From 83bc362dacfdef2bdf18cae5e2c52f526e8431c5 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Sun, 26 May 2024 14:28:30 +0200
Subject: [PATCH] Mark Redis database backend as deprecated (#14679)

---
 src/database/database-redis.cpp | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/database/database-redis.cpp b/src/database/database-redis.cpp
index a9e549c33..a9a4a37f1 100644
--- a/src/database/database-redis.cpp
+++ b/src/database/database-redis.cpp
@@ -32,6 +32,9 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <hiredis.h>
 #include <cassert>
 
+#if VERSION_MAJOR > 5 || VERSION_MINOR > 9
+#define DEPRECATION_PERIOD_OVER
+#endif
 
 Database_Redis::Database_Redis(Settings &conf)
 {
@@ -66,6 +69,14 @@ Database_Redis::Database_Redis(Settings &conf)
 		}
 		freeReplyObject(reply);
 	}
+
+	warningstream << "/!\\ You are using the deprecated redis backend. "
+#ifdef DEPRECATION_PERIOD_OVER
+		<< "This backend is only still supported for migrations. /!\\\n"
+#else
+		<< "This backend will become read-only in the next release. /!\\\n"
+#endif
+		<< "Please migrate to SQLite3 or PostgreSQL instead." << std::endl;
 }
 
 Database_Redis::~Database_Redis()
@@ -73,16 +84,22 @@ Database_Redis::~Database_Redis()
 	redisFree(ctx);
 }
 
-void Database_Redis::beginSave() {
+void Database_Redis::beginSave()
+{
+#ifdef DEPRECATION_PERIOD_OVER
+	throw DatabaseException("Redis backend is read-only, see deprecation notice.");
+#else
 	redisReply *reply = static_cast<redisReply *>(redisCommand(ctx, "MULTI"));
 	if (!reply) {
 		throw DatabaseException(std::string(
 			"Redis command 'MULTI' failed: ") + ctx->errstr);
 	}
 	freeReplyObject(reply);
+#endif
 }
 
-void Database_Redis::endSave() {
+void Database_Redis::endSave()
+{
 	redisReply *reply = static_cast<redisReply *>(redisCommand(ctx, "EXEC"));
 	if (!reply) {
 		throw DatabaseException(std::string(