path: root/net/base/tcp_client_socket_pool.cc

// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/base/tcp_client_socket_pool.h"

#include "base/compiler_specific.h"
#include "base/field_trial.h"
#include "base/message_loop.h"
#include "base/time.h"
#include "base/stl_util-inl.h"
#include "net/base/client_socket_factory.h"
#include "net/base/client_socket_handle.h"
#include "net/base/net_errors.h"
#include "net/base/tcp_client_socket.h"

using base::TimeDelta;

namespace {

// The timeout value, in seconds, used to clean up idle sockets that can't be
// reused.
//
// Note: It's important to close idle sockets that have received data as soon
// as possible because the received data may cause BSOD on Windows XP under
// some conditions.  See http://crbug.com/4606.
const int kCleanupInterval = 10;  // DO NOT INCREASE THIS TIMEOUT.

// The maximum duration, in seconds, to keep idle persistent sockets alive.
const int kIdleTimeout = 300;  // 5 minutes.

}  // namespace

namespace net {

TCPConnectingSocket::TCPConnectingSocket(
    const std::string& group_name,
    const HostResolver::RequestInfo& resolve_info,
    const ClientSocketHandle* handle,
    ClientSocketFactory* client_socket_factory,
    ClientSocketPoolBase* pool)
    : group_name_(group_name),
      resolve_info_(resolve_info),
      handle_(handle),
      client_socket_factory_(client_socket_factory),
      ALLOW_THIS_IN_INITIALIZER_LIST(
          callback_(this,
                    &TCPConnectingSocket::OnIOComplete)),
      pool_(pool),
      resolver_(pool->GetHostResolver()) {}

TCPConnectingSocket::~TCPConnectingSocket() {
  // We don't worry about cancelling the host resolution and TCP connect, since
  // ~SingleRequestHostResolver and ~ClientSocket will take care of it.
}

int TCPConnectingSocket::Connect() {
  int rv = resolver_.Resolve(resolve_info_, &addresses_, &callback_);
  if (rv != ERR_IO_PENDING)
    rv = OnIOCompleteInternal(rv, true /* synchronous */);
  return rv;
}

void TCPConnectingSocket::OnIOComplete(int result) {
  OnIOCompleteInternal(result, false /* asynchronous */);
}

int TCPConnectingSocket::OnIOCompleteInternal(
    int result, bool synchronous) {
  CHECK(result != ERR_IO_PENDING);

  ClientSocketPoolBase::Request* request = pool_->GetConnectingRequest(
      group_name_, handle_);
  CHECK(request);

  if (result == OK && request->load_state == LOAD_STATE_RESOLVING_HOST) {
    request->load_state = LOAD_STATE_CONNECTING;
    socket_.reset(client_socket_factory_->CreateTCPClientSocket(addresses_));
    connect_start_time_ = base::TimeTicks::Now();
    result = socket_->Connect(&callback_);
    if (result == ERR_IO_PENDING)
      return result;
  }

  if (result == OK) {
    CHECK(request->load_state == LOAD_STATE_CONNECTING);
    CHECK(connect_start_time_ != base::TimeTicks());
    base::TimeDelta connect_duration =
        base::TimeTicks::Now() - connect_start_time_;

    UMA_HISTOGRAM_CLIPPED_TIMES("Net.TCP_Connection_Latency",
        connect_duration,
        base::TimeDelta::FromMilliseconds(1),
        base::TimeDelta::FromMinutes(10),
        100);
  }

  // Now, we either succeeded at Connect()'ing, or we failed at host resolution
  // or Connect()'ing.  Either way, we'll run the callback to alert the client.

  CompletionCallback* callback = NULL;

  if (result == OK) {
    callback = pool_->OnConnectingRequestComplete(
        group_name_,
        handle_,
        false /* don't deactivate socket */,
        socket_.release());
  } else {
    callback = pool_->OnConnectingRequestComplete(
        group_name_,
        handle_,
        true /* deactivate socket */,
        NULL /* no connected socket to give */);
  }

  // |this| is deleted after this point.

