src/comm/AcceptLimiter.cc

   1 /*
   2  * Copyright (C) 1996-2017 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #include "squid.h"
  10 #include "comm/AcceptLimiter.h"
  11 #include "comm/Connection.h"
  12 #include "comm/TcpAcceptor.h"
  13 #include "fde.h"
  14 #include "globals.h"
  15
  16 Comm::AcceptLimiter Comm::AcceptLimiter::Instance_;
  17
  18 Comm::AcceptLimiter &
  19 Comm::AcceptLimiter::Instance()
  20 {
  21     return Instance_;
  22 }
  23
  24 void
  25 Comm::AcceptLimiter::defer(const Comm::TcpAcceptor::Pointer &afd)
  26 {
  27     ++ (afd->isLimited);
  28     debugs(5, 5, afd->conn << " x" << afd->isLimited);
  29     deferred_.push_back(afd);
  30 }
  31
  32 void
  33 Comm::AcceptLimiter::removeDead(const Comm::TcpAcceptor::Pointer &afd)
  34 {
  35     uint64_t abandonedClients = 0;
  36     for (unsigned int i = 0; i < deferred_.size() && afd->isLimited > 0; ++i) {
  37         if (deferred_[i] == afd) {
  38             -- deferred_[i]->isLimited;
  39             deferred_[i] = NULL; // fast. kick() will skip empty entries later.
  40             debugs(5, 5, afd->conn << " x" << afd->isLimited);
  41             ++abandonedClients;
  42         }
  43     }
  44     debugs(5,4, "Abandoned " << abandonedClients << " client TCP SYN by closing socket: " << afd->conn);
  45 }
  46
  47 void
  48 Comm::AcceptLimiter::kick()
  49 {
  50     // TODO: this could be optimized further with an iterator to search
  51     //       looking for first non-NULL, followed by dumping the first N
  52     //       with only one shift()/pop_front operation
  53     //  OR, by reimplementing as a list instead of Vector.
  54
  55     debugs(5, 5, "size=" << deferred_.size());
  56     while (deferred_.size() > 0 && fdNFree() >= RESERVED_FD) {
  57         /* NP: shift() is equivalent to pop_front(). Giving us a FIFO queue. */
  58         TcpAcceptor::Pointer temp = deferred_.front();
  59         deferred_.erase(deferred_.begin());
  60         if (temp.valid()) {
  61             debugs(5, 5, "doing one.");
  62             -- temp->isLimited;
  63             temp->acceptNext();
  64             break;
  65         }
  66     }
  67 }
  68