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   {
  43     memcached_return rc=memcached_purge(ptr);
  44     if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
  45        return MEMCACHED_FAILURE;
  46   }
  47
  48   error= poll(fds, 1, ptr->root->poll_timeout);
  49
  50   if (error == 1)
  51     return MEMCACHED_SUCCESS;
  52   else if (error == 0)
  53   {
  54     return MEMCACHED_TIMEOUT;
  55   }
  56
  57   /* Imposssible for anything other then -1 */
  58   WATCHPOINT_ASSERT(error == -1);
  59   memcached_quit_server(ptr, 1);
  60
  61   return MEMCACHED_FAILURE;
  62
  63 }
  64
  65 #ifdef UNUSED
  66 void memcached_io_preread(memcached_st *ptr)
  67 {
  68   unsigned int x;
  69
  70   return;
  71
  72   for (x= 0; x < ptr->number_of_hosts; x++)
  73   {
  74     if (memcached_server_response_count(ptr, x) &&
  75         ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
  76     {
  77       size_t data_read;
  78
  79       data_read= read(ptr->hosts[x].fd,
  80                       ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
  81                       MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length);
  82       if (data_read == -1)
  83         continue;
  84
  85       ptr->hosts[x].read_buffer_length+= data_read;
  86       ptr->hosts[x].read_data_length+= data_read;
  87     }
  88   }
  89 }
  90 #endif
  91
  92 ssize_t memcached_io_read(memcached_server_st *ptr,
  93                           void *buffer, size_t length)
  94 {
  95   char *buffer_ptr;
  96
  97   buffer_ptr= buffer;
  98
  99   while (length)
 100   {
 101     if (!ptr->read_buffer_length)
 102     {
 103       ssize_t data_read;
 104
 105       while (1)
 106       {
 107         data_read= read(ptr->fd,
 108                         ptr->read_buffer,
 109                         MEMCACHED_MAX_BUFFER);
 110         if (data_read > 0)
 111           break;
 112         else if (data_read == -1)
 113         {
 114           ptr->cached_errno= errno;
 115           switch (errno)
 116           {
 117           case EAGAIN:
 118           case EINTR:
 119             {
 120               memcached_return rc;
 121
 122               rc= io_wait(ptr, MEM_READ);
 123
 124               if (rc == MEMCACHED_SUCCESS)
 125                 continue;
 126             }
 127           /* fall trough */
 128           default:
 129             {
 130               memcached_quit_server(ptr, 1);
 131               return -1;
 132             }
 133           }
 134         }
 135         else
 136         {
 137           /*
 138             EOF. Any data received so far is incomplete
 139             so discard it. This always reads by byte in case of TCP
 140             and protocol enforcement happens at memcached_response()
 141             looking for '\n'. We do not care for UDB which requests 8 bytes
 142             at once. Generally, this means that connection went away. Since
 143             for blocking I/O we do not return 0 and for non-blocking case
 144             it will return EGAIN if data is not immediatly available.
 145           */
 146           memcached_quit_server(ptr, 1);
 147           return -1;
 148         }
 149       }
 150
 151       ptr->io_bytes_sent = 0;
 152       ptr->read_data_length= data_read;
 153       ptr->read_buffer_length= data_read;
 154       ptr->read_ptr= ptr->read_buffer;
 155     }
 156
 157     if (length > 1)
 158     {
 159       size_t difference;
 160
 161       difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
 162
 163       memcpy(buffer_ptr, ptr->read_ptr, difference);
 164       length -= difference;
 165       ptr->read_ptr+= difference;
 166       ptr->read_buffer_length-= difference;
 167       buffer_ptr+= difference;
 168     }
 169     else
 170     {
 171       *buffer_ptr= *ptr->read_ptr;
 172       ptr->read_ptr++;
 173       ptr->read_buffer_length--;
 174       buffer_ptr++;
 175       break;
 176     }
 177   }
 178
 179   return (size_t)(buffer_ptr - (char*)buffer);
 180 }
 181
 182 ssize_t memcached_io_write(memcached_server_st *ptr,
 183                            const void *buffer, size_t length, char with_flush)
 184 {
 185   size_t original_length;
 186   const char* buffer_ptr;
 187
 188   WATCHPOINT_ASSERT(ptr->fd != -1);
 189
 190   original_length= length;
 191   buffer_ptr= buffer;
 192
 193   while (length)
 194   {
 195     char *write_ptr;
 196     size_t should_write;
 197
 198     should_write= MEMCACHED_MAX_BUFFER - ptr->write_buffer_offset;
 199     write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
 200
 201     should_write= (should_write < length) ? should_write : length;
 202
 203     memcpy(write_ptr, buffer_ptr, should_write);
 204     ptr->write_buffer_offset+= should_write;
 205     buffer_ptr+= should_write;
 206     length-= should_write;
 207
 208     if (ptr->write_buffer_offset == MEMCACHED_MAX_BUFFER)
 209     {
 210       memcached_return rc;
 211       ssize_t sent_length;
 212
 213       WATCHPOINT_ASSERT(ptr->fd != -1);
 214       sent_length= io_flush(ptr, &rc);
 215       if (sent_length == -1)
 216         return -1;
 217
 218       /* If io_flush calls memcached_purge, sent_length may be 0 */
 219       if (sent_length != 0)
 220         WATCHPOINT_ASSERT(sent_length == MEMCACHED_MAX_BUFFER);
 221     }
 222   }
 223
 224   if (with_flush)
 225   {
 226     memcached_return rc;
 227     WATCHPOINT_ASSERT(ptr->fd != -1);
 228     if (io_flush(ptr, &rc) == -1)
 229       return -1;
 230   }
 231
 232   return original_length;
 233 }
 234
 235 memcached_return memcached_io_close(memcached_server_st *ptr)
 236 {
 237   int r;
 238
 239   if (ptr->fd == -1)
 240     return MEMCACHED_SUCCESS;
 241
 242   /* in case of death shutdown to avoid blocking at close() */
 243   if (1)
 244   {
 245     r= shutdown(ptr->fd, SHUT_RDWR);
 246
 247 #ifdef HAVE_DEBUG
 248     if (r && errno != ENOTCONN)
 249     {
 250       WATCHPOINT_NUMBER(ptr->fd);
 251       WATCHPOINT_ERRNO(errno);
 252       WATCHPOINT_ASSERT(errno);
 253     }
 254 #endif
 255   }
 256
 257   r= close(ptr->fd);
 258 #ifdef HAVE_DEBUG
 259   if (r != 0)
 260     WATCHPOINT_ERRNO(errno);
 261 #endif
 262
 263   return MEMCACHED_SUCCESS;
 264 }
 265
 266 static ssize_t io_flush(memcached_server_st *ptr,
 267                         memcached_return *error)
 268 {
 269   /*
 270   ** We might want to purge the input buffer if we haven't consumed
 271   ** any output yet... The test for the limits is the purge is inline
 272   ** in the purge function to avoid duplicating the logic..
