![[tokkee]](http://tokkee.org/images/avatar.png){kind=avatar}
diff --git a/src/core/memstore_expr.c b/src/core/memstore_expr.c
--- /dev/null
+++ b/src/core/memstore_expr.c
@@ -0,0 +1,464 @@
+/*
+ * SysDB - src/core/memstore_expr.c
+ * Copyright (C) 2014 Sebastian 'tokkee' Harl <sh@tokkee.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * This module implements arithmetic and logical expressions for in-memory
+ * stores.
+ */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif /* HAVE_CONFIG_H */
+
+#include "sysdb.h"
+#include "core/memstore-private.h"
+#include "core/data.h"
+#include "core/object.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * private data types
+ */
+
+/* iterate through either a list of child nodes or arrays */
+struct sdb_memstore_expr_iter {
+ sdb_memstore_obj_t *obj;
+ sdb_memstore_expr_t *expr;
+
+ sdb_avltree_iter_t *tree;
+
+ sdb_data_t array;
+ size_t array_idx;
+ bool free_array;
+
+ sdb_memstore_matcher_t *filter;
+};
+
+/*
+ * private types
+ */
+
+static int
+expr_init(sdb_object_t *obj, va_list ap)
+{
+ int type = va_arg(ap, int);
+ sdb_memstore_expr_t *left = va_arg(ap, sdb_memstore_expr_t *);
+ sdb_memstore_expr_t *right = va_arg(ap, sdb_memstore_expr_t *);
+ const sdb_data_t *value = va_arg(ap, const sdb_data_t *);
+
+ sdb_memstore_expr_t *expr = SDB_MEMSTORE_EXPR(obj);
+
+ if (type <= 0) {
+ if (! value)
+ return -1;
+ if ((type == TYPED_EXPR) && (! left))
+ return -1;
+ } else {
+ if (value)
+ return -1;
+ if ((! left) || (! right))
+ return -1;
+ }
+
+ if (value)
+ expr->data = *value;
+
+ sdb_object_ref(SDB_OBJ(left));
+ sdb_object_ref(SDB_OBJ(right));
+
+ expr->type = type;
+ expr->left = left;
+ expr->right = right;
+
+ /* unknown for now */
+ expr->data_type = -1;
+ return 0;
+} /* expr_init */
+
+static void
+expr_destroy(sdb_object_t *obj)
+{
+ sdb_memstore_expr_t *expr = SDB_MEMSTORE_EXPR(obj);
+ sdb_object_deref(SDB_OBJ(expr->left));
+ sdb_object_deref(SDB_OBJ(expr->right));
+
+ if (expr->data.type)
+ sdb_data_free_datum(&expr->data);
+} /* expr_destroy */
+
+static sdb_type_t expr_type = {
+ /* size = */ sizeof(sdb_memstore_expr_t),
+ /* init = */ expr_init,
+ /* destroy = */ expr_destroy,
+};
+
+/*
+ * public API
+ */
+
+sdb_memstore_expr_t *
+sdb_memstore_expr_create(int op, sdb_memstore_expr_t *left, sdb_memstore_expr_t *right)
+{
+ sdb_data_t value = SDB_DATA_INIT;
+ sdb_memstore_expr_t *e;
+
+ if ((op < 0) || (SDB_DATA_CONCAT < op) || (! left) || (! right))
+ return NULL;
+
+ if (left->type || right->type) {
+ e = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-expr", expr_type,
+ op, left, right, NULL));
+ e->data_type = sdb_data_expr_type(op, left->type, right->type);
+ return e;
+ }
+ /* else: both expressions are constant values; evaluate now */
+
+ if (sdb_data_expr_eval(op, &left->data, &right->data, &value))
+ return NULL;
+ e = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-constvalue", expr_type,
+ 0, NULL, NULL, &value));
+ e->data_type = value.type;
+ return e;
+} /* sdb_memstore_expr_create */
+
+sdb_memstore_expr_t *
+sdb_memstore_expr_typed(int typ, sdb_memstore_expr_t *expr)
+{
+ sdb_data_t value = { SDB_TYPE_INTEGER, { .integer = typ } };
+ sdb_memstore_expr_t *e;
+
+ if ((typ < SDB_HOST) || (SDB_ATTRIBUTE < typ))
+ return NULL;
+
+ e = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-typedexpr", expr_type,
+ TYPED_EXPR, expr, NULL, &value));
+ e->data_type = expr->data_type;
+ return e;
+} /* sdb_memstore_expr_typed */
+
+sdb_memstore_expr_t *
+sdb_memstore_expr_fieldvalue(int field)
+{
+ sdb_data_t value = { SDB_TYPE_INTEGER, { .integer = field } };
+ sdb_memstore_expr_t *e;
+
+ if ((field < SDB_FIELD_NAME) || (SDB_FIELD_TIMESERIES < field))
+ return NULL;
