1MCE::Shared::Cache(3) User Contributed Perl DocumentationMCE::Shared::Cache(3)
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6 MCE::Shared::Cache - A hybrid LRU-plain cache helper class
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9 This document describes MCE::Shared::Cache version 1.886
10
12 A cache helper class for use as a standalone or managed by MCE::Shared.
13 This module implements a least-recently used (LRU) cache with its
15 origin based on MCE::Shared::Ordhash, for its performance and low-
16 memory characteristics. It is both a LRU and plain implementation. LRU
17 logic is applied to new items and subsequent updates. A fetch however,
18 involves LRU reorder only if the item is found in the lower section of
19 the cache. This equates to extra performance for the upper section as
20 fetch behaves similarly to accessing a plain cache. Upon reaching its
21 size restriction, it prunes items from the bottom of the cache.
22 The 50% LRU-mode (bottom section), 50% plain-mode (upper-section)
24 applies to fetches only.
25
27 # non-shared or local construction for use by a single process
28 use MCE::Shared::Cache;
30 my $ca;
32 $ca = MCE::Shared::Cache->new(); # max_keys => undef, max_age => undef
34 $ca = MCE::Shared::Cache->new( { max_keys => 500 }, @pairs );
35 $ca = MCE::Shared::Cache->new( max_keys => "unlimited", max_age => "never" );
37 $ca = MCE::Shared::Cache->new( max_keys => undef, max_age => undef ); # ditto
38 $ca = MCE::Shared::Cache->new( max_keys => 500, max_age => "1 hour" );
39 $ca = MCE::Shared::Cache->new( max_keys => "4 KiB" ); # 4*1024
40 $ca = MCE::Shared::Cache->new( max_keys => "1 MiB" ); # 1*1024*1024
41 $ca = MCE::Shared::Cache->new( max_age => "43200 seconds" );
43 $ca = MCE::Shared::Cache->new( max_age => 43200 ); # ditto
44 $ca = MCE::Shared::Cache->new( max_age => "720 minutes" );
45 $ca = MCE::Shared::Cache->new( max_age => "12 hours" );
46 $ca = MCE::Shared::Cache->new( max_age => "0.5 days" );
47 $ca = MCE::Shared::Cache->new( max_age => "1 week" );
48 $ca = MCE::Shared::Cache->new( max_age => undef ); # no expiration
49 $ca = MCE::Shared::Cache->new( max_age => 0 ); # now
50 # construction for sharing with other threads and processes
52 use MCE::Shared;
54 my $ca;
56 $ca = MCE::Shared->cache(); # max_keys => undef, max_age => undef
58 $ca = MCE::Shared->cache( { max_keys => 500 }, @pairs );
59 $ca = MCE::Shared->cache( max_keys => "unlimited", max_age => "never" );
61 $ca = MCE::Shared->cache( max_keys => undef, max_age => undef ); # ditto
62 $ca = MCE::Shared->cache( max_keys => 500, max_age => "1 hour" );
63 $ca = MCE::Shared->cache( max_keys => "4 KiB" ); # 4*1024
64 $ca = MCE::Shared->cache( max_keys => "1 MiB" ); # 1*1024*1024
65 $ca = MCE::Shared->cache( max_age => "43200 seconds" );
67 $ca = MCE::Shared->cache( max_age => 43200 ); # ditto
68 $ca = MCE::Shared->cache( max_age => "720 minutes" );
69 $ca = MCE::Shared->cache( max_age => "12 hours" );
70 $ca = MCE::Shared->cache( max_age => "0.5 days" );
71 $ca = MCE::Shared->cache( max_age => "1 week" );
72 $ca = MCE::Shared->cache( max_age => undef ); # no expiration
