2 * Copyright (C) 2006-2009 Brian Aker
5 * Use and distribution licensed under the BSD license. See
6 * the COPYING file in the parent directory for full text.
8 * Summary: Server IO, Not public!
14 #include "memcached_io.h"
15 #include <sys/select.h>
23 static ssize_t
io_flush(memcached_server_st
*ptr
, memcached_return_t
*error
);
24 static void increment_udp_message_id(memcached_server_st
*ptr
);
26 static memcached_return_t
io_wait(memcached_server_st
*ptr
,
27 memc_read_or_write read_or_write
)
35 unlikely (read_or_write
== MEM_WRITE
) /* write */
39 ** We are going to block on write, but at least on Solaris we might block
40 ** on write if we haven't read anything from our input buffer..
41 ** Try to purge the input buffer if we don't do any flow control in the
42 ** application layer (just sending a lot of data etc)
43 ** The test is moved down in the purge function to avoid duplication of
46 if (read_or_write
== MEM_WRITE
)
48 memcached_return_t rc
= memcached_purge(ptr
);
49 if (rc
!= MEMCACHED_SUCCESS
&& rc
!= MEMCACHED_STORED
)
50 return MEMCACHED_FAILURE
;
53 int timeout
= ptr
->root
->poll_timeout
;
54 if (ptr
->root
->flags
.no_block
== false)
57 error
= poll(&fds
, 1, timeout
);
60 return MEMCACHED_SUCCESS
;
62 return MEMCACHED_TIMEOUT
;
64 /* Imposssible for anything other then -1 */
65 WATCHPOINT_ASSERT(error
== -1);
66 memcached_quit_server(ptr
, 1);
68 return MEMCACHED_FAILURE
;
72 * Try to fill the input buffer for a server with as much
75 * @param ptr the server to pack
77 static bool repack_input_buffer(memcached_server_st
*ptr
)
79 if (ptr
->read_ptr
!= ptr
->read_buffer
)
81 /* Move all of the data to the beginning of the buffer so
82 ** that we can fit more data into the buffer...
84 memmove(ptr
->read_buffer
, ptr
->read_ptr
, ptr
->read_buffer_length
);
85 ptr
->read_ptr
= ptr
->read_buffer
;
86 ptr
->read_data_length
= ptr
->read_buffer_length
;
89 /* There is room in the buffer, try to fill it! */
90 if (ptr
->read_buffer_length
!= MEMCACHED_MAX_BUFFER
)
92 /* Just try a single read to grab what's available */
93 ssize_t nr
= read(ptr
->fd
,
94 ptr
->read_ptr
+ ptr
->read_data_length
,
95 MEMCACHED_MAX_BUFFER
- ptr
->read_data_length
);
99 ptr
->read_data_length
+= (size_t)nr
;
100 ptr
->read_buffer_length
+= (size_t)nr
;
108 * If the we have callbacks connected to this server structure
109 * we may start process the input queue and fire the callbacks
110 * for the incomming messages. This function is _only_ called
111 * when the input buffer is full, so that we _know_ that we have
112 * at least _one_ message to process.
114 * @param ptr the server to star processing iput messages for
115 * @return true if we processed anything, false otherwise
117 static bool process_input_buffer(memcached_server_st
*ptr
)
120 ** We might be able to process some of the response messages if we
121 ** have a callback set up
123 if (ptr
->root
->callbacks
!= NULL
&& ptr
->root
->flags
.use_udp
== false)
126 * We might have responses... try to read them out and fire
129 memcached_callback_st cb
= *ptr
->root
->callbacks
;
131 char buffer
[MEMCACHED_DEFAULT_COMMAND_SIZE
];
132 memcached_return_t error
;
133 error
= memcached_response(ptr
, buffer
, sizeof(buffer
),
135 if (error
== MEMCACHED_SUCCESS
)
137 for (unsigned int x
= 0; x
< cb
.number_of_callback
; x
++)
139 error
= (*cb
.callback
[x
])(ptr
->root
, &ptr
->root
->result
, cb
.context
);
140 if (error
!= MEMCACHED_SUCCESS
)
144 /* @todo what should I do with the error message??? */
146 /* @todo what should I do with other error messages?? */
154 void memcached_io_preread(memcached_st
*ptr
)
160 for (x
= 0; x
< ptr
->number_of_hosts
; x
++)
162 if (memcached_server_response_count(ptr
, x
) &&
163 ptr
->hosts
[x
].read_data_length
< MEMCACHED_MAX_BUFFER
)
167 data_read
