net/socket/transport_client_socket_pool.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/socket/transport_client_socket_pool.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/compiler_specific.h"
  10 #include "base/lazy_instance.h"
  11 #include "base/logging.h"
  12 #include "base/message_loop/message_loop.h"
  13 #include "base/metrics/histogram.h"
  14 #include "base/profiler/scoped_tracker.h"
  15 #include "base/strings/string_util.h"
  16 #include "base/synchronization/lock.h"
  17 #include "base/time/time.h"
  18 #include "base/values.h"
  19 #include "net/base/ip_endpoint.h"
  20 #include "net/base/net_errors.h"
  21 #include "net/log/net_log.h"
  22 #include "net/socket/client_socket_factory.h"
  23 #include "net/socket/client_socket_handle.h"
  24 #include "net/socket/client_socket_pool_base.h"
  25 #include "net/socket/socket_net_log_params.h"
  26 #include "net/socket/tcp_client_socket.h"
  27
  28 using base::TimeDelta;
  29
  30 namespace net {
  31
  32 // TODO(willchan): Base this off RTT instead of statically setting it. Note we
  33 // choose a timeout that is different from the backup connect job timer so they
  34 // don't synchronize.
  35 const int TransportConnectJobHelper::kIPv6FallbackTimerInMs = 300;
  36
  37 namespace {
  38
  39 // Returns true iff all addresses in |list| are in the IPv6 family.
  40 bool AddressListOnlyContainsIPv6(const AddressList& list) {
  41   DCHECK(!list.empty());
  42   for (AddressList::const_iterator iter = list.begin(); iter != list.end();
  43        ++iter) {
  44     if (iter->GetFamily() != ADDRESS_FAMILY_IPV6)
  45       return false;
  46   }
  47   return true;
  48 }
  49
  50 }  // namespace
  51
  52 // This lock protects |g_last_connect_time|.
  53 static base::LazyInstance<base::Lock>::Leaky
  54     g_last_connect_time_lock = LAZY_INSTANCE_INITIALIZER;
  55
  56 // |g_last_connect_time| has the last time a connect() call is made.
  57 static base::LazyInstance<base::TimeTicks>::Leaky
  58     g_last_connect_time = LAZY_INSTANCE_INITIALIZER;
  59
  60 TransportSocketParams::TransportSocketParams(
  61     const HostPortPair& host_port_pair,
  62     bool disable_resolver_cache,
  63     bool ignore_limits,
  64     const OnHostResolutionCallback& host_resolution_callback,
  65     CombineConnectAndWritePolicy combine_connect_and_write_if_supported)
  66     : destination_(host_port_pair),
  67       ignore_limits_(ignore_limits),
  68       host_resolution_callback_(host_resolution_callback),
  69       combine_connect_and_write_(combine_connect_and_write_if_supported) {
  70   if (disable_resolver_cache)
  71     destination_.set_allow_cached_response(false);
  72   // combine_connect_and_write currently translates to TCP FastOpen.
  73   // Enable TCP FastOpen if user wants it.
  74   if (combine_connect_and_write_ == COMBINE_CONNECT_AND_WRITE_DEFAULT) {
  75     IsTCPFastOpenUserEnabled() ? combine_connect_and_write_ =
  76         COMBINE_CONNECT_AND_WRITE_DESIRED :
  77         COMBINE_CONNECT_AND_WRITE_PROHIBITED;
  78   }
  79 }
  80
  81 TransportSocketParams::~TransportSocketParams() {}
  82
  83 // TransportConnectJobs will time out after this many seconds.  Note this is
  84 // the total time, including both host resolution and TCP connect() times.
  85 //
  86 // TODO(eroman): The use of this constant needs to be re-evaluated. The time
  87 // needed for TCPClientSocketXXX::Connect() can be arbitrarily long, since
  88 // the address list may contain many alternatives, and most of those may
  89 // timeout. Even worse, the per-connect timeout threshold varies greatly
  90 // between systems (anywhere from 20 seconds to 190 seconds).
  91 // See comment #12 at http://crbug.com/23364 for specifics.
  92 static const int kTransportConnectJobTimeoutInSeconds = 240;  // 4 minutes.
