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I have placed advanced-cache.php and object-cache.php in wp-contents and updated wp-config.php with define('WP_CACHE', true);, but I do not see the messages in the page source telling me that the page is served from cache.

I have WordPress 3.8.1, APC Object Cache Backend 2.0.6, and Batcache 1.2. Once upon a time I would see the messages in the page source, but no longer. And this is across several WordPress installations. I do see the plugins showing up as installed in the Drop-ins display option under Plugins in the WordPress dashboard.

Contents of object-cache.php:

<?php
/*
Plugin Name: APC Object Cache
Description: APC backend for the WP Object Cache.
Version: 2.0.6
URI: http://txfx.net/wordpress-plugins/apc/
Author: Mark Jaquith
Author URI: http://coveredwebservices.com/

Install this file to wp-content/object-cache.php

Based on Ryan Boren's Memcached object cache backend
http://wordpress.org/extend/plugins/memcached/

*/

if ( function_exists( 'apc_fetch' ) ) :

if ( version_compare( '5.2.4', phpversion(), '>=' ) ) {
    wp_die( 'The APC object cache backend requires PHP 5.2 or higher. You are running ' . phpversion() . '. Please remove the <code>object-cache.php</code> file from your content directory.' );
}

if ( function_exists( 'wp_cache_add' ) ) {
    // Regular die, not wp_die(), because it gets sandboxed and shown in a small iframe
    die( '<strong>ERROR:</strong> This is <em>not</em> a plugin, and it should not be activated as one.<br /><br />Instead, <code>' . str_replace( $_SERVER['DOCUMENT_ROOT'], '', __FILE__ ) . '</code> must be moved to <code>' . str_replace( $_SERVER['DOCUMENT_ROOT'], '', trailingslashit( WP_CONTENT_DIR ) ) . 'object-cache.php</code>' );
} else {

// Users with setups where multiple installs share a common wp-config.php can use this
// to guarantee uniqueness for the keys generated by this object cache
if ( !defined( 'WP_APC_KEY_SALT' ) )
    define( 'WP_APC_KEY_SALT', 'wp' );

function wp_cache_add( $key, $data, $group = '', $expire = 0 ) {
    global $wp_object_cache;

    return $wp_object_cache->add( $key, $data, $group, $expire );
}

function wp_cache_incr( $key, $n = 1, $group = '' ) {
    global $wp_object_cache;

    return $wp_object_cache->incr2( $key, $n, $group );
}

function wp_cache_decr( $key, $n = 1, $group = '' ) {
    global $wp_object_cache;

    return $wp_object_cache->decr( $key, $n, $group );
}

function wp_cache_close() {
    return true;
}

function wp_cache_delete( $key, $group = '' ) {
    global $wp_object_cache;

    return $wp_object_cache->delete( $key, $group );
}

function wp_cache_flush() {
    global $wp_object_cache;

    return $wp_object_cache->flush();
}

function wp_cache_get( $key, $group = '', $force = false ) {
    global $wp_object_cache;

    return $wp_object_cache->get( $key, $group, $force );
}

function wp_cache_init() {
    global $wp_object_cache;

    $wp_object_cache = new APC_Object_Cache();
}

function wp_cache_replace( $key, $data, $group = '', $expire = 0 ) {
    global $wp_object_cache;

    return $wp_object_cache->replace( $key, $data, $group, $expire );
}

function wp_cache_set( $key, $data, $group = '', $expire = 0 ) {
    global $wp_object_cache;

    if ( defined('WP_INSTALLING') == false )
        return $wp_object_cache->set( $key, $data, $group, $expire );
    else
        return $wp_object_cache->delete( $key, $group );
}

function wp_cache_switch_to_blog( $blog_id ) {
    global $wp_object_cache;

    return $wp_object_cache->switch_to_blog( $blog_id );
}

function wp_cache_add_global_groups( $groups ) {
    global $wp_object_cache;

    $wp_object_cache->add_global_groups( $groups );
}

function wp_cache_add_non_persistent_groups( $groups ) {
    global $wp_object_cache;

