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# Redisson
## 配置
### 编程式配置
可以通过创建Config对象来显式配置redisson，配置示例如下：
```java
Config config = new Config();
config.setTransportMode(TransportMode.EPOLL);
config.useClusterServers()
// use "rediss://" for SSL connection
.addNodeAddress("perredis://127.0.0.1:7181");
RedissonClient redisson = Redisson.create(config);
```
### yml Configuration
也可以通过yml文件格式来对redisson进行配置：
```java
Config config = Config.fromYAML(new File("config-file.yaml"));
RedissonClient redisson = Redisson.create(config);
```
可以通过config.toYAML方法将config转化为yaml格式：
```java
Config config = new Config();
// ... many settings are set here
String yamlFormat = config.toYAML();
```
yml格式中可以引入环境变量
```yml
singleServerConfig:
address: "redis://127.0.0.1:${REDIS_PORT}"
```
### Common Settings
如下设置用于配置config对象，并且适用于各种redis模式
#### codec
默认值：org.redisson.codec.Kryo5Codec
#### connectionListener
默认值：null
connection listener，当redisson连接到redis-server或与redis-server断开连接时被触发
#### nettyThreads
默认值：32
redisson所有redis client共享的线程总数。netty thread用于redis相应的解码和命令的发送。
#### transportMode
默认值：TransportMode.NIO
可选的值如下：
- TransportMode.NIO（默认）
- TransportMode.EPOLL
- TransportMode.KQUEUE
#### threads
由Rtopic object listener所共享的线程数量
#### lockWatchdogTimeout
默认值：30000
RLock watchdog timeout，单位为ms。该参数仅当RLock在获取时没有指定leaseTimeout时使用。当watchdog没有延长持有锁时间到下一个watchdogTimeout间隔时，当前watchdogTimeout到期后锁会过期。watchdog避免了由于客户端崩溃或其他原因造成一直持有锁的情况。
### Mode
#### single instance mode
可以通过如下方式来配置单实例模式：
```java
// connects to 127.0.0.1:6379 by default
RedissonClient redisson = Redisson.create();
Config config = new Config();
config.useSingleServer().setAddress("redis://myredisserver:6379");
RedissonClient redisson = Redisson.create(config);
```
yml配置单实例模式如下：
```yaml
singleServerConfig:
idleConnectionTimeout: 10000
connectTimeout: 10000
timeout: 3000
retryAttempts: 3
retryInterval: 1500
password: null
subscriptionsPerConnection: 5
clientName: null
address: "redis://127.0.0.1:6379"
subscriptionConnectionMinimumIdleSize: 1
subscriptionConnectionPoolSize: 50
connectionMinimumIdleSize: 24
connectionPoolSize: 64
database: 0
dnsMonitoringInterval: 5000
threads: 16
nettyThreads: 32
codec: !<org.redisson.codec.Kryo5Codec> {}
transportMode: "NIO"
```
## Operation Execution
redisson支持自动重试策略，并且在每次尝试时都会发送命令。重试策略通过retryAttempts（默认情况下为3）、retryInterval（默认情况下为1000ms）来设置。多次尝试之间间隔retryInterval。
redisson实例是线程安全的，如下是RAtomicLong对象的使用示例：
```java
RedissonClient client = Redisson.create(config);
RAtomicLong longObject = client.getAtomicLong('myLong');
// sync way
longObject.compareAndSet(3, 401);
// async way
RFuture<Boolean> result = longObject.compareAndSetAsync(3, 401);
RedissonReactiveClient client = Redisson.createReactive(config);
RAtomicLongReactive longObject = client.getAtomicLong('myLong');
// reactive way
Mono<Boolean> result = longObject.compareAndSet(3, 401);
RedissonRxClient client = Redisson.createRx(config);
RAtomicLongRx longObject= client.getAtomicLong("myLong");
// RxJava2 way
Flowable<Boolean result = longObject.compareAndSet(3, 401);
```
### Async方式
大多数redisson object继承了异步接口，可以调用异步方法实现异步操作，如下：
```java
// RAtomicLong extends RAtomicLongAsync
RAtomicLongAsync longObject = client.getAtomicLong("myLong");
RFuture<Boolean> future = longObject.compareAndSetAsync(1, 401);
```
RFuture对象继承了Future接口和CompletionStage接口，可以像CompleteableFuture一样使用：
```java
future.whenComplete((res, exception) -> {
// handle both result and exception
});
// or
future.thenAccept(res -> {
// handle result
}).exceptionally(exception -> {
// handle exception
});
```
因该避免在future listener中使用同步方法，这样可能会造成redis请求/相应处理时的错误，应使用如下方式执行：
```java
future.whenCompleteAsync((res, exception) -> {
// handle both result and exception
}, executor);
// or
future.thenAcceptAsync(res -> {
// handle result
}, executor).exceptionallyAsync(exception -> {
// handle exception
}, executor);
```
## Redisson Object的公共操作
所有redisson object都实现了RObject和RExpiration接口，使用示例如下：
```java
RObject object = redisson.get...()
object.sizeInMemory();
object.delete();
object.rename("newname");
object.isExists();
// catch expired event
object.addListener(new ExpiredObjectListener() {
...
