Commit | Line | Data |
f0276afb |
1 | package DBM::Deep::Engine::Sector::Reference; |
2 | |
3 | use 5.006_000; |
4 | |
5 | use strict; |
6 | use warnings FATAL => 'all'; |
7 | |
8 | use base qw( DBM::Deep::Engine::Sector::Data ); |
9 | |
5ae752e2 |
10 | my $STALE_SIZE = 2; |
11 | |
12 | # Please refer to the pack() documentation for further information |
13 | my %StP = ( |
14 | 1 => 'C', # Unsigned char value (no order needed as it's just one byte) |
15 | 2 => 'n', # Unsigned short in "network" (big-endian) order |
16 | 4 => 'N', # Unsigned long in "network" (big-endian) order |
17 | 8 => 'Q', # Usigned quad (no order specified, presumably machine-dependent) |
18 | ); |
19 | |
f0276afb |
20 | sub _init { |
21 | my $self = shift; |
22 | |
23 | my $e = $self->engine; |
24 | |
25 | unless ( $self->offset ) { |
26 | my $classname = Scalar::Util::blessed( delete $self->{data} ); |
27 | my $leftover = $self->size - $self->base_size - 3 * $e->byte_size; |
28 | |
29 | my $class_offset = 0; |
30 | if ( defined $classname ) { |
31 | my $class_sector = DBM::Deep::Engine::Sector::Scalar->new({ |
32 | engine => $e, |
33 | data => $classname, |
34 | }); |
35 | $class_offset = $class_sector->offset; |
36 | } |
37 | |
38 | $self->{offset} = $e->_request_data_sector( $self->size ); |
39 | $e->storage->print_at( $self->offset, $self->type ); # Sector type |
40 | # Skip staleness counter |
41 | $e->storage->print_at( $self->offset + $self->base_size, |
42 | pack( $StP{$e->byte_size}, 0 ), # Index/BList loc |
43 | pack( $StP{$e->byte_size}, $class_offset ), # Classname loc |
44 | pack( $StP{$e->byte_size}, 1 ), # Initial refcount |
45 | chr(0) x $leftover, # Zero-fill the rest |
46 | ); |
47 | } |
48 | else { |
49 | $self->{type} = $e->storage->read_at( $self->offset, 1 ); |
50 | } |
51 | |
52 | $self->{staleness} = unpack( |
53 | $StP{$STALE_SIZE}, |
54 | $e->storage->read_at( $self->offset + $e->SIG_SIZE, $STALE_SIZE ), |
55 | ); |
56 | |
57 | return; |
58 | } |
59 | |
60 | sub staleness { $_[0]{staleness} } |
61 | |
62 | sub get_data_location_for { |
63 | my $self = shift; |
64 | my ($args) = @_; |
65 | |
66 | # Assume that the head is not allowed unless otherwise specified. |
67 | $args->{allow_head} = 0 unless exists $args->{allow_head}; |
68 | |
69 | # Assume we don't create a new blist location unless otherwise specified. |
70 | $args->{create} = 0 unless exists $args->{create}; |
71 | |
72 | my $blist = $self->get_bucket_list({ |
73 | key_md5 => $args->{key_md5}, |
74 | key => $args->{key}, |
75 | create => $args->{create}, |
76 | }); |
77 | return unless $blist && $blist->{found}; |
78 | |
79 | # At this point, $blist knows where the md5 is. What it -doesn't- know yet |
80 | # is whether or not this transaction has this key. That's part of the next |
81 | # function call. |
82 | my $location = $blist->get_data_location_for({ |
83 | allow_head => $args->{allow_head}, |
84 | }) or return; |
85 | |
86 | return $location; |
87 | } |
88 | |
89 | sub get_data_for { |
90 | my $self = shift; |
91 | my ($args) = @_; |
92 | |
93 | my $location = $self->get_data_location_for( $args ) |
94 | or return; |
95 | |
96 | return $self->engine->_load_sector( $location ); |
97 | } |
98 | |
99 | sub write_data { |
100 | my $self = shift; |
101 | my ($args) = @_; |
102 | |
