Redis Lists: BRPOP

BRPOP key1 [key2 ] timeout

Redis BRPOP command is used to block the connection when there are no elements to pop from any of the given lists or remove and get the last element in a list if available. It is a blocking list pop primitive. An element is popped from the tail of the first list that is non-empty.

Syntax:

BRPOP LIST1 LIST2 .. LISTN TIMEOUT    

Available since

2.0.0.

Return Value

String reply, value of element stored at key or nil

Return Value Type

String

Example: Redis BRPOP

127.0.0.1:6379> RPUSH mycolor1 R G B
(integer) 3
127.0.0.1:6379> RPUSH mycolor2 Y O P
(integer) 3
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor1"
2) "B"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor1"
2) "G"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor1"
2) "R"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor2"
2) "P"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor2"
2) "O"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30
1) "mycolor2"
2) "Y"
127.0.0.1:6379> BRPOP mycolor mycolor1 mycolor2 30

(nil)
(30.04s)

Above example will block the client for 30 seconds to execute any command. If any data comes in the specified key lists then it returns otherwise after 30 seconds nil value is returned.

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