Merge branch 'ready_pipe'

* ready_pipe:
  launcher: no point in sync-ing $stdin
  launcher: fix compatibility with other servers
  clarify errors when listeners fail to bind
  launcher: descriptive error message on startup failure
  Avoid leaking ready pipe file descriptor to workers
  exit with failure if master dies when daemonized

1 files changed, 32 insertions, 6 deletions

diff --git a/lib/unicorn/launcher.rb b/lib/unicorn/launcher.rb
index 1229b84..e71f93b 100644
--- a/lib/unicorn/launcher.rb
+++ b/lib/unicorn/launcher.rb
@@ -1,6 +1,6 @@
 # -*- encoding: binary -*-
 
-$stdin.sync = $stdout.sync = $stderr.sync = true
+$stdout.sync = $stderr.sync = true
 $stdin.binmode
 $stdout.binmode
 $stderr.binmode
@@ -19,21 +19,47 @@ class Unicorn::Launcher
   #     the directory it was started in when being re-executed
   #     to pickup code changes if the original deployment directory
   #     is a symlink or otherwise got replaced.
-  def self.daemonize!
+  def self.daemonize!(options = nil)
     $stdin.reopen("/dev/null")
 
     # We only start a new process group if we're not being reexecuted
     # and inheriting file descriptors from our parent
     unless ENV['UNICORN_FD']
-      exit if fork
-      Process.setsid
-      exit if fork
+      if options
+        # grandparent - reads pipe, exits when master is ready
+        #  \_ parent  - exits immediately ASAP
+        #      \_ unicorn master - writes to pipe when ready
 
+        rd, wr = IO.pipe
+        grandparent = $$
+        if fork
+          wr.close # grandparent does not write
+        else
+          rd.close # unicorn master does not read
+          Process.setsid
+          exit if fork # parent dies now
+        end
+
+        if grandparent == $$
+          # this will block until HttpServer#join runs (or it dies)
+          master_pid = (rd.readpartial(16) rescue nil).to_i
+          unless master_pid > 1
+            warn "master failed to start, check stderr log for details"
+            exit!(1)
+          end
+          exit 0
+        else # unicorn master process
+          options[:ready_pipe] = wr
+        end
+      else # backwards compat
+        exit if fork
+        Process.setsid
+        exit if fork
+      end
       # $stderr/$stderr can/will be redirected separately in the Unicorn config
       Unicorn::Configurator::DEFAULTS[:stderr_path] = "/dev/null"
       Unicorn::Configurator::DEFAULTS[:stdout_path] = "/dev/null"
     end
-    $stdin.sync = $stdout.sync = $stderr.sync = true
   end
 
 end