103 | my $blist = $self->get_bucket_list({ |
104 | key_md5 => $args->{key_md5}, |
105 | key => $args->{key}, |
106 | create => 1, |
107 | }) or DBM::Deep->_throw_error( "How did write_data fail (no blist)?!" ); |
108 | |
109 | # Handle any transactional bookkeeping. |
110 | if ( $self->engine->trans_id ) { |
111 | if ( ! $blist->has_md5 ) { |
112 | $blist->mark_deleted({ |
113 | trans_id => 0, |
114 | }); |
115 | } |
116 | } |
117 | else { |
118 | my @trans_ids = $self->engine->get_running_txn_ids; |
119 | if ( $blist->has_md5 ) { |
120 | if ( @trans_ids ) { |
121 | my $old_value = $blist->get_data_for; |
122 | foreach my $other_trans_id ( @trans_ids ) { |
123 | next if $blist->get_data_location_for({ |
124 | trans_id => $other_trans_id, |
125 | allow_head => 0, |
126 | }); |
127 | $blist->write_md5({ |
128 | trans_id => $other_trans_id, |
129 | key => $args->{key}, |
130 | key_md5 => $args->{key_md5}, |
131 | value => $old_value->clone, |
132 | }); |
133 | } |
134 | } |
135 | } |
136 | else { |
137 | if ( @trans_ids ) { |
138 | foreach my $other_trans_id ( @trans_ids ) { |
139 | #XXX This doesn't seem to possible to ever happen . . . |
140 | next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 }); |
141 | $blist->mark_deleted({ |
142 | trans_id => $other_trans_id, |
143 | }); |
144 | } |
145 | } |
146 | } |
147 | } |
148 | |
149 | #XXX Is this safe to do transactionally? |
150 | # Free the place we're about to write to. |
151 | if ( $blist->get_data_location_for({ allow_head => 0 }) ) { |
152 | $blist->get_data_for({ allow_head => 0 })->free; |
153 | } |
154 | |
155 | $blist->write_md5({ |
156 | key => $args->{key}, |
157 | key_md5 => $args->{key_md5}, |
158 | value => $args->{value}, |
159 | }); |
160 | } |
161 | |
162 | sub delete_key { |
163 | my $self = shift; |
164 | my ($args) = @_; |
165 | |
c803879b |
166 | # This can return nothing if we are deleting an entry in a hashref that was |
167 | # auto-vivified as part of the delete process. For example: |
168 | # my $x = {}; |
169 | # delete $x->{foo}{bar}; |
f0276afb |
170 | my $blist = $self->get_bucket_list({ |
171 | key_md5 => $args->{key_md5}, |
c803879b |
172 | }) or return; |
f0276afb |
173 | |
174 | # Save the location so that we can free the data |
175 | my $location = $blist->get_data_location_for({ |
176 | allow_head => 0, |
177 | }); |
178 | my $old_value = $location && $self->engine->_load_sector( $location ); |
179 | |
180 | my @trans_ids = $self->engine->get_running_txn_ids; |
181 | |
182 | # If we're the HEAD and there are running txns, then we need to clone this value to the other |
183 | # transactions to preserve Isolation. |
184 | if ( $self->engine->trans_id == 0 ) { |
185 | if ( @trans_ids ) { |
186 | foreach my $other_trans_id ( @trans_ids ) { |
187 | next if $blist->get_data_location_for({ trans_id => $other_trans_id, allow_head => 0 }); |
188 | $blist->write_md5({ |
189 | trans_id => $other_trans_id, |
190 | key => $args->{key}, |
191 | key_md5 => $args->{key_md5}, |
192 | value => $old_value->clone, |
193 | }); |
194 | } |
195 | } |
196 | } |
197 | |
198 | my $data; |
199 | if ( @trans_ids ) { |
200 | $blist->mark_deleted( $args ); |
201 | |
202 | if ( $old_value ) { |
203 | $data = $old_value->data({ export => 1 }); |
204 | $old_value->free; |
205 | } |
206 | } |
207 | else { |