  93
  94 TransportConnectJobHelper::TransportConnectJobHelper(
  95     const scoped_refptr<TransportSocketParams>& params,
  96     ClientSocketFactory* client_socket_factory,
  97     HostResolver* host_resolver,
  98     LoadTimingInfo::ConnectTiming* connect_timing)
  99     : params_(params),
 100       client_socket_factory_(client_socket_factory),
 101       resolver_(host_resolver),
 102       next_state_(STATE_NONE),
 103       connect_timing_(connect_timing) {}
 104
 105 TransportConnectJobHelper::~TransportConnectJobHelper() {}
 106
 107 int TransportConnectJobHelper::DoResolveHost(RequestPriority priority,
 108                                              const BoundNetLog& net_log) {
 109   next_state_ = STATE_RESOLVE_HOST_COMPLETE;
 110   connect_timing_->dns_start = base::TimeTicks::Now();
 111
 112   return resolver_.Resolve(
 113       params_->destination(), priority, &addresses_, on_io_complete_, net_log);
 114 }
 115
 116 int TransportConnectJobHelper::DoResolveHostComplete(
 117     int result,
 118     const BoundNetLog& net_log) {
 119   connect_timing_->dns_end = base::TimeTicks::Now();
 120   // Overwrite connection start time, since for connections that do not go
 121   // through proxies, |connect_start| should not include dns lookup time.
 122   connect_timing_->connect_start = connect_timing_->dns_end;
 123
 124   if (result == OK) {
 125     // Invoke callback, and abort if it fails.
 126     if (!params_->host_resolution_callback().is_null())
 127       result = params_->host_resolution_callback().Run(addresses_, net_log);
 128
 129     if (result == OK)
 130       next_state_ = STATE_TRANSPORT_CONNECT;
 131   }
 132   return result;
 133 }
 134
 135 base::TimeDelta TransportConnectJobHelper::HistogramDuration(
 136     ConnectionLatencyHistogram race_result) {
 137   DCHECK(!connect_timing_->connect_start.is_null());
 138   DCHECK(!connect_timing_->dns_start.is_null());
 139   base::TimeTicks now = base::TimeTicks::Now();
 140   base::TimeDelta total_duration = now - connect_timing_->dns_start;
 141   UMA_HISTOGRAM_CUSTOM_TIMES("Net.DNS_Resolution_And_TCP_Connection_Latency2",
 142                              total_duration,
 143                              base::TimeDelta::FromMilliseconds(1),
 144                              base::TimeDelta::FromMinutes(10),
 145                              100);
 146
 147   base::TimeDelta connect_duration = now - connect_timing_->connect_start;
 148   UMA_HISTOGRAM_CUSTOM_TIMES("Net.TCP_Connection_Latency",
 149                              connect_duration,
 150                              base::TimeDelta::FromMilliseconds(1),
 151                              base::TimeDelta::FromMinutes(10),
 152                              100);
 153
 154   switch (race_result) {
 155     case CONNECTION_LATENCY_IPV4_WINS_RACE:
 156       UMA_HISTOGRAM_CUSTOM_TIMES("Net.TCP_Connection_Latency_IPv4_Wins_Race",
 157                                  connect_duration,
 158                                  base::TimeDelta::FromMilliseconds(1),
 159                                  base::TimeDelta::FromMinutes(10),
 160                                  100);
 161       break;
 162
 163     case CONNECTION_LATENCY_IPV4_NO_RACE:
 164       UMA_HISTOGRAM_CUSTOM_TIMES("Net.TCP_Connection_Latency_IPv4_No_Race",
 165                                  connect_duration,
 166                                  base::TimeDelta::FromMilliseconds(1),
 167                                  base::TimeDelta::FromMinutes(10),
 168                                  100);
 169       break;
 170
 171     case CONNECTION_LATENCY_IPV6_RACEABLE:
 172       UMA_HISTOGRAM_CUSTOM_TIMES("Net.TCP_Connection_Latency_IPv6_Raceable",
 173                                  connect_duration,
 174                                  base::TimeDelta::FromMilliseconds(1),
 175                                  base::TimeDelta::FromMinutes(10),
 176                                  100);
 177       break;
 178
 179     case CONNECTION_LATENCY_IPV6_SOLO:
 180       UMA_HISTOGRAM_CUSTOM_TIMES("Net.TCP_Connection_Latency_IPv6_Solo",
 181                                  connect_duration,
 182                                  base::TimeDelta::FromMilliseconds(1),
 183                                  base::TimeDelta::FromMinutes(10),
 184                                  100);
 185       break;
 186
 187     default:
 188       NOTREACHED();
 189       break;
 190   }
 191
 192   return connect_duration;
 193 }
 194
 195 TransportConnectJob::TransportConnectJob(
 196     const std::string& group_name,
 197     RequestPriority priority,
 198     const scoped_refptr<TransportSocketParams>& params,
 199     base::TimeDelta timeout_duration,
 200     ClientSocketFactory* client_socket_factory,
 201     HostResolver* host_resolver,
 202     Delegate* delegate,
 203     NetLog* net_log)
 204     : ConnectJob(group_name, timeout_duration, priority, delegate,
 205                  BoundNetLog::Make(net_log, NetLog::SOURCE_CONNECT_JOB)),
 206       helper_(params, client_socket_factory, host_resolver, &connect_timing_),
 207       interval_between_connects_(CONNECT_INTERVAL_GT_20MS) {
 208   helper_.SetOnIOComplete(this);
 209 }
 210
 211 TransportConnectJob::~TransportConnectJob() {
 212   // We don't worry about cancelling the host resolution and TCP connect, since
 213   // ~SingleRequestHostResolver and ~StreamSocket will take care of it.
