src/google_apis/gcm/engine/mcs_client.cc

   1 // Copyright 2013 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 "google_apis/gcm/engine/mcs_client.h"
   6
   7 #include <set>
   8
   9 #include "base/basictypes.h"
  10 #include "base/bind.h"
  11 #include "base/message_loop/message_loop.h"
  12 #include "base/metrics/histogram.h"
  13 #include "base/strings/string_number_conversions.h"
  14 #include "base/time/clock.h"
  15 #include "base/time/time.h"
  16 #include "base/timer/timer.h"
  17 #include "google_apis/gcm/base/mcs_util.h"
  18 #include "google_apis/gcm/base/socket_stream.h"
  19 #include "google_apis/gcm/engine/connection_factory.h"
  20 #include "google_apis/gcm/monitoring/gcm_stats_recorder.h"
  21
  22 using namespace google::protobuf::io;
  23
  24 namespace gcm {
  25
  26 namespace {
  27
  28 typedef scoped_ptr<google::protobuf::MessageLite> MCSProto;
  29
  30 // The category of messages intended for the GCM client itself from MCS.
  31 const char kMCSCategory[] = "com.google.android.gsf.gtalkservice";
  32
  33 // The from field for messages originating in the GCM client.
  34 const char kGCMFromField[] = "gcm@android.com";
  35
  36 // MCS status message types.
  37 // TODO(zea): handle these at the GCMClient layer.
  38 const char kIdleNotification[] = "IdleNotification";
  39 // const char kAlwaysShowOnIdle[] = "ShowAwayOnIdle";
  40 // const char kPowerNotification[] = "PowerNotification";
  41 // const char kDataActiveNotification[] = "DataActiveNotification";
  42
  43 // The number of unacked messages to allow before sending a stream ack.
  44 // Applies to both incoming and outgoing messages.
  45 // TODO(zea): make this server configurable.
  46 const int kUnackedMessageBeforeStreamAck = 10;
  47
  48 // The global maximum number of pending messages to have in the send queue.
  49 const size_t kMaxSendQueueSize = 10 * 1024;
  50
  51 // The maximum message size that can be sent to the server.
  52 const int kMaxMessageBytes = 4 * 1024;  // 4KB, like the server.
  53
  54 // Helper for converting a proto persistent id list to a vector of strings.
  55 bool BuildPersistentIdListFromProto(const google::protobuf::string& bytes,
  56                                     std::vector<std::string>* id_list) {
  57   mcs_proto::SelectiveAck selective_ack;
  58   if (!selective_ack.ParseFromString(bytes))
  59     return false;
  60   std::vector<std::string> new_list;
  61   for (int i = 0; i < selective_ack.id_size(); ++i) {
  62     DCHECK(!selective_ack.id(i).empty());
  63     new_list.push_back(selective_ack.id(i));
  64   }
  65   id_list->swap(new_list);
  66   return true;
  67 }
  68
  69 }  // namespace
  70
  71 class CollapseKey {
  72  public:
  73   explicit CollapseKey(const mcs_proto::DataMessageStanza& message);
  74   ~CollapseKey();
  75
  76   // Comparison operator for use in maps.
  77   bool operator<(const CollapseKey& right) const;
  78
  79   // Whether the message had a valid collapse key.
  80   bool IsValid() const;
  81
  82   std::string token() const { return token_; }
  83   std::string app_id() const { return app_id_; }
  84   int64 device_user_id() const { return device_user_id_; }
  85
  86  private:
  87   const std::string token_;
  88   const std::string app_id_;
  89   const int64 device_user_id_;
  90 };
  91
  92 CollapseKey::CollapseKey(const mcs_proto::DataMessageStanza& message)
  93     : token_(message.token()),
  94       app_id_(message.category()),
  95       device_user_id_(message.device_user_id()) {}
  96
  97 CollapseKey::~CollapseKey() {}
  98
  99 bool CollapseKey::IsValid() const {
 100   // Device user id is optional, but the application id and token are not.
 101   return !token_.empty() && !app_id_.empty();
 102 }
 103
 104 bool CollapseKey::operator<(const CollapseKey& right) const {
 105   if (device_user_id_ != right.device_user_id())
 106     return device_user_id_ < right.device_user_id();
 107   if (app_id_ != right.app_id())
 108     return app_id_ < right.app_id();
 109   return token_ < right.token();
 110 }
 111
 112 struct ReliablePacketInfo {
 113   ReliablePacketInfo();
 114   ~ReliablePacketInfo();
 115
 116   // The stream id with which the message was sent.
 117   uint32 stream_id;
 118
 119   // If reliable delivery was requested, the persistent id of the message.
 120   std::string persistent_id;
 121
 122   // The type of message itself (for easier lookup).
 123   uint8 tag;
 124
 125   // The protobuf of the message itself.