  CHECK(callback);

  if (!synchronous)
    callback->Run(result);
  return result;
}

ClientSocketPoolBase::ClientSocketPoolBase(
    int max_sockets_per_group,
    HostResolver* host_resolver,
    ConnectingSocketFactory* connecting_socket_factory)
    : idle_socket_count_(0),
      max_sockets_per_group_(max_sockets_per_group),
      host_resolver_(host_resolver),
      connecting_socket_factory_(connecting_socket_factory) {}

ClientSocketPoolBase::~ClientSocketPoolBase() {
  // Clean up any idle sockets.  Assert that we have no remaining active
  // sockets or pending requests.  They should have all been cleaned up prior
  // to the manager being destroyed.
  CloseIdleSockets();
  DCHECK(group_map_.empty());
  DCHECK(connecting_socket_map_.empty());
}

// InsertRequestIntoQueue inserts the request into the queue based on
// priority.  Highest priorities are closest to the front.  Older requests are
// prioritized over requests of equal priority.
//
// static
void ClientSocketPoolBase::InsertRequestIntoQueue(
    const Request& r, RequestQueue* pending_requests) {
  RequestQueue::iterator it = pending_requests->begin();
  while (it != pending_requests->end() && r.priority <= it->priority)
    ++it;
  pending_requests->insert(it, r);
}

int ClientSocketPoolBase::RequestSocket(
    const std::string& group_name,
    const HostResolver::RequestInfo& resolve_info,
    int priority,
    ClientSocketHandle* handle,
    CompletionCallback* callback) {
  DCHECK(!resolve_info.hostname().empty());
  DCHECK_GE(priority, 0);
  Group& group = group_map_[group_name];

  CheckSocketCounts(group);

  // Can we make another active socket now?
  if (group.active_socket_count == max_sockets_per_group_) {
    CHECK(callback);
    Request r(handle, callback, priority, resolve_info, LOAD_STATE_IDLE);
    InsertRequestIntoQueue(r, &group.pending_requests);
    return ERR_IO_PENDING;
  }

  // OK, we are going to activate one.
  group.active_socket_count++;

  while (!group.idle_sockets.empty()) {
    IdleSocket idle_socket = group.idle_sockets.back();
    group.idle_sockets.pop_back();
    DecrementIdleCount();
    if (idle_socket.socket->IsConnectedAndIdle()) {
      // We found one we can reuse!
      handle->set_socket(idle_socket.socket);
      handle->set_is_reused(true);
      group.sockets_handed_out_count++;
      CHECK(group.sockets_handed_out_count <= group.active_socket_count);
      CheckSocketCounts(group);
      return OK;
    }
    delete idle_socket.socket;
  }

  // We couldn't find a socket to reuse, so allocate and connect a new one.

  CHECK(callback);
  Request r(handle, callback, priority, resolve_info,
            LOAD_STATE_RESOLVING_HOST);
  group.connecting_requests[handle] = r;

  CHECK(!ContainsKey(connecting_socket_map_, handle));

  ConnectingSocket* connecting_socket =
      connecting_socket_factory_->NewConnectingSocket(group_name, r, this);
  connecting_socket_map_[handle] = connecting_socket;
  int rv = connecting_socket->Connect();

  CheckSocketCounts(group);
  return rv;
}

void ClientSocketPoolBase::CancelRequest(const std::string& group_name,
                                         const ClientSocketHandle* handle) {
  CHECK(handle);
  CHECK(ContainsKey(group_map_, group_name));

  Group& group = group_map_[group_name];

  CheckSocketCounts(group);

  // Search pending_requests for matching handle.
  RequestQueue::iterator it = group.pending_requests.begin();
  for (; it != group.pending_requests.end(); ++it) {
    if (it->handle == handle) {
      group.pending_requests.erase(it);
      return;
    }
  }

  // It's invalid to cancel a non-existent request.
  CHECK(ContainsKey(group.connecting_requests, handle));

  RequestMap::iterator map_it = group.connecting_requests.find(handle);
  RemoveConnectingSocket(handle);

  CheckSocketCounts(group);
  group.connecting_requests.erase(map_it);
  group.active_socket_count--;
  CheckSocketCounts(group);

  // Delete group if no longer needed.
  if (group.active_socket_count == 0 && group.idle_sockets.empty()) {
    CHECK(group.pending_requests.empty());
    CHECK(group.sockets_handed_out_count == 0);
    CHECK(group.connecting_requests.size() == 0);
    CHECK(group.connecting_requests.empty());
    group_map_.erase(group_name);
    return;
  }

  CheckSocketCounts(group);
}

void ClientSocketPoolBase::ReleaseSocket(const std::string& group_name,
                                         ClientSocket* socket) {
  // Run this asynchronously to allow the caller to finish before we let
  // another to begin doing work.  This also avoids nasty recursion issues.
  // NOTE: We cannot refer to the handle argument after this method returns.
  MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
      this, &ClientSocketPoolBase::DoReleaseSocket, group_name, socket));
}

void ClientSocketPoolBase::CloseIdleSockets() {
  CleanupIdleSockets(true);
}

int ClientSocketPoolBase::IdleSocketCountInGroup(
    const std::string& group_name) const {
  GroupMap::const_iterator i = group_map_.find(group_name);
  CHECK(i != group_map_.end());

  return i->second.idle_sockets.size();
}

LoadState ClientSocketPoolBase::GetLoadState(
    const std::string& group_name,
    const ClientSocketHandle* handle) const {
  if (!ContainsKey(group_map_, group_name)) {
    NOTREACHED() << "ClientSocketPool does not contain group: " << group_name
                 << " for handle: " << handle;
    return LOAD_STATE_IDLE;
  }

