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

chrome/browser/browser_main.cc

Index: chrome/browser/browser_main.cc
===================================================================
--- chrome/browser/browser_main.cc	(revision 88789)
+++ chrome/browser/browser_main.cc	(working copy)
@@ -100,6 +100,7 @@
 #include "net/base/cookie_monster.h"
 #include "net/base/net_module.h"
 #include "net/base/network_change_notifier.h"
+#include "net/http/http_basic_stream.h"
 #include "net/http/http_network_layer.h"
 #include "net/http/http_stream_factory.h"
 #include "net/socket/client_socket_pool_base.h"
@@ -207,6 +208,9 @@
 #include "views/touchui/touch_factory.h"
 #endif
 
+using net::internal::ClientSocketPoolBaseHelper;

[willchan no longer on Chromium, 2011/06/13 15:06:07]

internal is a net/ internal implementation detail. It should not be accessed
from outside of net/. It looks like we regressed on this before. Please don't
add another regression. Probably what you should do is make these functions be
free functions in the net namespace, although it can be in the
client_socket_pool_base.h header file. They should then set file local variables
in client_socket_pool_base.cc.

And I don't think there are enough use cases here to justify using a using
declaration. Use the fully qualified names please.

[Gagan, 2011/06/13 16:45:58]

Done.

+using net::HttpBasicStream;
+
 namespace net {
 class NetLog;
 }  // namespace net
@@ -474,6 +478,61 @@
   }
 }
 
+// If --socket-reuse-policy is not specified, run an A/B test for choosing the
+// warmest socket.
+void BrowserMainParts::WarmConnectionFieldTrial() {
+  const CommandLine& command_line = parsed_command_line();
+  if (command_line.HasSwitch(switches::kSocketReusePolicy)) {
+    std::string alpha_str = command_line.GetSwitchValueASCII(
+        switches::kSocketReusePolicy);
+    int coef = -1;
+    base::StringToInt(alpha_str, &coef);
+
+    const int socket_policy[] = { 0, 1, 2 };
+    LOG(ERROR) << "Chose socket_reuse_policy coef = " << coef;

[willchan no longer on Chromium, 2011/06/13 15:06:07]

Remove this.

[Gagan, 2011/06/14 18:25:02]

Convered to DLOG(INFO)

+    ApplySocketReuseGroup(coef, socket_policy, arraysize(socket_policy));

[willchan no longer on Chromium, 2011/06/13 15:06:07]

I have no idea what "coef" means. You call this with
"warmest_socket_trial_group" below. I don't see the connection between "coef"
and "warmest_socket_trial_group". Please refactor/rename your code so it makes
sense.

[Gagan, 2011/06/13 16:45:58]

Done.

+    return;
+  }
+
+  const base::FieldTrial::Probability kWarmSocketDivisor = 100;
+  const base::FieldTrial::Probability kWarmSocketProbability = 33;
+
+  // After January 30, 2013 builds, it will always be in default group.
+  scoped_refptr<base::FieldTrial> warmest_socket_trial(
+      new base::FieldTrial(
+          "WarmSocketImpact", kWarmSocketDivisor, "last_accessed_socket",
+          2013, 1, 30));
+
+  // Default value is USE_LAST_ACCESSED_SOCKET.
+  const int last_accessed_socket = warmest_socket_trial->kDefaultGroupNumber;
+  const int warmest_socket = warmest_socket_trial->AppendGroup(
+      "warmest_socket", kWarmSocketProbability);
+  const int warm_socket = warmest_socket_trial->AppendGroup(
+      "warm_socket", kWarmSocketProbability);
+
+  const int warmest_socket_trial_group = warmest_socket_trial->group();
+
+  const int socket_policy[] = { warmest_socket, warm_socket,
+                                last_accessed_socket };
+  ApplySocketReuseGroup(warmest_socket_trial_group, socket_policy,
+                        arraysize(socket_policy));
+}
+
+void BrowserMainParts::ApplySocketReuseGroup(int warmest_socket_trial_group,

[willchan no longer on Chromium, 2011/06/13 15:06:07]

Please move this into an anonymous namespace rather than making it a member
function.

[Gagan, 2011/06/13 16:45:58]

Done.

+                                             const int socket_policy[],
+                                             int num_groups) {
+  for (int i = 0; i < num_groups; i++) {
+    if (warmest_socket_trial_group == socket_policy[i]) {
+      ClientSocketPoolBaseHelper::SetSocketReusePolicy(i);
+      HttpBasicStream::SetSocketReusePolicy(i);
+      return;
+    }
+  }
+
+  LOG(ERROR) << "Not a valid socket reuse policy group";

[willchan no longer on Chromium, 2011/06/13 15:06:07]

This is redundant, just use the NOTREACHED.

[Gagan, 2011/06/14 18:25:02]

Done.

+  NOTREACHED() << "Not a valid socket reuse policy group";
+}
+
 // If neither --enable-connect-backup-jobs or --disable-connect-backup-jobs is
 // specified, run an A/B test for automatically establishing backup TCP
 // connections when a certain timeout value is exceeded.
@@ -611,6 +670,7 @@
   SpdyFieldTrial();
   ConnectBackupJobsFieldTrial();
   RevocationCheckingDisabledFieldTrial();
+  WarmConnectionFieldTrial();
 }
 
 // -----------------------------------------------------------------------------