data and support the business functions”.I agree with these definitions. They reflect what the Application Architecture domain does. However, they need to be decomposed to be practical.I find it useful to define a set of views into the Application Architecture domain. These views reflect what an EA needs to consider when working with/in the Applications Architecture domain. These viewpoints are, at a high level:Capability View: This view reflects how applications alignment with business capabilities. It is a super set of the following views when viewed in aggregate. By looking at the Application Architecture domain in terms of the business capabilities it supports, you get a good perspective on how those applications are directly supporting the business.Technology View: The technology view reflects the underlying technology that makes up the applications. Based on the number of rationalization activities I have seen (more specifically application rationalization), the phrase “complexity equals cost” drives the importance of the technology view, especially when attempting to reduce that complexity through standardization type activities. Some of the technology components to be considered are: Software: The application itself as well as the software the application relies on to function (web servers, application servers). Infrastructure: The underlying hardware and network components required by the application and supporting application software. Development: How the application is created and maintained. This encompasses development components that are part of the application itself (i.e. customizable functions), as well as bolt on development through web services, API’s, etc. The maintenance process itself also falls under this view. Integration: The interfaces that the application provides for integration as well as the integrations to other applications and data sources the application requires to function. Type: Reflects the kind of application (mash-up, 3 tiered, etc). (Note: functional type [CRM, HCM, etc.] are reflected under the capability view). Organization View: Organizations are comprised of people and those people use applications to do their jobs. Trying to define the application architecture domain without taking the organization that will use/fund/change it into consideration is like trying to design a car without thinking about who will drive it (i.e. you may end up building a formula 1 car for a family of 5 that is really looking for a minivan). This view reflects the people aspect of the application. It includes: Ownership: Who ‘owns’ the application? This will usually reflect primary funding and utilization but not always. Funding: Who funds both the acquisition/creation as well as the on-going maintenance (funding to create/change/operate)? Change: Who can/does request changes to the application and what process to the follow? Utilization: Who uses the application, how often do they use it, and how do they use it? Support: Which organization is responsible for the on-going support of the application? Information View: Whether or not you subscribe to the view that “information drives the enterprise”, it is a fact that information is critical. The management, creation, and organization of that information are primary functions of enterprise applications. This view reflects how the applications are tied to information (or at a higher level – how the Application Architecture domain relates to the Information Architecture domain). It includes: Access: The application is the mechanism by which end users access information. This could be through a primary application (i.e. CRM application), or through an information access type application (a BI application as an example). Creation: Applications create data in order to provide information to end-users. (I.e. an application creates an order to be used by an end-user as part of the fulfillment process). Consumption: Describes the data required by applications to function (i.e. a product id is required by a purchasing application to create an order. Application Service View: Organizations today are striving to be more agile. As an EA, I need to provide an architecture that supports this agility. One of the primary ways to achieve the required agility in the application architecture domain is through the use of ‘services’ (think SOA, web services, etc.). Whether it is through building applications from the ground up utilizing services, service enabling an existing application, or buying applications that are already ‘service enabled’, compartmentalizing application functions for re-use helps enable flexibility in the use of those applications in support of the required business agility. The applications service view consists of: Services: Here, I refer to the generic definition of a service “a set of related software functionalities that can be reused for different purposes, together with the policies that should control its usage”. Functions: The activities within an application that are not available / applicable for re-use. This view is helpful when identifying duplication functions between applications that are not service enabled. Delivery Model View: It is hard to talk about EA today without hearing the terms ‘cloud’ or shared services.  Organizations are looking at the ways their applications are delivered for several reasons, to reduce cost (both CAPEX and OPEX), to improve agility (time to market as an example), etc.  From an EA perspective, where/how an application is deployed has impacts on the overall enterprise architecture. From integration concerns to SLA requirements to security and compliance issues, the Enterprise Architect needs to factor in how applications are delivered when designing the Enterprise Architecture. This view reflects how applications are delivered to end-users. The delivery model view consists of different types of delivery mechanisms/deployment options for applications: Traditional: Reflects non-cloud type delivery options. The most prevalent consists of an application running on dedicated hardware (usually specific to an environment) for a single consumer. Private Cloud: The application runs on infrastructure provisioned for exclusive use by a single organization comprising multiple consumers. Public Cloud: The application runs on infrastructure provisioned for open use by the general public. Hybrid: The application is deployed on two or more distinct cloud infrastructures (private, community, or public) that remain unique entities, but are bound together by standardized or proprietary technology that enables data and application portability. While by no means comprehensive, I find that applying these views to the application domain gives a good understanding of what an EA needs to consider when effecting changes to the Application Architecture domain.Finally, the application architecture domain is one of several architecture domains that an EA must consider when developing an overall Enterprise Architecture. The Oracle Enterprise Architecture Framework defines four Primary domains: Business Architecture, Application Architecture, Information Architecture, and Technology Architecture. Each domain links to the others either directly or indirectly at some point. Oracle links them at a high level as follows:Business Capabilities and/or Business Processes (Business Architecture), links to the Applications that enable the capability/process (Applications Architecture – COTS, Custom), links to the Information Assets managed/maintained by the Applications (Information Architecture), links to the technology infrastructure upon which all this runs (Technology Architecture - integration, security, BI/DW, DB infrastructure, deployment model). There are however, times when the EA needs to narrow focus to a particular domain for some period of time. These views help me to do just that.

