e5e011875e1775a1592c0511e06d5f3928121b50
1 /*
2 * SysDB - src/include/core/store.h
3 * Copyright (C) 2012 Sebastian 'tokkee' Harl <sh@tokkee.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
17 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
19 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
28 #ifndef SDB_CORE_STORE_H
29 #define SDB_CORE_STORE_H 1
31 #include "sysdb.h"
32 #include "core/object.h"
33 #include "core/data.h"
34 #include "core/time.h"
35 #include "core/timeseries.h"
36 #include "parser/ast.h"
37 #include "utils/strbuf.h"
39 #include <stdbool.h>
40 #include <stdio.h>
42 #ifdef __cplusplus
43 extern "C" {
44 #endif
46 /*
47 * Store object types.
48 */
49 enum {
50 SDB_HOST = 1,
51 SDB_SERVICE,
52 SDB_METRIC,
54 SDB_ATTRIBUTE = 1 << 4,
56 /*
57 * Queryable fields of a stored object.
58 */
59 SDB_FIELD_NAME = 1 << 8, /* type: string */
60 SDB_FIELD_LAST_UPDATE, /* type: datetime */
61 SDB_FIELD_AGE, /* type: datetime */
62 SDB_FIELD_INTERVAL, /* type: datetime */
63 SDB_FIELD_BACKEND, /* type: array of strings */
64 SDB_FIELD_VALUE, /* attributes only; type: type of the value */
65 SDB_FIELD_TIMESERIES, /* metrics only; type: boolean */
66 };
67 #define SDB_STORE_TYPE_TO_NAME(t) \
68 (((t) == SDB_HOST) ? "host" \
69 : ((t) == SDB_SERVICE) ? "service" \
70 : ((t) == SDB_METRIC) ? "metric" \
71 : ((t) == SDB_ATTRIBUTE) ? "attribute" \
72 : ((t) == (SDB_ATTRIBUTE | SDB_HOST)) ? "host attribute" \
73 : ((t) == (SDB_ATTRIBUTE | SDB_SERVICE)) ? "service attribute" \
74 : ((t) == (SDB_ATTRIBUTE | SDB_METRIC)) ? "metric attribute" \
75 : "unknown")
77 #define SDB_FIELD_TO_NAME(f) \
78 (((f) == SDB_FIELD_NAME) ? "name" \
79 : ((f) == SDB_FIELD_LAST_UPDATE) ? "last-update" \
80 : ((f) == SDB_FIELD_AGE) ? "age" \
81 : ((f) == SDB_FIELD_INTERVAL) ? "interval" \
82 : ((f) == SDB_FIELD_BACKEND) ? "backend" \
83 : ((f) == SDB_FIELD_VALUE) ? "value" \
84 : ((f) == SDB_FIELD_TIMESERIES) ? "timeseries" \
85 : "unknown")
87 #define SDB_FIELD_TYPE(f) \
88 (((f) == SDB_FIELD_NAME) ? SDB_TYPE_STRING \
89 : ((f) == SDB_FIELD_LAST_UPDATE) ? SDB_TYPE_DATETIME \
90 : ((f) == SDB_FIELD_AGE) ? SDB_TYPE_DATETIME \
91 : ((f) == SDB_FIELD_INTERVAL) ? SDB_TYPE_DATETIME \
92 : ((f) == SDB_FIELD_BACKEND) ? (SDB_TYPE_ARRAY | SDB_TYPE_STRING) \
93 : ((f) == SDB_FIELD_VALUE) ? -1 /* unknown */ \
94 : ((f) == SDB_FIELD_TIMESERIES) ? SDB_TYPE_BOOLEAN \
95 : -1)
97 /*
98 * sdb_store_t represents an in-memory store. It inherits from sdb_object_t
99 * and may safely be case to a generic object.
100 */
101 struct sdb_store;
102 typedef struct sdb_store sdb_store_t;
103 #define SDB_STORE(obj) ((sdb_store_t *)(obj))
105 /*
106 * sdb_store_obj_t represents the super-class of any object stored in the
107 * database. It inherits from sdb_object_t and may safely be cast to a generic
108 * object to access its name.
109 */
110 struct sdb_store_obj;
111 typedef struct sdb_store_obj sdb_store_obj_t;
113 /*
114 * A metric store describes how to access a metric's data.
115 */
116 typedef struct {
117 const char *type;
118 const char *id;
119 } sdb_metric_store_t;
121 /*
122 * Expressions represent arithmetic expressions based on stored objects and
123 * their various attributes.
