git.m6w6.name Git - awesomized/libmemcached/blob - src/libmemcached/udp.cc

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  LibMemcached
   4  *
   5  *  Copyright (C) 2011 Data Differential, http://datadifferential.com/
   6  *  All rights reserved.
   7  *
   8  *  Redistribution and use in source and binary forms, with or without
   9  *  modification, are permitted provided that the following conditions are
  10  *  met:
  11  *
  12  *      * Redistributions of source code must retain the above copyright
  13  *  notice, this list of conditions and the following disclaimer.
  14  *
  15  *      * Redistributions in binary form must reproduce the above
  16  *  copyright notice, this list of conditions and the following disclaimer
  17  *  in the documentation and/or other materials provided with the
  18  *  distribution.
  19  *
  20  *      * The names of its contributors may not be used to endorse or
  21  *  promote products derived from this software without specific prior
  22  *  written permission.
  23  *
  24  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  25  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  26  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  27  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  28  *  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  30  *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  34  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  *
  36  */
  37
  38 #include "libmemcached/common.h"
  39
  40 /*
  41  * The udp request id consists of two seperate sections
  42  *   1) The thread id
  43  *   2) The message number
  44  * The thread id should only be set when the memcached_st struct is created
  45  * and should not be changed.
  46  *
  47  * The message num is incremented for each new message we send, this function
  48  * extracts the message number from message_id, increments it and then
  49  * writes the new value back into the header
  50  */
  51 void increment_udp_message_id(memcached_instance_st* ptr)
  52 {
  53   struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
  54   uint16_t cur_req= get_udp_datagram_request_id(header);
  55   int msg_num= get_msg_num_from_request_id(cur_req);
  56   int thread_id= get_thread_id_from_request_id(cur_req);
  57
  58   if (((++msg_num) & UDP_REQUEST_ID_THREAD_MASK) != 0)
  59     msg_num= 0;
  60
  61   header->request_id= htons((uint16_t) (thread_id | msg_num));
  62 }
  63
  64 bool memcached_io_init_udp_header(memcached_instance_st* ptr, const uint16_t thread_id)
  65 {
  66   if (thread_id > UDP_REQUEST_ID_MAX_THREAD_ID)
  67   {
  68     return MEMCACHED_FAILURE;
  69   }
  70
  71   struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
  72   header->request_id= htons(uint16_t((generate_udp_request_thread_id(thread_id))));
  73   header->num_datagrams= htons(1);
  74   header->sequence_number= htons(0);
  75
  76   return MEMCACHED_SUCCESS;
  77 }