3 * Storage medium specific cache for storing items.
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
24 use Wikimedia\WaitConditionLoop
;
27 * Storage medium specific cache for storing items (e.g. redis, memcached, ...)
29 * This should not be used for proxy classes that simply wrap other cache instances
34 abstract class MediumSpecificBagOStuff
extends BagOStuff
{
35 /** @var array[] Lock tracking */
36 protected $locks = [];
37 /** @var int ERR_* class constant */
38 protected $lastError = self
::ERR_NONE
;
40 protected $keyspace = 'local';
41 /** @var int Seconds */
42 protected $syncTimeout;
43 /** @var int Bytes; chunk size of segmented cache values */
44 protected $segmentationSize;
45 /** @var int Bytes; maximum total size of a segmented cache value */
46 protected $segmentedValueMaxSize;
49 private $duplicateKeyLookups = [];
51 private $reportDupes = false;
53 private $dupeTrackScheduled = false;
55 /** @var callable[] */
56 protected $busyCallbacks = [];
58 /** @var string Component to use for key construction of blob segment keys */
59 const SEGMENT_COMPONENT
= 'segment';
62 * @see BagOStuff::__construct()
63 * Additional $params options include:
64 * - logger: Psr\Log\LoggerInterface instance
65 * - keyspace: Default keyspace for $this->makeKey()
66 * - reportDupes: Whether to emit warning log messages for all keys that were
67 * requested more than once (requires an asyncHandler).
68 * - syncTimeout: How long to wait with WRITE_SYNC in seconds.
69 * - segmentationSize: The chunk size, in bytes, of segmented values. The value should
70 * not exceed the maximum size of values in the storage backend, as configured by
71 * the site administrator.
72 * - segmentedValueMaxSize: The maximum total size, in bytes, of segmented values.
73 * This should be configured to a reasonable size give the site traffic and the
74 * amount of I/O between application and cache servers that the network can handle.
75 * @param array $params
77 public function __construct( array $params = [] ) {
78 parent
::__construct( $params );
80 if ( isset( $params['keyspace'] ) ) {
81 $this->keyspace
= $params['keyspace'];
84 if ( !empty( $params['reportDupes'] ) && is_callable( $this->asyncHandler
) ) {
85 $this->reportDupes
= true;
88 $this->syncTimeout
= $params['syncTimeout'] ??
3;
89 $this->segmentationSize
= $params['segmentationSize'] ??
8388608; // 8MiB
90 $this->segmentedValueMaxSize
= $params['segmentedValueMaxSize'] ??
67108864; // 64MiB
94 * Get an item with the given key
96 * If the key includes a deterministic input hash (e.g. the key can only have
97 * the correct value) or complete staleness checks are handled by the caller
98 * (e.g. nothing relies on the TTL), then the READ_VERIFIED flag should be set.
99 * This lets tiered backends know they can safely upgrade a cached value to
100 * higher tiers using standard TTLs.
103 * @param int $flags Bitfield of BagOStuff::READ_* constants [optional]
104 * @return mixed Returns false on failure or if the item does not exist
106 public function get( $key, $flags = 0 ) {
107 $this->trackDuplicateKeys( $key );
109 return $this->resolveSegments( $key, $this->doGet( $key, $flags ) );
113 * Track the number of times that a given key has been used.
116 private function trackDuplicateKeys( $key ) {
117 if ( !$this->reportDupes
) {
121 if ( !isset( $this->duplicateKeyLookups
[$key] ) ) {
122 // Track that we have seen this key. This N-1 counting style allows
123 // easy filtering with array_filter() later.
124 $this->duplicateKeyLookups
[$key] = 0;
126 $this->duplicateKeyLookups
[$key] +
= 1;
128 if ( $this->dupeTrackScheduled
=== false ) {
129 $this->dupeTrackScheduled
= true;
130 // Schedule a callback that logs keys processed more than once by get().
