Use io/wait on platforms where it's available

IO.select is an expensive call, because it has to build an fd_set (large
bitfield) from an array each time we invoke it.

We're just interested in IO readiness, so on Ruby 2.0+ we can use the io/wait
API instead, which adds wait_readable/wait_writable to IO objects.

Author: tarcieri

.rubocop.yml

@@ -1,3 +1,6 @@
+AllCops:
+  DisplayCopNames: true
+
 Metrics/BlockNesting:
   Max: 2
 

lib/http/timeout/global.rb

@@ -104,16 +104,32 @@ def perform_io
         :eof
       end
 
-      # Wait for a socket to become readable
-      def wait_readable_or_timeout
-        IO.select([@socket], nil, nil, time_left)
-        log_time
-      end
+      if RUBY_VERSION < "2.0.0"
+        # Wait for a socket to become readable
+        def wait_readable_or_timeout
+          IO.select([@socket], nil, nil, time_left)
+          log_time
+        end
 
-      # Wait for a socket to become writable
-      def wait_writable_or_timeout
-        IO.select(nil, [@socket], nil, time_left)
-        log_time
+        # Wait for a socket to become writable
+        def wait_writable_or_timeout
+          IO.select(nil, [@socket], nil, time_left)
+          log_time
+        end
+      else
+        require "io/wait"
+
+        # Wait for a socket to become readable
+        def wait_readable_or_timeout
+          @socket.to_io.wait_readable(time_left)
+          log_time
+        end
+
+        # Wait for a socket to become writable
+        def wait_writable_or_timeout
+          @socket.to_io.wait_writable(time_left)
+          log_time
+        end
       end
 
       # Due to the run/retry nature of nonblocking I/O, it's easier to keep track of time

lib/http/timeout/null.rb

@@ -50,26 +50,43 @@ def write(data)
       end
       alias_method :<<, :write
 
+      # These cops can be re-eanbled after we go Ruby 2.0+ only
+      # rubocop:disable Lint/UselessAccessModifier, Metrics/BlockNesting
+
       private
 
-      # Retry reading
-      def rescue_readable
-        yield
-      rescue IO::WaitReadable
-        if IO.select([socket], nil, nil, read_timeout)
-          retry
-        else
+      if RUBY_VERSION < "2.0.0"
+        # Retry reading
+        def rescue_readable
+          yield
+        rescue IO::WaitReadable
+          retry if IO.select([socket], nil, nil, read_timeout)
+          raise TimeoutError, "Read timed out after #{read_timeout} seconds"
+        end
+
+        # Retry writing
+        def rescue_writable
+          yield
+        rescue IO::WaitWritable
+          retry if IO.select(nil, [socket], nil, write_timeout)
+          raise TimeoutError, "Write timed out after #{write_timeout} seconds"
+        end
+      else
+        require "io/wait"
+
+        # Retry reading
+        def rescue_readable
+          yield
+        rescue IO::WaitReadable
+          retry if socket.to_io.wait_readable(read_timeout)
           raise TimeoutError, "Read timed out after #{read_timeout} seconds"
         end
-      end
 
-      # Retry writing
-      def rescue_writable
-        yield
-      rescue IO::WaitWritable
-        if IO.select(nil, [socket], nil, write_timeout)
-          retry
-        else
+        # Retry writing
+        def rescue_writable
+          yield
+        rescue IO::WaitWritable
+          retry if socket.to_io.wait_writable(write_timeout)
           raise TimeoutError, "Write timed out after #{write_timeout} seconds"
         end
       end

lib/http/timeout/per_operation.rb

@@ -59,14 +59,17 @@ def write(data)
         # Read data from the socket
         def readpartial(size)
           loop do
-            result = socket.read_nonblock(size, :exception => false)
+            result = rescue_readable do
+              socket.read_nonblock(size, :exception => false)
+            end
+
             if result.nil?
               return :eof
             elsif result != :wait_readable
               return result
             end
 
-            unless IO.select([socket], nil, nil, read_timeout)
+            unless socket.to_io.wait_readable(read_timeout)
               fail TimeoutError, "Read timed out after #{read_timeout} seconds"
             end
           end
@@ -75,10 +78,13 @@ def readpartial(size)
         # Write data to the socket
         def write(data)
           loop do
-            result = socket.write_nonblock(data, :exception => false)
+            result = rescue_writable do
+              socket.write_nonblock(data, :exception => false)
+            end
+
             return result unless result == :wait_writable
 
-            unless IO.select(nil, [socket], nil, write_timeout)
+            unless socket.to_io.wait_writable(write_timeout)
               fail TimeoutError, "Read timed out after #{write_timeout} seconds"
             end
           end