73 $ca = MCE::Shared->cache( max_age => 0 ); # now
74 # hash-like dereferencing
76 my $val = $ca->{$key};
78 $ca->{$key} = $val;
79 %{$ca} = ();
81 # OO interface
83 if ( !defined ( $val = $ca->get("some_key") ) ) {
85 $val = $ca->set( some_key => "some_value" );
86 }
87 $val = $ca->set( $key, $val );
89 $ret = $ca->setnx( $key, $val ); # set only if the key exists
90 $val = $ca->get( $key );
91 $val = $ca->delete( $key ); # del is an alias for delete
92 $bool = $ca->exists( $key );
93 void = $ca->clear();
94 $len = $ca->len(); # scalar keys %{ $ca }
95 $len = $ca->len( $key ); # length $ca->{ $key }
96 $iter = $ca->iterator( @keys ); # ($key, $val) = $iter->()
98 @keys = $ca->keys( @keys ); # @keys is optional
99 %pairs = $ca->pairs( @keys );
100 @vals = $ca->values( @keys ); # vals is an alias for values
101 $len = $ca->assign( $key/$val pairs ); # equivalent to ->clear, ->mset
103 $cnt = $ca->mdel( @keys );
104 @vals = $ca->mget( @keys );
105 $bool = $ca->mexists( @keys ); # true if all keys exists
106 $len = $ca->mset( $key/$val pairs ); # merge is an alias for mset
107 # included, sugar methods without having to call set/get explicitly
109 $len = $ca->append( $key, $string ); # $val .= $string
111 $val = $ca->decr( $key ); # --$val
112 $val = $ca->decrby( $key, $number ); # $val -= $number
113 $val = $ca->getdecr( $key ); # $val--
114 $val = $ca->getincr( $key ); # $val++
115 $val = $ca->incr( $key ); # ++$val
116 $val = $ca->incrby( $key, $number ); # $val += $number
117 $old = $ca->getset( $key, $new ); # $o = $v, $v = $n, $o
118 # pipeline, provides atomicity for shared objects, MCE::Shared v1.09+
120 @vals = $ca->pipeline( # ( "a_a", "b_b", "c_c" )
122 [ "set", foo => "a_a" ],
123 [ "set", bar => "b_b" ],
124 [ "set", baz => "c_c" ],
125 [ "mget", qw/ foo bar baz / ]
126 );
127 For normal hash behavior, the TIE interface is supported.
129 # non-shared or local construction for use by a single process
131 use MCE::Shared::Cache;
133 tie my %ca, "MCE::Shared::Cache", max_keys => undef, max_age => undef;
135 tie my %ca, "MCE::Shared::Cache", max_keys => 500, max_age => "1 hour";
136 tie my %ca, "MCE::Shared::Cache", { max_keys => 500 }, @pairs;
137 # construction for sharing with other threads and processes
139 # one option is needed minimally to know to use MCE::Shared::Cache
140 use MCE::Shared;
142 tie my %ca, "MCE::Shared", max_keys => undef, max_age => undef;
144 tie my %ca, "MCE::Shared", max_keys => 500, max_age => "1 hour";
145 tie my %ca, "MCE::Shared", { max_keys => 500 }, @pairs;
146 # usage
148 my $val;
150 if ( !defined ( $val = $ca{some_key} ) ) {
152 $val = $ca{some_key} = "some_value";
153 }
154 $ca{some_key} = 0;
156 tied(%ca)->incrby("some_key", 20);
158 tied(%ca)->incrby(some_key => 20);
159
161 Several methods take a query string for an argument. The format of the
162 string is described below. In the context of sharing, the query
163 mechanism is beneficial for the shared-manager process. It is able to
164 perform the query where the data resides versus the client-process grep
165 locally involving lots of IPC.
