1: <?php
 2: 
 3: namespace malkusch\bav;
 4: 
 5: /**
 6:  * Container for DataBackend objects.
 7:  * 
 8:  * @author Markus Malkusch <markus@malkusch.de>
 9:  * @link bitcoin:1335STSwu9hST4vcMRppEPgENMHD2r1REK Donations
10:  * @license GPL
11:  * @see DataBackend
12:  * @api
13:  */
14: abstract class DataBackendContainer
15: {
16: 
17:     /**
18:      * @var string Name of the installation lock file
19:      */
20:     const INSTALL_LOCK = "bav_install.lock";
21: 
22:     /**
23:      * @var DataBackend
24:      */
25:     private $backend;
26: 
27:     /**
28:      * Returns the unconfigured backend which is only created by calling the
29:      * constructor.
30:      *
31:      * @return DataBackend
32:      */
33:     abstract protected function makeDataBackend();
34: 
35:     /**
36:      * Builds a configured data backend.
37:      *
38:      * If configured this method would automatically install the backend. I.e. a first
39:      * call will take some amount of time.
40:      * 
41:      * @return DataBackend
42:      * @throws DataBackendException
43:      */
44:     private function buildDataBackend()
45:     {
46:         $configuration = ConfigurationRegistry::getConfiguration();
47:         $backend = $this->makeDataBackend();
48: 
49:         // Installation
50:         if ($configuration->isAutomaticInstallation() && ! $backend->isInstalled()) {
51:             $lock = new Lock(self::INSTALL_LOCK);
52:             $lock->executeOnce(
53:                 function () use ($backend) {
54:                     $backend->install();
55:                 }
56:             );
57:         }
58: 
59:         // Update hook
60:         register_shutdown_function(array($this, "applyUpdatePlan"), $backend);
61: 
62:         return $backend;
63:     }
64: 
65:     /**
66:      * Shut down hook for applying the update plan.
67:      */
68:     public function applyUpdatePlan(DataBackend $backend)
69:     {
70:         $plan = ConfigurationRegistry::getConfiguration()->getUpdatePlan();
71:         if ($plan != null && $plan->isOutdated($backend)) {
72:             $plan->perform($backend);
73: 
74:         }
75:     }
76: 
77:     /**
78:      * Returns a configured data backend.
79:      *
80:      * If configured this method would automatically install and update the backend. I.e. 
81:      * some calls might take longer.
82:      *
83:      * @see Configuration::setAutomaticInstallation()
84:      * @see DataBackend::install()
85:      * @return DataBackend
86:      */
87:     public function getDataBackend()
88:     {
89:         if (is_null($this->backend)) {
90:             $this->backend = $this->buildDataBackend();
91: 
92:         }
93:         return $this->backend;
94:     }
95: }
96: