Merge in removal of setting infinite no_block
[m6w6/libmemcached] / libmemcached / io.c
1 /* LibMemcached
2 * Copyright (C) 2006-2009 Brian Aker
3 * All rights reserved.
4 *
5 * Use and distribution licensed under the BSD license. See
6 * the COPYING file in the parent directory for full text.
7 *
8 * Summary: Server IO, Not public!
9 *
10 */
11
12
13 #include "common.h"
14
15 typedef enum {
16 MEM_READ,
17 MEM_WRITE
18 } memc_read_or_write;
19
20 static ssize_t io_flush(memcached_server_write_instance_st ptr,
21 memcached_return_t *error);
22 static void increment_udp_message_id(memcached_server_write_instance_st ptr);
23
24 static memcached_return_t io_wait(memcached_server_write_instance_st ptr,
25 memc_read_or_write read_or_write)
26 {
27 struct pollfd fds= {
28 .fd= ptr->fd,
29 .events = POLLIN
30 };
31 int error;
32
33 if (read_or_write == MEM_WRITE) /* write */
34 {
35 fds.events= POLLOUT;
36 WATCHPOINT_SET(ptr->io_wait_count.write++);
37 }
38 else
39 {
40 WATCHPOINT_SET(ptr->io_wait_count.read++);
41 }
42
43 /*
44 ** We are going to block on write, but at least on Solaris we might block
45 ** on write if we haven't read anything from our input buffer..
46 ** Try to purge the input buffer if we don't do any flow control in the
47 ** application layer (just sending a lot of data etc)
48 ** The test is moved down in the purge function to avoid duplication of
49 ** the test.
50 */
51 if (read_or_write == MEM_WRITE)
52 {
53 memcached_return_t rc= memcached_purge(ptr);
54 if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
55 return MEMCACHED_FAILURE;
56 }
57
58 size_t loop_max= 5;
59 while (--loop_max) // While loop is for ERESTART or EINTR
60 {
61 error= poll(&fds, 1, ptr->root->poll_timeout);
62
63 switch (error)
64 {
65 case 1: // Success!
66 WATCHPOINT_IF_LABELED_NUMBER(read_or_write && loop_max < 4, "read() times we had to loop, decremented down from 5", loop_max);
67 WATCHPOINT_IF_LABELED_NUMBER(!read_or_write && loop_max < 4, "write() times we had to loop, decremented down from 5", loop_max);
68
69 return MEMCACHED_SUCCESS;
70 case 0: // Timeout occured, we let the while() loop do its thing.
71 return MEMCACHED_TIMEOUT;
72 default:
73 WATCHPOINT_ERRNO(get_socket_errno());
74 switch (get_socket_errno())
75 {
76 #ifdef TARGET_OS_LINUX
77 case ERESTART:
78 #endif
79 case EINTR:
80 break;
81 default:
82 if (fds.revents & POLLERR)
83 {
84 int err;
85 socklen_t len= sizeof (err);
86 (void)getsockopt(ptr->fd, SOL_SOCKET, SO_ERROR, &err, &len);
87 ptr->cached_errno= (err == 0) ? get_socket_errno() : err;
88 }
89 else
90 {
91 ptr->cached_errno= get_socket_errno();
92 }
93 memcached_quit_server(ptr, true);
94
95 return MEMCACHED_FAILURE;
96 }
97 }
98 }
99
100 /* Imposssible for anything other then -1 */
101 WATCHPOINT_ASSERT(error == -1);
102 ptr->cached_errno= get_socket_errno();
103 memcached_quit_server(ptr, true);
104
105 return MEMCACHED_FAILURE;
106 }
107
108 /**
109 * Try to fill the input buffer for a server with as much
110 * data as possible.
111 *
112 * @param ptr the server to pack
113 */
114 static bool repack_input_buffer(memcached_server_write_instance_st ptr)
115 {
116 if (ptr->read_ptr != ptr->read_buffer)
117 {
118 /* Move all of the data to the beginning of the buffer so
119 ** that we can fit more data into the buffer...