 126   MCSProto protobuf;
 127 };
 128
 129 ReliablePacketInfo::ReliablePacketInfo()
 130   : stream_id(0), tag(0) {
 131 }
 132 ReliablePacketInfo::~ReliablePacketInfo() {}
 133
 134 int MCSClient::GetSendQueueSize() const {
 135   return to_send_.size();
 136 }
 137
 138 int MCSClient::GetResendQueueSize() const {
 139   return to_resend_.size();
 140 }
 141
 142 std::string MCSClient::GetStateString() const {
 143   switch(state_) {
 144     case UNINITIALIZED:
 145       return "UNINITIALIZED";
 146     case LOADED:
 147       return "LOADED";
 148     case CONNECTING:
 149       return "CONNECTING";
 150     case CONNECTED:
 151       return "CONNECTED";
 152     default:
 153       NOTREACHED();
 154       return std::string();
 155   }
 156 }
 157
 158 MCSClient::MCSClient(const std::string& version_string,
 159                      base::Clock* clock,
 160                      ConnectionFactory* connection_factory,
 161                      GCMStore* gcm_store,
 162                      GCMStatsRecorder* recorder,
 163                      scoped_ptr<base::Timer> heartbeat_timer)
 164     : version_string_(version_string),
 165       clock_(clock),
 166       state_(UNINITIALIZED),
 167       android_id_(0),
 168       security_token_(0),
 169       connection_factory_(connection_factory),
 170       connection_handler_(NULL),
 171       last_device_to_server_stream_id_received_(0),
 172       last_server_to_device_stream_id_received_(0),
 173       stream_id_out_(0),
 174       stream_id_in_(0),
 175       gcm_store_(gcm_store),
 176       heartbeat_manager_(heartbeat_timer.Pass()),
 177       recorder_(recorder),
 178       weak_ptr_factory_(this) {
 179 }
 180
 181 MCSClient::~MCSClient() {
 182 }
 183
 184 void MCSClient::Initialize(
 185     const ErrorCallback& error_callback,
 186     const OnMessageReceivedCallback& message_received_callback,
 187     const OnMessageSentCallback& message_sent_callback,
 188     scoped_ptr<GCMStore::LoadResult> load_result) {
 189   DCHECK_EQ(state_, UNINITIALIZED);
 190
 191   state_ = LOADED;
 192   mcs_error_callback_ = error_callback;
 193   message_received_callback_ = message_received_callback;
 194   message_sent_callback_ = message_sent_callback;
 195
 196   connection_factory_->Initialize(
 197       base::Bind(&MCSClient::ResetStateAndBuildLoginRequest,
 198                  weak_ptr_factory_.GetWeakPtr()),
 199       base::Bind(&MCSClient::HandlePacketFromWire,
 200                  weak_ptr_factory_.GetWeakPtr()),
 201       base::Bind(&MCSClient::MaybeSendMessage,
 202                  weak_ptr_factory_.GetWeakPtr()));
 203   connection_handler_ = connection_factory_->GetConnectionHandler();
 204
 205   stream_id_out_ = 1;  // Login request is hardcoded to id 1.
 206
 207   android_id_ = load_result->device_android_id;
 208   security_token_ = load_result->device_security_token;
 209
 210   if (android_id_ == 0) {
 211     DVLOG(1) << "No device credentials found, assuming new client.";
 212     // No need to try and load RMQ data in that case.
 213     return;
 214   }
 215
 216   // |android_id_| is non-zero, so should |security_token_|.
 217   DCHECK_NE(0u, security_token_) << "Security token invalid, while android id"
 218                                  << " is non-zero.";
 219
 220   DVLOG(1) << "RMQ Load finished with " << load_result->incoming_messages.size()
 221            << " incoming acks pending and "
 222            << load_result->outgoing_messages.size()
 223            << " outgoing messages pending.";
 224
 225   restored_unackeds_server_ids_ = load_result->incoming_messages;
 226
 227   // First go through and order the outgoing messages by recency.
 228   std::map<uint64, google::protobuf::MessageLite*> ordered_messages;
 229   std::vector<PersistentId> expired_ttl_ids;
 230   for (GCMStore::OutgoingMessageMap::iterator iter =
 231            load_result->outgoing_messages.begin();
 232        iter != load_result->outgoing_messages.end(); ++iter) {
 233     uint64 timestamp = 0;
 234     if (!base::StringToUint64(iter->first, &timestamp)) {
 235       LOG(ERROR) << "Invalid restored message.";
 236       // TODO(fgorski): Error: data unreadable
 237       mcs_error_callback_.Run();
 238       return;
 239     }
 240
 241     // Check if the TTL has expired for this message.
 242     if (HasTTLExpired(*iter->second, clock_)) {
 243       expired_ttl_ids.push_back(iter->first);
 244       NotifyMessageSendStatus(*iter->second, TTL_EXCEEDED);
 245       continue;
 246     }
 247
 248     ordered_messages[timestamp] = iter->second.release();
 249   }
 250
 251   if (!expired_ttl_ids.empty()) {
 252     gcm_store_->RemoveOutgoingMessages(
 253         expired_ttl_ids,
 254         base::Bind(&MCSClient::OnGCMUpdateFinished,
 255                    weak_ptr_factory_.GetWeakPtr()));
 256   }
 257
 258   // Now go through and add the outgoing messages to the send queue in their
 259   // appropriate order (oldest at front, most recent at back).
