From 9f772cc23744804fc4b5da2aa7985c4c512abf55 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Tue, 27 Sep 2011 15:30:31 +0200
Subject: [PATCH] Return errors if a write command is called inside a Lua
script after a random command was called. See
https://github.com/antirez/redis/issues/95 for more information.
---
src/redis.h | 2 ++
src/scripting.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/src/redis.h b/src/redis.h
index 03260264..ec982ee9 100644
--- a/src/redis.h
+++ b/src/redis.h
@@ -623,6 +623,8 @@ struct redisServer {
dict *lua_scripts; /* A dictionary of SHA1 -> Lua scripts */
long long lua_time_limit;
long long lua_time_start;
+ int lua_random_dirty; /* True if a random command was called during the
+ exection of the current script. */
};
typedef struct pubsubPattern {
diff --git a/src/scripting.c b/src/scripting.c
index 0c18d916..f62e5c29 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -180,6 +180,14 @@ int luaRedisCommand(lua_State *lua) {
goto cleanup;
}
+ if (cmd->flags & REDIS_CMD_WRITE && server.lua_random_dirty) {
+ luaPushError(lua,
+ "Write commands not allowed after non deterministic commands");
+ goto cleanup;
+ }
+
+ if (cmd->flags & REDIS_CMD_RANDOM) server.lua_random_dirty = 1;
+
/* Run the command */
cmd->proc(c);
@@ -425,6 +433,16 @@ void evalGenericCommand(redisClient *c, int evalsha) {
* not affected by external state. */
redisSrand48(0);
+ /* We set this flag to zero to remember that so far no random command
+ * was called. This way we can allow the user to call commands like
+ * SRANDMEMBER or RANDOMKEY from Lua scripts as far as no write command
+ * is called (otherwise the replication and AOF would end with non
+ * deterministic sequences).
+ *
+ * Thanks to this flag we'll raise an error every time a write command
+ * is called after a random command was used. */
+ server.lua_random_dirty = 0;
+
/* Get the number of arguments that are keys */
if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
return;
--
2.47.2