Weird Path in Git directory Structure -

-

i have seen following path in directory of .git.

.git/object/3b/12abef878787483abeceddaa5544489abff789a

when infact sha 3b12abef878787483abeceddaa5544489abff789a

which sha of contents of file , hence should stored without /. why did git store blob in weird path,what advantages of doing so?

the reason prevent there being many files in 1 directory. sha values start 3b stored in sub-directory 3b, workload on single directory 1/256th of if blobs in single directory. ultimately, speeds performance; there less searching find particular blob.

you can see similar effects in terminfo directory, entries sub-divided directories based on first letter of terminal entry. cpan system has authors/id/a/aa/aardvark in naming hierarchy.

please elaborate little bit me.

suppose git wants find blob 3b12abef878787483abeceddaa5544489abff789a , directory partitioning scheme not in use. there might be, sake of argument, 512 blobs, , file, kernel might have read 512 directory entries in .git/objects find right entry.

now suppose directory partitioning scheme in use, , miracle of statistical mischance, there 256 subdirectories each containing 2 files. kernel @ worst has read 256 directory entries 2-byte names in each entry (compared 512 directory entries 32-byte names) in ./git/objects directory, , has read @ worst 2 entries 30-byte names in ./git/objects/3b directory.

there complicating factors, such imperfectly balanced hashing , memory caching , disk accesses, general idea distributing files multiple subdirectories means os kernel has less work find file. if number of files in directory extend multiple hundreds, worth considering breaking down.


Comments

Post a Comment

Popular posts from this blog

php - Magento - Deleted Base url key -

-
i working on cleaning url: http://mydomain.com/shop/shop/deals i going through settings in configuration tab in admin panel on magento , change secure , unsecure base urls remove first base url "shop" web page read: http://mydomain.com/shop/deals so changed unsecure base urls mydomain.com/shop mydomain.com , secure 12.345.67.89/shop 12.345.67.89. wrong thing do. i cannot reload page or admin console. how access these files through ftp , change correctly there?? when make changes in admin panel changes made in database not in file. have make changes in database. 1.go database , select core_config_data table under table find web/unsecure/base_url , web/secure/base_url . make changes here. don't forget clear cache in var/cache folder
Read more

javascript - Tooltipster plugin not firing jquery function when button or any click even occur -

-
i want use tooltipster plugin click element in body show tooltip , want have close button inside tooltip close it. however use jquery click() function handle won't fired. tried solution in post. worked when tooltip triggered hover event. tooltipster plugin not firing jquery function when link in in tooltip clicked the original solution using hover in jsfiddle trigger: 'hover', instead using click show tooltip trigger: 'click', http://jsfiddle.net/bcqyl/7/ it won't fire click event in jquery block. can captured normal javascript function only. checked should code in tooltipster plugin locked , captured "click()" event inside tips when in click trigger mode. i tried other event onchange event of radio button fired when using code in original solution @evan right. tooltip doesn't exist in dom , can't bind/delegate action (even if go way $(document) after domready). if you're after close button inside of too...
Read more

java - WrongTypeOfReturnValue exception thrown when unit testing using mockito -

-
my test list<person> mylist; @test public void testisvalidperson() { mylist = new arraylist<person>(); mylist.add(new person("tom")); when(persondao.get(person)).thenreturn(mylist); when((persondao.get(person)).isempty()).thenreturn(false);//------exception thrown boolean result = service.isvalid("tom"); assertfalse(result); } method tested: public boolean isvalid(string person){ persondao = new persondao(); person personobj = new person(person); return (persondao.get(person).isempty())?false : true; } exception thrown: org.mockito.exceptions.misusing.wrongtypeofreturnvalue: boolean cannot returned get() get() should return list *** if you're unsure why you're getting above error read on. due nature of syntax above problem might occur because: 1. exception *might* occur in wrongly written multi-threaded tests. please refer mockito faq on limitations of concurrency testing. 2. sp...
Read more