208 | $data = $blist->delete_md5( $args ); |
209 | } |
210 | |
211 | return $data; |
212 | } |
213 | |
d8f1fa98 |
214 | sub clear { |
215 | my $self = shift; |
216 | |
217 | my $blist_loc = $self->get_blist_loc or return; |
218 | |
219 | my $engine = $self->engine; |
220 | |
221 | if($engine->get_running_txn_ids) { |
222 | # ~~~ Temporary; the code below this block needs to be modified to |
223 | # take transactions into account. |
224 | $self->data->_clear; |
225 | return; |
226 | } |
227 | |
228 | my $sector = $engine->_load_sector( $blist_loc ) |
229 | or DBM::Deep->_throw_error( |
230 | "Cannot read sector at $blist_loc in clear()" |
231 | ); |
232 | |
233 | # Set blist offset to 0 |
234 | $engine->storage->print_at( $self->offset + $self->base_size, |
235 | pack( $StP{$engine->byte_size}, 0 ), |
236 | ); |
237 | |
238 | # Free the blist |
239 | $sector->free; |
240 | |
241 | return; |
242 | } |
243 | |
f0276afb |
244 | sub get_blist_loc { |
245 | my $self = shift; |
246 | |
247 | my $e = $self->engine; |
248 | my $blist_loc = $e->storage->read_at( $self->offset + $self->base_size, $e->byte_size ); |
249 | return unpack( $StP{$e->byte_size}, $blist_loc ); |
250 | } |
251 | |
252 | sub get_bucket_list { |
253 | my $self = shift; |
254 | my ($args) = @_; |
255 | $args ||= {}; |
256 | |
257 | # XXX Add in check here for recycling? |
258 | |
259 | my $engine = $self->engine; |
260 | |
261 | my $blist_loc = $self->get_blist_loc; |
262 | |
263 | # There's no index or blist yet |
264 | unless ( $blist_loc ) { |
265 | return unless $args->{create}; |
266 | |
267 | my $blist = DBM::Deep::Engine::Sector::BucketList->new({ |
268 | engine => $engine, |
269 | key_md5 => $args->{key_md5}, |
270 | }); |
271 | |
272 | $engine->storage->print_at( $self->offset + $self->base_size, |
273 | pack( $StP{$engine->byte_size}, $blist->offset ), |
274 | ); |
275 | |
276 | return $blist; |
277 | } |
278 | |
279 | my $sector = $engine->_load_sector( $blist_loc ) |
280 | or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" ); |
281 | my $i = 0; |
282 | my $last_sector = undef; |
283 | while ( $sector->isa( 'DBM::Deep::Engine::Sector::Index' ) ) { |
284 | $blist_loc = $sector->get_entry( ord( substr( $args->{key_md5}, $i++, 1 ) ) ); |
285 | $last_sector = $sector; |
286 | if ( $blist_loc ) { |
287 | $sector = $engine->_load_sector( $blist_loc ) |
288 | or DBM::Deep->_throw_error( "Cannot read sector at $blist_loc in get_bucket_list()" ); |
289 | } |
290 | else { |
291 | $sector = undef; |
292 | last; |
293 | } |
294 | } |
295 | |
296 | # This means we went through the Index sector(s) and found an empty slot |
297 | unless ( $sector ) { |
298 | return unless $args->{create}; |
299 | |
300 | DBM::Deep->_throw_error( "No last_sector when attempting to build a new entry" ) |
301 | unless $last_sector; |
302 | |
303 | my $blist = DBM::Deep::Engine::Sector::BucketList->new({ |
304 | engine => $engine, |
305 | key_md5 => $args->{key_md5}, |
306 | }); |
307 | |
308 | $last_sector->set_entry( ord( substr( $args->{key_md5}, $i - 1, 1 ) ) => $blist->offset ); |
309 | |
310 | return $blist; |
311 | } |
312 | |
313 | $sector->find_md5( $args->{key_md5} ); |
314 | |
315 | # See whether or not we need to reindex the bucketlist |
39baa1fd |
316 | # Yes, the double-braces are there for a reason. if() doesn't create a |
