Trap WINCH to QUIT children without respawning

This will only be enabled if we're daemonized and "real" WINCH
signals cannot be generated by resizing the terminal.  This is
to avoid confusing developers who run in the foreground of a
terminal.

Additionally document procedures for reexecuting a running
binary.

1 files changed, 15 insertions, 2 deletions

diff --git a/lib/unicorn.rb b/lib/unicorn.rb
index 7b7c4bb..9245f53 100644
--- a/lib/unicorn.rb
+++ b/lib/unicorn.rb
@@ -161,6 +161,7 @@ module Unicorn
       @rd_sig, @wr_sig = IO.pipe unless (@rd_sig && @wr_sig)
       @rd_sig.nonblock = @wr_sig.nonblock = true
       ready = mode = nil
+      respawn = true
 
       QUEUE_SIGS.each { |sig| trap_deferred(sig) }
       trap('CHLD') { |sig_nr| awaken_master }
@@ -172,7 +173,7 @@ module Unicorn
           case (mode = @sig_queue.shift)
           when nil
             murder_lazy_workers
-            spawn_missing_workers
+            spawn_missing_workers if respawn
           when 'QUIT' # graceful shutdown
             break
           when 'TERM', 'INT' # immediate shutdown
@@ -183,7 +184,16 @@ module Unicorn
             Unicorn::Util.reopen_logs
           when 'USR2' # exec binary, stay alive in case something went wrong
             reexec
+          when 'WINCH'
+            if ppid == 1 || getpgrp != $$
+              respawn = false
+              logger.info "gracefully stopping all workers"
+              kill_each_worker('QUIT')
+            else
+              logger.info "SIGWINCH ignored because we're not daemonized"
+            end
           when 'HUP'
+            respawn = true
             if @config.config_file
               load_config!
               redo # immediate reaping since we may have QUIT workers
@@ -239,7 +249,8 @@ module Unicorn
     private
 
     # list of signals we care about and trap in master.
-    QUEUE_SIGS = %w(QUIT INT TERM USR1 USR2 HUP).map { |x| x.freeze }.freeze
+    QUEUE_SIGS =
+      %w(WINCH QUIT INT TERM USR1 USR2 HUP).map { |x| x.freeze }.freeze
 
     # defer a signal for later processing in #join (master process)
     def trap_deferred(signal)
@@ -271,6 +282,7 @@ module Unicorn
             logger.error "reaped exec()-ed PID:#{pid} status=#{$?.exitstatus}"
             @reexec_pid = 0
             self.pid = @pid.chomp('.oldbin') if @pid
+            $0 = "unicorn master"
           else
             worker = @workers.delete(pid)
             worker.tempfile.close rescue nil
@@ -324,6 +336,7 @@ module Unicorn
         @before_exec.call(self) if @before_exec
         exec(*cmd)
       end
+      $0 = "unicorn master (old)"
     end
 
     # forcibly terminate all workers that haven't checked in in @timeout