vm_method.c: add new ruby::method-cache-clear dtrace probe

* vm_method.c (rb_clear_method_cache_by_class): fire
  ruby::method-cache-clear probe on global or klass-level method cache
  clear [Bug #9190]
* probes.d (provider ruby): new dtrace probe
* doc/dtrace_probes.rdoc: docs for new probe
* test/dtrace/test_method_cache.rb: test for new probe

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44103 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,12 @@
+Tue Dec 10 07:48:29 2013  Aman Gupta <ruby@tmm1.net>
+
+	* vm_method.c (rb_clear_method_cache_by_class): fire
+	  ruby::method-cache-clear probe on global or klass-level method cache
+	  clear [Bug #9190]
+	* probes.d (provider ruby): new dtrace probe
+	* doc/dtrace_probes.rdoc: docs for new probe
+	* test/dtrace/test_method_cache.rb: test for new probe
+
 Tue Dec 10 06:14:11 2013  Eric Hodel  <drbrain@segment7.net>
 
 	* ext/.document:  Remove curses from documentable directories.

doc/dtrace_probes.rdoc

@@ -169,4 +169,10 @@ with when they are fired and the arguments they take:
 [ruby:::gc-sweep-end();]
   Fired at the end of a sweep phase.
 
+[ruby:::method-cache-clear(class, sourcefile, lineno);]
+  Fired when the method cache is cleared.
+
+    class is the classname being cleared, or "global" (string)
+    sourcefile the file being parsed (string)
+    lineno the line number where the source ended (int)
 

probes.d

@@ -214,6 +214,17 @@ provider ruby {
      Fired at the end of a sweep phase.
   */
   probe gc__sweep__end();
+
+  /*
+     ruby:::method-cache-clear(class, filename, lineno);
+
+     This probe is fired when the method cache is cleared.
+
+     * `class` the name of the class or "global" (a string)
+     * `filename` the file name where the cache is _being cleared_ (a string)
+     * `lineno` the line number where the cache is _being cleared_ (an int)
+  */
+  probe method__cache__clear(const char *class, const char *filename, int lineno);
 };
 
 #pragma D attributes Stable/Evolving/Common provider ruby provider

test/dtrace/test_method_cache.rb

@@ -0,0 +1,28 @@
+require_relative 'helper'
+
+module DTrace
+  class TestMethodCacheClear < TestCase
+    def test_method_cache_clear
+      trap_probe(probe, <<-code) do |_,rbfile,lines|
+        class String; end
+        class String; def abc() end end
+        class Object; def abc() end end
+      code
+        assert_not_includes lines, "String #{rbfile} 1\n"
+        assert_includes     lines, "String #{rbfile} 2\n"
+        assert_includes     lines, "global #{rbfile} 3\n"
+      end
+    end
+
+    private
+    def probe
+      <<-eoprobe
+ruby$target:::method-cache-clear
+/arg1/
+{
+  printf("%s %s %d\\n", copyinstr(arg0), copyinstr(arg1), arg2);
+}
+      eoprobe
+    end
+  end
+end if defined?(DTrace::TestCase)

vm_method.c

@@ -61,7 +61,13 @@ void
 rb_clear_method_cache_by_class(VALUE klass)
 {
     if (klass && klass != Qundef) {
-	if (klass == rb_cBasicObject || klass == rb_cObject || klass == rb_mKernel) {
+	int global = klass == rb_cBasicObject || klass == rb_cObject || klass == rb_mKernel;
+
+	if (RUBY_DTRACE_METHOD_CACHE_CLEAR_ENABLED()) {
+	    RUBY_DTRACE_METHOD_CACHE_CLEAR(global ? "global" : rb_class2name(klass), rb_sourcefile(), rb_sourceline());
+	}
+
+	if (global) {
 	    INC_GLOBAL_METHOD_STATE();
 	}
 	else {