166 o Basic demonstration
168 @keys = $ca->keys( "query string given here" );
170 @keys = $ca->keys( "val =~ /pattern/" );
171 o Supported operators: =~ !~ eq ne lt le gt ge == != < <= > >=
173 o Multiple expressions delimited by :AND or :OR, mixed case allowed
174 "key eq 'some key' :or (val > 5 :and val < 9)"
176 "key eq some key :or (val > 5 :and val < 9)"
177 "key =~ /pattern/i :And val =~ /pattern/i"
178 "val eq foo baz :OR key !~ /pattern/i"
179 * key matches on keys in the cache
181 * likewise, val matches on values
182 o Quoting is optional inside the string
184 "key =~ /pattern/i :AND val eq 'foo bar'" # val eq "foo bar"
186 "key =~ /pattern/i :AND val eq foo bar" # val eq "foo bar"
187 Examples.
189 # search capability key/val: =~ !~ eq ne lt le gt ge == != < <= > >=
191 # key/val means to match against actual key/val respectively
192 @keys = $ca->keys( "key eq 'some key' :or (val > 5 :and val < 9)" );
194 @keys = $ca->keys( "key eq some key :or (val > 5 :and val < 9)" );
195 @keys = $ca->keys( "key =~ /$pattern/i" );
197 @keys = $ca->keys( "key !~ /$pattern/i" );
198 @keys = $ca->keys( "val =~ /$pattern/i" );
199 @keys = $ca->keys( "val !~ /$pattern/i" );
200 %pairs = $ca->pairs( "key == $number" );
202 %pairs = $ca->pairs( "key != $number :and val > 100" );
203 %pairs = $ca->pairs( "key < $number :or key > $number" );
204 %pairs = $ca->pairs( "val <= $number" );
205 %pairs = $ca->pairs( "val > $number" );
206 %pairs = $ca->pairs( "val >= $number" );
207 @vals = $ca->vals( "key eq $string" );
209 @vals = $ca->vals( "key ne $string with space" );
210 @vals = $ca->vals( "key lt $string :or val =~ /$pat1|$pat2/" );
211 @vals = $ca->vals( "val le $string :and val eq 'foo bar'" );
212 @vals = $ca->vals( "val le $string :and val eq foo bar" );
213 @vals = $ca->vals( "val gt $string" );
214 @vals = $ca->vals( "val ge $string" );
215
217 This module involves TIE when accessing the object via hash-like
218 behavior. Both non-shared and shared instances are impacted if doing
219 so. Although likely fast enough for many use cases, the OO interface is
220 recommended for best performance.
221 Accessing an item is likely to involve moving its key to the top of the
223 cache. Various methods described below state with "Reorder: Yes" or
224 "Reorder: No" as an indication.
225 The methods "keys", "pairs", and "values" return the most frequently
227 accessed items from the upper section of the cache first before the
228 lower section. Returned values may not be ordered as expected. This
229 abnormally is normal for this hybrid LRU-plain implementation. It comes
230 from fetches not involving LRU movement on keys residing in the upper
231 section of the cache.
232 When "max_age" is set, accessing an item which has expired will behave
234 similarly to a non-existing item.
