Module: Einhorn

Defined in:
lib/einhorn.rb,
lib/einhorn/event.rb,
lib/einhorn/prctl.rb,
lib/einhorn/third.rb,
lib/einhorn/client.rb,
lib/einhorn/compat.rb,
lib/einhorn/worker.rb,
lib/einhorn/command.rb,
lib/einhorn/version.rb,
lib/einhorn/prctl_linux.rb,
lib/einhorn/worker_pool.rb

Defined Under Namespace

Modules: AbstractState, Command, Compat, Event, PrctlRaw, State, Third, TransientState, Worker, WorkerPool Classes: Client, PrctlAbstract, PrctlLinux, PrctlUnimplemented

Constant Summary collapse

Prctl = 
PrctlUnimplemented
VERSION = 
'0.8.2'

Class Method Summary collapse

Class Method Details

.bind(addr, port, flags) ⇒ Object 



148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
 
# File 'lib/einhorn.rb', line 148

def self.bind(addr, port, flags)
  log_info("Binding to #{addr}:#{port} with flags #{flags.inspect}")
  sd = Socket.new(Socket::AF_INET, Socket::SOCK_STREAM, 0)
  Einhorn::Compat.cloexec!(sd, false)

  if flags.include?('r') || flags.include?('so_reuseaddr')
    sd.setsockopt(Socket::SOL_SOCKET, Socket::SO_REUSEADDR, 1)
  end

  sd.bind(Socket.pack_sockaddr_in(port, addr))
  sd.listen(Einhorn::State.config[:backlog])

  if flags.include?('n') || flags.include?('o_nonblock')
    fl = sd.fcntl(Fcntl::F_GETFL)
    sd.fcntl(Fcntl::F_SETFL, fl | Fcntl::O_NONBLOCK)
  end

  Einhorn::TransientState.socket_handles << sd
  [sd.fileno, sd.local_address.ip_port]
end

.can_safely_reload? ⇒ Boolean

Returns true if a reload of the einhorn master via re-execing is not likely to be completely unsafe (that is, the new process’s environment won’t prevent it from loading its code on exec).

Returns:

  • (Boolean) 


374
375
376
377
378
379
380
381
382
 
# File 'lib/einhorn.rb', line 374

def self.can_safely_reload?
  upgrade_sentinel = fork do
    Einhorn::TransientState.whatami = :upgrade_sentinel
    Einhorn.initialize_reload_environment
    Einhorn::Compat.exec(*Einhorn.upgrade_commandline(['--upgrade-check']))
  end
  Process.wait(upgrade_sentinel)
  $?.exitstatus.zero?
end

.dump_environment_info ⇒ Object

Log info about the environment as observed by ruby on startup. Currently, this means the bundler and rbenv versions.



401
402
403
404
405
406
407
408
409
 
# File 'lib/einhorn.rb', line 401

def self.dump_environment_info
  log_info("Running under Ruby #{RUBY_VERSION}", :environment)
  log_info("Rbenv ruby version: #{ENV['RBENV_VERSION']}", :environment) if ENV['RBENV_VERSION']
  begin
    bundler_gem = Gem::Specification.find_by_name('bundler')
    log_info("Using Bundler #{bundler_gem.version.to_s}", :environment)
  rescue Gem::LoadError
  end
end

.initialize_reload_environment ⇒ Object

Set up the environment for reloading the einhorn master:

  1. Clear the current process’s environment,

  2. Set it to the environmment at startup

  3. Delete all variables marked to be dropped via ‘–drop-env-var`

This method is safe to call in the master only before ‘exec`ing something.



391
392
393
394
395
396
397
 
# File 'lib/einhorn.rb', line 391

def self.initialize_reload_environment
  ENV.clear
  ENV.update(Einhorn::TransientState.environ)
  Einhorn::State.drop_environment_variables.each do |var|
    ENV.delete(var)
  end
end

.is_script(file) ⇒ Object

Not really a thing, but whatever.