120 */
121 memmove(ptr->read_buffer, ptr->read_ptr, ptr->read_buffer_length);
122 ptr->read_ptr= ptr->read_buffer;
123 ptr->read_data_length= ptr->read_buffer_length;
124 }
125
126 /* There is room in the buffer, try to fill it! */
127 if (ptr->read_buffer_length != MEMCACHED_MAX_BUFFER)
128 {
129 /* Just try a single read to grab what's available */
130 ssize_t nr= recv(ptr->fd,
131 ptr->read_ptr + ptr->read_data_length,
132 MEMCACHED_MAX_BUFFER - ptr->read_data_length,
133 0);
134
135 if (nr > 0)
136 {
137 ptr->read_data_length+= (size_t)nr;
138 ptr->read_buffer_length+= (size_t)nr;
139 return true;
140 }
141 }
142 return false;
143 }
144
145 /**
146 * If the we have callbacks connected to this server structure
147 * we may start process the input queue and fire the callbacks
148 * for the incomming messages. This function is _only_ called
149 * when the input buffer is full, so that we _know_ that we have
150 * at least _one_ message to process.
151 *
152 * @param ptr the server to star processing iput messages for
153 * @return true if we processed anything, false otherwise
154 */
155 static bool process_input_buffer(memcached_server_write_instance_st ptr)
156 {
157 /*
158 ** We might be able to process some of the response messages if we
159 ** have a callback set up
160 */
161 if (ptr->root->callbacks != NULL && ptr->root->flags.use_udp == false)
162 {
163 /*
164 * We might have responses... try to read them out and fire
165 * callbacks
166 */
167 memcached_callback_st cb= *ptr->root->callbacks;
168
169 memcached_set_processing_input((memcached_st *)ptr->root, true);
170
171 char buffer[MEMCACHED_DEFAULT_COMMAND_SIZE];
172 memcached_return_t error;
173 memcached_st *root= (memcached_st *)ptr->root;
174 error= memcached_response(ptr, buffer, sizeof(buffer),
175 &root->result);
176
177 memcached_set_processing_input(root, false);
178
179 if (error == MEMCACHED_SUCCESS)
180 {
181 for (unsigned int x= 0; x < cb.number_of_callback; x++)
182 {
183 error= (*cb.callback[x])(ptr->root, &root->result, cb.context);
184 if (error != MEMCACHED_SUCCESS)
185 break;
186 }
187
188 /* @todo what should I do with the error message??? */
189 }
190 /* @todo what should I do with other error messages?? */
191 return true;
192 }
193
194 return false;
195 }
196
197 static inline void memcached_io_cork_push(memcached_server_st *ptr)
198 {
199 (void)ptr;
200 #ifdef CORK
201 if (ptr->root->flags.cork == false || ptr->state.is_corked)
202 return;
203
204 int enable= 1;
205 int err= setsockopt(ptr->fd, IPPROTO_TCP, CORK,
206 &enable, (socklen_t)sizeof(int));
207 if (! err)
208 ptr->state.is_corked= true;
209
210 WATCHPOINT_ASSERT(ptr->state.is_corked == true);
211 #endif
212 }
213
214 static inline void memcached_io_cork_pop(memcached_server_st *ptr)
215 {
216 (void)ptr;
217 #ifdef CORK
218 if (ptr->root->flags.cork == false || ptr->state.is_corked == false)
219 return;
220
221 int enable= 0;
222 int err= setsockopt(ptr->fd, IPPROTO_TCP, CORK,
223 &enable, (socklen_t)sizeof(int));
224 if (! err)
225 ptr->state.is_corked= false;
226
227 WATCHPOINT_ASSERT(ptr->state.is_corked == false);
228 #endif
229 }
230
231 #if 0 // Dead code, this should be removed.
