core: add conditionals evaluation library. (#9749)

this is a library to evaluate conditionals
based on rules, rules are declared as matching elements
using record accessor.

Signed-off-by: Jorge Niedbalski <jnr@metaklass.org>

include/fluent-bit/flb_conditionals.h

@@ -0,0 +1,91 @@
+/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+
+/* Fluent Bit
+ * ==========
+ * Copyright (C) 2015-2024 The Fluent Bit Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef FLB_CONDITIONS_H
+#define FLB_CONDITIONS_H
+
+#include <fluent-bit/flb_info.h>
+#include <fluent-bit/flb_sds.h>
+#include <fluent-bit/flb_regex.h>
+#include <fluent-bit/flb_mp.h>
+#include <fluent-bit/flb_cfl_record_accessor.h>
+#include <monkey/mk_core.h>
+#include <fluent-bit/flb_mp_chunk.h>
+
+/* Context types enum */
+enum record_context_type {
+    RECORD_CONTEXT_BODY    = 0,
+    RECORD_CONTEXT_METADATA    = 1
+};
+
+struct flb_condition;
+
+enum flb_condition_operator {
+    FLB_COND_OP_AND,
+    FLB_COND_OP_OR
+};
+
+enum flb_rule_operator {
+    FLB_RULE_OP_EQ,
+    FLB_RULE_OP_NEQ,
+    FLB_RULE_OP_GT,
+    FLB_RULE_OP_LT,
+    FLB_RULE_OP_REGEX,
+    FLB_RULE_OP_IN,
+    FLB_RULE_OP_NOT_IN
+};
+
+struct flb_condition_rule {
+    struct flb_cfl_record_accessor *ra;  /* Record accessor for the field */
+    enum record_context_type context;    /* Whether rule applies to body or metadata */
+    enum flb_rule_operator op;
+    union {
+        flb_sds_t str_val;
+        double num_val;
+        struct {
+            flb_sds_t *values;
+            int count;
+        } array;
+    } value;
+    struct flb_regex *regex;
+    struct mk_list _head;
+};
+
+struct flb_condition {
+    enum flb_condition_operator op;
+    struct mk_list rules;
+};
+
+/* Core condition functions */
+struct flb_condition *flb_condition_create(enum flb_condition_operator op);
+
+int flb_condition_add_rule(struct flb_condition *cond,
+                          const char *field,
+                          enum flb_rule_operator op,
+                          void *value,
+                          int value_count,
+                          enum record_context_type context);
+
+void flb_condition_destroy(struct flb_condition *cond);
+
+/* Evaluation function */
+int flb_condition_evaluate(struct flb_condition *cond,
+                          struct flb_mp_chunk_record *record);
+
+#endif /* FLB_CONDITIONS_H */

src/CMakeLists.txt

@@ -88,6 +88,7 @@ set(src
   flb_lock.c
   flb_cfl_ra_key.c
   flb_cfl_record_accessor.c
+  flb_conditionals.c
   )
 
 # Config format