Server Side Scripting - Redisson

LUA Scripting

Redisson provides RScript object to execute Lua script. It has atomicity property and used to process data on Redis or Valkey side. Script could be executed in two modes:

Mode.READ_ONLY scripts are executed as read operation
Mode.READ_WRITE scripts are executed as write operation

One of the follow types returned as a script result object:

ReturnType.BOOLEAN - Boolean type.
ReturnType.INTEGER - Integer type.
ReturnType.MULTI - List type of user defined type.
ReturnType.STATUS - Lua String type.
ReturnType.VALUE - User defined type.
ReturnType.MAPVALUE - Map value type.
ReturnType.MAPVALUELIST - List of Map value type.

Code example:

java

RBucket<String> bucket = redisson.getBucket("foo");
bucket.set("bar");

RScript script = redisson.getScript(StringCodec.INSTANCE);

String r = script.eval(Mode.READ_ONLY,
                       "return redis.call('get', 'foo')", 
                       RScript.ReturnType.VALUE);

// execute the same script stored in Redis or Valkey lua script cache

// load lua script into Redis or Valkey cache to all master instances
String res = script.scriptLoad("return redis.call('get', 'foo')");
// res == 282297a0228f48cd3fc6a55de6316f31422f5d17

// call lua script by sha digest
Future<Object> r1 = redisson.getScript().evalShaAsync(Mode.READ_ONLY,
   "282297a0228f48cd3fc6a55de6316f31422f5d17",
   RScript.ReturnType.VALUE, Collections.emptyList());

Functions

Redisson provides RFunction object to execute Functions. It has atomicity property and used to process data on Redis or Valkey side. Function can be executed in two modes:

Mode.READ executes function as read operation
Mode.WRITE executes function as write operation

One of the follow types returned as a script result object:

ReturnType.BOOLEAN - Boolean type
ReturnType.LONG - Long type
ReturnType.LIST - List type of user defined type.
ReturnType.STRING - plain String type
ReturnType.VALUE - user defined type
ReturnType.MAPVALUE - Map Value type. Codec.getMapValueDecoder() and Codec.getMapValueEncoder() methods are used for data deserialization or serialization
ReturnType.MAPVALUELIST - List type, which consists of objects of Map Value type. Codec.getMapValueDecoder() and Codec.getMapValueEncoder() methods are used for data deserialization or serialization

Code example:

java

RFunction f = redisson.getFunction();

// load function
f.load("lib", "redis.register_function('myfun', function(keys, args) return args[1] end)");

// execute function
String value = f.call(RFunction.Mode.READ, "myfun", RFunction.ReturnType.STRING, Collections.emptyList(), "test");

Code example of Async interface usage:

java

RFunction f = redisson.getFunction();

// load function
RFuture<Void> loadFuture = f.loadAsync("lib", "redis.register_function('myfun', function(keys, args) return args[1] end)");

// execute function
RFuture<String> valueFuture = f.callAsync(RFunction.Mode.READ, "myfun", RFunction.ReturnType.STRING, Collections.emptyList(), "test");

Code example of Reactive interface usage:

java

RedissonReactiveClient redisson = redissonClient.reactive();
RFunctionReactive f = redisson.getFunction();

// load function
Mono<Void> loadMono = f.load("lib", "redis.register_function('myfun', function(keys, args) return args[1] end)");

// execute function
Mono<String> valueMono = f.callAsync(RFunction.Mode.READ, "myfun", RFunction.ReturnType.STRING, Collections.emptyList(), "test");

Code example of RxJava3 interface usage:

java

RedissonRxClient redisson = redissonClient.rxJava();
RFunctionRx f = redisson.getFunction();

// load function
Completable loadMono = f.load("lib", "redis.register_function('myfun', function(keys, args) return args[1] end)");

// execute function
Maybe<String> valueMono = f.callAsync(RFunction.Mode.READ, "myfun", RFunction.ReturnType.STRING, Collections.emptyList(), "test");