Viewing file:  SysvConfigStorage.php (4.61 KB) -rw-r--r--
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<?php
/**
* Copyright 2017 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace Google\Cloud\Core\Batch;
/**
* ConfigStorageInterface implementation with SystemV IPC shared memory.
*
* @experimental The experimental flag means that while we believe this method
* or class is ready for use, it may change before release in backwards-
* incompatible ways. Please use with caution, and test thoroughly when
* upgrading.
*/
class SysvConfigStorage implements ConfigStorageInterface
{
const VAR_KEY = 1;
const DEFAULT_SHM_SIZE = 200000;
const DEFAULT_PERM = 0600;
const DEFAULT_PROJECT = 'A';
/* @var int */
private $sysvKey;
/* @var int */
private $semid;
/* @var int */
private $shmSize;
/* @var int */
private $perm;
/* @var string */
private $project;
/**
* Prepare the key for semaphore and shared memory.
*/
public function __construct()
{
$this->shmSize = intval(getenv('GOOGLE_CLOUD_BATCH_SHM_SIZE'));
if ($this->shmSize === 0) {
$this->shmSize = self::DEFAULT_SHM_SIZE;
}
$this->perm = octdec(getenv('GOOGLE_CLOUD_BATCH_PERM'));
if ($this->perm === 0) {
$this->perm = self::DEFAULT_PERM;
}
$this->project = getenv('GOOGLE_CLOUD_BATCH_PROJECT');
if ($this->project === false) {
$this->project = self::DEFAULT_PROJECT;
}
$this->sysvKey = ftok(__FILE__, $this->project);
$this->semid = sem_get($this->sysvKey, 1, $this->perm, 1);
}
/**
* Acquire a lock.
*
* @return bool
*/
public function lock()
{
return sem_acquire($this->semid);
}
/**
* Release a lock.
*
* @return bool
*/
public function unlock()
{
return sem_release($this->semid);
}
/**
* Save the given JobConfig.
*
* @param JobConfig $config A JobConfig to save.
* @return bool
* @throws \RuntimeException when failed to attach to the shared memory or serialization fails
*/
public function save(JobConfig $config)
{
$shmid = shm_attach($this->sysvKey, $this->shmSize, $this->perm);
if ($shmid === false) {
throw new \RuntimeException(
'Failed to attach to the shared memory'
);
}
// If the variable write fails, clear the memory and re-raise the exception
try {
$result = shm_put_var($shmid, self::VAR_KEY, $config);
} catch (\Exception $e) {
$this->clear();
throw new \RuntimeException($e->getMessage());
} finally {
shm_detach($shmid);
}
return $result;
}
/**
* Load a JobConfig from the storage.
*
* @return JobConfig
* @throws \RuntimeException when failed to attach to the shared memory or deserialization fails
*/
public function load()
{
$shmid = shm_attach($this->sysvKey, $this->shmSize, $this->perm);
if ($shmid === false) {
throw new \RuntimeException(
'Failed to attach to the shared memory'
);
}
if (! shm_has_var($shmid, self::VAR_KEY)) {
$result = new JobConfig();
} else {
$result = shm_get_var($shmid, self::VAR_KEY);
}
shm_detach($shmid);
if ($result === false) {
throw new \RuntimeException(
'Failed to deserialize data from shared memory'
);
}
return $result;
}
/**
* Clear the JobConfig from storage.
*/
public function clear()
{
$shmid = shm_attach($this->sysvKey, $this->shmSize, $this->perm);
shm_remove_var($shmid, self::VAR_KEY);
}
/**
* Serialize the object
*/
public function __serialize()
{
$vars = get_object_vars($this);
// As of PHP 8.0, "semid" is the unserializable object "SysvSemaphore"
// @see https://github.com/googleapis/google-cloud-php/issues/3749
unset($vars['semid']);
return $vars;
}
}
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