ablocks / includes / classes / cache-backend.php

cache-backend.php in aBlocks – Gutenberg Blocks, User Dashboard Builder, Popup Builder, Form Builder & Animation Builder trunk, at includes/classes/cache-backend.php

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1	<?php
2	namespace ABlocks\Classes;
3
4	if ( ! defined( 'ABSPATH' ) ) {
5	exit;
6	}
7
8	/**
9	* Shared cache backend for the Performance Suite.
10	*
11	* Wraps the object cache, falling back to transients, and — more importantly —
12	* lets a feature ask whether caching is actually worth doing before it starts.
13	*
14	* ## Why the distinction matters
15	*
16	* Without a persistent object cache (Redis, Memcached), `wp_cache_*` is
17	* per-request memory only and transients are rows in `wp_options`, so every
18	* read is a database round trip. That is fine when the cached work is
19	* expensive, and actively harmful when it is not.
20	*
21	* Measured here on the block template cache: resolving templates costs 7–10
22	* queries, but caching the result in transients produced more queries than it
23	* saved — 81 per request cached versus 75 uncached — because each lookup adds
24	* its own option reads and has to unserialize large WP_Block_Template objects.
25	* With a persistent object cache the same lookup is an out-of-process fetch
26	* with no database involvement, and the trade flips.
27	*
28	* So features that cache cheap-but-frequent work call
29	* {@see CacheBackend::is_persistent()} and disable themselves when it returns
30	* false, rather than assuming a cache is free.
31	*/
32	class CacheBackend {
33
34	const GROUP = 'ablocks_perf';
35
36	/**
37	* Is a persistent (cross-request, out-of-process) object cache available?
38	*
39	* @return bool
40	*/
41	public static function is_persistent() {
42	return function_exists( 'wp_using_ext_object_cache' ) && wp_using_ext_object_cache();
43	}
44
45	/**
46	* Read a value.
47	*
48	* @param string $key Cache key.
49	* @param bool $use_fallback Fall back to a transient when no object cache exists.
50	* @return mixed\|false
51	*/
52	public static function get( $key, $use_fallback = true ) {
53	if ( self::is_persistent() ) {
54	$found = false;
55	$value = wp_cache_get( $key, self::GROUP, false, $found );
56	if ( $found ) {
57	return $value;
58	}
59	return false;
60	}
61
62	return $use_fallback ? get_transient( self::GROUP . '_' . $key ) : false;
63	}
64
65	/**
66	* Write a value.
67	*
68	* @param string $key Cache key.
69	* @param mixed $value Payload.
70	* @param int $ttl Lifetime in seconds.
71	* @param bool $use_fallback Fall back to a transient when no object cache exists.
72	* @return bool
73	*/
74	public static function set( $key, $value, $ttl, $use_fallback = true ) {
75	$ttl = max( 60, (int) $ttl );
76
77	if ( self::is_persistent() ) {
78	return (bool) wp_cache_set( $key, $value, self::GROUP, $ttl );
79	}
80
81	return $use_fallback ? (bool) set_transient( self::GROUP . '_' . $key, $value, $ttl ) : false;
82	}
83
84	/**
85	* Delete a value.
86	*
87	* @param string $key Cache key.
88	* @return bool
89	*/
90	public static function delete( $key ) {
91	if ( self::is_persistent() ) {
92	return (bool) wp_cache_delete( $key, self::GROUP );
93	}
94	return (bool) delete_transient( self::GROUP . '_' . $key );
95	}
96
97	/**
98	* Read a monotonic generation counter.
99	*
100	* Stored autoloaded so it costs no query on a normal page load. Bumping it
101	* invalidates every key built from it, which is one write regardless of how
102	* many entries exist and cannot half-complete the way a scan-and-delete can.
103	*
104	* @param string $option Option name.
105	* @return int
106	*/
107	public static function generation( $option ) {
108	return (int) get_option( $option, 0 );
109	}
110
111	/**
112	* Advance a generation counter.
113	*
114	* @param string $option Option name.
115	* @return void
116	*/
117	public static function bump_generation( $option ) {
118	update_option( $option, self::generation( $option ) + 1, true );
119	}
120	}
121