forked from ddollar/foreman
-
Notifications
You must be signed in to change notification settings - Fork 0
/
engine.rb
494 lines (427 loc) · 12 KB
/
engine.rb
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
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
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
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
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
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
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
require "foreman"
require "foreman/env"
require "foreman/process"
require "foreman/procfile"
require "tempfile"
require "fileutils"
require "thread"
class Foreman::Engine
# The signals that the engine cares about.
#
HANDLED_SIGNALS = [ :TERM, :INT, :HUP, :USR1, :USR2 ]
attr_reader :env
attr_reader :options
attr_reader :processes
# Create an +Engine+ for running processes
#
# @param [Hash] options
#
# @option options [String] :formation (all=1) The process formation to use
# @option options [Fixnum] :port (5000) The base port to assign to processes
# @option options [String] :root (Dir.pwd) The root directory from which to run processes
#
def initialize(options={})
@options = options.dup
@options[:formation] ||= "all=1"
@options[:timeout] ||= 5
@env = {}
@mutex = Mutex.new
@names = {}
@processes = []
@running = {}
@readers = {}
@shutdown = false
# Self-pipe for deferred signal-handling (ala djb: http://cr.yp.to/docs/selfpipe.html)
reader, writer = create_pipe
reader.close_on_exec = true if reader.respond_to?(:close_on_exec)
writer.close_on_exec = true if writer.respond_to?(:close_on_exec)
@selfpipe = { :reader => reader, :writer => writer }
# Set up a global signal queue
# http://blog.rubybestpractices.com/posts/ewong/016-Implementing-Signal-Handlers.html
Thread.main[:signal_queue] = []
end
# Start the processes registered to this +Engine+
#
def start
register_signal_handlers
startup
spawn_processes
watch_for_output
sleep 0.1
wait_for_shutdown_or_child_termination
shutdown
exit(@exitstatus) if @exitstatus
end
# Set up deferred signal handlers
#
def register_signal_handlers
HANDLED_SIGNALS.each do |sig|
if ::Signal.list.include? sig.to_s
trap(sig) { Thread.main[:signal_queue] << sig ; notice_signal }
end
end
end
# Unregister deferred signal handlers
#
def restore_default_signal_handlers
HANDLED_SIGNALS.each do |sig|
trap(sig, :DEFAULT) if ::Signal.list.include? sig.to_s
end
end
# Wake the main thread up via the selfpipe when there's a signal
#
def notice_signal
@selfpipe[:writer].write_nonblock( '.' )
rescue Errno::EAGAIN
# Ignore writes that would block
rescue Errno::EINTR
# Retry if another signal arrived while writing
retry
end
# Invoke the real handler for signal +sig+. This shouldn't be called directly
# by signal handlers, as it might invoke code which isn't re-entrant.
#
# @param [Symbol] sig the name of the signal to be handled
#
def handle_signal(sig)
case sig
when :TERM
handle_term_signal
when :INT
handle_interrupt
when :HUP
handle_hangup
when *HANDLED_SIGNALS
handle_signal_forward(sig)
else
system "unhandled signal #{sig}"
end
end
# Handle a TERM signal
#
def handle_term_signal
system "SIGTERM received, starting shutdown"
@shutdown = true
end
# Handle an INT signal
#
def handle_interrupt
system "SIGINT received, starting shutdown"
@shutdown = true
end
# Handle a HUP signal
#
def handle_hangup
system "SIGHUP received, starting shutdown"
@shutdown = true
end
def handle_signal_forward(signal)
system "#{signal} received, forwarding it to children"
kill_children signal
end
# Register a process to be run by this +Engine+
#
# @param [String] name A name for this process
# @param [String] command The command to run
# @param [Hash] options
#
# @option options [Hash] :env A custom environment for this process
#
def register(name, command, options={})
options[:env] ||= env
options[:cwd] ||= File.dirname(command.split(" ").first)
process = Foreman::Process.new(command, options)
@names[process] = name
@processes << process
end
# Clear the processes registered to this +Engine+
#
def clear
@names = {}
@processes = []
end
# Register processes by reading a Procfile
#
# @param [String] filename A Procfile from which to read processes to register
#
def load_procfile(filename)
options[:root] ||= File.dirname(filename)
Foreman::Procfile.new(filename).entries do |name, command|
register name, command, :cwd => options[:root]
end
self
end
# Load a .env file into the +env+ for this +Engine+
#
# @param [String] filename A .env file to load into the environment
#
def load_env(filename)
Foreman::Env.new(filename).entries do |name, value|
@env[name] = value
end
end
# Send a signal to all processes started by this +Engine+
#
# @param [String] signal The signal to send to each process
#
def kill_children(signal="SIGTERM")
if Foreman.windows?