 260   for (std::map<uint64, google::protobuf::MessageLite*>::iterator
 261            iter = ordered_messages.begin();
 262        iter != ordered_messages.end(); ++iter) {
 263     ReliablePacketInfo* packet_info = new ReliablePacketInfo();
 264     packet_info->protobuf.reset(iter->second);
 265     packet_info->tag = GetMCSProtoTag(*iter->second);
 266     packet_info->persistent_id = base::Uint64ToString(iter->first);
 267     to_send_.push_back(make_linked_ptr(packet_info));
 268
 269     if (packet_info->tag == kDataMessageStanzaTag) {
 270       mcs_proto::DataMessageStanza* data_message =
 271           reinterpret_cast<mcs_proto::DataMessageStanza*>(
 272               packet_info->protobuf.get());
 273       CollapseKey collapse_key(*data_message);
 274       if (collapse_key.IsValid())
 275         collapse_key_map_[collapse_key] = packet_info;
 276     }
 277   }
 278 }
 279
 280 void MCSClient::Login(uint64 android_id, uint64 security_token) {
 281   DCHECK_EQ(state_, LOADED);
 282   DCHECK(android_id_ == 0 || android_id_ == android_id);
 283   DCHECK(security_token_ == 0 || security_token_ == security_token);
 284
 285   if (android_id != android_id_ && security_token != security_token_) {
 286     DCHECK(android_id);
 287     DCHECK(security_token);
 288     android_id_ = android_id;
 289     security_token_ = security_token;
 290   }
 291
 292   DCHECK(android_id_ != 0 || restored_unackeds_server_ids_.empty());
 293
 294   state_ = CONNECTING;
 295   connection_factory_->Connect();
 296 }
 297
 298 void MCSClient::SendMessage(const MCSMessage& message) {
 299   int ttl = GetTTL(message.GetProtobuf());
 300   DCHECK_GE(ttl, 0);
 301   if (to_send_.size() > kMaxSendQueueSize) {
 302     NotifyMessageSendStatus(message.GetProtobuf(), QUEUE_SIZE_LIMIT_REACHED);
 303     return;
 304   }
 305   if (message.size() > kMaxMessageBytes) {
 306     NotifyMessageSendStatus(message.GetProtobuf(), MESSAGE_TOO_LARGE);
 307     return;
 308   }
 309
 310   scoped_ptr<ReliablePacketInfo> packet_info(new ReliablePacketInfo());
 311   packet_info->tag = message.tag();
 312   packet_info->protobuf = message.CloneProtobuf();
 313
 314   if (ttl > 0) {
 315     DCHECK_EQ(message.tag(), kDataMessageStanzaTag);
 316
 317     // First check if this message should replace a pending message with the
 318     // same collapse key.
 319     mcs_proto::DataMessageStanza* data_message =
 320         reinterpret_cast<mcs_proto::DataMessageStanza*>(
 321             packet_info->protobuf.get());
 322     CollapseKey collapse_key(*data_message);
 323     if (collapse_key.IsValid() && collapse_key_map_.count(collapse_key) > 0) {
 324       ReliablePacketInfo* original_packet = collapse_key_map_[collapse_key];
 325       DVLOG(1) << "Found matching collapse key, Reusing persistent id of "
 326                << original_packet->persistent_id;
 327       original_packet->protobuf = packet_info->protobuf.Pass();
 328       SetPersistentId(original_packet->persistent_id,
 329                       original_packet->protobuf.get());
 330       gcm_store_->OverwriteOutgoingMessage(
 331           original_packet->persistent_id,
 332           message,
 333           base::Bind(&MCSClient::OnGCMUpdateFinished,
 334                      weak_ptr_factory_.GetWeakPtr()));
 335
 336       // The message is already queued, return.
 337       return;
 338     } else {
 339       PersistentId persistent_id = GetNextPersistentId();
 340       DVLOG(1) << "Setting persistent id to " << persistent_id;
 341       packet_info->persistent_id = persistent_id;
 342       SetPersistentId(persistent_id, packet_info->protobuf.get());
 343       if (!gcm_store_->AddOutgoingMessage(
 344                persistent_id,
 345                MCSMessage(message.tag(), *(packet_info->protobuf)),
 346                base::Bind(&MCSClient::OnGCMUpdateFinished,
 347                           weak_ptr_factory_.GetWeakPtr()))) {
 348         NotifyMessageSendStatus(message.GetProtobuf(),
 349                                 APP_QUEUE_SIZE_LIMIT_REACHED);
 350         return;
 351       }
 352     }
 353
 354     if (collapse_key.IsValid())
 355       collapse_key_map_[collapse_key] = packet_info.get();
 356   } else if (!connection_factory_->IsEndpointReachable()) {
 357     DVLOG(1) << "No active connection, dropping message.";
 358     NotifyMessageSendStatus(message.GetProtobuf(), NO_CONNECTION_ON_ZERO_TTL);
 359     return;
 360   }
 361
 362   to_send_.push_back(make_linked_ptr(packet_info.release()));
 363
 364   // Notify that the messages has been succsfully queued for sending.
