# How often does git calculate SHAs? 2 messages from 2012-01-30 to 2012-01-30. Participants: Michael Cook, Shawn Pearce. Thread: https://gitlist.dev/t/29479 ## Michael Cook, 2012-01-30 14:25 Subject: How often does git calculate SHAs? Message-ID: <4F26A864.1080702@bbn.com> URL: https://gitlist.dev/e/4F26A864.1080702%40bbn.com ``` How often does git actually calculate a file's SHA? `strace git status` shows that git stat'ed many files, but opened only a few. So I assume git has some heuristicsbased on the stat infofor when to recalculate the SHAs. Any pointers to how I could have figured this out myself from looking at the source code would be appreciated. Google wasn't helpful. Michael -- Michael Cook, Raytheon BBN Technologies, www.bbn.com ``` ## Shawn Pearce, 2012-01-30 14:59 Subject: Re: How often does git calculate SHAs? Message-ID: URL: https://gitlist.dev/e/CAJo%3DhJtEPTPTwdoFaoZH4OBpfnCR3VDUNGdNtCprmPf%3D13xrdQ%40mail.gmail.com In-Reply-To: <4F26A864.1080702@bbn.com> ``` On Mon, Jan 30, 2012 at 06:25, Michael Cook wrote: > How often does git actually calculate a file's SHA? > > `strace git status` shows that git stat'ed many files, but opened only a > few. So I assume git has some heuristicsbased on the stat infofor when to > recalculate the SHAs. > > Any pointers to how I could have figured this out myself from looking at the > source code would be appreciated. Google wasn't helpful. During `git status` Git performs an lstat() of every file in the working tree. If the file matches stat structure data with the cache held in .git/index, Git assumes the file is unmodified. Things Git are looking for is usually size, mtime, inode number, creation time, etc. ```