    $wp_object_cache->add_non_persistent_groups( $groups );
}

class WP_Object_Cache {
    var $global_groups = array();

    var $no_mc_groups = array();

    var $cache = array();
    var $stats = array( 'get' => 0, 'delete' => 0, 'add' => 0 );
    var $group_ops = array();

    var $cache_enabled = true;
    var $default_expiration = 0;
    var $abspath = '';
    var $debug = false;

    function add( $id, $data, $group = 'default', $expire = 0 ) {
        $key = $this->key( $id, $group );

        if ( is_object( $data ) )
            $data = clone $data;

        $store_data = $data;

        if ( is_array( $data ) )
            $store_data = new ArrayObject( $data );

        if ( in_array( $group, $this->no_mc_groups ) ) {
            $this->cache[$key] = $data;
            return true;
        } elseif ( isset( $this->cache[$key] ) && $this->cache[$key] !== false ) {
            return false;
        }

        $expire = ( $expire == 0 ) ? $this->default_expiration : $expire;

        $result = apc_add( $key, $store_data, $expire );
        if ( false !== $result ) {
            @ ++$this->stats['add'];
            $this->group_ops[$group][] = "add $id";
            $this->cache[$key] = $data;
        }

        return $result;
    }

    function add_global_groups( $groups ) {
        if ( !is_array( $groups ) )
            $groups = (array) $groups;

        $this->global_groups = array_merge( $this->global_groups, $groups );
        $this->global_groups = array_unique( $this->global_groups );
    }

    function add_non_persistent_groups( $groups ) {
        if ( !is_array( $groups ) )
            $groups = (array) $groups;

        $this->no_mc_groups = array_merge( $this->no_mc_groups, $groups );
        $this->no_mc_groups = array_unique( $this->no_mc_groups );
    }

    // This is named incr2 because Batcache looks for incr
    // We will define that in a class extension if it is available (APC 3.1.1 or higher)
    function incr2( $id, $n = 1, $group = 'default' ) {
        $key = $this->key( $id, $group );
        if ( function_exists( 'apc_inc' ) )
            return apc_inc( $key, $n );
        else
            return false;
    }

    function decr( $id, $n = 1, $group = 'default' ) {
        $key = $this->key( $id, $group );
        if ( function_exists( 'apc_dec' ) )
            return apc_dec( $id, $n );
        else
            return false;
    }

    function close() {
        return true;
    }

    function delete( $id, $group = 'default' ) {
        $key = $this->key( $id, $group );

        if ( in_array( $group, $this->no_mc_groups ) ) {
            unset( $this->cache[$key] );
            return true;
        }

        $result = apc_delete( $key );

        @ ++$this->stats['delete'];
        $this->group_ops[$group][] = "delete $id";

        if ( false !== $result )
            unset( $this->cache[$key] );

        return $result;
    }

    function flush() {
        // Don't flush if multi-blog.
        if ( function_exists( 'is_site_admin' ) || defined( 'CUSTOM_USER_TABLE' ) && defined( 'CUSTOM_USER_META_TABLE' ) )
            return true;

        $this->cache = array();
        return apc_clear_cache( 'user' );
    }

    function get($id, $group = 'default', $force = false) {
        $key = $this->key($id, $group);

        if ( isset($this->cache[$key]) && ( !$force || in_array($group, $this->no_mc_groups) ) ) {
            if ( is_object( $this->cache[$key] ) )
                $value = clone $this->cache[$key];
            else
                $value = $this->cache[$key];
        } else if ( in_array($group, $this->no_mc_groups) ) {
            $this->cache[$key] = $value = false;
        } else {
            $value = apc_fetch( $key );
            if ( is_object( $value ) && 'ArrayObject' == get_class( $value ) )
                $value = $value->getArrayCopy();
            if ( NULL === $value )
                $value = false;
            $this->cache[$key] = ( is_object( $value ) ) ? clone $value : $value;
        }

        @ ++$this->stats['get'];
        $this->group_ops[$group][] = "get $id";

        if ( 'checkthedatabaseplease' === $value ) {
            unset( $this->cache[$key] );
            $value = false;
        }

        return $value;
    }

    function key( $key, $group ) {
        if ( empty( $group ) )
            $group = 'default';

        if ( false !== array_search( $group, $this->global_groups ) )
            $prefix = $this->global_prefix;
        else
            $prefix = $this->blog_prefix;

        return WP_APC_KEY_SALT . ':' . $this->abspath . ":$prefix$group:$key";
    }

    function replace( $id, $data, $group = 'default', $expire = 0 ) {
        return $this->set( $id, $data, $group, $expire );
    }

    function set( $id, $data, $group = 'default', $expire = 0 ) {
        $key = $this->key( $id, $group );
        if ( isset( $this->cache[$key] ) && ('checkthedatabaseplease' === $this->cache[$key] ) )
            return false;

        if ( is_object( $data ) )
            $data = clone $data;

