[sleepy.penguin] [PATCH 04/17] fork-safe "to_io" in high-level epoll/kqueue

[Eric Wong <normalperson@yhbt.net>]

We need to validate the underlying IO object before using
it in a forked child.
---
 lib/sleepy_penguin/epoll.rb  | 51 ++++++++++++++++++++++++--------------------
 lib/sleepy_penguin/kqueue.rb | 39 ++++++++++++++++++---------------
 2 files changed, 50 insertions(+), 40 deletions(-)

diff --git a/lib/sleepy_penguin/epoll.rb b/lib/sleepy_penguin/epoll.rb
index 8d78e46..f29189a 100644
--- a/lib/sleepy_penguin/epoll.rb
+++ b/lib/sleepy_penguin/epoll.rb
@@ -1,45 +1,50 @@
 require 'thread'
 class SleepyPenguin::Epoll
 
-  # Epoll objects may be watched by IO.select and similar methods
-  attr_reader :to_io
-
   # call-seq:
   #     SleepyPenguin::Epoll.new([flags]) -> Epoll object
   #
   # Creates a new Epoll object with an optional +flags+ argument.
   # +flags+ may currently be +:CLOEXEC+ or +0+ (or +nil+).
   def initialize(create_flags = nil)
-    @to_io = SleepyPenguin::Epoll::IO.new(create_flags)
+    @io = SleepyPenguin::Epoll::IO.new(create_flags)
     @mtx = Mutex.new
     @events = []
     @marks = []
     @pid = $$
     @create_flags = create_flags
-    @copies = { @to_io => self }
+    @copies = { @io => self }
   end
 
   def __ep_reinit # :nodoc:
     @events.clear
     @marks.clear
-    @to_io = SleepyPenguin::Epoll::IO.new(@create_flags)
+    @io = SleepyPenguin::Epoll::IO.new(@create_flags)
   end
 
   # auto-reinitialize the Epoll object after forking
   def __ep_check # :nodoc:
     return if @pid == $$
-    return if @to_io.closed?
+    return if @io.closed?
     objects = @copies.values
     @copies.each_key { |epio| epio.close }
     @copies.clear
     __ep_reinit
     objects.each do |obj|
-      io_dup = @to_io.dup
+      io_dup = @io.dup
       @copies[io_dup] = obj
     end
     @pid = $$
   end
 
+  # Epoll objects may be watched by IO.select and similar methods
+  def to_io
+    @mtx.synchronize do
+      __ep_check
+      @io
+    end
+  end
+
   # Calls epoll_wait(2) and yields Integer +events+ and IO objects watched
   # for.  +maxevents+ is the maximum number of events to process at once,
   # lower numbers may prevent starvation when used by epoll_wait in multiple
@@ -59,7 +64,7 @@ def wait(maxevents = 64, timeout = nil)
     # we keep a snapshot of @marks around in case another thread closes
     # the IO while it is being transferred to userspace.  We release mtx
     # so another thread may add events to us while we're sleeping.
-    @to_io.epoll_wait(maxevents, timeout) { |events, io| yield(events, io) }
+    @io.epoll_wait(maxevents, timeout) { |events, io| yield(events, io) }
   ensure
     # hopefully Ruby does not optimize this array away...
     snapshot[0]
@@ -72,7 +77,7 @@ def add(io, events)
     events = __event_flags(events)
     @mtx.synchronize do
       __ep_check
-      @to_io.epoll_ctl(CTL_ADD, io, events)
+      @io.epoll_ctl(CTL_ADD, io, events)
       @events[fd] = events
       @marks[fd] = io
     end
@@ -87,7 +92,7 @@ def del(io)
     fd = io.to_io.fileno
     @mtx.synchronize do
       __ep_check
-      @to_io.epoll_ctl(CTL_DEL, io, 0)
+      @io.epoll_ctl(CTL_DEL, io, 0)
       @events[fd] = @marks[fd] = nil
     end
     0
@@ -110,7 +115,7 @@ def delete(io)
       __ep_check
       cur_io = @marks[fd]
       return if nil == cur_io || cur_io.to_io.closed?
-      @to_io.epoll_ctl(CTL_DEL, io, 0)
+      @io.epoll_ctl(CTL_DEL, io, 0)
       @events[fd] = @marks[fd] = nil
     end
     io
@@ -127,7 +132,7 @@ def mod(io, events)
     fd = io.to_io.fileno
     @mtx.synchronize do
       __ep_check
-      @to_io.epoll_ctl(CTL_MOD, io, events)
+      @io.epoll_ctl(CTL_MOD, io, events)
       @marks[fd] = io # may be a different object with same fd/file
       @events[fd] = events
     end
@@ -159,18 +164,18 @@ def set(io, events)
         cur_events = @events[fd]
         return 0 if (cur_events & ONESHOT) == 0 && cur_events == events
         begin
-          @to_io.epoll_ctl(CTL_MOD, io, events)
+          @io.epoll_ctl(CTL_MOD, io, events)
         rescue Errno::ENOENT
           warn "epoll event cache failed (mod -> add)"
-          @to_io.epoll_ctl(CTL_ADD, io, events)
+          @io.epoll_ctl(CTL_ADD, io, events)
           @marks[fd] = io
         end
       else
         begin
-          @to_io.epoll_ctl(CTL_ADD, io, events)
+          @io.epoll_ctl(CTL_ADD, io, events)
         rescue Errno::EEXIST
           warn "epoll event cache failed (add -> mod)"
-          @to_io.epoll_ctl(CTL_MOD, io, events)
+          @io.epoll_ctl(CTL_MOD, io, events)
         end
         @marks[fd] = io
       end
@@ -186,8 +191,8 @@ def set(io, events)
   # Raises IOError if object is already closed.
   def close
     @mtx.synchronize do
-      @copies.delete(@to_io)
-      @to_io.close
+      @copies.delete(@io)
+      @io.close
     end
   end
 