 214 }
 215
 216 LoadState TransportConnectJob::GetLoadState() const {
 217   switch (helper_.next_state()) {
 218     case TransportConnectJobHelper::STATE_RESOLVE_HOST:
 219     case TransportConnectJobHelper::STATE_RESOLVE_HOST_COMPLETE:
 220       return LOAD_STATE_RESOLVING_HOST;
 221     case TransportConnectJobHelper::STATE_TRANSPORT_CONNECT:
 222     case TransportConnectJobHelper::STATE_TRANSPORT_CONNECT_COMPLETE:
 223       return LOAD_STATE_CONNECTING;
 224     case TransportConnectJobHelper::STATE_NONE:
 225       return LOAD_STATE_IDLE;
 226   }
 227   NOTREACHED();
 228   return LOAD_STATE_IDLE;
 229 }
 230
 231 // static
 232 void TransportConnectJob::MakeAddressListStartWithIPv4(AddressList* list) {
 233   for (AddressList::iterator i = list->begin(); i != list->end(); ++i) {
 234     if (i->GetFamily() == ADDRESS_FAMILY_IPV4) {
 235       std::rotate(list->begin(), i, list->end());
 236       break;
 237     }
 238   }
 239 }
 240
 241 int TransportConnectJob::DoResolveHost() {
 242   // TODO(ricea): Remove ScopedTracker below once crbug.com/436634 is fixed.
 243   tracked_objects::ScopedTracker tracking_profile(
 244       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 245           "436634 TransportConnectJob::DoResolveHost"));
 246
 247   return helper_.DoResolveHost(priority(), net_log());
 248 }
 249
 250 int TransportConnectJob::DoResolveHostComplete(int result) {
 251   return helper_.DoResolveHostComplete(result, net_log());
 252 }
 253
 254 int TransportConnectJob::DoTransportConnect() {
 255   base::TimeTicks now = base::TimeTicks::Now();
 256   base::TimeTicks last_connect_time;
 257   {
 258     base::AutoLock lock(g_last_connect_time_lock.Get());
 259     last_connect_time = g_last_connect_time.Get();
 260     *g_last_connect_time.Pointer() = now;
 261   }
 262   if (last_connect_time.is_null()) {
 263     interval_between_connects_ = CONNECT_INTERVAL_GT_20MS;
 264   } else {
 265     int64 interval = (now - last_connect_time).InMilliseconds();
 266     if (interval <= 10)
 267       interval_between_connects_ = CONNECT_INTERVAL_LE_10MS;
 268     else if (interval <= 20)
 269       interval_between_connects_ = CONNECT_INTERVAL_LE_20MS;
 270     else
 271       interval_between_connects_ = CONNECT_INTERVAL_GT_20MS;
 272   }
 273
 274   helper_.set_next_state(
 275       TransportConnectJobHelper::STATE_TRANSPORT_CONNECT_COMPLETE);
 276   transport_socket_ =
 277       helper_.client_socket_factory()->CreateTransportClientSocket(
 278           helper_.addresses(), net_log().net_log(), net_log().source());
 279
 280   // If the list contains IPv6 and IPv4 addresses, the first address will
 281   // be IPv6, and the IPv4 addresses will be tried as fallback addresses,
 282   // per "Happy Eyeballs" (RFC 6555).