        $store_data = $data;

        if ( is_array( $data ) )
            $store_data = new ArrayObject( $data );

        $this->cache[$key] = $data;

        if ( in_array( $group, $this->no_mc_groups ) )
            return true;

        $expire = ( $expire == 0 ) ? $this->default_expiration : $expire;
        $result = apc_store( $key, $store_data, $expire );

        return $result;
    }

    function switch_to_blog( $blog_id ) {
        global $table_prefix;

        $blog_id = (int) $blog_id;
        $this->blog_prefix = ( is_multisite() ? $blog_id : $table_prefix ) . ':';
    }

    function colorize_debug_line( $line ) {
        $colors = array(
            'get' => 'green',
            'set' => 'purple',
            'add' => 'blue',
            'delete' => 'red');

        $cmd = substr( $line, 0, strpos( $line, ' ' ) );

        $cmd2 = "<span style='color:{$colors[$cmd]}'>$cmd</span>";

        return $cmd2 . substr( $line, strlen( $cmd ) ) . "\n";
    }

    function stats() {
        echo "<p>\n";
        foreach ( $this->stats as $stat => $n ) {
            echo "<strong>$stat</strong> $n";
            echo "<br/>\n";
        }
        echo "</p>\n";
        echo "<h3>APC:</h3>";
        foreach ( $this->group_ops as $group => $ops ) {
            if ( !isset( $_GET['debug_queries'] ) && 500 < count( $ops ) ) {
                $ops = array_slice( $ops, 0, 500 );
                echo "<big>Too many to show! <a href='" . add_query_arg( 'debug_queries', 'true' ) . "'>Show them anyway</a>.</big>\n";
            }
            echo "<h4>$group commands</h4>";
            echo "<pre>\n";
            $lines = array();
            foreach ( $ops as $op ) {
                $lines[] = $this->colorize_debug_line($op);
            }
            print_r($lines);
            echo "</pre>\n";
        }
        if ( $this->debug ) {
            $apc_info = apc_cache_info();
            echo "<p>";
            echo "<strong>Cache Hits:</strong> {$apc_info['num_hits']}<br/>\n";
            echo "<strong>Cache Misses:</strong> {$apc_info['num_misses']}\n";
            echo "</p>\n";
        }
    }

    function WP_Object_Cache() {
        $this->abspath = md5( ABSPATH );

        global $blog_id, $table_prefix;
        $this->global_prefix = '';
        $this->blog_prefix = '';
        if ( function_exists( 'is_multisite' ) ) {
            $this->global_prefix = ( is_multisite() || defined('CUSTOM_USER_TABLE') && defined('CUSTOM_USER_META_TABLE') ) ? '' : $table_prefix;
            $this->blog_prefix = ( is_multisite() ? $blog_id : $table_prefix ) . ':';
        }

        $this->cache_hits =& $this->stats['get'];
        $this->cache_misses =& $this->stats['add'];
    }
}

if ( function_exists( 'apc_inc' ) ) {
    class APC_Object_Cache extends WP_Object_Cache {
        function incr( $id, $n = 1, $group = 'default' ) {
            return parent::incr2( $id, $n, $group );
        }
    }
} else {
    class APC_Object_Cache extends WP_Object_Cache {
        // Blank
    }
}

} // !function_exists( 'wp_cache_add' )

else : // No APC
    function apc_not_actually_running() {
        $GLOBALS['_wp_using_ext_object_cache'] = false;
        unset( $GLOBALS['wp_filter']['all'][-100]['apc_not_actually_running'] );
    }
    $GLOBALS['_wp_using_ext_object_cache'] = false; // This will get overridden as of WP 3.5, so we have to hook in to 'all':
    $GLOBALS['wp_filter']['all'][-100]['apc_not_actually_running'] = array( 'function' => 'apc_not_actually_running', 'accepted_args' => 0 );
    require_once ( ABSPATH . WPINC . '/cache.php' );
endif;

