LaravelFreelancerNL /
laravel-arangodb
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| 1 | <?php |
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| 2 | |||
| 3 | namespace LaravelFreelancerNL\Aranguent\Concerns; |
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| 4 | |||
| 5 | use ArangoDBClient\Transaction as ArangoTransaction; |
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| 6 | use Closure; |
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| 7 | use Exception; |
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| 8 | use Illuminate\Support\Fluent as IlluminateFluent; |
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| 9 | |||
| 10 | trait ManagesTransactions |
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| 11 | { |
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| 12 | protected $transactions = 0; |
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| 13 | |||
| 14 | protected $transactionCommands = []; |
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| 15 | |||
| 16 | protected $arangoTransaction; |
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| 17 | |||
| 18 | /** |
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| 19 | * Execute a Closure within a transaction. |
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| 20 | * |
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| 21 | * @param \Closure $callback |
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| 22 | * @param array $options |
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| 23 | * @param int $attempts |
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| 24 | * @return mixed |
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| 25 | * |
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| 26 | * @throws \Exception|\Throwable |
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| 27 | */ |
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| 28 | public function transaction(Closure $callback, $options = [], $attempts = 1) |
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| 29 | { |
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| 30 | $this->beginTransaction(); |
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| 31 | |||
| 32 | return tap($callback($this), function () use ($options, $attempts) { |
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| 33 | $this->commit($options, $attempts); |
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| 34 | }); |
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| 35 | } |
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| 36 | |||
| 37 | /** |
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| 38 | * Start a new database transaction. |
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| 39 | * |
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| 40 | * @return void |
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| 41 | * |
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| 42 | * @throws \Exception |
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| 43 | */ |
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| 44 | public function beginTransaction() |
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| 45 | { |
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| 46 | $this->transactions++; |
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| 47 | |||
| 48 | $this->transactionCommands[$this->transactions] = []; |
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| 49 | |||
| 50 | $this->fireConnectionEvent('beganTransaction'); |
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| 51 | } |
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| 52 | |||
| 53 | /** |
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| 54 | * Add a command to the transaction. Parameters must include: |
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| 55 | * collections['write'][]: collections that are written to |
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| 56 | * collections['read'][]: collections that are read from |
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| 57 | * command: the db command to execute. |
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| 58 | * |
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| 59 | * @param \Illuminate\Support\Fluent $command |
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| 60 | */ |
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| 61 | public function addTransactionCommand(IlluminateFluent $command) |
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| 62 | { |
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| 63 | $this->transactionCommands[$this->transactions][] = $command; |
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| 64 | } |
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| 65 | |||
| 66 | /** |
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| 67 | * Add a query command to the transaction. |
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| 68 | * |
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| 69 | * @param $query |
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| 70 | * @param $bindings |
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| 71 | * @param array|null $collections |
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| 72 | * @return IlluminateFluent |
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| 73 | */ |
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| 74 | public function addQueryToTransaction($query, $bindings = [], $collections = null) |
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| 75 | { |
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| 76 | //If transaction collections aren't provided we will try to extract them from the query. |
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| 77 | if (empty($collections)) { |
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| 78 | $collections = $this->extractTransactionCollections($query, $bindings, $collections); |
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| 79 | } |
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| 80 | |||
| 81 | // $query = addslashes($query); |
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| 82 | $jsCommand = 'db._query(aql`'.$query.'`'; |
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| 83 | if (! empty($bindings)) { |
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| 84 | $bindings = json_encode($bindings); |
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| 85 | $jsCommand .= ', '.$bindings; |
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| 86 | } |
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| 87 | $jsCommand .= ');'; |
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| 88 | $command = new IlluminateFluent([ |
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| 89 | 'name' => 'aqlQuery', |
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| 90 | 'command' => $jsCommand, |
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| 91 | 'collections' => $collections, |
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| 92 | ]); |
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| 93 | |||
| 94 | $this->addTransactionCommand($command); |
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| 95 | |||
| 96 | return $command; |
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| 97 | } |
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| 98 | |||
| 99 | /** |
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| 100 | * Transaction like a list of read collections to prevent possible read deadlocks. |
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| 101 | * Transactions require a list of write collections to prepare write locks. |
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| 102 | * |
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| 103 | * @param $query |
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| 104 | * @param $bindings |
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| 105 | * @param $collections |
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| 106 | * @return mixed |
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| 107 | */ |
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| 108 | public function extractTransactionCollections($query, $bindings, $collections) |
