d09f640daa681c1f2075e4481a54ff6f1b1fc8dd
1 /*****************************************************************************
2 * RRDtool 1.3.2 Copyright by Tobi Oetiker, 1997-2008
3 *****************************************************************************
4 * rrd_open.c Open an RRD File
5 *****************************************************************************
6 * $Id$
7 *****************************************************************************/
9 #ifdef WIN32
10 #include <stdlib.h>
11 #include <fcntl.h>
12 #include <sys/stat.h>
13 #endif
15 #ifdef HAVE_BROKEN_MS_ASYNC
16 #include <sys/types.h>
17 #include <utime.h>
18 #endif
20 #include "rrd_tool.h"
21 #include "unused.h"
22 #define MEMBLK 8192
24 #ifdef WIN32
25 #define _LK_UNLCK 0 /* Unlock */
26 #define _LK_LOCK 1 /* Lock */
27 #define _LK_NBLCK 2 /* Non-blocking lock */
28 #define _LK_RLCK 3 /* Lock for read only */
29 #define _LK_NBRLCK 4 /* Non-blocking lock for read only */
32 #define LK_UNLCK _LK_UNLCK
33 #define LK_LOCK _LK_LOCK
34 #define LK_NBLCK _LK_NBLCK
35 #define LK_RLCK _LK_RLCK
36 #define LK_NBRLCK _LK_NBRLCK
37 #endif
39 /* DEBUG 2 prints information obtained via mincore(2) */
40 #define DEBUG 1
41 /* do not calculate exact madvise hints but assume 1 page for headers and
42 * set DONTNEED for the rest, which is assumed to be data */
43 /* Avoid calling madvise on areas that were already hinted. May be benefical if
44 * your syscalls are very slow */
46 #ifdef HAVE_MMAP
47 /* the cast to void* is there to avoid this warning seen on ia64 with certain
48 versions of gcc: 'cast increases required alignment of target type'
49 */
50 #define __rrd_read(dst, dst_t, cnt) { \
51 size_t wanted = sizeof(dst_t)*(cnt); \
52 if (offset + wanted > rrd_file->file_len) { \
53 rrd_set_error("reached EOF while loading header " #dst); \
54 goto out_nullify_head; \
55 } \
56 (dst) = (dst_t*)(void*) (data + offset); \
57 offset += wanted; \
58 }
59 #else
60 #define __rrd_read(dst, dst_t, cnt) { \
61 size_t wanted = sizeof(dst_t)*(cnt); \
62 size_t got; \
63 if ((dst = (dst_t*)malloc(wanted)) == NULL) { \
64 rrd_set_error(#dst " malloc"); \
65 goto out_nullify_head; \
66 } \
67 got = read (rrd_simple_file->fd, dst, wanted); \
68 if (got != wanted) { \
69 rrd_set_error("short read while reading header " #dst); \
70 goto out_nullify_head; \
71 } \
72 offset += got; \
73 }
74 #endif
76 /* get the address of the start of this page */
77 #if defined USE_MADVISE || defined HAVE_POSIX_FADVISE
78 #ifndef PAGE_START
79 #define PAGE_START(addr) ((addr)&(~(_page_size-1)))
80 #endif
81 #endif
83 /* Open a database file, return its header and an open filehandle,
84 * positioned to the first cdp in the first rra.
85 * In the error path of rrd_open, only rrd_free(&rrd) has to be called
86 * before returning an error. Do not call rrd_close upon failure of rrd_open.
87 * If creating a new file, the parameter rrd must be initialised with
88 * details of the file content.