= read(ptr
->hosts
[x
].fd
,
168 ptr
->hosts
[x
].read_ptr
+ ptr
->hosts
[x
].read_data_length
,
169 MEMCACHED_MAX_BUFFER
- ptr
->hosts
[x
].read_data_length
);
173 ptr
->hosts
[x
].read_buffer_length
+= data_read
;
174 ptr
->hosts
[x
].read_data_length
+= data_read
;
180 memcached_return_t
memcached_io_read(memcached_server_st
*ptr
,
181 void *buffer
, size_t length
, ssize_t
*nread
)
189 if (!ptr
->read_buffer_length
)
195 data_read
= read(ptr
->fd
, ptr
->read_buffer
, MEMCACHED_MAX_BUFFER
);
198 else if (data_read
== -1)
200 ptr
->cached_errno
= errno
;
201 memcached_return_t rc
= MEMCACHED_UNKNOWN_READ_FAILURE
;
206 if ((rc
= io_wait(ptr
, MEM_READ
)) == MEMCACHED_SUCCESS
)
212 memcached_quit_server(ptr
, 1);
221 EOF. Any data received so far is incomplete
222 so discard it. This always reads by byte in case of TCP
223 and protocol enforcement happens at memcached_response()
224 looking for '\n'. We do not care for UDB which requests 8 bytes
225 at once. Generally, this means that connection went away. Since
226 for blocking I/O we do not return 0 and for non-blocking case
227 it will return EGAIN if data is not immediatly available.
229 memcached_quit_server(ptr
, 1);
231 return MEMCACHED_UNKNOWN_READ_FAILURE
;
235 ptr
->io_bytes_sent
= 0;
236 ptr
->read_data_length
= (size_t) data_read
;
237 ptr
->read_buffer_length
= (size_t) data_read
;
238 ptr
->read_ptr
= ptr
->read_buffer
;
245 difference
= (length
> ptr
->read_buffer_length
) ? ptr
->read_buffer_length
: length
;
247 memcpy(buffer_ptr
, ptr
->read_ptr
, difference
);
248 length
-= difference
;
249 ptr
->read_ptr
+= difference
;
250 ptr
->read_buffer_length
-= difference
;
251 buffer_ptr
+= difference
;
255 *buffer_ptr
= *ptr
->read_ptr
;
257 ptr
->read_buffer_length
--;
263 ptr
->server_failure_counter
= 0;
264 *nread
= (ssize_t
)(buffer_ptr
- (char*)buffer
);
265 return MEMCACHED_SUCCESS
;
268 ssize_t
memcached_io_write(memcached_server_st
*ptr
,
269 const void *buffer
, size_t length
, char with_flush
)
271 size_t original_length
;
272 const char* buffer_ptr
;
274 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
276 original_length
= length
;
285 if (ptr
->type
== MEMCACHED_CONNECTION_UDP
)
287 //UDP does not support partial writes
288 buffer_end
= MAX_UDP_DATAGRAM_LENGTH
;
289 should_write
= length
;
290 if (ptr
->write_buffer_offset
+ should_write
> buffer_end
)
295 buffer_end
= MEMCACHED_MAX_BUFFER
;
296 should_write
= buffer_end
- ptr
->write_buffer_offset
;
297 should_write
= (should_write
< length
) ? should_write
: length
;
300 write_ptr
= ptr
->write_buffer
+ ptr
->write_buffer_offset
;
301 memcpy(write_ptr
, buffer_ptr
, should_write
);
302 ptr
->write_buffer_offset
+= should_write
;
303 buffer_ptr
+= should_write
;
304 length
-= should_write
;
306 if (ptr
->write_buffer_offset
== buffer_end
&& ptr
->type
!= MEMCACHED_CONNECTION_UDP
)
308 memcached_return_t rc
;
311 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
312 sent_length
= io_flush(ptr
, &rc
);
313 if (sent_length
== -1)
316 /* If io_flush calls memcached_purge, sent_length may be 0 */
317 unlikely (sent_length
!= 0)
319 WATCHPOINT_ASSERT(sent_length
== (ssize_t
)buffer_end
);
326 memcached_return_t rc
;
327 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
328 if (io_flush(ptr
, &rc
) == -1)
332 return (ssize_t
) original_length
;
335 memcached_return_t
memcached_io_close(memcached_server_st
*ptr
)
340 return MEMCACHED_SUCCESS
;
342 /* in case of death shutdown to avoid blocking at close() */
345 r
= shutdown(ptr
->fd
, SHUT_RDWR
);
348 if (r
&& errno
!= ENOTCONN
)
350 WATCHPOINT_NUMBER(ptr
->fd
);
351 WATCHPOINT_ERRNO(errno
);
352 WATCHPOINT_ASSERT(errno
);
360 WATCHPOINT_ERRNO(errno
);
363 return MEMCACHED_SUCCESS
;
366 memcached_server_st
*memcached_io_get_readable_server(memcached_st
*memc
)