124 *
125 * An expression object inherits from sdb_object_t and, thus, may safely be
126 * cast to a generic object.
127 */
128 struct sdb_store_expr;
129 typedef struct sdb_store_expr sdb_store_expr_t;
130 #define SDB_STORE_EXPR(obj) ((sdb_store_expr_t *)(obj))
132 /*
133 * An expression iterator iterates over the values of an iterable expression
134 * (see sdb_store_expr_iterable).
135 */
136 struct sdb_store_expr_iter;
137 typedef struct sdb_store_expr_iter sdb_store_expr_iter_t;
139 /*
140 * Store matchers may be used to lookup hosts from the store based on their
141 * various attributes. Service and attribute matchers are applied to a host's
142 * services and attributes and evaluate to true if *any* service or attribute
143 * matches.
144 *
145 * A store matcher object inherits from sdb_object_t and, thus, may safely be
146 * cast to a generic object.
147 */
148 struct sdb_store_matcher;
149 typedef struct sdb_store_matcher sdb_store_matcher_t;
150 #define SDB_STORE_MATCHER(obj) ((sdb_store_matcher_t *)(obj))
152 /*
153 * A JSON formatter converts stored objects into the JSON format.
154 * See http://www.ietf.org/rfc/rfc4627.txt
155 *
156 * A JSON formatter object inherits from sdb_object_t and, thus, may safely be
157 * cast to a generic object.
158 */
159 struct sdb_store_json_formatter;
160 typedef struct sdb_store_json_formatter sdb_store_json_formatter_t;
162 /*
163 * A store writer describes the interface for plugins implementing a store.
164 *
165 * Any of the call-back functions shall return:
166 * - 0 on success
167 * - a positive value if the new entry is older than the currently stored
168 * entry (in this case, no update will happen)
169 * - a negative value on error
170 */
171 typedef struct {
172 /*
173 * store_host:
174 * Add/update a host in the store. If the host, identified by its
175 * canonicalized name, already exists, it will be updated according to the
176 * specified name and timestamp. Else, a new entry will be created in the
177 * store.
178 */
179 int (*store_host)(const char *name, sdb_time_t last_update,
180 sdb_object_t *user_data);
182 /*
183 * store_service:
184 * Add/update a service in the store. If the service, identified by its
185 * name, already exists for the specified host, it will be updated
186 * according to the specified name and timestamp. If the referenced host
187 * does not exist, an error will be reported. Else, a new entry will be
188 * created in the store.
189 */
190 int (*store_service)(const char *hostname, const char *name,
191 sdb_time_t last_update, sdb_object_t *user_data);
193 /*
194 * store_metric:
195 * Add/update a metric in the store. If the metric, identified by its
196 * name, already exists for the specified host, it will be updated
197 * according to the specified attributes. If the referenced host does not
198 * exist, an error will be reported. Else, a new entry will be created in
199 * the store.
200 */
201 int (*store_metric)(const char *hostname, const char *name,
202 sdb_metric_store_t *store, sdb_time_t last_update,
203 sdb_object_t *user_data);
205 /*
206 * store_attribute:
207 * Add/update a host's attribute in the store. If the attribute,
208 * identified by its key, already exists for the specified host, it will
209 * be updated to the specified values. If the referenced host does not
210 * exist, an error will be reported. Else, a new entry will be created in
211 * the store.
212 */
213 int (*store_attribute)(const char *hostname,
214 const char *key, const sdb_data_t *value, sdb_time_t last_update,
215 sdb_object_t *user_data);
217 /*
218 * store_service_attr:
219 * Add/update a service's attribute in the store. If the attribute,
220 * identified by its key, already exists for the specified service, it
221 * will be updated to the specified value. If the references service (for
222 * the specified host) does not exist, an error will be reported.
223 */
224 int (*store_service_attr)(const char *hostname, const char *service,
225 const char *key, const sdb_data_t *value, sdb_time_t last_update,
226 sdb_object_t *user_data);
228 /*
229 * store_metric_attr:
230 * Add/update a metric's attribute in the store. If the attribute,
231 * identified by its key, already exists for the specified metric, it will
232 * be updated to the specified value. If the references metric (for the
233 * specified host) does not exist, an error will be reported.