89 * If opening an existing file, then use rrd must be initialised by
90 * rrd_init(rrd) prior to invoking rrd_open
91 */
93 rrd_file_t *rrd_open(
94 const char *const file_name,
95 rrd_t *rrd,
96 unsigned rdwr)
97 {
98 unsigned long ui;
99 int flags = 0;
100 int version;
102 #ifdef HAVE_MMAP
103 ssize_t _page_size = sysconf(_SC_PAGESIZE);
104 char *data = MAP_FAILED;
105 #endif
106 off_t offset = 0;
107 struct stat statb;
108 rrd_file_t *rrd_file = NULL;
109 rrd_simple_file_t *rrd_simple_file = NULL;
110 size_t newfile_size = 0;
111 size_t header_len, value_cnt, data_len;
113 /* Are we creating a new file? */
114 if((rdwr & RRD_CREAT) && (rrd->stat_head != NULL))
115 {
116 header_len = rrd_get_header_size(rrd);
118 value_cnt = 0;
119 for (ui = 0; ui < rrd->stat_head->rra_cnt; ui++)
120 value_cnt += rrd->stat_head->ds_cnt * rrd->rra_def[ui].row_cnt;
122 data_len = sizeof(rrd_value_t) * value_cnt;
124 newfile_size = header_len + data_len;
125 }
127 rrd_file = (rrd_file_t*)malloc(sizeof(rrd_file_t));
128 if (rrd_file == NULL) {
129 rrd_set_error("allocating rrd_file descriptor for '%s'", file_name);
130 return NULL;
131 }
132 memset(rrd_file, 0, sizeof(rrd_file_t));
134 rrd_file->pvt = malloc(sizeof(rrd_simple_file_t));
135 if(rrd_file->pvt == NULL) {
136 rrd_set_error("allocating rrd_simple_file for '%s'", file_name);
137 return NULL;
138 }
139 memset(rrd_file->pvt, 0, sizeof(rrd_simple_file_t));
140 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
142 #ifdef DEBUG
143 if ((rdwr & (RRD_READONLY | RRD_READWRITE)) ==
144 (RRD_READONLY | RRD_READWRITE)) {
145 /* Both READONLY and READWRITE were given, which is invalid. */
146 rrd_set_error("in read/write request mask");
147 exit(-1);
148 }
149 #endif
151 #ifdef HAVE_MMAP
152 rrd_simple_file->mm_prot = PROT_READ;
153 rrd_simple_file->mm_flags = 0;
154 #endif
156 if (rdwr & RRD_READONLY) {
157 flags |= O_RDONLY;
158 #ifdef HAVE_MMAP
159 rrd_simple_file->mm_flags = MAP_PRIVATE;
160 # ifdef MAP_NORESERVE
161 rrd_simple_file->mm_flags |= MAP_NORESERVE; /* readonly, so no swap backing needed */
162 # endif
163 #endif
164 } else {
165 if (rdwr & RRD_READWRITE) {
166 flags |= O_RDWR;
167 #ifdef HAVE_MMAP
168 rrd_simple_file->mm_flags = MAP_SHARED;
169 rrd_simple_file->mm_prot |= PROT_WRITE;
170 #endif
171 }
172 if (rdwr & RRD_CREAT) {
173 flags |= (O_CREAT | O_TRUNC);
174 }
175 }
176 if (rdwr & RRD_READAHEAD) {
177 #ifdef MAP_POPULATE
178 rrd_simple_file->mm_flags |= MAP_POPULATE; /* populate ptes and data */
179 #endif
180 #if defined MAP_NONBLOCK
181 rrd_simple_file->mm_flags |= MAP_NONBLOCK; /* just populate ptes */
182 #endif
183 }
184 #if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
185 flags |= O_BINARY;
186 #endif
188 if ((rrd_simple_file->fd = open(file_name, flags, 0666)) < 0) {
189 rrd_set_error("opening '%s': %s", file_name, rrd_strerror(errno));
190 goto out_free;
191 }
193 #ifdef HAVE_MMAP
194 #ifdef HAVE_BROKEN_MS_ASYNC
195 if (rdwr & RRD_READWRITE) {
196 /* some unices, the files mtime does not get update
197 on msync MS_ASYNC, in order to help them,
198 we update the the timestamp at this point.
199 The thing happens pretty 'close' to the open
200 call so the chances of a race should be minimal.
