Allows deferral of a URLRequest just before talking to the network, at

net/http/http_network_transaction_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/http/http_network_transaction.h"
 
 #include <math.h>  // ceil
 #include <stdarg.h>
 #include <string>
 #include <vector>
@@ skipping 386 matching lines @@
 
 INSTANTIATE_TEST_CASE_P(
     NextProto,
     HttpNetworkTransactionTest,
     testing::Values(kProtoDeprecatedSPDY2,
                     kProtoSPDY3, kProtoSPDY31, kProtoSPDY4a2,
                     kProtoHTTP2Draft04));
 
 namespace {
 
+class BeforeNetworkStartHandler {
+ public:
+  explicit BeforeNetworkStartHandler(bool defer)
+      : defer_on_before_network_start_(defer),
+        observed_before_network_start_(false) {}
+
+  void OnBeforeNetworkStart(bool* defer) {
+    *defer = defer_on_before_network_start_;
+    observed_before_network_start_ = true;
+  }
+
+  bool observed_before_network_start() const {
+    return observed_before_network_start_;
+  }
+
+ private:
+  const bool defer_on_before_network_start_;
+  bool observed_before_network_start_;
+
+  DISALLOW_COPY_AND_ASSIGN(BeforeNetworkStartHandler);
+};
+
 // Fill |str| with a long header list that consumes >= |size| bytes.
 void FillLargeHeadersString(std::string* str, int size) {
   const char* row =
       "SomeHeaderName: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\r\n";
   const int sizeof_row = strlen(row);
   const int num_rows = static_cast<int>(
       ceil(static_cast<float>(size) / sizeof_row));
   const int sizeof_data = num_rows * sizeof_row;
   DCHECK(sizeof_data >= size);
   str->reserve(sizeof_data);
@@ skipping 919 matching lines @@
     MockRead(SYNCHRONOUS, OK),  // EOF
     MockRead("HTTP/1.0 200 OK\r\n\r\n"),  // Should not be used
     MockRead("hello world"),
     MockRead(SYNCHRONOUS, OK),
   };
   SimpleGetHelperResult out = SimpleGetHelper(data_reads,
                                               arraysize(data_reads));
   EXPECT_EQ(ERR_EMPTY_RESPONSE, out.rv);
 }
 
+// Test that network access can be deferred and resumed.
+TEST_P(HttpNetworkTransactionTest, ThrottleBeforeNetworkStart) {
+  HttpRequestInfo request;
+  request.method = "GET";
+  request.url = GURL("http://www.google.com/");
+  request.load_flags = 0;
+
+  scoped_refptr<HttpNetworkSession> session(CreateSession(&session_deps_));
+  scoped_ptr<HttpTransaction> trans(
+      new HttpNetworkTransaction(DEFAULT_PRIORITY, session.get()));
+
+  // Defer on OnBeforeNetworkStart.
+  BeforeNetworkStartHandler net_start_handler(true);  // defer
+  trans->SetBeforeNetworkStartCallback(
+      base::Bind(&BeforeNetworkStartHandler::OnBeforeNetworkStart,
+                 base::Unretained(&net_start_handler)));
+
+  MockRead data_reads[] = {MockRead("HTTP/1.0 200 OK\r\n"),
+                           MockRead("Connection: keep-alive\r\n"),
+                           MockRead("Content-Length: 100\r\n\r\n"),
+                           MockRead("hello"),
+                           MockRead(SYNCHRONOUS, 0), };

[mmenke, 2014/01/07 19:44:05]

optional nit (x2):  I don't think I've seen this done much - whenever there's an
extra comma at the end, the close brace is generally put on the next line.

[jkarlin, 2014/01/07 20:10:03]

Huh, I wonder what's up with clang-format.