131 call_user_func( $this->asyncHandler
, function () {
132 $dups = array_filter( $this->duplicateKeyLookups
);
133 foreach ( $dups as $key => $count ) {
134 $this->logger
->warning(
135 'Duplicate get(): "{key}" fetched {count} times',
136 // Count is N-1 of the actual lookup count
137 [ 'key' => $key, 'count' => $count +
1, ]
147 * @param int $flags Bitfield of BagOStuff::READ_* constants [optional]
148 * @param mixed|null &$casToken Token to use for check-and-set comparisons
149 * @return mixed Returns false on failure or if the item does not exist
151 abstract protected function doGet( $key, $flags = 0, &$casToken = null );
157 * @param mixed $value
158 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
159 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
160 * @return bool Success
162 public function set( $key, $value, $exptime = 0, $flags = 0 ) {
163 list( $entry, $usable ) = $this->makeValueOrSegmentList( $key, $value, $exptime, $flags );
164 // Only when all segments (if any) are stored should the main key be changed
165 return $usable ?
$this->doSet( $key, $entry, $exptime, $flags ) : false;
172 * @param mixed $value
173 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
174 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
175 * @return bool Success
177 abstract protected function doSet( $key, $value, $exptime = 0, $flags = 0 );
182 * For large values written using WRITE_ALLOW_SEGMENTS, this only deletes the main
183 * segment list key unless WRITE_PRUNE_SEGMENTS is in the flags. While deleting the segment
184 * list key has the effect of functionally deleting the key, it leaves unused blobs in cache.
187 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
188 * @return bool True if the item was deleted or not found, false on failure
190 public function delete( $key, $flags = 0 ) {
191 if ( ( $flags & self
::WRITE_PRUNE_SEGMENTS
) != self
::WRITE_PRUNE_SEGMENTS
) {
192 return $this->doDelete( $key, $flags );
195 $mainValue = $this->doGet( $key, self
::READ_LATEST
);
196 if ( !$this->doDelete( $key, $flags ) ) {
200 if ( !SerializedValueContainer
::isSegmented( $mainValue ) ) {
201 return true; // no segments to delete
204 $orderedKeys = array_map(
205 function ( $segmentHash ) use ( $key ) {
206 return $this->makeGlobalKey( self
::SEGMENT_COMPONENT
, $key, $segmentHash );
208 $mainValue->{SerializedValueContainer
::SEGMENTED_HASHES
}
211 return $this->deleteMulti( $orderedKeys, $flags );
218 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
219 * @return bool True if the item was deleted or not found, false on failure
221 abstract protected function doDelete( $key, $flags = 0 );
223 public function add( $key, $value, $exptime = 0, $flags = 0 ) {
224 list( $entry, $usable ) = $this->makeValueOrSegmentList( $key, $value, $exptime, $flags );
225 // Only when all segments (if any) are stored should the main key be changed
226 return $usable ?
$this->doAdd( $key, $entry, $exptime, $flags ) : false;
230 * Insert an item if it does not already exist
233 * @param mixed $value
234 * @param int $exptime
235 * @param int $flags Bitfield of BagOStuff::WRITE_* constants (since 1.33)
236 * @return bool Success
238 abstract protected function doAdd( $key, $value, $exptime = 0, $flags = 0 );
241 * Merge changes into the existing cache value (possibly creating a new one)
243 * The callback function returns the new value given the current value
244 * (which will be false if not present), and takes the arguments:
245 * (this BagOStuff, cache key, current value, TTL).
246 * The TTL parameter is reference set to $exptime. It can be overriden in the callback.
247 * Nothing is stored nor deleted if the callback returns false.
