repsock.cpp

FastDb是高效的内存数据库系统

//-< REPSOCK.CPP >---------------------------------------------------*--------*
// FastDB                    Version 1.0         (c) 1999  GARRET    *     ?  *
// (Main Memory Database Management System)                          *   /\|  *
//                                                                   *  /  \  *
//                          Created:      3-May-2003  K.A. Knizhnik  * / [] \ *
//                          Last update:  6-May-2003  K.A. Knizhnik  * GARRET *
//-------------------------------------------------------------------*--------*
// Replication socket implementation
//-------------------------------------------------------------------*--------*

#define INSIDE_FASTDB

#include "repsock.h"
#include "sync.h"



void replication_socket_t::handleError(int socket, const char* operation, const char* error)
{
  fprintf(stderr, "Operation %s failed for socket %d: %s\n", operation, socket, error);
}

int replication_socket_t::read(void* buf, size_t min_size, size_t max_size, time_t timeout)
{
  dbSmallBuffer receiveBuf(min_size*n_sockets);
  int matches[MaxSockets];
  char* rcv = receiveBuf.base();
  int i, j, n = n_sockets;

  for (i = 0; i < n_sockets; i++)
  {
    matches[i] = -1;

    if (sockets[i] != NULL)
    {
      size_t received = 0;

      while (received < min_size)
      {
        int rc = sockets[i]->read(rcv + i*min_size + received, min_size - received, min_size - received, timeout);

        if (rc <= 0)
        {
          char msg[64];
          sockets[i]->get_error_text(msg, sizeof(msg));
          handleError(i, "read", msg);
          delete sockets[i];
          sockets[i] = NULL;
          break;
        }

        received += rc;
      }

      if (received == min_size)
      {
        matches[i] = 0;

        for (j = 0; j < i; j++)
        {
          if (matches[j] == 0)
          {
            if (memcmp(rcv + j*min_size, rcv + i*min_size, min_size) == 0)
            {
              matches[j] = i;
              break;
            }
          }
        }
      }
    }
  }

  int maxVotes = 0;
  int correctResponse = -1;

  for (i = 0; i < n; i++)
  {
    if (matches[i] >= 0)
    {
      int nVotes = 0;
      j = i;

      do
      {
        int next = matches[j];
        nVotes += 1;
        matches[j] = -1;
        j = next;
      }
      while (j != 0);

      if (nVotes > maxVotes)
      {
        maxVotes = nVotes;
        correctResponse = i;
      }
      else if (nVotes == maxVotes)
      {
        correctResponse = -1;
      }
    }
  }

  if (correctResponse >= 0)
  {
    succeed = true;
    memcpy(buf, rcv + correctResponse*min_size, min_size);
    return min_size;
  }
  else
  {
    handleError(-1, "read", "failed to choose correct response");
    succeed = false;
    return -1;
  }
}

bool replication_socket_t::write(void const* buf, size_t size)
{
  succeed = false;

  for (int i = n_sockets; --i >= 0;)
  {
    if (sockets[i] != NULL)
    {
      if (sockets[i]->write(buf, size))
      {
        succeed = true;
      }
      else
      {
        char msg[64];
        sockets[i]->get_error_text(msg, sizeof(msg));
        handleError(i, "write", msg);
        delete sockets[i];
        sockets[i] = NULL;
      }
    }
  }

  return succeed;
}

bool replication_socket_t::is_ok()
{
  return succeed;
}

void replication_socket_t::get_error_text(char* buf, size_t buf_size)
{
  strncpy(buf, succeed ? "ok" : "failed to select valid server", buf_size);
}

bool replication_socket_t::shutdown()
{
  succeed = false;

  for (int i = n_sockets; --i >= 0;)
  {
    if (sockets[i] != NULL)
    {
      if (sockets[i]->shutdown())
      {
        succeed = true;
      }
      else
      {
        char msg[64];
        sockets[i]->get_error_text(msg, sizeof(msg));
        handleError(i, "shutdown", msg);
        delete sockets[i];
        sockets[i] = NULL;
      }
    }
  }

  return succeed;
}

bool replication_socket_t::close()
{
  succeed = false;

  for (int i = n_sockets; --i >= 0;)
  {
    if (sockets[i] != NULL)
    {
      if (sockets[i]->close())
      {
        succeed = true;
      }
      else
      {
        char msg[64];
        sockets[i]->get_error_text(msg, sizeof(msg));
        handleError(i, "close", msg);
        delete sockets[i];
        sockets[i] = NULL;
      }
    }
  }

  return succeed;
}

replication_socket_t*  replication_socket_t::connect(char const* addresses[],
    int n_addresses,
    int max_attempts,
    time_t timeout)
{
  return new replication_socket_t(addresses, n_addresses, max_attempts, timeout);
}

int replication_socket_t::get_handle()
{
  return -1;
}

replication_socket_t::replication_socket_t(char const* addresses[], int n_addresses, int max_attempts, time_t timeout)
{
  n_sockets = n_addresses;
  assert(n_addresses < MaxSockets);
  sockets = new socket_t*[n_addresses];

  for (int i = n_addresses; --i >= 0;)
  {
    socket_t* s = socket_t::connect(addresses[i], socket_t::sock_global_domain, max_attempts, timeout);

    if (s != NULL)
    {
      if (s->is_ok())
      {
        succeed = true;
      }
      else
      {
        char msg[64];
        s->get_error_text(msg, sizeof(msg));
        handleError(i, "connect", msg);
        delete s;
        s = NULL;
      }
    }
    else
    {
      handleError(i, "connect", "failed to create socket");
    }

    sockets[i] = s;
  }
}

socket_t* replication_socket_t::accept()
{
  return NULL;
}

bool replication_socket_t::cancel_accept()
{
  return false;
}

char* replication_socket_t::get_peer_name()
{
  return NULL;
}

replication_socket_t::~replication_socket_t()
{
  if (sockets != NULL)
  {
    for (int i = n_sockets; --i >= 0;)
    {
      delete sockets[i];
    }
  }

  delete[] sockets;
}