Class: Yahns::Server

Inherits:
Object
  • Object
show all
Includes:
SocketHelper
Defined in:
lib/yahns/server.rb

Overview

:nodoc:

Constant Summary collapse

QUEUE_SIGS = 
[ :WINCH, :QUIT, :INT, :TERM, :USR1, :USR2, :HUP, :TTIN, :TTOU,
:CHLD ]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from SocketHelper

#bind_listen, #log_buffer_sizes, #new_tcp_server, #server_cast, #set_server_sockopt, #so_reuseport, #sock_name, #tcp_name

Constructor Details

#initialize(config) ⇒ Server

Returns a new instance of Server.



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# File 'lib/yahns/server.rb', line 22

def initialize(config)
  @shutdown_expire = nil
  @shutdown_timeout = nil
  @reexec_pid = 0
  @daemon_pipe = nil # writable IO or true
  @config = config
  @workers = {} # pid -> workers
  @sig_queue = [] # nil in forked workers
  @logger = Logger.new($stderr)
  @sev = Yahns::Sigevent.new
  @listeners = []
  @pid = nil
  @worker_processes = nil
  @before_exec = nil
  @atfork_prepare = @atfork_parent = @atfork_child = nil
  @user = nil
  @queues = []
  @wthr = []
end

Instance Attribute Details

#atfork_child=(value) ⇒ Object (writeonly)

Sets the attribute atfork_child

Parameters:

  • value —

    the value to set the attribute atfork_child to.



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# File 'lib/yahns/server.rb', line 19

def atfork_child=(value)
  @atfork_child = value
end

#atfork_parent=(value) ⇒ Object (writeonly)

Sets the attribute atfork_parent

Parameters:

  • value —

    the value to set the attribute atfork_parent to.



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# File 'lib/yahns/server.rb', line 18

def atfork_parent=(value)
  @atfork_parent = value
end

#atfork_prepare=(value) ⇒ Object (writeonly)

Sets the attribute atfork_prepare

Parameters:

  • value —

    the value to set the attribute atfork_prepare to.



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# File 'lib/yahns/server.rb', line 17

def atfork_prepare=(value)
  @atfork_prepare = value
end

#before_exec=(value) ⇒ Object (writeonly)

Sets the attribute before_exec

Parameters:

  • value —

    the value to set the attribute before_exec to.



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# File 'lib/yahns/server.rb', line 14

def before_exec=(value)
  @before_exec = value
end

#daemon_pipe ⇒ Object

Returns the value of attribute daemon_pipe.



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# File 'lib/yahns/server.rb', line 11

def daemon_pipe
  @daemon_pipe
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/yahns/server.rb', line 12

def logger
  @logger
end

#shutdown_timeout=(value) ⇒ Object (writeonly)

Sets the attribute shutdown_timeout

Parameters:

  • value —

    the value to set the attribute shutdown_timeout to.



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# File 'lib/yahns/server.rb', line 16

def shutdown_timeout=(value)
  @shutdown_timeout = value
end

#user=(value) ⇒ Object (writeonly)

Sets the attribute user

Parameters:

  • value —

    the value to set the attribute user to.



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# File 'lib/yahns/server.rb', line 13

def user=(value)
  @user = value
end

#worker_processes=(value) ⇒ Object (writeonly)

Sets the attribute worker_processes

Parameters:

  • value —

    the value to set the attribute worker_processes to.



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# File 'lib/yahns/server.rb', line 15

def worker_processes=(value)
  @worker_processes = value
end

Instance Method Details

#bind_new_listeners! ⇒ Object

call only after calling inherit_listeners! This binds any listeners we did NOT inherit from the parent

Raises:

  • (ArgumentError) 


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# File 'lib/yahns/server.rb', line 329

def bind_new_listeners!
  self.listeners = @config.config_listeners.keys
  raise ArgumentError, "no listeners" if @listeners.empty?
end