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• T-SQL Tuesday # 16 : This is not the aggregate you're looking for

  - by AaronBertrand

  This week, T-SQL Tuesday is being hosted by Jes Borland ( blog | twitter ), and the theme is " Aggregate Functions ." When people think of aggregates, they tend to think of MAX(), SUM() and COUNT(). And occasionally, less common functions such as AVG() and STDEV(). I thought I would write a quick post about a different type of aggregate: string concatenation. Even going back to my classic ASP days, one of the more common questions out in the community has been, "how do I turn a column into a comma-separated...(read more)

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• Unit testing in Django

  - by acjohnson55

  I'm really struggling to write effective unit tests for a large Django project. I have reasonably good test coverage, but I've come to realize that the tests I've been writing are definitely integration/acceptance tests, not unit tests at all, and I have critical portions of my application that are not being tested effectively. I want to fix this ASAP. Here's my problem. My schema is deeply relational, and heavily time-oriented, giving my model object high internal coupling and lots of state. Many of my model methods query based on time intervals, and I've got a lot of auto_now_add going on in timestamped fields. So take a method that looks like this for example: def summary(self, startTime=None, endTime=None): # ... logic to assign a proper start and end time # if none was provided, probably using datetime.now() objects = self.related_model_set.manager_method.filter(...) return sum(object.key_method(startTime, endTime) for object in objects) How does one approach testing something like this? Here's where I am so far. It occurs to me that the unit testing objective should be given some mocked behavior by key_method on its arguments, is summary correctly filtering/aggregating to produce a correct result? Mocking datetime.now() is straightforward enough, but how can I mock out the rest of the behavior? I could use fixtures, but I've heard pros and cons of using fixtures for building my data (poor maintainability being a con that hits home for me). I could also setup my data through the ORM, but that can be limiting, because then I have to create related objects as well. And the ORM doesn't let you mess with auto_now_add fields manually. Mocking the ORM is another option, but not only is it tricky to mock deeply nested ORM methods, but the logic in the ORM code gets mocked out of the test, and mocking seems to make the test really dependent on the internals and dependencies of the function-under-test. The toughest nuts to crack seem to be the functions like this, that sit on a few layers of models and lower-level functions and are very dependent on the time, even though these functions may not be super complicated. My overall problem is that no matter how I seem to slice it, my tests are looking way more complex than the functions they are testing.

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• Encrypting your SQL Server Passwords in Powershell