Contents of advanced-cache.php:

<?php

// nananananananananananananananana BATCACHE!!!

function batcache_cancel() {
    global $batcache;

    if ( is_object($batcache) )
        $batcache->cancel = true;
}

class batcache {
    // This is the base configuration. You can edit these variables or move them into your wp-config.php file.
    var $max_age =  300; // Expire batcache items aged this many seconds (zero to disable batcache)

    var $remote  =    0; // Zero disables sending buffers to remote datacenters (req/sec is never sent)

    var $times   =    2; // Only batcache a page after it is accessed this many times... (two or more)
    var $seconds =  120; // ...in this many seconds (zero to ignore this and use batcache immediately)

    var $group   = 'batcache'; // Name of memcached group. You can simulate a cache flush by changing this.

    var $unique  = array(); // If you conditionally serve different content, put the variable values here.

    var $headers = array(); // Add headers here. These will be sent with every response from the cache.

    var $cache_redirects = false; // Set true to enable redirect caching.
    var $redirect_status = false; // This is set to the response code during a redirect.
    var $redirect_location = false; // This is set to the redirect location.

    var $uncached_headers = array('transfer-encoding'); // These headers will never be cached. Apply strtolower.

    var $debug   = true; // Set false to hide the batcache info <!-- comment -->

    var $cache_control = true; // Set false to disable Last-Modified and Cache-Control headers

    var $cancel = false; // Change this to cancel the output buffer. Use batcache_cancel();

    var $genlock; // Used internally
    var $do; // Used internally

    function batcache( $settings ) {
        if ( is_array( $settings ) ) foreach ( $settings as $k => $v )
            $this->$k = $v;
    }

    function is_ssl() {
        if ( isset($_SERVER['HTTPS']) ) {
            if ( 'on' == strtolower($_SERVER['HTTPS']) )
                return true;
            if ( '1' == $_SERVER['HTTPS'] )
                return true;
        } elseif ( isset($_SERVER['SERVER_PORT']) && ( '443' == $_SERVER['SERVER_PORT'] ) ) {
            return true;
        }
        return false;
    }

    function status_header( $status_header ) {
        $this->status_header = $status_header;

        return $status_header;
    }

    function redirect_status( $status, $location ) {
        if ( $this->cache_redirects ) {
            $this->redirect_status = $status;
            $this->redirect_location = $location;
        }

        return $status;
    }

    function configure_groups() {
        // Configure the memcached client
        if ( ! $this->remote )
            if ( function_exists('wp_cache_add_no_remote_groups') )
                wp_cache_add_no_remote_groups(array($this->group));
        if ( function_exists('wp_cache_add_global_groups') )
            wp_cache_add_global_groups(array($this->group));
    }

    // Defined here because timer_stop() calls number_format_i18n()
    function timer_stop($display = 0, $precision = 3) {
        global $timestart, $timeend;
        $mtime = microtime();
        $mtime = explode(' ',$mtime);
        $mtime = $mtime[1] + $mtime[0];
        $timeend = $mtime;
        $timetotal = $timeend-$timestart;
        $r = number_format($timetotal, $precision);
        if ( $display )
            echo $r;
        return $r;
    }

    function ob($output) {
        if ( $this->cancel !== false )
            return $output;

        // PHP5 and objects disappearing before output buffers?
        wp_cache_init();

        // Remember, $wp_object_cache was clobbered in wp-settings.php so we have to repeat this.
        $this->configure_groups();

        // Do not batcache blank pages unless they are HTTP redirects
        $output = trim($output);
        if ( $output === '' && (!$this->redirect_status || !$this->redirect_location) )
            return;