 365   // TODO(jianli): We should report QUEUED after writing to GCM store succeeds.
 366   NotifyMessageSendStatus(message.GetProtobuf(), QUEUED);
 367
 368   MaybeSendMessage();
 369 }
 370
 371 void MCSClient::ResetStateAndBuildLoginRequest(
 372     mcs_proto::LoginRequest* request) {
 373   DCHECK(android_id_);
 374   DCHECK(security_token_);
 375   stream_id_in_ = 0;
 376   stream_id_out_ = 1;
 377   last_device_to_server_stream_id_received_ = 0;
 378   last_server_to_device_stream_id_received_ = 0;
 379
 380   heartbeat_manager_.Stop();
 381
 382   // Add any pending acknowledgments to the list of ids.
 383   for (StreamIdToPersistentIdMap::const_iterator iter =
 384            unacked_server_ids_.begin();
 385        iter != unacked_server_ids_.end(); ++iter) {
 386     restored_unackeds_server_ids_.push_back(iter->second);
 387   }
 388   unacked_server_ids_.clear();
 389
 390   // Any acknowledged server ids which have not been confirmed by the server
 391   // are treated like unacknowledged ids.
 392   for (std::map<StreamId, PersistentIdList>::const_iterator iter =
 393            acked_server_ids_.begin();
 394        iter != acked_server_ids_.end(); ++iter) {
 395     restored_unackeds_server_ids_.insert(restored_unackeds_server_ids_.end(),
 396                                          iter->second.begin(),
 397                                          iter->second.end());
 398   }
 399   acked_server_ids_.clear();
 400
 401   // Then build the request, consuming all pending acknowledgments.
 402   request->Swap(BuildLoginRequest(android_id_,
 403                                   security_token_,
 404                                   version_string_).get());
 405   for (PersistentIdList::const_iterator iter =
 406            restored_unackeds_server_ids_.begin();
 407        iter != restored_unackeds_server_ids_.end(); ++iter) {
 408     request->add_received_persistent_id(*iter);
 409   }
 410   acked_server_ids_[stream_id_out_] = restored_unackeds_server_ids_;
 411   restored_unackeds_server_ids_.clear();
 412
 413   // Push all unacknowledged messages to front of send queue. No need to save
 414   // to RMQ, as all messages that reach this point should already have been
 415   // saved as necessary.
 416   while (!to_resend_.empty()) {
 417     to_send_.push_front(to_resend_.back());
 418     to_resend_.pop_back();
 419   }
 420
 421   // Drop all TTL == 0 or expired TTL messages from the queue.
 422   std::deque<MCSPacketInternal> new_to_send;
 423   std::vector<PersistentId> expired_ttl_ids;
 424   while (!to_send_.empty()) {
 425     MCSPacketInternal packet = PopMessageForSend();
 426     if (GetTTL(*packet->protobuf) > 0 &&
 427         !HasTTLExpired(*packet->protobuf, clock_)) {
 428       new_to_send.push_back(packet);
 429     } else {
 430       // If the TTL was 0 there is no persistent id, so no need to remove the
 431       // message from the persistent store.
 432       if (!packet->persistent_id.empty())
 433         expired_ttl_ids.push_back(packet->persistent_id);
 434       NotifyMessageSendStatus(*packet->protobuf, TTL_EXCEEDED);
 435     }
 436   }
 437
 438   if (!expired_ttl_ids.empty()) {
 439     DVLOG(1) << "Connection reset, " << expired_ttl_ids.size()
 440              << " messages expired.";
 441     gcm_store_->RemoveOutgoingMessages(
 442         expired_ttl_ids,
 443         base::Bind(&MCSClient::OnGCMUpdateFinished,
 444                    weak_ptr_factory_.GetWeakPtr()));
 445   }
 446
 447   to_send_.swap(new_to_send);
 448
 449   DVLOG(1) << "Resetting state, with " << request->received_persistent_id_size()
 450            << " incoming acks pending, and " << to_send_.size()
 451            << " pending outgoing messages.";
 452
 453   state_ = CONNECTING;
 454 }
 455
 456 void MCSClient::SendHeartbeat() {
 457   SendMessage(MCSMessage(kHeartbeatPingTag, mcs_proto::HeartbeatPing()));
 458 }
 459
 460 void MCSClient::OnGCMUpdateFinished(bool success) {
 461   LOG_IF(ERROR, !success) << "GCM Update failed!";
 462   UMA_HISTOGRAM_BOOLEAN("GCM.StoreUpdateSucceeded", success);
 463   // TODO(zea): Rebuild the store from scratch in case of persistence failure?
 464 }
 465
 466 void MCSClient::MaybeSendMessage() {
 467   if (to_send_.empty())
 468     return;
 469
 470   // If the connection has been reset, do nothing. On reconnection
 471   // MaybeSendMessage will be automatically invoked again.
 472   // TODO(zea): consider doing TTL expiration at connection reset time, rather
 473   // than reconnect time.
