First of all we need to understand what is cache ?Cache is collection of items (data) stored in RAM . It is easily accessible . it does not require any I/O operation so its fast also .We use cache to optimize our application response time .
Cache in PHP :-
There are many ways we can use cache in php :-
Cache in PHP :-
There are many ways we can use cache in php :-
1) Memcahce
2) APC
Here I will explain how to use APC .
APC is alternate php cache
It is an extension to php . we can install it by following command .
yum install pcre-devel
yum install apc
Here are some predefined functions we need to use for APC .We can understand many functionalities just by name of the method .
apc_store () -- to store data in cache
apc_fetch() -- to fetch data from cache
apc_delete() -- to delete entries from cache
apc_inc() -- to increase integer value of any cache entry
apc_dec() -- to decrease integer value of any cache entry
Uses of functions :-
apc_store('name','parveen'); //this will store name=’parveen ‘ in cache .
2) APC
Here I will explain how to use APC .
APC is alternate php cache
It is an extension to php . we can install it by following command .
yum install pcre-devel
yum install apc
Here are some predefined functions we need to use for APC .We can understand many functionalities just by name of the method .
apc_store () -- to store data in cache
apc_fetch() -- to fetch data from cache
apc_delete() -- to delete entries from cache
apc_inc() -- to increase integer value of any cache entry
apc_dec() -- to decrease integer value of any cache entry
Uses of functions :-
apc_store('name','parveen'); //this will store name=’parveen ‘ in cache .
apc_store('name','parveen',500); // store in cache for 500 seconds.after that will be auto deleted
echo apc_fetch('name'); // it will return ’parveen’
apc_delete('name') ; // will delete from cache . if we try to fetch now then it will give error
example :-
example :-
apc_store('num',1);
apc_inc('num'); // now num is 2
apc_inc('num',5); //now num is 7
apc_dec('num'); // now num is 6
apc_dec('num',3); //now num is 3
Some points that we need to take care of :-
1) If memory of cache is full then it will delete all cache . so increase max limit size acording to your use . this can be achieved by making some entries in php.ini (php conf file)
2) For better optimization we should set maximum time limit of cache . so that old entries get deleted automatically and free acquired space .
we can write following lines in php.ini file
apc.shm_size="128M" // this will set maximum size of cache to 128MB . default is 32 mb
apc.ttl="1800" // this will set maximum time to live for cache entry . default is unlimited
Simple page visits counter programs using cache :-
$key = 'visit_num';
if(apc_exists($key))
{
apc_inc($key, 1);
}
else
{
$count=1;
apc_store($key, $count);
}
and on hourly basis we can get that count from cache and store it in db . we can do it on daily basis or according to our convenience .
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