4 files changed, 44 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog
index a822ad0ebe..064fbe0e62 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Sun Jun 14 14:57:57 2009  Koichi Sasada  <ko1@atdot.net>
+
+	* thread.c, vm_eval.c: add Thread.backtrace. 
+
+	* test/ruby/test_thread.rb: add a test.
+
 Sun Jun 14 13:58:32 2009  Koichi Sasada  <ko1@atdot.net>
 
 	* transcode.c (transcode_restartable0): revert last commit because
diff --git a/test/ruby/test_thread.rb b/test/ruby/test_thread.rb
index b460cadea9..d0c35d8273 100644
--- a/test/ruby/test_thread.rb
+++ b/test/ruby/test_thread.rb
@@ -516,4 +516,14 @@ class TestThreadGroup < Test::Unit::TestCase
     c.class_eval { def initialize; end }
     assert_raise(ThreadError) { c.new.start }
   end
+
+  def test_backtrace
+    Thread.new{
+      assert_equal(Array, Thread.main.backtrace.class)
+    }.join
+
+    t = Thread.new{}
+    t.join
+    assert_equal(nil, t.backtrace)
+  end
 end
diff --git a/thread.c b/thread.c
index 573ace640c..efe5d02dd5 100644
--- a/thread.c
+++ b/thread.c
@@ -3817,6 +3817,14 @@ ruby_suppress_tracing(VALUE (*func)(VALUE, int), VALUE arg, int always)
     return result;
 }
 
+VALUE rb_thread_backtrace(VALUE thval);
+
+static VALUE
+rb_thread_backtrace_m(VALUE thval)
+{
+    return rb_thread_backtrace(thval);
+}
+
 /*
  *  +Thread+ encapsulates the behavior of a thread of
  *  execution, including the main thread of the Ruby script.
@@ -3873,6 +3881,7 @@ Init_Thread(void)
     rb_define_method(rb_cThread, "abort_on_exception=", rb_thread_abort_exc_set, 1);
     rb_define_method(rb_cThread, "safe_level", rb_thread_safe_level, 0);
     rb_define_method(rb_cThread, "group", rb_thread_group, 0);
+    rb_define_method(rb_cThread, "backtrace", rb_thread_backtrace_m, 0);
 
     rb_define_method(rb_cThread, "inspect", rb_thread_inspect, 0);
 
diff --git a/vm_eval.c b/vm_eval.c
index 596701e2c0..2dff373e42 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1348,6 +1348,25 @@ rb_make_backtrace(void)
 }
 
 VALUE
+rb_thread_backtrace(VALUE thval)
+{
+    rb_thread_t *th;
+    GetThreadPtr(thval, th);
+
+    switch (th->status) {
+      case THREAD_RUNNABLE:
+      case THREAD_STOPPED:
+      case THREAD_STOPPED_FOREVER:
+	break;
+      case THREAD_TO_KILL:
+      case THREAD_KILLED:
+	return Qnil;
+    }
+
+    return vm_backtrace(th, 0);
+}
+
+VALUE
 rb_backtrace_each(rb_backtrace_iter_func *iter, void *arg)
 {
     return vm_backtrace_each(GET_THREAD(), -1, iter, arg);