202 Maybe ask your vendor to fix your OS ... */
203 utime(file_name,NULL);
204 }
205 #endif
206 #endif
208 /* Better try to avoid seeks as much as possible. stat may be heavy but
209 * many concurrent seeks are even worse. */
210 if (newfile_size == 0 && ((fstat(rrd_simple_file->fd, &statb)) < 0)) {
211 rrd_set_error("fstat '%s': %s", file_name, rrd_strerror(errno));
212 goto out_close;
213 }
214 if (newfile_size == 0) {
215 rrd_file->file_len = statb.st_size;
216 } else {
217 rrd_file->file_len = newfile_size;
218 lseek(rrd_simple_file->fd, newfile_size - 1, SEEK_SET);
219 write(rrd_simple_file->fd, "\0", 1); /* poke */
220 lseek(rrd_simple_file->fd, 0, SEEK_SET);
221 }
222 #ifdef HAVE_POSIX_FADVISE
223 /* In general we need no read-ahead when dealing with rrd_files.
224 When we stop reading, it is highly unlikely that we start up again.
225 In this manner we actually save time and diskaccess (and buffer cache).
226 Thanks to Dave Plonka for the Idea of using POSIX_FADV_RANDOM here. */
227 posix_fadvise(rrd_simple_file->fd, 0, 0, POSIX_FADV_RANDOM);
228 #endif
230 /*
231 if (rdwr & RRD_READWRITE)
232 {
233 if (setvbuf((rrd_simple_file->fd),NULL,_IONBF,2)) {
234 rrd_set_error("failed to disable the stream buffer\n");
235 return (-1);
236 }
237 }
238 */
240 #ifdef HAVE_MMAP
241 data = mmap(0, rrd_file->file_len,
242 rrd_simple_file->mm_prot, rrd_simple_file->mm_flags,
243 rrd_simple_file->fd, offset);
245 /* lets see if the first read worked */
246 if (data == MAP_FAILED) {
247 rrd_set_error("mmaping file '%s': %s", file_name,
248 rrd_strerror(errno));
249 goto out_close;
250 }
251 rrd_simple_file->file_start = data;
252 if (rdwr & RRD_CREAT) {
253 memset(data, DNAN, newfile_size - 1);
254 goto out_done;
255 }
256 #endif
257 if (rdwr & RRD_CREAT)
258 goto out_done;
259 #ifdef USE_MADVISE
260 if (rdwr & RRD_COPY) {
261 /* We will read everything in a moment (copying) */
262 madvise(data, rrd_file->file_len, MADV_WILLNEED );
263 madvise(data, rrd_file->file_len, MADV_SEQUENTIAL );
264 } else {
265 /* We do not need to read anything in for the moment */
266 madvise(data, rrd_file->file_len, MADV_RANDOM);
267 /* the stat_head will be needed soonish, so hint accordingly */
268 madvise(data, sizeof(stat_head_t), MADV_WILLNEED);
269 madvise(data, sizeof(stat_head_t), MADV_RANDOM);
270 }
271 #endif
273 __rrd_read(rrd->stat_head, stat_head_t,
274 1);
276 /* lets do some test if we are on track ... */
277 if (memcmp(rrd->stat_head->cookie, RRD_COOKIE, sizeof(RRD_COOKIE)) != 0) {
278 rrd_set_error("'%s' is not an RRD file", file_name);
279 goto out_nullify_head;
280 }
282 if (rrd->stat_head->float_cookie != FLOAT_COOKIE) {
283 rrd_set_error("This RRD was created on another architecture");
284 goto out_nullify_head;
285 }
287 version = atoi(rrd->stat_head->version);
289 if (version > atoi(RRD_VERSION)) {
290 rrd_set_error("can't handle RRD file version %s",
291 rrd->stat_head->version);
292 goto out_nullify_head;
293 }
294 #if defined USE_MADVISE
295 /* the ds_def will be needed soonish, so hint accordingly */
296 madvise(data + PAGE_START(offset),
297 sizeof(ds_def_t) * rrd->stat_head->ds_cnt, MADV_WILLNEED);
298 #endif
299 __rrd_read(rrd->ds_def, ds_def_t,
300 rrd->stat_head->ds_cnt);
302 #if defined USE_MADVISE
303 /* the rra_def will be needed soonish, so hint accordingly */
304 madvise(data + PAGE_START(offset),
305 sizeof(rra_def_t) * rrd->stat_head->rra_cnt, MADV_WILLNEED);
