Redis installation

1, download, decompress, install

[root@incisor ~]# yum install -y gcc gcc-c++ make cmake
[root@incisor ~]Wget # http://download.redis.io/releases/redis-5.0.3.tar.gz
[root@incisor ~]# tar - ZXVF redis - 5.0.3. Tar. Gz
[root@incisor ~]# CD redis - 5.0.3[root @ incisor redis - 5.0.3]# make PREFIX=/usr/local/redis install
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1) Copy the utils/redis_init_script file to /etc/init.d/ and rename it Redis

[root @ incisor redis - 5.0.3]# cp -p utils/redis_init_script /etc/init.d/redis[root @ incisor redis - 5.0.3]# vi /etc/init.d/redis
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Modified contents:

REDISPORT=6379  Redis listener port is defined
EXEC=/usr/local/redis/bin/redis-server  # redis The default server execution path
CLIEXEC=/usr/local/redis/bin/redis-cli  # redis-cli startup path
PIDFILE=/var/run/redis_${REDISPORT}.pid

#redis configuration file, so we need to create a directory in /etc to save the redis configuration file, and copy the configuration file to this directory
CONF="/etc/redis/redis.conf"  # redis configuration file
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2) Copy the redis.conf file to /etc/redis/

[root @ incisor redis - 5.0.3]# mkdir /etc/redis[root @ incisor redis - 5.0.3]# cp -p redis.conf /etc/redis/[root @ incisor redis - 5.0.3]# vi /etc/redis/redis.conf
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Modified contents:

bind 127.0.0.1   For remote access, change the IP address to a public IP address
daemonize yes  # change to yes to run as a daemon
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There are only two basic Settings, but I only want to use Redis as a cache, so I don’t need persistence, so I have to change some other Settings, the following Settings are as needed:

loglevel notice  # log level
logfile "/usr/local/redis/log/redis.log"  # Log save path

maxmemory 67108864  Set the maximum memory usage to 64M, as required

databases 1  # set the maximum number of databases

requirepass 12345678  # set password

#save 900 1
#save 300 10
#save 60 10000
save ""  # turn off RDB persistence

appendonly no  # Turn off AOF persistence
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Create log directory /usr/local/redis/log.

3. Add system services

[root@incisor redis]# cd /etc/init.d/
[root@incisor init.d]# chkconfig --add redis
[root@incisor init.d]# chkconfig --level 235 redis on
[root@incisor init.d]# chkconfig --list redis #Redis 0: disabled 1: disabled 2: enabled 3: enabled 4: disabled 5: enabled 6: disabledCopy the code

The chkconfig deletion service is: chkconfig –del [name], for example, chkconfig –del redis.

4. Start and stop Redis

[root@incisor init.d]# service redis start
[root@incisor init.d]# service redis stop
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If bind is set to a public IP address in /etc/redis/redis.conf, run the service redis stop command to stop the process.

The stop command executes the stop function in /etc/init.d/redis.

Among them

$CLIEXEC -p $REDISPORT shutdown
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Is stop Redis task, and $CLIEXEC Redis – namely the cli command, ignore -h parameter, the default is to connect 127.0.0.1, so if the/etc/Redis/Redis in conf bind not 127.0.0.1, Then you need to modify the /etc/init.d/redis file. Modified as follows:

IP = 127.0.0.1/etc/redis/redis
REDISPORT=6379
EXEC=/usr/local/redis/bin/redis-server
CLIEXEC=/usr/local/redis/bin/redis-cli ...... omit$CLIEXEC -h $IP -p $REDISPORT shutdown  -h $IP
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But I generally use their own test, are too lazy to change, directly kill.

5. Access the cli client

[root@incisor ~]# /usr/local/redis/bin/redis-cli -h host -p port -a password
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Python connection Redis

Pip3 install redis

Redis provides two classes redis and StrictRedis for implementing redis server commands. Redis is a subclass of StrictRedis for backward compatibility with older versions of Redis-py. So the Redis class is often used.

Redis connection instances are thread-safe and can be set as a global variable directly.

