dgram: support dgram.send with multiple buffers

Added ability to dgram.send to send multiple buffers, _writev style.
The offset and length parameters in dgram.send are now optional.
Refactored the dgram benchmarks, and seperated them from net.
Added docs for the new signature.

Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Saúl Ibarra Corretgé <saghul@gmail.com>
Fixes: https://github.com/nodejs/node/issues/4302
PR-URL: https://github.com/nodejs/node/pull/4374

1 files changed, 70 insertions, 0 deletions

diff --git a/benchmark/dgram/multi-buffer.js b/benchmark/dgram/multi-buffer.js
new file mode 100644
index 0000000000..37fb5d1a8e
--- /dev/null
+++ b/benchmark/dgram/multi-buffer.js
@@ -0,0 +1,70 @@
+// test UDP send/recv throughput with the multi buffer API
+'use strict';
+
+const common = require('../common.js');
+const PORT = common.PORT;
+
+// `num` is the number of send requests to queue up each time.
+// Keep it reasonably high (>10) otherwise you're benchmarking the speed of
+// event loop cycles more than anything else.
+var bench = common.createBenchmark(main, {
+  len: [64, 256, 1024],
+  num: [100],
+  chunks: [1, 2, 4, 8],
+  type: ['send', 'recv'],
+  dur: [5]
+});
+
+var dur;
+var len;
+var num;
+var type;
+var chunk;
+var chunks;
+var encoding;
+
+function main(conf) {
+  dur = +conf.dur;
+  len = +conf.len;
+  num = +conf.num;
+  type = conf.type;
+  chunks = +conf.chunks;
+
+  chunk = []
+  for (var i = 0; i < chunks; i++) {
+    chunk.push(new Buffer(Math.round(len / chunks)));
+  }
+
+  server();
+}
+
+var dgram = require('dgram');
+
+function server() {
+  var sent = 0;
+  var received = 0;
+  var socket = dgram.createSocket('udp4');
+
+  function onsend() {
+    if (sent++ % num == 0)
+      for (var i = 0; i < num; i++)
+        socket.send(chunk, PORT, '127.0.0.1', onsend);
+  }
+
+  socket.on('listening', function() {
+    bench.start();
+    onsend();
+
+    setTimeout(function() {
+      var bytes = (type === 'send' ? sent : received) * len;
+      var gbits = (bytes * 8) / (1024 * 1024 * 1024);
+      bench.end(gbits);
+    }, dur * 1000);
+  });
+
+  socket.on('message', function(buf, rinfo) {
+    received++;
+  });
+
+  socket.bind(PORT);
+}