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169 lines
2.7 KiB
Ruby
169 lines
2.7 KiB
Ruby
module Demon; end
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# intelligent fork based demonizer
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class Demon::Base
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def self.start(count=1)
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@demons ||= {}
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count.times do |i|
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(@demons["#{prefix}_#{i}"] ||= new(i)).start
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end
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end
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def self.stop
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return unless @demons
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@demons.values.each do |demon|
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demon.stop
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end
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end
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def self.restart
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return unless @demons
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@demons.values.each do |demon|
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demon.stop
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demon.start
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end
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end
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def self.ensure_running
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@demons.values.each do |demon|
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demon.ensure_running
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end
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end
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def initialize(index)
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@index = index
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@pid = nil
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@parent_pid = Process.pid
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@started = false
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end
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def pid_file
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"#{Rails.root}/tmp/pids/#{self.class.prefix}_#{@index}.pid"
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end
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def stop
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@started = false
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if @pid
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Process.kill("HUP",@pid)
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@pid = nil
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@started = false
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end
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end
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def ensure_running
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return unless @started
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if !@pid
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@started = false
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start
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return
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end
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dead = Process.waitpid(@pid, Process::WNOHANG) rescue -1
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if dead
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STDERR.puts "Detected dead worker #{@pid}, restarting..."
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@pid = nil
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@started = false
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start
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end
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end
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def start
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return if @pid || @started
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if existing = already_running?
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# should not happen ... so kill violently
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STDERR.puts "Attempting to kill pid #{existing}"
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Process.kill("TERM",existing)
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end
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@started = true
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run
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end
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def run
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if @pid = fork
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write_pid_file
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return
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end
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monitor_parent
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establish_app
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after_fork
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end
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def already_running?
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if File.exists? pid_file
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pid = File.read(pid_file).to_i
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if alive?(pid)
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return pid
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end
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end
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nil
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end
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private
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def write_pid_file
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FileUtils.mkdir_p(Rails.root + "tmp/pids")
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File.open(pid_file,'w') do |f|
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f.write(@pid)
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end
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end
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def delete_pid_file
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File.delete(pid_file)
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end
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def monitor_parent
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Thread.new do
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while true
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unless alive?(@parent_pid)
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Process.kill "TERM", Process.pid
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sleep 10
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Process.kill "KILL", Process.pid
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end
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sleep 1
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end
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end
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end
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def alive?(pid)
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begin
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Process.kill(0, pid)
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true
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rescue
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false
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end
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end
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def suppress_stdout
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true
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end
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def suppress_stderr
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true
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end
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def establish_app
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Discourse.after_fork
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Signal.trap("HUP") do
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begin
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delete_pid_file
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ensure
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# TERM is way cleaner than exit
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Process.kill("TERM", Process.pid)
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end
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end
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# keep stuff simple for now
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$stdout.reopen("/dev/null", "w") if suppress_stdout
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$stderr.reopen("/dev/null", "w") if suppress_stderr
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end
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def after_fork
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end
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end
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