306 #endif
307 __rrd_read(rrd->rra_def, rra_def_t,
308 rrd->stat_head->rra_cnt);
310 /* handle different format for the live_head */
311 if (version < 3) {
312 rrd->live_head = (live_head_t *) malloc(sizeof(live_head_t));
313 if (rrd->live_head == NULL) {
314 rrd_set_error("live_head_t malloc");
315 goto out_close;
316 }
317 #if defined USE_MADVISE
318 /* the live_head will be needed soonish, so hint accordingly */
319 madvise(data + PAGE_START(offset), sizeof(time_t), MADV_WILLNEED);
320 #endif
321 __rrd_read(rrd->legacy_last_up, time_t,
322 1);
324 rrd->live_head->last_up = *rrd->legacy_last_up;
325 rrd->live_head->last_up_usec = 0;
326 } else {
327 #if defined USE_MADVISE
328 /* the live_head will be needed soonish, so hint accordingly */
329 madvise(data + PAGE_START(offset),
330 sizeof(live_head_t), MADV_WILLNEED);
331 #endif
332 __rrd_read(rrd->live_head, live_head_t,
333 1);
334 }
335 __rrd_read(rrd->pdp_prep, pdp_prep_t,
336 rrd->stat_head->ds_cnt);
337 __rrd_read(rrd->cdp_prep, cdp_prep_t,
338 rrd->stat_head->rra_cnt * rrd->stat_head->ds_cnt);
339 __rrd_read(rrd->rra_ptr, rra_ptr_t,
340 rrd->stat_head->rra_cnt);
342 rrd_file->header_len = offset;
343 rrd_file->pos = offset;
345 {
346 unsigned long row_cnt = 0;
348 for (ui=0; ui<rrd->stat_head->rra_cnt; ui++)
349 row_cnt += rrd->rra_def[ui].row_cnt;
351 size_t correct_len = rrd_file->header_len +
352 sizeof(rrd_value_t) * row_cnt * rrd->stat_head->ds_cnt;
354 if (correct_len > rrd_file->file_len)
355 {
356 rrd_set_error("'%s' is too small (should be %ld bytes)",
357 file_name, (long long) correct_len);
358 goto out_nullify_head;
359 }
360 }
362 out_done:
363 return (rrd_file);
364 out_nullify_head:
365 rrd->stat_head = NULL;
366 out_close:
367 #ifdef HAVE_MMAP
368 if (data != MAP_FAILED)
369 munmap(data, rrd_file->file_len);
370 #endif
372 close(rrd_simple_file->fd);
373 out_free:
374 free(rrd_file->pvt);
375 free(rrd_file);
376 return NULL;
377 }
380 #if defined DEBUG && DEBUG > 1
381 /* Print list of in-core pages of a the current rrd_file. */
382 static
383 void mincore_print(
384 rrd_file_t *rrd_file,
385 char *mark)
386 {
387 rrd_simple_file_t *rrd_simple_file;
388 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
389 #ifdef HAVE_MMAP
390 /* pretty print blocks in core */
391 size_t off;
392 unsigned char *vec;
393 ssize_t _page_size = sysconf(_SC_PAGESIZE);
395 off = rrd_file->file_len +
396 ((rrd_file->file_len + _page_size - 1) / _page_size);
397 vec = malloc(off);
398 if (vec != NULL) {
399 memset(vec, 0, off);
400 if (mincore(rrd_simple_file->file_start, rrd_file->file_len, vec) == 0) {
401 int prev;
402 unsigned is_in = 0, was_in = 0;
404 for (off = 0, prev = 0; off < rrd_file->file_len; ++off) {
405 is_in = vec[off] & 1; /* if lsb set then is core resident */
406 if (off == 0)
407 was_in = is_in;
408 if (was_in != is_in) {
409 fprintf(stderr, "%s: %sin core: %p len %ld\n", mark,
410 was_in ? "" : "not ", vec + prev, off - prev);
411 was_in = is_in;
412 prev = off;
413 }
414 }
415 fprintf(stderr,
416 "%s: %sin core: %p len %ld\n", mark,
417 was_in ? "" : "not ", vec + prev, off - prev);
418 } else
419 fprintf(stderr, "mincore: %s", rrd_strerror(errno));
420 }
421 #else
422 fprintf(stderr, "sorry mincore only works with mmap");
423 #endif
424 }
425 #endif /* defined DEBUG && DEBUG > 1 */
427 /*
428 * get exclusive lock to whole file.
