Code Coverage |
||||||||||
Lines |
Functions and Methods |
Classes and Traits |
||||||||
| Total | |
0.00% |
0 / 77 |
|
0.00% |
0 / 7 |
CRAP | |
0.00% |
0 / 1 |
| QtiTimeStoragePackedFormat | |
0.00% |
0 / 77 |
|
0.00% |
0 / 7 |
756 | |
0.00% |
0 / 1 |
| getFormat | |
0.00% |
0 / 1 |
|
0.00% |
0 / 1 |
2 | |||
| getVersion | |
0.00% |
0 / 1 |
|
0.00% |
0 / 1 |
2 | |||
| getEpoch | |
0.00% |
0 / 2 |
|
0.00% |
0 / 1 |
2 | |||
| packTimeLine | |
0.00% |
0 / 24 |
|
0.00% |
0 / 1 |
42 | |||
| unpackTimeLine | |
0.00% |
0 / 15 |
|
0.00% |
0 / 1 |
42 | |||
| encode | |
0.00% |
0 / 11 |
|
0.00% |
0 / 1 |
20 | |||
| decode | |
0.00% |
0 / 23 |
|
0.00% |
0 / 1 |
72 | |||
| 1 | <?php |
| 2 | |
| 3 | /** |
| 4 | * This program is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU General Public License |
| 6 | * as published by the Free Software Foundation; under version 2 |
| 7 | * of the License (non-upgradable). |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
| 17 | * |
| 18 | * Copyright (c) 2017 (original work) Open Assessment Technologies SA ; |
| 19 | * |
| 20 | */ |
| 21 | |
| 22 | namespace oat\taoQtiTest\models\runner\time\storageFormat; |
| 23 | |
| 24 | use oat\taoQtiTest\models\runner\time\AdjustmentMap; |
| 25 | use oat\taoQtiTest\models\runner\time\QtiTimeLine; |
| 26 | use oat\taoTests\models\runner\time\TimeLine; |
| 27 | use oat\taoTests\models\runner\time\TimePoint; |
| 28 | use oat\taoTests\models\runner\time\TimerAdjustmentMapInterface; |
| 29 | |
| 30 | /** |
| 31 | * Class QtiTimeStoragePackedFormat |
| 32 | * |
| 33 | * Encode/decode QtiTimer using JSON format. |
| 34 | * Apply a compression on the QtiTimeLine entries to reduce the weight of the encoded data. |
| 35 | * |
| 36 | * Applied format: |
| 37 | * |
| 38 | * ``` |
| 39 | * { |
| 40 | * // For each tags set an index that points to each linked timestamps. |
| 41 | * // Each index value is the offset of the timestamp in the "points" array. |
| 42 | * "index": { |
| 43 | * "tag1": [0, 1, 2, 6, ...], |
| 44 | * "tag2": [0, 2, 4, ...], |
| 45 | * ... |
| 46 | * "tagN": [100, 101, 110, 111, ...], |
| 47 | * }, |
| 48 | * |
| 49 | * // A list of tags that applies for all timestamps. |
| 50 | * "tags": [ |
| 51 | * "global-tag-1", |
| 52 | * "global-tag-2", |
| 53 | * ... |
| 54 | * "global-tag-N", |
| 55 | * ], |
| 56 | * |
| 57 | * // A flat list of timestamps, their tags are moved into the index map. |
| 58 | * // Each timestamp is reduced by a reference value to minimize the final size. |
| 59 | * "points": [ |
| 60 | * [target, type, timestamp - todayTimestamp], |
| 61 | * [target, type, timestamp - todayTimestamp], |
| 62 | * ... |
| 63 | * [target, type, timestamp - todayTimestamp] |
| 64 | * ], |
| 65 | * |
| 66 | * // The arbitrary reference value that has been used to reduce the timestamps. |
| 67 | * // Usually it is the timestamp of today morning at 00:00. |
| 68 | * // (could be improved to be based on the assessment start time) |
| 69 | * "epoch": todayTimestamp |
| 70 | * } |
| 71 | * ``` |
| 72 | * |
| 73 | * @package oat\taoQtiTest\models\runner\time\storageFormat |
| 74 | * @author Jean-Sébastien Conan <jean-sebastien@taotesting.com> |
| 75 | */ |
| 76 | class QtiTimeStoragePackedFormat extends QtiTimeStorageJsonFormat |
| 77 | { |
| 78 | use QtiTimeStorageObjectDecodingTrait; |
| 79 | |
| 80 | /** |
| 81 | * A storage key added to the sored data set to keep format type |
| 82 | */ |
| 83 | public const STORAGE_KEY_FORMAT = 'format'; |
| 84 | |
| 85 | /** |
| 86 | * A storage key added to the sored data set to keep version info |
| 87 | */ |
| 88 | public const STORAGE_KEY_VERSION = 'version'; |