+ e = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-fieldvalue", expr_type,
+ FIELD_VALUE, NULL, NULL, &value));
+ e->data_type = SDB_FIELD_TYPE(field);
+ return e;
+} /* sdb_memstore_expr_fieldvalue */
+
+sdb_memstore_expr_t *
+sdb_memstore_expr_attrvalue(const char *name)
+{
+ sdb_data_t value = { SDB_TYPE_STRING, { .string = NULL} };
+ sdb_memstore_expr_t *expr;
+
+ value.data.string = strdup(name);
+ if (! value.data.string)
+ return NULL;
+
+ expr = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-attrvalue", expr_type,
+ ATTR_VALUE, NULL, NULL, &value));
+ if (! expr)
+ free(value.data.string);
+ expr->data_type = -1;
+ return expr;
+} /* sdb_memstore_expr_attrvalue */
+
+sdb_memstore_expr_t *
+sdb_memstore_expr_constvalue(const sdb_data_t *value)
+{
+ sdb_data_t data = SDB_DATA_INIT;
+ sdb_memstore_expr_t *e;
+
+ if (sdb_data_copy(&data, value))
+ return NULL;
+ e = SDB_MEMSTORE_EXPR(sdb_object_create("memstore-constvalue", expr_type,
+ 0, NULL, NULL, &data));
+ e->data_type = data.type;
+ return e;
+} /* sdb_memstore_expr_constvalue */
+
+int
+sdb_memstore_expr_eval(sdb_memstore_expr_t *expr, sdb_memstore_obj_t *obj,
+ sdb_data_t *res, sdb_memstore_matcher_t *filter)
+{
+ sdb_data_t v1 = SDB_DATA_INIT, v2 = SDB_DATA_INIT;
+ int status = 0;
+
+ if ((! expr) || (! res))
+ return -1;
+
+ if (filter && obj && (! sdb_memstore_matcher_matches(filter, obj, NULL)))
+ obj = NULL; /* this object does not exist */
+
+ if (! expr->type)
+ return sdb_data_copy(res, &expr->data);
+ else if (expr->type == FIELD_VALUE)
+ return sdb_memstore_get_field(obj, (int)expr->data.data.integer, res);
+ else if (expr->type == ATTR_VALUE) {
+ status = sdb_memstore_get_attr(obj, expr->data.data.string, res, filter);
+ if ((status < 0) && obj) {
+ /* attribute does not exist => NULL */
+ status = 0;
+ res->type = SDB_TYPE_STRING;
+ res->data.string = NULL;
+ }
+ return status;
+ }
+ else if (expr->type == TYPED_EXPR) {
+ int typ = (int)expr->data.data.integer;
+ if (typ != obj->type) {
+ /* we support self-references and { service, metric } -> host */
+ if ((typ != SDB_HOST)
+ || ((obj->type != SDB_SERVICE)
+ && (obj->type != SDB_METRIC)))
+ return -1;
+ obj = obj->parent;
+ }
+ return sdb_memstore_expr_eval(expr->left, obj, res, filter);
+ }
+
+ if (sdb_memstore_expr_eval(expr->left, obj, &v1, filter))
+ return -1;
+ if (sdb_memstore_expr_eval(expr->right, obj, &v2, filter)) {
+ sdb_data_free_datum(&v1);
+ return -1;
+ }
+
+ if (sdb_data_expr_eval(expr->type, &v1, &v2, res))
+ status = -1;
+ sdb_data_free_datum(&v1);
+ sdb_data_free_datum(&v2);
+ return status;
+} /* sdb_memstore_expr_eval */
+
+sdb_memstore_expr_iter_t *
+sdb_memstore_expr_iter(sdb_memstore_expr_t *expr, sdb_memstore_obj_t *obj,
+ sdb_memstore_matcher_t *filter)
+{
+ sdb_memstore_expr_iter_t *iter;
+ sdb_avltree_iter_t *tree = NULL;
+ sdb_data_t array = SDB_DATA_INIT;
+ bool free_array = 0;
+
+ if (! expr)
+ return NULL;
+
+ while (expr->type == TYPED_EXPR) {
+ int type = (int)expr->data.data.integer;
+
+ if (obj->type == type) {
+ /* self reference */
+ }
+ else if ((type == SDB_HOST)
+ && ((obj->type == SDB_SERVICE)
+ || (obj->type == SDB_METRIC))) {
+ /* reference to parent host */
+ obj = obj->parent;
+ }
+ else
+ break;
+ expr = expr->left;
+ }
+
+ if (expr->type == TYPED_EXPR) {
+ if (! obj)
+ return NULL;
+ if (obj->type == SDB_HOST) {
+ if (expr->data.data.integer == SDB_SERVICE)
+ tree = sdb_avltree_get_iter(HOST(obj)->services);
+ else if (expr->data.data.integer == SDB_METRIC)
+ tree = sdb_avltree_get_iter(HOST(obj)->metrics);
+ else if (expr->data.data.integer == SDB_ATTRIBUTE)
+ tree = sdb_avltree_get_iter(HOST(obj)->attributes);
+ }
+ else if (obj->type == SDB_SERVICE) {
+ if (expr->data.data.integer == SDB_ATTRIBUTE)
