From f7d6d8fe1f56cc1d0d45c5cfcb6ccdff915b4f21 Mon Sep 17 00:00:00 2001
From: Hugo Osvaldo Barrera <hugo@whynothugo.nl>
Date: Tue, 12 May 2026 19:00:23 +0200
Subject: [PATCH] Avoid walking all entries to find latest

Finding the latest entry walks though the whole directory tree seeking
the exact matching entry. However, the filename of the entry that should
match is predictable.

Instead of walking through all entries to find the latest matching one,
open the exact expected file.

References: https://github.com/owntracks/recorder/issues/565
---
 recorder.c | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/recorder.c b/recorder.c
index 7e38249..c582c31 100644
--- a/recorder.c
+++ b/recorder.c
@@ -709,26 +709,27 @@ unsigned char *decrypt(struct udata *ud, char *topic, char *p64, char *username,
 static bool is_newer_than_last(JsonNode *json)
 {
 	bool is_newer = true;
-	JsonNode *last_array;
-	JsonNode *fields = json_mkarray();
-	json_append_element(fields, json_mkstring("tst"));
 	JsonNode *usernode = json_find_member(json, "username");
 	JsonNode *devicenode = json_find_member(json, "device");
-	if (usernode != NULL && devicenode != NULL) {
-		if ((last_array = last_users(usernode->string_, devicenode->string_, fields)) != NULL) {
-			JsonNode *lastrec = json_first_child(last_array);
-			if (lastrec != NULL) {
-				JsonNode *tst = json_find_member(lastrec, "tst");
-				if (tst != NULL) {
-					double last = number(lastrec, "tst");
-					double current = number(json, "tst");
-					is_newer = last < current;
-				}
-			}
-			json_delete(last_array);
+
+	if (usernode != NULL && devicenode != NULL &&
+	    usernode->tag == JSON_STRING && devicenode->tag == JSON_STRING) {
+		JsonNode *last_json = json_mkobject();
+		char path[BUFSIZ * 2];
+
+		snprintf(path, sizeof(path), "%s/last/%s/%s/%s-%s.json",
+			STORAGEDIR, usernode->string_, devicenode->string_,
+			usernode->string_, devicenode->string_);
+
+		if (json_copy_from_file(last_json, path) == TRUE) {
+			double last = number(last_json, "tst");
+			double current = number(json, "tst");
+
+			if (!isnan(last) && !isnan(current))
+				is_newer = last < current;
 		}
+		json_delete(last_json);
 	}
-	json_delete(fields);
 	return is_newer;
 }