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PhutilDirectoryKeyValueCache.php
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Wed, Dec 18, 06:26

PhutilDirectoryKeyValueCache.php
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<?php
/**
* Interface to a directory-based disk cache. Storage persists across requests.
*
* This cache is very very slow, and most suitable for command line scripts
* which need to build large caches derived from sources like working copies
* (for example, Diviner). This cache performs better for large amounts of
* data than @{class:PhutilOnDiskKeyValueCache} because each key is serialized
* individually, but this comes at the cost of having even slower reads and
* writes.
*
* In addition to having slow reads and writes, this entire cache locks for
* any read or write activity.
*
* Keys for this cache treat the character "/" specially, and encode it as
* a new directory on disk. This can help keep the cache organized and keep the
* number of items in any single directory under control, by using keys like
* "ab/cd/efghijklmn".
*
* @task kvimpl Key-Value Cache Implementation
* @task storage Cache Storage
*/
final class PhutilDirectoryKeyValueCache extends PhutilKeyValueCache {
private $lock;
private $cacheDirectory;
/* -( Key-Value Cache Implementation )------------------------------------- */
public function isAvailable() {
return true;
}
public function getKeys(array $keys) {
$this->validateKeys($keys);
try {
$this->lockCache();
} catch (PhutilLockException $ex) {
return array();
}
$now = time();
$results = array();
foreach ($keys as $key) {
$key_file = $this->getKeyFile($key);
try {
$data = Filesystem::readFile($key_file);
} catch (FilesystemException $ex) {
continue;
}
$data = unserialize($data);
if (!$data) {
continue;
}
if (isset($data['ttl']) && $data['ttl'] < $now) {
continue;
}
$results[$key] = $data['value'];
}
$this->unlockCache();
return $results;
}
public function setKeys(array $keys, $ttl = null) {
$this->validateKeys(array_keys($keys));
$this->lockCache(15);
if ($ttl) {
$ttl_epoch = time() + $ttl;
} else {
$ttl_epoch = null;
}
foreach ($keys as $key => $value) {
$dict = array(
'value' => $value,
);
if ($ttl_epoch) {
$dict['ttl'] = $ttl_epoch;
}
try {
$key_file = $this->getKeyFile($key);
$key_dir = dirname($key_file);
if (!Filesystem::pathExists($key_dir)) {
Filesystem::createDirectory(
$key_dir,
$mask = 0755,
$recursive = true);
}
$new_file = $key_file.'.new';
Filesystem::writeFile($new_file, serialize($dict));
Filesystem::rename($new_file, $key_file);
} catch (FilesystemException $ex) {
phlog($ex);
}
}
$this->unlockCache();
return $this;
}
public function deleteKeys(array $keys) {
$this->validateKeys($keys);
$this->lockCache(15);
foreach ($keys as $key) {
$path = $this->getKeyFile($key);
Filesystem::remove($path);
// If removing this key leaves the directory empty, clean it up. Then
// clean up any empty parent directories.
$path = dirname($path);
do {
if (!Filesystem::isDescendant($path, $this->getCacheDirectory())) {
break;
}
if (Filesystem::listDirectory($path, true)) {
break;
}
Filesystem::remove($path);
$path = dirname($path);
} while (true);
}
$this->unlockCache();
return $this;
}
public function destroyCache() {
Filesystem::remove($this->getCacheDirectory());
return $this;
}
/* -( Cache Storage )------------------------------------------------------ */
/**
* @task storage
*/
public function setCacheDirectory($directory) {
$this->cacheDirectory = rtrim($directory, '/').'/';
return $this;
}
/**
* @task storage
*/
private function getCacheDirectory() {
if (!$this->cacheDirectory) {
throw new Exception(
pht(
'Call %s before using a directory cache!',
'setCacheDirectory()'));
}
return $this->cacheDirectory;
}
/**
* @task storage
*/
private function getKeyFile($key) {
// Colon is a drive separator on Windows.
$key = str_replace(':', '_', $key);
// NOTE: We add ".cache" to each file so we don't get a collision if you
// set the keys "a" and "a/b". Without ".cache", the file "a" would need
// to be both a file and a directory.
return $this->getCacheDirectory().$key.'.cache';
}
/**
* @task storage
*/
private function validateKeys(array $keys) {
foreach ($keys as $key) {
// NOTE: Use of "." is reserved for ".lock", "key.new" and "key.cache".
// Use of "_" is reserved for converting ":".
if (!preg_match('@^[a-zA-Z0-9/:-]+$@', $key)) {
throw new Exception(
pht(
"Invalid key '%s': directory caches may only contain letters, ".
"numbers, hyphen, colon and slash.",
$key));
}
}
}
/**
* @task storage
*/
private function lockCache($wait = 0) {
if ($this->lock) {
throw new Exception(
pht(
'Trying to %s with a lock!',
__FUNCTION__.'()'));
}
if (!Filesystem::pathExists($this->getCacheDirectory())) {
Filesystem::createDirectory($this->getCacheDirectory(), 0755, true);
}
$lock = PhutilFileLock::newForPath($this->getCacheDirectory().'.lock');
$lock->lock($wait);
$this->lock = $lock;
}
/**
* @task storage
*/
private function unlockCache() {
if (!$this->lock) {
throw new Exception(
pht(
'Call %s before %s!',
'lockCache()',
__FUNCTION__.'()'));
}
$this->lock->unlock();
$this->lock = null;
}
}

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