250 * @param callable $callback Callback method to be executed
251 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
252 * @param int $attempts The amount of times to attempt a merge in case of failure
253 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
254 * @return bool Success
256 public function merge( $key, callable
$callback, $exptime = 0, $attempts = 10, $flags = 0 ) {
257 return $this->mergeViaCas( $key, $callback, $exptime, $attempts, $flags );
262 * @param callable $callback Callback method to be executed
263 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
264 * @param int $attempts The amount of times to attempt a merge in case of failure
265 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
266 * @return bool Success
267 * @see BagOStuff::merge()
269 final protected function mergeViaCas( $key, callable
$callback, $exptime, $attempts, $flags ) {
270 $attemptsLeft = $attempts;
272 $casToken = null; // passed by reference
273 // Get the old value and CAS token from cache
274 $this->clearLastError();
275 $currentValue = $this->resolveSegments(
277 $this->doGet( $key, self
::READ_LATEST
, $casToken )
279 if ( $this->getLastError() ) {
280 // Don't spam slow retries due to network problems (retry only on races)
281 $this->logger
->warning(
282 __METHOD__
. ' failed due to read I/O error on get() for {key}.',
289 // Derive the new value from the old value
290 $value = call_user_func( $callback, $this, $key, $currentValue, $exptime );
291 $keyWasNonexistant = ( $currentValue === false );
292 $valueMatchesOldValue = ( $value === $currentValue );
293 unset( $currentValue ); // free RAM in case the value is large
295 $this->clearLastError();
296 if ( $value === false ) {
297 $success = true; // do nothing
298 } elseif ( $valueMatchesOldValue && $attemptsLeft !== $attempts ) {
299 $success = true; // recently set by another thread to the same value
300 } elseif ( $keyWasNonexistant ) {
301 // Try to create the key, failing if it gets created in the meantime
302 $success = $this->add( $key, $value, $exptime, $flags );
304 // Try to update the key, failing if it gets changed in the meantime
305 $success = $this->cas( $casToken, $key, $value, $exptime, $flags );
307 if ( $this->getLastError() ) {
308 // Don't spam slow retries due to network problems (retry only on races)
309 $this->logger
->warning(
310 __METHOD__
. ' failed due to write I/O error for {key}.',
317 } while ( !$success && --$attemptsLeft );
323 * Check and set an item
325 * @param mixed $casToken
327 * @param mixed $value
328 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
329 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
330 * @return bool Success
332 protected function cas( $casToken, $key, $value, $exptime = 0, $flags = 0 ) {
333 if ( $casToken === null ) {
334 $this->logger
->warning(
335 __METHOD__
. ' got empty CAS token for {key}.',
339 return false; // caller may have meant to use add()?
342 list( $entry, $usable ) = $this->makeValueOrSegmentList( $key, $value, $exptime, $flags );
343 // Only when all segments (if any) are stored should the main key be changed
344 return $usable ?
$this->doCas( $casToken, $key, $entry, $exptime, $flags ) : false;
348 * Check and set an item
350 * @param mixed $casToken
352 * @param mixed $value
353 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
354 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
355 * @return bool Success
357 protected function doCas( $casToken, $key, $value, $exptime = 0, $flags = 0 ) {
358 // @TODO: the lock() call assumes that all other relavent sets() use one
359 if ( !$this->lock( $key, 0 ) ) {
360 return false; // non-blocking
363 $curCasToken = null; // passed by reference
364 $this->clearLastError();
365 $this->doGet( $key, self
::READ_LATEST
, $curCasToken );
366 if ( is_object( $curCasToken ) ) {
367 // Using === does not work with objects since it checks for instance identity
368 throw new UnexpectedValueException( "CAS token cannot be an object" );
370 if ( $this->getLastError() ) {
371 // Fail if the old CAS token could not be read
373 $this->logger
->warning(
374 __METHOD__
. ' failed due to write I/O error for {key}.',
377 } elseif ( $casToken === $curCasToken ) {
378 $success = $this->doSet( $key, $value, $exptime, $flags );
380 $success = false; // mismatched or failed
382 __METHOD__
. ' failed due to race condition for {key}.',
387 $this->unlock( $key );
393 * Change the expiration on a key if it exists
395 * If an expiry in the past is given then the key will immediately be expired
397 * For large values written using WRITE_ALLOW_SEGMENTS, this only changes the TTL of the
398 * main segment list key. While lowering the TTL of the segment list key has the effect of
399 * functionally lowering the TTL of the key, it might leave unused blobs in cache for longer.
400 * Raising the TTL of such keys is not effective, since the expiration of a single segment
401 * key effectively expires the entire value.
