[PATCH] mogilefs/socket/pure_ruby: use IO#wait_*able

[Eric Wong <normalperson@yhbt.net>]

IO#wait_*able methods may use the more efficient ppoll syscall under
Linux to avoid performance penalties with high-numbered FDs.  Use
them if available.  IO#wait_readable has been around since the 1.8
days at least, and IO#wait_writable was added in Ruby 2.0.0
---
 lib/mogilefs/socket/pure_ruby.rb | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/lib/mogilefs/socket/pure_ruby.rb b/lib/mogilefs/socket/pure_ruby.rb
index 8833d22..7530a40 100644
--- a/lib/mogilefs/socket/pure_ruby.rb
+++ b/lib/mogilefs/socket/pure_ruby.rb
@@ -1,5 +1,6 @@
 # -*- encoding: binary -*-
 # internal implementation details here, do not rely on them in your code
+require 'io/wait'
 
 class MogileFS::Socket < Socket
   include MogileFS::SocketCommon
@@ -15,16 +16,20 @@ class MogileFS::Socket < Socket
 
   def self.tcp(host, port, timeout = 5)
     sock = start(host, port)
-    unless IO.select(nil, [ sock ], nil, timeout)
+    unless sock.wait_writable(timeout)
       sock.close
       raise MogileFS::Timeout, 'socket connect timeout'
     end
     sock
   end
 
+  def wait_writable(timeout)
+    IO.select(nil, [ self ], nil, timeout)
+  end unless self.instance_methods.include?(:wait_writable) # Ruby <2.0.0
+
   def timed_read(len, dst = "", timeout = 5)
     begin
-      IO.select([self], nil, nil, timeout) or unreadable_socket!(timeout)
+      wait_readable(timeout) or unreadable_socket!(timeout)
       return read_nonblock(len, dst)
     rescue Errno::EAGAIN
     rescue EOFError
@@ -34,7 +39,7 @@ class MogileFS::Socket < Socket
 
   def timed_peek(len, dst, timeout = 5)
     begin
-      IO.select([self], nil, nil, timeout) or unreadable_socket!(timeout)
+      wait_readable(timeout) or unreadable_socket!(timeout)
       rc = recv_nonblock(len, Socket::MSG_PEEK)
       return rc.empty? ? nil : dst.replace(rc)
     rescue Errno::EAGAIN
@@ -61,8 +66,7 @@ class MogileFS::Socket < Socket
         buf = buf.slice(rc, buf.bytesize)
       end
     rescue Errno::EAGAIN
-      IO.select(nil, [self], nil, timeout) or
-        request_truncated!(written, expect, timeout)
+      wait_writable(timeout) or request_truncated!(written, expect, timeout)
     end while true
   end
 end
-- 
EW