#clobber_pid(path) ⇒ Object 



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# File 'lib/yahns/server.rb', line 120

def clobber_pid(path)
  unlink_pid_safe(@pid) if @pid
  if path
    fp = begin
      tmp = "#{File.dirname(path)}/#{rand}.#$$"
      File.open(tmp, File::RDWR|File::CREAT|File::EXCL, 0644)
    rescue Errno::EEXIST
      retry
    end
    fp.syswrite("#$$\n")
    File.rename(fp.path, path)
    fp.close
  end
end

#daemon_ready ⇒ Object 



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# File 'lib/yahns/server.rb', line 204

def daemon_ready
  @daemon_pipe.respond_to?(:syswrite) or return
  begin
    @daemon_pipe.syswrite("#$$")
  rescue => e
    @logger.warn("grandparent died too soon?: #{e.message} (#{e.class})")
  end
  @daemon_pipe.close
  @daemon_pipe = true # for SIGWINCH
end

#drop_acceptors ⇒ Object 



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# File 'lib/yahns/server.rb', line 82

def drop_acceptors
  @listeners.delete_if(&:ac_quit)
end

#dropping(fdmap) ⇒ Object 



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# File 'lib/yahns/server.rb', line 467

def dropping(fdmap)
  if drop_acceptors[0] || fdmap.size > 0
    timeout = @shutdown_expire < Time.now ? -1 : @shutdown_timeout
    fdmap.desperate_expire(timeout)
    true
  else
    false
  end
end

#fdmap_init ⇒ Object

spins up processing threads of the server



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# File 'lib/yahns/server.rb', line 349

def fdmap_init
  thresh = @config.value(:client_expire_threshold)

  # keeps track of all connections, like ObjectSpace, but only for IOs
  fdmap = Yahns::Fdmap.new(@logger, thresh)

  # once initialize queues (epoll/kqueue) and associated worker threads
  queues = {}

  # spin up applications (which are preload: false)
  @config.app_ctx.each(&:after_fork_init)

  @shutdown_timeout ||= @config.app_ctx.map(&:client_timeout).max

  # spin up acceptor threads, clients flow into worker queues after this
  @listeners.each do |l|
    opts = sock_opts(l)
    ctx = opts[:yahns_app_ctx]
    ctx_list = opts[:yahns_app_ctx_list] ||= []
    qegg = ctx.qegg || @config.qeggs[:default]
    ctx.queue = queues[qegg] ||= qegg_vivify(qegg, fdmap)
    ctx = ctx.dup
    ctx.__send__(:include, l.expire_mod)
    ctx_list << ctx
    # acceptors feed the the queues
    l.spawn_acceptor(opts[:threads] || 1, @logger, ctx)
  end
  fdmap
end

#inherit_listeners! ⇒ Object 



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# File 'lib/yahns/server.rb', line 305

def inherit_listeners!
  # inherit sockets from parents, they need to be plain Socket objects
  # before they become Yahns::UNIXServer or Yahns::TCPServer
  #
  # Note: we intentionally use a yahns-specific environment variable
  # here because existing servers may use non-blocking listen sockets.
  # yahns uses _blocking_ listen sockets exclusively.  We cannot
  # change an existing socket to blocking mode if two servers are
  # running (one expecting blocking, one expecting non-blocking)
  # because that can completely break the non-blocking one.
  # Unfortunately, there is no one-off MSG_DONTWAIT-like flag for
  # accept4(2).
  inherited = ENV['YAHNS_FD'].to_s.split(/,/).map do |fd|
    io = Socket.for_fd(fd.to_i)
    set_server_sockopt(io, sock_opts(io))
    @logger.info "inherited addr=#{sock_name(io)} fd=#{fd}"
    server_cast(io)
  end

  @listeners.replace(inherited)
end

#join ⇒ Object

single-threaded only, this is overriden if @worker_processes is non-nil



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# File 'lib/yahns/server.rb', line 478

def join
  daemon_ready
  fdmap = fdmap_init
  alive = true
  begin
    alive = sp_sig_handle(alive)
  rescue => e
    Yahns::Log.exception(@logger, "main loop", e)
  end while alive || dropping(fdmap)
  unlink_pid_safe(@pid) if @pid
ensure
  quit_finish
end

#listen(address) ⇒ Object

add a given address to the listeners set, idempotently Allows workers to add a private, per-process listener via the after_fork hook. Very useful for debugging and testing. :tries may be specified as an option for the number of times to retry, and :delay may be specified as the time in seconds to delay between retries. A negative value for :tries indicates the listen will be retried indefinitely, this is useful when workers belonging to different masters are spawned during a transparent upgrade.



