Add a Puppet::Util::Pidlock class, for use by locks and PID files

git-svn-id: https://reductivelabs.com/svn/puppet/trunk@2000 980ebf18-57e1-0310-9a29-db15c13687c0

1 files changed, 68 insertions, 0 deletions

diff --git a/lib/puppet/util/pidlock.rb b/lib/puppet/util/pidlock.rb
new file mode 100644
index 000000000..be7e1dbca
--- /dev/null
+++ b/lib/puppet/util/pidlock.rb
@@ -0,0 +1,68 @@
+require 'fileutils'
+
+class Puppet::Util::Pidlock
+	attr_reader :lockfile
+	
+	def initialize(lockfile)
+		@lockfile = lockfile
+	end
+	
+	def locked?
+		clear_if_stale
+		File.exists? @lockfile
+	end
+	
+	def mine?
+		Process.pid == lock_pid
+	end
+
+	def anonymous?
+		return false unless File.exists?(@lockfile)
+		File.read(@lockfile) == ""
+	end
+	
+	def lock(opts = {})
+		opts = {:anonymous => false}.merge(opts)
+
+		if locked?
+			false
+		else
+			if opts[:anonymous]
+				File.open(@lockfile, 'w') { |fd| true }
+			else
+				File.open(@lockfile, "w") { |fd| fd.write(Process.pid) }
+			end
+			true
+		end
+	end
+	
+	def unlock(opts = {})
+		opts = {:anonymous => false}.merge(opts)
+
+		if mine? or (opts[:anonymous] and anonymous?)
+			File.unlink(@lockfile)
+			true
+		else
+			false
+		end
+	end
+
+	private
+	def lock_pid
+		if File.exists? @lockfile
+			File.read(@lockfile).to_i
+		else
+			nil
+		end
+	end
+
+	def clear_if_stale
+		return if lock_pid.nil?
+		
+		begin
+			Process.kill(0, lock_pid)
+		rescue Errno::ESRCH
+			File.unlink(@lockfile)
+		end
+	end
+end