Redis的事件操纵的敕令与实行操纵（代码）【MySQL教程】,redis
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序
本文重要研究一下redis的事件操纵
敕令
multi与exec
敕令行
127.0.0.1:6379> multi OK 127.0.0.1:6379> incr total QUEUED 127.0.0.1:6379> incr len QUEUED 127.0.0.1:6379> exec 1) (integer) 2 2) (integer) 2 127.0.0.1:6379> get total "2" 127.0.0.1:6379> get len "2"
lettuce实例
@Test
public void testMultiExec(){
RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
StatefulRedisConnection<String, String> connection = client.connect();
RedisCommands<String, String> syncCommands = connection.sync();
syncCommands.set("hello","1");
syncCommands.set("world","2");
syncCommands.multi();
syncCommands.incr("hello");
syncCommands.incr("world");
//DefaultTransactionResult[wasRolledBack=false,result=[1, 2, 1, 3, 1]]
TransactionResult transactionResult = syncCommands.exec();
System.out.println(transactionResult);
System.out.println(syncCommands.get("hello"));
System.out.println(syncCommands.get("world"));
}
部份实行
敕令行
127.0.0.1:6379> multi OK 127.0.0.1:6379> set a hello QUEUED 127.0.0.1:6379> set b world QUEUED 127.0.0.1:6379> incr a QUEUED 127.0.0.1:6379> set c part QUEUED 127.0.0.1:6379> exec 1) OK 2) OK 3) (error) ERR value is not an integer or out of range 4) OK 127.0.0.1:6379> get a "hello" 127.0.0.1:6379> get b "world" 127.0.0.1:6379> get c "part"
lettuce实例
@Test
public void testMultiExecError(){
RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
StatefulRedisConnection<String, String> connection = client.connect();
RedisCommands<String, String> syncCommands = connection.sync();
syncCommands.multi();
syncCommands.set("a","hello");
syncCommands.set("b","world");
syncCommands.incr("a");
syncCommands.set("c","part");
//DefaultTransactionResult[wasRolledBack=false,result=[OK, OK, io.lettuce.core.RedisCommandExecutionException: ERR value is not an integer or out of range, OK, 1]]
TransactionResult transactionResult = syncCommands.exec();
System.out.println(transactionResult);
System.out.println(syncCommands.get("a"));
System.out.println(syncCommands.get("b"));
System.out.println(syncCommands.get("c"));
}
multi与discard
敕令行
127.0.0.1:6379> set sum 1 OK 127.0.0.1:6379> multi OK 127.0.0.1:6379> incr sum QUEUED 127.0.0.1:6379> discard OK 127.0.0.1:6379> get sum "1"
lettuce实例
@Test
public void testMultiDiscard(){
RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
StatefulRedisConnection<String, String> connection = client.connect();
RedisCommands<String, String> syncCommands = connection.sync();
syncCommands.incr("key1");
syncCommands.multi();
syncCommands.incr("key1");
//须要有multi才够实行discard，胜利返回OK
String result = syncCommands.discard();
System.out.println(result);
System.out.println(syncCommands.get("key1"));
}
check and set
@Test
public void testWatch(){
RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
StatefulRedisConnection<String, String> connection = client.connect();
RedisCommands<String, String> syncCommands = connection.sync();
String key = "key";
syncCommands.watch(key);
//another connection
StatefulRedisConnection<String, String> conn2 = client.connect();
RedisCommands<String, String> syncCommands2 = conn2.sync();
syncCommands2.set(key, "a");
syncCommands.multi();
syncCommands.append(key, "b");
//DefaultTransactionResult [wasRolledBack=true, responses=0]
TransactionResult transactionResult = syncCommands.exec();
System.out.println(transactionResult);
System.out.println(syncCommands.get(key));
}
小结
reids供应multi exec/discard指令，相似open commit/rollback transaction，不过exec碰到范例操纵等错误时不会滚，该胜利实行的敕令照样胜利实行，该失利的照样失利
multi exec保证的是，只需exec敕令有实行胜利，则事件中一系列的敕令都能实行，假如exec由于收集等题目，server端没有接收到，则事件中的一系列敕令都不会被实行
discard须要在有挪用multi的前提下才运用，该敕令会清空事件行列守候实行的敕令
redis供应watch指令，能够合营multi exec来运用，能够完成相似数据库的乐观锁的机制，一旦watch的key被其他client有更新，则全部exec操纵失利
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