  // Can't use operator[] since it is non-const.
  const Group& group = group_map_.find(group_name)->second;

  // Search connecting_requests for matching handle.
  RequestMap::const_iterator map_it = group.connecting_requests.find(handle);
  if (map_it != group.connecting_requests.end()) {
    const LoadState load_state = map_it->second.load_state;
    CHECK(load_state == LOAD_STATE_RESOLVING_HOST ||
          load_state == LOAD_STATE_CONNECTING);
    return load_state;
  }

  // Search pending_requests for matching handle.
  RequestQueue::const_iterator it = group.pending_requests.begin();
  for (; it != group.pending_requests.end(); ++it) {
    if (it->handle == handle) {
      CHECK(LOAD_STATE_IDLE == it->load_state);
      // TODO(wtc): Add a state for being on the wait list.
      // See http://www.crbug.com/5077.
      return LOAD_STATE_IDLE;
    }
  }

  NOTREACHED();
  return LOAD_STATE_IDLE;
}

bool ClientSocketPoolBase::IdleSocket::ShouldCleanup(
    base::TimeTicks now) const {
  bool timed_out = (now - start_time) >=
      base::TimeDelta::FromSeconds(kIdleTimeout);
  return timed_out || !socket->IsConnectedAndIdle();
}

void ClientSocketPoolBase::CleanupIdleSockets(bool force) {
  if (idle_socket_count_ == 0)
    return;

  // Current time value. Retrieving it once at the function start rather than
  // inside the inner loop, since it shouldn't change by any meaningful amount.
  base::TimeTicks now = base::TimeTicks::Now();

  GroupMap::iterator i = group_map_.begin();
  while (i != group_map_.end()) {
    Group& group = i->second;

    std::deque<IdleSocket>::iterator j = group.idle_sockets.begin();
    while (j != group.idle_sockets.end()) {
      if (force || j->ShouldCleanup(now)) {
        delete j->socket;
        j = group.idle_sockets.erase(j);
        DecrementIdleCount();
      } else {
        ++j;
      }
    }

    // Delete group if no longer needed.
    if (group.active_socket_count == 0 && group.idle_sockets.empty()) {
      CHECK(group.pending_requests.empty());
      CHECK(group.connecting_requests.empty());
      group_map_.erase(i++);
    } else {
      ++i;
    }
  }
}

void ClientSocketPoolBase::IncrementIdleCount() {
  if (++idle_socket_count_ == 1)
    timer_.Start(TimeDelta::FromSeconds(kCleanupInterval), this,
                 &ClientSocketPoolBase::OnCleanupTimerFired);
}

void ClientSocketPoolBase::DecrementIdleCount() {
  if (--idle_socket_count_ == 0)
    timer_.Stop();
}

void ClientSocketPoolBase::DoReleaseSocket(const std::string& group_name,
                                           ClientSocket* socket) {
  GroupMap::iterator i = group_map_.find(group_name);
  CHECK(i != group_map_.end());

  Group& group = i->second;

  CHECK(group.active_socket_count > 0);
  CheckSocketCounts(group);

  group.active_socket_count--;
  group.sockets_handed_out_count--;
  CHECK(group.sockets_handed_out_count >= 0);

  const bool can_reuse = socket->IsConnectedAndIdle();
  if (can_reuse) {
    IdleSocket idle_socket;
    idle_socket.socket = socket;
    idle_socket.start_time = base::TimeTicks::Now();

    group.idle_sockets.push_back(idle_socket);
    IncrementIdleCount();
  } else {
    delete socket;
  }

  // Process one pending request.
  if (!group.pending_requests.empty()) {
    Request r = group.pending_requests.front();
    group.pending_requests.pop_front();

    int rv = RequestSocket(
        group_name, r.resolve_info, r.priority, r.handle, r.callback);

    CheckSocketCounts(group);

    if (rv != ERR_IO_PENDING)
      r.callback->Run(rv);
    return;
  }

  // Delete group if no longer needed.
  if (group.active_socket_count == 0 && group.idle_sockets.empty()) {
    CHECK(group.pending_requests.empty());
    CHECK(group.connecting_requests.empty());
    group_map_.erase(i);
  } else {
    CheckSocketCounts(group);
  }
}