235 MCE::Shared::Cache->new ( { options }, key, value [, key, value, ... ] )
237 MCE::Shared->cache ( { options }, key, value [, key, value, ... ] )
238 Constructs a new object.
239 # non-shared or local construction for use by a single process
241 use MCE::Shared::Cache;
243 $ca = MCE::Shared::Cache->new(); # max_keys => undef, max_age => undef
245 $ca = MCE::Shared::Cache->new( { max_keys => 500 }, @pairs );
246 $ca = MCE::Shared::Cache->new( max_keys => "unlimited", max_age => "never" );
248 $ca = MCE::Shared::Cache->new( max_keys => undef, max_age => undef ); # ditto
249 $ca = MCE::Shared::Cache->new( max_keys => 500, max_age => "1 hour" );
250 $ca = MCE::Shared::Cache->new( max_keys => "4 KiB" ); # 4*1024
251 $ca = MCE::Shared::Cache->new( max_keys => "1 MiB" ); # 1*1024*1024
252 $ca = MCE::Shared::Cache->new( max_age => "43200 seconds" );
254 $ca = MCE::Shared::Cache->new( max_age => 43200 ); # ditto
255 $ca = MCE::Shared::Cache->new( max_age => "720 minutes" );
256 $ca = MCE::Shared::Cache->new( max_age => "12 hours" );
257 $ca = MCE::Shared::Cache->new( max_age => "0.5 days" );
258 $ca = MCE::Shared::Cache->new( max_age => "1 week" );
259 $ca = MCE::Shared::Cache->new( max_age => undef ); # no expiration
260 $ca = MCE::Shared::Cache->new( max_age => 0 ); # now
261 $ca->assign( @pairs );
263 # construction for sharing with other threads and processes
265 use MCE::Shared;
267 $ca = MCE::Shared->cache(); # max_keys => undef, max_age => undef
269 $ca = MCE::Shared->cache( { max_keys => 500 }, @pairs );
270 $ca = MCE::Shared->cache( max_keys => "unlimited", max_age => "never" );
272 $ca = MCE::Shared->cache( max_keys => undef, max_age => undef ); # ditto
273 $ca = MCE::Shared->cache( max_keys => 500, max_age => "1 hour" );
274 $ca = MCE::Shared->cache( max_keys => "4 KiB" ); # 4*1024
275 $ca = MCE::Shared->cache( max_keys => "1 MiB" ); # 1*1024*1024
276 $ca = MCE::Shared->cache( max_age => "43200 seconds" );
278 $ca = MCE::Shared->cache( max_age => 43200 ); # ditto
279 $ca = MCE::Shared->cache( max_age => "720 minutes" );
280 $ca = MCE::Shared->cache( max_age => "12 hours" );
281 $ca = MCE::Shared->cache( max_age => "0.5 days" );
282 $ca = MCE::Shared->cache( max_age => "1 week" );
283 $ca = MCE::Shared->cache( max_age => undef ); # no expiration
284 $ca = MCE::Shared->cache( max_age => 0 ); # now
285 $ca->assign( @pairs );
287 Reorder: Yes, when given key-value pairs contain duplicate keys
289 assign ( key, value [, key, value, ... ] )
291 Clears the cache, then sets multiple key-value pairs and returns the
292 number of keys stored in the cache. This is equivalent to "clear",
293 "mset".
294 $len = $ca->assign( "key1" => "val1", "key2" => "val2" );
296 Reorder: Yes, when given key-value pairs contain duplicate keys
298 clear
300 Removes all key-value pairs from the cache.
301 $ca->clear;
303 %{$ca} = ();
304 delete ( key )
306 Deletes and returns the value by given key or "undef" if the key does
307 not exists in the cache.
308 $val = $ca->delete( "some_key" );
310 $val = delete $ca->{ "some_key" };
311 del
313 "del" is an alias for "delete".
314 exists ( key )
316 Determines if a key exists in the cache.
317 if ( $ca->exists( "some_key" ) ) { ... }
319 if ( exists $ca->{ "some_key" } ) { ... }
320 Reorder: No
322 get ( key )
324 Gets the value of a cache key or "undef" if the key does not exists.
325 LRU reordering occurs only if the key is found in the lower section of
326 the cache. See "peek" to not promote the key internally to the top of
327 the list.
328 $val = $ca->get( "some_key" );
330 $val = $ca->{ "some_key" };
331 Reorder: Yes
333 iterator ( key [, key, ... ] )
335 When "max_age" is set, prunes any expired keys at the head of the list.
336 Returns a code reference for iterating a list of key-value pairs stored
338 in the cache when no arguments are given. Otherwise, returns a code
339 reference for iterating the given keys in the same order. Keys that do
340 not exist will have the "undef" value.
341 The list of keys to return is set when the closure is constructed.
343 Later keys added to the hash are not included. Subsequently, the
344 "undef" value is returned for deleted keys.
