Add sys.pump

doc/api.markdown

@@ -837,6 +837,14 @@ Example of inspecting all properties of the `sys` object:
     sys.puts(sys.inspect(sys, true, null));
 
 
+### sys.pump(readableStream, writeableStream, [callback])
+
+Experimental
+
+Read the data from `readableStream` and send it to the `writableStream`.
+When `writeableStream.write(data)` returns `false` `readableStream` will be
+paused until the `drain` event occurs on the `writableStream`. `callback` is
+called when `writableStream` is closed.
 
 
 ## Timers

lib/sys.js

@@ -283,6 +283,24 @@ exports.exec = function () {
 };
 
 
+exports.pump = function (readStream, writeStream, callback) {
+  readStream.addListener("data", function (chunk) {
+    if (writeStream.write(chunk) === false) readStream.pause();
+  });
+
+  writeStream.addListener("drain", function () {
+    readStream.resume();
+  });
+
+  readStream.addListener("end", function () {
+    writeStream.end();
+  });
+
+  readStream.addListener("close", function () {
+    if (callback) callback();
+  });
+};
+
 /**
  * Inherit the prototype methods from one constructor into another.
  *

test/simple/test-pump-file2tcp.js

@@ -0,0 +1,43 @@
+require("../common");
+net = require("net");
+fs = require("fs");
+sys = require("sys");
+path = require("path");
+fn = path.join(fixturesDir, 'elipses.txt');
+
+expected = fs.readFileSync(fn, 'utf8');
+
+server = net.createServer(function (stream) {
+  error('pump!');
+  sys.pump(fs.createReadStream(fn), stream, function () {
+    error('server stream close');
+    error('server close');
+    server.close();
+  });
+});
+
+server.listen(PORT, function () {
+  conn = net.createConnection(PORT);
+  conn.setEncoding('utf8');
+  conn.addListener("data", function (chunk) {
+    error('recv data! nchars = ' + chunk.length);
+    buffer += chunk;
+  });
+
+  conn.addListener("end", function () {
+    conn.end();
+  });
+  conn.addListener("close", function () {
+    error('client connection close');
+  });
+});
+
+var buffer = '';
+count = 0;
+
+server.addListener('listening', function () {
+});
+
+process.addListener('exit', function () {
+  assert.equal(expected, buffer);
+});