git.m6w6.name Git - m6w6/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 #ifdef NOT_DONE
  34   /*
  35   ** We are going to block on write, but at least on Solaris we might block
  36   ** on write if we haven't read anything from our input buffer..
  37   ** Try to purge the input buffer if we don't do any flow control in the
  38   ** application layer (just sending a lot of data etc)
  39   ** The test is moved down in the purge function to avoid duplication of
  40   ** the test.
  41   */
  42   if (read_or_write == MEM_WRITE)
  43   {
  44     if (memcached_purge(ptr) != MEMCACHED_SUCCESS || memcached_purge(ptr) != MEMCACHED_STORED)
  45       return MEMCACHED_FAILURE;
  46   }
  47 #endif
  48
  49   error= poll(fds, 1, ptr->root->poll_timeout);
  50
  51   if (error == 1)
  52     return MEMCACHED_SUCCESS;
  53   else if (error == 0)
  54   {
  55     return MEMCACHED_TIMEOUT;
  56   }
  57
  58   /* Imposssible for anything other then -1 */
  59   WATCHPOINT_ASSERT(error == -1);
  60   memcached_quit_server(ptr, 1);
  61
  62   return MEMCACHED_FAILURE;
  63
  64 }
  65
  66 #ifdef UNUSED
  67 void memcached_io_preread(memcached_st *ptr)
  68 {
  69   unsigned int x;
  70
  71   return;
  72
  73   for (x= 0; x < ptr->number_of_hosts; x++)
  74   {
  75     if (memcached_server_response_count(ptr, x) &&
  76         ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
  77     {
  78       size_t data_read;
  79
  80       data_read= read(ptr->hosts[x].fd,
  81                       ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
  82                       MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length);
  83       if (data_read == -1)
  84         continue;
  85
  86       ptr->hosts[x].read_buffer_length+= data_read;
  87       ptr->hosts[x].read_data_length+= data_read;
  88     }
  89   }
  90 }
  91 #endif
  92
  93 ssize_t memcached_io_read(memcached_server_st *ptr,
  94                           void *buffer, size_t length)
  95 {
  96   char *buffer_ptr;
  97
  98   buffer_ptr= buffer;
  99
 100   while (length)
 101   {
 102     uint8_t found_eof= 0;
 103     if (!ptr->read_buffer_length)
 104     {
 105       ssize_t data_read;
 106
 107       while (1)
 108       {
 109         data_read= read(ptr->fd,
 110                         ptr->read_buffer,
 111                         MEMCACHED_MAX_BUFFER);
 112         if (data_read > 0)
 113           break;
 114         else if (data_read == -1)
 115         {
 116           ptr->cached_errno= errno;
 117           switch (errno)
 118           {
 119           case EAGAIN:
 120           case EINTR:
 121             {
 122               memcached_return rc;
 123
 124               rc= io_wait(ptr, MEM_READ);
 125
 126               if (rc == MEMCACHED_SUCCESS)
 127                 continue;
 128             }
 129           /* fall trough */
 130           default:
 131             {
 132               memcached_quit_server(ptr, 1);
 133               return -1;
 134             }
 135           }
 136         }
 137         else
 138         {
 139           found_eof= 1;
 140           break;
 141         }
 142       }
 143
 144       ptr->io_bytes_sent = 0;
 145       ptr->read_data_length= data_read;
 146       ptr->read_buffer_length= data_read;
 147       ptr->read_ptr= ptr->read_buffer;
 148     }
 149
 150     if (length > 1)
 151     {
 152       size_t difference;
 153
 154       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 155
 156       memcpy(buffer_ptr, ptr->read_ptr, difference);
 157       length -= difference;
 158       ptr->read_ptr+= difference;
 159       ptr->read_buffer_length-= difference;
 160       buffer_ptr+= difference;
 161     }
 162     else
 163     {
 164       *buffer_ptr= *ptr->read_ptr;
 165       ptr->read_ptr++;
 166       ptr->read_buffer_length--;
 167       buffer_ptr++;
 168       break;
 169     }
 170
 171     if (found_eof)
 172       break;
 173   }
 174
 175   return (size_t)(buffer_ptr - (char*)buffer);
 176 }
 177
 178 ssize_t memcached_io_write(memcached_server_st *ptr,
 179                            const void *buffer, size_t length, char with_flush)
 180 {
 181   size_t original_length;
 182   const char* buffer_ptr;
 183
 184   WATCHPOINT_ASSERT(ptr->fd != -1);
 185
 186   original_length= length;
 187   buffer_ptr= buffer;
 188
 189   while (length)
 190   {
 191     char *write_ptr;
 192     size_t should_write;
 193
 194     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 195     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 196
 197     should_write= (should_write < length) ? should_write : length;
 198
 199     memcpy(write_ptr, buffer_ptr, should_write);
 200     ptr->write_buffer_offset+= should_write;
 201     buffer_ptr+= should_write;
 202     length-= should_write;
 203
 204     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 205     {