| 89 | |
| 90 | /** |
| 91 | * The storage key for the TimeLine index in the packed format |
| 92 | */ |
| 93 | public const STORAGE_KEY_TIMELINE_INDEX = 'index'; |
| 94 | |
| 95 | /** |
| 96 | * The storage key for the TimeLine tags in the packed format |
| 97 | */ |
| 98 | public const STORAGE_KEY_TIMELINE_TAGS = 'tags'; |
| 99 | |
| 100 | /** |
| 101 | * The storage key for the TimeLine points in the packed format |
| 102 | */ |
| 103 | public const STORAGE_KEY_TIMELINE_POINTS = 'points'; |
| 104 | |
| 105 | /** |
| 106 | * The storage key for the timestamp reference in the packed format |
| 107 | */ |
| 108 | public const STORAGE_KEY_TIMELINE_EPOCH = 'epoch'; |
| 109 | |
| 110 | /** |
| 111 | * The type of format managed by this class |
| 112 | */ |
| 113 | public const STORAGE_FORMAT = 'pack'; |
| 114 | |
| 115 | /** |
| 116 | * The version of the format. Could be useful in case of changes to take care of legacy. |
| 117 | */ |
| 118 | public const STORAGE_VERSION = 1; |
| 119 | |
| 120 | /** |
| 121 | * The type of format applied by this class |
| 122 | * @return string |
| 123 | */ |
| 124 | public function getFormat() |
| 125 | { |
| 126 | return static::STORAGE_FORMAT; |
| 127 | } |
| 128 | |
| 129 | /** |
| 130 | * The version of the packing format applied |
| 131 | * @return int |
| 132 | */ |
| 133 | public function getVersion() |
| 134 | { |
| 135 | return static::STORAGE_VERSION; |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * The reference value used to compress the timestamps |
| 140 | * @return int |
| 141 | */ |
| 142 | public function getEpoch() |
| 143 | { |
| 144 | // align the reference value with the timestamp of today morning. |
| 145 | $today = time(); |
| 146 | return $today - $today % 86400; |
| 147 | } |
| 148 | |
| 149 | /** |
| 150 | * Packs a TimeLine in order to reduce the storage footprint |
| 151 | * @param TimeLine $timeLine |
| 152 | * @return array |
| 153 | */ |
| 154 | protected function packTimeLine(&$timeLine) |
| 155 | { |
| 156 | $epoch = $this->getEpoch(); |
| 157 | $data = [ |
| 158 | self::STORAGE_KEY_TIMELINE_INDEX => [], |
| 159 | self::STORAGE_KEY_TIMELINE_TAGS => [], |
| 160 | self::STORAGE_KEY_TIMELINE_POINTS => [], |
| 161 | self::STORAGE_KEY_TIMELINE_EPOCH => $epoch, |
| 162 | ]; |
| 163 | |
| 164 | // Will split tags from the list of TimePoint, and put them into a dedicated index. |
| 165 | // The other TimePoint info are put in a simple array with predictable order, this way: |
| 166 | // [target, type, timestamp]. |
| 167 | // To save more space a reference value is removed from each timestamp. |
| 168 | $index = 0; |
| 169 | foreach ($timeLine->getPoints() as &$point) { |
| 170 | /** @var TimePoint $point */ |
| 171 | $data[self::STORAGE_KEY_TIMELINE_POINTS][$index] = [ |
| 172 | $point->getTarget(), |
| 173 | $point->getType(), |
| 174 | round($point->getTimestamp() - $epoch, 6), |
| 175 | ]; |
| 176 | |
| 177 | foreach ($point->getTags() as &$tag) { |
| 178 | $data[self::STORAGE_KEY_TIMELINE_INDEX][$tag][] = $index; |
| 179 | } |
| 180 | |
| 181 | $index++; |
| 182 | } |
| 183 | |
| 184 | // try to reduce the size of the index by simplifying those that target all TimePoint |
| 185 | if ($index) { |
| 186 | foreach ($data[self::STORAGE_KEY_TIMELINE_INDEX] as $tag => &$list) { |
| 187 | if (count($list) == $index) { |
| 188 | unset($data[self::STORAGE_KEY_TIMELINE_INDEX][$tag]); |
| 189 | $data[self::STORAGE_KEY_TIMELINE_TAGS][] = $tag; |
| 190 | } |
| 191 | } |
| 192 | } else { |
| 193 | $data = []; |
| 194 | } |
| 195 | |
| 196 | return $data; |
| 197 | } |
| 198 | |
| 199 | /** |
| 200 | * Unpack a dataset to a workable TimeLine |