429 * lock gets removed when we close the file
430 *
431 * returns 0 on success
432 */
433 int rrd_lock(
434 rrd_file_t *rrd_file)
435 {
436 int rcstat;
437 rrd_simple_file_t *rrd_simple_file;
438 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
440 {
441 #if defined(_WIN32) && !defined(__CYGWIN__) && !defined(__CYGWIN32__)
442 struct _stat st;
444 if (_fstat(rrd_simple_file->fd, &st) == 0) {
445 rcstat = _locking(rrd_simple_file->fd, _LK_NBLCK, st.st_size);
446 } else {
447 rcstat = -1;
448 }
449 #else
450 struct flock lock;
452 lock.l_type = F_WRLCK; /* exclusive write lock */
453 lock.l_len = 0; /* whole file */
454 lock.l_start = 0; /* start of file */
455 lock.l_whence = SEEK_SET; /* end of file */
457 rcstat = fcntl(rrd_simple_file->fd, F_SETLK, &lock);
458 #endif
459 }
461 return (rcstat);
462 }
465 /* drop cache except for the header and the active pages */
466 void rrd_dontneed(
467 rrd_file_t *rrd_file,
468 rrd_t *rrd)
469 {
470 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
471 #if defined USE_MADVISE || defined HAVE_POSIX_FADVISE
472 size_t dontneed_start;
473 size_t rra_start;
474 size_t active_block;
475 size_t i;
476 ssize_t _page_size = sysconf(_SC_PAGESIZE);
478 if (rrd_file == NULL) {
479 #if defined DEBUG && DEBUG
480 fprintf (stderr, "rrd_dontneed: Argument 'rrd_file' is NULL.\n");
481 #endif
482 return;
483 }
485 #if defined DEBUG && DEBUG > 1
486 mincore_print(rrd_file, "before");
487 #endif
489 /* ignoring errors from RRDs that are smaller then the file_len+rounding */
490 rra_start = rrd_file->header_len;
491 dontneed_start = PAGE_START(rra_start) + _page_size;
492 for (i = 0; i < rrd->stat_head->rra_cnt; ++i) {
493 active_block =
494 PAGE_START(rra_start
495 + rrd->rra_ptr[i].cur_row
496 * rrd->stat_head->ds_cnt * sizeof(rrd_value_t));
497 if (active_block > dontneed_start) {
498 #ifdef USE_MADVISE
499 madvise(rrd_simple_file->file_start + dontneed_start,
500 active_block - dontneed_start - 1, MADV_DONTNEED);
501 #endif
502 /* in linux at least only fadvise DONTNEED seems to purge pages from cache */
503 #ifdef HAVE_POSIX_FADVISE
504 posix_fadvise(rrd_simple_file->fd, dontneed_start,
505 active_block - dontneed_start - 1,
506 POSIX_FADV_DONTNEED);
507 #endif
508 }
509 dontneed_start = active_block;
510 /* do not release 'hot' block if update for this RAA will occur
511 * within 10 minutes */
512 if (rrd->stat_head->pdp_step * rrd->rra_def[i].pdp_cnt -
513 rrd->live_head->last_up % (rrd->stat_head->pdp_step *
514 rrd->rra_def[i].pdp_cnt) < 10 * 60) {
515 dontneed_start += _page_size;
516 }
517 rra_start +=
518 rrd->rra_def[i].row_cnt * rrd->stat_head->ds_cnt *
519 sizeof(rrd_value_t);
520 }
522 if (dontneed_start < rrd_file->file_len) {
523 #ifdef USE_MADVISE
524 madvise(rrd_simple_file->file_start + dontneed_start,
525 rrd_file->file_len - dontneed_start, MADV_DONTNEED);
526 #endif
527 #ifdef HAVE_POSIX_FADVISE
528 posix_fadvise(rrd_simple_file->fd, dontneed_start,