345 $iter = $ca->iterator;
347 $iter = $ca->iterator( "key1", "key2" );
348 while ( my ( $key, $val ) = $iter->() ) {
350 ...
351 }
352 Reorder: No
354 iterator ( "query string" )
356 When "max_age" is set, prunes any expired keys at the head of the list.
357 Returns a code reference for iterating a list of key-value pairs that
359 match the given criteria. It returns an empty list if the search found
360 nothing. The syntax for the "query string" is described above.
361 $iter = $ca->iterator( "val eq some_value" );
363 $iter = $ca->iterator( "key eq some_key :AND val =~ /sun|moon|air|wind/" );
364 $iter = $ca->iterator( "val eq sun :OR val eq moon :OR val eq foo" );
365 $iter = $ca->iterator( "key =~ /$pattern/" );
366 while ( my ( $key, $val ) = $iter->() ) {
368 ...
369 }
370 Reorder: No
372 keys ( key [, key, ... ] )
374 When "max_age" is set, prunes any expired keys at the head of the list.
375 Returns all keys in the cache by most frequently accessed when no
377 arguments are given. Otherwise, returns the given keys in the same
378 order. Keys that do not exist will have the "undef" value. In scalar
379 context, returns the size of the cache.
380 @keys = $ca->keys;
382 @keys = $ca->keys( "key1", "key2" );
383 $len = $ca->keys;
384 Reorder: No
386 keys ( "query string" )
388 When "max_age" is set, prunes any expired keys at the head of the list.
389 Returns only keys that match the given criteria. It returns an empty
391 list if the search found nothing. The syntax for the "query string" is
392 described above. In scalar context, returns the size of the resulting
393 list.
394 @keys = $ca->keys( "val eq some_value" );
396 @keys = $ca->keys( "key eq some_key :AND val =~ /sun|moon|air|wind/" );
397 @keys = $ca->keys( "val eq sun :OR val eq moon :OR val eq foo" );
398 $len = $ca->keys( "key =~ /$pattern/" );
399 Reorder: No
401 len ( key )
403 When "max_age" is set, prunes any expired keys at the head of the list.
404 Returns the size of the cache when no arguments are given. For the
406 given key, returns the length of the value stored at key or the "undef"
407 value if the key does not exists.
408 $size = $ca->len;
410 $len = $ca->len( "key1" );
411 $len = length $ca->{ "key1" };
412 Reorder: Yes, only when key is given
414 max_age ( [ secs ] )
416 Returns the maximum age set on the cache or "never" if not defined
417 internally. It sets the default expiry time when seconds is given.
418 $age = $ca->max_age;
420 $ca->max_age( "43200 seconds" );
422 $ca->max_age( 43200 ); # ditto
423 $ca->max_age( "720 minutes" );
424 $ca->max_age( "12 hours" );
425 $ca->max_age( "0.5 days" );
426 $ca->max_age( "1 week" );
427 $ca->max_age( undef ); # no expiration
428 $ca->max_age( 0 ); # now
429 max_keys ( [ size ] )
431 Returns the size limit set on the cache or "unlimited" if not defined
432 internally. When size is given, it adjusts the cache accordingly to the
433 new size by pruning the head of the list if necessary.
434 $size = $ca->max_keys;
436 $ca->max_keys( undef ); # unlimited
438 $ca->max_keys( "4 KiB" ); # 4*1024
439 $ca->max_keys( "1 MiB" ); # 1*1024*1024
440 $ca->max_keys( 500 );
441 mdel ( key [, key, ... ] )
443 Deletes one or more keys in the cache and returns the number of keys
444 deleted. A given key which does not exist in the cache is not counted.
445 $cnt = $ca->mdel( "key1", "key2" );
447 mexists ( key [, key, ... ] )
449 Returns a true value if all given keys exists in the cache. A false
450 value is returned otherwise.
