DataLoader::scheduleDispatch() - Code Metrics - Inspection of "Update .scrutinizer.yml" - lordthorzonus/php-dataloader - Measure and Improve Code Quality continuously with Scrutinizer

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by Juuso

created 2019-04-08 07:47 UTC

DataLoader::scheduleDispatch() A

↳ Parent: DataLoader

Complexity

Conditions	2
Paths	2

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	8
CRAP Score	2

Importance

Changes

Metric	Value
dl	0
loc	14
ccs	8
cts	8
cp	1
rs	9.7998
c	0
b	0
f	0
cc	2
nc	2
nop	0
crap	2

<?php

declare(strict_types=1);

namespace leinonen\DataLoader;

use React\Promise\Promise;
use function React\Promise\all;
use function React\Promise\reject;
use React\EventLoop\LoopInterface;
use function React\Promise\resolve;
use React\Promise\ExtendedPromiseInterface;

final class DataLoader implements DataLoaderInterface
{
    /**
     * @var callable
     */
    private $batchLoadFunction;

    /**
     * @var array
     */
    private $promiseQueue = [];

    /**
     * @var CacheMapInterface
     */
    private $promiseCache;

    /**
     * @var LoopInterface
     */
    private $eventLoop;

    /**
     * @var DataLoaderOptions
     */
    private $options;

    /**
     * Initiates a new DataLoader.
     *
     * @param callable $batchLoadFunction The function which will be called for the batch loading.
     * It must accept an array of keys and returns a Promise which resolves to an array of values.
     * @param LoopInterface $loop
     * @param CacheMapInterface $cacheMap
     * @param null|DataLoaderOptions $options
     */
    public function __construct(
        callable $batchLoadFunction,
        LoopInterface $loop,
        CacheMapInterface $cacheMap,
        DataLoaderOptions $options = null
    ) {
        $this->batchLoadFunction = $batchLoadFunction;
        $this->eventLoop = $loop;
        $this->promiseCache = $cacheMap;
        $this->options = $options ?? new DataLoaderOptions();
    }

    /**
     * {@inheritdoc}
     */
    public function load($key): ExtendedPromiseInterface
    {
        if ($key === null) {
            throw new \InvalidArgumentException(self::class . '::load must be called with a value, but got null');
        }

        if ($this->options->shouldCache() && $this->promiseCache->get($key)) {
            return $this->promiseCache->get($key);
        }

        $promise = new Promise(
            function (callable $resolve, callable $reject) use ($key) {
                $this->promiseQueue[] = [
                    'key' => $key,
                    'resolve' => $resolve,
                    'reject' => $reject,
                ];

                if (\count($this->promiseQueue) === 1) {
                    $this->scheduleDispatch();
                }
            }
        );

        if ($this->options->shouldCache()) {
            $this->promiseCache->set($key, $promise);
        }

        return $promise;
    }

    /**
     * {@inheritdoc}
     */
    public function loadMany(array $keys): ExtendedPromiseInterface
    {
        return all(
            \array_map(
                function ($key) {
                    return $this->load($key);
                },
                $keys
            )
        );
    }

    /**
     * {@inheritdoc}
     */
    public function clear($key): void
    {
        $this->promiseCache->delete($key);
    }

    /**
     * {@inheritdoc}
     */
    public function clearAll(): void
    {
        $this->promiseCache->clear();
    }

    /**
     * {@inheritdoc}
     */
    public function prime($key, $value): void
    {
        if (! $this->promiseCache->get($key)) {
            // Cache a rejected promise if the value is an Exception, in order to match
            // the behavior of load($key).
            $promise = $value instanceof \Exception ? reject($value) : resolve($value);

            $this->promiseCache->set($key, $promise);
        }
    }

    /**
     * Schedules the dispatch to happen on the next tick of the EventLoop
     * If batching is disabled, schedule the dispatch immediately.
     *
     * @return void
     */
    private function scheduleDispatch(): void
    {
        if ($this->options->shouldBatch()) {
            $this->eventLoop->futureTick(
                function () {
                    $this->dispatchQueue();
                }
            );

            return;
        }

        $this->dispatchQueue();
    }

    /**
     * Resets and dispatches the DataLoaders queue.
     *
     * @return void
     */
    private function dispatchQueue(): void
    {
        $queue = $this->promiseQueue;
        $this->promiseQueue = [];