234 */
235 int (*store_metric_attr)(const char *hostname, const char *metric,
236 const char *key, const sdb_data_t *value, sdb_time_t last_update,
237 sdb_object_t *user_data);
238 } sdb_store_writer_t;
240 /*
241 * sdb_store_writer:
242 * A store writer implementation that provides an in-memory object store. It
243 * expects a store object as its user-data argument.
244 */
245 extern sdb_store_writer_t sdb_store_writer;
247 /*
248 * A store reader describes the interface to query a store implementation.
249 */
250 typedef struct {
251 /*
252 * prepare_query:
253 * Prepare the query described by 'ast' for execution.
254 */
255 sdb_object_t *(*prepare_query)(sdb_ast_node_t *ast,
256 sdb_strbuf_t *errbuf, sdb_object_t *user_data);
258 /*
259 * execute_query:
260 * Execute a previously prepared query. The callback may expect that only
261 * queries prepared by its respective prepare callback will be passed to
262 * this function.
263 *
264 * TODO: Instead of letting the executor write directly to a string buffer
265 * (which cannot easily be merged with other results), let it hand
266 * all objects to a store-writer.
267 */
268 int (*execute_query)(sdb_object_t *q,
269 sdb_strbuf_t *buf, sdb_strbuf_t *errbuf,
270 sdb_object_t *user_data);
271 } sdb_store_reader_t;
273 /*
274 * sdb_store_reader:
275 * A store reader implementation that uses an in-memory object store. It
276 * expects a store object as its user-data argument.
277 */
278 extern sdb_store_reader_t sdb_store_reader;
280 /*
281 * sdb_store_create:
282 * Allocate a new in-memory store.
283 */
284 sdb_store_t *
285 sdb_store_create(void);
287 /*
288 * sdb_store_init:
289 * Initialize the store sub-system. This function has to be called before
290 * doing any other store operations.
291 *
292 * Returns:
293 * - 0 on success
294 * - a negative value else
295 */
296 int
297 sdb_store_init(void);
299 /*
300 * sdb_store_clear:
301 * Clear the entire store and remove all stored objects.
302 */
303 void
304 sdb_store_clear(void);
306 /*
307 * sdb_store_get_host:
308 * Query the store for a host by its (canonicalized) name.
309 *
310 * The function increments the ref count of the host object. The caller needs
311 * to deref it when no longer using it.
312 */
313 sdb_store_obj_t *
314 sdb_store_get_host(const char *name);
316 /*
317 * sdb_store_fetch_timeseries:
318 * Fetch the time-series described by the specified host's metric and
319 * serialize it as JSON into the provided string buffer.
320 *
321 * Returns:
322 * - 0 on success
323 * - a negative value else
324 */
325 int
326 sdb_store_fetch_timeseries(const char *hostname, const char *metric,
327 sdb_timeseries_opts_t *opts, sdb_strbuf_t *buf);
329 /*
330 * sdb_store_get_child:
331 * Retrieve a host's child object of the specified type and name. The
332 * reference count of the child object will be incremented before returning
333 * it. The caller is responsible for releasing the object once it's no longer
334 * used.
335 *
336 * Returns:
337 * - the child object on success
338 * - NULL else
339 */
340 sdb_store_obj_t *
341 sdb_store_get_child(sdb_store_obj_t *host, int type, const char *name);
343 /*
344 * sdb_store_get_field:
345 * Get the value of a stored object's queryable field. The caller is
346 * responsible for freeing any dynamically allocated memory possibly stored in
347 * the returned value. If 'res' is NULL, the function will return whether the
348 * field exists.
349 *
350 * Returns:
351 * - 0 on success
352 * - a negative value else
353 */
354 int
355 sdb_store_get_field(sdb_store_obj_t *obj, int field, sdb_data_t *res);
357 /*
358 * sdb_store_get_attr:
359 * Get the value of a stored object's attribute. The caller is responsible for
360 * freeing any dynamically allocated memory possibly stored in the returned
361 * value. If 'res' is NULL, the function will return whether the attribute
362 * exists. If specified, only attributes matching the filter will be
363 * considered.
364 *
365 * Returns:
366 * - 0 if the attribute exists
367 * - a negative value else
368 */
369 int
370 sdb_store_get_attr(sdb_store_obj_t *obj, const char *name, sdb_data_t *res,
371 sdb_store_matcher_t *filter);
373 /*
374 * Querying a store:
375 *
376 * - Query interface: A query is a formal description of an interaction with
377 * the store. It can be used, both, for read and write access. The query is
378 * described by its abstract syntax tree (AST). The parser package provides
379 * means to parse a string (SysQL) representation of the query into an AST.
