Fix SETNX and MSETNX commands can't guarantee atomicity (apache#337)

ShooterIT · Sep 9, 2021 · 8a6ddab · 8a6ddab
1 parent 0e31f8e
commit 8a6ddab
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Showing 2 changed files with 4 additions and 1 deletion.
diff --git a/src/redis_cmd.cc b/src/redis_cmd.cc
@@ -4321,7 +4321,7 @@ CommandAttributes redisCommandTable[] = {
     ADD_CMD("setex", 4, "write", 1, 1, 1, CommandSetEX),
     ADD_CMD("psetex", 4, "write", 1, 1, 1, CommandPSetEX),
     ADD_CMD("setnx", 3, "write", 1, 1, 1, CommandSetNX),
-    ADD_CMD("msetnx", -3, "write", 1, -1, 2, CommandMSetNX),
+    ADD_CMD("msetnx", -3, "write exclusive", 1, -1, 2, CommandMSetNX),
     ADD_CMD("mset", -3, "write", 1, -1, 2, CommandMSet),
     ADD_CMD("incrby", 3, "write", 1, 1, 1, CommandIncrBy),
     ADD_CMD("incrbyfloat", 3, "write", 1, 1, 1, CommandIncrByFloat),

diff --git a/src/redis_string.cc b/src/redis_string.cc
@@ -354,6 +354,9 @@ rocksdb::Status String::MSetNX(const std::vector<StringPair> &pairs, int ttl, in
   for (StringPair pair : pairs) {
     AppendNamespacePrefix(pair.key, &ns_key);
     LockGuard guard(storage_->GetLockManager(), ns_key);
+    if (Exists({pair.key}, &exists).ok() && exists == 1) {
+      return rocksdb::Status::OK();
+    }
     std::string bytes;
     Metadata metadata(kRedisString, false);
     metadata.expire = expire;