$string['pluginname'] = 'File cache';
$string['prescan'] = 'Prescan directory';
$string['prescan_help'] = 'If enabled the directory is scanned when the cache is first used and requests for files are first checked against the scan data. This can help if you have a slow file system and are finding that file operations are causing you a bottle neck.';
+$string['singledirectory'] = 'Single directory store';
+$string['singledirectory_help'] = 'If enabled files (cached items) will be stored in a single directory rather than being broken up into multiple directories.<br />
+Enabling this will speed up file interactions but comes at the cost of increased risk of hitting file system limitations.<br />
+It is advisable to only turn this on if the following is true:<br />
+ - If you know the number of items in the cache is going to be small enough that it won\'t cause issues on the file system you are running with.<br />
+ - The data being cached is not expensive to generate. If it is then sticking with the default may still be the better option as it reduces the chance of issues.';
+
+/**
+ * This is is like the file store, but designed for siutations where:
+ * - many more things are likely to be stored in the cache, so CRC hashing is
+ * too likely to give collisions, and storing everything in a completely flat
+ * directory structure is inadvisable.
+ * - the things we are caching are more expensive to calculate, so the extra
+ * time to computer a better hash is a worthwhile trade-off.
+ */
\ No newline at end of file
*/
protected $prescan = false;
+ /**
+ * Set to true if we should store files within a single directory.
+ * By default we use a nested structure in order to reduce the chance of conflicts and avoid any file system
+ * limitations such as maximum files per directory.
+ * @var bool
+ */
+ protected $singledirectory = false;
+
/**
* Set to true when the path should be automatically created if it does not yet exist.
* @var bool
}
$this->isready = $path !== false;
$this->path = $path;
- $this->prescan = array_key_exists('prescan', $configuration) ? (bool)$configuration['prescan'] : false;
+ // Check if we should prescan the directory.
+ if (array_key_exists('prescan', $configuration)) {
+ $this->prescan = (bool)$configuration['prescan'];
+ } else {
+ // Default is no, we should not prescan.
+ $this->prescan = false;
+ }
+ // Check if we should be storing in a single directory.
+ if (array_key_exists('singledirectory', $configuration)) {
+ $this->singledirectory = (bool)$configuration['singledirectory'];
+ } else {
+ // Default: No, we will use multiple directories.
+ $this->singledirectory = false;
+ }
}
/**
$this->prescan = false;
}
if ($this->prescan) {
- $pattern = $this->path.'/*.cache';
- foreach (glob($pattern, GLOB_MARK | GLOB_NOSORT) as $filename) {
- $this->keys[basename($filename)] = filemtime($filename);
+ $this->prescan_keys();
+ }
+ }
+
+ /**
+ * Pre-scan the cache to see which keys are present.
+ */
+ protected function prescan_keys() {
+ foreach (glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT) as $filename) {
+ $this->keys[basename($filename)] = filemtime($filename);
+ }
+ }
+
+ /**
+ * Gets a pattern suitable for use with glob to find all keys in the cache.
+ * @return string The pattern.
+ */
+ protected function glob_keys_pattern() {
+ if ($this->singledirectory) {
+ return $this->path . '/*.cache';
+ } else {
+ return $this->path . '/*/*/*.cache';
+ }
+ }
+
+ /**
+ * Returns the file path to use for the given key.
+ *
+ * @param string $key The key to generate a file path for.
+ * @param bool $create If set to the true the directory structure the key requires will be created.
+ * @return string The full path to the file that stores a particular cache key.
+ */
+ protected function file_path_for_key($key, $create = false) {
+ if ($this->singledirectory) {
+ // Its a single directory, easy, just the store instances path + the file name.
+ return $this->path . '/' . $key . '.cache';
+ } else {
+ // We are using multiple subdirectories. We want two levels.
+ $subdir1 = substr($key, 0, 2);
+ $subdir2 = substr($key, 2, 2);
+ $dir = $this->path . '/' . $subdir1 .'/'. $subdir2;
+ if ($create) {
+ // Create the directory. This function does it recursivily!
+ make_writable_directory($dir);
}
+ return $dir . '/' . $key . '.cache';
}
}
*/
public function get($key) {
$filename = $key.'.cache';
- $file = $this->path.'/'.$filename;
+ $file = $this->file_path_for_key($key);
$ttl = $this->definition->get_ttl();
if ($ttl) {
$maxtime = cache::now() - $ttl;
*/
public function delete($key) {
$filename = $key.'.cache';
- $file = $this->path.'/'.$filename;
+ $file = $this->file_path_for_key($key);
$result = @unlink($file);
unset($this->keys[$filename]);
return $result;
public function set($key, $data) {
$this->ensure_path_exists();
$filename = $key.'.cache';
- $file = $this->path.'/'.$filename;
+ $file = $this->file_path_for_key($key, true);
$result = $this->write_file($file, $this->prep_data_before_save($data));
if (!$result) {
// Couldn't write the file.
*/
public function has($key) {
$filename = $key.'.cache';
- $file = $this->path.'/'.$key.'.cache';
$maxtime = cache::now() - $this->definition->get_ttl();
if ($this->prescan) {
return array_key_exists($filename, $this->keys) && $this->keys[$filename] >= $maxtime;
}
+ $file = $this->file_path_for_key($key);
return (file_exists($file) && ($this->definition->get_ttl() == 0 || filemtime($file) >= $maxtime));
}
* @return boolean True on success. False otherwise.
*/
public function purge() {
- $pattern = $this->path.'/*.cache';
- foreach (glob($pattern, GLOB_MARK | GLOB_NOSORT) as $filename) {
+ foreach (glob($this->glob_keys_pattern(), GLOB_MARK | GLOB_NOSORT) as $filename) {
@unlink($filename);
}
$this->keys = array();