380 *
381 * - Matcher / expression interface: This low-level interface provides direct
382 * control over how to access the store. It is used by the query
383 * implementation internally and can only be used for read access.
384 */
386 /*
387 * sdb_store_query_t:
388 * A parsed query readily prepared for execution.
389 */
390 struct sdb_store_query;
391 typedef struct sdb_store_query sdb_store_query_t;
393 /*
394 * sdb_store_query_prepare:
395 * Prepare the query described by 'ast' for execution in a store.
396 *
397 * Returns:
398 * - a store query on success
399 * - NULL else
400 */
401 sdb_store_query_t *
402 sdb_store_query_prepare(sdb_ast_node_t *ast);
404 /*
405 * sdb_store_query_prepare_matcher:
406 * Prepare the logical expression described by 'ast' for execution as a store
407 * matcher.
408 *
409 * Returns:
410 * - a matcher on success
411 * - NULL else
412 */
413 sdb_store_matcher_t *
414 sdb_store_query_prepare_matcher(sdb_ast_node_t *ast);
416 /*
417 * sdb_store_query_execute:
418 * Execute a previously prepared query. The query result will be written to
419 * 'buf' and any errors to 'errbuf'.
420 *
421 * Returns:
422 * - the result type (to be used by the server reply)
423 * - a negative value on error
424 */
425 int
426 sdb_store_query_execute(sdb_store_query_t *m,
427 sdb_strbuf_t *buf, sdb_strbuf_t *errbuf);
429 /*
430 * sdb_store_expr_create:
431 * Creates an arithmetic expression implementing the specified operator on the
432 * specified left and right operand.
433 *
434 * Returns:
435 * - an expression object on success
436 * - NULL else
437 */
438 sdb_store_expr_t *
439 sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right);
441 /*
442 * sdb_store_expr_typed:
443 * Creates an expression which evaluates in the context of an object's sibling
444 * as specified by the given type.
445 *
446 * Returns:
447 * - an expression object on success
448 * - NULL else
449 */
450 sdb_store_expr_t *
451 sdb_store_expr_typed(int typ, sdb_store_expr_t *expr);
453 /*
454 * sdb_store_expr_fieldvalue:
455 * Creates an expression which evaluates to the value of the specified
456 * queryable field of a stored object.
457 *
458 * Returns:
459 * - an expression object on success
460 * - NULL else
461 */
462 sdb_store_expr_t *
463 sdb_store_expr_fieldvalue(int field);
465 /*
466 * sdb_store_expr_attrvalue:
467 * Creates an expression which evaluates to the value of the specified
468 * attribute of a stored object. Evaluates to a NULL value if the attribute
469 * does not exist.
470 *
471 * Returns:
472 * - an expression object on success
473 * - NULL else
474 */
475 sdb_store_expr_t *
476 sdb_store_expr_attrvalue(const char *name);
478 /*
479 * sdb_store_expr_constvalue:
480 * Creates an expression which evaluates to the specified constant value.
481 *
482 * Returns:
483 * - an expression object on success
484 * - NULL else
485 */
486 sdb_store_expr_t *
487 sdb_store_expr_constvalue(const sdb_data_t *value);
489 /*
490 * sdb_store_expr_eval:
491 * Evaluate an expression for the specified stored object and stores the
492 * result in 'res'. The result's value will be allocated dynamically if
493 * necessary and, thus, should be free'd by the caller (e.g. using
494 * sdb_data_free_datum). The object may be NULL, in which case the expression
495 * needs to evaluate to a constant value. If specified, only objects matching
496 * the filter will be used during the evaluation.
497 *
498 * Returns:
499 * - 0 on success
500 * - a negative value else
501 */
502 int
503 sdb_store_expr_eval(sdb_store_expr_t *expr, sdb_store_obj_t *obj,
504 sdb_data_t *res, sdb_store_matcher_t *filter);
506 /*
507 * sdb_store_expr_iterable:
508 * Check whether an expression, evaluated in the specified context (HOST,
509 * SERVICE, METRIC) is iterable, that is, if it may evaluate to multiple
510 * values.
511 */
512 bool
513 sdb_store_expr_iterable(sdb_store_expr_t *expr, int context);
515 /*
516 * sdb_store_expr_iter:
517 * Iterate over the elements of an iterable expression. sdb_store_expr_iter
518 * returns NULL if the expression is not iterable (for the specified object).
519 * See also sdb_store_expr_iterable.
