I am learning Redis and I am blocked with the pipelining concept, I am trying to send instruction to my redis server
Do to so I using a socket whitch will connect to the redis server I am using.
Here is my code (I am French so some words will be in french)
def send(MESSAGE):
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((TCP_IP, TCP_PORT))
s.send(MESSAGE)
data = s.recv(BUFFER_SIZE)
s.close()
print "Envoi requete PC:", MESSAGE
return data
And here is the way I am using the pipelining :
instruction ='SET compteur 0'
donnee = instruction.encode('utf-8') + '\x0D\x0A'
print envoie(donnee)
instruction=''
for i in range(200):
instruction = instruction + 'INCR compteur\r\n'
donnee = instruction.encode('utf-8') + '\x0D\x0A'
print send(donnee)
when I do this, the shell gives me the 200 INCR compteur but it is followed with :
:1
:2
:3
:4
....
:185
:186
:187
:188
:189
Does somebody have an explanation ? Also if I use another instruction for example with a GET compteur, I have only 147 +PONG
You can add two commands surround your instraction: MULTI before and EXEC after your instructions. This will guaranty atomicity and get all results of execution your commands. Take a look on transaction documentation.
Please read about pipelining also. There are a lot of useful information here.
In fact I guess your problem is that you could start reading answer before Redis return it.
Although logic of flow submitRequest -> receiveResults looks good, but your code doesn't work in such way because Redis perform operation asynchronically.
In fact, your code reads in next way: send data(instructions) to server-> read some data from socket (result | part of result | nothing?). The problems is we don't wait Redis to complete computation.
I am not good in Python but I guess data = s.recv(BUFFER_SIZE) will read up to 'BUFFER_SIZE' bytes from s if it is present. But if only part of results is present in socket this command return only these part of data. Handling reading from socket is not so trivial operation, as other folks suggest - use already existed libraries - https://redis.io/clients#python