1librrd(3) rrdtool librrd(3)
2
6 librrd - RRD library functions
7
9 librrd contains most of the functionality in RRDtool. The command line
10 utilities and language bindings are often just wrappers around the code
11 contained in librrd.
12 This manual page documents the librrd API.
14 NOTE: This document is a work in progress, and should be considered
16 incomplete as long as this warning persists. For more information
17 about the librrd functions, always consult the source code.
18
20 rrd_dump_cb_r(char *filename, int opt_header, rrd_output_callback_t cb,
21 void *user)
22 In some situations it is necessary to get the output of "rrd_dump"
23 without writing it to a file or the standard output. In such cases
24 an application can ask rrd_dump_cb_r to call a user-defined
25 function each time there is output to be stored somewhere. This can
26 be used, to e.g. directly feed an XML parser with the dumped output
27 or transfer the resulting string in memory.
28 The arguments for rrd_dump_cb_r are the same as for rrd_dump_opt_r
30 except that the output filename parameter is replaced by the user-
31 defined callback function and an additional parameter for the
32 callback function that is passed untouched, i.e. to store
33 information about the callback state needed for the user-defined
34 callback to function properly.
35 Recent versions of rrd_dump_opt_r internally use this callback
37 mechanism to write their output to the file provided by the user.
38 size_t rrd_dump_opt_cb_fileout(
40 const void *data,
41 size_t len,
42 void *user)
43 {
44 return fwrite(data, 1, len, (FILE *)user);
45 }
46 The associated call for rrd_dump_cb_r looks like
48 res = rrd_dump_cb_r(filename, opt_header,
50 rrd_dump_opt_cb_fileout, (void *)out_file);
51 where the last parameter specifies the file handle
53 rrd_dump_opt_cb_fileout should write to. There's no specific
54 condition for the callback to detect when it is called for the
55 first time, nor for the last time. If you require this for
56 initialization and cleanup you should do those tasks before and
57 after calling rrd_dump_cb_r respectively.
58 rrd_fetch_cb_register(rrd_fetch_cb_t c)
60 If your data does not reside in rrd files, but you would like to
61 draw charts using the rrd_graph functionality, you can supply your
62 own rrd_fetch function and register it using the
63 rrd_fetch_cb_register function.
64 The argument signature and api must be the same of the callback
66 function and must be equivalent to the one of rrd_fetch_fn in
67 rrd_fetch.c.
68 To activate the callback function you can use the pseudo filename
70 cb//free_form_text.
71 Note that rrdtool graph will not ask the same rrd for data twice.
73 It determines this by building a key out of the values supplied to
74 the fetch function. If the values are the same, the previous answer
75 will be used.
76
78 rrd_random()
79 Generates random numbers just like random(). This further ensures
80 that the random number generator is seeded exactly once per
81 process.
82 rrd_strtodbl
84 an rrd aware string to double converter which sets rrd_error in if
85 there is a problem and uses the return code exclusively for
86 conversion status reporting.
87 rrd_strtod
89 works like normal strtod, but it is locale independent (and thread
90 safe)
91 rrd_snprintf
93 works like normal snprintf but it is locale independent (and
94 thread safe)
95 rrd_add_ptr(void ***dest, size_t *dest_size, void *src)
97 Dynamically resize the array pointed to by "dest". "dest_size" is
98 a pointer to the current size of "dest". Upon successful
99 realloc(), the "dest_size" is incremented by 1 and the "src"
100 pointer is stored at the end of the new "dest". Returns 1 on
101 success, 0 on failure.
102 type **arr = NULL;
104 type *elem = "whatever";
105 size_t arr_size = 0;
106 if (!rrd_add_ptr(&arr, &arr_size, elem))
107 handle_failure();
108 rrd_add_ptr_chunk(void ***dest, size_t *dest_size, void *src, size_t
110 *alloc, size_t chunk)
111 Like "rrd_add_ptr", except the destination is allocated in chunks
112 of "chunk". "alloc" points to the number of entries allocated,
113 whereas "dest_size" points to the number of valid pointers. If
114 more pointers are needed, "chunk" pointers are allocated and
115 "alloc" is increased accordingly. "alloc" must be >= "dest_size".
