haudp.c

extremeDB s sample code,useful for you

/*******************************************************************
 *                                                                 *
 *  haudp.c                                                        *
 *                                                                 *
 *  This file is a part of the eXtremeDB-HA Application Framework  *
 *  Copyright (c) 2001-2006 McObject LLC                           * 
 *  All Rights Reserved                                            *
 *                                                                 *
 *******************************************************************/
/*
 * ++
 * 
 * PROJECT:   eXtremeDB(tm) (c) McObject LLC
 *
 * SUBSYSTEM: HA support
 *
 * MODULE:    haudp.c
 *
 * ABSTRACT:  Low level OS dependent IPC. Channel-over-UDP
 *
 *
 * VERSION:   1.0
 *
 * HISTORY:
 *            1.0- 1 SS     21-Jul-2003 Created it was
 *                 2 SS      8-Nov-2003 Ported to Solaris
 *                 3 SS     12-Nov-2003 Ported to WinCE
 *
 * --
 */

#define INCLUDE_SOCKETS
#include "interface.h"

#ifdef CFG_UDP_SOCKET_CHANNEL

#ifdef __cplusplus
  extern "C" { 
#endif

extern  int2  allocate_index();
extern  void  deallocate_index(int2 index);
extern  void  reallocate_index(int2 index);
extern  void  nw_attach_buffer( nw_channel_h chan, PVOID buffer, uint2 bufsize);

extern  int           cancel_flag;    // turns on "replica cancellation" feature
extern uint4          NumBytes;
extern  int           conn_flag;
extern  timer_unit    init_time;
extern  int           commit_initialized;
extern  udp_msg_buf_t msgbuf;

extern
MCO_RET nw_send_message( nw_channel_h chan,
                           const void* buffer,  int2 buflen,
                           long       timeout);
extern
MCO_RET nw_recv_message( nw_channel_h  chan,
                          const void* buffer,  int2 buflen,
                          PSHORT    recvlen,  long timeout);

#ifdef __cplusplus
  }
#endif

/***************************************************************************
 * Interface layer. Used by master - replica interconnections.             * 
 * The interface is simplified. All the internal protocol details are      *
 * hidden behind this layer from the application and MCOdb HA              * 
 ***************************************************************************/

/******************************************************************************
 * 
 * Send method of HA runtime.
 * 
 * IN nw_channel_h  ch      - pointer to a channel descriptor.
 * IN const void *  buffer  - buffer of data to send.
 * IN unsigned      buflen  - number of bytes to send
 * IN timer_unit    timeout - wait-for-send-completion timeout.

 *
 * Description:
 * This send function is used implicitly by master-replica interconnection channel.
 * The pointers to this function MUST be set to HA internal descriptor mco_channel_t
 * in each channel descriptor.
 *
 * Returns the actual length of sent data or -1 if error.
 */
static int mco_nw_send(
                    nw_channel_h  ch,
                    const void*   buffer,
                    unsigned      buflen,
                    timer_unit    timeout
                    )
{
  MCO_RET ret;

  if (
      (ret=nw_send_message(ch, buffer, (int2)buflen, timeout)
      ) == MCO_S_OK 
     )
     return buflen;
  else return -1;
}

/******************************************************************************
 *
 *  Receive method of HA runtime.
 *
 * IN  nw_channel_h ch      - pointer to a channel descriptor.
 * OUT void *       buffer  - buffer for data to receive.
 * IN unsigned      buflen  - number of bytes to receive.
 * IN  timer_unit   timeout - wait-for-receive-completion timeout.
 *
 * Description:

 * This receive function is used implicitly by master-replica interconnection channel
 * mco_nw_recv MUST read exactly max_bytes !!!
 * The pointers to this function MUST be set to HA internal descriptor mco_channel_t
 * in each channel descriptor.
 *
 * Returns the actual length of sent data or -1 if error.
 */
static int mco_nw_recv(
                    nw_channel_h  ch,
                    const void*   buffer,
                    unsigned      buflen,
                    timer_unit    timeout
                    )
{
  MCO_RET ret;
  int2    len;

  if (
       (ret=nw_recv_message(
                            ch,
                            buffer,
                            (int2)buflen, 
                            &len,
                            timeout
       )
     ) == MCO_S_OK )
     return (int)len;
  else return -1;
}

