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Contents
module Opener
module Daemons
##
# Class for writing and retrieving PID files as well as managing the
# associated process.
#
# @!attribute [r] path
# The path to store the PID in.
# @return [String]
#
class Pidfile
attr_reader :path
##
# @param [String] path
#
def initialize(path)
@path = path
end
##
# Writes the given process ID to `@path`.
#
# @param [Fixnum] id
#
def write(id)
File.open(path, 'w') do |handle|
handle.write(id.to_s)
end
# Kill the process immediately if we couldn't write the PID
rescue Errno::ENOENT, Errno::EPERM => error
Process.kill('KILL', id)
end
##
# Reads and returns the process ID.
#
# @return [Fixnum]
#
def read
return File.read(path).to_i
end
##
# Removes the associated file, if it exists.
#
def unlink
File.unlink(path) if File.file?(path)
end
##
# Terminates the process by sending it the TERM signal and waits for it to
# shut down.
#
def terminate
id = read
begin
Process.kill('TERM', id)
Process.wait(id)
rescue Errno::ESRCH, Errno::ECHILD
# Process terminated, yay. Any other error is re-raised.
end
end
##
# Returns `true` if the associated process is alive.
#
# @return [TrueClass|FalseClass]
#
def alive?
id = read
begin
Process.kill(0, id)
return true
rescue Errno::ESRCH, Errno::EPERM
return false
end
end
end # Pidfile
end # Daemons
end # Opener
Version data entries
34 entries across 34 versions & 1 rubygems