+ tree = sdb_avltree_get_iter(SVC(obj)->attributes);
+ }
+ else if (obj->type == SDB_METRIC) {
+ if (expr->data.data.integer == SDB_ATTRIBUTE)
+ tree = sdb_avltree_get_iter(METRIC(obj)->attributes);
+ }
+ }
+ else if (expr->type == FIELD_VALUE) {
+ if (! obj)
+ return NULL;
+ if (expr->data.data.integer == SDB_FIELD_BACKEND) {
+ /* while scanning the store, we hold a read lock, so it's safe to
+ * access the data without copying */
+ array.type = SDB_TYPE_ARRAY | SDB_TYPE_STRING;
+ array.data.array.length = obj->backends_num;
+ array.data.array.values = obj->backends;
+ }
+ }
+ else if (! expr->type) {
+ if (expr->data.type & SDB_TYPE_ARRAY)
+ array = expr->data;
+ }
+ else {
+ sdb_data_t value = SDB_DATA_INIT;
+ if (sdb_memstore_expr_eval(expr, obj, &value, filter))
+ return NULL;
+ if (! (value.type & SDB_TYPE_ARRAY)) {
+ sdb_data_free_datum(&value);
+ return NULL;
+ }
+ array = value;
+ free_array = 1;
+ }
+
+ if ((! tree) && (array.type == SDB_TYPE_NULL))
+ return NULL;
+
+ iter = calloc(1, sizeof(*iter));
+ if (! iter) {
+ if (free_array)
+ sdb_data_free_datum(&array);
+ return NULL;
+ }
+
+ sdb_object_ref(SDB_OBJ(obj));
+ sdb_object_ref(SDB_OBJ(expr));
+ sdb_object_ref(SDB_OBJ(filter));
+
+ iter->obj = obj;
+ iter->expr = expr;
+ iter->tree = tree;
+ iter->array = array;
+ iter->free_array = free_array;
+ iter->filter = filter;
+ return iter;
+} /* sdb_memstore_expr_iter */
+
+void
+sdb_memstore_expr_iter_destroy(sdb_memstore_expr_iter_t *iter)
+{
+ sdb_data_t null = SDB_DATA_INIT;
+
+ if (! iter)
+ return;
+
+ if (iter->tree)
+ sdb_avltree_iter_destroy(iter->tree);
+ iter->tree = NULL;
+
+ if (iter->free_array)
+ sdb_data_free_datum(&iter->array);
+ iter->array = null;
+ iter->array_idx = 0;
+
+ sdb_object_deref(SDB_OBJ(iter->obj));
+ sdb_object_deref(SDB_OBJ(iter->expr));
+ sdb_object_deref(SDB_OBJ(iter->filter));
+ free(iter);
+} /* sdb_memstore_expr_iter_destroy */
+
+bool
+sdb_memstore_expr_iter_has_next(sdb_memstore_expr_iter_t *iter)
+{
+ if (! iter)
+ return 0;
+
+ if (iter->tree) {
+ /* this function may be called before get_next,
+ * so we'll have to apply filters here as well */
+ if (iter->filter) {
+ sdb_memstore_obj_t *child;
+ while ((child = STORE_OBJ(sdb_avltree_iter_peek_next(iter->tree)))) {
+ if (sdb_memstore_matcher_matches(iter->filter, child, NULL))
+ break;
+ (void)sdb_avltree_iter_get_next(iter->tree);
+ }
+ }
+
+ return sdb_avltree_iter_has_next(iter->tree);
+ }
+
+ return iter->array_idx < iter->array.data.array.length;
+} /* sdb_memstore_expr_iter_has_next */
+
+sdb_data_t
+sdb_memstore_expr_iter_get_next(sdb_memstore_expr_iter_t *iter)
+{
+ sdb_data_t null = SDB_DATA_INIT;
+ sdb_data_t ret = SDB_DATA_INIT;
+ sdb_data_t tmp = SDB_DATA_INIT;
+
+ if (! iter)
+ return null;
+
+ if (iter->tree) {
+ sdb_memstore_obj_t *child;
+
+ while (42) {
+ child = STORE_OBJ(sdb_avltree_iter_get_next(iter->tree));
+ if (! child)
+ break;
+ if (iter->filter
+ && (! sdb_memstore_matcher_matches(iter->filter, child, NULL)))
+ continue;
+
+ if (sdb_memstore_expr_eval(iter->expr, child, &ret, iter->filter))
+ return null;
+ break;
+ }
+
+ /* Skip over any filtered objects */
+ if (iter->filter) {
+ while ((child = STORE_OBJ(sdb_avltree_iter_peek_next(iter->tree)))) {
+ if (sdb_memstore_matcher_matches(iter->filter, child, NULL))
+ break;
+ (void)sdb_avltree_iter_get_next(iter->tree);
+ }
+ }
+
+ return ret;
+ }
+
+ if (iter->array_idx >= iter->array.data.array.length)
+ return null;
+
+ ++iter->array_idx;
+ if (sdb_data_array_get(&iter->array, iter->array_idx - 1, &ret))
+ return null;
+ if (sdb_data_copy(&tmp, &ret))
+ return null;
+ ret = tmp;
+ return ret;
+} /* sdb_memstore_expr_iter_get_next */
+
+/* vim: set tw=78 sw=4 ts=4 noexpandtab : */
+