 474   if (!connection_factory_->IsEndpointReachable())
 475     return;
 476
 477   MCSPacketInternal packet = PopMessageForSend();
 478   if (HasTTLExpired(*packet->protobuf, clock_)) {
 479     DCHECK(!packet->persistent_id.empty());
 480     DVLOG(1) << "Dropping expired message " << packet->persistent_id << ".";
 481     NotifyMessageSendStatus(*packet->protobuf, TTL_EXCEEDED);
 482     gcm_store_->RemoveOutgoingMessage(
 483         packet->persistent_id,
 484         base::Bind(&MCSClient::OnGCMUpdateFinished,
 485                    weak_ptr_factory_.GetWeakPtr()));
 486     base::MessageLoop::current()->PostTask(
 487             FROM_HERE,
 488             base::Bind(&MCSClient::MaybeSendMessage,
 489                        weak_ptr_factory_.GetWeakPtr()));
 490     return;
 491   }
 492   DVLOG(1) << "Pending output message found, sending.";
 493   if (!packet->persistent_id.empty())
 494     to_resend_.push_back(packet);
 495   SendPacketToWire(packet.get());
 496 }
 497
 498 void MCSClient::SendPacketToWire(ReliablePacketInfo* packet_info) {
 499   packet_info->stream_id = ++stream_id_out_;
 500   DVLOG(1) << "Sending packet of type " << packet_info->protobuf->GetTypeName();
 501
 502   // Set the queued time as necessary.
 503   if (packet_info->tag == kDataMessageStanzaTag) {
 504     mcs_proto::DataMessageStanza* data_message =
 505         reinterpret_cast<mcs_proto::DataMessageStanza*>(
 506             packet_info->protobuf.get());
 507     uint64 sent = data_message->sent();
 508     DCHECK_GT(sent, 0U);
 509     int queued = (clock_->Now().ToInternalValue() /
 510         base::Time::kMicrosecondsPerSecond) - sent;
 511     DVLOG(1) << "Message was queued for " << queued << " seconds.";
 512     data_message->set_queued(queued);
 513     recorder_->RecordDataSentToWire(
 514         data_message->category(),
 515         data_message->to(),
 516         data_message->id(),
 517         queued);
 518   }
 519
 520   // Set the proper last received stream id to acknowledge received server
 521   // packets.
 522   DVLOG(1) << "Setting last stream id received to "
 523            << stream_id_in_;
 524   SetLastStreamIdReceived(stream_id_in_,
 525                           packet_info->protobuf.get());
 526   if (stream_id_in_ != last_server_to_device_stream_id_received_) {
 527     last_server_to_device_stream_id_received_ = stream_id_in_;
 528     // Mark all acknowledged server messages as such. Note: they're not dropped,
 529     // as it may be that they'll need to be re-acked if this message doesn't
 530     // make it.
 531     PersistentIdList persistent_id_list;
 532     for (StreamIdToPersistentIdMap::const_iterator iter =
 533              unacked_server_ids_.begin();
 534          iter != unacked_server_ids_.end(); ++iter) {
 535       DCHECK_LE(iter->first, last_server_to_device_stream_id_received_);
 536       persistent_id_list.push_back(iter->second);
 537     }
 538     unacked_server_ids_.clear();
 539     acked_server_ids_[stream_id_out_] = persistent_id_list;
 540   }
 541
 542   connection_handler_->SendMessage(*packet_info->protobuf);
 543 }
 544
 545 void MCSClient::HandleMCSDataMesssage(
 546     scoped_ptr<google::protobuf::MessageLite> protobuf) {
 547   mcs_proto::DataMessageStanza* data_message =
 548       reinterpret_cast<mcs_proto::DataMessageStanza*>(protobuf.get());
 549   // TODO(zea): implement a proper status manager rather than hardcoding these
 550   // values.
 551   scoped_ptr<mcs_proto::DataMessageStanza> response(
 552       new mcs_proto::DataMessageStanza());
 553   response->set_from(kGCMFromField);
 554   response->set_sent(clock_->Now().ToInternalValue() /
 555                          base::Time::kMicrosecondsPerSecond);
 556   response->set_ttl(0);
 557   bool send = false;
 558   for (int i = 0; i < data_message->app_data_size(); ++i) {
 559     const mcs_proto::AppData& app_data = data_message->app_data(i);
 560     if (app_data.key() == kIdleNotification) {
 561       // Tell the MCS server the client is not idle.
 562       send = true;
 563       mcs_proto::AppData data;
 564       data.set_key(kIdleNotification);
 565       data.set_value("false");
 566       response->add_app_data()->CopyFrom(data);
 567       response->set_category(kMCSCategory);
 568     }
 569   }
 570
 571   if (send) {
 572     SendMessage(MCSMessage(kDataMessageStanzaTag, response.Pass()));
 573   }
 574 }
 575
 576 void MCSClient::HandlePacketFromWire(
 577     scoped_ptr<google::protobuf::MessageLite> protobuf) {
 578   if (!protobuf.get())
 579     return;
 580   uint8 tag = GetMCSProtoTag(*protobuf);
 581   PersistentId persistent_id = GetPersistentId(*protobuf);
 582   StreamId last_stream_id_received = GetLastStreamIdReceived(*protobuf);
 583
 584   if (last_stream_id_received != 0) {
 585     last_device_to_server_stream_id_received_ = last_stream_id_received;
 586
 587     // Process device to server messages that have now been acknowledged by the
 588     // server. Because messages are stored in order, just pop off all that have
 589     // a stream id lower than server's last received stream id.