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# File 'lib/yahns/server.rb', line 174

def listen(address)
  address = @config.expand_addr(address)
  return if String === address && listener_names.include?(address)
  delay = 0.5
  tries = 5

  begin
    io = bind_listen(address, sock_opts(address))
    unless Yahns::TCPServer === io || Yahns::UNIXServer === io
      io = server_cast(io)
    end
    @logger.info "listening on addr=#{sock_name(io)} fd=#{io.fileno}"
    @listeners << io
    io
  rescue Errno::EADDRINUSE => err
    if tries == 0
      @logger.error "adding listener failed addr=#{address} (in use)"
      raise err
    end
    tries -= 1
    @logger.warn "retrying in #{delay} seconds " \
                 "(#{tries < 0 ? 'infinite' : tries} tries left)"
    sleep(delay)
    retry
  rescue => err
    @logger.fatal "error adding listener addr=#{address}"
    raise err
  end
end

#listener_names(listeners = @listeners) ⇒ Object

returns an array of string names for the given listener array



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# File 'lib/yahns/server.rb', line 297

def listener_names(listeners = @listeners)
  listeners.map { |io| sock_name(io) }
end

#listeners=(listeners) ⇒ Object

replaces current listener set with listeners. This will close the socket if it will not exist in the new listener set



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# File 'lib/yahns/server.rb', line 88

def listeners=(listeners)
  cur_names, dead_names = [], []
  listener_names.each do |name|
    if ?/ == name[0]
      # mark unlinked sockets as dead so we can rebind them
      (File.socket?(name) ? cur_names : dead_names) << name
    else
      cur_names << name
    end
  end
  set_names = listener_names(listeners)
  dead_names.concat(cur_names - set_names).uniq!
  dying = []
  @listeners.delete_if do |io|
    if dead_names.include?(sock_name(io))
      if io.ac_quit
        true
      else
        dying << io
        false
      end
    else
      set_server_sockopt(io, sock_opts(io))
      false
    end
  end

  dying.delete_if(&:ac_quit) while dying[0]

  (set_names - cur_names).each { |addr| listen(addr) }
end

#load_config! ⇒ Object 



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# File 'lib/yahns/server.rb', line 284

def load_config!
  @logger.info "reloading config_file=#{@config.config_file}"
  @config.config_reload!
  @config.commit!(self)
  soft_kill_each_worker("QUIT")
  Yahns::Log.reopen_all
  @logger.info "done reloading config_file=#{@config.config_file}"
rescue StandardError, LoadError, SyntaxError => e
  Yahns::Log.exception(@logger,
                   "error reloading config_file=#{@config.config_file}", e)
end

#pid=(path) ⇒ Object

sets the path for the PID file of the master process



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# File 'lib/yahns/server.rb', line 136

def pid=(path)
  if path
    if x = valid_pid?(path)
      return path if @pid && path == @pid && x == $$
      if x == @reexec_pid && @pid =~ /\.oldbin\z/
        @logger.warn("will not set pid=#{path} while reexec-ed "\
                     "child is running PID:#{x}")
        return
      end
      raise ArgumentError, "Already running on PID:#{x} " \
                           "(or pid=#{path} is stale)"
    end
  end

  # rename the old pid if possible
  if @pid && path
    begin
      File.rename(@pid, path)
    rescue Errno::ENOENT, Errno::EXDEV
      # a user may have accidentally removed the original,
      # obviously cross-FS renames don't work, either.
      clobber_pid(path)
    end
  else
    clobber_pid(path)
  end
  @pid = path
end

#proc_name(tag) ⇒ Object 



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# File 'lib/yahns/server.rb', line 334

def proc_name(tag)
  s = Yahns::START
  $0 = ([ File.basename(s[0]), tag ]).concat(s[:argv]).join(' ')
end

