Add Process.setproctitle().

* ruby.c (Process.setproctitle): New method to change the title of
  the running process that is shown in ps(1). [Feature #8696]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42425 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Aug  7 23:05:55 2013  Akinori MUSHA  <knu@iDaemons.org>
+
+	* ruby.c (Process.setproctitle): New method to change the title of
+	  the running process that is shown in ps(1). [Feature #8696]
+
 Wed Aug  7 20:05:38 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (rb_big_odd_p): Check the bignum length.

NEWS

@@ -48,6 +48,10 @@ with all sufficient information, see the ChangeLog file.
   * misc
     * Mutex#owned? is no longer experimental.
 
+* Process
+  * New methods:
+    * Process.setproctitle() sets the process title without affecting $0.
+
 * String
   * New methods:
     * String#scrub and String#scrub! verify and fix invalid byte sequence.

ruby.c

@@ -1780,21 +1780,49 @@ rb_load_file_str(VALUE fname_v)
     return load_file(rb_parser_new(), fname_v, 0, cmdline_options_init(&opt));
 }
 
+/*
+ *  call-seq:
+ *     Process.argv0  -> frozen_string
+ *
+ *  Returns the name of the script being executed.  The value is not
+ *  affected by assigning a new value to $0.
+ */
+
+static VALUE
+proc_argv0(VALUE process)
+{
+    return rb_orig_progname;
+}
+
+/*
+ *  call-seq:
+ *     Process.setproctitle(string)  -> string
+ *
+ *  Returns the process title that appears on the ps(1) command.  Not
+ *  necessarily effective on all platforms.
+ *
+ *  Calling this method does not affect the value of $0.
+ *
+ *     Process.setproctitle('myapp: worker #%d' % worker_id)
+ */
+
+static VALUE
+proc_setproctitle(VALUE process, VALUE title)
+{
+    StringValue(title);
+
+    setproctitle("%.*s", RSTRING_LENINT(title), RSTRING_PTR(title));
+
+    return title;
+}
+
 static void
 set_arg0(VALUE val, ID id)
 {
-    char *s;
-    long i;
-
     if (origarg.argv == 0)
 	rb_raise(rb_eRuntimeError, "$0 not initialized");
-    StringValue(val);
-    s = RSTRING_PTR(val);
-    i = RSTRING_LEN(val);
 
-    setproctitle("%.*s", (int)i, s);
-
-    rb_progname = rb_obj_freeze(rb_external_str_new(s, i));
+    rb_progname = rb_str_new_frozen(proc_setproctitle(rb_mProcess, val));
 }
 
 /*! Sets the current script name to this value.
@@ -1886,6 +1914,8 @@ ruby_prog_init(void)
     rb_define_hooked_variable("$0", &rb_progname, 0, set_arg0);
     rb_define_hooked_variable("$PROGRAM_NAME", &rb_progname, 0, set_arg0);
 
+    rb_define_module_function(rb_mProcess, "setproctitle", proc_setproctitle, 1);
+
     /*
      * ARGV contains the command line arguments used to run ruby with the
      * first value containing the name of the executable.

test/ruby/test_rubyoptions.rb

@@ -477,6 +477,25 @@ class TestRubyOptions < Test::Unit::TestCase
     end
   end
 
+  def test_setproctitle
+    skip "platform dependent feature" if /linux|freebsd|netbsd|openbsd|darwin/ !~ RUBY_PLATFORM
+
+    with_tmpchdir do
+      write_file("test-script", "$_0 = $0.dup; Process.setproctitle('hello world'); $0 == $_0 or Process.setproctitle('$0 changed!'); sleep 60")
+
+      pid = spawn(EnvUtil.rubybin, "test-script")
+      ps = nil
+      10.times do
+        sleep 0.1
+        ps = `ps -p #{pid} -o command`
+        break if /hello world/ =~ ps
+      end
+      assert_match(/hello world/, ps)
+      Process.kill :KILL, pid
+      Process.wait(pid)
+    end
+  end
+
   module SEGVTest
     opts = {}
     if /mswin|mingw/ =~ RUBY_PLATFORM