404 * @param int $exptime TTL or UNIX timestamp
405 * @param int $flags Bitfield of BagOStuff::WRITE_* constants (since 1.33)
406 * @return bool Success Returns false on failure or if the item does not exist
409 public function changeTTL( $key, $exptime = 0, $flags = 0 ) {
410 return $this->doChangeTTL( $key, $exptime, $flags );
415 * @param int $exptime
419 protected function doChangeTTL( $key, $exptime, $flags ) {
420 if ( !$this->lock( $key, 0 ) ) {
424 $expiry = $this->getExpirationAsTimestamp( $exptime );
425 $delete = ( $expiry != self
::TTL_INDEFINITE
&& $expiry < $this->getCurrentTime() );
427 // Use doGet() to avoid having to trigger resolveSegments()
428 $blob = $this->doGet( $key, self
::READ_LATEST
);
431 $ok = $this->doDelete( $key, $flags );
433 $ok = $this->doSet( $key, $blob, $exptime, $flags );
439 $this->unlock( $key );
445 * Acquire an advisory lock on a key string
447 * Note that if reentry is enabled, duplicate calls ignore $expiry
450 * @param int $timeout Lock wait timeout; 0 for non-blocking [optional]
451 * @param int $expiry Lock expiry [optional]; 1 day maximum
452 * @param string $rclass Allow reentry if set and the current lock used this value
453 * @return bool Success
455 public function lock( $key, $timeout = 6, $expiry = 6, $rclass = '' ) {
456 // Avoid deadlocks and allow lock reentry if specified
457 if ( isset( $this->locks
[$key] ) ) {
458 if ( $rclass != '' && $this->locks
[$key]['class'] === $rclass ) {
459 ++
$this->locks
[$key]['depth'];
467 $expiry = min( $expiry ?
: INF
, self
::TTL_DAY
);
468 $loop = new WaitConditionLoop(
469 function () use ( $key, $expiry, $fname ) {
470 $this->clearLastError();
471 if ( $this->add( "{$key}:lock", 1, $expiry ) ) {
472 return WaitConditionLoop
::CONDITION_REACHED
; // locked!
473 } elseif ( $this->getLastError() ) {
474 $this->logger
->warning(
475 $fname . ' failed due to I/O error for {key}.',
479 return WaitConditionLoop
::CONDITION_ABORTED
; // network partition?
482 return WaitConditionLoop
::CONDITION_CONTINUE
;
487 $code = $loop->invoke();
488 $locked = ( $code === $loop::CONDITION_REACHED
);
490 $this->locks
[$key] = [ 'class' => $rclass, 'depth' => 1 ];
491 } elseif ( $code === $loop::CONDITION_TIMED_OUT
) {
492 $this->logger
->warning(
493 "$fname failed due to timeout for {key}.",
494 [ 'key' => $key, 'timeout' => $timeout ]
502 * Release an advisory lock on a key string
505 * @return bool Success
507 public function unlock( $key ) {
508 if ( !isset( $this->locks
[$key] ) ) {
512 if ( --$this->locks
[$key]['depth'] <= 0 ) {
513 unset( $this->locks
[$key] );
515 $ok = $this->doDelete( "{$key}:lock" );
517 $this->logger
->warning(
518 __METHOD__
. ' failed to release lock for {key}.',
530 * Delete all objects expiring before a certain date.
531 * @param string|int $timestamp The reference date in MW or TS_UNIX format
532 * @param callable|null $progress Optional, a function which will be called
533 * regularly during long-running operations with the percentage progress
534 * as the first parameter. [optional]
535 * @param int $limit Maximum number of keys to delete [default: INF]
537 * @return bool Success; false if unimplemented
539 public function deleteObjectsExpiringBefore(
541 callable
$progress = null,
548 * Get an associative array containing the item for each of the keys that have items.
549 * @param string[] $keys List of keys; can be a map of (unused => key) for convenience
550 * @param int $flags Bitfield; supports READ_LATEST [optional]
551 * @return mixed[] Map of (key => value) for existing keys; preserves the order of $keys
553 public function getMulti( array $keys, $flags = 0 ) {
554 $foundByKey = $this->doGetMulti( $keys, $flags );
557 foreach ( $keys as $key ) {
558 // Resolve one blob at a time (avoids too much I/O at once)
559 if ( array_key_exists( $key, $foundByKey ) ) {
560 // A value should not appear in the key if a segment is missing
561 $value = $this->resolveSegments( $key, $foundByKey[$key] );
562 if ( $value !== false ) {
572 * Get an associative array containing the item for each of the keys that have items.