520 *
521 * sdb_store_expr_iter_get_next returns NULL if there is no next element.
522 */
523 sdb_store_expr_iter_t *
524 sdb_store_expr_iter(sdb_store_expr_t *expr, sdb_store_obj_t *obj,
525 sdb_store_matcher_t *filter);
526 void
527 sdb_store_expr_iter_destroy(sdb_store_expr_iter_t *iter);
529 bool
530 sdb_store_expr_iter_has_next(sdb_store_expr_iter_t *iter);
531 sdb_data_t
532 sdb_store_expr_iter_get_next(sdb_store_expr_iter_t *iter);
534 /*
535 * sdb_store_dis_matcher:
536 * Creates a matcher matching the disjunction (logical OR) of two matchers.
537 */
538 sdb_store_matcher_t *
539 sdb_store_dis_matcher(sdb_store_matcher_t *left, sdb_store_matcher_t *right);
541 /*
542 * sdb_store_con_matcher:
543 * Creates a matcher matching the conjunction (logical AND) of two matchers.
544 */
545 sdb_store_matcher_t *
546 sdb_store_con_matcher(sdb_store_matcher_t *left, sdb_store_matcher_t *right);
548 /*
549 * sdb_store_inv_matcher::
550 * Creates a matcher matching the inverse (logical NOT) of a matcher.
551 */
552 sdb_store_matcher_t *
553 sdb_store_inv_matcher(sdb_store_matcher_t *m);
555 /*
556 * sdb_store_any_matcher:
557 * Creates a matcher iterating over values of the first expression (which has
558 * to be iterable). It matches if *any* of those elements match 'm'. 'm' has
559 * to be an ary operation with the left operand unset.
560 */
561 sdb_store_matcher_t *
562 sdb_store_any_matcher(sdb_store_expr_t *iter, sdb_store_matcher_t *m);
564 /*
565 * sdb_store_all_matcher:
566 * Creates a matcher iterating over values of the first expression (which has
567 * to be iterable). It matches if *all* of those elements match 'm'. 'm' has
568 * to be an ary operation with the left operand unset.
569 */
570 sdb_store_matcher_t *
571 sdb_store_all_matcher(sdb_store_expr_t *iter, sdb_store_matcher_t *m);
573 /*
574 * sdb_store_in_matcher:
575 * Creates a matcher which matches if the right value evaluates to an array
576 * value and the left value is included in that array. See sdb_data_inarray
577 * for more details.
578 */
579 sdb_store_matcher_t *
580 sdb_store_in_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
582 /*
583 * sdb_store_lt_matcher, sdb_store_le_matcher, sdb_store_eq_matcher,
584 * sdb_store_ge_matcher, sdb_store_gt_matcher:
585 * Create conditional matchers comparing the values of two expressions. The
586 * matcher matches if the left expression compres less than, less or equal
587 * than, equal to, not equal to, greater or equal than, or greater than the
588 * right expression.
589 */
590 sdb_store_matcher_t *
591 sdb_store_lt_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
592 sdb_store_matcher_t *
593 sdb_store_le_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
594 sdb_store_matcher_t *
595 sdb_store_eq_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
596 sdb_store_matcher_t *
597 sdb_store_ne_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
598 sdb_store_matcher_t *
599 sdb_store_ge_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
600 sdb_store_matcher_t *
601 sdb_store_gt_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
603 /*
604 * sdb_store_regex_matcher:
605 * Creates a matcher which matches the string value the left expression
606 * evaluates to against the regular expression the right expression evaluates
607 * to. The right expression may either be a constant value regular expression
608 * or string or a dynamic value evaluating to a string. In the latter case,
609 * the string is compiled to a regex every time the matcher is executed.
610 */
611 sdb_store_matcher_t *
612 sdb_store_regex_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
614 /*
615 * sdb_store_nregex_matcher:
616 * Creates a regex matcher just like sdb_store_regex_matcher except that it
617 * matches in case the regular expression does not match.
618 */
619 sdb_store_matcher_t *
620 sdb_store_nregex_matcher(sdb_store_expr_t *left, sdb_store_expr_t *right);
622 /*
623 * sdb_store_isnull_matcher:
624 * Creates a matcher matching NULL values.
625 */
626 sdb_store_matcher_t *
627 sdb_store_isnull_matcher(sdb_store_expr_t *expr);
629 /*
630 * sdb_store_istrue_matcher, sdb_store_isfalse_matcher:
631 * Creates a matcher matching boolean values.