368 #define MAX_SERVERS_TO_POLL 100
369 struct pollfd fds
[MAX_SERVERS_TO_POLL
];
370 unsigned int host_index
= 0;
372 for (unsigned int x
= 0;
373 x
< memc
->number_of_hosts
&& host_index
< MAX_SERVERS_TO_POLL
;
376 if (memc
->hosts
[x
].read_buffer_length
> 0) /* I have data in the buffer */
377 return &memc
->hosts
[x
];
379 if (memcached_server_response_count(&memc
->hosts
[x
]) > 0)
381 fds
[host_index
].events
= POLLIN
;
382 fds
[host_index
].revents
= 0;
383 fds
[host_index
].fd
= memc
->hosts
[x
].fd
;
390 /* We have 0 or 1 server with pending events.. */
391 for (unsigned int x
= 0; x
< memc
->number_of_hosts
; ++x
)
392 if (memcached_server_response_count(&memc
->hosts
[x
]) > 0)
393 return &memc
->hosts
[x
];
398 int err
= poll(fds
, host_index
, memc
->poll_timeout
);
401 memc
->cached_errno
= errno
;
406 for (unsigned int x
= 0; x
< host_index
; ++x
)
407 if (fds
[x
].revents
& POLLIN
)
408 for (unsigned int y
= 0; y
< memc
->number_of_hosts
; ++y
)
409 if (memc
->hosts
[y
].fd
== fds
[x
].fd
)
410 return &memc
->hosts
[y
];
416 static ssize_t
io_flush(memcached_server_st
*ptr
,
417 memcached_return_t
*error
)
420 ** We might want to purge the input buffer if we haven't consumed
421 ** any output yet... The test for the limits is the purge is inline
422 ** in the purge function to avoid duplicating the logic..
425 memcached_return_t rc
;
426 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
427 rc
= memcached_purge(ptr
);
429 if (rc
!= MEMCACHED_SUCCESS
&& rc
!= MEMCACHED_STORED
)
433 size_t return_length
;
434 char *local_write_ptr
= ptr
->write_buffer
;
435 size_t write_length
= ptr
->write_buffer_offset
;
437 *error
= MEMCACHED_SUCCESS
;
439 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
441 // UDP Sanity check, make sure that we are not sending somthing too big
442 if (ptr
->type
== MEMCACHED_CONNECTION_UDP
&& write_length
> MAX_UDP_DATAGRAM_LENGTH
)
445 if (ptr
->write_buffer_offset
== 0 || (ptr
->type
== MEMCACHED_CONNECTION_UDP
446 && ptr
->write_buffer_offset
== UDP_DATAGRAM_HEADER_LENGTH
))
449 /* Looking for memory overflows */
451 if (write_length
== MEMCACHED_MAX_BUFFER
)
452 WATCHPOINT_ASSERT(ptr
->write_buffer
== local_write_ptr
);
453 WATCHPOINT_ASSERT((ptr
->write_buffer
+ MEMCACHED_MAX_BUFFER
) >= (local_write_ptr
+ write_length
));
459 WATCHPOINT_ASSERT(ptr
->fd
!= -1);
460 WATCHPOINT_ASSERT(write_length
> 0);
462 if (ptr
->type
== MEMCACHED_CONNECTION_UDP
)
463 increment_udp_message_id(ptr
);
464 sent_length
= write(ptr
->fd
, local_write_ptr
, write_length
);
466 if (sent_length
== -1)
468 ptr
->cached_errno
= errno
;
476 * We may be blocked on write because the input buffer
477 * is full. Let's check if we have room in our input
478 * buffer for more data and retry the write before
481 if (repack_input_buffer(ptr
) ||
482 process_input_buffer(ptr
))
485 memcached_return_t rc
;
486 rc
= io_wait(ptr
, MEM_WRITE
);
488 if (rc
== MEMCACHED_SUCCESS
|| rc
== MEMCACHED_TIMEOUT
)
491 memcached_quit_server(ptr
, 1);
495 memcached_quit_server(ptr
, 1);
496 *error
= MEMCACHED_ERRNO
;
501 if (ptr
->type
== MEMCACHED_CONNECTION_UDP
&&
502 (size_t)sent_length
!= write_length
)
504 memcached_quit_server(ptr
, 1);
508 ptr
->io_bytes_sent
+= (uint32_t) sent_length
;
510 local_write_ptr
+= sent_length
;
511 write_length
-= (uint32_t) sent_length
;
512 return_length
+= (uint32_t) sent_length
;
515 WATCHPOINT_ASSERT(write_length
== 0);
516 // Need to study this assert() WATCHPOINT_ASSERT(return_length ==
517 // ptr->write_buffer_offset);
519 // if we are a udp server, the begining of the buffer is reserverd for
520 // the upd frame header
521 if (ptr
->type
== MEMCACHED_CONNECTION_UDP
)
522 ptr
->write_buffer_offset
= UDP_DATAGRAM_HEADER_LENGTH
;
524 ptr
->write_buffer_offset
= 0;
526 return (ssize_t
) return_length
;