        $maxBatchSize = $this->options->getMaxBatchSize();

        if ($maxBatchSize !== null && $maxBatchSize > 0 && $maxBatchSize < count($queue)) {
            $this->dispatchQueueInMultipleBatches($queue, $maxBatchSize);
        } else {
            $this->dispatchQueueBatch($queue);
        }
    }

    /**
     * Dispatches a batch of a queue. The given batch can also be the whole queue.
     *
     * @param array $batch
     */
    private function dispatchQueueBatch($batch)
    {
        $keys = \array_column($batch, 'key');
        $batchLoadFunction = $this->batchLoadFunction;

        /** @var Promise $batchPromise */
        $batchPromise = $batchLoadFunction($keys);

        try {
            $this->validateBatchPromise($batchPromise);
        } catch (DataLoaderException $exception) {
            return $this->handleFailedDispatch($batch, $exception);
        }

        $batchPromise->then(
            function ($values) use ($batch, $keys) {
                $this->validateBatchPromiseOutput($values, $keys);
                $this->handleSuccessfulDispatch($batch, $values);
            }
        )->then(null, function ($error) use ($batch) {
            $this->handleFailedDispatch($batch, $error);
        });
    }

    /**
     * Dispatches the given queue in multiple batches.
     *
     * @param array $queue
     * @param int $maxBatchSize
     *
     * @return void
     */
    private function dispatchQueueInMultipleBatches(array $queue, $maxBatchSize): void
    {
        $numberOfBatchesToDispatch = \count($queue) / $maxBatchSize;

        for ($i = 0; $i < $numberOfBatchesToDispatch; $i++) {
            $this->dispatchQueueBatch(
                \array_slice($queue, $i * $maxBatchSize, $maxBatchSize)
            );
        }
    }

    /**
     * Handles the batch by resolving the promises and rejecting ones that return Exceptions.
     *
     * @param array $batch
     * @param array $values
     */
    private function handleSuccessfulDispatch(array $batch, array $values): void
    {
        foreach ($batch as $index => $queueItem) {
            $value = $values[$index];
            if ($value instanceof \Exception) {
                $queueItem['reject']($value);
            } else {
                $queueItem['resolve']($value);
            }
        }
    }

    /**
     * Handles the failed batch dispatch.
     *
     * @param array $batch
     * @param \Exception $error
     */
    private function handleFailedDispatch(array $batch, \Exception $error)
    {
        foreach ($batch as $index => $queueItem) {
            // We don't want to cache individual loads if the entire batch dispatch fails.
            $this->clear($queueItem['key']);
            $queueItem['reject']($error);
        }
    }

    /**
     * Validates the batch promise's output.
     *
     * @param array $values Values from resolved promise.
     * @param array $keys Keys which the DataLoaders load was called with
     *
     * @throws DataLoaderException
     */
    private function validateBatchPromiseOutput($values, $keys): void
    {
        if (! \is_array($values)) {
            throw new DataLoaderException(
                self::class . ' must be constructed with a function which accepts ' .
                'an array of keys and returns a Promise which resolves to an array of values ' .
                \sprintf('not return a Promise: %s.', \gettype($values))
            );
        }

        if (\count($values) !== \count($keys)) {
            throw new DataLoaderException(
                self::class . ' must be constructed with a function which accepts ' .
                'an array of keys and returns a Promise which resolves to an array of values, but ' .
                'the function did not return a Promise of an array of the same length as the array of keys.' .
                \sprintf("\n Keys: %s\n Values: %s\n", \count($keys), \count($values))
            );
        }
    }

    /**
     * Validates the batch promise returned from the batch load function.
     *
     * @param $batchPromise
     *
     * @throws DataLoaderException
     */
    private function validateBatchPromise($batchPromise): void
    {
        if (! $batchPromise || ! \is_callable([$batchPromise, 'then'])) {
            throw new DataLoaderException(
                self::class . ' must be constructed with a function which accepts ' .
                'an array of keys and returns a Promise which resolves to an array of values ' .
                \sprintf('the function returned %s.', \gettype($batchPromise))
            );
        }
    }
}