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| 109 | { |
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| 110 | //Extract write collections |
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| 111 | $collections = $this->extractReadCollections($query, $bindings, $collections); |
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| 112 | $collections = $this->extractWriteCollections($query, $bindings, $collections); |
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| 113 | |||
| 114 | return $collections; |
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| 115 | } |
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| 116 | |||
| 117 | /** |
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| 118 | * Extract collections that are read from in a query. Not required but can prevent deadlocks. |
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| 119 | * |
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| 120 | * @param $query |
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| 121 | * @param $bindings |
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| 122 | * @param $collections |
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| 123 | * @return mixed |
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| 124 | */ |
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| 125 | public function extractReadCollections($query, $bindings, $collections) |
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| 126 | { |
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| 127 | $extractedCollections = []; |
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| 128 | //WITH statement at the start of the query |
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| 129 | preg_match_all('/^(?:\s+?)WITH(?:\s+?)([\S\s]*?)(?:\s+?)FOR/mis', $query, $rawWithCollections); |
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| 130 | foreach ($rawWithCollections[1] as $key => $value) { |
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| 131 | $splits = preg_split("/\s*,\s*/", $value); |
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| 132 | $extractedCollections = array_merge($extractedCollections, $splits); |
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| 133 | } |
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| 134 | |||
| 135 | //FOR statements |
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| 136 | preg_match_all('/FOR(?:\s+?)(?:\w+)(?:\s+?)(?:IN|INTO)(?:\s+?)(?!OUTBOUND|INBOUND|ANY)(@?@?\w+(?!\.))/mis', $query, $rawForCollections); |
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| 137 | $extractedCollections = array_merge($extractedCollections, $rawForCollections[1]); |
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| 138 | |||
| 139 | //Document functions which require a document as their first argument |
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| 140 | preg_match_all('/(?:DOCUMENT\(|ATTRIBUTES\(|HAS\(|KEEP\(|LENGTH\(|MATCHES\(|PARSE_IDENTIFIER\(|UNSET\(|UNSET_RECURSIVE\(|VALUES\(|OUTBOUND|INBOUND|ANY)(?:\s+?)(?!\{)(?:\"|\'|\`)(@?@?\w+)\/(?:\w+)(?:\"|\'|\`)/mis', $query, $rawDocCollections); |
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| 141 | $extractedCollections = array_merge($extractedCollections, $rawDocCollections[1]); |
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| 142 | |||
| 143 | $extractedCollections = array_map('trim', $extractedCollections); |
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| 144 | |||
| 145 | $extractedCollections = $this->getCollectionByBinding($extractedCollections, $bindings); |
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| 146 | |||
| 147 | if (isset($collections['read'])) { |
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| 148 | $collections['read'] = array_merge($collections['read'], $extractedCollections); |
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| 149 | } else { |
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| 150 | $collections['read'] = $extractedCollections; |
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| 151 | } |
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| 152 | |||
| 153 | $collections['read'] = array_unique($collections['read']); |
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| 154 | |||
| 155 | return $collections; |
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| 156 | } |
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| 157 | |||
| 158 | /** |
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| 159 | * Extract collections that are written to in a query. |
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| 160 | * |
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| 161 | * @param $query |
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| 162 | * @param $bindings |
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| 163 | * @param $collections |
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| 164 | * @return mixed |
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| 165 | */ |
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| 166 | public function extractWriteCollections($query, $bindings, $collections) |
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| 167 | { |
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| 168 | preg_match_all('/(?:\s+?)(?:INSERT|REPLACE|UPDATE|REMOVE)(?:\s+?)(?:{(?:.*?)}|@?@?\w+?)(?:\s+?)(?:IN|INTO)(?:\s+?)(@?@?\w+)/mis', $query, $extractedCollections); |
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| 169 | $extractedCollections = array_map('trim', $extractedCollections[1]); |
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| 170 | |||
| 171 | $extractedCollections = $this->getCollectionByBinding($extractedCollections, $bindings); |
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| 172 | |||
| 173 | if (isset($collections['write'])) { |
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| 174 | $collections['write'] = array_merge($collections['write'], $extractedCollections); |
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| 175 | } else { |
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| 176 | $collections['write'] = $extractedCollections; |
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| 177 | } |
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| 178 | |||
| 179 | $collections['read'] = array_unique($collections['read']); |
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| 180 | |||
| 181 | return $collections; |
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| 182 | } |
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| 183 | |||
| 184 | /** |
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| 185 | * Get the collection names that are bound in a query. |
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| 186 | * |
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| 187 | * @param $collections |
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| 188 | * @param $bindings |
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| 189 | * @return mixed |
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| 190 | */ |
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| 191 | public function getCollectionByBinding($collections, $bindings) |
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| 192 | { |
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| 193 | foreach ($collections as $key => $collection) { |
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| 194 | if (strpos($collection, '@@') === 0 && isset($bindings[$collection])) { |
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| 195 | $collections[$key] = $bindings[$collection]; |
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| 196 | } |
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| 197 | } |
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| 198 | |||
| 199 | return $collections; |
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| 200 | } |
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| 201 | |||
| 202 | /** |
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| 203 | * Commit the current transaction. |
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| 204 | * |
