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<?php |
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namespace Fwlib\Db; |
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/** |
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* Sequences of number management |
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* |
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* Design for profile unique code generate. Use prefix to identify different |
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* profile, or profile in different category. |
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* |
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* Should use db transaction for concurrence, or similar mechanism for non-db |
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* storage. Even though this class may not suitable for high concurrence |
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* system, which should use native db sequence/identity or better others. |
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* |
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* @copyright Copyright 2014-2015 Fwolf |
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* @license http://www.gnu.org/licenses/lgpl.html LGPL-3.0+ |
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*/ |
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abstract class AbstractSequence |
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{ |
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/** |
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* Get a number and prepare next |
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* |
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* @param string $prefix |
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* @param integer $step |
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* @return integer |
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*/ |
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public function get($prefix, $step = 1) |
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{ |
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$this->lockStorage($prefix); |
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$current = $this->read($prefix); |
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if (is_null($current)) { |
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$current = $this->getStartNumber($prefix); |
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$this->initialize($prefix, $current + $step); |
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} else { |
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$this->increase($prefix, $step); |
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} |
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$this->unlockStorage($prefix); |
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return $current; |
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} |
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/** |
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* Get start number of prefix |
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* |
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* In common the value will be 1, but sometimes we need extend and rewrite |
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* this method in child class, to get start number from exists used code. |
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* |
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* @param string $prefix |
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* @return integer |
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*/ |
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protected function getStartNumber($prefix) |
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{ |
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return 1; |
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} |
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/** |
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* Increase value of a prefix |
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* |
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* @param string $prefix |
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* @param integer $step |
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*/ |
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abstract protected function increase($prefix, $step); |
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/** |
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* Create new record in storage for prefix and set value |
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* |
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* @param string $prefix |
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* @param integer $value |
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*/ |
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abstract protected function initialize($prefix, $value); |
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/** |
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* Lock storage, prohibit others to read/write |
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* |
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* @param string $prefix |
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*/ |
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abstract protected function lockStorage($prefix); |
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/** |
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* Read current value of prefix from storage |
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* |
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* Return null if current prefix has no corresponding value. |
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* |
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* @param string $prefix |
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* @return integer|null |
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*/ |
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abstract protected function read($prefix); |
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/** |
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* Unlock storage, allow others to read/write |
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* |
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* @param string $prefix |
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*/ |
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abstract protected function unlockStorage($prefix); |
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} |
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fwolf /
fwlib
This check looks from parameters that have been defined for a function or method, but which are not used in the method body.