make monitor.so for performance. (#2576)

Recent monitor.rb has performance problem because of interrupt
handlers. 'Monitor#synchronize' is frequently used primitive
so the performance of this method is important.

This patch rewrite 'monitor.rb' with 'monitor.so' (C-extension)
and make it faster. See [Feature #16255] for details.

Monitor class objects are normal object which include MonitorMixin.
This patch introduce a Monitor class which is implemented on C
and MonitorMixin uses Monitor object as re-entrant (recursive)
Mutex. This technique improve performance because we don't need
to care atomicity and we don't need accesses to instance variables
any more on Monitor class.

NEWS

@@ -511,6 +511,9 @@ File::
   * File.realpath now uses realpath(3) on many platforms, which can
     significantly improve performance.
 
+Monitor::
+  * Monitor class is written in C-extension. [Feature #16255]
+
 Thread::
 
   * VM stack memory allocation is now combined with native thread stack,

ext/monitor/depend

@@ -0,0 +1,13 @@
+# AUTOGENERATED DEPENDENCIES START
+monitor.o: $(RUBY_EXTCONF_H)
+monitor.o: $(arch_hdrdir)/ruby/config.h
+monitor.o: $(hdrdir)/ruby/assert.h
+monitor.o: $(hdrdir)/ruby/backward.h
+monitor.o: $(hdrdir)/ruby/defines.h
+monitor.o: $(hdrdir)/ruby/intern.h
+monitor.o: $(hdrdir)/ruby/missing.h
+monitor.o: $(hdrdir)/ruby/ruby.h
+monitor.o: $(hdrdir)/ruby/st.h
+monitor.o: $(hdrdir)/ruby/subst.h
+monitor.o: monitor.c
+# AUTOGENERATED DEPENDENCIES END

ext/monitor/extconf.rb

@@ -0,0 +1,2 @@
+require 'mkmf'
+create_makefile('monitor')

ext/monitor/lib/monitor.rb

@@ -86,10 +86,10 @@
 # This Class is implemented as subclass of Array which includes the
 # MonitorMixin module.
 #
-module MonitorMixin
-  EXCEPTION_NEVER = {Exception => :never}.freeze
-  EXCEPTION_IMMEDIATE = {Exception => :immediate}.freeze
 
+require 'monitor.so'
+
+module MonitorMixin
   #
   # FIXME: This isn't documented in Nutshell.
   #
@@ -97,8 +97,6 @@ module MonitorMixin
   # above calls while_wait and signal, this class should be documented.
   #
   class ConditionVariable
-    class Timeout < Exception; end
-
     #
     # Releases the lock held in the associated monitor and waits; reacquires the lock on wakeup.
     #
@@ -106,17 +104,13 @@ module MonitorMixin
     # even if no other thread doesn't signal.
     #
     def wait(timeout = nil)
-      Thread.handle_interrupt(EXCEPTION_NEVER) do
-        @monitor.__send__(:mon_check_owner)
-        count = @monitor.__send__(:mon_exit_for_cond)
-        begin
-          Thread.handle_interrupt(EXCEPTION_IMMEDIATE) do
-            @cond.wait(@monitor.instance_variable_get(:@mon_mutex), timeout)
-          end
-          return true
-        ensure
-          @monitor.__send__(:mon_enter_for_cond, count)
-        end
+      @monitor.mon_check_owner
+      count = @monitor.__send__(:exit_for_cond)
+      begin
+        @cond.wait(@monitor.__send__(:mutex_for_cond), timeout)
+        return true
+      ensure
+        @monitor.__send__(:enter_for_cond, count)
       end
     end
 
@@ -142,7 +136,7 @@ module MonitorMixin
     # Wakes up the first thread in line waiting for this lock.
     #
     def signal
-      @monitor.__send__(:mon_check_owner)
+      @monitor.mon_check_owner
       @cond.signal
     end
 
@@ -150,7 +144,7 @@ module MonitorMixin
     # Wakes up all threads waiting for this lock.
     #
     def broadcast
-      @monitor.__send__(:mon_check_owner)
+      @monitor.mon_check_owner
       @cond.broadcast
     end
 
@@ -171,15 +165,7 @@ module MonitorMixin
   # Attempts to enter exclusive section.  Returns +false+ if lock fails.
   #
   def mon_try_enter
-    if @mon_owner != Thread.current
-      unless @mon_mutex.try_lock
-        return false
-      end
-      @mon_owner = Thread.current
-      @mon_count = 0
-    end
-    @mon_count += 1
-    return true
+    @mon_data.try_enter
   end
   # For backward compatibility
   alias try_mon_enter mon_try_enter
@@ -188,12 +174,7 @@ module MonitorMixin
   # Enters exclusive section.
   #
   def mon_enter
-    if @mon_owner != Thread.current
-      @mon_mutex.lock
-      @mon_owner = Thread.current
-      @mon_count = 0
-    end
-    @mon_count += 1
+    @mon_data.enter
   end
 
