git.m6w6.name Git - m6w6/libmemcached/blob - lib/memcached_io.c

   1 /*
   2   Basic socket buffered IO
   3 */
   4
   5 #include "common.h"
   6 #include "memcached_io.h"
   7 #include <sys/select.h>
   8 #include <poll.h>
   9
  10 typedef enum {
  11   MEM_READ,
  12   MEM_WRITE,
  13 } memc_read_or_write;
  14
  15 static ssize_t io_flush(memcached_server_st *ptr, memcached_return *error);
  16
  17 static memcached_return io_wait(memcached_server_st *ptr,
  18                                 memc_read_or_write read_or_write)
  19 {
  20   struct pollfd fds[1];
  21   short flags= 0;
  22   int error;
  23
  24   if (read_or_write == MEM_WRITE) /* write */
  25     flags= POLLOUT |  POLLERR;
  26   else
  27     flags= POLLIN | POLLERR;
  28
  29   memset(&fds, 0, sizeof(struct pollfd));
  30   fds[0].fd= ptr->fd;
  31   fds[0].events= flags;
  32
  33   error= poll(fds, 1, ptr->root->poll_timeout);
  34
  35   if (error == 1)
  36     return MEMCACHED_SUCCESS;
  37   else if (error == 0)
  38   {
  39     return MEMCACHED_TIMEOUT;
  40   }
  41
  42   /* Imposssible for anything other then -1 */
  43   WATCHPOINT_ASSERT(error == -1);
  44   memcached_quit_server(ptr, 1);
  45
  46   return MEMCACHED_FAILURE;
  47
  48 }
  49
  50 #ifdef UNUSED
  51 void memcached_io_preread(memcached_st *ptr)
  52 {
  53   unsigned int x;
  54
  55   return;
  56
  57   for (x= 0; x < ptr->number_of_hosts; x++)
  58   {
  59     if (memcached_server_response_count(ptr, x) &&
  60         ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
  61     {
  62       size_t data_read;
  63
  64       data_read= read(ptr->hosts[x].fd,
  65                       ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
  66                       MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length);
  67       if (data_read == -1)
  68         continue;
  69
  70       ptr->hosts[x].read_buffer_length+= data_read;
  71       ptr->hosts[x].read_data_length+= data_read;
  72     }
  73   }
  74 }
  75 #endif
  76
  77 ssize_t memcached_io_read(memcached_server_st *ptr,
  78                           char *buffer, size_t length)
  79 {
  80   char *buffer_ptr;
  81
  82   buffer_ptr= buffer;
  83
  84   while (length)
  85   {
  86     uint8_t found_eof= 0;
  87     if (!ptr->read_buffer_length)
  88     {
  89       ssize_t data_read;
  90
  91       while (1)
  92       {
  93         data_read= read(ptr->fd,
  94                         ptr->read_buffer,
  95                         MEMCACHED_MAX_BUFFER);
  96         if (data_read > 0)
  97           break;
  98         else if (data_read == -1)
  99         {
 100           ptr->cached_errno= errno;
 101           switch (errno)
 102           {
 103           case EAGAIN:
 104             {
 105               memcached_return rc;
 106
 107               rc= io_wait(ptr, MEM_READ);
 108
 109               if (rc == MEMCACHED_SUCCESS)
 110                 continue;
 111             }
 112           /* fall trough */
 113           default:
 114             {
 115               memcached_quit_server(ptr, 1);
 116               return -1;
 117             }
 118           }
 119         }
 120         else
 121         {
 122           WATCHPOINT_ASSERT(0);
 123           found_eof= 1;
 124           break;
 125         }
 126       }
 127
 128       ptr->read_data_length= data_read;
 129       ptr->read_buffer_length= data_read;
 130       ptr->read_ptr= ptr->read_buffer;
 131     }
 132
 133     if (length > 1)
 134     {
 135       size_t difference;
 136
 137       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 138
 139       memcpy(buffer_ptr, ptr->read_ptr, difference);
 140       length -= difference;
 141       ptr->read_ptr+= difference;
 142       ptr->read_buffer_length-= difference;
 143       buffer_ptr+= difference;
 144     }
 145     else
 146     {
 147       *buffer_ptr= *ptr->read_ptr;
 148       ptr->read_ptr++;