451 if ( $ca->mexists( "key1", "key2" ) ) { ... }
453 Reorder: No
455 mget ( key [, key, ... ] )
457 Gets the values of all given keys. It returns "undef" for keys which do
458 not exists in the cache.
459 ( $val1, $val2 ) = $ca->mget( "key1", "key2" );
461 Reorder: Yes
463 mset ( key, value [, key, value, ... ] )
465 Sets multiple key-value pairs in a cache and returns the number of keys
466 stored in the cache.
467 $len = $ca->mset( "key1" => "val1", "key2" => "val2" );
469 Reorder: Yes
471 merge
473 "merge" is an alias for "mset".
474 pairs ( key [, key, ... ] )
476 When "max_age" is set, prunes any expired keys at the head of the list.
477 Returns key-value pairs in the cache by most frequently accessed when
479 no arguments are given. Otherwise, returns key-value pairs for the
480 given keys in the same order. Keys that do not exist will have the
481 "undef" value. In scalar context, returns the size of the cache.
482 @pairs = $ca->pairs;
484 @pairs = $ca->pairs( "key1", "key2" );
485 $len = $ca->pairs;
486 Reorder: No
488 pairs ( "query string" )
490 When "max_age" is set, prunes any expired keys at the head of the list.
491 Returns only key-value pairs that match the given criteria. It returns
493 an empty list if the search found nothing. The syntax for the "query
494 string" is described above. In scalar context, returns the size of the
495 resulting list.
496 @pairs = $ca->pairs( "val eq some_value" );
498 @pairs = $ca->pairs( "key eq some_key :AND val =~ /sun|moon|air|wind/" );
499 @pairs = $ca->pairs( "val eq sun :OR val eq moon :OR val eq foo" );
500 $len = $ca->pairs( "key =~ /$pattern/" );
501 Reorder: No
503 peek ( key )
505 Same as "get" without changing the order of the keys. Gets the value of
506 a cache key or "undef" if the key does not exists.
507 $val = $ca->get( "some_key" );
509 $val = $ca->{ "some_key" };
510 Reorder: No
512 pipeline ( [ func1, @args ], [ func2, @args ], ... )
514 Combines multiple commands for the object to be processed serially. For
515 shared objects, the call is made atomically due to single IPC to the
516 shared-manager process. The "pipeline" method is fully
517 "wantarray"-aware and receives a list of commands and their arguments.
518 In scalar or list context, it returns data from the last command in the
519 pipeline.
520 @vals = $ca->pipeline( # ( "a_a", "b_b", "c_c" )
522 [ "set", foo => "a_a" ],
523 [ "set", bar => "b_b" ],
524 [ "set", baz => "c_c" ],
525 [ "mget", qw/ foo bar baz / ]
526 );
527 $len = $ca->pipeline( # 3, same as $ca->len
529 [ "set", foo => "i_i" ],
530 [ "set", bar => "j_j" ],
531 [ "set", baz => "k_k" ],
532 [ "len" ]
533 );
534 $ca->pipeline(
536 [ "set", foo => "m_m" ],
537 [ "set", bar => "n_n" ],
538 [ "set", baz => "o_o" ]
539 );
540 Reorder: Very likely, see API on given method
542 pipeline_ex ( [ func1, @args ], [ func2, @args ], ... )
544 Same as "pipeline", but returns data for every command in the pipeline.
545 @vals = $ca->pipeline_ex( # ( "a_a", "b_b", "c_c" )
547 [ "set", foo => "a_a" ],
548 [ "set", bar => "b_b" ],
549 [ "set", baz => "c_c" ]
550 );
551 Reorder: Very likely, see API on given command
553 purge ( )
555 Remove all tombstones and expired data from the cache.
556 $ca->purge;
558 remove
560 "remove" is an alias for "delete".
561 set ( key, value [, expires_in ] )
563 Sets the value of the given cache key and returns its new value.
564 Optionally in v1.839 and later releases, give the number of seconds
565 before the key is expired.