573 * @param string[] $keys List of keys
574 * @param int $flags Bitfield; supports READ_LATEST [optional]
575 * @return array Map of (key => value) for existing keys
577 protected function doGetMulti( array $keys, $flags = 0 ) {
579 foreach ( $keys as $key ) {
580 $val = $this->doGet( $key, $flags );
581 if ( $val !== false ) {
590 * Batch insertion/replace
592 * This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O
594 * @param mixed[] $data Map of (key => value)
595 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
596 * @param int $flags Bitfield of BagOStuff::WRITE_* constants (since 1.33)
597 * @return bool Success
600 public function setMulti( array $data, $exptime = 0, $flags = 0 ) {
601 if ( ( $flags & self
::WRITE_ALLOW_SEGMENTS
) === self
::WRITE_ALLOW_SEGMENTS
) {
602 throw new InvalidArgumentException( __METHOD__
. ' got WRITE_ALLOW_SEGMENTS' );
604 return $this->doSetMulti( $data, $exptime, $flags );
608 * @param mixed[] $data Map of (key => value)
609 * @param int $exptime Either an interval in seconds or a unix timestamp for expiry
610 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
611 * @return bool Success
613 protected function doSetMulti( array $data, $exptime = 0, $flags = 0 ) {
615 foreach ( $data as $key => $value ) {
616 $res = $this->doSet( $key, $value, $exptime, $flags ) && $res;
624 * This does not support WRITE_ALLOW_SEGMENTS to avoid excessive read I/O
626 * @param string[] $keys List of keys
627 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
628 * @return bool Success
631 public function deleteMulti( array $keys, $flags = 0 ) {
632 if ( ( $flags & self
::WRITE_ALLOW_SEGMENTS
) === self
::WRITE_ALLOW_SEGMENTS
) {
633 throw new InvalidArgumentException( __METHOD__
. ' got WRITE_ALLOW_SEGMENTS' );
635 return $this->doDeleteMulti( $keys, $flags );
639 * @param string[] $keys List of keys
640 * @param int $flags Bitfield of BagOStuff::WRITE_* constants
641 * @return bool Success
643 protected function doDeleteMulti( array $keys, $flags = 0 ) {
645 foreach ( $keys as $key ) {
646 $res = $this->doDelete( $key, $flags ) && $res;
652 * Change the expiration of multiple keys that exist
654 * @param string[] $keys List of keys
655 * @param int $exptime TTL or UNIX timestamp
656 * @param int $flags Bitfield of BagOStuff::WRITE_* constants (since 1.33)
657 * @return bool Success
658 * @see BagOStuff::changeTTL()
662 public function changeTTLMulti( array $keys, $exptime, $flags = 0 ) {
664 foreach ( $keys as $key ) {
665 $res = $this->doChangeTTL( $key, $exptime, $flags ) && $res;
672 * Decrease stored value of $key by $value while preserving its TTL
674 * @param int $value Value to subtract from $key (default: 1) [optional]
675 * @return int|bool New value or false on failure
677 public function decr( $key, $value = 1 ) {
678 return $this->incr( $key, -$value );
682 * Increase stored value of $key by $value while preserving its TTL
684 * This will create the key with value $init and TTL $ttl instead if not present
690 * @return int|bool New value or false on failure
693 public function incrWithInit( $key, $ttl, $value = 1, $init = 1 ) {
694 $this->clearLastError();
695 $newValue = $this->incr( $key, $value );
696 if ( $newValue === false && !$this->getLastError() ) {
697 // No key set; initialize
698 $newValue = $this->add( $key, (int)$init, $ttl ) ?
