Returns a cached value or computes and caches it with a callback.
What Is apcu_entry() in PHP?
Returns a cached value or computes and caches it with a callback.
Its syntax is:
apcu_entry(string $key, callable $callback, int $ttl = 0): mixedParameters:
$key— Accepted as string; required argument.$callback— Accepted as callable; required argument.$ttl— Accepted as int; optional default 0.
Return type: mixed. The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
Availability: Requires APCu enabled for the current PHP SAPI.
Example 1: Basic Usage
<?php
$result = apcu_entry("answer", fn() => 42, 60);
echo $result;
Result: Results and availability depend on the current PHP process, system permissions, cache, filesystem or installed locale. The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
Example 2: A Different Input
<?php
$result = apcu_entry("greeting", fn() => strtoupper("hello"), 60);
echo $result;
Result: Results and availability depend on the current PHP process, system permissions, cache, filesystem or installed locale. The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
Practical Example: Applying It in a Program
<?php
$cacheKey = "site:menu";
$menu = apcu_entry($cacheKey, function () { return ["Home", "Guides", "About"]; }, 120);
print_r($menu);
Result: Results and availability depend on the current PHP process, system permissions, cache, filesystem or installed locale. The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
Important Behavior and Edge Cases
- Key behavior: The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
- Environment: Requires APCu enabled for the current PHP SAPI.
Comparison With Related Functions
| Function | Purpose |
|---|---|
apcu_entry() | returns a cached value or computes and caches it with a callback. |
apcu_fetch() | apcu_fetch() reads an existing value; apcu_entry() can compute and cache a missing value using a callback. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Ignoring this behavior: The callback is run only when the cache needs a value | The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request. |
Key Takeaways
- returns a cached value or computes and caches it with a callback.
- The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.
- Requires APCu enabled for the current PHP SAPI.
Summary: The callback is run only when the cache needs a value. Avoid lengthy callbacks and do not assume the callback executes on each request.