232 void memcached_io_preread(memcached_st *ptr)
233 {
234 unsigned int x;
235
236 return;
237
238 for (x= 0; x < memcached_server_count(ptr); x++)
239 {
240 if (memcached_server_response_count(ptr, x) &&
241 ptr->hosts[x].read_data_length < MEMCACHED_MAX_BUFFER )
242 {
243 size_t data_read;
244
245 data_read= recv(ptr->hosts[x].fd,
246 ptr->hosts[x].read_ptr + ptr->hosts[x].read_data_length,
247 MEMCACHED_MAX_BUFFER - ptr->hosts[x].read_data_length, 0);
248 if (data_read == SOCKET_ERROR)
249 continue;
250
251 ptr->hosts[x].read_buffer_length+= data_read;
252 ptr->hosts[x].read_data_length+= data_read;
253 }
254 }
255 }
256 #endif
257
258 memcached_return_t memcached_io_read(memcached_server_write_instance_st ptr,
259 void *buffer, size_t length, ssize_t *nread)
260 {
261 char *buffer_ptr;
262
263 buffer_ptr= buffer;
264
265 while (length)
266 {
267 if (!ptr->read_buffer_length)
268 {
269 ssize_t data_read;
270
271 while (1)
272 {
273 data_read= recv(ptr->fd, ptr->read_buffer, MEMCACHED_MAX_BUFFER, 0);
274 if (data_read > 0)
275 {
276 break;
277 }
278 else if (data_read == SOCKET_ERROR)
279 {
280 ptr->cached_errno= get_socket_errno();
281 memcached_return_t rc= MEMCACHED_ERRNO;
282 switch (get_socket_errno())
283 {
284 case EWOULDBLOCK:
285 #ifdef USE_EAGAIN
286 case EAGAIN:
287 #endif
288 case EINTR:
289 #ifdef TARGET_OS_LINUX
290 case ERESTART:
291 #endif
292 if ((rc= io_wait(ptr, MEM_READ)) == MEMCACHED_SUCCESS)
293 continue;
294 /* fall through */
295
296 default:
297 {
298 memcached_quit_server(ptr, true);
299 *nread= -1;
300 return rc;
301 }
302 }
303 }
304 else
305 {
306 /*
307 EOF. Any data received so far is incomplete
308 so discard it. This always reads by byte in case of TCP
309 and protocol enforcement happens at memcached_response()
310 looking for '\n'. We do not care for UDB which requests 8 bytes
311 at once. Generally, this means that connection went away. Since
312 for blocking I/O we do not return 0 and for non-blocking case
313 it will return EGAIN if data is not immediatly available.
314 */
315 WATCHPOINT_STRING("We had a zero length recv()");
316 memcached_quit_server(ptr, true);
317 *nread= -1;
318 return MEMCACHED_UNKNOWN_READ_FAILURE;
319 }
320 }
321
322 ptr->io_bytes_sent = 0;
323 ptr->read_data_length= (size_t) data_read;
324 ptr->read_buffer_length= (size_t) data_read;
325 ptr->read_ptr= ptr->read_buffer;
326 }
327
328 if (length > 1)
329 {
330 size_t difference;
331
332 difference= (length > ptr->read_buffer_length) ? ptr->read_buffer_length : length;
333
334 memcpy(buffer_ptr, ptr->read_ptr, difference);
335 length -= difference;
336 ptr->read_ptr+= difference;
337 ptr->read_buffer_length-= difference;
338 buffer_ptr+= difference;
339 }
340 else
341 {
342 *buffer_ptr= *ptr->read_ptr;
343 ptr->read_ptr++;
344 ptr->read_buffer_length--;
345 buffer_ptr++;
346 break;
347 }
348 }
349
350 ptr->server_failure_counter= 0;
351 *nread = (ssize_t)(buffer_ptr - (char*)buffer);
352 return MEMCACHED_SUCCESS;
353 }
354
355 static ssize_t _io_write(memcached_server_write_instance_st ptr,
356 const void *buffer, size_t length, bool with_flush)
357 {
358 size_t original_length;
359 const char* buffer_ptr;
360
361 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
362
363 original_length= length;
364 buffer_ptr= buffer;
365
366 /* more writable data is coming if a flush isn't required, so delay send */
367 if (! with_flush)
368 {
369 memcached_io_cork_push(ptr);
370 }
371
372 while (length)
373 {
374 char *write_ptr;
375 size_t should_write;
376 size_t buffer_end;
377
378 if (ptr->type == MEMCACHED_CONNECTION_UDP)
379 {
380 //UDP does not support partial writes
381 buffer_end= MAX_UDP_DATAGRAM_LENGTH;
382 should_write= length;
383 if (ptr->write_buffer_offset + should_write > buffer_end)
384 {
385 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
386 return -1;
387 }
388 }
389 else
390 {
391 buffer_end= MEMCACHED_MAX_BUFFER;
392 should_write= buffer_end - ptr->write_buffer_offset;
393 should_write= (should_write < length) ? should_write : length;
394 }
395
396 write_ptr= ptr->write_buffer + ptr->write_buffer_offset;
397 memcpy(write_ptr, buffer_ptr, should_write);
398 ptr->write_buffer_offset+= should_write;
399 buffer_ptr+= should_write;
