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