1 files changed, 69 insertions, 0 deletions
diff --git a/web/api/queries/incremental_sum/incremental_sum.c b/web/api/queries/incremental_sum/incremental_sum.c
new file mode 100644
index 000000000..131d85d78
--- /dev/null
+++ b/web/api/queries/incremental_sum/incremental_sum.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "incremental_sum.h"
+
+// ----------------------------------------------------------------------------
+// incremental sum
+
+struct grouping_incremental_sum {
+    calculated_number first;
+    calculated_number last;
+    size_t count;
+};
+
+void *grouping_create_incremental_sum(RRDR *r) {
+    (void)r;
+    return callocz(1, sizeof(struct grouping_incremental_sum));
+}
+
+// resets when switches dimensions
+// so, clear everything to restart
+void grouping_reset_incremental_sum(RRDR *r) {
+    struct grouping_incremental_sum *g = (struct grouping_incremental_sum *)r->internal.grouping_data;
+    g->first = 0;
+    g->last = 0;
+    g->count = 0;
+}
+
+void grouping_free_incremental_sum(RRDR *r) {
+    freez(r->internal.grouping_data);
+    r->internal.grouping_data = NULL;
+}
+
+void grouping_add_incremental_sum(RRDR *r, calculated_number value) {
+    if(!isnan(value)) {
+        struct grouping_incremental_sum *g = (struct grouping_incremental_sum *)r->internal.grouping_data;
+
+        if(unlikely(!g->count)) {
+            g->first = value;
+            g->count++;
+        }
+        else {
+            g->last = value;
+            g->count++;
+        }
+    }
+}
+
+calculated_number grouping_flush_incremental_sum(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) {
+    struct grouping_incremental_sum *g = (struct grouping_incremental_sum *)r->internal.grouping_data;
+
+    calculated_number value;
+
+    if(unlikely(!g->count)) {
+        value = 0.0;
+        *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY;
+    }
+    else if(unlikely(g->count == 1)) {
+        value = 0.0;
+    }
+    else {
+        value = g->last - g->first;
+    }
+
+    g->first = 0.0;
+    g->last = 0.0;
+    g->count = 0;
+
+    return value;
+}