 283   bool try_ipv6_connect_with_ipv4_fallback =
 284       helper_.addresses().front().GetFamily() == ADDRESS_FAMILY_IPV6 &&
 285       !AddressListOnlyContainsIPv6(helper_.addresses());
 286
 287   // Enable TCP FastOpen if indicated by transport socket params.
 288   // Note: We currently do not turn on TCP FastOpen for destinations where
 289   // we try a TCP connect over IPv6 with fallback to IPv4.
 290   if (!try_ipv6_connect_with_ipv4_fallback &&
 291       helper_.params()->combine_connect_and_write() ==
 292           TransportSocketParams::COMBINE_CONNECT_AND_WRITE_DESIRED) {
 293     transport_socket_->EnableTCPFastOpenIfSupported();
 294   }
 295
 296   int rv = transport_socket_->Connect(helper_.on_io_complete());
 297   if (rv == ERR_IO_PENDING && try_ipv6_connect_with_ipv4_fallback) {
 298     fallback_timer_.Start(
 299         FROM_HERE,
 300         base::TimeDelta::FromMilliseconds(
 301             TransportConnectJobHelper::kIPv6FallbackTimerInMs),
 302         this,
 303         &TransportConnectJob::DoIPv6FallbackTransportConnect);
 304   }
 305   return rv;
 306 }
 307
 308 int TransportConnectJob::DoTransportConnectComplete(int result) {
 309   if (result == OK) {
 310     bool is_ipv4 =
 311         helper_.addresses().front().GetFamily() == ADDRESS_FAMILY_IPV4;
 312     TransportConnectJobHelper::ConnectionLatencyHistogram race_result =
 313         TransportConnectJobHelper::CONNECTION_LATENCY_UNKNOWN;
 314     if (is_ipv4) {
 315       race_result = TransportConnectJobHelper::CONNECTION_LATENCY_IPV4_NO_RACE;
 316     } else {
 317       if (AddressListOnlyContainsIPv6(helper_.addresses())) {
 318         race_result = TransportConnectJobHelper::CONNECTION_LATENCY_IPV6_SOLO;
 319       } else {
 320         race_result =
 321             TransportConnectJobHelper::CONNECTION_LATENCY_IPV6_RACEABLE;
 322       }
 323     }
 324     base::TimeDelta connect_duration = helper_.HistogramDuration(race_result);
 325     switch (interval_between_connects_) {
 326       case CONNECT_INTERVAL_LE_10MS:
 327         UMA_HISTOGRAM_CUSTOM_TIMES(
 328             "Net.TCP_Connection_Latency_Interval_LessThanOrEqual_10ms",
 329             connect_duration,
 330             base::TimeDelta::FromMilliseconds(1),
 331             base::TimeDelta::FromMinutes(10),
 332             100);
 333         break;
 334       case CONNECT_INTERVAL_LE_20MS:
 335         UMA_HISTOGRAM_CUSTOM_TIMES(
 336             "Net.TCP_Connection_Latency_Interval_LessThanOrEqual_20ms",
 337             connect_duration,
 338             base::TimeDelta::FromMilliseconds(1),
 339             base::TimeDelta::FromMinutes(10),
 340             100);
 341         break;
 342       case CONNECT_INTERVAL_GT_20MS:
 343         UMA_HISTOGRAM_CUSTOM_TIMES(
 344             "Net.TCP_Connection_Latency_Interval_GreaterThan_20ms",
 345             connect_duration,
 346             base::TimeDelta::FromMilliseconds(1),
 347             base::TimeDelta::FromMinutes(10),
 348             100);
 349         break;
 350       default:
 351         NOTREACHED();
 352         break;
 353     }
 354
 355     SetSocket(transport_socket_.Pass());
 356     fallback_timer_.Stop();
 357   } else {
 358     // Be a bit paranoid and kill off the fallback members to prevent reuse.
 359     fallback_transport_socket_.reset();
 360     fallback_addresses_.reset();
 361   }
 362
 363   return result;
 364 }
 365
 366 void TransportConnectJob::DoIPv6FallbackTransportConnect() {
 367   // The timer should only fire while we're waiting for the main connect to
 368   // succeed.
