From f385ed423e11ad40822f688bc592eaa78efa5b34 Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Mon, 9 Jan 2017 18:59:00 +0000
Subject: eventmachine: wait for deferred actions to finish

Since EventMachine 1.0.0 in 2012, the EM.defers_finish? API
exists to check for the existence of deferred actions.
Support it if it exists in the running version of EM and
update the note in our SIGNALS document.

Thanks to <alex0375@gmail.com> on the mailing list for bringing
this up:
https://bogomips.org/rainbows-public/CAKwvcL-VH3we4qA1pkNAstTmWvqNA=Rir2N_YiWztV_qbaLQvA@mail.gmail.com/
---
 SIGNALS                       |  6 +++---
 lib/rainbows/event_machine.rb | 10 +++++++++-
 t/app_deferred.ru             |  8 +++++++-
 t/t0700-app-deferred.sh       | 18 +++++++++++++++---
 4 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/SIGNALS b/SIGNALS
index e53c3e4..fa95a1c 100644
--- a/SIGNALS
+++ b/SIGNALS
@@ -24,9 +24,9 @@ between \Rainbows!, unicorn and nginx.
 * INT/TERM - quick shutdown, kills all workers immediately
 
 * QUIT - graceful shutdown, waits for workers to finish their
-  current request before finishing.  This currently does not
-  wait for requests deferred to a separate thread when using
-  EventMachine (when app.deferred?(env) => true)
+  current request before finishing.  Since Rainbows 5.1.0 (Jan 2017),
+  this waits requests deferred to a separate thread with
+  EventMachine (app.deferred?(env) => true).
 
 * USR1 - reopen all logs owned by the master and all workers
   See Unicorn::Util.reopen_logs for what is considered a log.
diff --git a/lib/rainbows/event_machine.rb b/lib/rainbows/event_machine.rb
index b326e26..896fdac 100644
--- a/lib/rainbows/event_machine.rb
+++ b/lib/rainbows/event_machine.rb
@@ -65,6 +65,11 @@ module Rainbows::EventMachine
     end
   end
 
+  def defers_finished?
+    # EventMachine 1.0.0+ has defers_finished?
+    EM.respond_to?(:defers_finished?) ? EM.defers_finished? : true
+  end
+
   # runs inside each forked worker, this sits around and waits
   # for connections and doesn't die until the parent dies (or is
   # given a INT, QUIT, or TERM signal)
@@ -101,7 +106,10 @@ module Rainbows::EventMachine
         end
       end
       EM.add_periodic_timer(1) do
-        EM.stop if ! Rainbows.tick && conns.empty? && EM.reactor_running?
+        if ! Rainbows.tick && conns.empty? && defers_finished? &&
+            EM.reactor_running?
+          EM.stop
+        end
       end
       LISTENERS.map! do |s|
         EM.watch(s, Rainbows::EventMachine::Server) do |c|
diff --git a/t/app_deferred.ru b/t/app_deferred.ru
index a70b33b..b3d7ff1 100644
--- a/t/app_deferred.ru
+++ b/t/app_deferred.ru
@@ -6,12 +6,18 @@
 
 class DeferredApp < Struct.new(:app)
   def deferred?(env)
-    env["PATH_INFO"] == "/deferred"
+    env["PATH_INFO"] =~ %r{\A/deferred}
   end
 
   def call(env)
     env["rack.multithread"] or raise RuntimeError, "rack.multithread not true"
     body = "#{Thread.current.inspect}\n"
+    if env["PATH_INFO"] =~ %r{\A/deferred(\d+)}
+      delay = $1.to_i
+      File.open(ENV['fifo'], 'w') { |fp| fp.write "sleeping #{delay}s\n" }
+      body = "deferred sleep\n"
+      sleep(delay)
+    end
     headers = {
       "Content-Type" => "text/plain",
       "Content-Length" => body.size.to_s,
diff --git a/t/t0700-app-deferred.sh b/t/t0700-app-deferred.sh
index 90614b2..188fdde 100755
--- a/t/t0700-app-deferred.sh
+++ b/t/t0700-app-deferred.sh
@@ -15,7 +15,7 @@ CONFIG_RU=app_deferred.ru
 t_begin "setup and start" && {
 	rainbows_setup
 	rtmpfiles deferred_err deferred_out sync_err sync_out
-	rainbows -D -c $unicorn_config $CONFIG_RU
+	fifo=$fifo rainbows -D -c $unicorn_config $CONFIG_RU
 	rainbows_wait_start
 }
 
@@ -36,8 +36,20 @@ t_begin "deferred requests run in a different thread" && {
 	test x"$(uniq < $deferred_out)" != x"$sync_thread"
 }
 
-t_begin "termination signal sent" && {
-	kill $rainbows_pid
+t_begin "deferred requests run after graceful shutdown" && {
+	# XXX sleeping 5s ought to be enough for SIGQUIT to arrive,
+	# hard to tell with overloaded systems...
+	s=5
+	curl -sSf --no-buffer http://$listen/deferred$s \
+		>$deferred_out 2>$deferred_err &
+	curl_pid=$!
+	msg="$(cat $fifo)"
+	kill -QUIT $rainbows_pid
+	test x"$msg" = x"sleeping ${s}s"
+	wait $curl_pid # for curl to finish
+	test $? -eq 0
+	test ! -s $deferred_err
+	test x"$(cat $deferred_out)" = 'xdeferred sleep'
 }
 
 t_begin "no errors in stderr" && check_stderr
-- 
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