});
// catch delete event
object.addListener(new DeletedObjectListener() {
...
});
```
redisson object的name属性即是在redis中的key：
```java
RMap map = redisson.getMap("mymap");
map.getName(); // = mymap
```
和redis key相关的所有操作都通过RKeys接口暴露，使用示例如下：
```java
RKeys keys = redisson.getKeys();
Iterable<String> allKeys = keys.getKeys();
Iterable<String> foundedKeys = keys.getKeysByPattern('key*');
long numOfDeletedKeys = keys.delete("obj1", "obj2", "obj3");
long deletedKeysAmount = keys.deleteByPattern("test?");
String randomKey = keys.randomKey();
long keysAmount = keys.count();
keys.flushall();
keys.flushdb();
```
## 分布式对象
### object holder
#### RBucket
RBucket的java实现类是一个hodler，可以持有任何类型的java对象。RBucket的大小限制为512MB.
RBucket的使用示例如下所示：
```java
RBucket<AnyObject> bucket = redisson.getBucket("anyObject");
bucket.set(new AnyObject(1));
AnyObject obj = bucket.get();
bucket.trySet(new AnyObject(3));
bucket.compareAndSet(new AnyObject(4), new AnyObject(5));
bucket.getAndSet(new AnyObject(6));
```
#### RBuckets
可以通过RBuckets对象来操作多个RBucket对象，RBuckets使用示例如下：
```java
RBuckets buckets = redisson.getBuckets();
// get all bucket values
Map<String, V> loadedBuckets = buckets.get("myBucket1", "myBucket2", "myBucket3");
Map<String, Object> map = new HashMap<>();
map.put("myBucket1", new MyObject());
map.put("myBucket2", new MyObject());
// sets all or nothing if some bucket is already exists
buckets.trySet(map);
// store all at once
buckets.set(map);
```
### Binary Stream Holder
RBinaryStream类型的对象用于存储字节序列。RBinaryStream实现了RBucket接口，并且其大小限制也是512MB.
RBinaryStream的使用示例如下：
```java
RBinaryStream stream = redisson.getBinaryStream("anyStream");
byte[] content = ...
stream.set(content);
stream.getAndSet(content);
stream.trySet(content);
stream.compareAndSet(oldContent, content);
```
RBinaryStream可以和InputStream与OutputStream混用，使用如下：
```java
RBinaryStream stream = redisson.getBinaryStream("anyStream");
InputStream is = stream.getInputStream();
byte[] readBuffer = ...
is.read(readBuffer);
OutputStream os = stream.getOuputStream();
byte[] contentToWrite = ...
os.write(contentToWrite);
```
### BitSet
RBitSet实现提供了和java中BitSet类似的api，其大小限制是4 294 967 295 bits.
RBitSet使用如下所示：
```java
RBitSet set = redisson.getBitSet("simpleBitset");
set.set(0, true);
set.set(1812, false);
set.clear(0);
set.and("anotherBitset");
set.xor("anotherBitset");
```
### AtomicLong
RAtomicLong实现提供了和java中AtomicLong类似的api，其使用类似如下：
```java
RAtomicLong atomicLong = redisson.getAtomicLong("myAtomicLong");
atomicLong.set(3);
atomicLong.incrementAndGet();
atomicLong.get();
```
### AtomicDouble
RAtomicDouble实现提供了和java中AtomicDouble类似的api，其使用示例如下：
```java
RAtomicDouble atomicDouble = redisson.getAtomicDouble("myAtomicDouble");
atomicDouble.set(2.81);
atomicDouble.addAndGet(4.11);
atomicDouble.get();
```
### Topic
RTopic实现提供了发布/订阅机制，其允许订阅由同名RTopic对象发布的事件。
当重新连接到redis或redis错误切换之后，listener会被重新订阅，在重新订阅之前，所有被发布的消息都会丢失。
RTopic的使用如下所示：
```java
RTopic topic = redisson.getTopic("myTopic");
int listenerId = topic.addListener(SomeObject.class, new MessageListener<SomeObject>() {
@Override
public void onMessage(String channel, SomeObject message) {
//...
}
});
// in other thread or JVM
RTopic topic = redisson.getTopic("myTopic");
long clientsReceivedMessage = topic.publish(new SomeObject());
```
### Reliable Topic
RRelieableTopic在实现发布/订阅模式的情况下，还实现了消息的可靠传输。当redis连接断开的情况下，所有消息都会被存储，当重新连接到redis时，消息会被重新传送。
每个RReliableTopic对象实例都由一个watchdog，当第一个listener注册之后，watchdog就会被启用。当订阅者超过reliableTopicWatchdogTimeout之后，且watchdog没有为其延续过期时间，那么订阅将会超时。（该机制是为了防止client长时间崩溃之后存储的消息持续增长）。
**当重新连接到redis之后，listener会被重新注册**
```java
RReliableTopic topic = redisson.getReliableTopic("anyTopic");
topic.addListener(SomeObject.class, new MessageListener<SomeObject>() {
@Override
public void onMessage(CharSequence channel, SomeObject message) {
//...