| 201 | * @param array $data |
| 202 | * @return TimeLine |
| 203 | */ |
| 204 | protected function unpackTimeLine(&$data) |
| 205 | { |
| 206 | $timeLine = new QtiTimeLine(); |
| 207 | |
| 208 | // the stored data can be packed or not |
| 209 | if (isset($data[self::STORAGE_KEY_TIMELINE_POINTS])) { |
| 210 | // get the reference value used to compress the timestamps |
| 211 | $epoch = 0; |
| 212 | if (isset($data[self::STORAGE_KEY_TIMELINE_EPOCH])) { |
| 213 | $epoch = $data[self::STORAGE_KEY_TIMELINE_EPOCH]; |
| 214 | } |
| 215 | |
| 216 | // rebuild the TimeLine from the list of stored TimePoint |
| 217 | $tags = $data[self::STORAGE_KEY_TIMELINE_TAGS]; |
| 218 | foreach ($data[self::STORAGE_KEY_TIMELINE_POINTS] as &$dataPoint) { |
| 219 | $point = new TimePoint($tags, $dataPoint[2] + $epoch, $dataPoint[1], $dataPoint[0]); |
| 220 | $timeLine->add($point); |
| 221 | } |
| 222 | |
| 223 | // reassign the tags from the stored index |
| 224 | $points = $timeLine->getPoints(); |
| 225 | foreach ($data[self::STORAGE_KEY_TIMELINE_INDEX] as $tag => &$list) { |
| 226 | foreach ($list as $index) { |
| 227 | $points[$index]->addTag($tag); |
| 228 | } |
| 229 | } |
| 230 | } else { |
| 231 | $timeLine->fromArray($data); |
| 232 | } |
| 233 | |
| 234 | return $timeLine; |
| 235 | } |
| 236 | |
| 237 | /** |
| 238 | * Encode a dataset with the managed format. |
| 239 | * @param mixed $data |
| 240 | * @return string |
| 241 | */ |
| 242 | public function encode($data) |
| 243 | { |
| 244 | if (is_array($data)) { |
| 245 | $encodedData = [ |
| 246 | self::STORAGE_KEY_FORMAT => $this->getFormat(), |
| 247 | self::STORAGE_KEY_VERSION => $this->getVersion(), |
| 248 | ]; |
| 249 | |
| 250 | foreach ($data as $key => &$value) { |
| 251 | if ($value instanceof TimeLine) { |
| 252 | $encodedData[$key] = $this->packTimeLine($value); |
| 253 | } else { |
| 254 | $encodedData[$key] = &$value; |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | return json_encode($encodedData); |
| 259 | } |
| 260 | |
| 261 | return json_encode($data); |
| 262 | } |
| 263 | |
| 264 | /** |
| 265 | * Decode a string encoded with the managed format. |
| 266 | * @param string $data |
| 267 | * @return mixed |
| 268 | */ |
| 269 | public function decode($data) |
| 270 | { |
| 271 | $decodedData = json_decode($data, true); |
| 272 | |
| 273 | // fallback for old storage that uses PHP serialize format |
| 274 | if (is_null($decodedData) && $data) { |
| 275 | $decodedData = unserialize($data); |
| 276 | } |
| 277 | |
| 278 | if (is_array($decodedData)) { |
| 279 | if (isset($decodedData[self::STORAGE_KEY_FORMAT])) { |
| 280 | if ($decodedData[self::STORAGE_KEY_FORMAT] != $this->getFormat()) { |
| 281 | \common_Logger::w( |
| 282 | sprintf( |
| 283 | 'QtiTimeStorage: wrong decoder applied! (Expected: %s, Applied: %s)', |
| 284 | $decodedData[self::STORAGE_KEY_FORMAT], |
| 285 | $this->getFormat() |
| 286 | ) |
| 287 | ); |
| 288 | } |
| 289 | |
| 290 | if ( |
| 291 | array_key_exists(self::STORAGE_KEY_TIME_LINE, $decodedData) |
| 292 | && !$decodedData[self::STORAGE_KEY_TIME_LINE] instanceof TimeLine |
| 293 | ) { |
| 294 | $decodedData[self::STORAGE_KEY_TIME_LINE] = $this->unpackTimeLine( |
| 295 | $decodedData[self::STORAGE_KEY_TIME_LINE] |
| 296 | ); |
| 297 | } |
| 298 | |
| 299 | unset($decodedData[self::STORAGE_KEY_FORMAT]); |
| 300 | unset($decodedData[self::STORAGE_KEY_VERSION]); |
| 301 | } else { |
| 302 | $decodedData = $this->decodeTimeline($decodedData); |
| 303 | } |
| 304 | $decodedData = $this->decodeAdjustmentMap($decodedData); |
| 305 | } |
| 306 | |
| 307 | return $decodedData; |
| 308 | } |
| 309 | } |