116 This method improves performance on hosts with expensive
118 "realloc()".
119 rrd_add_strdup(char ***dest, size_t *dest_size, char *src)
121 Like "rrd_add_ptr", except adds a "strdup" of the source string.
122 char **arr = NULL;
124 size_t arr_size = NULL;
125 char *str = "example text";
126 if (!rrd_add_strdup(&arr, &arr_size, str))
127 handle_failure();
128 rrd_add_strdup_chunk(char ***dest, size_t *dest_size, char *src, size_t
130 *alloc, size_t chunk)
131 Like "rrd_add_strdup", except the destination is allocated in
132 chunks of "chunk". "alloc" points to the number of entries
133 allocated, whereas "dest_size" points to the number of valid
134 pointers. If more pointers are needed, "chunk" pointers are
135 allocated and "alloc" is increased accordingly. "alloc" must be >=
136 "dest_size".
137 rrd_free_ptrs(void ***src, size_t *cnt)
139 Free an array of pointers allocated by "rrd_add_ptr" or
140 "rrd_add_strdup". Also frees the array pointer itself. On return,
141 the source pointer will be NULL and the count will be zero.
142 /* created as above */
144 rrd_free_ptrs(&arr, &arr_size);
145 /* here, arr == NULL && arr_size == 0 */
146 rrd_mkdir_p(const char *pathname, mode_t mode)
148 Create the directory named "pathname" including all of its parent
149 directories (similar to "mkdir -p" on the command line - see
150 mkdir(1) for more information). The argument "mode" specifies the
151 permissions to use. It is modified by the process's "umask". See
152 mkdir(2) for more details.
153 The function returns 0 on success, a negative value else. In case
155 of an error, "errno" is set accordingly. Aside from the errors
156 documented in mkdir(2), the function may fail with the following
157 errors:
158 EINVAL
160 "pathname" is "NULL" or the empty string.
161 ENOMEM
163 Insufficient memory was available.
164 any error returned by stat(2)
166 In contrast to mkdir(2), the function does not fail if "pathname"
168 already exists and is a directory.
169 rrd_scaled_duration (const char * token, unsigned long divisor,
171 unsigned long * valuep)
172 Parse a token in a context where it contains a count (of seconds or
173 PDP instances), or a duration that can be converted to a count by
174 representing the duration in seconds and dividing by some scaling
175 factor. For example, if a user would natively express a 3 day
176 archive of samples collected every 2 minutes, the sample interval
177 can be represented by "2m" instead of 120, and the archive duration
178 by "3d" (to be divided by 120) instead of 2160 (3*24*60*60 / 120).
179 See more examples in "STEP, HEARTBEAT, and Rows As Durations" in
180 rrdcreate.
181 "token" must be a number with an optional single-character suffix
183 encoding the scaling factor:
184 "s" indicates seconds
186 "m" indicates minutes. The value is multiplied by 60.
188 "h" indicates hours. The value is multiplied by 3600 (or "60m").
190 "d" indicates days. The value is multiplied by 86400 (or "24h").
192 "w" indicates weeks. The value is multiplied by 604800 (or "7d").
194 "M" indicates months. The value is multiplied by 2678400 (or
196 "31d"). (Note this factor accommodates the maximum number of
197 days in a month.)
198 "y" indicates years. The value is multiplied by 31622400 (or
200 "366d"). (Note this factor accommodates leap years.)
201 "divisor" is a positive value representing the duration in seconds
203 of an interval that the desired result counts.
204 "valuep" is a pointer to where the decoded value will be stored if
206 the conversion is successful.
207 The initial characters of "token" must be the base-10
209 representation of a positive integer, or the conversion fails.
210 If the remainder "token" is empty (no suffix), it is a count and no
212 scaling is performed.
213 If "token" has one of the suffixes above, the count is multiplied
215 to convert it to a duration in seconds. The resulting number of
216 seconds is divided by "divisor" to produce a count of intervals
217 each of duration "divisor" seconds. If division would produce a
218 remainder (e.g., "5m" (300 seconds) divided by "90s"), the
219 conversion is invalid.
