這篇文章帶給大家的內容是關於Redis的事務操作的命令與執行操作（程式碼），有一定的參考價值，有需要的朋友可以參考一下，希望對你有幫助。
序
本文主要研究redis的事務操作
指令
multi與exec
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"
登入後複製
@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"));
}登入後複製
部分執行
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"
登入後複製
@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"));
}登入後複製
multi與discard
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"
登入後複製
@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");
//需要有multi才可以执行discard，成功返回OK
String result = syncCommands.discard();
System.out.println(result);
System.out.println(syncCommands.get("key1"));
}登入後複製
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));
}登入後複製
小結
-
reids提供multi exec/discard指令，類似open commit/rollback transaction，不過exec遇到類型操作等錯誤時不會滾，該成功執行的指令還是成功執行，該失敗的還是失敗
-
multi exec保證的是，只要exec指令有執行成功，則交易中一系列的指令都能執行，如果exec因為網路等問題，server端沒有接收到，則事務中的一系列指令都不會被執行
-
discard需要在有呼叫multi的前提下才能使用，而該指令會清空交易佇列等待執行的指令
-
redis提供watch指令，可以配合multi exec來使用，可以實現類似資料庫的樂觀鎖的機制，一旦watch的key被其他client有更新，則整個exec操作失敗
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