Handle multiple pulls in Local Git Repo

Question

I have Sinatra service that updates a local git repo by executing git pull when it is hit. Since it is a write, I want only one git pull to happen at a time. How do I effectively detect if a pull is already happening ? Currently am just checking if index.lock file exists in .git directory.

if @file_obj.exists? "#{@data_dir}/.git/index.lock"
    @log.info('********* LOCKED **********')
else
  MUTEX.synchronize do
    @log.info('********* Inside Sync **********')
    @executor.run(git_pull_command, in: @data_dir)
  end
end

Answer 1

index.lock is probably the only file that you need to worry about. Since you're using a mutex to synchronize your operations, this code should be fine.

Git only really creates the index.lock file when it needs to have sole control over the index for a while (and to prevent other Git processes from clobbering stuff). This would only happen while the pull is completing.