221
222
223
224
225
226
 
# File 'lib/einhorn.rb', line 221

def self.is_script(file)
  File.open(file) do |f|
    bytes = f.read(2)
    bytes == '#!'
  end
end

.log_debug(msg, tag = nil) ⇒ Object

Implement these ourselves so it plays nicely with state persistence



170
171
172
173
174
 
# File 'lib/einhorn.rb', line 170

def self.log_debug(msg, tag=nil)
  $stderr.puts("#{log_tag} DEBUG: #{msg}\n") if Einhorn::State.verbosity <= 0
  $stderr.flush
  self.send_tagged_message(tag, msg) if tag
end

.log_error(msg, tag = nil) ⇒ Object 



180
181
182
183
184
 
# File 'lib/einhorn.rb', line 180

def self.log_error(msg, tag=nil)
  $stderr.puts("#{log_tag} ERROR: #{msg}\n") if Einhorn::State.verbosity <= 2
  $stderr.flush
  self.send_tagged_message(tag, "ERROR: #{msg}") if tag
end

.log_info(msg, tag = nil) ⇒ Object 



175
176
177
178
179
 
# File 'lib/einhorn.rb', line 175

def self.log_info(msg, tag=nil)
  $stderr.puts("#{log_tag} INFO: #{msg}\n") if Einhorn::State.verbosity <= 1
  $stderr.flush
  self.send_tagged_message(tag, msg) if tag
end

.master_ps_name ⇒ Object 



302
303
304
 
# File 'lib/einhorn.rb', line 302

def self.master_ps_name
  "einhorn: #{worker_ps_name}"
end

.preload ⇒ Object 



228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
 
# File 'lib/einhorn.rb', line 228

def self.preload
  if path = Einhorn::State.path
    set_argv(Einhorn::State.cmd, false)

    begin
      # Reset preloaded state to false - this allows us to monitor for failed preloads during reloads.
      Einhorn::State.preloaded = false
      # If it's not going to be requireable, then load it.
      if !path.end_with?('.rb') && File.exists?(path)
        log_info("Loading #{path} (if this hangs, make sure your code can be properly loaded as a library)", :upgrade)
        load path
      else
        log_info("Requiring #{path} (if this hangs, make sure your code can be properly loaded as a library)", :upgrade)
        require path

        force_move_to_oldgen if Einhorn::State.config[:gc_before_fork]
      end
    rescue Exception => e
      log_info("Proceeding with postload -- could not load #{path}: #{e} (#{e.class})\n  #{e.backtrace.join("\n  ")}", :upgrade)
    else
      if defined?(einhorn_main)
        log_info("Successfully loaded #{path}", :upgrade)
        Einhorn::State.preloaded = true
      else
        log_info("Proceeding with postload -- loaded #{path}, but no einhorn_main method was defined", :upgrade)
      end
    end
  end
end

.print_state ⇒ Object 



144
145
146
 
# File 'lib/einhorn.rb', line 144

def self.print_state
  log_info(Einhorn::State.state.pretty_inspect)
end

.renice_self ⇒ Object 



310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
 
# File 'lib/einhorn.rb', line 310

def self.renice_self
  whatami = Einhorn::TransientState.whatami
  return unless nice = Einhorn::State.nice[whatami]
  pid = $$

  unless nice.kind_of?(Fixnum)
    raise "Nice must be a fixnum: #{nice.inspect}"
  end

  # Explicitly don't shellescape the renice command
  cmd = "#{Einhorn::State.nice[:renice_cmd]} #{nice} -p #{pid}"
  log_info("Running #{cmd.inspect} to renice self to level #{nice}")
  `#{cmd}`
  unless $?.exitstatus == 0
    # TODO: better error handling?
    log_error("Renice command exited with status: #{$?.inspect}, but continuing on anyway.")
  end
end