}
});
// in other thread or JVM
RReliableTopic topic = redisson.getReliableTopic("anyTopic");
long subscribersReceivedMessage = topic.publish(new SomeObject());
```
### Topic Pattern
RPatternTopic允许订阅多个Rtopic，在重新连接到redis或redis错误切换之后，listener会被重新订阅。
Pattern使用如下：
- topic?： subscribes to topic1, topicA ...
- topic?_my： subscribes to topic_my, topic123_my, topicTEST_my ...
- topic[ae]： subscribes to topica and topice only
使用示例如下：
```java
// subscribe to all topics by `topic*` pattern
RPatternTopic patternTopic = redisson.getPatternTopic("topic*");
int listenerId = patternTopic.addListener(Message.class, new PatternMessageListener<Message>() {
@Override
public void onMessage(String pattern, String channel, Message msg) {
//...
}
});
```
### Bloom Filter
RBloomFilter中最多含有2^32个bit。
在使用之前，必须通过tryInit(expectedInsertions, falseProbability)来初始化capacity。
RBloomFilter使用示例如下：
```java
RBloomFilter<SomeObject> bloomFilter = redisson.getBloomFilter("sample");
// initialize bloom filter with
// expectedInsertions = 55000000
// falseProbability = 0.03
bloomFilter.tryInit(55000000L, 0.03);
bloomFilter.add(new SomeObject("field1Value", "field2Value"));
bloomFilter.add(new SomeObject("field5Value", "field8Value"));
bloomFilter.contains(new SomeObject("field1Value", "field8Value"));
bloomFilter.count();
```
### HyperLogLog
RHyperLogLog能以较低的空间维护大数量的项目，计算其去重后的数量，其使用如下所示：
```java
RHyperLogLog<Integer> log = redisson.getHyperLogLog("log");
log.add(1);
log.add(2);
log.add(3);
log.count();
```
### LongAdder
RLongAdder提供了java中LongAdder的实现，其在client端维护了LongAdder，增加和减少的性能较AtomicLong来说都有极大的提升（至多可提升12000倍）。其使用如下所示：
```java
RLongAdder atomicLong = redisson.getLongAdder("myLongAdder");
atomicLong.add(12);
atomicLong.increment();
atomicLong.decrement();
atomicLong.sum();
```
当LongAdder不再使用之后，应该调用destroy方法手动进行销毁：
```java
RLongAdder atomicLong = ...
atomicLong.destroy();
```
### DoubleAdder
RDoubleAdder提供了java中DoubleAdder的分布式实现，其性能相对于AtomicDouble也有很大提升。
其使用如下所示：
```java
RLongDouble atomicDouble = redisson.getLongDouble("myLongDouble");
atomicDouble.add(12);
atomicDouble.increment();
atomicDouble.decrement();
atomicDouble.sum();
```
### id generator
RIdGenerator实现允许产生唯一的id，但其生成算法不是简单的递增，而是在第一次请求时，一系列id就已经被分配并且缓存到java端，直到其用完。该方法能够减少和redis的通信次数，产生id的速率比RAtomicLong快。
默认情况下allocate size是2000，并且值从0开始。
RIdGenerator的使用如下所示：
```java
RIdGenerator generator = redisson.getIdGenerator("generator");
// Initialize with start value = 12 and allocation size = 20000
generator.tryInit(12, 20000);
long id = generator.nextId();
```
### Json Object Holder
RJsonBucket类型用于存储json数据，通过redis 的JSON.*命令来实现。Json数据通过JsonCodec来进行编码和解码。可用的实现是org.redisson.codec.JacksonCodec。
#### local cache
redisson提供了带有本地缓存的json object holder版本。
local cache用于加速读取操作从而较少网络请求次数，其将整个json对象缓存在redisson侧，执行读取操作比无缓存快45倍。
| redission client method name | local cache | Ultra-fast read/write |
| :-: | :-: | :-: |
| getJsonBucket() open-source version | false | false |
| getJsonBucket() Redisson PRO version | false | true |
| getLocalCachedJsonBucket() Redisson PRO version | true | true |
RJsonBucket使用如下所示：
```java
RJsonBucket<AnyObject> bucket = redisson.getJsonBucket("anyObject", new JacksonCodec<>(AnyObject.class));
bucket.set(new AnyObject(1));
AnyObject obj = bucket.get();
bucket.trySet(new AnyObject(3));
bucket.compareAndSet(new AnyObject(4), new AnyObject(5));
bucket.getAndSet(new AnyObject(6));
List<String> values = bucket.get(new JacksonCodec<>(new TypeReference<List<String>>() {}), "values");
long aa = bucket.arrayAppend("$.obj.values", "t3", "t4");
```