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| 205 | * @param array $options |
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| 206 | * @param int $attempts |
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| 207 | * @return mixed |
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| 208 | * @throws Exception |
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| 209 | */ |
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| 210 | public function commit($options = [], $attempts = 1) |
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| 211 | { |
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| 212 | if (! $this->transactions > 0) { |
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| 213 | throw new \Exception('Transaction committed before starting one.'); |
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| 214 | } |
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| 215 | if (! isset($this->transactionCommands[$this->transactions]) || empty($this->transactionCommands[$this->transactions])) { |
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| 216 | throw new \Exception('Cannot commit an empty transaction.'); |
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| 217 | } |
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| 218 | |||
| 219 | $options['collections'] = $this->compileTransactionCollections(); |
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| 220 | |||
| 221 | $options['action'] = $this->compileTransactionAction(); |
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| 222 | |||
| 223 | $results = $this->executeTransaction($options, $attempts); |
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| 224 | |||
| 225 | $this->fireConnectionEvent('committed'); |
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| 226 | |||
| 227 | return $results; |
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| 228 | } |
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| 229 | |||
| 230 | public function executeTransaction($options, $attempts = 1) |
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| 231 | { |
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| 232 | $results = null; |
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| 233 | |||
| 234 | $this->arangoTransaction = new ArangoTransaction($this->arangoConnection, $options); |
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| 235 | |||
| 236 | for ($currentAttempt = 1; $currentAttempt <= $attempts; $currentAttempt++) { |
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| 237 | try { |
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| 238 | $results = $this->arangoTransaction->execute(); |
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| 239 | |||
| 240 | $this->transactions--; |
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| 241 | } catch (Exception $e) { |
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| 242 | $this->fireConnectionEvent('rollingBack'); |
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| 243 | |||
| 244 | $results = $this->handleTransactionException($e, $currentAttempt, $attempts); |
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| 245 | } |
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| 246 | } |
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| 247 | |||
| 248 | return $results; |
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| 249 | } |
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| 250 | |||
| 251 | /** |
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| 252 | * Handle an exception encountered when running a transacted statement. |
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| 253 | * |
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| 254 | * @param Exception $e |
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| 255 | * @param integer $currentAttempt |
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| 256 | * @param integer $attempts |
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| 257 | * @return mixed |
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| 258 | */ |
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| 259 | protected function handleTransactionException($e, $currentAttempt, $attempts) |
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| 260 | { |
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| 261 | $retry = false; |
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| 262 | // If the failure was due to a lost connection we can just try again. |
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| 263 | if ($this->causedByLostConnection($e)) { |
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| 264 | $this->reconnect(); |
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| 265 | $retry = true; |
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| 266 | } |
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| 267 | |||
| 268 | // Retry if the failure was caused by a deadlock or ArangoDB suggests we try so. |
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| 269 | // We can check if we have exceeded the maximum attempt count for this and if |
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| 270 | // we haven't we will return and try this transaction again. |
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| 271 | if ($this->causedByDeadlock($e) && |
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| 272 | $currentAttempt < $attempts) { |
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| 273 | $retry = true; |
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| 274 | } |
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| 275 | |||
| 276 | if ($retry) { |
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| 277 | return $this->arangoTransaction->execute(); |
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| 278 | } |
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| 279 | |||
| 280 | throw $e; |
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| 281 | } |
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| 282 | |||
| 283 | /** |
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| 284 | * compile an array of unique collections that are used to read from and/or write to. |
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| 285 | * |
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| 286 | * @return array |
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| 287 | */ |
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| 288 | public function compileTransactionCollections() |
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| 289 | { |
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| 290 | $result['write'] = []; |
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| 291 | $result['read'] = []; |
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| 292 | |||
| 293 | $commands = $this->transactionCommands[$this->transactions]; |
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| 294 | |||
| 295 | foreach ($commands as $command) { |
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| 296 | if (isset($command->collections['write'])) { |
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| 297 | $write = $command->collections['write']; |
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| 298 | if (is_string($write)) { |
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| 299 | $write = (array) $write; |
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| 300 | } |
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| 301 | $result['write'] = array_merge($result['write'], $write); |
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| 302 | } |
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| 303 | if (isset($command->collections['read'])) { |
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| 304 | $read = $command->collections['read']; |
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| 305 | if (is_string($read)) { |
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| 306 | $read = (array) $read; |
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| 307 | } |
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| 308 | $result['read'] = array_merge($result['write'], $read); |
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| 309 | } |