566 $val = $ca->set( "key", "value" );
568 $val = $ca->{ "key" } = "value";
569 $val = $ca->set( "key", "value", 3600 ); # or "60 minutes"
571 $val = $ca->set( "key", "value", undef ); # or "never"
572 $val = $ca->set( "key", "value", 0 ); # or "now"
573 $val = $ca->set( "key", "value", "2 seconds" ); # or "2s"
575 $val = $ca->set( "key", "value", "2 minutes" ); # or "2m"
576 $val = $ca->set( "key", "value", "2 hours" ); # or "2h"
577 $val = $ca->set( "key", "value", "2 days" ); # or "2d"
578 $val = $ca->set( "key", "value", "2 weeks" ); # or "2w"
579 Reorder: Yes
581 setnx ( key, value [, expires_in ] )
583 Sets the value of a hash key, only if the key does not exist. Returns a
584 1 for new key or 0 if the key already exists and no operation was
585 performed. Optionally, give the number of seconds before the key is
586 expired.
587 $ret = $ca->setnx( "key", "value" );
589 Current API available since 1.872.
591 Reorder: Yes
593 values ( key [, key, ... ] )
595 When "max_age" is set, prunes any expired keys at the head of the list.
596 Returns all values in the cache by most frequently accessed when no
598 arguments are given. Otherwise, returns values for the given keys in
599 the same order. Keys that do not exist will have the "undef" value. In
600 scalar context, returns the size of the cache.
601 @vals = $ca->values;
603 @vals = $ca->values( "key1", "key2" );
604 $len = $ca->values;
605 Reorder: No
607 values ( "query string" )
609 When "max_age" is set, prunes any expired keys at the head of the list.
610 Returns only values that match the given criteria. It returns an empty
612 list if the search found nothing. The syntax for the "query string" is
613 described above. In scalar context, returns the size of the resulting
614 list.
615 @vals = $ca->values( "val eq some_value" );
617 @vals = $ca->values( "key eq some_key :AND val =~ /sun|moon|air|wind/" );
618 @vals = $ca->values( "val eq sun :OR val eq moon :OR val eq foo" );
619 $len = $ca->values( "key =~ /$pattern/" );
620 Reorder: No
622 vals
624 "vals" is an alias for "values".
625
627 This module is equipped with sugar methods to not have to call "set"
628 and "get" explicitly. In shared context, the benefit is atomicity and
629 reduction in inter-process communication.
630 The API resembles a subset of the Redis primitives
632 <https://redis.io/commands#strings> with key representing the cache
633 key.
634 Optionally in v1.839 and later releases, give the number of seconds
636 before the key is expired, similarly to "set".
637 append ( key, string [, expires_in ] )
639 Appends a value to a key and returns its new length.
640 $len = $ca->append( $key, "foo" );
642 Reorder: Yes
644 decr ( key [, expires_in ] )
646 Decrements the value of a key by one and returns its new value.
647 $num = $ca->decr( $key );
649 Reorder: Yes
651 decrby ( key, number [, expires_in ] )
653 Decrements the value of a key by the given number and returns its new
654 value.
655 $num = $ca->decrby( $key, 2 );
657 Reorder: Yes
659 getdecr ( key [, expires_in ] )
661 Decrements the value of a key by one and returns its old value.
662 $old = $ca->getdecr( $key );
664 Reorder: Yes
666 getincr ( key [, expires_in ] )
668 Increments the value of a key by one and returns its old value.
669 $old = $ca->getincr( $key );
671 Reorder: Yes
673 getset ( key, value [, expires_in ] )
675 Sets the value of a key and returns its old value.
676 $old = $ca->getset( $key, "baz" );
678 Reorder: Yes
680 incr ( key [, expires_in ] )
682 Increments the value of a key by one and returns its new value.
683 $num = $ca->incr( $key );
685 Reorder: Yes
687 incrby ( key, number [, expires_in ] )
689 Increments the value of a key by the given number and returns its new
690 value.
