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 #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     if (!ptr->read_buffer_length)
 103     {
 104       ssize_t data_read;
 105
 106       while (1)
 107       {
 108         data_read= read(ptr->fd,
 109                         ptr->read_buffer,
 110                         MEMCACHED_MAX_BUFFER);
 111         if (data_read > 0)
 112           break;
 113         else if (data_read == -1)
 114         {
 115           ptr->cached_errno= errno;
 116           switch (errno)
 117           {
 118           case EAGAIN:
 119           case EINTR:
 120             {
 121               memcached_return rc;
 122
 123               rc= io_wait(ptr, MEM_READ);
 124
 125               if (rc == MEMCACHED_SUCCESS)
 126                 continue;
 127             }
 128           /* fall trough */
 129           default:
 130             {
 131               memcached_quit_server(ptr, 1);
 132               return -1;
 133             }
 134           }
 135         }
 136         else
 137         {
 138           /*
 139             EOF. Any data received so far is incomplete
 140             so discard it. This always reads by byte in case of TCP
 141             and protocol enforcement happens at memcached_response()
 142             looking for '\n'. We do not care for UDB which requests 8 bytes
 143             at once. Generally, this means that connection went away. Since
 144             for blocking I/O we do not return 0 and for non-blocking case
 145             it will return EGAIN if data is not immediatly available.
 146           */
 147           memcached_quit_server(ptr, 1);
 148           return -1;
 149         }
 150       }
 151
 152       ptr->io_bytes_sent = 0;
 153       ptr->read_data_length= data_read;
 154       ptr->read_buffer_length= data_read;
 155       ptr->read_ptr= ptr->read_buffer;
 156     }
 157
 158     if (length > 1)
 159     {
 160       size_t difference;
 161
 162       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 163
 164       memcpy(buffer_ptr, ptr->read_ptr, difference);
 165       length -= difference;
 166       ptr->read_ptr+= difference;
 167       ptr->read_buffer_length-= difference;
 168       buffer_ptr+= difference;
 169     }
 170     else
 171     {
 172       *buffer_ptr= *ptr->read_ptr;
 173       ptr->read_ptr++;
 174       ptr->read_buffer_length--;
 175       buffer_ptr++;
 176       break;
 177     }
 178   }
 179
 180   return (size_t)(buffer_ptr - (char*)buffer);
 181 }
 182
 183 ssize_t memcached_io_write(memcached_server_st *ptr,
 184                            const void *buffer, size_t length, char with_flush)
 185 {
 186   size_t original_length;
 187   const char* buffer_ptr;
 188
 189   WATCHPOINT_ASSERT(ptr->fd != -1);
 190
 191   original_length= length;
 192   buffer_ptr= buffer;
 193
 194   while (length)
 195   {
 196     char *write_ptr;
 197     size_t should_write;
 198
 199     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 200     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 201
 202     should_write= (should_write < length) ? should_write : length;
 203
 204     memcpy(write_ptr, buffer_ptr, should_write);
 205     ptr->write_buffer_offset+= should_write;
 206     buffer_ptr+= should_write;
 207     length-= should_write;
 208
 209     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 210     {
 211       memcached_return rc;
 212       ssize_t sent_length;
 213
 214       WATCHPOINT_ASSERT(ptr->fd != -1);
 215       sent_length= io_flush(ptr, &rc);
 216       if (sent_length == -1)
 217         return -1;
 218
 219       WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 220     }
 221   }
 222
 223   if (with_flush)
 224   {
 225     memcached_return rc;
 226     WATCHPOINT_ASSERT(ptr->fd != -1);
 227     if (io_flush(ptr, &rc) == -1)
 228       return -1;
 229   }
 230
 231   return original_length;
 232 }
 233
 234 memcached_return memcached_io_close(memcached_server_st *ptr)
 235 {
 236   int r;
 237
 238   if (ptr->fd == -1)
 239     return MEMCACHED_SUCCESS;
 240
 241   /* in case of death shutdown to avoid blocking at close() */