#qegg_vivify(qegg, fdmap) ⇒ Object 



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# File 'lib/yahns/server.rb', line 339

def qegg_vivify(qegg, fdmap)
  queue = qegg.vivify(fdmap)
  qegg.worker_threads.times do
    @wthr << queue.worker_thread(@logger, qegg.max_events)
  end
  @queues << queue
  queue
end

#quit_enter(alive) ⇒ Object 



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# File 'lib/yahns/server.rb', line 385

def quit_enter(alive)
  if alive
    @logger.info("gracefully exiting shutdown_timeout=#@shutdown_timeout")
    @shutdown_expire ||= Time.now + @shutdown_timeout + 1
  else # drop connections immediately if signaled twice
    @logger.info("graceful exit aborted, exiting immediately")
    # we will still call any app-defined at_exit hooks here
    # use SIGKILL if you don't want that.
    exit(0)
  end

  drop_acceptors # stop acceptors, we close epolls in quit_done
  @config.config_listeners.each_value do |opts|
    list= opts[:yahns_app_ctx_list] or next
    # Yahns::HttpContext#persistent_connections=
    list.each { |ctx| ctx.persistent_connections = false }
  end
  false
end

#quit_finish ⇒ Object

drops all the the IO objects we have threads waiting on before exiting This just injects the QueueQuitter object which acts like a monkey wrench thrown into a perfectly good engine :)



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# File 'lib/yahns/server.rb', line 408

def quit_finish
  quitter = Yahns::QueueQuitter.new

  # throw the monkey wrench into the worker threads
  @queues.each { |q| q.queue_add(quitter, Yahns::Queue::QEV_QUIT) }

  # watch the monkey wrench destroy all the threads!
  # Ugh, this may fail if we have dedicated threads trickling
  # response bodies out (e.g. "tail -F")  Oh well, have a timeout
  begin
    @wthr.delete_if { |t| t.join(0.01) }
  end while @wthr[0] && Time.now <= @shutdown_expire

  # cleanup, our job is done
  @queues.each(&:close).clear

  # we must not let quitter get GC-ed if we have any worker threads leftover
  @wthr.each { |t| t[:yahns_quitter] = quitter }

  quitter.close
rescue => e
  Yahns::Log.exception(@logger, "quit finish", e)
ensure
  if (@wthr.size + @listeners.size) > 0
    @logger.warn("still active wthr=#{@wthr.size} "\
                 "listeners=#{@listeners.size}")
  end
end

#reap_reexec ⇒ Object 



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# File 'lib/yahns/server.rb', line 437

def reap_reexec
  @reexec_pid > 0 or return
  wpid, status = Process.waitpid2(@reexec_pid, Process::WNOHANG)
  wpid or return
  @logger.error "reaped #{status.inspect} exec()-ed"
  @reexec_pid = 0
  self.pid = @pid.chomp('.oldbin') if @pid
end

#reexec ⇒ Object

reexecutes the Yahns::START with a new binary



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# File 'lib/yahns/server.rb', line 216

def reexec
  if @reexec_pid > 0
    begin
      Process.kill(0, @reexec_pid)
      @logger.error "reexec-ed child already running PID:#@reexec_pid"
      return
    rescue Errno::ESRCH
      @reexec_pid = 0
    end
  end

  if @pid
    old_pid = "#@pid.oldbin"
    begin
      self.pid = old_pid  # clear the path for a new pid file
    rescue ArgumentError
      @logger.error "old PID:#{valid_pid?(old_pid)} running with " \
                    "existing pid=#{old_pid}, refusing rexec"
      return
    rescue => e
      @logger.error "error writing pid=#{old_pid} #{e.class} #{e.message}"
      return
    end
  end

  # We cannot use Process.spawn here because of redirects + close-on-exec
  # We must keep close_on_exec=true in the parent process and only set
  # close_on_exec=false in the child.  There must be no opportunity
  # for the user app to ever get a listen socket with close_on_exec=false
  @reexec_pid = fork do
    redirects = {}
    @listeners.each do |sock|
      sock.close_on_exec = false
      redirects[sock.fileno] = sock
    end
    ENV['YAHNS_FD'] = redirects.keys.join(',')
    redirects[:close_others] = true
    Dir.chdir(@config.value(:working_directory) || Yahns::START[:cwd])
    cmd = [ Yahns::START[0] ].concat(Yahns::START[:argv])
    @logger.info "executing #{cmd.inspect} (in #{Dir.pwd})"
    @before_exec.call(cmd) if @before_exec
    cmd << redirects
    exec(*cmd)
  end
end