530 Eventually we will just kill off the server with the problem.
532 void memcached_io_reset(memcached_server_st
*ptr
)
534 memcached_quit_server(ptr
, 1);
538 * Read a given number of bytes from the server and place it into a specific
539 * buffer. Reset the IO channel on this server if an error occurs.
541 memcached_return_t
memcached_safe_read(memcached_server_st
*ptr
,
548 while (offset
< size
)
551 memcached_return_t rc
= memcached_io_read(ptr
, data
+ offset
, size
- offset
,
553 if (rc
!= MEMCACHED_SUCCESS
)
556 offset
+= (size_t) nread
;
559 return MEMCACHED_SUCCESS
;
562 memcached_return_t
memcached_io_readline(memcached_server_st
*ptr
,
566 bool line_complete
= false;
569 while (!line_complete
)
571 if (ptr
->read_buffer_length
== 0)
574 * We don't have any data in the buffer, so let's fill the read
575 * buffer. Call the standard read function to avoid duplicating
579 memcached_return_t rc
= memcached_io_read(ptr
, buffer_ptr
, 1, &nread
);
580 if (rc
!= MEMCACHED_SUCCESS
)
583 if (*buffer_ptr
== '\n')
590 /* Now let's look in the buffer and copy as we go! */
591 while (ptr
->read_buffer_length
&& total_nr
< size
&& !line_complete
)
593 *buffer_ptr
= *ptr
->read_ptr
;
594 if (*buffer_ptr
== '\n')
595 line_complete
= true;
596 --ptr
->read_buffer_length
;
602 if (total_nr
== size
)
603 return MEMCACHED_PROTOCOL_ERROR
;
606 return MEMCACHED_SUCCESS
;
610 * The udp request id consists of two seperate sections
612 * 2) The message number
613 * The thread id should only be set when the memcached_st struct is created
614 * and should not be changed.
616 * The message num is incremented for each new message we send, this function
617 * extracts the message number from message_id, increments it and then
618 * writes the new value back into the header
620 static void increment_udp_message_id(memcached_server_st
*ptr
)
622 struct udp_datagram_header_st
*header
= (struct udp_datagram_header_st
*)ptr
->write_buffer
;
623 uint16_t cur_req
= get_udp_datagram_request_id(header
);
624 int msg_num
= get_msg_num_from_request_id(cur_req
);
625 int thread_id
= get_thread_id_from_request_id(cur_req
);
627 if (((++msg_num
) & UDP_REQUEST_ID_THREAD_MASK
) != 0)
630 header
->request_id
= htons((uint16_t) (thread_id
| msg_num
));
633 memcached_return_t
memcached_io_init_udp_header(memcached_server_st
*ptr
, uint16_t thread_id
)
635 if (thread_id
> UDP_REQUEST_ID_MAX_THREAD_ID
)
636 return MEMCACHED_FAILURE
;
638 struct udp_datagram_header_st
*header
= (struct udp_datagram_header_st
*)ptr
->write_buffer
;
639 header
->request_id
= htons((uint16_t) (generate_udp_request_thread_id(thread_id
)));
640 header
->num_datagrams
= htons(1);
641 header
->sequence_number
= htons(0);
643 return MEMCACHED_SUCCESS
;