+  StaticSocketDataProvider data(data_reads, arraysize(data_reads), NULL, 0);
+  session_deps_.socket_factory->AddSocketDataProvider(&data);
+
+  TestCompletionCallback callback;
+
+  int rv = trans->Start(&request, callback.callback(), BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  base::MessageLoop::current()->RunUntilIdle();
+
+  // Should have deferred for network start.
+  EXPECT_TRUE(net_start_handler.observed_before_network_start());
+  EXPECT_EQ(LOAD_STATE_WAITING_FOR_DELEGATE, trans->GetLoadState());
+  EXPECT_TRUE(trans->GetResponseInfo() == NULL);
+
+  trans->ResumeNetworkStart();
+  rv = callback.WaitForResult();
+  EXPECT_EQ(OK, rv);
+  EXPECT_TRUE(trans->GetResponseInfo() != NULL);
+
+  scoped_refptr<IOBufferWithSize> io_buf(new IOBufferWithSize(100));
+  rv = trans->Read(io_buf.get(), io_buf->size(), callback.callback());
+  if (rv == ERR_IO_PENDING)
+    rv = callback.WaitForResult();
+  EXPECT_EQ(5, rv);
+  rv = trans->Read(io_buf.get(), io_buf->size(), callback.callback());
+  EXPECT_EQ(ERR_CONTENT_LENGTH_MISMATCH, rv);

[mmenke, 2014/01/07 19:44:05]

Any reason not to use a success case instead?  (OR as well?)

[jkarlin, 2014/01/07 20:10:03]

Done.

+
+  trans.reset();
+  base::MessageLoop::current()->RunUntilIdle();
+  EXPECT_EQ(0, GetIdleSocketCountInTransportSocketPool(session.get()));

[mmenke, 2014/01/07 19:44:05]

Why are we checking this?

[jkarlin, 2014/01/07 20:10:03]

Done.

[jkarlin, 2014/01/07 20:10:03]

Done.

+}
+
+// Test that network use can be deferred and canceled.
+TEST_P(HttpNetworkTransactionTest, ThrottleAndCancelBeforeNetworkStart) {
+  HttpRequestInfo request;
+  request.method = "GET";
+  request.url = GURL("http://www.google.com/");
+  request.load_flags = 0;
+
+  scoped_refptr<HttpNetworkSession> session(CreateSession(&session_deps_));
+  scoped_ptr<HttpTransaction> trans(
+      new HttpNetworkTransaction(DEFAULT_PRIORITY, session.get()));
+
+  // Defer on OnBeforeNetworkStart.
+  BeforeNetworkStartHandler net_start_handler(true);  // defer
+  trans->SetBeforeNetworkStartCallback(
+      base::Bind(&BeforeNetworkStartHandler::OnBeforeNetworkStart,
+                 base::Unretained(&net_start_handler)));
+
+  MockRead data_reads[] = {MockRead("HTTP/1.0 200 OK\r\n"),
+                           MockRead("Connection: keep-alive\r\n"),
+                           MockRead("Content-Length: 100\r\n\r\n"),
+                           MockRead("hello"),
+                           MockRead(SYNCHRONOUS, 0), };
+  StaticSocketDataProvider data(data_reads, arraysize(data_reads), NULL, 0);
+  session_deps_.socket_factory->AddSocketDataProvider(&data);

[mmenke, 2014/01/07 19:44:05]

We don't need all this.  In fact, it's better not to have it.  That way, if the
test tries to make a socket, things fail, badly.

[jkarlin, 2014/01/07 20:10:03]

Done.

+
+  TestCompletionCallback callback;
+
+  int rv = trans->Start(&request, callback.callback(), BoundNetLog());
+  EXPECT_EQ(ERR_IO_PENDING, rv);
+  base::MessageLoop::current()->RunUntilIdle();
+
+  // Should have deferred for network start.
+  EXPECT_TRUE(net_start_handler.observed_before_network_start());
+  EXPECT_EQ(LOAD_STATE_WAITING_FOR_DELEGATE, trans->GetLoadState());
+  EXPECT_TRUE(trans->GetResponseInfo() == NULL);
+}
+
 // Next 2 cases (KeepAliveEarlyClose and KeepAliveEarlyClose2) are regression
 // tests. There was a bug causing HttpNetworkTransaction to hang in the
 // destructor in such situations.
 // See http://crbug.com/154712 and http://crbug.com/156609.
 TEST_P(HttpNetworkTransactionTest, KeepAliveEarlyClose) {
   HttpRequestInfo request;
   request.method = "GET";
   request.url = GURL("http://www.google.com/");
   request.load_flags = 0;
 
@@ skipping 10977 matching lines @@
   // established, to let the HTTP request start.
   ASSERT_EQ(OK, http_callback.WaitForResult());
   std::string response_data;
   ASSERT_EQ(OK, ReadTransaction(http_trans.get(), &response_data));
   EXPECT_EQ("falafel", response_data);
 
   EXPECT_EQ(1, GetIdleSocketCountInTransportSocketPool(session));
 }
 
 }  // namespace net