1		<?php
2
3		declare(strict_types=1);
4
5		namespace leinonen\DataLoader;
6
7		use React\Promise\Promise;
8		use function React\Promise\all;
9		use function React\Promise\reject;
10		use React\EventLoop\LoopInterface;
11		use function React\Promise\resolve;
12		use React\Promise\ExtendedPromiseInterface;
13
14		final class DataLoader implements DataLoaderInterface
15		{
16		/**
17		* @var callable
18		*/
19		private $batchLoadFunction;
20
21		/**
22		* @var array
23		*/
24		private $promiseQueue = [];
25
26		/**
27		* @var CacheMapInterface
28		*/
29		private $promiseCache;
30
31		/**
32		* @var LoopInterface
33		*/
34		private $eventLoop;
35
36		/**
37		* @var DataLoaderOptions
38		*/
39		private $options;
40
41		/**
42		* Initiates a new DataLoader.
43		*
44		* @param callable $batchLoadFunction The function which will be called for the batch loading.
45		* It must accept an array of keys and returns a Promise which resolves to an array of values.
46		* @param LoopInterface $loop
47		* @param CacheMapInterface $cacheMap
48		* @param null\|DataLoaderOptions $options
49		*/
50	32	public function __construct(
51		callable $batchLoadFunction,
52		LoopInterface $loop,
53		CacheMapInterface $cacheMap,
54		DataLoaderOptions $options = null
55		) {
56	32	$this->batchLoadFunction = $batchLoadFunction;
57	32	$this->eventLoop = $loop;
58	32	$this->promiseCache = $cacheMap;
59	32	$this->options = $options ?? new DataLoaderOptions();
60	32	}
61
62		/**
63		* {@inheritdoc}
64		*/
65	32	public function load($key): ExtendedPromiseInterface
66		{
67	32	if ($key === null) {
68	2	throw new \InvalidArgumentException(self::class . '::load must be called with a value, but got null');
69		}
70
71	30	if ($this->options->shouldCache() && $this->promiseCache->get($key)) {
72	9	return $this->promiseCache->get($key);
73		}
74
75	29	$promise = new Promise(
76		function (callable $resolve, callable $reject) use ($key) {
77	29	$this->promiseQueue[] = [
78	29	'key' => $key,
79	29	'resolve' => $resolve,
80	29	'reject' => $reject,
81		];
82
83	29	if (\count($this->promiseQueue) === 1) {
84	29	$this->scheduleDispatch();
85		}
86	29	}
87		);
88
89	29	if ($this->options->shouldCache()) {
90	28	$this->promiseCache->set($key, $promise);
91		}
92
93	29	return $promise;
94		}
95
96		/**
97		* {@inheritdoc}
98		*/
99	2	public function loadMany(array $keys): ExtendedPromiseInterface
100		{
101	2	return all(
102	2	\array_map(
103		function ($key) {
104	2	return $this->load($key);
105	2	},
106	2	$keys
107		)
108		);
109		}
110
111		/**
112		* {@inheritdoc}
113		*/
114	11	public function clear($key): void
115		{
116	11	$this->promiseCache->delete($key);
117	11	}
118
119		/**
120		* {@inheritdoc}
121		*/
122	1	public function clearAll(): void
123		{
124	1	$this->promiseCache->clear();
125	1	}
126
127		/**
128		* {@inheritdoc}
129		*/
130	4	public function prime($key, $value): void
131		{
132	4	if (! $this->promiseCache->get($key)) {
133		// Cache a rejected promise if the value is an Exception, in order to match
134		// the behavior of load($key).
135	4	$promise = $value instanceof \Exception ? reject($value) : resolve($value);
136
137	4	$this->promiseCache->set($key, $promise);
138		}
139	4	}
140
141		/**
142		* Schedules the dispatch to happen on the next tick of the EventLoop
143		* If batching is disabled, schedule the dispatch immediately.
144		*
145		* @return void
146		*/
147	29	private function scheduleDispatch(): void
148		{
149	29	if ($this->options->shouldBatch()) {
150	28	$this->eventLoop->futureTick(
151		function () {
152	27	$this->dispatchQueue();
153	28	}
154		);
155
156	28	return;
157		}
158
159	1	$this->dispatchQueue();
160	1	}
161
162		/**
163		* Resets and dispatches the DataLoaders queue.
164		*
165		* @return void
166		*/
167	28	private function dispatchQueue(): void
168		{
169	28	$queue = $this->promiseQueue;
170	28	$this->promiseQueue = [];
171
172	28	$maxBatchSize = $this->options->getMaxBatchSize();
173
174	28	if ($maxBatchSize !== null && $maxBatchSize > 0 && $maxBatchSize < count($queue)) {
175	1	$this->dispatchQueueInMultipleBatches($queue, $maxBatchSize);
176		} else {
177	27	$this->dispatchQueueBatch($queue);
178		}
179	28	}
180
181		/**