 206       memcached_return rc;
 207       ssize_t sent_length;
 208
 209       WATCHPOINT_ASSERT(ptr->fd != -1);
 210       sent_length= io_flush(ptr, &rc);
 211       if (sent_length == -1)
 212         return -1;
 213
 214       WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 215     }
 216   }
 217
 218   if (with_flush)
 219   {
 220     memcached_return rc;
 221     WATCHPOINT_ASSERT(ptr->fd != -1);
 222     if (io_flush(ptr, &rc) == -1)
 223       return -1;
 224   }
 225
 226   return original_length;
 227 }
 228
 229 memcached_return memcached_io_close(memcached_server_st *ptr)
 230 {
 231   int r;
 232
 233   if (ptr->fd == -1)
 234     return MEMCACHED_SUCCESS;
 235
 236   /* in case of death shutdown to avoid blocking at close() */
 237   r= shutdown(ptr->fd, SHUT_RDWR);
 238
 239 #ifdef HAVE_DEBUG
 240   if (r && errno != ENOTCONN)
 241   {
 242     WATCHPOINT_NUMBER(ptr->fd);
 243     WATCHPOINT_ERRNO(errno);
 244     WATCHPOINT_ASSERT(errno);
 245   }
 246 #endif
 247
 248   r= close(ptr->fd);
 249 #ifdef HAVE_DEBUG
 250   if (r != 0)
 251     WATCHPOINT_ERRNO(errno);
 252 #endif
 253
 254   return MEMCACHED_SUCCESS;
 255 }
 256
 257 static ssize_t io_flush(memcached_server_st *ptr,
 258                         memcached_return *error)
 259 {
 260   ssize_t sent_length;
 261   size_t return_length;
 262   char *local_write_ptr= ptr->write_buffer;
 263   size_t write_length= ptr->write_buffer_offset;
 264
 265   *error= MEMCACHED_SUCCESS;
 266
 267   WATCHPOINT_ASSERT(ptr->fd != -1);
 268
 269   if (ptr->write_buffer_offset == 0)
 270     return 0;
 271
 272   /* Looking for memory overflows */
 273 #if defined(HAVE_DEBUG)
 274   if (write_length == MEMCACHED_MAX_BUFFER)
 275     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 276   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 277 #endif
 278
 279   return_length= 0;
 280   while (write_length)
 281   {
 282     WATCHPOINT_ASSERT(ptr->fd != -1);
 283     WATCHPOINT_ASSERT(write_length > 0);
 284     sent_length= 0;
 285     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 286     {
 287       struct addrinfo *ai;
 288
 289       ai= ptr->address_info;
 290
 291       /* Crappy test code */
 292       char buffer[HUGE_STRING_LEN + 8];
 293       memset(buffer, 0, HUGE_STRING_LEN + 8);
 294       memcpy (buffer+8, local_write_ptr, write_length);
 295       buffer[0]= 0;
 296       buffer[1]= 0;
 297       buffer[2]= 0;
 298       buffer[3]= 0;
 299       buffer[4]= 0;
 300       buffer[5]= 1;
 301       buffer[6]= 0;
 302       buffer[7]= 0;
 303       sent_length= sendto(ptr->fd, buffer, write_length + 8, 0,
 304                           (struct sockaddr *)ai->ai_addr,
 305                           ai->ai_addrlen);
 306       if (sent_length == -1)
 307       {
 308         WATCHPOINT_ERRNO(errno);
 309         WATCHPOINT_ASSERT(0);
 310       }
 311       sent_length-= 8; /* We remove the header */
 312     }
 313     else
 314     {
 315 #ifdef NOT_DONE
 316       /*
 317       ** We might want to purge the input buffer if we haven't consumed
 318       ** any output yet... The test for the limits is the purge is inline
 319       ** in the purge function to avoid duplicating the logic..
 320       */
 321       {
 322         memcached_return rc;
 323         WATCHPOINT_ASSERT(ptr->fd != -1);
 324         rc= memcached_purge(ptr);
 325
 326         if (rc != MEMCACHED_SUCCESS || rc != MEMCACHED_STORED)
 327           return -1;
 328       }
 329 #endif
 330
 331       WATCHPOINT_ASSERT(ptr->fd != -1);
 332       if ((sent_length= write(ptr->fd, local_write_ptr,
 333                               write_length)) == -1)
 334       {
 335         switch (errno)
 336         {
 337         case ENOBUFS:
 338           continue;
 339         case EAGAIN:
 340           {
 341             memcached_return rc;
 342             rc= io_wait(ptr, MEM_WRITE);
 343
 344             if (rc == MEMCACHED_SUCCESS)
 345               continue;
 346
 347             memcached_quit_server(ptr, 1);
 348             return -1;
 349           }
 350         default:
 351           memcached_quit_server(ptr, 1);
 352           ptr->cached_errno= errno;
 353           *error= MEMCACHED_ERRNO;
 354           return -1;
 355         }
 356       }
 357     }
 358
 359     ptr->io_bytes_sent += sent_length;
 360
 361     local_write_ptr+= sent_length;
 362     write_length-= sent_length;
 363     return_length+= sent_length;
 364   }
 365
 366   WATCHPOINT_ASSERT(write_length == 0);
 367   // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
 368   // ptr->write_buffer_offset);
 369   ptr->write_buffer_offset= 0;
 370
 371   return return_length;
 372 }
 373
 374 /*
 375   Eventually we will just kill off the server with the problem.
 376 */
 377 void memcached_io_reset(memcached_server_st *ptr)
 378 {
 379   memcached_quit_server(ptr, 0);
 380 }