   #
@@ -201,25 +182,21 @@ module MonitorMixin
   #
   def mon_exit
     mon_check_owner
-    @mon_count -=1
-    if @mon_count == 0
-      @mon_owner = nil
-      @mon_mutex.unlock
-    end
+    @mon_data.exit
   end
 
   #
   # Returns true if this monitor is locked by any thread
   #
   def mon_locked?
-    @mon_mutex.locked?
+    @mon_data.mon_locked?
   end
 
   #
   # Returns true if this monitor is locked by current thread.
   #
   def mon_owned?
-    @mon_mutex.locked? && @mon_owner == Thread.current
+    @mon_data.mon_owned?
   end
 
   #
@@ -227,14 +204,12 @@ module MonitorMixin
   # section automatically when the block exits.  See example under
   # +MonitorMixin+.
   #
-  def mon_synchronize
-    # Prevent interrupt on handling interrupts; for example timeout errors
-    # it may break locking state.
-    Thread.handle_interrupt(EXCEPTION_NEVER){ mon_enter }
+  def mon_synchronize(&b)
+    @mon_data.enter
     begin
       yield
     ensure
-      Thread.handle_interrupt(EXCEPTION_NEVER){ mon_exit }
+      @mon_data.exit
     end
   end
   alias synchronize mon_synchronize
@@ -244,7 +219,7 @@ module MonitorMixin
   # receiver.
   #
   def new_cond
-    return ConditionVariable.new(self)
+    return ConditionVariable.new(@mon_data)
   end
 
   private
@@ -260,31 +235,15 @@ module MonitorMixin
   # Initializes the MonitorMixin after being included in a class or when an
   # object has been extended with the MonitorMixin
   def mon_initialize
-    if defined?(@mon_mutex) && @mon_mutex_owner_object_id == object_id
+    if defined?(@mon_data) && @mon_data_owner_object_id == self.object_id
       raise ThreadError, "already initialized"
     end
-    @mon_mutex = Thread::Mutex.new
-    @mon_mutex_owner_object_id = object_id
-    @mon_owner = nil
-    @mon_count = 0
+    @mon_data = ::Monitor.new
+    @mon_data_owner_object_id = self.object_id
   end
 
   def mon_check_owner
-    if @mon_owner != Thread.current
-      raise ThreadError, "current thread not owner"
-    end
-  end
-
-  def mon_enter_for_cond(count)
-    @mon_owner = Thread.current
-    @mon_count = count
-  end
-
-  def mon_exit_for_cond
-    count = @mon_count
-    @mon_owner = nil
-    @mon_count = 0
-    return count
+    @mon_data.mon_check_owner
   end
 end
 
@@ -299,12 +258,17 @@ end
 #   end
 #
 class Monitor
-  include MonitorMixin
-  alias try_enter try_mon_enter
-  alias enter mon_enter
-  alias exit mon_exit
-end
+  def new_cond
+    ::MonitorMixin::ConditionVariable.new(self)
+  end
 
+  # for compatibility
+  alias try_mon_enter try_enter
+  alias mon_try_enter try_enter
+  alias mon_enter enter
+  alias mon_exit exit
+  alias mon_synchronize synchronize
+end
 