$init : false;
699 if ( $newValue === false && !$this->getLastError() ) {
700 // Raced out initializing; increment
701 $newValue = $this->incr( $key, $value );
709 * Get and reassemble the chunks of blob at the given key
712 * @param mixed $mainValue
713 * @return string|null|bool The combined string, false if missing, null on error
715 final protected function resolveSegments( $key, $mainValue ) {
716 if ( SerializedValueContainer
::isUnified( $mainValue ) ) {
717 return $this->unserialize( $mainValue->{SerializedValueContainer
::UNIFIED_DATA
} );
720 if ( SerializedValueContainer
::isSegmented( $mainValue ) ) {
721 $orderedKeys = array_map(
722 function ( $segmentHash ) use ( $key ) {
723 return $this->makeGlobalKey( self
::SEGMENT_COMPONENT
, $key, $segmentHash );
725 $mainValue->{SerializedValueContainer
::SEGMENTED_HASHES
}
728 $segmentsByKey = $this->doGetMulti( $orderedKeys );
731 foreach ( $orderedKeys as $segmentKey ) {
732 if ( isset( $segmentsByKey[$segmentKey] ) ) {
733 $parts[] = $segmentsByKey[$segmentKey];
735 return false; // missing segment
739 return $this->unserialize( implode( '', $parts ) );
746 * Get the "last error" registered; clearLastError() should be called manually
747 * @return int ERR_* constant for the "last error" registry
750 public function getLastError() {
751 return $this->lastError
;
755 * Clear the "last error" registry
758 public function clearLastError() {
759 $this->lastError
= self
::ERR_NONE
;
763 * Set the "last error" registry
764 * @param int $err ERR_* constant
767 protected function setLastError( $err ) {
768 $this->lastError
= $err;
772 * Let a callback be run to avoid wasting time on special blocking calls
774 * The callbacks may or may not be called ever, in any particular order.
775 * They are likely to be invoked when something WRITE_SYNC is used used.
776 * They should follow a caching pattern as shown below, so that any code
777 * using the work will get it's result no matter what happens.
780 * $workCallback = function () use ( &$result ) {
788 * @param callable $workCallback
791 final public function addBusyCallback( callable
$workCallback ) {
792 $this->busyCallbacks
[] = $workCallback;
796 * Determine the entry (inline or segment list) to store under a key to save the value
799 * @param mixed $value
800 * @param int $exptime
802 * @return array (inline value or segment list, whether the entry is usable)
805 final protected function makeValueOrSegmentList( $key, $value, $exptime, $flags ) {
810 ( $flags & self
::WRITE_ALLOW_SEGMENTS
) === self
::WRITE_ALLOW_SEGMENTS
&&
811 !is_int( $value ) && // avoid breaking incr()/decr()
812 is_finite( $this->segmentationSize
)
814 $segmentSize = $this->segmentationSize
;
815 $maxTotalSize = $this->segmentedValueMaxSize
;
817 $serialized = $this->serialize( $value );
818 $size = strlen( $serialized );
819 if ( $size > $maxTotalSize ) {
820 $this->logger
->warning(
821 "Value for {key} exceeds $maxTotalSize bytes; cannot segment.",
824 } elseif ( $size <= $segmentSize ) {
825 // The serialized value was already computed, so just use it inline
826 $entry = SerializedValueContainer
::newUnified( $serialized );
828 // Split the serialized value into chunks and store them at different keys
831 $count = intdiv( $size, $segmentSize ) +
( ( $size %
$segmentSize ) ?
1 : 0 );
832 for ( $i = 0; $i < $count; ++
$i ) {
833 $segment = substr( $serialized, $i * $segmentSize, $segmentSize );
834 $hash = sha1( $segment );
835 $chunkKey = $this->makeGlobalKey( self
::SEGMENT_COMPONENT
, $key, $hash );
836 $chunksByKey[$chunkKey] = $segment;
837 $segmentHashes[] = $hash;
839 $flags &= ~self
::WRITE_ALLOW_SEGMENTS
; // sanity
840 $usable = $this->setMulti( $chunksByKey, $exptime, $flags );
841 $entry = SerializedValueContainer
::newSegmented( $segmentHashes );
845 return [ $entry, $usable ];
849 * @param int|float $exptime
850 * @return bool Whether the expiry is non-infinite, and, negative or not a UNIX timestamp
853 final protected function isRelativeExpiration( $exptime ) {
854 return ( $exptime !== self
::TTL_INDEFINITE
&& $exptime < ( 10 * self
::TTL_YEAR
) );
858 * Convert an optionally relative timestamp to an absolute time
860 * The input value will be cast to an integer and interpreted as follows:
861 * - zero: no expiry; return zero (e.g. TTL_INDEFINITE)
862 * - negative: relative TTL; return UNIX timestamp offset by this value
863 * - positive (< 10 years): relative TTL; return UNIX timestamp offset by this value
864 * - positive (>= 10 years): absolute UNIX timestamp; return this value
866 * @param int $exptime
867 * @return int Expiration timestamp or TTL_INDEFINITE for indefinite
870 final protected function getExpirationAsTimestamp( $exptime ) {
871 if ( $exptime == self
::TTL_INDEFINITE
) {
875 return $this->isRelativeExpiration( $exptime )
876 ?