        // Construct and save the batcache
        $cache = array(
            'output' => $output,
            'time' => time(),
            'timer' => $this->timer_stop(false, 3),
            'status_header' => $this->status_header,
            'redirect_status' => $this->redirect_status,
            'redirect_location' => $this->redirect_location,
            'version' => $this->url_version
        );

        if ( function_exists( 'headers_list' ) ) {
            foreach ( headers_list() as $header ) {
                list($k, $v) = array_map('trim', explode(':', $header, 2));
                $cache['headers'][$k] = $v;
            }
        } elseif ( function_exists( 'apache_response_headers' ) ) {
            $cache['headers'] = apache_response_headers();
        }

        if ( $cache['headers'] && !empty( $this->uncached_headers ) ) {
            foreach ( $cache['headers'] as $header => $value ) {
                if ( in_array( strtolower( $header ), $this->uncached_headers ) )
                    unset( $cache['headers'][$header] );
            }
        }

        wp_cache_set($this->key, $cache, $this->group, $this->max_age + $this->seconds + 30);

        // Unlock regeneration
        wp_cache_delete("{$this->url_key}_genlock", $this->group);

        if ( $this->cache_control ) {
            header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s', $cache['time'] ) . ' GMT', true );
            header("Cache-Control: max-age=$this->max_age, must-revalidate", false);
        }

        if ( !empty($this->headers) ) foreach ( $this->headers as $k => $v ) {
            if ( is_array( $v ) )
                header("{$v[0]}: {$v[1]}", false);
            else
                header("$k: $v", true);
        }

        // Add some debug info just before </head>
        if ( $this->debug ) {
            $tag = "<!--\n\tgenerated in " . $cache['timer'] . " seconds\n\t" . strlen(serialize($cache)) . " bytes batcached for " . $this->max_age . " seconds\n-->\n";
            if ( false !== $tag_position = strpos($output, '</head>') ) {
                $tag = "<!--\n\tgenerated in " . $cache['timer'] . " seconds\n\t" . strlen(serialize($cache)) . " bytes batcached for " . $this->max_age . " seconds\n-->\n";
                $output = substr($output, 0, $tag_position) . $tag . substr($output, $tag_position);
            }
        }

        // Pass output to next ob handler
        return $output;
    }
}
global $batcache;
// Pass in the global variable which may be an array of settings to override defaults.
$batcache = new batcache($batcache);

if ( ! defined( 'WP_CONTENT_DIR' ) )
    return;

// Never batcache interactive scripts or API endpoints.
if ( in_array(
        basename( $_SERVER['SCRIPT_FILENAME'] ),
        array(
            'wp-app.php',
            'xmlrpc.php',
            'ms-files.php',
        ) ) )
    return;

// Never batcache WP javascript generators
if ( strstr( $_SERVER['SCRIPT_FILENAME'], 'wp-includes/js' ) )
    return;

// Never batcache when POST data is present.
if ( ! empty( $GLOBALS['HTTP_RAW_POST_DATA'] ) || ! empty( $_POST ) )
    return;

// Never batcache when cookies indicate a cache-exempt visitor.
if ( is_array( $_COOKIE) && ! empty( $_COOKIE ) )
    foreach ( array_keys( $_COOKIE ) as $batcache->cookie )
        if ( $batcache->cookie != 'wordpress_test_cookie' && ( substr( $batcache->cookie, 0, 2 ) == 'wp' || substr( $batcache->cookie, 0, 9 ) == 'wordpress' || substr( $batcache->cookie, 0, 14 ) == 'comment_author' ) )
            return;

if ( ! include_once( WP_CONTENT_DIR . '/object-cache.php' ) )
    return;

wp_cache_init(); // Note: wp-settings.php calls wp_cache_init() which clobbers the object made here.

if ( ! is_object( $wp_object_cache ) )
    return;

// Now that the defaults are set, you might want to use different settings under certain conditions.

/* Example: if your documents have a mobile variant (a different document served by the same URL) you must tell batcache about the variance. Otherwise you might accidentally cache the mobile version and serve it to desktop users, or vice versa.
$batcache->unique['mobile'] = is_mobile_user_agent();
*/

/* Example: never batcache for this host
if ( $_SERVER['HTTP_HOST'] == 'do-not-batcache-me.com' )
    return;
*/

/* Example: batcache everything on this host regardless of traffic level
if ( $_SERVER['HTTP_HOST'] == 'always-batcache-me.com' ) {
    $batcache->max_age = 600; // Cache for 10 minutes
    $batcache->seconds = $batcache->times = 0; // No need to wait till n number of people have accessed the page, cache instantly
}
*/

