Explanation of memcache in php

For details about memcache in php, memcahe is a distributed storage system, which is mainly reflected in the absence of connection between servers and the maintenance of a hash table through memory, the hash table is mainly stored in key-value pairs, which is a cs software package.

Key	Value
Mystr	"Abc"
Myarr	Array ("aa", "cc ");
Object	Object value

Working Principle

Memcache software, memcached

Memcached runs in one or more services as a daemon and operates and connects to the customer service end at any time.

About memcache installation

Installation in linux

Libevent-based events
Linux
When installing libevent
./Configure-with-libevent =/usr
Make & make install

Install memcached
./Configure-with-libevent =/usr

Make & make install

Start Memcahced-d-m 128-l 192.168.1.111-p 11211-u root
Stop: kill 'cat/tmp/memcached. Pi ';
Killall memcached

Windows
Memcahced.exe-d install [uninstall]
Memcached.exe-d-m 50-l 127.0.0.1-p 11211 start

, Memcached server management (start)
Basic settings of memcached:
-P listening port
-L connected IP address. the default value is local
-D start: start the memcached service.
-D restart: restart the memcached service.
-D stop | shutdown the running memcached service
-D install the memcached service
-D uninstall memcached service
-U runs as the identity (only valid when running as root)
-MB maximum memory usage, in MB. The default value is 64 MB. The maximum value is 2 GB.
-An error is returned when M memory is used up, instead of deleting items.
-C: maximum number of simultaneous connections. the default value is 1024.
-F block size growth factor, default value: 1.25
-N: Minimum allocation space. the default value of key + value + flags is 48.
-H Show Help

VII. how to traverse memcache

8. use Memcached in a PHP program
A. install Memcache extension in PHP

Process-oriented

Object-oriented approach

Where does B use memcache in PHP?

1. The data read from the database (select) is processed using memcache

II. Use in session control sessions

C instance

9. Memcache security (preventing access from others)

1. intranet
2. set a fire wall
Iptables-a input-p tcp-s 192.168.1.111-dport 11211-j ACCEPT
Iptables-a input-p udp-s 192.168.1.111-dpost 11211-j ACCEPT


Install. then start memcached-d start

Command	Description	Example
Get	Reads a value	Get mykey
Set	Set a key unconditionally	Set mykey 0 60 5
Add	Add a new key	Add newkey 0 60 5
Replace	Overwrite existing key	Replace key 0 60 5
Append	Append data to existing key	Append key 0 60 15
Prepend	Prepend data to existing key	Prepend key 0 60 15
Incr	Increments numerical key value by given number	Incr mykey 2
Decr	Decrements numerical key value by given number	Decr mykey 5
Delete	Deletes an existing key	Delete mykey
Flush_all	Invalidate specific items immediately	Flush_all
Invalidate all items in n seconds	Flush_all 900
Stats	Prints general statistics	Stats
Prints memory statistics	Stats slabs
Prints memory statistics	Stats malloc
Print higher level allocation statistics	Stats items
	Stats detail
	Stats sizes
Resets statistics	Stats reset
Version	Prints server version.	Version
Verbosity	Increases log level	Verbosity
Quit	Terminate telnet session	Quit

Pid	Memcache server process ID
Uptime	Number of seconds that the server has run
Time	Current unix timestamp of the server
Version	Memcache version
Pointer_size	Pointer size of the current operating system (32-bit system is generally 32bit)
Rusage_user	Cumulative user time of the process
Rusage_system	Cumulative system time of processes
Curr_items	Number of items currently stored on the server
Total_items	Total number of items stored after Server startup
Bytes	Number of bytes occupied by items stored on the current server
Curr_connections	Number of currently opened connections
Total_connections	Number of connections that have been opened since the server is started
Connection_structures	Number of connections allocated by the server
Pai_get	Total get Command (get) requests
Performance_set	Total number of set command (save) requests
Get_hits	Total hits
Get_misses	Total number of missed hits
Evictions	Number of items deleted to get idle memory (the old items need to be deleted after the space allocated to memcache is full to get the space allocated to the new items)
Bytes_read	Total number of read bytes (number of request bytes)
Bytes_written	Total number of sent bytes (number of returned bytes)
Limit_maxbytes	Memory size (bytes) allocated to memcache)
Threads	Current thread count

Pid memcache server process ID
Number of seconds that the uptime server has run
Current unix timestamp of the time server
Version memcache version
Pointer_size pointer size of the current operating system (32-bit systems are generally 32bit)
Cumulative user time of the rusage_user process
Cumulative system time of the rusage_system process
Number of currently stored items on the curr_items server
Total number of items stored after total_items is started from the server
Bytes the number of bytes occupied by the current server storage items
Curr_connections current number of opened connections
Total_connections number of connections that have been opened since the server was started
Connection_structures server-assigned connection constructor count
Cmd_get command (get) Total number of requests
Cmd_set set command (save) Total number of requests
Total get_hits hits
Total number of get_misses missed
The number of items deleted by evictions to get idle memory (after the space allocated to memcache is used up, you need to delete the old items to get the space allocated to the new items)
Bytes_read total number of read bytes (number of request bytes)
Bytes_written total number of sent bytes (number of result bytes)
The memory size (in bytes) allocated to memcache by limit_maxbytes)
Threads current thread count


For more information, see "LXXXIV. Memcache Functions" in the PHP Manual.
Common Memcache object-oriented interfaces include:
Memcache: connect -- open a connection to Memcache
Memcache: pconnect -- open a persistent connection to Memcache
Memcache: close -- close a Memcache connection
Memcache: set -- save data to the Memcache server
Memcache: get -- extract data stored on the Memcache server
Memcache: replace -- replace a project that already exists on the Memcache server (similar to Memcache: set)
Memcache: delete -- delete a saved project from the Memcache server
Memcache: flush -- refresh the items saved on all Memcache servers (similar to deleting all saved items)
Memcache: getStats -- get the running status of the current Memcache server
Memcache: addServer -- add a server to a distributed server

Use php to operate memcache

$ Mem = new Memcache;

$ Mem-> connect ("localhost", 11211 );

/*
* Note:
* 1. install the same project twice. the key must have a prefix.
*
*
*/

$ SQL = "select * from shops ";
$ Key = substr (md5 ($ SQL), 10, 8 );

$ Data = $ mem-> get ($ key );

If (! $ Data ){

$ Mysqli = new mysqli ("localhost", "root", "123456", "xsphpdb ");

$ Result = $ mysqli-> query ($ SQL );

$ Data = array ();

While ($ row = $ result-> Fetch_assoc ()){
$ Data [] = $ row;
}

$ Result-> free ();
$ Mysqli-> close ();

$ Mem-> set ($ key, $ data, memcache_compute, 3600 );

Echo $ SQL;

}
Echo'

';
    print_r($data);
    echo '

';

$ Mem-> close ();