317 | # redo-able block, so we have to create a bare block within the if() for |
318 | # redo-purposes. |
319 | # Patch and idea submitted by sprout@cpan.org. -RobK, 2008-01-09 |
f0276afb |
320 | if ( !$sector->has_md5 && $args->{create} && $sector->{idx} == -1 ) {{ |
321 | my $redo; |
322 | |
323 | my $new_index = DBM::Deep::Engine::Sector::Index->new({ |
324 | engine => $engine, |
325 | }); |
326 | |
327 | my %blist_cache; |
328 | #XXX q.v. the comments for this function. |
329 | foreach my $entry ( $sector->chopped_up ) { |
330 | my ($spot, $md5) = @{$entry}; |
331 | my $idx = ord( substr( $md5, $i, 1 ) ); |
332 | |
333 | # XXX This is inefficient |
334 | my $blist = $blist_cache{$idx} |
335 | ||= DBM::Deep::Engine::Sector::BucketList->new({ |
336 | engine => $engine, |
337 | }); |
338 | |
339 | $new_index->set_entry( $idx => $blist->offset ); |
340 | |
341 | my $new_spot = $blist->write_at_next_open( $md5 ); |
342 | $engine->reindex_entry( $spot => $new_spot ); |
343 | } |
344 | |
345 | # Handle the new item separately. |
346 | { |
347 | my $idx = ord( substr( $args->{key_md5}, $i, 1 ) ); |
348 | |
349 | # If all the previous blist's items have been thrown into one |
350 | # blist and the new item belongs in there too, we need |
351 | # another index. |
352 | if ( keys %blist_cache == 1 and each %blist_cache == $idx ) { |
353 | ++$i, ++$redo; |
354 | } else { |
355 | my $blist = $blist_cache{$idx} |
356 | ||= DBM::Deep::Engine::Sector::BucketList->new({ |
357 | engine => $engine, |
358 | }); |
359 | |
360 | $new_index->set_entry( $idx => $blist->offset ); |
361 | |
362 | #XXX THIS IS HACKY! |
363 | $blist->find_md5( $args->{key_md5} ); |
364 | $blist->write_md5({ |
365 | key => $args->{key}, |
366 | key_md5 => $args->{key_md5}, |
367 | value => DBM::Deep::Engine::Sector::Null->new({ |
368 | engine => $engine, |
369 | data => undef, |
370 | }), |
371 | }); |
372 | } |
373 | # my $blist = $blist_cache{$idx} |
374 | # ||= DBM::Deep::Engine::Sector::BucketList->new({ |
375 | # engine => $engine, |
376 | # }); |
377 | # |
378 | # $new_index->set_entry( $idx => $blist->offset ); |
379 | # |
380 | # #XXX THIS IS HACKY! |
381 | # $blist->find_md5( $args->{key_md5} ); |
382 | # $blist->write_md5({ |
383 | # key => $args->{key}, |
384 | # key_md5 => $args->{key_md5}, |
385 | # value => DBM::Deep::Engine::Sector::Null->new({ |
386 | # engine => $engine, |
387 | # data => undef, |
388 | # }), |
389 | # }); |
390 | } |
391 | |
392 | if ( $last_sector ) { |
393 | $last_sector->set_entry( |
394 | ord( substr( $args->{key_md5}, $i - 1, 1 ) ), |
395 | $new_index->offset, |
396 | ); |
397 | } else { |
398 | $engine->storage->print_at( $self->offset + $self->base_size, |
399 | pack( $StP{$engine->byte_size}, $new_index->offset ), |
400 | ); |
401 | } |
402 | |
403 | $sector->clear; |
404 | $sector->free; |
405 | |
406 | if ( $redo ) { |
407 | (undef, $sector) = %blist_cache; |
408 | $last_sector = $new_index; |
409 | redo; |
410 | } |
411 | |
412 | $sector = $blist_cache{ ord( substr( $args->{key_md5}, $i, 1 ) ) }; |
413 | $sector->find_md5( $args->{key_md5} ); |
414 | }} |
415 | |
416 | return $sector; |
417 | } |
418 | |
419 | sub get_class_offset { |
420 | my $self = shift; |
421 | |
422 | my $e = $self->engine; |
423 | return unpack( |
