Deciding best connection to schedule requests on based on cwnd and idle time

net/http/http_basic_stream.cc

Index: net/http/http_basic_stream.cc
===================================================================
--- net/http/http_basic_stream.cc	(revision 86260)
+++ net/http/http_basic_stream.cc	(working copy)
@@ -4,6 +4,7 @@
 
 #include "net/http/http_basic_stream.h"
 
+#include "base/metrics/histogram.h"
 #include "base/stringprintf.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ -34,6 +35,7 @@
   request_info_ = request_info;
   parser_.reset(new HttpStreamParser(connection_.get(), request_info,
                                      read_buf_, net_log));
+  bytes_read_offset_ = connection_->socket()->NumBytesRead();
   return OK;
 }
 
@@ -50,6 +52,7 @@
   request_line_ = base::StringPrintf("%s %s HTTP/1.1\r\n",
                                      request_info_->method.c_str(),
                                      path.c_str());
+  response_ = response;
   return parser_->SendRequest(request_line_, headers, request_body, response,
                               callback);
 }
@@ -119,4 +122,23 @@
   return false;
 }
 
+void HttpBasicStream::LogRttVsBytesMetrics() const {
+  int bytes_received = connection_->socket()->NumBytesRead() -
+                       bytes_read_offset_;
+  int num_kb = bytes_received / 1024;
+  double rtt = connection_->socket()->GetRTTInMs();
+
+  if (num_kb < 1024 && rtt > 0) {  // Ignore responses > 1MB
+    base::TimeDelta duration = base::Time::Now() -
+                               response_->request_time;
+    double num_rtt = static_cast<double>(duration.InMilliseconds()) / rtt;
+    int num_rtt_scaled = (4 * num_rtt);
+    int val = 1024 * num_rtt_scaled + num_kb;  // Supports ~500 RTT of 1418 B.
+    HISTOGRAM_CUSTOM_COUNTS("Net.RTT_vs_KB", val, 4096, 3048000, 1000);
+    LOG(ERROR) << request_line_
+               << "\nrtt = " << rtt << "\tnum_rtt = " << num_rtt
+               << "\tnum_kb = " << num_kb << "\tval = " << val;
+  }
+}
+
 }  // namespace net