MongoDB&Redis&Zookeeper&Kafka

Redis

概念

　　Redis是NoSQL中比较常典型的一个非关系型数据库，在日常工作中也是最为常见的。Redis是一个由C语言编写的开源的、遵守BSD协议、支持网络、可基于内存亦可持久化的日志型、Key-Value数据库，并提供多种语言的API

　　这里我们引入一下 cookie 和 session ，session 一般是存在于服务器的，每次我们进行操作，都要跟这个 session 值进行校验，如果校验不上，就会重定向登录页。那么如果这个 session 放在普通的关系型数据库内，比如 Mysql ，那么首先读取的速度会相对较慢，而且会占用正常业务逻辑对于数据库的连接池，磁盘 io 等。在这种情况下，那么我们的 session 一般是存在缓存内。那么我们可以用 Redis 来存储这个 session。

安装&启动

1、下载并安装 Redis

　　我们可以使用wget下载，也可以将redis的包下载下来并且导入到linux中

$ wget http://download.redis.io/releases/redis-2.8.17.tar.gz
$ yum install gcc tcl -y
$ tar xzf redis-2.8.8.tar.gz
$ cd redis-4.0.8
$ make 
$ mkdir /usr/local/redis
$ make install PREFIX=/usr/local/redis

2、启动/停止 Redis

./redis-server

redis-cli shutdown

　　默认启动redis使用的是默认配置，端口号为 6379，密码为空。如果需要后台启动的话，可以使用nohup来启动。

nohup redis-server &

　　当然，如果需要指定redis的配置文件，那我们可以在启动命令中指定好配置文件就可以。

nohup redis-server /usr/local/redis/redis.conf &

3、redis.conf 配置

# Protected mode is a layer of security protection, in order to avoid that
# Redis instances left open on the internet are accessed and exploited.
#
# When protected mode is on and if:
#
# 1) The server is not binding explicitly to a set of addresses using the
# "bind" directive.
# 2) No password is configured.
#
# The server only accepts connections from clients connecting from the
# IPv4 and IPv6 loopback addresses 127.0.0.1 and ::1, and from Unix domain
# sockets.
#
# By default protected mode is enabled. You should disable it only if
# you are sure you want clients from other hosts to connect to Redis
# even if no authentication is configured, nor a specific set of interfaces
# are explicitly listed using the "bind" directive.
protected-mode yes ## 保护模式，保护 Redis 不受外网连接

# Accept connections on the specified port, default is 6379 (IANA #815344).
# If port 0 is specified Redis will not listen on a TCP socket.
port 6379 ## Redis 的端口，可自行设置

# Unix socket.
#
# Specify the path for the Unix socket that will be used to listen for
# incoming connections. There is no default, so Redis will not listen
# on a unix socket when not specified.
#
# unixsocket /tmp/redis.sock
# unixsocketperm 700

# Close the connection after a client is idle for N seconds (0 to disable)
timeout 0

# TCP keepalive.
#
# If non-zero, use SO_KEEPALIVE to send TCP ACKs to clients in absence
# of communication. This is useful for two reasons:
#
# 1) Detect dead peers.
# 2) Take the connection alive from the point of view of network
# equipment in the middle.
#
# On Linux, the specified value (in seconds) is the period used to send ACKs.
# Note that to close the connection the double of the time is needed.
# On other kernels the period depends on the kernel configuration.
#
# A reasonable value for this option is 300 seconds, which is the new
# Redis default starting with Redis 3.2.1.
tcp-keepalive 300 ## tcp 连接数

# By default Redis does not run as a daemon. Use 'yes' if you need it.
# Redis默认不是以守护进程的方式运行，可以通过该配置项修改，使用yes启用守护进程
# Note that Redis will write a pid file in /var/run/redis.pid when daemonized.
# 启用守护进程后，Redis会把pid写到一个pidfile中，在/var/run/redis.pid
daemonize yes ## 后台启动

# Set the number of databases. The default database is DB 0, you can select
# a different one on a per-connection basis using SELECT <dbid> where
# dbid is a number between 0 and 'databases'-1
databases 16 ## Redis 到底起多少库

################################ SNAPSHOTTING ################################
#
# Save the DB on disk:
#
# save <seconds> <changes>
#
# Will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
#
# In the example below the behaviour will be to save:
# after 900 sec (15 min) if at least 1 key changed
# after 300 sec (5 min) if at least 10 keys changed
# after 60 sec if at least 10000 keys changed
#
# Note: you can disable saving completely by commenting out all "save" lines.
#
# It is also possible to remove all the previously configured save
# points by adding a save directive with a single empty string argument
# like in the following example:
#
# save ""

save 900 1 ## 900s 内 1 次数据更改操作，存一次数据库
save 300 10 ## 300s 内 10次数据更改操作，存一次数据库
save 60 10000 ## 60s内10000次数据更改操作，存一次数据库

# Compress string objects using LZF when dump .rdb databases?
# For default that's set to 'yes' as it's almost always a win.
# If you want to save some CPU in the saving child set it to 'no' but
# the dataset will likely be bigger if you have compressible values or keys.
rdbcompression yes

# The filename where to dump the DB
dbfilename dump.rdb

# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir ./

　　这里，我们可以创建一个模板配置文件，命名为 redis6380.conf ：

daemonize   yes
pidfile     /usr/local/redis/redis.pid_6380
logfile     /usr/local/redis/redis.log_6380
port        6380
maxmemory   128mb
dir         /usr/local/redis/redis6380　　## 该路径要自己创建
requirepass 123456
appendonly yes
databases 8

　　然后，我们要启动该 Redis 的话，要指定该配置文件，否则会按照 redis.conf 文件启动：

./redis-server redis6380.conf

# ps -ef | grep redis　　## 查看 redis 是否启动以及启动端口
root 13098 1 0 16:40 ? 00:00:00 ./redis-server *:6380
root 13105 13063 0 16:41 pts/1 00:00:00 grep redis

4、连接redis　

　　远程连接redis，可以使用redis自带的工具redis-cli，具体使用方法如下：

redis-cli -h 127.0.0.1 -p 6379 -n 0

 -h <hostname> Server hostname (default: 127.0.0.1).
 -p <port> Server port (default: 6379).
 -a <password> Password to use when connecting to the server.
 --help 显示帮助信息

　　切换数据库：

select 0
select 10

　　利用客户端连接：