632 */
633 sdb_store_matcher_t *
634 sdb_store_istrue_matcher(sdb_store_expr_t *expr);
635 sdb_store_matcher_t *
636 sdb_store_isfalse_matcher(sdb_store_expr_t *expr);
638 /*
639 * sdb_store_matcher_matches:
640 * Check whether the specified matcher matches the specified store object. If
641 * specified, the filter will be used to preselect objects for further
642 * evaluation. It is applied to any object that's used during the evaluation
643 * of the matcher. Only those objects matching the filter will be considered.
644 *
645 * Note that the filter is applied to all object types (hosts, service,
646 * metric, attribute). Thus, any object-specific matchers are mostly unsuited
647 * for this purpose and, if used, may result in unexpected behavior.
648 *
649 * Returns:
650 * - 1 if the object matches
651 * - 0 else
652 */
653 int
654 sdb_store_matcher_matches(sdb_store_matcher_t *m, sdb_store_obj_t *obj,
655 sdb_store_matcher_t *filter);
657 /*
658 * sdb_store_matcher_op_cb:
659 * Callback constructing a matcher operator.
660 */
661 typedef sdb_store_matcher_t *(*sdb_store_matcher_op_cb)
662 (sdb_store_expr_t *, sdb_store_expr_t *);
664 /*
665 * sdb_store_lookup_cb:
666 * Lookup callback. It is called for each matching object when looking up data
667 * in the store passing on the lookup filter and the specified user-data. The
668 * lookup aborts early if the callback returns non-zero.
669 */
670 typedef int (*sdb_store_lookup_cb)(sdb_store_obj_t *obj,
671 sdb_store_matcher_t *filter, void *user_data);
673 /*
674 * sdb_store_scan:
675 * Look up objects of the specified type in the store. The specified callback
676 * function is called for each object in the store matching 'm'. The function
677 * performs a full scan of all objects stored in the database. If specified,
678 * the filter will be used to preselect objects for further evaluation. See
679 * the description of 'sdb_store_matcher_matches' for details.
680 *
681 * Returns:
682 * - 0 on success
683 * - a negative value else
684 */
685 int
686 sdb_store_scan(int type, sdb_store_matcher_t *m, sdb_store_matcher_t *filter,
687 sdb_store_lookup_cb cb, void *user_data);
689 /*
690 * Flags for JSON formatting.
691 */
692 enum {
693 SDB_WANT_ARRAY = 1 << 0,
694 };
696 /*
697 * sdb_store_json_formatter:
698 * Create a JSON formatter for the specified object types writing to the
699 * specified buffer.
700 */
701 sdb_store_json_formatter_t *
702 sdb_store_json_formatter(sdb_strbuf_t *buf, int type, int flags);
704 /*
705 * sdb_store_json_emit:
706 * Serialize a single object to JSON adding it to the string buffer associated
707 * with the formatter object. The serialized object will not include
708 * attributes or any child objects. Instead, call the function again for each
709 * of those objects. All attributes have to be emitted before any other
710 * children types. Use sdb_store_json_emit_full() to emit a full (filtered)
711 * object.
712 *
713 * Note that the output might not be valid JSON before calling
714 * sdb_store_json_finish().
715 *
716 * Returns:
717 * - 0 on success
718 * - a negative value else
719 */
720 int
721 sdb_store_json_emit(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj);
723 /*
724 * sdb_store_json_emit_full:
725 * Serialize a single object including it's attributes and all children to
726 * JSON, adding it to the string buffer associated with the formatter object.
727 * The filter, if specified, is applied to each attribute and child object.
728 * Only matching objects will be included in the output.
729 *
730 * Note that the output might not be valid JSON before calling
731 * sdb_store_json_finish().
732 *
733 * Returns:
734 * - 0 on success
735 * - a negative value else
736 */
737 int
738 sdb_store_json_emit_full(sdb_store_json_formatter_t *f, sdb_store_obj_t *obj,
739 sdb_store_matcher_t *filter);
741 /*
742 * sdb_store_json_finish:
743 * Finish the JSON output. This function has to be called once after emiting
744 * all objects.
745 */
746 int
747 sdb_store_json_finish(sdb_store_json_formatter_t *f);
749 #ifdef __cplusplus
750 } /* extern "C" */
751 #endif
753 #endif /* ! SDB_CORE_STORE_H */
755 /* vim: set tw=78 sw=4 ts=4 noexpandtab : */