400 length-= should_write;
401
402 if (ptr->write_buffer_offset == buffer_end && ptr->type != MEMCACHED_CONNECTION_UDP)
403 {
404 memcached_return_t rc;
405 ssize_t sent_length;
406
407 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
408 sent_length= io_flush(ptr, &rc);
409 if (sent_length == -1)
410 {
411 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
412 return -1;
413 }
414
415 /* If io_flush calls memcached_purge, sent_length may be 0 */
416 unlikely (sent_length != 0)
417 {
418 WATCHPOINT_ASSERT(sent_length == (ssize_t)buffer_end);
419 }
420 }
421 }
422
423 if (with_flush)
424 {
425 memcached_return_t rc;
426 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
427 if (io_flush(ptr, &rc) == -1)
428 {
429 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
430 return -1;
431 }
432
433 memcached_io_cork_pop(ptr);
434 }
435
436 return (ssize_t) original_length;
437 }
438
439 ssize_t memcached_io_write(memcached_server_write_instance_st ptr,
440 const void *buffer, size_t length, bool with_flush)
441 {
442 return _io_write(ptr, buffer, length, with_flush);
443 }
444
445 ssize_t memcached_io_writev(memcached_server_write_instance_st ptr,
446 const struct libmemcached_io_vector_st *vector,
447 size_t number_of, bool with_flush)
448 {
449 ssize_t total= 0;
450
451 for (size_t x= 0; x < number_of; x++, vector++)
452 {
453 ssize_t returnable;
454
455 if ((returnable= _io_write(ptr, vector->buffer, vector->length, false)) == -1)
456 {
457 return -1;
458 }
459 total+= returnable;
460 }
461
462 if (with_flush)
463 {
464 if (memcached_io_write(ptr, NULL, 0, true) == -1)
465 {
466 return -1;
467 }
468 }
469
470 return total;
471 }
472
473
474 memcached_return_t memcached_io_close(memcached_server_write_instance_st ptr)
475 {
476 if (ptr->fd == INVALID_SOCKET)
477 {
478 return MEMCACHED_SUCCESS;
479 }
480
481 /* in case of death shutdown to avoid blocking at close() */
482 if (shutdown(ptr->fd, SHUT_RDWR) == SOCKET_ERROR && get_socket_errno() != ENOTCONN)
483 {
484 WATCHPOINT_NUMBER(ptr->fd);
485 WATCHPOINT_ERRNO(get_socket_errno());
486 WATCHPOINT_ASSERT(get_socket_errno());
487 }
488
489 if (closesocket(ptr->fd) == SOCKET_ERROR)
490 {
491 WATCHPOINT_ERRNO(get_socket_errno());
492 }
493
494 return MEMCACHED_SUCCESS;
495 }
496
497 memcached_server_write_instance_st memcached_io_get_readable_server(memcached_st *memc)
498 {
499 #define MAX_SERVERS_TO_POLL 100
500 struct pollfd fds[MAX_SERVERS_TO_POLL];
501 unsigned int host_index= 0;
502
503 for (uint32_t x= 0;
504 x< memcached_server_count(memc) && host_index < MAX_SERVERS_TO_POLL;
505 ++x)
506 {
507 memcached_server_write_instance_st instance=
508 memcached_server_instance_fetch(memc, x);
509
510 if (instance->read_buffer_length > 0) /* I have data in the buffer */
511 return instance;
512
513 if (memcached_server_response_count(instance) > 0)
514 {
515 fds[host_index].events = POLLIN;
516 fds[host_index].revents = 0;
517 fds[host_index].fd = instance->fd;
518 ++host_index;
519 }
520 }
521
522 if (host_index < 2)
523 {
524 /* We have 0 or 1 server with pending events.. */
525 for (uint32_t x= 0; x< memcached_server_count(memc); ++x)
526 {
527 memcached_server_write_instance_st instance=
528 memcached_server_instance_fetch(memc, x);
529
530 if (memcached_server_response_count(instance) > 0)
531 {
532 return instance;
533 }
534 }
535
536 return NULL;
537 }
538
539 int err= poll(fds, host_index, memc->poll_timeout);
540 switch (err) {
541 case -1:
542 memc->cached_errno = get_socket_errno();
543 /* FALLTHROUGH */
544 case 0:
545 break;
546 default:
547 for (size_t x= 0; x < host_index; ++x)
548 {
549 if (fds[x].revents & POLLIN)
550 {
551 for (uint32_t y= 0; y < memcached_server_count(memc); ++y)
552 {
553 memcached_server_write_instance_st instance=
554 memcached_server_instance_fetch(memc, y);
555
556 if (instance->fd == fds[x].fd)
557 return instance;
558 }
559 }
560 }
561 }
562
563 return NULL;
564 }
565
566 static ssize_t io_flush(memcached_server_write_instance_st ptr,
567 memcached_return_t *error)
568 {
569 /*
570 ** We might want to purge the input buffer if we haven't consumed
571 ** any output yet... The test for the limits is the purge is inline
572 ** in the purge function to avoid duplicating the logic..