 590     HandleStreamAck(last_stream_id_received);
 591
 592     // Process server_to_device_messages that the server now knows were
 593     // acknowledged. Again, they're in order, so just keep going until the
 594     // stream id is reached.
 595     StreamIdList acked_stream_ids_to_remove;
 596     for (std::map<StreamId, PersistentIdList>::iterator iter =
 597              acked_server_ids_.begin();
 598          iter != acked_server_ids_.end() &&
 599              iter->first <= last_stream_id_received; ++iter) {
 600       acked_stream_ids_to_remove.push_back(iter->first);
 601     }
 602     for (StreamIdList::iterator iter = acked_stream_ids_to_remove.begin();
 603          iter != acked_stream_ids_to_remove.end(); ++iter) {
 604       acked_server_ids_.erase(*iter);
 605     }
 606   }
 607
 608   ++stream_id_in_;
 609   if (!persistent_id.empty()) {
 610     unacked_server_ids_[stream_id_in_] = persistent_id;
 611     gcm_store_->AddIncomingMessage(persistent_id,
 612                                    base::Bind(&MCSClient::OnGCMUpdateFinished,
 613                                               weak_ptr_factory_.GetWeakPtr()));
 614   }
 615
 616   DVLOG(1) << "Received message of type " << protobuf->GetTypeName()
 617            << " with persistent id "
 618            << (persistent_id.empty() ? "NULL" : persistent_id)
 619            << ", stream id " << stream_id_in_ << " and last stream id received "
 620            << last_stream_id_received;
 621
 622   if (unacked_server_ids_.size() > 0 &&
 623       unacked_server_ids_.size() % kUnackedMessageBeforeStreamAck == 0) {
 624     SendMessage(MCSMessage(kIqStanzaTag, BuildStreamAck()));
 625   }
 626
 627   // The connection is alive, treat this message as a heartbeat ack.
 628   heartbeat_manager_.OnHeartbeatAcked();
 629
 630   switch (tag) {
 631     case kLoginResponseTag: {
 632       DCHECK_EQ(CONNECTING, state_);
 633       mcs_proto::LoginResponse* login_response =
 634           reinterpret_cast<mcs_proto::LoginResponse*>(protobuf.get());
 635       DVLOG(1) << "Received login response:";
 636       DVLOG(1) << "  Id: " << login_response->id();
 637       DVLOG(1) << "  Timestamp: " << login_response->server_timestamp();
 638       if (login_response->has_error() && login_response->error().code() != 0) {
 639         state_ = UNINITIALIZED;
 640         DVLOG(1) << "  Error code: " << login_response->error().code();
 641         DVLOG(1) << "  Error message: " << login_response->error().message();
 642         LOG(ERROR) << "Failed to log in to GCM, resetting connection.";
 643         connection_factory_->SignalConnectionReset(
 644             ConnectionFactory::LOGIN_FAILURE);
 645         mcs_error_callback_.Run();
 646         return;
 647       }
 648
 649       if (login_response->has_heartbeat_config()) {
 650         heartbeat_manager_.UpdateHeartbeatConfig(
 651             login_response->heartbeat_config());
 652       }
 653
 654       state_ = CONNECTED;
 655       stream_id_in_ = 1;  // To account for the login response.
 656       DCHECK_EQ(1U, stream_id_out_);
 657
 658       // Pass the login response on up.
 659       base::MessageLoop::current()->PostTask(
 660           FROM_HERE,
 661           base::Bind(message_received_callback_,
 662                      MCSMessage(tag, protobuf.Pass())));
 663
 664       // If there are pending messages, attempt to send one.
 665       if (!to_send_.empty()) {
 666         base::MessageLoop::current()->PostTask(
 667             FROM_HERE,
 668             base::Bind(&MCSClient::MaybeSendMessage,
 669                        weak_ptr_factory_.GetWeakPtr()));
 670       }
 671
 672       heartbeat_manager_.Start(
 673           base::Bind(&MCSClient::SendHeartbeat,
 674                      weak_ptr_factory_.GetWeakPtr()),
 675           base::Bind(&MCSClient::OnConnectionResetByHeartbeat,
 676                      weak_ptr_factory_.GetWeakPtr()));
 677       return;
 678     }
 679     case kHeartbeatPingTag:
 680       DCHECK_GE(stream_id_in_, 1U);
 681       DVLOG(1) << "Received heartbeat ping, sending ack.";
 682       SendMessage(
 683           MCSMessage(kHeartbeatAckTag, mcs_proto::HeartbeatAck()));
 684       return;
 685     case kHeartbeatAckTag:
 686       DCHECK_GE(stream_id_in_, 1U);
 687       DVLOG(1) << "Received heartbeat ack.";
 688       // Do nothing else, all messages act as heartbeat acks.