.restore_state(state) ⇒ Object 



93
94
95
96
97
98
99
100
101
 
# File 'lib/einhorn.rb', line 93

def self.restore_state(state)
  parsed = YAML.load(state)
  updated_state, message = update_state(Einhorn::State, "einhorn", parsed[:state])
  Einhorn::State.state = updated_state
  Einhorn::Event.restore_persistent_descriptors(parsed[:persistent_descriptors])
  # Do this after setting state so verbosity is right
  Einhorn.log_info("Using loaded state: #{parsed.inspect}")
  Einhorn.log_info(message) if message
end

.run ⇒ Object 



411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
 
# File 'lib/einhorn.rb', line 411

def self.run
  Einhorn::Command::Interface.init
  Einhorn::Event.init

  unless Einhorn::TransientState.stateful
    if Einhorn::State.config[:number] < 1
      log_error("You need to spin up at least at least 1 copy of the process")
      return
    end
    Einhorn::Command::Interface.persistent_init

    Einhorn::State.orig_cmd = ARGV.dup
    Einhorn::State.cmd = ARGV.dup
    # TODO: don't actually alter ARGV[0]?
    Einhorn::State.cmd[0] = which(Einhorn::State.cmd[0])
    socketify_env!
    socketify!(Einhorn::State.cmd)
  end

  set_master_ps_name
  renice_self
  preload

  # In the middle of upgrading
  if Einhorn::State.reloading_for_upgrade
    Einhorn::Command.upgrade_workers
    Einhorn::State.reloading_for_upgrade = false
  end

  # If setting a signal-timeout, timeout the event loop
  # in the same timeframe, ensuring processes are culled
  # on a regular basis.
  if Einhorn::State.signal_timeout
    Einhorn::Event.default_timeout = Einhorn::Event.default_timeout.nil? ?
      Einhorn::State.signal_timeout : [Einhorn::State.signal_timeout, Einhorn::Event.default_timeout].min
  end

  while Einhorn::State.respawn || Einhorn::State.children.size > 0
    log_debug("Entering event loop")

    # All of these are non-blocking
    Einhorn::Command.reap
    Einhorn::Command.replenish
    Einhorn::Command.cull

    # Make sure to do this last, as it's blocking.
    Einhorn::Event.loop_once
  end
end

.send_tagged_message(tag, message, last = false) ⇒ Object 



186
187
188
 
# File 'lib/einhorn.rb', line 186

def self.send_tagged_message(tag, message, last=false)
  Einhorn::Command::Interface.send_tagged_message(tag, message, last)
end

.set_argv(cmd, set_ps_name) ⇒ Object 



274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
 
# File 'lib/einhorn.rb', line 274

def self.set_argv(cmd, set_ps_name)
  # TODO: clean up this hack
  idx = 0
  if cmd[0] =~ /(^|\/)ruby$/
    idx = 1
  elsif !is_script(cmd[0])
    log_info("WARNING: Going to set $0 to #{cmd[idx]}, but it doesn't look like a script")
  end

  if set_ps_name
    # Note this will mess up $0 if we try using it in our code, but
    # we don't so that's basically ok. It's a bit annoying that this
    # is how Ruby exposes changing the output of ps. Note that Ruby
    # doesn't seem to shrink your cmdline buffer, so ps just ends up
    # having lots of trailing spaces if we set $0 to something
    # short. In the future, we could try to not pass einhorn's
    # state in ARGV.
    $0 = worker_ps_name
  end

  ARGV[0..-1] = cmd[idx+1..-1]
  log_info("Set#{set_ps_name ? " $0 = #{$0.inspect}, " : nil} ARGV = #{ARGV.inspect}")
end

.set_master_ps_name ⇒ Object 



298
299
300
 
# File 'lib/einhorn.rb', line 298

def self.set_master_ps_name
  $0 = master_ps_name
end

.socketify!(cmd) ⇒ Object

This duplicates some code from the environment path, but is deprecated so that’s ok.