573 */
574 {
575 memcached_return_t rc;
576 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
577 rc= memcached_purge(ptr);
578
579 if (rc != MEMCACHED_SUCCESS && rc != MEMCACHED_STORED)
580 {
581 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
582 return -1;
583 }
584 }
585 ssize_t sent_length;
586 size_t return_length;
587 char *local_write_ptr= ptr->write_buffer;
588 size_t write_length= ptr->write_buffer_offset;
589
590 *error= MEMCACHED_SUCCESS;
591
592 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
593
594 // UDP Sanity check, make sure that we are not sending somthing too big
595 if (ptr->type == MEMCACHED_CONNECTION_UDP && write_length > MAX_UDP_DATAGRAM_LENGTH)
596 {
597 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
598 return -1;
599 }
600
601 if (ptr->write_buffer_offset == 0 || (ptr->type == MEMCACHED_CONNECTION_UDP
602 && ptr->write_buffer_offset == UDP_DATAGRAM_HEADER_LENGTH))
603 return 0;
604
605 /* Looking for memory overflows */
606 #if defined(DEBUG)
607 if (write_length == MEMCACHED_MAX_BUFFER)
608 WATCHPOINT_ASSERT(ptr->write_buffer == local_write_ptr);
609 WATCHPOINT_ASSERT((ptr->write_buffer + MEMCACHED_MAX_BUFFER) >= (local_write_ptr + write_length));
610 #endif
611
612 return_length= 0;
613 while (write_length)
614 {
615 WATCHPOINT_ASSERT(ptr->fd != INVALID_SOCKET);
616 WATCHPOINT_ASSERT(write_length > 0);
617 sent_length= 0;
618 if (ptr->type == MEMCACHED_CONNECTION_UDP)
619 increment_udp_message_id(ptr);
620
621 sent_length= send(ptr->fd, local_write_ptr, write_length, 0);
622 if (sent_length == SOCKET_ERROR)
623 {
624 ptr->cached_errno= get_socket_errno();
625 #if 0 // @todo I should look at why we hit this bit of code hard frequently
626 WATCHPOINT_ERRNO(get_socket_errno());
627 WATCHPOINT_NUMBER(get_socket_errno());
628 #endif
629 switch (get_socket_errno())
630 {
631 case ENOBUFS:
632 continue;
633 case EWOULDBLOCK:
634 #ifdef USE_EAGAIN
635 case EAGAIN:
636 #endif
637 {
638 /*
639 * We may be blocked on write because the input buffer
640 * is full. Let's check if we have room in our input
641 * buffer for more data and retry the write before
642 * waiting..
643 */
644 if (repack_input_buffer(ptr) ||
645 process_input_buffer(ptr))
646 continue;
647
648 memcached_return_t rc;
649 rc= io_wait(ptr, MEM_WRITE);
650
651 if (rc == MEMCACHED_SUCCESS || rc == MEMCACHED_TIMEOUT)
652 continue;
653
654 memcached_quit_server(ptr, true);
655 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
656 return -1;
657 }
658 default:
659 memcached_quit_server(ptr, true);
660 *error= MEMCACHED_ERRNO;
661 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
662 return -1;
663 }
664 }
665
666 if (ptr->type == MEMCACHED_CONNECTION_UDP &&
667 (size_t)sent_length != write_length)
668 {
669 memcached_quit_server(ptr, true);
670 fprintf(stderr, "%s:%d (%s)\n", __FILE__, __LINE__,__func__);fflush(stdout);
671 return -1;
672 }
673
674 ptr->io_bytes_sent += (uint32_t) sent_length;
675
676 local_write_ptr+= sent_length;
677 write_length-= (uint32_t) sent_length;
678 return_length+= (uint32_t) sent_length;
679 }
680
681 WATCHPOINT_ASSERT(write_length == 0);
682 // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
683 // ptr->write_buffer_offset);
684
685 // if we are a udp server, the begining of the buffer is reserverd for
686 // the upd frame header
687 if (ptr->type == MEMCACHED_CONNECTION_UDP)
688 ptr->write_buffer_offset= UDP_DATAGRAM_HEADER_LENGTH;
689 else
690 ptr->write_buffer_offset= 0;
691
692 return (ssize_t) return_length;
