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           case EINTR:
 116             {
 117               memcached_return rc;
 118
 119               rc= io_wait(ptr, MEM_READ);
 120
 121               if (rc == MEMCACHED_SUCCESS)
 122                 continue;
 123             }
 124           /* fall trough */
 125           default:
 126             {
 127               memcached_quit_server(ptr, 1);
 128               return -1;
 129             }
 130           }
 131         }
 132         else
 133         {
 134           found_eof= 1;
 135           break;
 136         }
 137       }
 138
 139       ptr->io_bytes_sent = 0;
 140       ptr->read_data_length= data_read;
 141       ptr->read_buffer_length= data_read;
 142       ptr->read_ptr= ptr->read_buffer;
 143     }
 144
 145     if (length > 1)
 146     {
 147       size_t difference;
 148
 149       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 150
 151       memcpy(buffer_ptr, ptr->read_ptr, difference);
 152       length -= difference;
 153       ptr->read_ptr+= difference;
 154       ptr->read_buffer_length-= difference;
 155       buffer_ptr+= difference;
 156     }
 157     else
 158     {
 159       *buffer_ptr= *ptr->read_ptr;
 160       ptr->read_ptr++;
 161       ptr->read_buffer_length--;
 162       buffer_ptr++;
 163       break;
 164     }
 165
 166     if (found_eof)
 167       break;
 168   }
 169
 170   return (size_t)(buffer_ptr - (char*)buffer);
 171 }
 172
 173 ssize_t memcached_io_write(memcached_server_st *ptr,
 174                            const void *buffer, size_t length, char with_flush)
 175 {
 176   size_t original_length;
 177   const char* buffer_ptr;
 178
 179   original_length= length;
 180   buffer_ptr= buffer;
 181
 182   while (length)
 183   {
 184     char *write_ptr;
 185     size_t should_write;
 186
 187     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 188     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 189
 190     should_write= (should_write < length) ? should_write : length;
 191
 192     memcpy(write_ptr, buffer_ptr, should_write);
 193     ptr->write_buffer_offset+= should_write;
 194     buffer_ptr+= should_write;
 195     length-= should_write;
 196
 197     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 198     {
 199       memcached_return rc;
 200       ssize_t sent_length;
 201
 202       sent_length= io_flush(ptr, &rc);
 203       if (sent_length == -1)
 204         return -1;
 205
 206       WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 207     }
 208   }
 209
 210   if (with_flush)
 211   {
 212     memcached_return rc;
 213     if (io_flush(ptr, &rc) == -1)
 214       return -1;
 215   }
 216
 217   return original_length;
 218 }
 219
 220 memcached_return memcached_io_close(memcached_server_st *ptr)
 221 {
 222   int r;
 223   /* in case of death shutdown to avoid blocking at close() */
 224
 225   r= shutdown(ptr->fd, SHUT_RDWR);
 226
 227 #ifdef HAVE_DEBUG
 228   if (r && errno != ENOTCONN)
 229   {
 230     WATCHPOINT_ERRNO(errno);
 231     WATCHPOINT_ASSERT(errno);
 232   }
 233 #endif
 234
 235   r= close(ptr->fd);
 236 #ifdef HAVE_DEBUG
 237   if (r != 0)
 238     WATCHPOINT_ERRNO(errno);
 239 #endif
 240
 241   return MEMCACHED_SUCCESS;
 242 }
 243
 244 static ssize_t io_flush(memcached_server_st *ptr,
 245                         memcached_return *error)
 246 {
 247   ssize_t sent_length;
 248   size_t return_length;
 249   char *local_write_ptr= ptr->write_buffer;
 250   size_t write_length= ptr->write_buffer_offset;
 251
 252   *error= MEMCACHED_SUCCESS;
 253
 254   if (ptr->write_buffer_offset == 0)
 255     return 0;
 256
 257   /* Looking for memory overflows */
 258 #if defined(HAVE_DEBUG)
 259   if (write_length == MEMCACHED_MAX_BUFFER)
 260     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 261   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 262 #endif
 263
 264   return_length= 0;
 265   while (write_length)
 266   {
 267     WATCHPOINT_ASSERT(write_length > 0);
 268     sent_length= 0;
 269     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 270     {
 271       struct addrinfo *ai;
 272
 273       ai= ptr->address_info;
 274
 275       /* Crappy test code */
 276       char buffer[HUGE_STRING_LEN + 8];
 277       memset(buffer, 0, HUGE_STRING_LEN + 8);
 278       memcpy (buffer+8, local_write_ptr, write_length);
 279       buffer[0]= 0;
 280       buffer[1]= 0;
 281       buffer[2]= 0;
 282       buffer[3]= 0;
 283       buffer[4]= 0;
 284       buffer[5]= 1;
 285       buffer[6]= 0;
 286       buffer[7]= 0;
 287       sent_length= sendto(ptr->fd, buffer, write_length + 8, 0,
 288                           (struct sockaddr *)ai->ai_addr,
 289                           ai->ai_addrlen);
 290       if (sent_length == -1)
 291       {
 292         WATCHPOINT_ERRNO(errno);
 293         WATCHPOINT_ASSERT(0);
 294       }
 295       sent_length-= 8; /* We remove the header */
 296     }
 297     else
 298     {
 299       /*
 300       ** We might want to purge the input buffer if we haven't consumed
 301       ** any output yet... The test for the limits is the purge is inline
 302       ** in the purge function to avoid duplicating the logic..
 303       */
 304       memcached_purge(ptr);
 305
 306       if ((sent_length= write(ptr->fd, local_write_ptr,
 307                                        write_length)) == -1)
 308       {
 309         switch (errno)
 310         {
 311         case ENOBUFS:
 312           continue;
 313         case EAGAIN:
 314           {
 315             memcached_return rc;
 316             rc= io_wait(ptr, MEM_WRITE);
 317
 318             if (rc == MEMCACHED_SUCCESS)
 319               continue;
 320
 321             memcached_quit_server(ptr, 1);
 322             return -1;
 323           }
 324         default:
 325           memcached_quit_server(ptr, 1);
 326           ptr->cached_errno= errno;
 327           *error= MEMCACHED_ERRNO;
 328           return -1;
 329         }
 330       }
 331     }
 332
 333     ptr->io_bytes_sent += sent_length;
 334
 335     local_write_ptr+= sent_length;
 336     write_length-= sent_length;
 337     return_length+= sent_length;
 338   }
 339
 340   WATCHPOINT_ASSERT(write_length == 0);
 341   // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
 342   // ptr->write_buffer_offset);
 343   ptr->write_buffer_offset= 0;
 344
 345   return return_length;
 346 }
 347
 348 /*
 349   Eventually we will just kill off the server with the problem.
 350 */
 351 void memcached_io_reset(memcached_server_st *ptr)
 352 {
 353   memcached_quit_server(ptr, 0);
 354 }