  - by laerte

  A couple of months ago, a friend of mine who is now bewitched by the seemingly supernatural abilities of Powershell (+1 for the team) asked me what, initially, appeared to be a trivial question: "Laerte, I do not have the luxury of being able to work with my SQL servers through Windows Authentication, and I need a way to automatically pass my username and password. How would you suggest I do this?" Given that I knew he, like me, was using the SQLPSX modules (an open source project created by Chad Miller; a fantastic library of reusable functions and PowerShell scripts), I merrily replied, "Simply pass the Username and Password in SQLPSX functions". He rather pointed responded: "My friend, I might as well pass: Username-'Me'-password 'NowEverybodyKnowsMyPassword'" As I do have the pleasure of working with Windows Authentication, I had not really thought this situation though yet (and thank goodness I only revealed my temporary ignorance to a friend, and the embarrassment was minimized). After discussing this puzzle with Chad Miller, he showed me some code for saving passwords on SQL Server Tables, which he had demo'd in his Powershell ETL session at Tampa SQL Saturday (and you can download the scripts from here). The solution seemed to be pretty much ready to go, so I showed it to my Authentication-impoverished friend, only to discover that we were only half-way there: "That's almost what I want, but the details need to be stored in my local txt file, together with the names of the servers that I'll actually use the Powershell scripts on. Something like: Server1,UserName,Password Server2,UserName,Password" I thought about it for just a few milliseconds (Ha! Of course I'm not telling you how long it actually took me, I have to do my own marketing, after all) and the solution was finally ready. First , we have to download Library-StringCripto (with many thanks to Steven Hystad), which is composed of two functions: One for encryption and other for decryption, both of which are used to manage the password. If you want to know more about the library, you can see more details in the help functions. Next, we have to create a txt file with your encrypted passwords:$ServerName = "Server1" $UserName = "Login1" $Password = "Senha1" $PasswordToEncrypt = "YourPassword" $UserNameEncrypt = Write-EncryptedString -inputstring $UserName -Password $PasswordToEncrypt $PasswordEncrypt = Write-EncryptedString -inputstring $Password -Password $PasswordToEncrypt "$($Servername),$($UserNameEncrypt),$($PasswordEncrypt)" | Out-File c:\temp\ServersSecurePassword.txt -Append $ServerName = "Server2" $UserName = "Login2" $Password = "senha2" $PasswordToEncrypt = "YourPassword" $UserNameEncrypt = Write-EncryptedString -inputstring $UserName -Password $PasswordToEncrypt $PasswordEncrypt = Write-EncryptedString -inputstring $Password -Password $PasswordToEncrypt "$($Servername),$($UserNameEncrypt),$($PasswordEncrypt)" | Out-File c:\temp\ ServersSecurePassword.txt -Append .And in the c:\temp\ServersSecurePassword.txt file which we've just created, you will find your Username and Password, all neatly encrypted. Let's take a look at what the txt looks like: .and in case you're wondering, Server names, Usernames and Passwords are all separated by commas. Decryption is actually much more simple:Read-EncryptedString -InputString $EncryptString -password "YourPassword" (Just remember that the Password you're trying to decrypt must be exactly the same as the encrypted phrase.) Finally, just to show you how smooth this solution is, let's say I want to use the Invoke-DBMaint function from SQLPSX to perform a checkdb on a system database: it's just a case of split, decrypt and be happy!Get-Content c:\temp\ServerSecurePassword.txt | foreach { [array] $Split = ($_).split(",") Invoke-DBMaint -server $($Split[0]) -UserName (Read-EncryptedString -InputString $Split[1] -password "YourPassword" ) -Password (Read-EncryptedString -InputString $Split[2] -password "YourPassword" ) -Databases "SYSTEM" -Action "CHECK_DB" -ReportOn c:\Temp } This is why I love Powershell.

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• Brother MFC 7220 Replacement Toner

  In years past, printers were solely for the purpose of making copies in the office. Today, printers come with many functions so many office functions can be done using the same equipment. The Brother... [Author: Ben Pate - Computers and Internet - March 31, 2010]

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• We've completed the first iteration

