git.m6w6.name Git - awesomized/libmemcached/blob - libmemcached/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   /*
  34   ** We are going to block on write, but at least on Solaris we might block
  35   ** on write if we haven't read anything from our input buffer..
  36   ** Try to purge the input buffer if we don't do any flow control in the
  37   ** application layer (just sending a lot of data etc)
  38   ** The test is moved down in the purge function to avoid duplication of
  39   ** the test.
  40   */
  41   if (read_or_write == MEM_WRITE)
  42     memcached_purge(ptr);
  43
  44   error= poll(fds, 1, ptr->root->poll_timeout);
  45
  46   if (error == 1)
  47     return MEMCACHED_SUCCESS;
  48   else if (error == 0)
  49   {
  50     return MEMCACHED_TIMEOUT;
  51   }
  52
  53   /* Imposssible for anything other then -1 */
  54   WATCHPOINT_ASSERT(error == -1);
  55   memcached_quit_server(ptr, 1);
  56
  57   return MEMCACHED_FAILURE;
  58
  59 }
  60
  61 #ifdef UNUSED
  62 void memcached_io_preread(memcached_st *ptr)
  63 {
  64   unsigned int x;
  65
  66   return;
  67
  68   for (x= 0; x < ptr->number_of_hosts; x++)
  69   {
  70     if (memcached_server_response_count(ptr, x) &&
  71         ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
  72     {
  73       size_t data_read;
  74
  75       data_read= read(ptr->hosts[x].fd,
  76                       ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
  77                       MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length);
  78       if (data_read == -1)
  79         continue;
  80
  81       ptr->hosts[x].read_buffer_length+= data_read;
  82       ptr->hosts[x].read_data_length+= data_read;
  83     }
  84   }
  85 }
  86 #endif
  87
  88 ssize_t memcached_io_read(memcached_server_st *ptr,
  89                           void *buffer, size_t length)
  90 {
  91   char *buffer_ptr;
  92
  93   buffer_ptr= buffer;
  94
  95   while (length)
  96   {
  97     uint8_t found_eof= 0;
  98     if (!ptr->read_buffer_length)
  99     {
 100       ssize_t data_read;
 101
 102       while (1)
 103       {
 104         data_read= read(ptr->fd,
 105                         ptr->read_buffer,
 106                         MEMCACHED_MAX_BUFFER);
 107         if (data_read > 0)
 108           break;
 109         else if (data_read == -1)
 110         {
 111           ptr->cached_errno= errno;
 112           switch (errno)
 113           {
 114           case EAGAIN:
 115             {
 116               memcached_return rc;
 117
 118               rc= io_wait(ptr, MEM_READ);
 119
 120               if (rc == MEMCACHED_SUCCESS)
 121                 continue;
 122             }
 123           /* fall trough */
 124           default:
 125             {
 126               memcached_quit_server(ptr, 1);
 127               return -1;
 128             }
 129           }
 130         }
 131         else
 132         {
 133           found_eof= 1;
 134           break;
 135         }
 136       }
 137
 138       ptr->io_bytes_sent = 0;
 139       ptr->read_data_length= data_read;
 140       ptr->read_buffer_length= data_read;
 141       ptr->read_ptr= ptr->read_buffer;
 142     }
 143
 144     if (length > 1)
 145     {
 146       size_t difference;
 147
 148       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 149
 150       memcpy(buffer_ptr, ptr->read_ptr, difference);
 151       length -= difference;
 152       ptr->read_ptr+= difference;
 153       ptr->read_buffer_length-= difference;
 154       buffer_ptr+= difference;
 155     }
 156     else
 157     {
 158       *buffer_ptr= *ptr->read_ptr;
 159       ptr->read_ptr++;
 160       ptr->read_buffer_length--;
 161       buffer_ptr++;
 162       break;
 163     }
 164
 165     if (found_eof)
 166       break;
 167   }
 168
 169   return (size_t)(buffer_ptr - (char*)buffer);
 170 }
 171
 172 ssize_t memcached_io_write(memcached_server_st *ptr,
 173                            const void *buffer, size_t length, char with_flush)
 174 {
 175   size_t original_length;
 176   const char* buffer_ptr;
 177
 178   original_length= length;
 179   buffer_ptr= buffer;
 180
 181   while (length)
 182   {
 183     char *write_ptr;
 184     size_t should_write;
 185
 186     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 187     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 188
 189     should_write= (should_write < length) ? should_write : length;
 190
 191     memcpy(write_ptr, buffer_ptr, should_write);