529 rrd_file->file_len - dontneed_start,
530 POSIX_FADV_DONTNEED);
531 #endif
532 }
534 #if defined DEBUG && DEBUG > 1
535 mincore_print(rrd_file, "after");
536 #endif
537 #endif /* without madvise and posix_fadvise it does not make much sense todo anything */
538 }
544 int rrd_close(
545 rrd_file_t *rrd_file)
546 {
547 rrd_simple_file_t *rrd_simple_file;
548 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
549 int ret;
551 #ifdef HAVE_MMAP
552 ret = msync(rrd_simple_file->file_start, rrd_file->file_len, MS_ASYNC);
553 if (ret != 0)
554 rrd_set_error("msync rrd_file: %s", rrd_strerror(errno));
555 ret = munmap(rrd_simple_file->file_start, rrd_file->file_len);
556 if (ret != 0)
557 rrd_set_error("munmap rrd_file: %s", rrd_strerror(errno));
558 #endif
559 ret = close(rrd_simple_file->fd);
560 if (ret != 0)
561 rrd_set_error("closing file: %s", rrd_strerror(errno));
562 free(rrd_file->pvt);
563 free(rrd_file);
564 rrd_file = NULL;
565 return ret;
566 }
569 /* Set position of rrd_file. */
571 off_t rrd_seek(
572 rrd_file_t *rrd_file,
573 off_t off,
574 int whence)
575 {
576 off_t ret = 0;
577 rrd_simple_file_t *rrd_simple_file;
578 rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
580 #ifdef HAVE_MMAP
581 if (whence == SEEK_SET)
582 rrd_file->pos = off;
583 else if (whence == SEEK_CUR)
584 rrd_file->pos += off;
585 else if (whence == SEEK_END)
586 rrd_file->pos = rrd_file->file_len + off;
587 #else
588 ret = lseek(rrd_simple_file->fd, off, whence);
589 if (ret < 0)
590 rrd_set_error("lseek: %s", rrd_strerror(errno));
591 rrd_file->pos = ret;
592 #endif
593 /* mimic fseek, which returns 0 upon success */
594 return ret < 0; /*XXX: or just ret to mimic lseek */
595 }
598 /* Get current position in rrd_file. */
600 off_t rrd_tell(
601 rrd_file_t *rrd_file)
602 {
603 return rrd_file->pos;
604 }
607 /* Read count bytes into buffer buf, starting at rrd_file->pos.
608 * Returns the number of bytes read or <0 on error. */
610 ssize_t rrd_read(
611 rrd_file_t *rrd_file,
612 void *buf,
613 size_t count)
614 {
615 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
616 #ifdef HAVE_MMAP
617 size_t _cnt = count;
618 ssize_t _surplus;
620 if (rrd_file->pos > rrd_file->file_len || _cnt == 0) /* EOF */
621 return 0;
622 if (buf == NULL)
623 return -1; /* EINVAL */
624 _surplus = rrd_file->pos + _cnt - rrd_file->file_len;
625 if (_surplus > 0) { /* short read */
626 _cnt -= _surplus;
627 }
628 if (_cnt == 0)
629 return 0; /* EOF */
630 buf = memcpy(buf, rrd_simple_file->file_start + rrd_file->pos, _cnt);
632 rrd_file->pos += _cnt; /* mimmic read() semantics */
633 return _cnt;
634 #else
635 ssize_t ret;
637 ret = read(rrd_simple_file->fd, buf, count);
638 if (ret > 0)
639 rrd_file->pos += ret; /* mimmic read() semantics */
640 return ret;
641 #endif
642 }
645 /* Write count bytes from buffer buf to the current position
646 * rrd_file->pos of rrd_simple_file->fd.
