Bug 522416 - Add an asyncFetch method on NetUtil.jsm

This adds an asyncFetch method on NetUtil that will open a channel
asynchronously and provide the consumer with an input stream upon completion.
r=bz
sr=vlad

--HG--
extra : rebase_source : bbeffb5669ba0f040773fca5faca28494982ff94

netwerk/base/src/NetUtil.jsm

@@ -53,6 +53,8 @@ const Ci = Components.interfaces;
 const Cc = Components.classes;
 const Cr = Components.results;
 
+const PR_UINT32_MAX = 0xffffffff;
+
 ////////////////////////////////////////////////////////////////////////////////
 //// NetUtil Object
 
@@ -125,6 +127,49 @@ const NetUtil = {
         return copier;
     },
 
+    /**
+     * Asynchronously opens a channel and fetches the response.  The provided
+     * callback will get an input stream containing the response, and the result
+     * code.
+     *
+     * @param aChannel
+     *        The nsIChannel to open.
+     * @param aCallback
+     *        The callback function that will be notified upon completion.  It
+     *        will get two arguments:
+     *        1) An nsIInputStream containing the data from the channel, if any.
+     *        2) The status code from opening the channel.
+     */
+    asyncFetch: function NetUtil_asyncOpen(aChannel, aCallback)
+    {
+        if (!aChannel || !aCallback) {
+            let exception = new Components.Exception(
+                "Must have a channel and a callback",
+                Cr.NS_ERROR_INVALID_ARG,
+                Components.stack.caller
+            );
+            throw exception;
+        }
+
+        // Create a pipe that will create our output stream that we can use once
+        // we have gotten all the data.
+        let pipe = Cc["@mozilla.org/pipe;1"].
+                   createInstance(Ci.nsIPipe);
+        pipe.init(false, false, 0, PR_UINT32_MAX, null);
+
+        // Create a listener that will give data to the pipe's output stream.
+        let listener = Cc["@mozilla.org/network/simple-stream-listener;1"].
+                       createInstance(Ci.nsISimpleStreamListener);
+        listener.init(pipe.outputStream, {
+            onStartRequest: function(aRequest, aContext) {},
+            onStopRequest: function(aRequest, aContext, aStatusCode) {
+                aCallback(pipe.inputStream, aStatusCode);
+            }
+        });
+
+        aChannel.asyncOpen(listener, null);
+    },
+
     /**
      * Constructs a new URI for the given spec, character set, and base URI.
      *

netwerk/test/unit/test_NetUtil.js

@@ -41,10 +41,9 @@
  * This file tests the methods on NetUtil.jsm.
  */
 
+do_load_httpd_js();
+
 Components.utils.import("resource://gre/modules/NetUtil.jsm");
-const Cc = Components.classes;
-const Ci = Components.interfaces;
-const Cr = Components.results;
 
 ////////////////////////////////////////////////////////////////////////////////
 //// Helper Methods
@@ -179,6 +178,66 @@ function test_ioService()
   run_next_test();
 }
 
+function test_asyncFetch_no_channel()
+{
+  try {
+    NetUtil.asyncFetch(null, function() { });
+    do_throw("should throw!");
+  }
+  catch (e) {
+    do_check_eq(e.result, Cr.NS_ERROR_INVALID_ARG);
+  }
+
+  run_next_test();
+}
+
+function test_asyncFetch_no_callback()
+{
+  try {
+    NetUtil.asyncFetch({ });
+    do_throw("should throw!");
+  }
+  catch (e) {
+    do_check_eq(e.result, Cr.NS_ERROR_INVALID_ARG);
+  }
+
+  run_next_test();
+}
+
+function test_asyncFetch()
+{
+  const TEST_DATA = "this is a test string";
+
+  // Start the http server, and register our handler.
+  let server = new nsHttpServer();
+  server.registerPathHandler("/test", function(aRequest, aResponse) {
+    aResponse.setStatusLine(aRequest.httpVersion, 200, "OK");
+    aResponse.setHeader("Content-Type", "text/plain", false);
+    aResponse.write(TEST_DATA);
+  });
+  server.start(4444);
+
+  // Create our channel.
+  let channel = NetUtil.ioService.
+                newChannel("http://localhost:4444/test", null, null);
+
+  // Open our channel asynchronously.
+  NetUtil.asyncFetch(channel, function(aInputStream, aResult) {
+    // Check that we had success.
+    do_check_true(Components.isSuccessCode(aResult));
+
+    // Check that we got the right data.
+    do_check_eq(aInputStream.available(), TEST_DATA.length);
+    let is = Cc["@mozilla.org/scriptableinputstream;1"].
+             createInstance(Ci.nsIScriptableInputStream);
+    is.init(aInputStream);
+    let result = is.read(TEST_DATA.length);
+    do_check_eq(TEST_DATA, result);
+
+    server.stop(run_next_test);
+  });
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //// Test Runner
 
@@ -188,6 +247,9 @@ let tests = [
   test_newURI_no_spec_throws,
   test_newURI,
   test_ioService,
+  test_asyncFetch_no_channel,
+  test_asyncFetch_no_callback,
+  test_asyncFetch,
 ];
 let index = 0;