 689       return;
 690     case kCloseTag:
 691       LOG(ERROR) << "Received close command, resetting connection.";
 692       state_ = LOADED;
 693       connection_factory_->SignalConnectionReset(
 694           ConnectionFactory::CLOSE_COMMAND);
 695       return;
 696     case kIqStanzaTag: {
 697       DCHECK_GE(stream_id_in_, 1U);
 698       mcs_proto::IqStanza* iq_stanza =
 699           reinterpret_cast<mcs_proto::IqStanza*>(protobuf.get());
 700       const mcs_proto::Extension& iq_extension = iq_stanza->extension();
 701       switch (iq_extension.id()) {
 702         case kSelectiveAck: {
 703           PersistentIdList acked_ids;
 704           if (BuildPersistentIdListFromProto(iq_extension.data(),
 705                                              &acked_ids)) {
 706             HandleSelectiveAck(acked_ids);
 707           }
 708           return;
 709         }
 710         case kStreamAck:
 711           // Do nothing. The last received stream id is always processed if it's
 712           // present.
 713           return;
 714         default:
 715           LOG(WARNING) << "Received invalid iq stanza extension "
 716                        << iq_extension.id();
 717           return;
 718       }
 719     }
 720     case kDataMessageStanzaTag: {
 721       DCHECK_GE(stream_id_in_, 1U);
 722       mcs_proto::DataMessageStanza* data_message =
 723           reinterpret_cast<mcs_proto::DataMessageStanza*>(protobuf.get());
 724       if (data_message->category() == kMCSCategory) {
 725         HandleMCSDataMesssage(protobuf.Pass());
 726         return;
 727       }
 728
 729       DCHECK(protobuf.get());
 730       base::MessageLoop::current()->PostTask(
 731           FROM_HERE,
 732           base::Bind(message_received_callback_,
 733                      MCSMessage(tag, protobuf.Pass())));
 734       return;
 735     }
 736     default:
 737       LOG(ERROR) << "Received unexpected message of type "
 738                  << static_cast<int>(tag);
 739       return;
 740   }
 741 }
 742
 743 void MCSClient::HandleStreamAck(StreamId last_stream_id_received) {
 744   PersistentIdList acked_outgoing_persistent_ids;
 745   StreamIdList acked_outgoing_stream_ids;
 746   while (!to_resend_.empty() &&
 747          to_resend_.front()->stream_id <= last_stream_id_received) {
 748     const MCSPacketInternal& outgoing_packet = to_resend_.front();
 749     acked_outgoing_persistent_ids.push_back(outgoing_packet->persistent_id);
 750     acked_outgoing_stream_ids.push_back(outgoing_packet->stream_id);
 751     NotifyMessageSendStatus(*outgoing_packet->protobuf, SENT);
 752     to_resend_.pop_front();
 753   }
 754
 755   DVLOG(1) << "Server acked " << acked_outgoing_persistent_ids.size()
 756            << " outgoing messages, " << to_resend_.size()
 757            << " remaining unacked";
 758   gcm_store_->RemoveOutgoingMessages(
 759       acked_outgoing_persistent_ids,
 760       base::Bind(&MCSClient::OnGCMUpdateFinished,
 761                  weak_ptr_factory_.GetWeakPtr()));
 762
 763   HandleServerConfirmedReceipt(last_stream_id_received);
 764 }
 765
 766 void MCSClient::HandleSelectiveAck(const PersistentIdList& id_list) {
 767   std::set<PersistentId> remaining_ids(id_list.begin(), id_list.end());
 768
 769   StreamId last_stream_id_received = 0;
 770
 771   // First check the to_resend_ queue. Acknowledgments are always contiguous,
 772   // so if there's a pending message that hasn't been acked, all newer messages
 773   // must also be unacked.
 774   while(!to_resend_.empty() && !remaining_ids.empty()) {
 775     const MCSPacketInternal& outgoing_packet = to_resend_.front();
 776     if (remaining_ids.count(outgoing_packet->persistent_id) == 0)
 777       break;  // Newer message must be unacked too.
 778     remaining_ids.erase(outgoing_packet->persistent_id);
 779     NotifyMessageSendStatus(*outgoing_packet->protobuf, SENT);
 780
 781     // No need to re-acknowledge any server messages this message already
 782     // acknowledged.
 783     StreamId device_stream_id = outgoing_packet->stream_id;
 784     if (device_stream_id > last_stream_id_received)
 785       last_stream_id_received = device_stream_id;
 786     to_resend_.pop_front();
 787   }
 788
 789   // If the acknowledged ids aren't all there, they might be in the to_send_
 790   // queue (typically when a SelectiveAck confirms messages as part of a login
 791   // response).
 792   while (!to_send_.empty() && !remaining_ids.empty()) {
 793     const MCSPacketInternal& outgoing_packet = to_send_.front();
 794     if (remaining_ids.count(outgoing_packet->persistent_id) == 0)
 795       break;  // Newer messages must be unacked too.
