socket: allow explicit buffer for recv and recv_nonblock

This reduces GC overhead and makes the API more consistent
with IO#read and IO#read_nonblock.

* ext/socket/basicsocket.c (bsock_recv): document outbuf
* ext/socket/unixsocket.c (unix_recvfrom): ditto
* ext/socket/init.c (rsock_strbuf, recvfrom_locktmp): new functions
  (rsock_s_recvfrom): support destination buffer as 3rd arg
  (rsock_s_recvfrom_nonblock): ditto
* string.c (rb_str_locktmp_ensure): export for internal ext
* test/socket/test_nonblock.rb: test recv_nonblock
* test/socket/test_unix.rb: test recv
  [ruby-core:69543] [Feature #11242]

Benchmark results:

             user     system      total        real
alloc    0.130000   0.280000   0.410000 (  0.420656)
extbuf   0.100000   0.220000   0.320000 (  0.318708)

-------------------8<--------------------
require 'socket'
require 'benchmark'
nr = 100000
msg = ' ' * 16384
size = msg.bytesize
buf = ' ' * size
UNIXSocket.pair(:DGRAM) do |a, b|
  Benchmark.bmbm do |x|
    x.report('alloc') do
      nr.times do
        b.send(msg, 0)
        a.recv(size, 0)
      end
    end

    x.report('extbuf') do
      nr.times do
        b.send(msg, 0)
        a.recv(size, 0, buf)
      end
    end
  end
end

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50912 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 10 insertions, 0 deletions

diff --git a/test/socket/test_nonblock.rb b/test/socket/test_nonblock.rb
index 4e14c9355a..93f463daf9 100644
--- a/test/socket/test_nonblock.rb
+++ b/test/socket/test_nonblock.rb
@@ -128,6 +128,16 @@ class TestSocketNonblock < Test::Unit::TestCase
     }
     mesg = u1.recv_nonblock(100)
     assert_equal("", mesg)
+
+    buf = "short"
+    out = "hello world" * 4
+    out.freeze
+    u2.send(out, 0, u1.getsockname)
+    IO.select [u1]
+    rv = u1.recv_nonblock(100, 0, buf)
+    assert_equal rv.object_id, buf.object_id
+    assert_equal out, rv
+    assert_equal out, buf
   ensure
     u1.close if u1
     u2.close if u2