693 }
694
695 /*
696 Eventually we will just kill off the server with the problem.
697 */
698 void memcached_io_reset(memcached_server_write_instance_st ptr)
699 {
700 memcached_quit_server(ptr, true);
701 }
702
703 /**
704 * Read a given number of bytes from the server and place it into a specific
705 * buffer. Reset the IO channel on this server if an error occurs.
706 */
707 memcached_return_t memcached_safe_read(memcached_server_write_instance_st ptr,
708 void *dta,
709 size_t size)
710 {
711 size_t offset= 0;
712 char *data= dta;
713
714 while (offset < size)
715 {
716 ssize_t nread;
717 memcached_return_t rc= memcached_io_read(ptr, data + offset, size - offset,
718 &nread);
719 if (rc != MEMCACHED_SUCCESS)
720 return rc;
721
722 offset+= (size_t) nread;
723 }
724
725 return MEMCACHED_SUCCESS;
726 }
727
728 memcached_return_t memcached_io_readline(memcached_server_write_instance_st ptr,
729 char *buffer_ptr,
730 size_t size)
731 {
732 bool line_complete= false;
733 size_t total_nr= 0;
734
735 while (!line_complete)
736 {
737 if (ptr->read_buffer_length == 0)
738 {
739 /*
740 * We don't have any data in the buffer, so let's fill the read
741 * buffer. Call the standard read function to avoid duplicating
742 * the logic.
743 */
744 ssize_t nread;
745 memcached_return_t rc= memcached_io_read(ptr, buffer_ptr, 1, &nread);
746 if (rc != MEMCACHED_SUCCESS)
747 return rc;
748
749 if (*buffer_ptr == '\n')
750 line_complete= true;
751
752 ++buffer_ptr;
753 ++total_nr;
754 }
755
756 /* Now let's look in the buffer and copy as we go! */
757 while (ptr->read_buffer_length && total_nr < size && !line_complete)
758 {
759 *buffer_ptr = *ptr->read_ptr;
760 if (*buffer_ptr == '\n')
761 line_complete = true;
762 --ptr->read_buffer_length;
763 ++ptr->read_ptr;
764 ++total_nr;
765 ++buffer_ptr;
766 }
767
768 if (total_nr == size)
769 return MEMCACHED_PROTOCOL_ERROR;
770 }
771
772 return MEMCACHED_SUCCESS;
773 }
774
775 /*
776 * The udp request id consists of two seperate sections
777 * 1) The thread id
778 * 2) The message number
779 * The thread id should only be set when the memcached_st struct is created
780 * and should not be changed.
781 *
782 * The message num is incremented for each new message we send, this function
783 * extracts the message number from message_id, increments it and then
784 * writes the new value back into the header
785 */
786 static void increment_udp_message_id(memcached_server_write_instance_st ptr)
787 {
788 struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
789 uint16_t cur_req= get_udp_datagram_request_id(header);
790 int msg_num= get_msg_num_from_request_id(cur_req);
791 int thread_id= get_thread_id_from_request_id(cur_req);
792
793 if (((++msg_num) & UDP_REQUEST_ID_THREAD_MASK) != 0)
794 msg_num= 0;
795
796 header->request_id= htons((uint16_t) (thread_id | msg_num));
797 }
798
799 memcached_return_t memcached_io_init_udp_header(memcached_server_write_instance_st ptr, uint16_t thread_id)
800 {
801 if (thread_id > UDP_REQUEST_ID_MAX_THREAD_ID)
802 return MEMCACHED_FAILURE;
803
804 struct udp_datagram_header_st *header= (struct udp_datagram_header_st *)ptr->write_buffer;
805 header->request_id= htons((uint16_t) (generate_udp_request_thread_id(thread_id)));
806 header->num_datagrams= htons(1);
807 header->sequence_number= htons(0);
808
809 return MEMCACHED_SUCCESS;
810 }