wp_cache_init(): void

// Typically called internally during load
wp_cache_init();

// After init, global is available
global $wp_object_cache;

wp_cache_get(
    int|string $key,
    string $group = '',
    bool $force = false,
    bool &$found = null
): mixed|false

// Simple get
$value = wp_cache_get( 'my_key', 'my_group' );

// Distinguish false value from cache miss
$value = wp_cache_get( 'key', 'group', false, $found );
if ( ! $found ) {
    // Key doesn't exist in cache
    $value = compute_value();
    wp_cache_set( 'key', $value, 'group' );
}

wp_cache_set(
    int|string $key,
    mixed $data,
    string $group = '',
    int $expire = 0
): bool

// Cache for 1 hour
wp_cache_set( 'user_stats', $stats, 'my_plugin', HOUR_IN_SECONDS );

// No expiration (lives until flush or request ends)
wp_cache_set( 'config', $config, 'settings' );

wp_cache_add(
    int|string $key,
    mixed $data,
    string $group = '',
    int $expire = 0
): bool

// Only set if not present
$added = wp_cache_add( 'lock', time(), 'my_plugin' );
if ( ! $added ) {
    // Another process already has the lock
}

wp_cache_replace(
    int|string $key,
    mixed $data,
    string $group = '',
    int $expire = 0
): bool

// Update only if exists
$replaced = wp_cache_replace( 'session_data', $new_data, 'sessions' );
if ( ! $replaced ) {
    // Session doesn't exist yet
    wp_cache_add( 'session_data', $new_data, 'sessions' );
}

wp_cache_delete(
    int|string $key,
    string $group = ''
): bool

// Delete specific entry
wp_cache_delete( 'user_123', 'user_data' );

// After updating post, invalidate cache
wp_cache_delete( $post_id, 'posts' );

wp_cache_get_multiple(
    array $keys,
    string $group = '',
    bool $force = false
): array

$post_ids = array( 1, 2, 3, 4, 5 );
$posts = wp_cache_get_multiple( $post_ids, 'posts' );

foreach ( $posts as $id => $post ) {
    if ( false === $post ) {
        // Not in cache, need to fetch
    }
}

wp_cache_set_multiple(
    array $data,
    string $group = '',
    int $expire = 0
): bool[]

$data = array(
    'post_1' => $post1,
    'post_2' => $post2,
    'post_3' => $post3,
);
$results = wp_cache_set_multiple( $data, 'posts', HOUR_IN_SECONDS );

wp_cache_add_multiple(
    array $data,
    string $group = '',
    int $expire = 0
): bool[]

wp_cache_delete_multiple(
    array $keys,
    string $group = ''
): bool[]

$keys = array( 'item_1', 'item_2', 'item_3' );
wp_cache_delete_multiple( $keys, 'my_group' );

wp_cache_incr(
    int|string $key,
    int $offset = 1,
    string $group = ''
): int|false

// Initialize counter
wp_cache_set( 'page_views', 0, 'stats' );

// Increment
$new_count = wp_cache_incr( 'page_views', 1, 'stats' ); // Returns 1
$new_count = wp_cache_incr( 'page_views', 5, 'stats' ); // Returns 6

wp_cache_decr(
    int|string $key,
    int $offset = 1,
    string $group = ''
): int|false

wp_cache_set( 'stock', 10, 'inventory' );

$remaining = wp_cache_decr( 'stock', 1, 'inventory' ); // Returns 9
$remaining = wp_cache_decr( 'stock', 20, 'inventory' ); // Returns 0 (not -11)

wp_cache_flush(): bool

// Clear everything (use sparingly!)
wp_cache_flush();

wp_cache_flush_runtime(): bool

// In a CLI command processing many items
foreach ( $large_dataset as $item ) {
    process( $item );
    
    // Periodically clear memory
    if ( $i % 1000 === 0 ) {
        wp_cache_flush_runtime();
    }
}

wp_cache_flush_group( string $group ): bool

// Check support first
if ( wp_cache_supports( 'flush_group' ) ) {
    wp_cache_flush_group( 'my_plugin' );
}

wp_cache_add_global_groups( string|string[] $groups ): void

// In sunrise.php or object-cache.php
wp_cache_add_global_groups( array(
    'users',
    'userlogins', 
    'usermeta',
    'site-transient',
    'my_plugin_global',
) );

wp_cache_add_non_persistent_groups( string|string[] $groups ): void

// Request-specific data that shouldn't persist
wp_cache_add_non_persistent_groups( array(
    'counts',
    'request_data',
    'temporary',
) );

wp_cache_switch_to_blog( int $blog_id ): void

// Cache for current site
wp_cache_set( 'option', $value, 'options' ); // Key: 1:option (on site 1)

// Switch context
wp_cache_switch_to_blog( 2 );
wp_cache_set( 'option', $other_value, 'options' ); // Key: 2:option

wp_cache_reset(): void

wp_cache_supports( string $feature ): bool

if ( wp_cache_supports( 'get_multiple' ) ) {
    $results = wp_cache_get_multiple( $keys, 'group' );
} else {
    $results = array();
    foreach ( $keys as $key ) {
        $results[ $key ] = wp_cache_get( $key, 'group' );
    }
}

wp_cache_close(): true

wp_cache_get_salted(
    string $cache_key,
    string $group,
    string|string[] $salt
): mixed|false

$salt = get_option( 'posts_last_modified' );
$data = wp_cache_get_salted( 'all_posts', 'my_plugin', $salt );

if ( false === $data ) {
    $data = expensive_query();
    wp_cache_set_salted( 'all_posts', $data, 'my_plugin', $salt );
}

wp_cache_set_salted(
    string $cache_key,
    mixed $data,
    string $group,
    string|string[] $salt,
    int $expire = 0
): bool

wp_cache_get_multiple_salted(
    array $cache_keys,
    string $group,
    string|string[] $salt
): array

wp_cache_set_multiple_salted(
    array $data,
    string $group,
    string|string[] $salt,
    int $expire = 0
): bool[]