Slow start pipelining.

net/http/http_pipelined_connection_impl.cc

Index: net/http/http_pipelined_connection_impl.cc
diff --git a/net/http/http_pipelined_connection_impl.cc b/net/http/http_pipelined_connection_impl.cc
index 82c788f903edbaf88a8861f94bb81e3ea8dcd06d..e4a83925a2241f8a95cf473927f24394ae10a5ed 100644
--- a/net/http/http_pipelined_connection_impl.cc
+++ b/net/http/http_pipelined_connection_impl.cc
@@ -9,7 +9,9 @@
 #include "net/base/io_buffer.h"
 #include "net/http/http_pipelined_stream.h"
 #include "net/http/http_request_info.h"
+#include "net/http/http_response_headers.h"
 #include "net/http/http_stream_parser.h"
+#include "net/http/http_version.h"
 #include "net/socket/client_socket_handle.h"
 
 namespace net {
@@ -165,7 +167,7 @@ int HttpPipelinedConnectionImpl::DoSendRequestLoop(int result) {
         rv = DoEvictPendingSendRequests(rv);
         break;
       default:
-        NOTREACHED() << "bad send state: " << state;
+        CHECK(false) << "bad send state: " << state;
         rv = ERR_FAILED;
         break;
     }
@@ -335,7 +337,7 @@ int HttpPipelinedConnectionImpl::DoReadHeadersLoop(int result) {
       case READ_STATE_NONE:
         break;
       default:
-        NOTREACHED() << "bad read state";
+        CHECK(false) << "bad read state";
         rv = ERR_FAILED;
         break;
     }
@@ -392,7 +394,7 @@ int HttpPipelinedConnectionImpl::DoStartNextDeferredRead(int result) {
       break;
 
     default:
-      NOTREACHED() << "Unexpected read state: "
+      CHECK(false) << "Unexpected read state: "
                    << stream_info_map_[next_id].state;
   }
 
@@ -423,6 +425,8 @@ int HttpPipelinedConnectionImpl::DoReadHeadersComplete(int result) {
     usable_ = false;
   }
 
+  CheckHeadersForPipelineCompatibility(result, active_read_id_);
+
   if (!read_still_on_call_stack_) {
     QueueUserCallback(active_read_id_,
                       stream_info_map_[active_read_id_].read_headers_callback,
@@ -443,6 +447,7 @@ int HttpPipelinedConnectionImpl::DoReadStreamClosed() {
   CHECK_EQ(stream_info_map_[active_read_id_].state, STREAM_CLOSED);
   active_read_id_ = 0;
   if (!usable_) {
+    // TODO(simonjam): Don't wait this long to evict.
     read_next_state_ = READ_STATE_EVICT_PENDING_READS;
     return OK;
   }
@@ -525,7 +530,7 @@ void HttpPipelinedConnectionImpl::Close(int pipeline_id,
       break;
 
     default:
-      NOTREACHED();
+      CHECK(false);
       break;
   }
 }
@@ -606,6 +611,35 @@ void HttpPipelinedConnectionImpl::GetSSLCertRequestInfo(
       cert_request_info);
 }
 
+void HttpPipelinedConnectionImpl::CheckHeadersForPipelineCompatibility(
+    int result,
+    int pipeline_id) {
+  if (result < OK) {

[mmenke, 2011/11/21 14:51:39]

When things go wrong, we won't necessarily get the error, if any, when receiving
headers.  I think we're going to have to play with things in the wild to see if
excluding certain error codes like this works at all.

[James Simonsen, 2011/12/01 01:17:10]

Okay, I've added a TODO. Eventually, I want to circle back and start
instrumenting all of this code so we get some metrics and can start tuning.

+    switch (result) {
+      case ERR_ABORTED:
+      case ERR_INTERNET_DISCONNECTED:
+        // These errors are no fault of the server.
+        break;
+
+      default:
+        delegate_->OnPipelineFeedback(this, SOCKET_ERROR);
+        return;
+    }
+  }
+  HttpResponseInfo* info = GetResponseInfo(pipeline_id);
+  const HttpVersion required_version(1, 1);
+  if (info->headers->GetParsedHttpVersion() < required_version) {
+    delegate_->OnPipelineFeedback(this, OLD_HTTP_VERSION);
+    return;
+  }
+  if (!info->headers->IsKeepAlive() || !CanFindEndOfResponse(pipeline_id)) {
+    usable_ = false;
+    delegate_->OnPipelineFeedback(this, MUST_CLOSE_CONNECTION);
+    return;
+  }

[mmenke, 2011/11/21 14:51:39]

We should also be doing something about NTLM AUTH requests.  Currently, simplest
thing to do is to disallow pipelining and force the connection to close, in that
case.  Feel free to add it as a TODO in this CL.

[James Simonsen, 2011/12/01 01:17:10]

Yeah, that was next on my list. I'm going to do it in a separate CL to directly
address the bug report.

+  delegate_->OnPipelineFeedback(this, OK);
+}
+
 void HttpPipelinedConnectionImpl::QueueUserCallback(
     int pipeline_id,
     OldCompletionCallback* callback,