server.rb in tork-19.5.0

- old
+ new

@@ -1,66 +1,71 @@
 require 'socket'
 require 'json'
 require 'shellwords'
 require 'set'
+require 'tork/bridge'
 
 module Tork
 class Server
 
   def self.address program=$0
     ".#{program}.sock"
   end
 
   def initialize
+    begin
+      @welcome = UNIXServer.open(address = Server.address)
+      # UNIX domain socket files are not automatically deleted on close
+      at_exit { File.delete address if File.socket? address }
+    rescue Errno::EADDRINUSE
+      # another instance of this program is already running in the same
+      # directory so become a remote control for it rather than exiting
+      warn "#{$0}: remotely controlling existing instance..."
+      exec 'tork-remote', $0
+    end
+
     # only JSON messages are supposed to be emitted on STDOUT
     # so make puts() in the user code write to STDERR instead
     @stdout = STDOUT.dup
     STDOUT.reopen STDERR
 
-    @clients = Set.new.add(STDIN)
-    @servers = Set.new
-    @address = Server.address
+    @servers = Set.new.add(@welcome)
+    @clients = Set.new; join STDIN # parent process connected on STDIN
   end
 
   def loop
-    begin
-      server = UNIXServer.open(@address)
-    rescue SystemCallError => error
-      warn "#{$0}: #{error}; retrying in #{timeout = 1 + rand(10)} seconds..."
-      sleep timeout
-      retry
-    end
-
     catch :quit do
-      @servers.add server
       while @clients.include? STDIN
         IO.select((@servers + @clients).to_a).first.each do |stream|
-          @client = stream
+          if stream == @welcome
+            join stream.accept
 
-          if stream == server
-            @clients.add stream.accept
-
           elsif (stream.eof? rescue true)
-            @clients.delete stream
+            part stream
 
-          elsif @command = hear(stream, stream.gets)
+          elsif @command = hear(stream, stream.gets) and not @command.empty?
             recv stream, @command
           end
         end
       end
     end
-  ensure
-    # UNIX domain socket files are not deleted automatically upon closing
-    File.delete @address if File.socket? @address
   end
 
   def quit
     throw :quit
   end
 
 protected
 
+  def join client
+    @clients.add client
+  end
+
+  def part client
+    @clients.delete client
+  end
+
   # Returns nil if the message received was not meant for processing.
   def hear sender, message
     JSON.load message
   rescue JSON::ParserError => error
     if @clients.include? sender
@@ -71,11 +76,13 @@
       tell @clients, message, false
       nil
     end
   end
 
+  # Sets the @client variable to the client we are currently serving.
   def recv client, command
+    @client = client
     __send__(*command)
   rescue => error
     tell client, error
   end
 
@@ -91,11 +98,11 @@
     if prefix
       message = Array(message).join("\n").gsub(/^/, "#{$0}: ")
     end
 
     targets =
-      if one_or_more_clients.kind_of? IO
+      if one_or_more_clients.respond_to? :to_io
         [one_or_more_clients]
       else
         Array(one_or_more_clients)
       end
 
@@ -111,29 +118,16 @@
       end
     end
   end
 
   def popen command
-    child = IO.popen(command, 'r+')
+    child = Bridge.new(command)
     @servers.add child
     child
   end
 
   def pclose child
-    return unless @servers.delete? child
-
-    # this should be enough to stop programs that use Tork::Server#loop
-    # because their IO.select() loop terminates on the closing of STDIN
-    child.close_write
-
-    # but some programs like tork-herald(1) need to be killed explicitly
-    # because they do not follow our convention of exiting on STDIN close
-    Process.kill :SIGTERM, child.pid
-    Process.waitpid child.pid
-
-    # this will block until the child process has exited so we must kill it
-    # explicitly (as above) to ensure that this program does not hang here
-    child.close_read
+    child.disconnect if @servers.delete? child
   end
 
 end
 end