 # Documentation comments:
 #  - All documentation comes from Nutshell.

ext/monitor/monitor.c

@@ -0,0 +1,189 @@
+#include "ruby/ruby.h"
+
+/* Thread::Monitor */
+
+struct rb_monitor {
+    long count;
+    const VALUE owner;
+    const VALUE mutex;
+};
+
+static void
+monitor_mark(void *ptr)
+{
+    struct rb_monitor *mc = ptr;
+    rb_gc_mark(mc->owner);
+    rb_gc_mark(mc->mutex);
+}
+
+static size_t
+monitor_memsize(const void *ptr)
+{
+    return sizeof(struct rb_monitor);
+}
+
+static const rb_data_type_t monitor_data_type = {
+    "monitor",
+    {monitor_mark, RUBY_TYPED_DEFAULT_FREE, monitor_memsize,},
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY|RUBY_TYPED_WB_PROTECTED
+};
+
+static VALUE
+monitor_alloc(VALUE klass)
+{
+    struct rb_monitor *mc;
+    VALUE obj;
+
+    obj = TypedData_Make_Struct(klass, struct rb_monitor, &monitor_data_type, mc);
+    RB_OBJ_WRITE(obj, &mc->mutex, rb_mutex_new());
+    RB_OBJ_WRITE(obj, &mc->owner, Qnil);
+    mc->count = 0;
+
+    return obj;
+}
+
+static struct rb_monitor *
+monitor_ptr(VALUE monitor)
+{
+    struct rb_monitor *mc;
+    TypedData_Get_Struct(monitor, struct rb_monitor, &monitor_data_type, mc);
+    return mc;
+}
+
+static int
+mc_owner_p(struct rb_monitor *mc)
+{
+    return mc->owner == rb_thread_current();
+}
+
+static VALUE
+monitor_try_enter(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+
+    if (!mc_owner_p(mc)) {
+        if (!rb_mutex_trylock(mc->mutex)) {
+            return Qfalse;
+        }
+        RB_OBJ_WRITE(monitor, &mc->owner, rb_thread_current());
+        mc->count = 0;
+    }
+    mc->count += 1;
+    return Qtrue;
+}
+
+static VALUE
+monitor_enter(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    if (!mc_owner_p(mc)) {
+        rb_mutex_lock(mc->mutex);
+        RB_OBJ_WRITE(monitor, &mc->owner, rb_thread_current());
+        mc->count = 0;
+    }
+    mc->count++;
+    return Qnil;
+}
+
+static VALUE
+monitor_exit(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    mc->count--;
+    if (mc->count == 0) {
+        RB_OBJ_WRITE(monitor, &mc->owner, Qnil);
+        rb_mutex_unlock(mc->mutex);
+    }
+    return Qnil;
+}
+
+static VALUE
+monitor_locked_p(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    return rb_mutex_locked_p(mc->mutex);
+}
+
+static VALUE
+monitor_owned_p(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    return (rb_mutex_locked_p(mc->mutex) && mc_owner_p(mc)) ? Qtrue : Qfalse;
+}
+
+static VALUE
+monitor_check_owner(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    if (!mc_owner_p(mc)) {
+        rb_raise(rb_eThreadError, "current thread not owner");
+    }
+    return Qnil;
+}
+
+static VALUE
+monitor_enter_for_cond(VALUE monitor, VALUE count)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    RB_OBJ_WRITE(monitor, &mc->owner, rb_thread_current());
+    mc->count = NUM2LONG(count);
+    return Qnil;
+}
+
+static VALUE
+monitor_exit_for_cond(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    long cnt = mc->count;
+    RB_OBJ_WRITE(monitor, &mc->owner, Qnil);
+    mc->count = 0;
+    return LONG2NUM(cnt);
+}
+
+static VALUE
+monitor_mutex_for_cond(VALUE monitor)
+{
+    struct rb_monitor *mc = monitor_ptr(monitor);
+    return mc->mutex;
+}
+
+static VALUE
+monitor_sync_body(VALUE monitor)
+{
+    return rb_yield_values(0);
+}
+
+static VALUE
+monitor_sync_ensure(VALUE monitor)
+{
+    return monitor_exit(monitor);
+}
+
+static VALUE
+monitor_synchronize(VALUE monitor)
+{
+    monitor_enter(monitor);
+    return rb_ensure(monitor_sync_body, monitor, monitor_sync_ensure, monitor);
+}
+
+void
+Init_monitor(void)
+{
+    VALUE rb_cMonitor = rb_define_class("Monitor", rb_cObject);
+    rb_define_alloc_func(rb_cMonitor, monitor_alloc);
+
+    rb_define_method(rb_cMonitor, "try_enter", monitor_try_enter, 0);
+    rb_define_method(rb_cMonitor, "enter", monitor_enter, 0);
+    rb_define_method(rb_cMonitor, "exit", monitor_exit, 0);
+    rb_define_method(rb_cMonitor, "synchronize", monitor_synchronize, 0);
+
+    /* internal methods for MonitorMixin */
+    rb_define_method(rb_cMonitor, "mon_locked?", monitor_locked_p, 0);
+    rb_define_method(rb_cMonitor, "mon_check_owner", monitor_check_owner, 0);
+    rb_define_method(rb_cMonitor, "mon_owned?", monitor_owned_p, 0);
+
+    /* internal methods for MonitorMixin::ConditionalVariable */
+    rb_define_private_method(rb_cMonitor, "enter_for_cond", monitor_enter_for_cond, 1);
+    rb_define_private_method(rb_cMonitor, "exit_for_cond", monitor_exit_for_cond, 0);
+    rb_define_private_method(rb_cMonitor, "mutex_for_cond", monitor_mutex_for_cond, 0);
+}

test/monitor/test_monitor.rb

@@ -273,24 +273,24 @@ class TestMonitor < Test::Unit::TestCase
   end
 
   def test_wait_interruption
-    queue = Queue.new
     cond = @monitor.new_cond
-    @monitor.define_singleton_method(:mon_enter_for_cond) do |*args|
-      queue.deq
-      super(*args)
-    end
+
     th = Thread.start {
       @monitor.synchronize do
         begin
           cond.wait(0.1)
+          @monitor.mon_owned?
         rescue Interrupt
-          @monitor.instance_variable_get(:@mon_owner)
+          @monitor.mon_owned?
         end
       end
     }
     sleep(0.1)
     th.raise(Interrupt)
-    queue.enq(nil)
-    assert_equal th, th.value
+
+    begin
+      assert_equal true, th.value
+    rescue Interrupt
+    end
   end
 end