 273   */
 274   {
 275      memcached_return rc;
 276      WATCHPOINT_ASSERT(ptr->fd != -1);
 277      rc= memcached_purge(ptr);
 278
 279      if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
 280        return -1;
 281   }
 282   ssize_t sent_length;
 283   size_t return_length;
 284   char *local_write_ptr= ptr->write_buffer;
 285   size_t write_length= ptr->write_buffer_offset;
 286
 287   *error= MEMCACHED_SUCCESS;
 288
 289   WATCHPOINT_ASSERT(ptr->fd != -1);
 290
 291   if (ptr->write_buffer_offset == 0)
 292     return 0;
 293
 294   /* Looking for memory overflows */
 295 #if defined(HAVE_DEBUG)
 296   if (write_length == MEMCACHED_MAX_BUFFER)
 297     WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
 298   WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
 299 #endif
 300
 301   return_length= 0;
 302   while (write_length)
 303   {
 304     WATCHPOINT_ASSERT(ptr->fd != -1);
 305     WATCHPOINT_ASSERT(write_length > 0);
 306     sent_length= 0;
 307     if (ptr->type == MEMCACHED_CONNECTION_UDP)
 308     {
 309       struct addrinfo *ai;
 310
 311       ai= ptr->address_info;
 312
 313       /* Crappy test code */
 314       char buffer[HUGE_STRING_LEN + 8];
 315       memset(buffer, 0, HUGE_STRING_LEN + 8);
 316       memcpy (buffer+8, local_write_ptr, write_length);
 317       buffer[0]= 0;
 318       buffer[1]= 0;
 319       buffer[2]= 0;
 320       buffer[3]= 0;
 321       buffer[4]= 0;
 322       buffer[5]= 1;
 323       buffer[6]= 0;
 324       buffer[7]= 0;
 325       sent_length= sendto(ptr->fd, buffer, write_length + 8, 0,
 326                           (struct sockaddr *)ai->ai_addr,
 327                           ai->ai_addrlen);
 328       if (sent_length == -1)
 329       {
 330         WATCHPOINT_ERRNO(errno);
 331         WATCHPOINT_ASSERT(0);
 332       }
 333       sent_length-= 8; /* We remove the header */
 334     }
 335     else
 336     {
 337       WATCHPOINT_ASSERT(ptr->fd != -1);
 338       if ((sent_length= write(ptr->fd, local_write_ptr,
 339                               write_length)) == -1)
 340       {
 341         switch (errno)
 342         {
 343         case ENOBUFS:
 344           continue;
 345         case EAGAIN:
 346           {
 347             memcached_return rc;
 348             rc= io_wait(ptr, MEM_WRITE);
 349
 350             if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_TIMEOUT)
 351               continue;
 352
 353             memcached_quit_server(ptr, 1);
 354             return -1;
 355           }
 356         default:
 357           memcached_quit_server(ptr, 1);
 358           ptr->cached_errno= errno;
 359           *error= MEMCACHED_ERRNO;
 360           return -1;
 361         }
 362       }
 363     }
 364
 365     ptr->io_bytes_sent += sent_length;
 366
 367     local_write_ptr+= sent_length;
 368     write_length-= sent_length;
 369     return_length+= sent_length;
 370   }
 371
 372   WATCHPOINT_ASSERT(write_length == 0);
 373   // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
 374   // ptr->write_buffer_offset);
 375   ptr->write_buffer_offset= 0;
 376
 377   return return_length;
 378 }
 379
 380 /*
 381   Eventually we will just kill off the server with the problem.
 382 */
 383 void memcached_io_reset(memcached_server_st *ptr)
 384 {
 385   memcached_quit_server(ptr, 1);
 386 }
 387
 388 /**
 389  * Read a given number of bytes from the server and place it into a specific
 390  * buffer. Reset the IO channel on this server if an error occurs.
 391  */
 392 memcached_return memcached_safe_read(memcached_server_st *ptr,
 393                                      void *dta,
 394                                      size_t size)
 395 {
 396   size_t offset= 0;
 397   char *data= dta;
 398
 399   while (offset < size)
 400   {
 401     ssize_t nread= memcached_io_read(ptr, data + offset, size - offset);
 402     if (nread <= 0)
 403     {
 404       memcached_io_reset(ptr);
 405       return MEMCACHED_UNKNOWN_READ_FAILURE;
 406     }
 407     offset+= nread;
 408   }
 409
 410   return MEMCACHED_SUCCESS;
 411 }