add `#kgio_writev` and `#kgio_trywritev`

Add methods for using writev(2) syscall for sending array of string in
a single syscall. This is more efficient than concatenating strings on
Ruby side or sending them one by one.
`#kgio_trywritev` returns array of strings which are not sent to the
socket. If there were objects other than string, they could be converted
using `#to_s` method, but this is not strictly applied, cause
`#kgio_*writev` tries to write at most `sysconf(_SC_IOV_MAX)` items
at once (for Linux its value is 1024). First string of returned array
could be part of string from array, so that you should assume it is not
in consistent state.

`#kgio_writev` semantic differs a bit from `#kgio_write` in term of
buffers mutability: currently `#kgio_write` tries to follow string changes
made concurrently, but `#kgio_writev` works with array's lightweight copy.

Signed-off-by: Eric Wong <normalperson@yhbt.net>

1 files changed, 128 insertions, 0 deletions

diff --git a/test/lib_read_write.rb b/test/lib_read_write.rb
index 6f345cb..04d6fc6 100644
--- a/test/lib_read_write.rb
+++ b/test/lib_read_write.rb
@@ -21,6 +21,14 @@ module LibReadWriteTest
     assert_nil @wr.kgio_trywrite("")
   end
 
+  def test_writev_empty
+    assert_nil @wr.kgio_writev([])
+  end
+
+  def test_trywritev_empty
+    assert_nil @wr.kgio_trywritev([])
+  end
+
   def test_read_zero
     assert_equal "", @rd.kgio_read(0)
     buf = "foo"
@@ -116,6 +124,28 @@ module LibReadWriteTest
     assert false, "should never get here (line:#{__LINE__})"
   end
 
+  def test_writev_closed
+    @rd.close
+    begin
+      loop { @wr.kgio_writev ["HI"] }
+    rescue Errno::EPIPE, Errno::ECONNRESET => e
+      assert_equal [], e.backtrace
+      return
+    end
+    assert false, "should never get here (line:#{__LINE__})"
+  end
+
+  def test_trywritev_closed
+    @rd.close
+    begin
+      loop { @wr.kgio_trywritev ["HI"] }
+    rescue Errno::EPIPE, Errno::ECONNRESET => e
+      assert_equal [], e.backtrace
+      return
+    end
+    assert false, "should never get here (line:#{__LINE__})"
+  end
+
   def test_trywrite_full
     buf = "\302\251" * 1024 * 1024
     buf2 = ""
@@ -153,6 +183,43 @@ module LibReadWriteTest
     assert_equal '8ff79d8115f9fe38d18be858c66aa08a1cc27a66', t.value
   end
 
+  def test_trywritev_full
+    buf = ["\302\251" * 128] * 8 * 1024
+    buf2 = ""
+    dig = Digest::SHA1.new
+    t = Thread.new do
+      sleep 1
+      nr = 0
+      begin
+        dig.update(@rd.readpartial(4096, buf2))
+        nr += buf2.size
+      rescue EOFError
+        break
+      rescue => e
+      end while true
+      dig.hexdigest
+    end
+    50.times do
+      wr = buf
+      begin
+        rv = @wr.kgio_trywritev(wr)
+        case rv
+        when Array
+          wr = rv
+        when :wait_readable
+          assert false, "should never get here line=#{__LINE__}"
+        when :wait_writable
+          IO.select(nil, [ @wr ])
+        else
+          wr = false
+        end
+      end while wr
+    end
+    @wr.close
+    t.join
+    assert_equal '8ff79d8115f9fe38d18be858c66aa08a1cc27a66', t.value
+  end
+
   def test_write_conv
     assert_equal nil, @wr.kgio_write(10)
     assert_equal "10", @rd.kgio_read(2)
@@ -214,6 +281,19 @@ module LibReadWriteTest
     tmp.each { |count| assert_equal nil, count }
   end
 
+  def test_trywritev_return_wait_writable
+    tmp = []
+    tmp << @wr.kgio_trywritev(["HI"]) until tmp[-1] == :wait_writable
+    assert :wait_writable === tmp[-1]
+    assert(!(:wait_readable === tmp[-1]))
+    assert_equal :wait_writable, tmp.pop
+    assert tmp.size > 0
+    penultimate = tmp.pop
+    assert(penultimate == "I" || penultimate == nil)
+    assert tmp.size > 0
+    tmp.each { |count| assert_equal nil, count }
+  end
+
   def test_tryread_extra_buf_eagain_clears_buffer
     tmp = "hello world"
     rv = @rd.kgio_tryread(2, tmp)
@@ -248,6 +328,36 @@ module LibReadWriteTest
     assert_equal buf, readed
   end
 
+  def test_monster_trywritev
+    buf, start = [], 0
+    while start < RANDOM_BLOB.size
+      s = RANDOM_BLOB[start, 1000]
+      start += s.size
+      buf << s
+    end
+    rv = @wr.kgio_trywritev(buf)
+    assert_kind_of Array, rv
+    rv = rv.join
+    assert rv.size < RANDOM_BLOB.size
+    @rd.nonblock = false
+    assert_equal(RANDOM_BLOB, @rd.read(RANDOM_BLOB.size - rv.size) + rv)
+  end
+
+  def test_monster_writev
+    buf, start = [], 0
+    while start < RANDOM_BLOB.size
+      s = RANDOM_BLOB[start, 10000]
+      start += s.size
+      buf << s
+    end
+    thr = Thread.new { @wr.kgio_writev(buf) }
+    @rd.nonblock = false
+    readed = @rd.read(RANDOM_BLOB.size)
+    thr.join
+    assert_nil thr.value
+    assert_equal RANDOM_BLOB, readed
+  end
+
   def test_monster_write_wait_writable
     @wr.instance_variable_set :@nr, 0
     def @wr.kgio_wait_writable
@@ -256,6 +366,7 @@ module LibReadWriteTest
     end
     buf = "." * 1024 * 1024 * 10
     thr = Thread.new { @wr.kgio_write(buf) }
+    Thread.pass until thr.stop?
     readed = @rd.read(buf.size)
     thr.join
     assert_nil thr.value
@@ -263,6 +374,23 @@ module LibReadWriteTest
     assert @wr.instance_variable_get(:@nr) > 0
   end
 
+  def test_monster_writev_wait_writable
+    @wr.instance_variable_set :@nr, 0
+    def @wr.kgio_wait_writable
+      @nr += 1
+      IO.select(nil, [self])
+    end
+    buf = ["." * 1024] * 1024 * 10
+    buf_size = buf.inject(0){|c, s| c + s.size}
+    thr = Thread.new { @wr.kgio_writev(buf) }
+    Thread.pass until thr.stop?
+    readed = @rd.read(buf_size)
+    thr.join
+    assert_nil thr.value
+    assert_equal buf.join, readed
+    assert @wr.instance_variable_get(:@nr) > 0
+  end
+
   def test_wait_readable_ruby_default
     elapsed = 0
     foo = nil