691 $num = $ca->incrby( $key, 2 );
693 Reorder: Yes
695
697 Internal "Sereal" freeze-thaw hooks for exporting shared-cache object.
698 FREEZE
700 THAW
701 Internal "Storable" freeze-thaw hooks for exporting shared-cache
703 object.
704 STORABLE_freeze
706 STORABLE_thaw
707
709 One might want to benchmark this module. If yes, remember to use the
710 non-shared construction for running on a single core.
711 use MCE::Shared::Cache;
713 my $cache = MCE::Shared::Cache->new( max_keys => 500_000 );
715 Otherwise, the following is a parallel version for a benchmark script
717 <https://blog.celogeek.com/201401/426/perl-benchmark-cache-with-
718 expires-and-max-size> found on the web. The serial version was created
719 by Celogeek for benchmarking various caching modules.
720 The MCE "progress" option makes it possible to track progress while
722 running parallel. This script involves IPC to and from the shared-
723 manager process, where the data resides. In regards to IPC, fetches may
724 take longer on Linux versus Darwin or FreeBSD.
725 #!/usr/bin/perl
727 use strict;
729 use warnings;
730 use feature qw( say );
731 use Digest::MD5 qw( md5_base64 );
733 use Time::HiRes qw( time );
734 use MCE 1.814;
735 use MCE::Shared;
736 $| = 1; srand(0);
738 # construct shared variables
740 # serialization is handled automatically
741 my $c = MCE::Shared->cache( max_keys => 500_000 );
743 my $found = MCE::Shared->scalar( 0 );
744 # construct and spawn MCE workers
746 # workers increment a local variable $f
747 my $mce = MCE->new(
749 chunk_size => 4000,
750 max_workers => 4,
751 user_func => sub {
752 my ($mce, $chunk_ref, $chunk_id) = @_;
753 if ( $mce->user_args()->[0] eq 'setter' ) {
754 for ( @{ $chunk_ref } ) { $c->set($_, {md5 => $_}) }
755 }
756 else {
757 my $f = 0;
758 for ( @{ $chunk_ref } ) { $f++ if ref $c->get($_) eq 'HASH' }
759 $found->incrby($f);
760 }
761 }
762 )->spawn();
763 say "Mapping";
765 my @todo = map { md5_base64($_) } ( 1 .. 600_000 );
766 say "Starting";
768 my ( $read, $write );
769 {
771 my $s = time;
772 $mce->process({
773 progress => sub { print "Write: $_[0]\r" },
774 user_args => [ 'setter' ],
775 }, \@todo);
776 $write = time - $s;
777 }
778 say "Write: ", sprintf("%0.3f", scalar(@todo) / $write);
780 {
782 my $s = time;
783 $found->set(0);
784 $mce->process({
785 progress => sub { print "Read $_[0]\r" },
786 user_args => [ 'getter' ],
787 }, \@todo);
788 $read = time - $s;
789 }
790 $mce->shutdown();
792 say "Read : ", sprintf("%0.3f", scalar(@todo) / $read);
794 say "Found: ", $found->get();
795 The "progress" option is further described on Metacpan. Several
797 examples are provided, accommodating all input data-types in MCE.
798 Progress Demonstrations <https://metacpan.org/pod/MCE::Core#PROGRESS-
800 DEMONSTRATIONS>
801
803 • CHI
804 • Cache::FastMmap
806 • Cache::LRU
808 • Cache::Ref
810 • Tie::Cache::LRU
812 • Tie::Cache::LRU::Expires
814
816 MCE, MCE::Hobo, MCE::Shared
817
819 Mario E. Roy, <marioeroy AT gmail DOT com>
820perl v5.38.0 2023-09-14 MCE::Shared::Cache(3)