424 | $StP{$e->byte_size}, |
425 | $e->storage->read_at( |
426 | $self->offset + $self->base_size + 1 * $e->byte_size, $e->byte_size, |
427 | ), |
428 | ); |
429 | } |
430 | |
431 | sub get_classname { |
432 | my $self = shift; |
433 | |
434 | my $class_offset = $self->get_class_offset; |
435 | |
436 | return unless $class_offset; |
437 | |
438 | return $self->engine->_load_sector( $class_offset )->data; |
439 | } |
440 | |
441 | sub data { |
442 | my $self = shift; |
443 | my ($args) = @_; |
444 | $args ||= {}; |
445 | |
446 | my $obj; |
447 | unless ( $obj = $self->engine->cache->{ $self->offset } ) { |
448 | $obj = DBM::Deep->new({ |
449 | type => $self->type, |
450 | base_offset => $self->offset, |
451 | staleness => $self->staleness, |
452 | storage => $self->engine->storage, |
453 | engine => $self->engine, |
454 | }); |
455 | |
456 | if ( $self->engine->storage->{autobless} ) { |
457 | my $classname = $self->get_classname; |
458 | if ( defined $classname ) { |
459 | bless $obj, $classname; |
460 | } |
461 | } |
462 | |
463 | $self->engine->cache->{$self->offset} = $obj; |
464 | } |
465 | |
466 | # We're not exporting, so just return. |
467 | unless ( $args->{export} ) { |
468 | return $obj; |
469 | } |
470 | |
471 | # We shouldn't export if this is still referred to. |
472 | if ( $self->get_refcount > 1 ) { |
473 | return $obj; |
474 | } |
475 | |
476 | return $obj->export; |
477 | } |
478 | |
479 | sub free { |
480 | my $self = shift; |
481 | |
482 | # We're not ready to be removed yet. |
483 | if ( $self->decrement_refcount > 0 ) { |
484 | return; |
485 | } |
486 | |
487 | # Rebless the object into DBM::Deep::Null. |
488 | eval { %{ $self->engine->cache->{ $self->offset } } = (); }; |
489 | eval { @{ $self->engine->cache->{ $self->offset } } = (); }; |
490 | bless $self->engine->cache->{ $self->offset }, 'DBM::Deep::Null'; |
491 | delete $self->engine->cache->{ $self->offset }; |
492 | |
493 | my $blist_loc = $self->get_blist_loc; |
494 | $self->engine->_load_sector( $blist_loc )->free if $blist_loc; |
495 | |
496 | my $class_loc = $self->get_class_offset; |
497 | $self->engine->_load_sector( $class_loc )->free if $class_loc; |
498 | |
499 | $self->SUPER::free(); |
500 | } |
501 | |
502 | sub increment_refcount { |
503 | my $self = shift; |
504 | |
505 | my $refcount = $self->get_refcount; |
506 | |
507 | $refcount++; |
508 | |
509 | $self->write_refcount( $refcount ); |
510 | |
511 | return $refcount; |
512 | } |
513 | |
514 | sub decrement_refcount { |
515 | my $self = shift; |
516 | |
517 | my $refcount = $self->get_refcount; |
518 | |
519 | $refcount--; |
520 | |
521 | $self->write_refcount( $refcount ); |
522 | |
523 | return $refcount; |
524 | } |
525 | |
526 | sub get_refcount { |
527 | my $self = shift; |
528 | |
529 | my $e = $self->engine; |
530 | return unpack( |
531 | $StP{$e->byte_size}, |
532 | $e->storage->read_at( |
533 | $self->offset + $self->base_size + 2 * $e->byte_size, $e->byte_size, |
534 | ), |
535 | ); |
536 | } |
537 | |
538 | sub write_refcount { |
539 | my $self = shift; |
540 | my ($num) = @_; |
541 | |
542 | my $e = $self->engine; |
543 | $e->storage->print_at( |
544 | $self->offset + $self->base_size + 2 * $e->byte_size, |
545 | pack( $StP{$e->byte_size}, $num ), |
546 | ); |
547 | } |
548 | |
549 | 1; |
550 | __END__ |