store, frontend: Let lookups support arbitrary expressions for comparison.

[sysdb.git] / src / include / core / store.h

diff --git a/src/include/core/store.h b/src/include/core/store.h
index 1d64c4b7bee0a0f2d3944272521f3c74a85bc472..574b01ed262adcfd88d2a6be63afdff7285300a9 100644 (file)
--- a/src/include/core/store.h
+++ b/src/include/core/store.h
@@ -32,7 +32,6 @@
 #include "core/object.h"
 #include "core/data.h"
 #include "core/time.h"
-#include "utils/llist.h"
 #include "utils/strbuf.h"
 
 #include <stdio.h>
@@ -159,6 +158,52 @@ int
 sdb_store_service_attr(const char *hostname, const char *service,
                const char *key, const sdb_data_t *value, sdb_time_t last_update);
 
+/*
+ * Expressions specify arithmetic expressions.
+ *
+ * A expression object inherits from sdb_object_t and, thus, may safely be
+ * cast to a generic object.
+ */
+struct sdb_store_expr;
+typedef struct sdb_store_expr sdb_store_expr_t;
+#define SDB_STORE_EXPR(obj) ((sdb_store_expr_t *)(obj))
+
+/*
+ * sdb_store_expr_create:
+ * Creates an arithmetic expression implementing the specified operator on the
+ * specified left and right operand.
+ *
+ * Returns:
+ *  - an expression object on success
+ *  - NULL else
+ */
+sdb_store_expr_t *
+sdb_store_expr_create(int op, sdb_store_expr_t *left, sdb_store_expr_t *right);
+
+/*
+ * sdb_store_expr_constvalue:
+ * Creates an expression which evaluates to the specified constant value.
+ *
+ * Returns:
+ *  - an expression object on success
+ *  - NULL else
+ */
+sdb_store_expr_t *
+sdb_store_expr_constvalue(const sdb_data_t *value);
+
+/*
+ * sdb_store_expr_eval:
+ * Evaluate an expression and stores the result in 'res'. The result's value
+ * will be allocated dynamically if necessary and, thus, should be free'd by
+ * the caller (e.g. using sdb_data_free_datum);
+ *
+ * Returns:
+ *  - 0 on success
+ *  - a negative value else
+ */
+int
+sdb_store_expr_eval(sdb_store_expr_t *expr, sdb_data_t *res);
+
 /*
  * Conditionals may be used to lookup hosts from the store based on a
  * conditional expression.
@@ -173,11 +218,11 @@ typedef struct sdb_store_cond sdb_store_cond_t;
 /*
  * sdb_store_attr_cond:
  * Creates a conditional based on attribute values. The value of stored
- * attributes is compared against the specified value. See sdb_data_cmp for
- * details about the comparison.
+ * attributes is compared against the value the expression evaluates to. See
+ * sdb_data_cmp for details about the comparison.
  */
 sdb_store_cond_t *
-sdb_store_attr_cond(const char *name, const sdb_data_t *value);
+sdb_store_attr_cond(const char *name, sdb_store_expr_t *expr);
 
 /*
  * Store matchers may be used to lookup hosts from the store based on their
@@ -210,6 +255,13 @@ sdb_store_name_matcher(int type, const char *name, _Bool re);
 sdb_store_matcher_t *
 sdb_store_attr_matcher(const char *name, const char *value, _Bool re);
 
+/*
+ * sdb_store_isnull_matcher:
+ * Creates a matcher matching "missing" attributes.
+ */
+sdb_store_matcher_t *
+sdb_store_isnull_matcher(const char *attr_name);
+
 /*
  * sdb_store_lt_matcher, sdb_store_le_matcher, sdb_store_eq_matcher,
  * sdb_store_ge_matcher, sdb_store_gt_matcher:
@@ -231,7 +283,7 @@ sdb_store_gt_matcher(sdb_store_cond_t *cond);
 
 /*
  * sdb_store_matcher_parse_cmp:
- * Parse a simple compare expression (<obj_type>.<attr> <op> <value>).
+ * Parse a simple compare expression (<obj_type>.<attr> <op> <expression>).
  *
  * Returns:
  *  - a matcher object on success
@@ -239,7 +291,7 @@ sdb_store_gt_matcher(sdb_store_cond_t *cond);
  */
 sdb_store_matcher_t *
 sdb_store_matcher_parse_cmp(const char *obj_type, const char *attr,
-               const char *op, const sdb_data_t *value);
+               const char *op, sdb_store_expr_t *expr);
 
 /*
  * sdb_store_dis_matcher:
@@ -289,16 +341,17 @@ sdb_store_matcher_tostring(sdb_store_matcher_t *m, char *buf, size_t buflen);
 typedef int (*sdb_store_lookup_cb)(sdb_store_obj_t *obj, void *user_data);
 
 /*
- * sdb_store_lookup:
+ * sdb_store_scan:
  * Look up objects in the store. The specified callback function is called for
- * each object in the store matching 'm'.
+ * each object in the store matching 'm'. The function performs a full scan of
+ * all hosts stored in the database.
  *
  * Returns:
  *  - 0 on success
  *  - a negative value else
  */
 int
-sdb_store_lookup(sdb_store_matcher_t *m, sdb_store_lookup_cb cb,
+sdb_store_scan(sdb_store_matcher_t *m, sdb_store_lookup_cb cb,
                void *user_data);
 
 /*