 192     ptr->write_buffer_offset+= should_write;
 193     buffer_ptr+= should_write;
 194     length-= should_write;
 195
 196     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 197     {
 198       memcached_return rc;
 199       ssize_t sent_length;
 200
 201       sent_length= io_flush(ptr, &rc);
 202       if (sent_length == -1)
 203         return -1;
 204
 205       WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 206     }
 207   }
 208
 209   if (with_flush)
 210   {
 211     memcached_return rc;
 212     if (io_flush(ptr, &rc) == -1)
 213       return -1;
 214   }
 215
 216   return original_length;
 217 }
 218
 219 memcached_return memcached_io_close(memcached_server_st *ptr)
 220 {
 221   int r;
 222   /* in case of death shutdown to avoid blocking at close() */
 223
 224   r= shutdown(ptr->fd, SHUT_RDWR);
 225
 226 #ifdef HAVE_DEBUG
 227   if (r && errno != ENOTCONN)
 228   {
 229     WATCHPOINT_ERRNO(errno);
 230     WATCHPOINT_ASSERT(errno);
 231   }
 232 #endif
 233
 234   r= close(ptr->fd);
 235 #ifdef HAVE_DEBUG
 236   if (r != 0)
 237     WATCHPOINT_ERRNO(errno);
 238 #endif
 239
 240   return MEMCACHED_SUCCESS;
 241 }
 242
 243 static ssize_t io_flush(memcached_server_st *ptr,
 244                         memcached_return *error)
 245 {
 246   ssize_t sent_length;
 247   size_t return_length;
 248   char *local_write_ptr= ptr->write_buffer;
 249   size_t write_length= ptr->write_buffer_offset;
 250
 251   *error= MEMCACHED_SUCCESS;
 252
 253   if (ptr->write_buffer_offset == 0)
 254     return 0;
 255
 256   /* Looking for memory overflows */
 257 #if defined(HAVE_DEBUG)
 258   if (write_length == MEMCACHED_MAX_BUFFER)
 259     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 260   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 261 #endif
 262
 263   return_length= 0;
 264   while (write_length)
 265   {
 266     WATCHPOINT_ASSERT(write_length > 0);
 267     sent_length= 0;
 268     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 269     {
 270       struct addrinfo *ai;
 271
 272       ai= ptr->address_info;
 273
 274       /* Crappy test code */
 275       char buffer[HUGE_STRING_LEN + 8];
 276       memset(buffer, 0, HUGE_STRING_LEN + 8);
 277       memcpy (buffer+8, local_write_ptr, write_length);
 278       buffer[0]= 0;
 279       buffer[1]= 0;
 280       buffer[2]= 0;
 281       buffer[3]= 0;
 282       buffer[4]= 0;
 283       buffer[5]= 1;
 284       buffer[6]= 0;
 285       buffer[7]= 0;
 286       sent_length= sendto(ptr->fd, buffer, write_length + 8, 0,
 287                           (struct sockaddr *)ai->ai_addr,
 288                           ai->ai_addrlen);
 289       if (sent_length == -1)
 290       {
 291         WATCHPOINT_ERRNO(errno);
 292         WATCHPOINT_ASSERT(0);
 293       }
 294       sent_length-= 8; /* We remove the header */
 295     }
 296     else
 297     {
 298       /*
 299       ** We might want to purge the input buffer if we haven't consumed
 300       ** any output yet... The test for the limits is the purge is inline
 301       ** in the purge function to avoid duplicating the logic..
 302       */
 303       memcached_purge(ptr);
 304
 305       if ((sent_length= write(ptr->fd, local_write_ptr,
 306                                        write_length)) == -1)
 307       {
 308         switch (errno)
 309         {
 310         case ENOBUFS:
 311           continue;
 312         case EAGAIN:
 313           {
 314             memcached_return rc;
 315             rc= io_wait(ptr, MEM_WRITE);
 316
 317             if (rc == MEMCACHED_SUCCESS)
 318               continue;
 319
 320             memcached_quit_server(ptr, 1);
 321             return -1;
 322           }
 323         default:
 324           memcached_quit_server(ptr, 1);
 325           ptr->cached_errno= errno;
 326           *error= MEMCACHED_ERRNO;
 327           return -1;
 328         }
 329       }
 330     }
 331
 332     ptr->io_bytes_sent += sent_length;
 333
 334     local_write_ptr+= sent_length;
 335     write_length-= sent_length;
 336     return_length+= sent_length;
 337   }
 338
 339   WATCHPOINT_ASSERT(write_length == 0);
 340   // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
 341   // ptr->write_buffer_offset);
 342   ptr->write_buffer_offset= 0;
 343
 344   return return_length;
 345 }
 346
 347 /*
 348   Eventually we will just kill off the server with the problem.
 349 */
 350 void memcached_io_reset(memcached_server_st *ptr)
 351 {
 352   memcached_quit_server(ptr, 0);
 353 }