/* Example: If you sometimes serve variants dynamically (e.g. referrer search term highlighting) you probably don't want to batcache those variants. Remember this code is run very early in wp-settings.php so plugins are not yet loaded. You will get a fatal error if you try to call an undefined function. Either include your plugin now or define a test function in this file.
if ( include_once( 'plugins/searchterm-highlighter.php') && referrer_has_search_terms() )
    return;
*/

// Disabled
if ( $batcache->max_age < 1 )
    return;

// Make sure we can increment. If not, turn off the traffic sensor.
if ( ! method_exists( $GLOBALS['wp_object_cache'], 'incr' ) )
    $batcache->times = 0;

// Necessary to prevent clients using cached version after login cookies set. If this is a problem, comment it out and remove all Last-Modified headers.
header('Vary: Cookie', false);

// Things that define a unique page.
if ( isset( $_SERVER['QUERY_STRING'] ) )
    parse_str($_SERVER['QUERY_STRING'], $batcache->query);
$batcache->keys = array(
    'host' => $_SERVER['HTTP_HOST'],
    'method' => $_SERVER['REQUEST_METHOD'],
    'path' => ( $batcache->pos = strpos($_SERVER['REQUEST_URI'], '?') ) ? substr($_SERVER['REQUEST_URI'], 0, $batcache->pos) : $_SERVER['REQUEST_URI'],
    'query' => $batcache->query,
    'extra' => $batcache->unique
);

if ( $batcache->is_ssl() )
    $batcache->keys['ssl'] = true;

$batcache->configure_groups();

// Generate the batcache key
$batcache->key = md5(serialize($batcache->keys));

// Generate the traffic threshold measurement key
$batcache->req_key = $batcache->key . '_req';

// Get the batcache
$batcache->cache = wp_cache_get($batcache->key, $batcache->group);

// Are we only caching frequently-requested pages?
if ( $batcache->seconds < 1 || $batcache->times < 2 ) {
    $batcache->do = true;
} else {
    // No batcache item found, or ready to sample traffic again at the end of the batcache life?
    if ( !is_array($batcache->cache) || time() >= $batcache->cache['time'] + $batcache->max_age - $batcache->seconds ) {
        wp_cache_add($batcache->req_key, 0, $batcache->group);
        $batcache->requests = wp_cache_incr($batcache->req_key, 1, $batcache->group);

        if ( $batcache->requests >= $batcache->times )
            $batcache->do = true;
        else
            $batcache->do = false;
    }
}

// Recreate the permalink from the URL
$batcache->permalink = 'http://' . $batcache->keys['host'] . $batcache->keys['path'] . ( isset($batcache->keys['query']['p']) ? "?p=" . $batcache->keys['query']['p'] : '' );
$batcache->url_key = md5($batcache->permalink);
$batcache->url_version = (int) wp_cache_get("{$batcache->url_key}_version", $batcache->group);

// If the document has been updated and we are the first to notice, regenerate it.
if ( $batcache->do !== false && isset($batcache->cache['version']) && $batcache->cache['version'] < $batcache->url_version )
    $batcache->genlock = wp_cache_add("{$batcache->url_key}_genlock", 1, $batcache->group);

// Did we find a batcached page that hasn't expired?
if ( isset($batcache->cache['time']) && ! $batcache->genlock && time() < $batcache->cache['time'] + $batcache->max_age ) {
    // Issue redirect if cached and enabled
    if ( $batcache->cache['redirect_status'] && $batcache->cache['redirect_location'] && $batcache->cache_redirects ) {
        $status = $batcache->cache['redirect_status'];
        $location = $batcache->cache['redirect_location'];
        // From vars.php
        $is_IIS = (strpos($_SERVER['SERVER_SOFTWARE'], 'Microsoft-IIS') !== false || strpos($_SERVER['SERVER_SOFTWARE'], 'ExpressionDevServer') !== false);
        if ( $is_IIS ) {
            header("Refresh: 0;url=$location");
        } else {
            if ( php_sapi_name() != 'cgi-fcgi' ) {
                $texts = array(
                    300 => 'Multiple Choices',
                    301 => 'Moved Permanently',
                    302 => 'Found',
                    303 => 'See Other',
                    304 => 'Not Modified',
                    305 => 'Use Proxy',
                    306 => 'Reserved',
                    307 => 'Temporary Redirect',
                );
                $protocol = $_SERVER["SERVER_PROTOCOL"];
                if ( 'HTTP/1.1' != $protocol && 'HTTP/1.0' != $protocol )
                    $protocol = 'HTTP/1.0';
                if ( isset($texts[$status]) )
                    header("$protocol $status " . $texts[$status]);
                else
                    header("$protocol 302 Found");
            }
            header("Location: $location");
        }
        exit;
    }