 796     remaining_ids.erase(outgoing_packet->persistent_id);
 797     NotifyMessageSendStatus(*outgoing_packet->protobuf, SENT);
 798
 799     // No need to re-acknowledge any server messages this message already
 800     // acknowledged.
 801     StreamId device_stream_id = outgoing_packet->stream_id;
 802     if (device_stream_id > last_stream_id_received)
 803       last_stream_id_received = device_stream_id;
 804     PopMessageForSend();
 805   }
 806
 807   // Only handle the largest stream id value. All other stream ids are
 808   // implicitly handled.
 809   if (last_stream_id_received > 0)
 810     HandleServerConfirmedReceipt(last_stream_id_received);
 811
 812   // At this point, all remaining acked ids are redundant.
 813   PersistentIdList acked_ids;
 814   if (remaining_ids.size() > 0) {
 815     for (size_t i = 0; i < id_list.size(); ++i) {
 816       if (remaining_ids.count(id_list[i]) > 0)
 817         continue;
 818       acked_ids.push_back(id_list[i]);
 819     }
 820   } else {
 821     acked_ids = id_list;
 822   }
 823
 824   DVLOG(1) << "Server acked " << acked_ids.size()
 825            << " messages, " << to_resend_.size() << " remaining unacked.";
 826   gcm_store_->RemoveOutgoingMessages(
 827       acked_ids,
 828       base::Bind(&MCSClient::OnGCMUpdateFinished,
 829                  weak_ptr_factory_.GetWeakPtr()));
 830
 831   // Resend any remaining outgoing messages, as they were not received by the
 832   // server.
 833   DVLOG(1) << "Resending " << to_resend_.size() << " messages.";
 834   while (!to_resend_.empty()) {
 835     to_send_.push_front(to_resend_.back());
 836     to_resend_.pop_back();
 837   }
 838   base::MessageLoop::current()->PostTask(
 839       FROM_HERE,
 840       base::Bind(&MCSClient::MaybeSendMessage,
 841                  weak_ptr_factory_.GetWeakPtr()));
 842 }
 843
 844 void MCSClient::HandleServerConfirmedReceipt(StreamId device_stream_id) {
 845   PersistentIdList acked_incoming_ids;
 846   for (std::map<StreamId, PersistentIdList>::iterator iter =
 847            acked_server_ids_.begin();
 848        iter != acked_server_ids_.end() &&
 849            iter->first <= device_stream_id;) {
 850     acked_incoming_ids.insert(acked_incoming_ids.end(),
 851                               iter->second.begin(),
 852                               iter->second.end());
 853     acked_server_ids_.erase(iter++);
 854   }
 855
 856   DVLOG(1) << "Server confirmed receipt of " << acked_incoming_ids.size()
 857            << " acknowledged server messages.";
 858   gcm_store_->RemoveIncomingMessages(
 859       acked_incoming_ids,
 860       base::Bind(&MCSClient::OnGCMUpdateFinished,
 861                  weak_ptr_factory_.GetWeakPtr()));
 862 }
 863
 864 MCSClient::PersistentId MCSClient::GetNextPersistentId() {
 865   return base::Uint64ToString(base::TimeTicks::Now().ToInternalValue());
 866 }
 867
 868 void MCSClient::OnConnectionResetByHeartbeat() {
 869   connection_factory_->SignalConnectionReset(
 870       ConnectionFactory::HEARTBEAT_FAILURE);
 871 }
 872
 873 void MCSClient::NotifyMessageSendStatus(
 874     const google::protobuf::MessageLite& protobuf,
 875     MessageSendStatus status) {
 876   if (GetMCSProtoTag(protobuf) != kDataMessageStanzaTag)
 877     return;
 878
 879   const mcs_proto::DataMessageStanza* data_message_stanza =
 880       reinterpret_cast<const mcs_proto::DataMessageStanza*>(&protobuf);
 881   recorder_->RecordNotifySendStatus(
 882       data_message_stanza->category(),
 883       data_message_stanza->to(),
 884       data_message_stanza->id(),
 885       status,
 886       protobuf.ByteSize(),
 887       data_message_stanza->ttl());
 888   message_sent_callback_.Run(
 889       data_message_stanza->device_user_id(),
 890       data_message_stanza->category(),
 891       data_message_stanza->id(),
 892       status);
 893 }
 894
 895 MCSClient::MCSPacketInternal MCSClient::PopMessageForSend() {
 896   MCSPacketInternal packet = to_send_.front();
 897   to_send_.pop_front();
 898
 899   if (packet->tag == kDataMessageStanzaTag) {
 900     mcs_proto::DataMessageStanza* data_message =
 901         reinterpret_cast<mcs_proto::DataMessageStanza*>(packet->protobuf.get());
 902     CollapseKey collapse_key(*data_message);
 903     if (collapse_key.IsValid())
 904       collapse_key_map_.erase(collapse_key);
 905   }
 906
 907   return packet;
 908 }
 909
 910 } // namespace gcm