220 If "token" has unrecognized trailing characters the conversion
222 fails.
223 The function returns a null pointer if the conversion was
225 successful and "valuep" has been updated to the scaled value. On
226 failure, it returns a text diagnostic suitable for use in user
227 error messages.
228
230 The following functions are used to connected to an rrdcached instance,
231 either via a unix or inet address, and create, update, or gather
232 statistics about a specified RRD database file.
233 There are two different interfaces: The rrd_client_ family of functions
235 operate on a user-provided client object (rrd_client_t) and support
236 multiple concurrent connections to rrdcache instances. The simpler
237 rrdc_ family of functions handles connections transparently but can
238 only be used for one connection at a time.
239 All of the following functions and data types are specified in the
241 "rrd_client.h" header file.
242 rrd_client_new(const char *daemon_addr)
244 Create a new client connection object. If specified, connect to the
245 daemon at "daemon_addr". The connection can later be changed by
246 calling rrd_client_connect.
247 rrd_client_destroy(rrd_client_t *client)
249 Close a client connection and destroy the object by freeing all
250 dynamically allocated memory. After calling this function, "client"
251 can no longer be used.
252 rrd_client_connect(rrd_client_t *client, const char *daemon_addr)
254 rrdc_connect(const char *daemon_addr)
255 Connect to a running rrdcached instance, specified via
256 "daemon_addr". Any previous connection will be closed. If
257 "daemon_addr" is "NULL", it defaults to the value of the
258 "ENV_RRDCACHED_ADDRESS" environment address.
259 rrd_client_is_connected(rrd_client_t *client)
261 Return a boolean int if the client is connected to the server.
262 rrd_client_address(rrd_client_t *client)
264 Returns the server address belonging to the current connection.
265 rrdc_is_connected(const char *daemon_addr)
267 Return a boolean int to determine if the client is connected to the
268 rrdcache daemon specified by the "daemon_addr" parameter.
269 rrd_client_ping(rrd_client_t *client)
271 rrdc_ping
272 Check the client connection by pinging the remote side.
273 rrdc_is_any_connected
275 Return a boolean int if any daemon connections are connected.
276 rrd_client_disconnect(rrd_client_t *client)
278 rrdc_disconnect
279 Disconnect gracefully from the present daemon connection.
280 rrd_client_update(rrd_client_t *client, const char *filename, int
282 values_num, const char * const *values)
283 rrdc_update(const char *filename, int values_num, const char * const
284 *values)
285 Update the RRD "filename" via the rrdcached. Where "values_num" is
286 the number of values to update and "values" are the new values to
287 add.
288 rrd_client_info(rrd_client_t *client, const char *filename)
290 rrdc_info(const char *filename)
291 Grab rrd info of the RRD "filename" from the connected cache
292 daemon. This function returns an rrd_info_t structure of the
293 following format:
294 typedef struct rrd_blob_t {
296 unsigned long size; /* size of the blob */
297 unsigned char *ptr; /* pointer */
298 } rrd_blob_t;
299 typedef enum rrd_info_type { RD_I_VAL = 0,
301 RD_I_CNT,
302 RD_I_STR,
303 RD_I_INT,
304 RD_I_BLO
305 } rrd_info_type_t;
306 typedef union rrd_infoval {
308 unsigned long u_cnt;
309 rrd_value_t u_val;
310 char *u_str;
311 int u_int;
312 rrd_blob_t u_blo;
313 } rrd_infoval_t;
314 typedef struct rrd_info_t {
316 char *key;
317 rrd_info_type_t type;
318 rrd_infoval_t value;
319 struct rrd_info_t *next;
320 } rrd_info_t;
321 rrd_client_last(rrd_client_t *client, const char *filename)
323 rrdc_last(const char *filename)
324 Grab the unix epoch of the last time RRD "filename" was updated.
325 rrd_client_first(rrd_client_t *client, const char *filename, int
327 rraindex)
328 rrdc_first(const char *filename, int rraindex)