 242   if (1)
 243   {
 244     r= shutdown(ptr->fd, SHUT_RDWR);
 245
 246 #ifdef HAVE_DEBUG
 247     if (r && errno != ENOTCONN)
 248     {
 249       WATCHPOINT_NUMBER(ptr->fd);
 250       WATCHPOINT_ERRNO(errno);
 251       WATCHPOINT_ASSERT(errno);
 252     }
 253 #endif
 254   }
 255
 256   r= close(ptr->fd);
 257 #ifdef HAVE_DEBUG
 258   if (r != 0)
 259     WATCHPOINT_ERRNO(errno);
 260 #endif
 261
 262   return MEMCACHED_SUCCESS;
 263 }
 264
 265 static ssize_t io_flush(memcached_server_st *ptr,
 266                         memcached_return *error)
 267 {
 268   ssize_t sent_length;
 269   size_t return_length;
 270   char *local_write_ptr= ptr->write_buffer;
 271   size_t write_length= ptr->write_buffer_offset;
 272
 273   *error= MEMCACHED_SUCCESS;
 274
 275   WATCHPOINT_ASSERT(ptr->fd != -1);
 276
 277   if (ptr->write_buffer_offset == 0)
 278     return 0;
 279
 280   /* Looking for memory overflows */
 281 #if defined(HAVE_DEBUG)
 282   if (write_length == MEMCACHED_MAX_BUFFER)
 283     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 284   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 285 #endif
 286
 287   return_length= 0;
 288   while (write_length)
 289   {
 290     WATCHPOINT_ASSERT(ptr->fd != -1);
 291     WATCHPOINT_ASSERT(write_length > 0);
 292     sent_length= 0;
 293     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 294     {
 295       struct addrinfo *ai;
 296
 297       ai= ptr->address_info;
 298
 299       /* Crappy test code */
 300       char buffer[HUGE_STRING_LEN + 8];
 301       memset(buffer, 0, HUGE_STRING_LEN + 8);
 302       memcpy (buffer+8, local_write_ptr, write_length);
 303       buffer[0]= 0;
 304       buffer[1]= 0;
 305       buffer[2]= 0;
 306       buffer[3]= 0;
 307       buffer[4]= 0;
 308       buffer[5]= 1;
 309       buffer[6]= 0;
 310       buffer[7]= 0;
 311       sent_length= sendto(ptr->fd, buffer, write_length + 8, 0,
 312                           (struct sockaddr *)ai->ai_addr,
 313                           ai->ai_addrlen);
 314       if (sent_length == -1)
 315       {
 316         WATCHPOINT_ERRNO(errno);
 317         WATCHPOINT_ASSERT(0);
 318       }
 319       sent_length-= 8; /* We remove the header */
 320     }
 321     else
 322     {
 323 #ifdef NOT_DONE
 324       /*
 325       ** We might want to purge the input buffer if we haven't consumed
 326       ** any output yet... The test for the limits is the purge is inline
 327       ** in the purge function to avoid duplicating the logic..
 328       */
 329       {
 330         memcached_return rc;
 331         WATCHPOINT_ASSERT(ptr->fd != -1);
 332         rc= memcached_purge(ptr);
 333
 334         if (rc != MEMCACHED_SUCCESS || rc != MEMCACHED_STORED)
 335           return -1;
 336       }
 337 #endif
 338
 339       WATCHPOINT_ASSERT(ptr->fd != -1);
 340       if ((sent_length= write(ptr->fd, local_write_ptr,
 341                               write_length)) == -1)
 342       {
 343         switch (errno)
 344         {
 345         case ENOBUFS:
 346           continue;
 347         case EAGAIN:
 348           {
 349             memcached_return rc;
 350             rc= io_wait(ptr, MEM_WRITE);
 351
 352             if (rc == MEMCACHED_SUCCESS)
 353               continue;
 354
 355             memcached_quit_server(ptr, 1);
 356             return -1;
 357           }
 358         default:
 359           memcached_quit_server(ptr, 1);
 360           ptr->cached_errno= errno;
 361           *error= MEMCACHED_ERRNO;
 362           return -1;
 363         }
 364       }
 365     }
 366
 367     ptr->io_bytes_sent += sent_length;
 368
 369     local_write_ptr+= sent_length;
 370     write_length-= sent_length;
 371     return_length+= sent_length;
 372   }
 373
 374   WATCHPOINT_ASSERT(write_length == 0);
 375   // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
 376   // ptr->write_buffer_offset);
 377   ptr->write_buffer_offset= 0;
 378
 379   return return_length;
 380 }
 381
 382 /*
 383   Eventually we will just kill off the server with the problem.
 384 */
 385 void memcached_io_reset(memcached_server_st *ptr)
 386 {
 387   memcached_quit_server(ptr, 0);
 388 }