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| 310 | } |
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| 311 | |||
| 312 | $result['read'] = array_merge($result['read'], $result['write']); |
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| 313 | |||
| 314 | $result['write'] = array_filter(array_unique($result['write'])); |
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| 315 | if (empty($result['write'])) { |
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| 316 | unset($result['write']); |
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| 317 | } |
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| 318 | |||
| 319 | $result['read'] = array_filter(array_unique($result['read'])); |
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| 320 | if (empty($result['read'])) { |
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| 321 | unset($result['read']); |
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| 322 | } |
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| 323 | |||
| 324 | $result = array_filter($result); |
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| 325 | |||
| 326 | return $result; |
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| 327 | } |
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| 328 | |||
| 329 | public function compileTransactionAction() |
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| 330 | { |
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| 331 | $commands = collect($this->transactionCommands[$this->transactions]); |
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| 332 | |||
| 333 | $action = "function () { var db = require('@arangodb').db; "; |
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| 334 | $action .= $commands->implode('command', ' '); |
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| 335 | $action .= ' }'; |
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| 336 | |||
| 337 | return $action; |
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| 338 | } |
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| 339 | |||
| 340 | /** |
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| 341 | * Handle an exception from a rollback. |
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| 342 | * |
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| 343 | * @param \Exception $e |
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| 344 | * |
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| 345 | * @throws \Exception |
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| 346 | */ |
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| 347 | protected function handleRollBackException($e) |
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| 348 | { |
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| 349 | if ($this->causedByLostConnection($e)) { |
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| 350 | $this->transactions = 0; |
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| 351 | } |
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| 352 | |||
| 353 | throw $e; |
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| 354 | } |
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| 355 | |||
| 356 | /** |
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| 357 | * Get the number of active transactions. |
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| 358 | * |
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| 359 | * @return int |
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| 360 | */ |
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| 361 | public function transactionLevel() |
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| 362 | { |
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| 363 | return $this->transactions; |
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| 364 | } |
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| 365 | |||
| 366 | public function getTransactionCommands() |
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| 367 | { |
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| 368 | return $this->transactionCommands; |
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| 369 | } |
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| 370 | |||
| 371 | //Override unused trait transaction functions with dummy methods |
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| 372 | |||
| 373 | /** |
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| 374 | * Dummy. |
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| 375 | * |
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| 376 | * @param $e |
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| 377 | */ |
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| 378 | public function handleBeginTransactionException($e) |
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| 379 | { |
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| 380 | // |
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| 381 | } |
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| 382 | |||
| 383 | /** |
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| 384 | * Dummy override: Rollback the active database transaction. |
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| 385 | * |
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| 386 | * @param int|null $toLevel |
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| 387 | * @return void |
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| 388 | * |
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| 389 | * @throws \Exception |
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| 390 | */ |
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| 391 | public function rollBack($toLevel = null) |
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| 392 | { |
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| 393 | // |
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| 394 | } |
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| 395 | |||
| 396 | /** |
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| 397 | * Dummy override: ArangoDB rolls back the entire transaction on a failure. |
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| 398 | * |
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| 399 | * @param int $toLevel |
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| 400 | * @return void |
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| 401 | */ |
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| 402 | protected function performRollBack($toLevel) |
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| 403 | { |
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| 404 | // |
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| 405 | } |
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| 406 | |||
| 407 | /** |
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| 408 | * Create a save point within the database. |
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| 409 | * Not supported by ArangoDB(?). |
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| 410 | * |
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| 411 | * @return void |
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| 412 | */ |
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| 413 | protected function createSavepoint() |
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| 414 | { |
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| 415 | // |
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| 416 | } |
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| 417 | } |
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| 418 |
Adding an explicit array definition is generally preferable to implicit array definition as it guarantees a stable state of the code.
Let’s take a look at an example:
As you can see in this example, the array
$myArrayis initialized the first time when the foreach loop is entered. You can also see that the value of thebarkey is only written conditionally; thus, its value might result from a previous iteration.This might or might not be intended. To make your intention clear, your code more readible and to avoid accidental bugs, we recommend to add an explicit initialization $myArray = array() either outside or inside the foreach loop.