647 * Returns the number of bytes written or <0 on error. */
649 ssize_t rrd_write(
650 rrd_file_t *rrd_file,
651 const void *buf,
652 size_t count)
653 {
654 rrd_simple_file_t *rrd_simple_file = (rrd_simple_file_t *)rrd_file->pvt;
655 #ifdef HAVE_MMAP
656 size_t old_size = rrd_file->file_len;
657 if (count == 0)
658 return 0;
659 if (buf == NULL)
660 return -1; /* EINVAL */
662 if((rrd_file->pos + count) > old_size)
663 {
664 rrd_set_error("attempting to write beyond end of file");
665 return -1;
666 }
667 memcpy(rrd_simple_file->file_start + rrd_file->pos, buf, count);
668 rrd_file->pos += count;
669 return count; /* mimmic write() semantics */
670 #else
671 ssize_t _sz = write(rrd_simple_file->fd, buf, count);
673 if (_sz > 0)
674 rrd_file->pos += _sz;
675 return _sz;
676 #endif
677 }
680 /* this is a leftover from the old days, it serves no purpose
681 and is therefore turned into a no-op */
682 void rrd_flush(
683 rrd_file_t *rrd_file __attribute__((unused)))
684 {
685 }
687 /* Initialize RRD header. */
689 void rrd_init(
690 rrd_t *rrd)
691 {
692 rrd->stat_head = NULL;
693 rrd->ds_def = NULL;
694 rrd->rra_def = NULL;
695 rrd->live_head = NULL;
696 rrd->legacy_last_up = NULL;
697 rrd->rra_ptr = NULL;
698 rrd->pdp_prep = NULL;
699 rrd->cdp_prep = NULL;
700 rrd->rrd_value = NULL;
701 }
704 /* free RRD header data. */
706 #ifdef HAVE_MMAP
707 void rrd_free(
708 rrd_t *rrd)
709 {
710 if (rrd->legacy_last_up) { /* this gets set for version < 3 only */
711 free(rrd->live_head);
712 }
713 }
714 #else
715 void rrd_free(
716 rrd_t *rrd)
717 {
718 free(rrd->live_head);
719 free(rrd->stat_head);
720 free(rrd->ds_def);
721 free(rrd->rra_def);
722 free(rrd->rra_ptr);
723 free(rrd->pdp_prep);
724 free(rrd->cdp_prep);
725 free(rrd->rrd_value);
726 }
727 #endif
730 /* routine used by external libraries to free memory allocated by
731 * rrd library */
733 void rrd_freemem(
734 void *mem)
735 {
736 free(mem);
737 }
739 /*
740 * rra_update informs us about the RRAs being updated
741 * The low level storage API may use this information for
742 * aligning RRAs within stripes, or other performance enhancements
743 */
744 void rrd_notify_row(
745 rrd_file_t *rrd_file __attribute__((unused)),
746 int rra_idx __attribute__((unused)),
747 unsigned long rra_row __attribute__((unused)),
748 time_t rra_time __attribute__((unused)))
749 {
750 }
752 /*
753 * This function is called when creating a new RRD
754 * The storage implementation can use this opportunity to select
755 * a sensible starting row within the file.
756 * The default implementation is random, to ensure that all RRAs
757 * don't change to a new disk block at the same time
758 */
759 unsigned long rrd_select_initial_row(
760 rrd_file_t *rrd_file __attribute__((unused)),
761 int rra_idx __attribute__((unused)),
762 rra_def_t *rra
763 )
764 {
765 return rrd_random() % rra->row_cnt;
766 }