intval( $this->getCurrentTime() +
$exptime )
881 * Convert an optionally absolute expiry time to a relative time. If an
882 * absolute time is specified which is in the past, use a short expiry time.
884 * The input value will be cast to an integer and interpreted as follows:
885 * - zero: no expiry; return zero (e.g. TTL_INDEFINITE)
886 * - negative: relative TTL; return a short expiry time (1 second)
887 * - positive (< 10 years): relative TTL; return this value
888 * - positive (>= 10 years): absolute UNIX timestamp; return offset to current time
890 * @param int $exptime
891 * @return int Relative TTL or TTL_INDEFINITE for indefinite
894 final protected function getExpirationAsTTL( $exptime ) {
895 if ( $exptime == self
::TTL_INDEFINITE
) {
899 return $this->isRelativeExpiration( $exptime )
901 : (int)max( $exptime - $this->getCurrentTime(), 1 );
905 * Check if a value is an integer
907 * @param mixed $value
910 final protected function isInteger( $value ) {
911 if ( is_int( $value ) ) {
913 } elseif ( !is_string( $value ) ) {
917 $integer = (int)$value;
919 return ( $value === (string)$integer );
923 * Construct a cache key.
925 * @param string $keyspace
927 * @return string Colon-delimited list of $keyspace followed by escaped components of $args
930 public function makeKeyInternal( $keyspace, $args ) {
932 foreach ( $args as $arg ) {
933 $key .= ':' . str_replace( ':', '%3A', $arg );
935 return strtr( $key, ' ', '_' );
939 * Make a global cache key.
941 * @param string $class Key class
942 * @param string ...$components Key components (starting with a key collection name)
943 * @return string Colon-delimited list of $keyspace followed by escaped components
946 public function makeGlobalKey( $class, ...$components ) {
947 return $this->makeKeyInternal( 'global', func_get_args() );
951 * Make a cache key, scoped to this instance's keyspace.
953 * @param string $class Key class
954 * @param string ...$components Key components (starting with a key collection name)
955 * @return string Colon-delimited list of $keyspace followed by escaped components
958 public function makeKey( $class, ...$components ) {
959 return $this->makeKeyInternal( $this->keyspace
, func_get_args() );
963 * @param int $flag ATTR_* class constant
964 * @return int QOS_* class constant
967 public function getQoS( $flag ) {
968 return $this->attrMap
[$flag] ?? self
::QOS_UNKNOWN
;
972 * @return int|float The chunk size, in bytes, of segmented objects (INF for no limit)
975 public function getSegmentationSize() {
976 return $this->segmentationSize
;
980 * @return int|float Maximum total segmented object size in bytes (INF for no limit)
983 public function getSegmentedValueMaxSize() {
984 return $this->segmentedValueMaxSize
;
988 * @param mixed $value
989 * @return string|int String/integer representation
990 * @note Special handling is usually needed for integers so incr()/decr() work
992 protected function serialize( $value ) {
993 return is_int( $value ) ?
$value : serialize( $value );
997 * @param string|int $value
998 * @return mixed Original value or false on error
999 * @note Special handling is usually needed for integers so incr()/decr() work
1001 protected function unserialize( $value ) {
1002 return $this->isInteger( $value ) ?
(int)$value : unserialize( $value );
1006 * @param string $text
1008 protected function debug( $text ) {
1009 if ( $this->debugMode
) {
1010 $this->logger
->debug( "{class} debug: $text", [ 'class' => static::class ] );