 149       ptr->read_buffer_length--;
 150       buffer_ptr++;
 151       break;
 152     }
 153
 154     if (found_eof)
 155       break;
 156   }
 157
 158   return (size_t)(buffer_ptr - buffer);
 159 }
 160
 161 ssize_t memcached_io_write(memcached_server_st *ptr,
 162                            char *buffer, size_t length, char with_flush)
 163 {
 164   size_t original_length;
 165   char* buffer_ptr;
 166
 167   original_length= length;
 168   buffer_ptr= buffer;
 169
 170   while (length)
 171   {
 172     char *write_ptr;
 173     size_t should_write;
 174
 175     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 176     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 177
 178     should_write= (should_write < length) ? should_write : length;
 179
 180     memcpy(write_ptr, buffer_ptr, should_write);
 181     ptr->write_buffer_offset+= should_write;
 182     buffer_ptr+= should_write;
 183     length-= should_write;
 184
 185     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 186     {
 187       memcached_return rc;
 188       ssize_t sent_length;
 189
 190       sent_length= io_flush(ptr, &rc);
 191       if (sent_length == -1)
 192         return -1;
 193
 194       WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 195     }
 196   }
 197
 198   if (with_flush)
 199   {
 200     memcached_return rc;
 201     if (io_flush(ptr, &rc) == -1)
 202       return -1;
 203   }
 204
 205   return original_length;
 206 }
 207
 208 memcached_return memcached_io_close(memcached_server_st *ptr)
 209 {
 210   close(ptr->fd);
 211
 212   return MEMCACHED_SUCCESS;
 213 }
 214
 215 static ssize_t io_flush(memcached_server_st *ptr,
 216                                   memcached_return *error)
 217 {
 218   size_t sent_length;
 219   size_t return_length;
 220   char *local_write_ptr= ptr->write_buffer;
 221   size_t write_length= ptr->write_buffer_offset;
 222
 223   *error= MEMCACHED_SUCCESS;
 224
 225   if (ptr->write_buffer_offset == 0)
 226     return 0;
 227
 228   /* Looking for memory overflows */
 229   if (write_length == MEMCACHED_MAX_BUFFER)
 230     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 231   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 232   return_length= 0;
 233   while (write_length)
 234   {
 235     sent_length= 0;
 236     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 237     {
 238       sent_length= sendto(ptr->fd, local_write_ptr, write_length, 0,
 239                           (struct sockaddr *)&ptr->address_info->ai_addr,
 240                           sizeof(struct sockaddr));
 241     }
 242     else
 243     {
 244       if ((ssize_t)(sent_length= write(ptr->fd, local_write_ptr,
 245                                        write_length)) == -1)
 246       {
 247         switch (errno)
 248         {
 249         case ENOBUFS:
 250           continue;
 251         case EAGAIN:
 252           {
 253             memcached_return rc;
 254             rc= io_wait(ptr, MEM_WRITE);
 255
 256             if (rc == MEMCACHED_SUCCESS)
 257               continue;
 258
 259             memcached_quit_server(ptr, 1);
 260             return -1;
 261           }
 262         default:
 263           memcached_quit_server(ptr, 1);
 264           ptr->cached_errno= errno;
 265           *error= MEMCACHED_ERRNO;
 266           return -1;
 267         }
 268       }
 269     }
 270
 271     local_write_ptr+= sent_length;
 272     write_length-= sent_length;
 273     return_length+= sent_length;
 274   }
 275
 276   WATCHPOINT_ASSERT(write_length == 0);
 277   WATCHPOINT_ASSERT(return_length == ptr->write_buffer_offset);
 278   ptr->write_buffer_offset= 0;
 279
 280   return return_length;
 281 }
 282
 283 /*
 284   Eventually we will just kill off the server with the problem.
 285 */
 286 void memcached_io_reset(memcached_server_st *ptr)
 287 {
 288   ptr->write_buffer_offset= 0;
 289   memcached_quit_server(ptr, 0);
 290 }