ClientSocketPoolBase::Request* ClientSocketPoolBase::GetConnectingRequest(
    const std::string& group_name, const ClientSocketHandle* handle) {
  GroupMap::iterator group_it = group_map_.find(group_name);
  if (group_it == group_map_.end())
    return NULL;

  Group& group = group_it->second;

  RequestMap* request_map = &group.connecting_requests;
  RequestMap::iterator it = request_map->find(handle);
  if (it == request_map->end())
    return NULL;

  return &it->second;
}

CompletionCallback* ClientSocketPoolBase::OnConnectingRequestComplete(
    const std::string& group_name,
    const ClientSocketHandle* handle,
    bool deactivate,
    ClientSocket* socket) {
  CHECK((deactivate && !socket) || (!deactivate && socket));
  GroupMap::iterator group_it = group_map_.find(group_name);
  CHECK(group_it != group_map_.end());
  Group& group = group_it->second;

  CheckSocketCounts(group);

  RequestMap* request_map = &group.connecting_requests;

  RequestMap::iterator it = request_map->find(handle);
  CHECK(it != request_map->end());
  Request request = it->second;
  request_map->erase(it);
  DCHECK_EQ(request.handle, handle);

  if (deactivate) {
    group.active_socket_count--;

    // Delete group if no longer needed.
    if (group.active_socket_count == 0 && group.idle_sockets.empty()) {
      DCHECK(group.pending_requests.empty());
      DCHECK(group.connecting_requests.empty());
      group_map_.erase(group_name);
    } else {
      CheckSocketCounts(group);
    }
  } else {
    request.handle->set_socket(socket);
    request.handle->set_is_reused(false);
    group.sockets_handed_out_count++;
    CHECK(group.sockets_handed_out_count <= group.active_socket_count);

    CheckSocketCounts(group);
  }

  RemoveConnectingSocket(request.handle);

  return request.callback;
}

// static
void ClientSocketPoolBase::CheckSocketCounts(const Group& group) {
  CHECK(group.active_socket_count ==
        group.sockets_handed_out_count +
        static_cast<int>(group.connecting_requests.size()))
      << "[active_socket_count: " << group.active_socket_count
      << " ] [sockets_handed_out_count: " << group.sockets_handed_out_count
      << " ] [connecting_requests size: " << group.connecting_requests.size();
}

void ClientSocketPoolBase::RemoveConnectingSocket(
    const ClientSocketHandle* handle) {
  ConnectingSocketMap::iterator it = connecting_socket_map_.find(handle);
  CHECK(it != connecting_socket_map_.end());
  delete it->second;
  connecting_socket_map_.erase(it);
}

ConnectingSocket*
TCPClientSocketPool::TCPConnectingSocketFactory::NewConnectingSocket(
    const std::string& group_name,
    const ClientSocketPoolBase::Request& request,
    ClientSocketPoolBase* pool) const {
  return new TCPConnectingSocket(
      group_name, request.resolve_info, request.handle,
      client_socket_factory_, pool);
}

TCPClientSocketPool::TCPClientSocketPool(
    int max_sockets_per_group,
    HostResolver* host_resolver,
    ClientSocketFactory* client_socket_factory)
    : base_(new ClientSocketPoolBase(
        max_sockets_per_group, host_resolver,
        new TCPConnectingSocketFactory(client_socket_factory))) {}

TCPClientSocketPool::~TCPClientSocketPool() {}

int TCPClientSocketPool::RequestSocket(
    const std::string& group_name,
    const HostResolver::RequestInfo& resolve_info,
    int priority,
    ClientSocketHandle* handle,
    CompletionCallback* callback) {
  return base_->RequestSocket(
      group_name, resolve_info, priority, handle, callback);
}

void TCPClientSocketPool::CancelRequest(
    const std::string& group_name,
    const ClientSocketHandle* handle) {
  base_->CancelRequest(group_name, handle);
}

void TCPClientSocketPool::ReleaseSocket(
    const std::string& group_name,
    ClientSocket* socket) {
  base_->ReleaseSocket(group_name, socket);
}

void TCPClientSocketPool::CloseIdleSockets() {
  base_->CloseIdleSockets();
}

int TCPClientSocketPool::IdleSocketCountInGroup(
    const std::string& group_name) const {
  return base_->IdleSocketCountInGroup(group_name);
}

LoadState TCPClientSocketPool::GetLoadState(
    const std::string& group_name, const ClientSocketHandle* handle) const {
  return base_->GetLoadState(group_name, handle);
}

}  // namespace net