    // Issue "304 Not Modified" only if the dates match exactly.
    if ( $batcache->cache_control && isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ) {
        $since = strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE']);
        if ( isset($batcache->cache['headers']['Last-Modified']) )
            $batcache->cache['time'] = strtotime( $batcache->cache['headers']['Last-Modified'] );
        if ( $batcache->cache['time'] == $since ) {
            header('Last-Modified: ' . $_SERVER['HTTP_IF_MODIFIED_SINCE'], true, 304);
            exit;
        }
    }

    // Use the batcache save time for Last-Modified so we can issue "304 Not Modified"
    if ( $batcache->cache_control ) {
        header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s', $batcache->cache['time'] ) . ' GMT', true );
        header('Cache-Control: max-age=' . ($batcache->max_age - time() + $batcache->cache['time']) . ', must-revalidate', true);
    }

    // Add some debug info just before </head>
    if ( $batcache->debug ) {
        if ( false !== $tag_position = strpos($batcache->cache['output'], '</head>') ) {
            $tag = "<!--\n\tgenerated " . (time() - $batcache->cache['time']) . " seconds ago\n\tgenerated in " . $batcache->cache['timer'] . " seconds\n\tserved from batcache in " . $batcache->timer_stop(false, 3) . " seconds\n\texpires in " . ($batcache->max_age - time() + $batcache->cache['time']) . " seconds\n-->\n";
            $batcache->cache['output'] = substr($batcache->cache['output'], 0, $tag_position) . $tag . substr($batcache->cache['output'], $tag_position);
        }
    }

    if ( !empty($batcache->cache['headers']) ) foreach ( $batcache->cache['headers'] as $k => $v )
        header("$k: $v", true);

    if ( !empty($batcache->headers) ) foreach ( $batcache->headers as $k => $v ) {
        if ( is_array( $v ) )
            header("{$v[0]}: {$v[1]}", false);
        else
            header("$k: $v", true);
    }

    if ( !empty($batcache->cache['status_header']) )
        header($batcache->cache['status_header'], true);

    // Have you ever heard a death rattle before?
    die($batcache->cache['output']);
}

// Didn't meet the minimum condition?
if ( !$batcache->do && !$batcache->genlock )
    return;

$wp_filter['status_header'][10]['batcache'] = array( 'function' => array(&$batcache, 'status_header'), 'accepted_args' => 1 );
$wp_filter['wp_redirect_status'][10]['batcache'] = array( 'function' => array(&$batcache, 'redirect_status'), 'accepted_args' => 2 );

ob_start(array(&$batcache, 'ob'));

// It is safer to omit the final PHP closing tag.
3
  • Note that unlike other full page caching plugins Batcache is typically configured to only cache pages when they have been hit several times in time period. Are you sure you are checking such pages for messages? In other words try to F5 several times first. :)
    – Rarst
    Commented Feb 8, 2014 at 22:05
  • @Rarst Yes, I refreshed several times before looking at page source. I have previously had the plugin working and displaying the message. See my "solution" in the answer below, lulz.
    – Paul
    Commented Feb 8, 2014 at 22:16
  • 1
    We (the moderators team) have just discussed this issue and decided to reopen this question. It might be a simple solution, but it might be needed from time to time as it's a common misunderstanding. The other reason was that it includes all the code, which might as well be interesting for later visitors.
    – kaiser
    Commented Feb 9, 2014 at 0:05

1 Answer 1

0

Sigh. Ever humbling servers and sites are. The problem was with being logged in - the cache message shows up when using a browser where I'm not logged in. "Problem" solved.

1
  • 1
    Sidenote: Else you'd cache error messages for admins as well ;)
    – kaiser
    Commented Feb 8, 2014 at 23:51

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