{"id":712,"date":"2006-06-09T11:58:20","date_gmt":"2006-06-09T01:58:20","guid":{"rendered":"http:\/\/www.flamingspork.com\/blog\/2006\/06\/09\/matt-on-ruby-resource-management-and-why-you-can-do-it-elsewhere\/"},"modified":"2006-06-09T11:58:20","modified_gmt":"2006-06-09T01:58:20","slug":"matt-on-ruby-resource-management-and-why-you-can-do-it-elsewhere","status":"publish","type":"post","link":"https:\/\/www.flamingspork.com\/blog\/2006\/06\/09\/matt-on-ruby-resource-management-and-why-you-can-do-it-elsewhere\/","title":{"rendered":"Matt on Ruby resource management (and why you can do it elsewhere)"},"content":{"rendered":"

ERROR: The requested URL could not be retrieved<\/a> (yeah, site didn’t work when i clicked on it from RSS).<\/p>\n

Matt uses this bit of ruby code to demonstrate that here you can’t ever not close the file handle:<\/p>\n

File.open('something.txt') do |fd|
\n# Manipulate the file through 'fd'
\nend
\n# File handle is now closed<\/code><\/p>\n

Which seems pretty cool. However, a good C++ programmer can also acheive the same (or better) things!<\/p>\n

For example, in NDB (well, in the portability library we use inside NDB) we have a class called Guard. The constructor for Guard pthread_mutex_locks a mutex. The destructor unlocks it. So, for when you’ve got some simple mutual exclusion you need doing, you can have bits of code like this:<\/p>\n

{
\nGuard g(m_config_mutex);<\/p>\n

if(m_config.foo<10)
\nreturn -1;<\/p>\n

\/\/ other_stuff
\n}<\/code><\/p>\n

Guess what, those nice little error checking bits that should just return -1 look a lot cleaner and you can never forget to unlock the mutex! You’ll see code like this in the management server (ndb_mgmd – source in storage\/ndb\/src\/mgmsrvr\/ mostly in MgmtSrvr.cpp).<\/p>\n

In fact, you can do this with files as well (multiple ones)\u00c2\u00a0 and have them all closed on exit from the block. It’s all a matter of having (or writing) some good classes. I’m no Ruby expert – but I think you’d have to have more indentation to do that with two files?<\/p>\n","protected":false},"excerpt":{"rendered":"

ERROR: The requested URL could not be retrieved (yeah, site didn’t work when i clicked on it from RSS). Matt uses this bit of ruby code to demonstrate that here you can’t ever not close the file handle: File.open(‘something.txt’) do … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1,14],"tags":[],"class_list":["post-712","post","type-post","status-publish","format-standard","hentry","category-general","category-mysql"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5a6n8-bu","jetpack-related-posts":[{"id":1013,"url":"https:\/\/www.flamingspork.com\/blog\/2008\/02\/20\/a-world-of-fail\/","url_meta":{"origin":712,"position":0},"title":"A world of FAIL","author":"Stewart Smith","date":"2008-02-20","format":false,"excerpt":"=================================== ERROR ==================================== File holyfoot\/hf@mysql.com\/deer.(none)|mysql-test\/r\/bdb_notembedded.result|20061113160642|60022|276fa5181da9a588 is marked as gone in this repository and therefor cannot accept updates. The fact that you are getting updates indicates that the file is not gone in the other repository and could be restored in this repository. if you want to \"un-gone\" the file(s) using\u2026","rel":"","context":"In "mysql"","block_context":{"text":"mysql","link":"https:\/\/www.flamingspork.com\/blog\/category\/work-et-al\/mysql\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":914,"url":"https:\/\/www.flamingspork.com\/blog\/2007\/11\/09\/mysql-5122-stew2\/","url_meta":{"origin":712,"position":1},"title":"mysql-5.1.22-stew2","author":"Stewart Smith","date":"2007-11-09","format":false,"excerpt":"New: Updated NDB Compressed LCP and BACKUP patches (now with O_DIRECT support) InnoDB patch for Windows that should give ~5x improvement on commits\/sec (Bug31876) Everything in current telco-6.3 tree (ndb ~6.3.5) Lots of NDB improvements and new features over regular 5.1. 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We're getting a few more warnings on Win64 (some of which look merely semantic, while\u2026","rel":"","context":"In "General"","block_context":{"text":"General","link":"https:\/\/www.flamingspork.com\/blog\/category\/general\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":711,"url":"https:\/\/www.flamingspork.com\/blog\/2006\/06\/09\/a-bug-on-failure-failure\/","url_meta":{"origin":712,"position":4},"title":"a bug on failure failure","author":"Stewart Smith","date":"2006-06-09","format":false,"excerpt":"I've been working on BUG#17928, which is all about \"testBackup fails in error handling testcases\" which appeared after we merged in some work to the 5.1 tree (which is okay in 5.0) that changes some things in the way that online backups are done in NDB to better support recovery\u2026","rel":"","context":"In "General"","block_context":{"text":"General","link":"https:\/\/www.flamingspork.com\/blog\/category\/general\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":1650,"url":"https:\/\/www.flamingspork.com\/blog\/2009\/05\/27\/pluggable-metadata-stores-or-the-revenge-of-table-discovery\/","url_meta":{"origin":712,"position":5},"title":"Pluggable Metadata stores (or… the revenge of table discovery)","author":"Stewart Smith","date":"2009-05-27","format":false,"excerpt":"Users of the ARCHIVE or NDB storage engines in MySQL may be aware of a MySQL feature known as \"table discovery\". 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