2. Connect to Redis server

import redis

r = redis.Redis(host='127.0.0.1', port=6379, decode_responses=True)
r.set('skey'.'svalue')
print(r['skey'])
print(r.get('skey'))
print(type(r.get('skey')))  
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Decode_responses =True is required so that value is STR or False is byte.

3. Connection pool

import redis

pool = redis.ConnectionPool(max_connections=10, host='127.0.0.1', port=6379, decode_responses=True)
r = redis.Redis(connection_pool=pool)
r.set('skey'.'svalue')
print(r['skey'])
print(id(r))
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Max_connections: set the maximum number of connections. Here is a document that analyzes the source code of the redis.connectionpool () ConnectionPool, if you are interested: www.u3v3.com/ar/1346.

4. Set the connection pool to the singleton pool.py file

import redis

pool = redis.ConnectionPool(max_connections=10, host='127.0.0.1', port=6379, decode_responses=True)
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Then, the other files import the pool variable so that you can implement a singleton connection pool. Test. Py files

import redis
from pool import pool

r = redis.Redis(connection_pool=pool)
r.set('skey'.'svalue')
print(r['skey'])
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Specific Redis data type, as well as the corresponding method, to view.

Django uses Redis as a cache for relational databases

Pip3 install django-redis

2, set settings.py file to add

CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache"."LOCATION": "Redis: / / 127.0.0.1:6379/0"."OPTIONS": {
            "CLIENT_CLASS": "django_redis.client.DefaultClient"."CONNECTION_POOL_KWARGS": {"max_connections": 10, "decode_responses": True},
            # "PASSWORD": ""}}}Copy the code

Where “LOCATION” represents the connection string and can be set in three ways: redis://[:password]@localhost:6379/0 rediss://[:password]@localhost:6379/0 unix://[:password]@/path/to/spcket.sock? Db =0 db=0 db=0 db=0 db=0 db=0 db=0 db=0 db=0 db=0

“CONNECTION_POOL_KWARGS”: connection pool Settings “max_connections”: maximum number of connections” decode_responses”: write Redis as a string or a byte type if False.

Django-redis uses the connection pool interface of Redis-py. By default, redis-py does not close connections and reuses connections whenever possible. Redis-py is the connection pool of the Redis library.

3. Redis can be accessed in two ways:

1) Use the django.core.cache.cache class, which has huge pits!

from django.core.cache import cache
from django.http import HttpResponse


def hello(request):
    key = 'skey'
    value = 'svalue'
    cache.set(key, value)
    if key in cache:
        return HttpResponse('<h1>{0}: {1}</h1>'.format(key, cache.get(key)))
    else:
        return HttpResponse('
 Not found 
')
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Before this code runs, the decode_responses parameter in CACHES in settings.py needs to be set to False for reasons I don’t get into.

Run this code without any problems, can write and read. But!! What if the key-value was written by another client? If I add key-value through redis-CLI tool, it will not be retrieved through cache.get(key), of course, the skey-value added by this code will not be retrieved through get on client.

The key-value added to this code is as follows:

[root@incisor ~]# / usr/local/redis/bin/redis - cli - h # 127.0.0.1 127.0.0.1, negligible - h parameter127.0.0.1:6379 > keys *# view all keys
1) ":1:skey"
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. Cache.set (key, value) concatenates the string “:1:” before the key. That’s why I call this cache an invisible pit.

2) by get_redis_connection ()

from django_redis import get_redis_connection
from django.http import HttpResponse


def hello(request):
    key = 'skey'
    value = 'svalue'
    conn = get_redis_connection('default')
    conn.set(key, value)
    if conn.get(key):
        return HttpResponse('<h1>{0}: {1}</h1>'.format(key, conn.get(key)))
    else:
        return HttpResponse('
 Not found 
')
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After executing, check the key value with redis-cli:

127.0.0.1:6379 > keys * 1)"skey"
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Now the key is not concatenated, so I use this function a lot.

With get_redis_connection() it is best to set the decode_responses parameter in CACHES in settings.py to True, Also the ‘default’ in conn = get_redis_Connection (‘default’) is the ‘default’ for CACHES in settings.py.