#sock_opts(io) ⇒ Object 



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# File 'lib/yahns/server.rb', line 301

def sock_opts(io)
  @config.config_listeners[sock_name(io)]
end

#sp_sig_handle(alive) ⇒ Object 



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# File 'lib/yahns/server.rb', line 446

def sp_sig_handle(alive)
  @sev.kgio_wait_readable(alive ? nil : 0.01)
  @sev.yahns_step
  case sig = @sig_queue.shift
  when :QUIT, :TERM, :INT
    return quit_enter(alive)
  when :CHLD
    reap_reexec
  when :USR1
    usr1_reopen('')
  when :USR2
    reexec
  when :HUP
    reexec
    return quit_enter(alive)
  when :TTIN, :TTOU, :WINCH
    @logger.info("SIG#{sig} ignored in single-process mode")
  end
  alive
end

#sqwakeup(sig) ⇒ Object 



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# File 'lib/yahns/server.rb', line 42

def sqwakeup(sig)
  @sig_queue << sig
  @sev.sev_signal
end

#start ⇒ Object 



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# File 'lib/yahns/server.rb', line 47

def start
  @config.commit!(self)
  inherit_listeners!
  # we try inheriting listeners first, so we bind them later.
  # we don't write the pid file until we've bound listeners in case
  # yahns was started twice by mistake.

  # setup signal handlers before writing pid file in case people get
  # trigger happy and send signals as soon as the pid file exists.
  QUEUE_SIGS.each { |sig| trap(sig) { sqwakeup(sig) } }
  bind_new_listeners!
  self.pid = @config.value(:pid) # write pid file
  if @worker_processes
    require 'yahns/server_mp'
    extend Yahns::ServerMP
  else
    switch_user(*@user) if @user
  end
  self
end

#switch_user(user, group = nil) ⇒ Object 



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# File 'lib/yahns/server.rb', line 68

def switch_user(user, group = nil)
  # we do not protect the caller, checking Process.euid == 0 is
  # insufficient because modern systems have fine-grained
  # capabilities.  Let the caller handle any and all errors.
  uid = Etc.getpwnam(user).uid
  gid = Etc.getgrnam(group).gid if group
  Yahns::Log.chown_all(uid, gid)
  if gid && Process.egid != gid
    Process.initgroups(user, gid)
    Process::GID.change_privilege(gid)
  end
  Process.euid != uid and Process::UID.change_privilege(uid)
end

#unlink_pid_safe(path) ⇒ Object

unlinks a PID file at given path if it contains the current PID still potentially racy without locking the directory (which is non-portable and may interact badly with other programs), but the window for hitting the race condition is small



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# File 'lib/yahns/server.rb', line 266

def unlink_pid_safe(path)
  (File.read(path).to_i == $$ and File.unlink(path)) rescue nil
end

#usr1_reopen(prefix) ⇒ Object 



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# File 'lib/yahns/server.rb', line 379

def usr1_reopen(prefix)
  @logger.info "#{prefix}reopening logs..."
  Yahns::Log.reopen_all
  @logger.info "#{prefix}done reopening logs"
end

#valid_pid?(path) ⇒ Boolean

returns a PID if a given path contains a non-stale PID file, nil otherwise.

Returns:

  • (Boolean) 


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# File 'lib/yahns/server.rb', line 272

def valid_pid?(path)
  wpid = File.read(path).to_i
  wpid <= 0 and return
  Process.kill(0, wpid)
  wpid
rescue Errno::EPERM
  @logger.info "pid=#{path} possibly stale, got EPERM signalling PID:#{wpid}"
  nil
rescue Errno::ESRCH, Errno::ENOENT
  # don't unlink stale pid files, racy without non-portable locking...
end