@running.each do |pid, (process, index)|
system "sending #{signal} to #{name_for(pid)} at pid #{pid}"
begin
Process.kill("-#{signal}", pid)
rescue Errno::ESRCH, Errno::EPERM
end
end
else
begin
pids = @running.keys.compact
Process.kill("-#{signal}", *pids) unless pids.empty?
rescue Errno::ESRCH, Errno::EPERM
end
end
end
# Send a signal to the whole process group.
#
# @param [String] signal The signal to send
#
def killall(signal="SIGTERM")
if Foreman.windows?
kill_children(signal)
else
begin
Process.kill "-#{signal}", Process.pid
rescue Errno::ESRCH, Errno::EPERM
end
end
end
# Get the process formation
#
# @returns [Fixnum] The formation count for the specified process
#
def formation
@formation ||= parse_formation(options[:formation])
end
# List the available process names
#
# @returns [Array] A list of process names
#
def process_names
@processes.map { |p| @names[p] }
end
# Get the +Process+ for a specifid name
#
# @param [String] name The process name
#
# @returns [Foreman::Process] The +Process+ for the specified name
#
def process(name)
@names.invert[name]
end
# Yield each +Process+ in order
#
def each_process
process_names.each do |name|
yield name, process(name)
end
end
# Get the root directory for this +Engine+
#
# @returns [String] The root directory
#
def root
File.expand_path(options[:root] || Dir.pwd)
end
# Get the port for a given process and offset
#
# @param [Foreman::Process] process A +Process+ associated with this engine
# @param [Fixnum] instance The instance of the process
#
# @returns [Fixnum] port The port to use for this instance of this process
#
def port_for(process, instance, base=nil)
if base
base + (@processes.index(process.process) * 100) + (instance - 1)
else
base_port + (@processes.index(process) * 100) + (instance - 1)
end
end
# Get the base port for this foreman instance
#
# @returns [Fixnum] port The base port
#
def base_port
(options[:port] || env["PORT"] || ENV["PORT"] || 5000).to_i
end
# deprecated
def environment
env
end
private
### Engine API ######################################################
def startup
raise TypeError, "must use a subclass of Foreman::Engine"
end
def output(name, data)
raise TypeError, "must use a subclass of Foreman::Engine"
end
def shutdown
raise TypeError, "must use a subclass of Foreman::Engine"
end
## Helpers ##########################################################
def create_pipe
IO.method(:pipe).arity.zero? ? IO.pipe : IO.pipe("BINARY")
end
def name_for(pid)
process, index = @running[pid]
name_for_index(process, index)
end
def name_for_index(process, index)
[ @names[process], index.to_s ].compact.join(".")
end
def parse_formation(formation)
pairs = formation.to_s.gsub(/\s/, "").split(",")
pairs.inject(Hash.new(0)) do |ax, pair|
process, amount = pair.split("=")
process == "all" ? ax.default = amount.to_i : ax[process] = amount.to_i
ax
end
end
def output_with_mutex(name, message)
@mutex.synchronize do
output name, message
end
end
def system(message)
output_with_mutex "system", message
end
def termination_message_for(status)
if status.exited?
"exited with code #{status.exitstatus}"
elsif status.signaled?
"terminated by SIG#{Signal.list.invert[status.termsig]}"
else
"died a mysterious death"
end
end
def flush_reader(reader)
until reader.eof?
data = reader.gets
output_with_mutex name_for(@readers.key(reader)), data
end
end
## Engine ###########################################################
def spawn_processes
@processes.each do |process|
1.upto(formation[@names[process]]) do |n|
reader, writer = create_pipe
begin
pid = process.run(:output => writer, :env => {
"PORT" => port_for(process, n).to_s,
"PS" => name_for_index(process, n)
})
writer.puts "started with pid #{pid}"
rescue Errno::ENOENT
writer.puts "unknown command: #{process.command}"
end
@running[pid] = [process, n]
@readers[pid] = reader
end
end
end
def read_self_pipe
@selfpipe[:reader].read_nonblock(11)
rescue Errno::EAGAIN, Errno::EINTR, Errno::EBADF, Errno::EWOULDBLOCK
# ignore
end
def handle_signals
while sig = Thread.main[:signal_queue].shift
self.handle_signal(sig)
end
end
def handle_io(readers)
readers.each do |reader|
next if reader == @selfpipe[:reader]
if reader.eof?
@readers.delete_if { |key, value| value == reader }
else
data = reader.gets
output_with_mutex name_for(@readers.invert[reader]), data
end
end
end
def watch_for_output
Thread.new do
begin
loop do
io = IO.select([@selfpipe[:reader]] + @readers.values, nil, nil, 30)
read_self_pipe
handle_signals
handle_io(io ? io.first : [])
end
rescue Exception => ex
puts ex.message
puts ex.backtrace
end
end
end
def wait_for_shutdown_or_child_termination
loop do
# Stop if it is time to shut down (asked via a signal)
break if @shutdown
# Stop if any of the children died
break if check_for_termination
# Sleep for a moment and do not blow up if any signals are coming our way
begin
sleep(1)
rescue Exception
# noop
end
end
# Ok, we have exited from the main loop, time to shut down gracefully
terminate_gracefully
end
def check_for_termination
# Check if any of the children have died off
pid, status = begin
Process.wait2(-1, Process::WNOHANG)
rescue Errno::ECHILD
return nil
end
# record the exit status
@exitstatus ||= status.exitstatus if status
# If no childred have died, nothing to do here
return nil unless pid
# Log the information about the process that exited
output_with_mutex name_for(pid), termination_message_for(status)
# Delete it from the list of running processes and return its pid
@running.delete(pid)
return pid
end
def terminate_gracefully
restore_default_signal_handlers
# Tell all children to stop gracefully
if Foreman.windows?
system "sending SIGKILL to all processes"
kill_children "SIGKILL"
else
system "sending SIGTERM to all processes"
kill_children "SIGTERM"
end
# Wait for all children to stop or until the time comes to kill them all
start_time = Time.now
while Time.now - start_time <= options[:timeout]
return if @running.empty?
check_for_termination
# Sleep for a moment and do not blow up if more signals are coming our way
begin
sleep(0.1)
rescue Exception
# noop
end
end
# Ok, we have no other option than to kill all of our children
system "sending SIGKILL to all processes"
kill_children "SIGKILL"
end
end