/***************************************************************************
 *
 * HA error handler.
 *
 * IN ha_error_h  HAerror - pointer to ha_error_t structure described in mcoha.h.
 * The structure contains error code that caused the handler call & pointer to 
 * the descriptor of communication channel of the deleted replica. If the pointer not
 * equal to NULL then replica was deleted from master's list of replicas.
 *
 * Description:
 * HA error handler callback - closes replica channel & deallocates memory
 * used by it's descriptor
 */
static void  ErrorHandler( ha_error_h  HAerror)
{
  nw_channel_h ch = (nw_channel_h)HAerror->IOchannel;
  uint4        addr;

#ifdef  NW_DEBUG_OUTPUT
        Printf("Master: HA error handler called, errcode = %d\n", HAerror->errcode);
#endif

    if(ch != 0) {   // if (replica was deleted) {}
      addr = ntohl(ch->inaddr);
#ifdef  NW_DEBUG_OUTPUT
      Printf("Master: replica addr %s port %d\n",
        inet_ntoa(*((struct in_addr*)&addr)),
        ntohs(ch->sin.sin_port));
#endif

      nw_close((nw_channel_h)HAerror->IOchannel); // close communication channel
      free(HAerror->IOchannel);  // free the memory allocated by the descriptor
    }
}

/***************************************************************************
 *
 * Attaches replica to the master.
 *
 * IN	mco_db_h db       - database descriptor pointer.
 * IN	const char *      - devname.
 * IN   const mco_connection_param_t* params - connection & transaction timeouts.
 * IN	const char * replica_name - replica name (optional).
 * IN unsigned long timeout       - wait-for-connection timeout
 * IN OUT void * arg              - user defined argument. In this context
 * it is used as main/slave master flag in multimaster mode
 * (for shared memory only)
 *
 * Description:
 * This function includes connection algotrithm dependent on the type of a communication
 * channel. It attaches connected replica to HA subsystem.
 *
 * Returns MSO_S_OK if successful or error code (see above).
 */
MCO_RET mco_nw_attach_replica(
                        mco_db_h       db,
                        const char*    devname,
              		const          mco_connection_param_t * params,
             		const char*    replica_name,
              		timer_unit     timeout,
              		void *         arg)
{
  MCO_RET         ret;
  nw_channel_t    _ch;        // copy of IO channel in the stack
  nw_channel_h	  ch;         // pointer to the new IO channel
  ha_h            ha = (ha_h)arg;

/*
 * If the transport protocol isn't initialized  
 * then initialize it
 */
    if ( !(ha->baseChan.status&NWST_INITIALIZED) )  {
      ha->baseChan.db      = db;               // database handle. Is used by mco_nw_close()
      ha->baseChan.bufsize = sizeof(udp_msg_buf_t);
#ifdef NW_DEBUG_OUTPUT
      Printf( "\n  Initializing master communication channel's context, please wait...\n" );
#endif
      if( (ret = nw_init(&ha->baseChan)) != MCO_S_OK) {
#ifdef NW_DEBUG_OUTPUT
        Printf("Error initializing");

#endif
        return ret;
      }
    }

/* For POSIX/Linux only. WIN32 uses events. */
#ifndef _WIN32
   ha->baseChan.cancel_socket = INVALID_SOCKET_VALUE;
#endif //_WIN32

/*
 * If master's listener channel isn't initialized  
 * then open listener channel
 */
    if(!(ha->baseChan.status&NWST_LISTEN)) {
      if ( (ret=nw_listen(&ha->baseChan, devname)) != MCO_S_OK )
      {

#ifdef  NW_DEBUG_OUTPUT
        Printf("Error listening: %d\n", ret);
#endif
        return ret;
      }
#ifdef  NW_DEBUG_OUTPUT
      Printf("done\n");
#endif
    }
    ha->baseChan.db     = db;               // database handle. Is used by mco_nw_close()
    ha->baseChan.status |= NWST_IS_MASTER;  // ID_MASTER flag used by function mco_nw_close()
                                            // to check whether the transport layer still