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Commit Description:
removed many 'system' invokations
Commit Description:
removed many 'system' invokations
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Jittat Fakcharoenphol-
lib/dir_init.rb
| 109 lines
| 2.7 KiB
| text/x-ruby
| RubyLexer
|
jittat
|
r71 | require 'ftools' | ||
| # DirInit::Manager handles directory initialization and clean-up when | ||||
| # there are many concurrent processes that wants to modify the | ||||
| # directory in the same way. | ||||
| # | ||||
| # An example usage is when each process wants to copy some temporary | ||||
| # files to the directory and delete these files after finishing its | ||||
| # job. Problems may occur when the first process delete the files | ||||
| # while the second process is still using the files. | ||||
| # | ||||
| # This library maintain a reference counter on the processes using the | ||||
| # directory. It locks the dir to manage critical section when | ||||
| # updating the reference counter. | ||||
| module DirInit | ||||
| class Manager | ||||
| def initialize(dir_name, usage_filename='.usage_counter') | ||||
| @dir_name = dir_name | ||||
| @usage_filename = usage_filename | ||||
| end | ||||
| # Check if someone has initialized the dir. If not, call block. | ||||
| def setup # :yields: block | ||||
| dir = File.new(@dir_name) | ||||
| dir.flock(File::LOCK_EX) | ||||
| begin | ||||
| counter_filename = get_counter_filename | ||||
| if File.exist? counter_filename | ||||
| # someone is here | ||||
| f = File.new(counter_filename,"r+") | ||||
| counter = f.read.to_i | ||||
| f.seek(0) | ||||
| f.write("#{counter+1}\n") | ||||
| f.close | ||||
| else | ||||
| # i'm the first, create the counter file | ||||
| counter = 0 | ||||
| f = File.new(counter_filename,"w") | ||||
| f.write("1\n") | ||||
| f.close | ||||
| end | ||||
| # if no one is here | ||||
| if counter == 0 | ||||
| if block_given? | ||||
| yield | ||||
| end | ||||
| end | ||||
| rescue | ||||
| raise | ||||
| ensure | ||||
| # make sure it unlock the directory | ||||
| dir.flock(File::LOCK_UN) | ||||
Jittat Fakcharoenphol
|
r96 | dir.close | ||
|
jittat
|
r71 | end | ||
| end | ||||
| # Check if I am the last one using the dir. If true, call block. | ||||
| def teardown | ||||
| dir = File.new(@dir_name) | ||||
| dir.flock(File::LOCK_EX) | ||||
| begin | ||||
| counter_filename = get_counter_filename | ||||
| if File.exist? counter_filename | ||||
| # someone is here | ||||
| f = File.new(counter_filename,"r+") | ||||
| counter = f.read.to_i | ||||
| f.seek(0) | ||||
| f.write("#{counter-1}\n") | ||||
| f.close | ||||
| if counter == 1 | ||||
| # i'm the last one | ||||
| File.delete(counter_filename) | ||||
| if block_given? | ||||
| yield | ||||
| end | ||||
| end | ||||
| else | ||||
| # This is BAD | ||||
| raise "Error: reference count missing" | ||||
| end | ||||
| rescue | ||||
| raise | ||||
| ensure | ||||
| # make sure it unlock the directory | ||||
| dir.flock(File::LOCK_UN) | ||||
|
Jittat Fakcharoenphol
|
r96 | dir.close | ||
|
jittat
|
r71 | end | ||
| end | ||||
| protected | ||||
| def get_counter_filename | ||||
| return File.join(@dir_name,@usage_filename) | ||||
| end | ||||
| end | ||||
| end | ||||