Stop Nuclear Cache Purge

Resolved G
(@gnetworkau)

5 years, 2 months ago

Hi Donncha and all, I’ve been using Supercache for years now as it seems the best available cache plugin for WordPress. I did at sometime use mod_cache and have gone back to it for now, but it has its own problems. I would prefer to keep using Supercache – its closely integrated to both WP and Apache – but it has a long standing problem which finally got to me, hence today’s post.

The Problem: Nuclear Cache Purge (I call it), where it purges the entire cache on Multisite, when not warranted.
I use the plugin Tablepress, and whenever I update a table, the entire cache gets purged. At all other times everything works perfectly, if I update a page/post only that page is refreshed, so all good.
I think Tablepress may post as a custom post type, but I read in the supercache development posts that custom post type issues had been resolved…?

My settings include:
Expert Mode (yes all htaccess rules used are good)
Refresh pages only when comment is made

I would like to see an option of No Purge at all, unless by page hard reload.

Any ideas?

Viewing 6 replies - 1 through 6 (of 6 total)

Thread Starter G
(@gnetworkau)

5 years, 2 months ago

I have just come back to using Supercache, as mod_cache was too problematic. Supercache works perfectly except for that one small problem. I investigate further, and still open to suggestions…

These are all my active settings:

EXPERT Mode
Don’t cache pages for known users. (Recommended)
Don’t cache pages with GET parameters. (?x=y at the end of a url)
Compress pages so they’re served more quickly to visitors. (Recommended)
Cache rebuild. Serve a supercache file to anonymous users while a new file is being generated. (Recommended)
Only refresh current page when comments made.
Thread Starter G
(@gnetworkau)

5 years, 2 months ago
I solved it myself, by disabling the offending code. This is how…

In the file wp-cache-phase2.php comment out the 2 lines in this section:
```
/* Clear out the cache directory. */
...
//	prune_super_cache( $cache_path . 'supercache/', true );
//	prune_super_cache( $cache_path, true );
```
No more nuclear purges – sweeeet!
Saša
(@stodorovic)

5 years, 2 months ago
It seems that you changed the code in function wp_cache_clear_cache. This function is using only from hook wp_update_nav_menu and I’ve tried to search codebase in TablePress (I’ve found method _flush_caching_plugins_caches in models/model-table.php):
```
/**
 * Flush the caches of the plugins W3 Total Cache, WP Super Cache, Cachify, and Quick Cache.
 *
 * @since 1.0.0
 */
public function _flush_caching_plugins_caches() {
	/**
	 * Filter whether the caches of common caching plugins shall be flushed.
	 *
	 * @since 1.0.0
	 *
	 * @param bool $flush Whether caches of caching plugins shall be flushed. Default true.
	 */
	if ( ! apply_filters( 'tablepress_flush_caching_plugins_caches', true ) ) {
		return;
	}

	// W3 Total Cache
	if ( function_exists( 'w3tc_pgcache_flush' ) ) {
		w3tc_pgcache_flush();
	}
	// WP Super Cache
	if ( function_exists( 'wp_cache_clear_cache' ) ) {
		wp_cache_clear_cache();
	}
```
It’s an issue in TablePress because it isn’t good approach for multisite installation. We could create an issue on TablePress forum.

Also, you can use filter tablepress_flush_caching_plugins_caches to prevent running of this code. I think that following code should work (and you don’t need to change code in WPSC):
```
add_filter( 'tablepress_flush_caching_plugins_caches', '__return_false' );
```
Thread Starter G
(@gnetworkau)

5 years, 2 months ago
@stodorovic thanks for that – it works!

It already was discussed in Tablepress forum.

I would have liked to stop the purge from the Supercache side, as any rogue plugin could initiate a purge in future. I prefer that the cache is NEVER purged; if there is a major upgrade, I can press “Delete Cache on all blogs” or clear by ftp.

I tried the following but it did not work:
```
global $cache_path;
remove_filter( 'wp_update_nav_menu', array($cache_path, 'wp_cache_clear_cache') );
```
Ok for now…
Saša
(@stodorovic)

5 years, 2 months ago
I think that remove_action should be called later and function wp_cache_clear_cache_on_menu isn’t method in any class (you don’t need to pass any instance). You can try this:
```
add_action( 'init', function() {
	remove_action( 'wp_update_nav_menu', 'wp_cache_clear_cache_on_menu' );
}, 20 );
```
I didn’t tested (but I’m pretty sure that will be called after add_action).
Thread Starter G
(@gnetworkau)

5 years, 2 months ago

I tried this, but Tablepress blew it away.
If you know of any function that can totally disable full cache purge, I would like to know, but I don’t really need it right now, as the filter to tablepress is doing the job. Thanks.

Viewing 6 replies - 1 through 6 (of 6 total)

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