329 Get the first value of the first sample of the RRD "filename", of
330 the "rraindex" RRA (Round Robin Archive) index number. The RRA
331 index number can be determined by pulling the rrd_info_t off the
332 RRD.
333 rrd_client_create(rrd_client_t *client, const char *filename, unsigned
335 long pdp_step, time_t last_up, int no_overwrite, int argc, const char
336 **argv)
337 rrdc_create(const char *filename, unsigned long pdp_step, time_t
338 last_up, int no_overwrite, int argc, const char **argv)
339 Create RRD database of path "filename". The RRD will have a step
340 size of "pfp_step", the unix epoch timestamp to start collecting
341 data from. The number of data sources and RRAs "argc" and the
342 definitions of the data sources and RRAs "argv". Lastly whether or
343 not to overwrite an existing RRD if one is found with the same
344 filename; "no_overwrite".
345 rrdc_create_r2(rrd_client_t *client, const char *filename, unsigned
347 long pdp_step, time_t last_up, int no_overwrite, const char **sources,
348 const char *template, int argc, const char **argv)
349 rrdc_create_r2(const char *filename, unsigned long pdp_step, time_t
350 last_up, int no_overwrite, const char **sources, const char *template,
351 int argc, const char **argv)
352 Create an RRD database in the daemon. rrdc_create_r2 has the same
353 parameters as rrdc_create with two added parameters of; "sources"
354 and "template".
355 where "template" is the file path to a RRD file template, with, the
357 form defined in rrdcreate(1),
358 The "sources" parameter defines series of file paths with data
360 defined, to prefill the RRD with. See rrdcreate(1) for more
361 details.
362 rrd_client_flush(rrd_client_t *client, const char *filename)
364 rrdc_flush(const char *filename)
365 flush the currently RRD cached in the daemon specified via
366 "filename".
367 rrd_client_forget(rrd_client_t *client, const char *filename)
369 rrdc_forget(const char *filename)
370 Drop the cached data for the RRD file specified via "filename".
371 rrdc_flush_if_daemon(const char *daemon_addr, const char *filename)
373 Flush the specified RRD given by "filename" only if the daemon
374 "daemon_addr" is up and connected.
375 rrd_client_fetch(rrd_client_t *client, const char *filename, const char
377 *cf, time_t *ret_start, time_t *ret_end, unsigned long *ret_step,
378 unsigned long *ret_ds_num, char ***ret_ds_names, rrd_value_t
379 **ret_data)
380 rrdc_fetch(const char *filename, const char *cf, time_t *ret_start,
381 time_t *ret_end, unsigned long *ret_step, unsigned long *ret_ds_num,
382 char ***ret_ds_names, rrd_value_t **ret_data)
383 Perform a fetch operation on the specified RRD Database given be
384 "filename", where "cf" is the consolidation function, "ret_start"
385 is the start time given by unix epoch, "ret_end" is the endtime.
386 "ret_step" is the step size in seconds, "ret_ds_num" the number of
387 data sources in the RRD, "ret_ds_names" the names of the data
388 sources, and a pointer to an rrd_value_t object to shlep the data.
389 rrdc_stats_get(rrd_client_t *client, rrdc_stats_t **ret_stats)
391 rrdc_stats_get(rrdc_stats_t **ret_stats)
392 Get stats from the connected daemon, via a linked list of the
393 following structure:
394 struct rrdc_stats_s {
396 const char *name;
397 uint16_t type;
398 #define RRDC_STATS_TYPE_GAUGE 0x0001
399 #define RRDC_STATS_TYPE_COUNTER 0x0002
400 uint16_t flags;
401 union {
402 uint64_t counter;
403 double gauge;
404 } value;
405 struct rrdc_stats_s *next;
406 };
407 typedef struct rrdc_stats_s rrdc_stats_t;
408 rrdc_stats_free(rrdc_stats_t *ret_stats)
410 Free the stats struct allocated via rrdc_stats_get.
411 SEE ALSO
413 rrcached(1) rrdfetch(1) rrdinfo(1) rrdlast(1) rrdcreate(1) rrdupdate(1)
414 rrdlast(1)
415
417 RRD Contributors <rrd-developers@lists.oetiker.ch>
4181.8.0 2022-03-14 librrd(3)