阅读redisson相关文档阅读redisson相关文档

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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");
```