@@ -197,7 +202,7 @@ def close
   # Returns whether or not an Epoll object is closed.
   def closed?
     @mtx.synchronize do
-      @to_io.closed?
+      @io.closed?
     end
   end
 
@@ -254,9 +259,9 @@ def initialize_copy(src) # :nodoc:
     @mtx.synchronize do
       __ep_check
       rv = super
-      unless @to_io.closed?
-        @to_io = @to_io.dup
-        @copies[@to_io] = self
+      unless @io.closed?
+        @io = @io.dup
+        @copies[@io] = self
       end
       rv
     end
diff --git a/lib/sleepy_penguin/kqueue.rb b/lib/sleepy_penguin/kqueue.rb
index fbbde8a..1eeb641 100644
--- a/lib/sleepy_penguin/kqueue.rb
+++ b/lib/sleepy_penguin/kqueue.rb
@@ -8,23 +8,28 @@
 # Events registered to a Kqueue object cannot be shared across fork
 # due to the underlying implementation of kqueue in *BSDs.
 class SleepyPenguin::Kqueue
-  # Kqueue objects may be watched by IO.select and similar methods
-  attr_reader :to_io
-
   def initialize
-    @to_io = SleepyPenguin::Kqueue::IO.new
+    @io = SleepyPenguin::Kqueue::IO.new
     @mtx = Mutex.new
     @pid = $$
-    @copies = { @to_io => self }
+    @copies = { @io => self }
+  end
+
+  # Kqueue objects may be watched by IO.select and similar methods
+  def to_io
+    @mtx.synchronize do
+      __kq_check
+      @io
+    end
   end
 
   def __kq_reinit # :nodoc:
-    @to_io = SleepyPenguin::Kqueue::IO.new
+    @io = SleepyPenguin::Kqueue::IO.new
   end
 
   def __kq_check # :nodoc:
-    return if @pid == $$ || @to_io.closed?
-    unless @to_io.respond_to?(:autoclose=)
+    return if @pid == $$ || @io.closed?
+    unless @io.respond_to?(:autoclose=)
       raise RuntimeError,
        "Kqueue is not safe to use without IO#autoclose=, upgrade to Ruby 1.9+"
     end
@@ -35,7 +40,7 @@ def __kq_check # :nodoc:
     @copies.clear
     __kq_reinit
     objects.each do |obj|
-      io_dup = @to_io.dup
+      io_dup = @io.dup
       @copies[io_dup] = obj
     end
     @pid = $$
@@ -61,7 +66,7 @@ def kevent(changelist = nil, *args)
     end
 
     if block_given?
-      n = @to_io.kevent(changelist, *args) do |ident,filter,flags,
+      n = @io.kevent(changelist, *args) do |ident,filter,flags,
                                                fflags,data,udata|
         # This may raise and cause events to be lost,
         # that's the users' fault/problem
@@ -70,7 +75,7 @@ def kevent(changelist = nil, *args)
                                         fflags, data, udata)
       end
     else
-      n = @to_io.kevent(changelist, *args)
+      n = @io.kevent(changelist, *args)
     end
   end
 
@@ -78,9 +83,9 @@ def initialize_copy(src) # :nodoc:
     @mtx.synchronize do
       __kq_check
       rv = super
-      unless @to_io.closed?
-        @to_io = @to_io.dup
-        @copies[@to_io] = self
+      unless @io.closed?
+        @io = @io.dup
+        @copies[@io] = self
       end
       rv
     end
@@ -93,8 +98,8 @@ def initialize_copy(src) # :nodoc:
   # Raises IOError if object is already closed.
   def close
     @mtx.synchronize do
-      @copies.delete(@to_io)
-      @to_io.close
+      @copies.delete(@io)
+      @io.close
     end
   end
 
@@ -104,7 +109,7 @@ def close
   # Returns whether or not an Kqueue object is closed.
   def closed?
     @mtx.synchronize do
-      @to_io.closed?
+      @io.closed?
     end
   end
 end
-- 
1.8.2.1.367.gc875ca7