182		* Dispatches a batch of a queue. The given batch can also be the whole queue.
183		*
184		* @param array $batch
185		*/
186	28	private function dispatchQueueBatch($batch)
187		{
188	28	$keys = \array_column($batch, 'key');
189	28	$batchLoadFunction = $this->batchLoadFunction;
190
191		/** @var Promise $batchPromise */
192	28	$batchPromise = $batchLoadFunction($keys);
193
194		try {
195	28	$this->validateBatchPromise($batchPromise);
196	4	} catch (DataLoaderException $exception) {
197	4	return $this->handleFailedDispatch($batch, $exception);
198		}
199
200	24	$batchPromise->then(
201		function ($values) use ($batch, $keys) {
202	23	$this->validateBatchPromiseOutput($values, $keys);
203	21	$this->handleSuccessfulDispatch($batch, $values);
204	24	}
205		)->then(null, function ($error) use ($batch) {
206	3	$this->handleFailedDispatch($batch, $error);
207	24	});
208	24	}
209
210		/**
211		* Dispatches the given queue in multiple batches.
212		*
213		* @param array $queue
214		* @param int $maxBatchSize
215		*
216		* @return void
217		*/
218	1	private function dispatchQueueInMultipleBatches(array $queue, $maxBatchSize): void
219		{
220	1	$numberOfBatchesToDispatch = \count($queue) / $maxBatchSize;
221
222	1	for ($i = 0; $i < $numberOfBatchesToDispatch; $i++) {
223	1	$this->dispatchQueueBatch(
224	1	\array_slice($queue, $i * $maxBatchSize, $maxBatchSize)
225		);
226		}
227	1	}
228
229		/**
230		* Handles the batch by resolving the promises and rejecting ones that return Exceptions.
231		*
232		* @param array $batch
233		* @param array $values
234		*/
235	21	private function handleSuccessfulDispatch(array $batch, array $values): void
236		{
237	21	foreach ($batch as $index => $queueItem) {
238	21	$value = $values[$index];
239	21	if ($value instanceof \Exception) {
240	4	$queueItem['reject']($value);
241		} else {
242	21	$queueItem['resolve']($value);
243		}
244		}
245	21	}
246
247		/**
248		* Handles the failed batch dispatch.
249		*
250		* @param array $batch
251		* @param \Exception $error
252		*/
253	7	private function handleFailedDispatch(array $batch, \Exception $error)
254		{
255	7	foreach ($batch as $index => $queueItem) {
256		// We don't want to cache individual loads if the entire batch dispatch fails.
257	7	$this->clear($queueItem['key']);
258	7	$queueItem['reject']($error);
259		}
260	7	}
261
262		/**
263		* Validates the batch promise's output.
264		*
265		* @param array $values Values from resolved promise.
266		* @param array $keys Keys which the DataLoaders load was called with
267		*
268		* @throws DataLoaderException
269		*/
270	23	private function validateBatchPromiseOutput($values, $keys): void
271		{
272	23	if (! \is_array($values)) {
273	1	throw new DataLoaderException(
274		self::class . ' must be constructed with a function which accepts ' .
275		'an array of keys and returns a Promise which resolves to an array of values ' .
276	1	\sprintf('not return a Promise: %s.', \gettype($values))
277		);
278		}
279
280	22	if (\count($values) !== \count($keys)) {
281	1	throw new DataLoaderException(
282		self::class . ' must be constructed with a function which accepts ' .
283		'an array of keys and returns a Promise which resolves to an array of values, but ' .
284		'the function did not return a Promise of an array of the same length as the array of keys.' .
285	1	\sprintf("\n Keys: %s\n Values: %s\n", \count($keys), \count($values))
286		);
287		}
288	21	}
289
290		/**
291		* Validates the batch promise returned from the batch load function.
292		*
293		* @param $batchPromise
294		*
295		* @throws DataLoaderException
296		*/
297	28	private function validateBatchPromise($batchPromise): void
298		{
299	28	if (! $batchPromise \|\| ! \is_callable([$batchPromise, 'then'])) {
300	4	throw new DataLoaderException(
301		self::class . ' must be constructed with a function which accepts ' .
302		'an array of keys and returns a Promise which resolves to an array of values ' .
303	4	\sprintf('the function returned %s.', \gettype($batchPromise))
304		);
305		}
306	24	}
307		}
308

lordthorzonus / php-dataloader

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DataLoader::scheduleDispatch() A

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