 369   if (helper_.next_state() !=
 370       TransportConnectJobHelper::STATE_TRANSPORT_CONNECT_COMPLETE) {
 371     NOTREACHED();
 372     return;
 373   }
 374
 375   DCHECK(!fallback_transport_socket_.get());
 376   DCHECK(!fallback_addresses_.get());
 377
 378   fallback_addresses_.reset(new AddressList(helper_.addresses()));
 379   MakeAddressListStartWithIPv4(fallback_addresses_.get());
 380   fallback_transport_socket_ =
 381       helper_.client_socket_factory()->CreateTransportClientSocket(
 382           *fallback_addresses_, net_log().net_log(), net_log().source());
 383   fallback_connect_start_time_ = base::TimeTicks::Now();
 384   int rv = fallback_transport_socket_->Connect(
 385       base::Bind(
 386           &TransportConnectJob::DoIPv6FallbackTransportConnectComplete,
 387           base::Unretained(this)));
 388   if (rv != ERR_IO_PENDING)
 389     DoIPv6FallbackTransportConnectComplete(rv);
 390 }
 391
 392 void TransportConnectJob::DoIPv6FallbackTransportConnectComplete(int result) {
 393   // This should only happen when we're waiting for the main connect to succeed.
 394   if (helper_.next_state() !=
 395       TransportConnectJobHelper::STATE_TRANSPORT_CONNECT_COMPLETE) {
 396     NOTREACHED();
 397     return;
 398   }
 399
 400   DCHECK_NE(ERR_IO_PENDING, result);
 401   DCHECK(fallback_transport_socket_.get());
 402   DCHECK(fallback_addresses_.get());
 403
 404   if (result == OK) {
 405     DCHECK(!fallback_connect_start_time_.is_null());
 406     connect_timing_.connect_start = fallback_connect_start_time_;
 407     helper_.HistogramDuration(
 408         TransportConnectJobHelper::CONNECTION_LATENCY_IPV4_WINS_RACE);
 409     SetSocket(fallback_transport_socket_.Pass());
 410     helper_.set_next_state(TransportConnectJobHelper::STATE_NONE);
 411     transport_socket_.reset();
 412   } else {
 413     // Be a bit paranoid and kill off the fallback members to prevent reuse.
 414     fallback_transport_socket_.reset();
 415     fallback_addresses_.reset();
 416   }
 417   NotifyDelegateOfCompletion(result);  // Deletes |this|
 418 }
 419
 420 int TransportConnectJob::ConnectInternal() {
 421   return helper_.DoConnectInternal(this);
 422 }
 423
 424 scoped_ptr<ConnectJob>
 425 TransportClientSocketPool::TransportConnectJobFactory::NewConnectJob(
 426     const std::string& group_name,
 427     const PoolBase::Request& request,
 428     ConnectJob::Delegate* delegate) const {
 429   return scoped_ptr<ConnectJob>(
 430       new TransportConnectJob(group_name,
 431                               request.priority(),
 432                               request.params(),
 433                               ConnectionTimeout(),
 434                               client_socket_factory_,
 435                               host_resolver_,
 436                               delegate,
 437                               net_log_));
 438 }
 439
 440 base::TimeDelta
 441     TransportClientSocketPool::TransportConnectJobFactory::ConnectionTimeout()
 442     const {
 443   return base::TimeDelta::FromSeconds(kTransportConnectJobTimeoutInSeconds);
 444 }
 445
 446 TransportClientSocketPool::TransportClientSocketPool(
 447     int max_sockets,
 448     int max_sockets_per_group,
 449     HostResolver* host_resolver,
 450     ClientSocketFactory* client_socket_factory,
 451     NetLog* net_log)
 452     : base_(NULL,
 453             max_sockets,
 454             max_sockets_per_group,
 455             ClientSocketPool::unused_idle_socket_timeout(),
 456             ClientSocketPool::used_idle_socket_timeout(),
 457             new TransportConnectJobFactory(client_socket_factory,
 458                                            host_resolver,
 459                                            net_log)) {
 460   base_.EnableConnectBackupJobs();
 461 }
 462
 463 TransportClientSocketPool::~TransportClientSocketPool() {}
 464
 465 int TransportClientSocketPool::RequestSocket(
 466     const std::string& group_name,
 467     const void* params,
 468     RequestPriority priority,
 469     ClientSocketHandle* handle,
 470     const CompletionCallback& callback,
 471     const BoundNetLog& net_log) {
 472   const scoped_refptr<TransportSocketParams>* casted_params =
 473       static_cast<const scoped_refptr<TransportSocketParams>*>(params);
 474
 475   NetLogTcpClientSocketPoolRequestedSocket(net_log, casted_params);
 476
 477   return base_.RequestSocket(group_name, *casted_params, priority, handle,
 478                              callback, net_log);
 479 }
 480
 481 void TransportClientSocketPool::NetLogTcpClientSocketPoolRequestedSocket(
 482     const BoundNetLog& net_log,
 483     const scoped_refptr<TransportSocketParams>* casted_params) {
 484   if (net_log.GetCaptureMode().enabled()) {
 485     // TODO(eroman): Split out the host and port parameters.