339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
 
# File 'lib/einhorn.rb', line 339

def self.socketify!(cmd)
  cmd.map! do |arg|
    if arg =~ /^(.*=|)srv:([^:]+):(\d+)((?:,\w+)*)$/
      log_error("Using deprecated command-line configuration for Einhorn; should upgrade to the environment variable interface.")
      opt = $1
      host = $2
      port = $3
      flags = $4.split(',').select {|flag| flag.length > 0}.map {|flag| flag.downcase}
      Einhorn::State.sockets[[host, port]] ||= bind(host, port, flags)[0]
      fd = Einhorn::State.sockets[[host, port]]
      "#{opt}#{fd}"
    else
      arg
    end
  end
end

.socketify_env! ⇒ Object 



329
330
331
332
333
334
335
 
# File 'lib/einhorn.rb', line 329

def self.socketify_env!
  Einhorn::State.bind.each do |host, port, flags|
    fd, actual_port = bind(host, port, flags)
    Einhorn::State.bind_fds << fd
    Einhorn::State.bound_ports << actual_port
  end
end

.update_state(store, store_name, old_state) ⇒ Object 



103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
 
# File 'lib/einhorn.rb', line 103

def self.update_state(store, store_name, old_state)
  message = []
  updated_state = old_state.dup

  # Handle changes in state format updates from previous einhorn versions
  if store == Einhorn::State && updated_state[:children]
    # Depending on what is passed for --reexec-as, it's possible
    # that the process received a SIGCHLD while something other
    # than einhorn was the active executable. If that happened,
    # einhorn might not know about a dead child, so let's check
    # them all
    dead = []
    updated_state[:children].each do |pid, v|
      begin
        pid = Process.wait(pid, Process::WNOHANG)
        dead << pid if pid
      rescue Errno::ECHILD
        dead << pid
      end
    end
    Einhorn::Event::Timer.open(0) do
      dead.each {|pid| Einhorn::Command.cleanup(pid)}
    end
  end

  default = store.default_state
  added_keys = default.keys - updated_state.keys
  deleted_keys = updated_state.keys - default.keys
  return [updated_state, message.first] if added_keys.length == 0 && deleted_keys.length == 0

  added_keys.each {|key| updated_state[key] = default[key]}
  deleted_keys.each {|key| updated_state.delete(key)}

  message << "adding default values for #{added_keys.inspect}"
  message << "deleting values for #{deleted_keys.inspect}"
  message = "State format for #{store_name} has changed: #{message.join(', ')}"

  # Can't print yet, since state hasn't been set, so we pass along the message.
  [updated_state, message]
end

.upgrade_commandline(einhorn_flags = []) ⇒ Object

Construct and a command and args that can be used to re-exec Einhorn for upgrades.



358
359
360
361
362
363
364
365
366
367
368
369
 
# File 'lib/einhorn.rb', line 358

def self.upgrade_commandline(einhorn_flags=[])
  cmdline = []
  if Einhorn::State.reexec_commandline
    cmdline += Einhorn::State.reexec_commandline
  else
    cmdline << Einhorn::TransientState.script_name
  end
  cmdline += einhorn_flags
  cmdline << '--'
  cmdline += Einhorn::State.cmd
  [cmdline[0], cmdline[1..-1]]
end

.which(cmd) ⇒ Object 



207
208
209
210
211
212
213
214
215
216
217
218
 
# File 'lib/einhorn.rb', line 207

def self.which(cmd)
  if cmd.include?('/')
    return cmd if File.exists?(cmd)
    raise "Could not find #{cmd}"
  else
    ENV['PATH'].split(':').each do |f|
      abs = File.join(f, cmd)
      return abs if File.exists?(abs)
    end
    raise "Could not find #{cmd} in PATH"
  end
end

.worker_ps_name ⇒ Object 



306
307
308
 
# File 'lib/einhorn.rb', line 306

def self.worker_ps_name
  Einhorn::State.cmd_name ? "ruby #{Einhorn::State.cmd_name}" : Einhorn::State.orig_cmd.join(' ')
end