  - by CliveT

  There are a lot of features in C# that are implemented by the compiler and not by the underlying platform. One such feature is a lambda expression. Since local variables cannot be accessed once the current method activation finishes, the compiler has to go out of its way to generate a new class which acts as a home for any variable whose lifetime needs to be extended past the activation of the procedure. Take the following example:     Random generator = new Random();     Func func = () = generator.Next(10); In this case, the compiler generates a new class called c_DisplayClass1 which is marked with the CompilerGenerated attribute. [CompilerGenerated] private sealed class c__DisplayClass1 {     // Fields     public Random generator;     // Methods     public int b__0()     {         return this.generator.Next(10);     } } Two quick comments on this: (i)    A display was the means that compilers for languages like Algol recorded the various lexical contours of the nested procedure activations on the stack. I imagine that this is what has led to the name. (ii)    It is a shame that the same attribute is used to mark all compiler generated classes as it makes it hard to figure out what they are being used for. Indeed, you could imagine optimisations that the runtime could perform if it knew that classes corresponded to certain high level concepts. We can see that the local variable generator has been turned into a field in the class, and the body of the lambda expression has been turned into a method of the new class. The code that builds the Func object simply constructs an instance of this class and initialises the fields to their initial values.     c__DisplayClass1 class2 = new c__DisplayClass1();     class2.generator = new Random();     Func func = new Func(class2.b__0); Reflector already contains code to spot this pattern of code and reproduce the form containing the lambda expression, so this is example is correctly decompiled. The use of compiler generated code is even more spectacular in the case of iterators. C# introduced the idea of a method that could automatically store its state between calls, so that it can pick up where it left off. The code can express the logical flow with yield return and yield break denoting places where the method should return a particular value and be prepared to resume.         {             yield return 1;             yield return 2;             yield return 3;         } Of course, there was already a .NET pattern for expressing the idea of returning a sequence of values with the computation proceeding lazily (in the sense that the work for the next value is executed on demand). This is expressed by the IEnumerable interface with its Current property for fetching the current value and the MoveNext method for forcing the computation of the next value. The sequence is terminated when this method returns false. The C# compiler links these two ideas together so that an IEnumerator returning method using the yield keyword causes the compiler to produce the implementation of an Iterator. Take the following piece of code.         IEnumerable GetItems()         {             yield return 1;             yield return 2;             yield return 3;         } The compiler implements this by defining a new class that implements a state machine. This has an integer state that records which yield point we should go to if we are resumed. It also has a field that records the Current value of the enumerator and a field for recording the thread. This latter value is used for optimising the creation of iterator instances. [CompilerGenerated] private sealed class d__0 : IEnumerable, IEnumerable, IEnumerator, IEnumerator, IDisposable {     // Fields     private int 1__state;     private int 2__current;     public Program 4__this;     private int l__initialThreadId; The body gets converted into the code to construct and initialize this new class. private IEnumerable GetItems() {     d__0 d__ = new d__0(-2);     d__.4__this = this;     return d__; } When the class is constructed we set the state, which was passed through as -2 and the current thread. public d__0(int 1__state) {     this.1__state = 1__state;     this.l__initialThreadId = Thread.CurrentThread.ManagedThreadId; } The state needs to be set to 0 to represent a valid enumerator and this is done in the GetEnumerator method which optimises for the usual case where the returned enumerator is only used once. IEnumerator IEnumerable.GetEnumerator() {     if ((Thread.CurrentThread.ManagedThreadId == this.l__initialThreadId)               && (this.1__state == -2))     {         this.1__state = 0;         return this;     } The state machine itself is implemented inside the MoveNext method. private bool MoveNext() {     switch (this.1__state)     {         case 0:             this.1__state = -1;             this.2__current = 1;             this.1__state = 1;             return true;         case 1:             this.1__state = -1;             this.2__current = 2;             this.1__state = 2;             return true;         case 2:             this.1__state = -1;             this.2__current = 3;             this.1__state = 3;             return true;         case 3:             this.1__state = -1;             break;     }     return false; } At each stage, the current value of the state is used to determine how far we got, and then we generate the next value which we return after recording the next state. Finally we return false from the MoveNext to signify the end of the sequence. Of course, that example was really simple. The original method body didn't have any local variables. Any local variables need to live between the calls to MoveNext and so they need to be transformed into fields in much the same way that we did in the case of the lambda expression. More complicated MoveNext methods are required to deal with resources that need to be disposed when the iterator finishes, and sometimes the compiler uses a temporary variable to hold the return value. Why all of this explanation? We've implemented the de-compilation of iterators in the current EAP version of Reflector (7). This contrasts with previous version where all you could do was look at the MoveNext method and try to figure out the control flow. There's a fair amount of things we have to do. We have to spot the use of a CompilerGenerated class which implements the Enumerator pattern. We need to go to the class and figure out the fields corresponding to the local variables. We then need to go to the MoveNext method and try to break it into the various possible states and spot the state transitions. We can then take these pieces and put them back together into an object model that uses yield return to show the transition points. After that Reflector can carry on optimising using its usual optimisations. The pattern matching is currently a little too sensitive to changes in the code generation, and we only do a limited analysis of the MoveNext method to determine use of the compiler generated fields. In some ways, it is a pity that iterators are compiled away and there is no metadata that reflects the original intent. Without it, we are always going to dependent on our knowledge of the compiler's implementation. For example, we have noticed that the Async CTP changes the way that iterators are code generated, so we'll have to do some more work to support that. However, with that warning in place, we seem to do a reasonable job of decompiling the iterators that are built into the framework. Hopefully, the EAP will give us a chance to find examples where we don't spot the pattern correctly or regenerate the wrong code, and we can improve things. Please give it a go, and report any problems.

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• Difference between IN and FIND_IN_SET

  - by Madhan ayyasamy

  Hi Friends,You may be confused with IN() and FIND_IN_SET() MYSQL functions. There are specific case/situation for both functions where to use which Mysql function. Look at below explanation about IN() and FIND_IN_SET()IN() : This function is used when you have a list of possible values and a single value in your database.Example: WHERE memberid IN (1,2,3)FIND_IN_SET() : This function is used where you have comma separated list of values stored in database and want to see if a certain value exists in that comma seperated list.Example: WHERE FIND_IN_SET( ‘table column name like id’, 'dynamic idlist' )

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• Should one comment differently in functional languages

  - by Tom Squires

  I'm just getting started with functional programming and I'm wondering the correct way to comment my code. It seems a little redundant to comment a short function as the names and signature already should tell you everything you need to know. Commenting larger functions also seems a little redundant since they are generally comprised of smaller self-descriptive functions. What is the correct way to comment a functional program? Should I use the same approach as in iterative programming?

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• Codeigniter Controller function in a view [closed]

  - by Y2ok

  I'm using CodeIgniter and I have two controllers: Index controller that loads the website view Personal panel controller that will do all login, registration and personal panel functions. (Functions are loaded from models.) The problem is that I don't have any clue how to insert that controller in a view file or in the other controller file so that it would load when I press submit button for a form or if the session's loggedin is with value true.

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