PHP WinCache 函数 Adds a variable in user cache only if variable does not already exist in the cache

说明

wincache_ucache_add ( string $key , mixed $value [, int $ttl = 0 ] ) : bool

wincache_ucache_add ( array $values [, mixed $unused = NULL [, int $ttl = 0 ]] ) : bool

Adds a variable in user cache, only if this variable doesn't already exist in the cache. The added variable remains in the user cache unless its time to live expires or it is deleted by using wincache_ucache_delete() or wincache_ucache_clear() functions.

参数

key: Store the variable using this key name. If a variable with same key is already present the function will fail and return FALSE. key is case sensitive. To override the value even if key is present use wincache_ucache_set() function instad. key can also take array of name => value pairs where names will be used as keys. This can be used to add multiple values in the cache in one operation, thus avoiding race condition.
value: Value of a variable to store. Value supports all data types except resources, such as file handles. This paramter is ignored if first argument is an array. A general guidance is to pass NULL as value while using array as key. If value is an object, or an array containing objects, then the objects will be serialized. See __sleep() for details on serializing objects.
values: Associative array of keys and values.
ttl: Time for the variable to live in the cache in seconds. After the value specified in ttl has passed the stored variable will be deleted from the cache. This parameter takes a default value of 0 which means the variable will stay in the cache unless explicitly deleted by using wincache_ucache_delete() or wincache_ucache_clear() functions.

返回值

If key is string, the function returns TRUE on success and FALSE on failure.

If key is an array, the function returns:

If all the name => value pairs in the array can be set, function returns an empty array;
If all the name => value pairs in the array cannot be set, function returns FALSE;
If some can be set while others cannot, function returns an array with name=>value pair for which the addition failed in the user cache.

范例

Example #1 wincache_ucache_add() with key as a string

 <?php
$bar = 'BAR';
var_dump(wincache_ucache_add('foo', $bar));
var_dump(wincache_ucache_add('foo', $bar));
var_dump(wincache_ucache_get('foo'));
?>

以上例程会输出：

bool(true)
bool(false)
string(3) "BAR"

Example #2 wincache_ucache_add() with key as an array

 <?php
$colors_array = array('green' => '5', 'Blue' => '6', 'yellow' => '7', 'cyan' => '8');
var_dump(wincache_ucache_add($colors_array));
var_dump(wincache_ucache_add($colors_array));
var_dump(wincache_ucache_get('Blue'));
?>

以上例程会输出：

array(0) { } 
array(4) { 
  ["green"]=> int(-1) 
  ["Blue"]=> int(-1) 
  ["yellow"]=> int(-1) 
  ["cyan"]=> int(-1) 
} 
string(1) "6"

参见

wincache_ucache_set() - Adds a variable in user cache and overwrites a variable if it already exists in the cache
wincache_ucache_get() - Gets a variable stored in the user cache
wincache_ucache_delete() - Deletes variables from the user cache
wincache_ucache_clear() - Deletes entire content of the user cache
wincache_ucache_exists() - Checks if a variable exists in the user cache
wincache_ucache_meminfo() - Retrieves information about user cache memory usage
wincache_ucache_info() - Retrieves information about data stored in the user cache
__sleep()