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<?php |
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/* |
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* Copyright 2010 Google Inc. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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|
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/** |
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* A persistent storage class based on the APC cache, which is not |
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* really very persistent, as soon as you restart your web server |
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* the storage will be wiped, however for debugging and/or speed |
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* it can be useful, kinda, and cache is a lot cheaper then storage. |
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* |
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* @author Chris Chabot <chabotc@google.com> |
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*/ |
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class apiApcCache extends apiCache { |
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|
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public function __construct() { |
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if (! function_exists('apc_add')) { |
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throw new apiCacheException("Apc functions not available"); |
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} |
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} |
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|
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private function isLocked($key) { |
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if ((@apc_fetch($key . '.lock')) === false) { |
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return false; |
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} |
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return true; |
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} |
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|
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private function createLock($key) { |
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// the interesting thing is that this could fail if the lock was created in the meantime.. |
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// but we'll ignore that out of convenience |
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@apc_add($key . '.lock', '', 5); |
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} |
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|
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private function removeLock($key) { |
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// suppress all warnings, if some other process removed it that's ok too |
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@apc_delete($key . '.lock'); |
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} |
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|
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private function waitForLock($key) { |
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// 20 x 250 = 5 seconds |
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$tries = 20; |
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$cnt = 0; |
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do { |
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// 250 ms is a long time to sleep, but it does stop the server from burning all resources on polling locks.. |
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usleep(250); |
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$cnt ++; |
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} while ($cnt <= $tries && $this->isLocked($key)); |
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if ($this->isLocked($key)) { |
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// 5 seconds passed, assume the owning process died off and remove it |
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$this->removeLock($key); |
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} |
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} |
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|
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/** |
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* @inheritDoc |
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*/ |
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public function get($key, $expiration = false) { |
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|
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if (($ret = @apc_fetch($key)) === false) { |
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return false; |
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} |
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if (!$expiration || (time() - $ret['time'] > $expiration)) { |
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$this->delete($key); |
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return false; |
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} |
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return unserialize($ret['data']); |
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} |
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|
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/** |
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* @inheritDoc |
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*/ |
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public function set($key, $value) { |
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if (@apc_store($key, array('time' => time(), 'data' => serialize($value))) == false) { |
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throw new apiCacheException("Couldn't store data"); |
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} |
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} |
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|
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/** |
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* @inheritDoc |
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*/ |
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public function delete($key) { |
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@apc_delete($key); |
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} |
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} |
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|
