initial commit of lockit, sans tests

Author: Chris Beer

README.rdoc

@@ -1,6 +1,6 @@
 = lockit
 
-Description goes here.
+A ruby implementation of LockIt: A Simple File-based Convention for Resource Locking
 
 == Contributing to lockit
 

Rakefile

@@ -15,9 +15,8 @@ Jeweler::Tasks.new do |gem|
   gem.name = "lockit"
   gem.homepage = "http://github.com/cbeer/lockit"
   gem.license = "MIT"
-  gem.summary = %Q{TODO: one-line summary of your gem}
-  gem.description = %Q{TODO: longer description of your gem}
-  gem.email = "[email protected]"
+  gem.summary = "A ruby implementation of LockIt: A Simple File-based Convention for Resource Locking"
+  gem.email = "[email protected]"
   gem.authors = ["Chris Beer"]
   # Include your dependencies below. Runtime dependencies are required when using your gem,
   # and development dependencies are only needed for development (ie running rake tasks, tests, etc)

TODO

@@ -0,0 +1,3 @@
+- Can a process obtain a lock within a locked file system hierarchy?
+
+- "Once the lock release time has expired, that is, the current time is later than the release time, the lock file is considered stale." .. How should the library distinguish between stale + non-stale lock files? TRUE/FALSE/STALE?

bin/lockit

@@ -0,0 +1,27 @@
+#!/usr/bin/ruby
+require 'optparse'
+
+$LOAD_PATH.unshift File.join(File.dirname(__FILE__), '..', 'lib')
+require 'lockit'
+
+options = {}
+
+optparse = OptionParser.new do |opts|
+   opts.banner = "Usage: lockit [options] [dir]"
+
+   # This displays the help screen, all programs are
+   # assumed to have this option.
+   opts.on( '-h', '--help', 'Display this screen' ) do
+     puts opts
+     exit
+   end
+end
+
+optparse.parse!
+
+options[:dir] = ARGV.shift
+options[:dir] ||= Dir.pwd
+
+response = LockIt::Dir.new(options[:dir]).lock
+
+exit 1 unless response

bin/unlockit

@@ -0,0 +1,27 @@
+#!/usr/bin/ruby
+require 'optparse'
+
+$LOAD_PATH.unshift File.join(File.dirname(__FILE__), '..', 'lib')
+require 'lockit'
+
+options = {}
+
+optparse = OptionParser.new do |opts|
+   opts.banner = "Usage: unlock [options] [dir]"
+
+   # This displays the help screen, all programs are
+   # assumed to have this option.
+   opts.on( '-h', '--help', 'Display this screen' ) do
+     puts opts
+     exit
+   end
+end
+
+optparse.parse!
+
+options[:dir] = ARGV.shift
+options[:dir] ||= Dir.pwd
+
+response = LockIt::Dir.new(options[:dir]).unlock
+
+exit 1 unless response

lib/lockit.rb

@@ -0,0 +1,86 @@
+require 'fileutils'
+module LockIt
+  FILENAME='lock.txt'
+
+  module Mixin
+    def lock args = {}
+      return false if locked?
+      write_lock args
+      self
+    end
+
+    def revise_lock args
+      return false unless locked?
+      # xxx is it my lock to revise?
+      write_lock args
+      self
+    end
+
+    def try_lock args = {}
+      return false if locked?
+      lock args
+    end
+
+    def locked?
+      return true if closest_lock_file
+      false
+    end
+
+    def unlock
+      unlock!
+    end
+
+    def unlock!
+      FileUtils.rm lock_file
+    end
+
+    def lock_info
+      f = closest_lock_file
+      header, obtained, id, release = open(f).read.split("\n").first.split(" ")
+      info = {}
+      info[:file] = f
+      info[:obtained] = obtained
+      info[:id] = id
+      info[:release] = release if release
+
+      info
+    end
+
+    private
+    def closest_lock_file
+      d = []
+      last = nil
+      while pwd = File.expand_path(File.join([self.path, d].flatten)) and pwd != last
+        f =  File.join(pwd, LockIt::FILENAME)
+	return f if File.exists? f
+	d << '..'
+        last = pwd
+      end
+      return false 
+    end
+
+    def lock_file
+      File.join(self.path, LockIt::FILENAME)
+    end
+    def write_lock args
+      File.open(lock_file, 'w') do |f|
+        f.write(lock_content(args))
+      end
+    end
+
+    def lock_content args
+      s = "Lock: #{Time.now.utc.strftime("%Y-%m-%dT%H:%M:%S+00:00")} #{uniqid}"
+      s += " #{args[:release].utc.strftime("%Y-%m-%dT%H:%M:%S+00:00")}" if args[:release] and args[:release].respond_to? :utc
+    end
+
+    def uniqid
+      Process.pid
+    end
+
+  end
+
+
+  class Dir < ::Dir
+    include LockIt::Mixin
+  end
+end