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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");
+```