 486     net_log.AddEvent(
 487         NetLog::TYPE_TCP_CLIENT_SOCKET_POOL_REQUESTED_SOCKET,
 488         CreateNetLogHostPortPairCallback(
 489             &casted_params->get()->destination().host_port_pair()));
 490   }
 491 }
 492
 493 void TransportClientSocketPool::RequestSockets(
 494     const std::string& group_name,
 495     const void* params,
 496     int num_sockets,
 497     const BoundNetLog& net_log) {
 498   const scoped_refptr<TransportSocketParams>* casted_params =
 499       static_cast<const scoped_refptr<TransportSocketParams>*>(params);
 500
 501   if (net_log.GetCaptureMode().enabled()) {
 502     // TODO(eroman): Split out the host and port parameters.
 503     net_log.AddEvent(
 504         NetLog::TYPE_TCP_CLIENT_SOCKET_POOL_REQUESTED_SOCKETS,
 505         CreateNetLogHostPortPairCallback(
 506             &casted_params->get()->destination().host_port_pair()));
 507   }
 508
 509   base_.RequestSockets(group_name, *casted_params, num_sockets, net_log);
 510 }
 511
 512 void TransportClientSocketPool::CancelRequest(
 513     const std::string& group_name,
 514     ClientSocketHandle* handle) {
 515   base_.CancelRequest(group_name, handle);
 516 }
 517
 518 void TransportClientSocketPool::ReleaseSocket(
 519     const std::string& group_name,
 520     scoped_ptr<StreamSocket> socket,
 521     int id) {
 522   base_.ReleaseSocket(group_name, socket.Pass(), id);
 523 }
 524
 525 void TransportClientSocketPool::FlushWithError(int error) {
 526   base_.FlushWithError(error);
 527 }
 528
 529 void TransportClientSocketPool::CloseIdleSockets() {
 530   base_.CloseIdleSockets();
 531 }
 532
 533 int TransportClientSocketPool::IdleSocketCount() const {
 534   return base_.idle_socket_count();
 535 }
 536
 537 int TransportClientSocketPool::IdleSocketCountInGroup(
 538     const std::string& group_name) const {
 539   return base_.IdleSocketCountInGroup(group_name);
 540 }
 541
 542 LoadState TransportClientSocketPool::GetLoadState(
 543     const std::string& group_name, const ClientSocketHandle* handle) const {
 544   return base_.GetLoadState(group_name, handle);
 545 }
 546
 547 base::DictionaryValue* TransportClientSocketPool::GetInfoAsValue(
 548     const std::string& name,
 549     const std::string& type,
 550     bool include_nested_pools) const {
 551   return base_.GetInfoAsValue(name, type);
 552 }
 553
 554 base::TimeDelta TransportClientSocketPool::ConnectionTimeout() const {
 555   return base_.ConnectionTimeout();
 556 }
 557
 558 bool TransportClientSocketPool::IsStalled() const {
 559   return base_.IsStalled();
 560 }
 561
 562 void TransportClientSocketPool::AddHigherLayeredPool(
 563     HigherLayeredPool* higher_pool) {
 564   base_.AddHigherLayeredPool(higher_pool);
 565 }
 566
 567 void TransportClientSocketPool::RemoveHigherLayeredPool(
 568     HigherLayeredPool* higher_pool) {
 569   base_.RemoveHigherLayeredPool(higher_pool);
 570 }
 571
 572 }  // namespace net